United States Prevention, Pesticides EPA 738-R-98-020

Environmental Protection And Toxic Substances December 1998

Agency (7508C)

Reregistration

Eligibility Decision (RED)

Alachlor
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF 

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

CERTIFIED MAIL

Dear Registrant:

I am pleased to announce that the Environmental Protection Agency has completed its

reregistration eligibility review and decisions on the pesticide chemical case alachlor. The

enclosed Reregistration Eligibility Decision (RED), which was approved on September 30, 1998,

contains the Agency's evaluation of the data base of these chemicals, its conclusions of the

potential human health and environmental risks of the current product uses, and its decisions and

conditions under which these uses and products will be eligible for reregistration. The RED

includes the data and labeling requirements for products for reregistration. It also includes

requirements for additional generic data on alachlor to confirm the risk assessments.

To assist you with a proper response, read the enclosed document entitled "Summary of

Instructions for Responding to the RED.” This summary also refers to other enclosed documents

which include further instructions. You must follow all instructions and submit complete and

timely responses. The first set of required responses is due 90 days from the date of your

receipt of this letter. The second set of required responses is due 8 months from the date of

your receipt of this letter. Complete and timely responses will avoid the Agency taking the

enforcement action of suspension against your products.

Please note that the Food Quality Protection Act of 1996 (FQPA) became effective on

August 3, 1996, amending portions of both pesticide law (FIFRA) and the food and drug law

(FFDCA). This RED takes into account, to the extent currently possible, the new safety standard

set by FQPA for establishing and reassessing tolerances. However, it should be noted that in

continuing to make reregistration determinations during the early stages of FQPA implementation,

EPA recognizes that it will be necessary to make decisions relating to FQPA before the

implementation process is complete. In making these early case-by-case decisions, EPA does not

intend to set broad precedents for the application of FQPA. Rather, these early determinations

will be made on a case-by-case basis and will not bind EPA as it proceeds with further policy

development and any rulemaking that may be required.
If EPA determines, as a result of this later implementation process, that any of the

determinations described in this RED are no longer appropriate, the Agency will pursue whatever

action may be appropriate, including but not limited to reconsideration of any portion of this

RED.

If you have questions on the product specific data requirements or wish to meet with the

Agency, please contact the Special Review and Reregistration Division representative Kathryn

Boyle at (703) 305-6304. 

Sincerely yours,

Jack E. Housenger, Acting Director

Special Review and Reregistration Division

Enclosures
SUMMARY OF INSTRUCTIONS FOR RESPONDING TO

THE REREGISTRATION ELIGIBILITY DECISION (RED)

1. DATA CALL-IN (DCI) OR "90-DAY RESPONSE"--If generic data are required for

reregistration, a DCI letter will be enclosed describing such data. If product specific data are

required, a DCI letter will be enclosed listing such requirements. If both generic and product

specific data are required, a combined Generic and Product Specific DCI letter will be enclosed

describing such data. However, if you are an end-use product registrant only and have been

granted a generic data exemption (GDE) by EPA, you are being sent only the product specific

response forms (2 forms) with the RED. Registrants responsible for generic data are being sent

response forms for both generic and product specific data requirements (4 forms). You must

submit the appropriate response forms (following the instructions provided) within 90 days

of the receipt of this RED/DCI letter; otherwise, your product may be suspended.

2. TIME EXTENSIONS AND DATA WAIVER REQUESTS--No time extension requests

will be granted for the 90-day response. Time extension requests may be submitted only with

respect to actual data submissions. Requests for time extensions for product specific data should

be submitted in the 90-day response. Requests for data waivers must be submitted as part of the

90-day response. All data waiver and time extension requests must be accompanied by a full

justification. All waivers and time extensions must be granted by EPA in order to go into effect.

3. APPLICATION FOR REREGISTRATION OR "8-MONTH RESPONSE"--You must

submit the following items for each product within eight months of the date of this letter

(RED issuance date).

a. Application for Reregistration (EPA Form 8570-1). Use only an original application

form. Mark it "Application for Reregistration." Send your Application for Reregistration (along

with the other forms listed in b-e below) to the address listed in item 5.

b. Five copies of draft labeling which complies with the RED and current regulations

and requirements. Only make labeling changes which are required by the RED and current

regulations (40 CFR 156.10) and policies. Submit any other amendments (such as formulation

changes, or labeling changes not related to reregistration) separately. You may, but are not

required to, delete uses which the RED says are ineligible for reregistration. For further labeling

guidance, refer to the labeling section of the EPA publication "General Information on Applying

for Registration in the U.S., Second Edition, August 1992" (available from the National Technical

Information Service, publication #PB92-221811; telephone number 703-605-6000).

c. Generic or Product Specific Data. Submit all data in a format which complies with

PR Notice 86-5, and/or submit citations of data already submitted and give the EPA identifier

(MRID) numbers. Before citing these studies, you must make sure that they meet the

Agency's acceptance criteria (attached to the DCI).

d. Two copies of the Confidential Statement of Formula (CSF) for each basic and

each alternate formulation. The labeling and CSF which you submit for each product must
comply with P.R. Notice 91-2 by declaring the active ingredient as the nominal concentration. 

You have two options for submitting a CSF: (1) accept the standard certified limits (see 40 CFR

§158.175) or (2) provide certified limits that are supported by the analysis of five batches. If you

choose the second option, you must submit or cite the data for the five batches along with a

certification statement as described in 40 CFR §158.175(e). A copy of the CSF is enclosed;

follow the instructions on its back.

e. Certification With Respect to Citation of Data and Data Matrix. Complete and

sign EPA forms 8570-34 and 8570-35 for each product. 

4. COMMENTS IN RESPONSE TO FEDERAL REGISTER NOTICE--Comments

pertaining to the content of the RED may be submitted to the address shown in the Federal

Register Notice which announces the availability of this RED.

5. WHERE TO SEND PRODUCT SPECIFIC DCI RESPONSES (90-DAY) AND

APPLICATIONS FOR REREGISTRATION (8-MONTH RESPONSES)

By U.S. Mail:

Document Processing Desk (RED-SRRD-PRB)

Office of Pesticide Programs (7504C)

 EPA, 401 M St. S.W.

Washington, D.C. 20460-0001

By express:

Document Processing Desk (RED-SRRD-PRB)

Office of Pesticide Programs (7504C) 

Room 266A, Crystal Mall 2 

1921 Jefferson Davis Hwy. 

Arlington, VA 22202

6. EPA'S REVIEWS--EPA will screen all submissions for completeness; those which are not

complete will be returned with a request for corrections. EPA will try to respond to data waiver

and time extension requests within 60 days. EPA will also try to respond to all 8-month

submissions with a final reregistration determination within 14 months after the RED has been

issued. 

ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF PESTICIDE PROGRAMS

SPECIAL REVIEW AND REREGISTRATION DIVISION

REREGISTRATION ELIGIBILITY DECISION

Alachlor

LIST A

CASE 0063
TABLE OF CONTENTS

ALACHLOR REREGISTRATION ELIGIBILITY DECISION TEAM ............... i

EXECUTIVE SUMMARY ................................................... v

I. INTRODUCTION .................................................... 1

II. CASE OVERVIEW ................................................... 2

A. Chemical Overview ............................................. 2

B. Use Profile ..................................................... 2

C. Estimated Usage of Pesticide ...................................... 4

D. Data Requirements .............................................. 5

E. Regulatory History .............................................. 5

III. SCIENCE ASSESSMENT .............................................. 7

A. Physical Chemistry Assessment .................................... 7

B. Human Health Assessment ....................................... 8

1. Toxicology Assessment ..................................... 8

a. Acute Toxicity ..................................... 10

b. Subchronic Toxicity ................................ 11

c. Chronic Toxicity and Carcinogenicity .................. 12

d. Developmental Toxicity .............................. 16

e. Reproductive Toxicity ............................... 16

f. Mutagenicity ...................................... 17

g. Metabolism ....................................... 20

h. Special Studies ..................................... 23

i. ESA Metabolite of Alachlor .......................... 35

2. Dose Response Assessment ................................. 39

a. Reference Dose .................................... 39

b. Dermal Absorption ................................. 40

c. Cancer Classification ............................... 41

d. Other Toxicological Endpoints ........................ 44

e. Determination of the FQPA 10X Safety Factor ........... 48

3. Exposure Assessment ..................................... 50

a. Dietary Exposure ................................... 50

b. Dietary Exposure from Drinking Water ................. 58

c. Occupational ..................................... 63

4. Risk Characterization ..................................... 79

a. Dietary ........................................... 79

b. Drinking Water ................................... 86

c. Aggregate (Food and Water) ........................ 89
d. Occupational ..................................... 94

e. FQPA Considerations ............................. 108

C. Environmental Assessment ..................................... 112

1. Use Characterization .................................... 112

2. Ecological Toxicity Data .................................. 115

a. Terrestrial Animals ................................ 116

b. Aquatic Animals .................................. 118

c. Plants ........................................... 121

d. Conclusions ...................................... 123

3. Environmental Fate Data ................................. 123

a. Degradation ...................................... 123

b. Metabolism ...................................... 124

c. Mobility/Leachability of Alachlor .................... 126

d. Mobility of Alachlor Degradates ...................... 128

e. Volatility ........................................ 131

f. Field Dissipation .................................. 131

g. Bioaccumulation .................................. 134

h. Spray Drift ....................................... 134

4. Environmental Fate Assessment ........................... 134

a. Degradation and Metabolism ........................ 135

b. Mobility ......................................... 135

c. Bioaccumulation .................................. 136

d. Field Dissipation .................................. 136

e. Volatility ........................................ 137

f. Spray Drift ....................................... 137

5. Terrestrial Exposure Assessment ........................... 137

6. Ground Water Monitoring Data ........................... 138

a. Introduction ..................................... 138

b. Recent Groundwater Monitoring Data ................ 139

c. Possible Concerns ................................. 147

7. Surface Water Monitoring Data ........................... 147

a. Introduction ..................................... 147

b. Surface Water Data ................................ 148

c. Possible Concerns over Alachlor and Alachlor ESA in Surface

Water ........................................... 152

8. Water Resource Assessment ............................... 153

a. Ground Water Assessment .......................... 153

b. Surface Water Assessment .......................... 156

c. Alachlor Degradates in Water ....................... 158

9. Aquatic Exposure Assessment ............................. 158

10. Comparative Assessment with Other Acetanilides ............. 162

a. Environmental Fate Characteristics ................... 162

b. Ecotoxicity ....................................... 162

c. Comparative Assessment Tables for the Acetanilides Alachlor,

Acetochlor, Metolachlor, and Propachlor .............. 164
11. Environmental Risk Assessment ........................... 172

a. Introduction ..................................... 172

b. Risk to Nontarget Terrestrial Animals ................. 173

c. Risk to Nontarget Aquatic Animals ................... 174

d. Risk to Nontarget Plants ............................ 175

e. Aquatic LOC Exceedances .......................... 176

f. Environmental Risk Summary ....................... 179

IV. RISK MANAGEMENT AND REREGISTRATION DECISION ............. 179

A. Determination of Eligibility ..................................... 179

B. Determination of Eligibility Decision ............................. 180

1. Eligibility Decision ...................................... 180

2. Eligible and Ineligible Uses ............................... 180

C. Regulatory Position ........................................... 180

1. Food Quality Protection Act Findings ....................... 181

a. Determination of Safety for U.S. Population ............ 181

b. Determination of Safety for Infants and Children ........ 183

c. Endocrine Disrupter Effects ......................... 184

2. Tolerance Reassessment .................................. 184

3. Ecological Risk Mitigation ................................ 187

4. Surface Water Protection Measures ........................ 188

5. Ground Water Protection Measures ........................ 189

6. Restricted Use Classification .............................. 190

7. Pesticides Management Plan (PMP) Candidate ............... 190

8. Endangered Species Statement ............................ 191

9. Labeling Rationale ...................................... 191

10. Spray Drift Advisory .................................... 196

V. ACTIONS REQUIRED OF REGISTRANTS ............................ 196

A. Manufacturing-Use Products .................................... 196

1. Additional Generic Data Requirements ...................... 196

2. Labeling Requirements for Manufacturing-Use Products ....... 197

B. End-Use Products ............................................. 197

1. Additional Product-Specific Data Requirements .............. 197

2. Labeling Requirements for End-Use Products ................ 197

C. Existing Stocks ............................................... 210

VI. APPENDICES ....................................................... 211

A. Table of Use Patterns Subject to Reregistration ..................... 213

B. Table of the Generic Data Requirements and Studies Used to Make the

Reregistration Decision ........................................ 215

C. Citations Considered to be Part of the Data Base Supporting the Reregistration

Decision ..................................................... 227

D. Combined Generic and Product Specific Data Call-In ................ 258

1. Chemical Status Sheets ................................... 279
2. Combined Generic and Product Specific Data Call-In Response Forms

(Insert A) Plus Instructions ............................... 281

3. Generic and Product Specific Requirement Status and Registrant's

Response Forms (Insert B) and Instructions .................. 290

4. EPA Batching of End-Use Products for Meeting Data Requirements for

Reregistration .......................................... 304

5. List of All Registrants Sent This Data Call-In (insert) Notice .... 307

E. List of Available Related Documents and Electronically Available Forms 313
i

ALACHLOR REREGISTRATION ELIGIBILITY DECISION TEAM

Office of Pesticide Programs:

Biological and Economic Analysis Assessment

Neil Anderson Herbicide and Insecticide Branch

Arthur Grube Economic Analysis Branch

Cynthia Doucoure Science Information and Analysis Branch

Environmental Fate and Effects Risk Assessment

Nelson Thurman Environmental Risk Branch IV

Richard Felthousen Environmental Risk Branch IV

Jose Melendez Environmental Risk Branch IV

Sid Abel Environmental Risk Branch IV

Laurence Libelo Environmental Risk Branch IV

Health Effects Risk Assessment

Kathryn Boyle Reregistration Branch 1

Susan Hummel Chemistry and Exposure Branch 2

Stephen Dapson Toxicology Branch 2

Carol Lang Chemistry and Exposure Branch 1

Registration Division

Vickie Walters Herbicide Branch

Risk Management

Judith Loranger Reregistration Branch 3

Kathryn Boyle Reregistration Branch 3
ii
GLOSSARY OF TERMS AND ABBREVIATIONS

iii

ADI Acceptable Daily Intake. A now defunct term for reference dose (RfD).

AE Acid Equivalent

a.i. Active Ingredient

ARC Anticipated Residue Contribution 

CAS Chemical Abstracts Service

CI Cation

CNS Central Nervous System

CSF Confidential Statement of Formula

DFR Dislodgeable Foliar Residue

DRES Dietary Risk Evaluation System

DWEL Drinking Water Equivalent Level (DWEL) The DWEL represents a medium specific (i.e. drinking

water) lifetime exposure at which adverse, non carcinogenic health effects are not anticipated to

occur.

EEC Estimated Environmental Concentration. The estimated pesticide concentration in an environment,

such as a terrestrial ecosystem.

EP End-Use Product

EPA U.S. Environmental Protection Agency

FAO/WHO Food and Agriculture Organization/World Health Organization

FDA Food and Drug Administration

FIFRA Federal Insecticide, Fungicide, and Rodenticide Act

FFDCA Federal Food, Drug, and Cosmetic Act

FQPA Food Quality Protection Act

FOB Functional Observation Battery

GLC Gas Liquid Chromatography

GM Geometric Mean

GRAS Generally Recognized as Safe as Designated by FDA

HA Health Advisory (HA). The HA values are used as informal guidance to municipalities and other

organizations when emergency spills or contamination situations occur.

HDT Highest Dose Tested

LC50 Median Lethal Concentration. A statistically derived concentration of a substance that can be

expected to cause death in 50% of test animals. It is usually expressed as the weight of substance

per weight or volume of water, air or feed, e.g., mg/L, mg/kg or ppm.

LD50 Median Lethal Dose. A statistically derived single dose that can be expected to cause death in 50%

of the test animals when administered by the route indicated (oral, dermal, inhalation). It is

expressed as a weight of substance per unit weight of animal, e.g., mg/kg.

LDlo Lethal Dose-low. Lowest Dose at which lethality occurs.

LEL Lowest Effect Level

LOC Level of Concern

LOD Limit of Detection 

LOEC Lowest Observed Effect Concentration

LOEL Lowest Observed Effect Level

MATC Maximum Acceptable Toxicant Concentration

MCLG Maximum Contaminant Level Goal (MCLG) The MCLG is used by the Agency to regulate

contaminants in drinking water under the Safe Drinking Water Act.

μg/g Micrograms Per Gram

Fg/L Micrograms per liter

mg/L Milligrams Per Liter

MOE Margin of Exposure 

MP Manufacturing-Use Product
GLOSSARY OF TERMS AND ABBREVIATIONS

iv

MPI Maximum Permissible Intake

MRID Master Record Identification (number). EPA's system of recording and tracking studies submitted.

N/A Not Applicable

NOEC No Observable Effect Concentration

NPDES National Pollutant Discharge Elimination System

NOEL No Observed Effect Level

NOAEL No Observed Adverse Effect Level

OP Organophosphate

OPP Office of Pesticide Programs

Pa pascal, the pressure exerted by a force of one newton acting on an area of one square meter.

PADI Provisional Acceptable Daily Intake

PAG Pesticide Assessment Guideline

PAM Pesticide Analytical Method

PHED Pesticide Handler's Exposure Data 

PHI Preharvest Interval

ppb Parts Per Billion

PPE Personal Protective Equipment

ppm Parts Per Million

PRN Pesticide Registration Notice

Q

*

1 The Carcinogenic Potential of a Compound, Quantified by the EPA's Cancer Risk Model

RBC Red Blood Cell

RED Reregistration Eligibility Decision

REI Restricted Entry Interval

RfD Reference Dose

RS Registration Standard

RUP Restricted Use Pesticide

SLN Special Local Need (Registrations Under Section 24 (c) of FIFRA)

TC Toxic Concentration. The concentration at which a substance produces a toxic effect. 

TD Toxic Dose. The dose at which a substance produces a toxic effect.

TEP Typical End-Use Product

TGAI Technical Grade Active Ingredient

TLC Thin Layer Chromatography

TMRC Theoretical Maximum Residue Contribution

torr A unit of pressure needed to support a column of mercury 1 mm high under standard conditions.

TWMC Time Weighted Mean Concentration

WP Wettable Powder

WPS Worker Protection Standard
v

EXECUTIVE SUMMARY

This Reregistration Eligibility Decision Document (RED) addresses the reregistration

eligibility of the pesticide alachlor, 2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide. 

Alachlor is a herbicide used for weed control on corn, soybeans, sorghum, peanuts, and beans. There

are liquid, dry flowable, microencapsulated, and granular formulations. The timing of applications

is preplant, pre-emergent, at-plant for corn and soybeans, post-transplant, post-emergent, and at

ground crack for peanuts only. Alachlor is applied by ground, aerial, and chemigation equipment.

It can also be mixed with dry bulk fertilizer.

Alachlor was first registered in 1969 as a selective herbicide for control of broadleaf weeds

and grasses. Alachlor is produced by the Monsanto Company in the US.

EPA has completed its reregistration eligibility decision for the pesticide alachlor and

determined that all uses, when labeled and used as specified in this document, are eligible for

reregistration. This decision includes a comprehensive reassessment of the required target data base

supporting the use patterns of currently registered products. This decision considered the

requirements of the "Food Quality Protection Act of 1996" (FQPA) which amended the Federal Food

Drug and Cosmetic Act and the Federal Insecticide Fungicide and Rodenticide Act, the two Federal

statutes that provide the framework for pesticide regulation in the United States. FQPA became

effective immediately upon signature and all Reregistration Eligibility Decisions (REDs) signed

subsequent to August 3, 1996, are accordingly being evaluated under the new standards imposed by

FQPA.

Reregistration Eligibility

The Agency has concluded under the Federal Insecticide, Fungicide, and Rodenticide Act

(FIFRA) that all uses, as prescribed in this document, will not cause unreasonable risks to humans

or the environment and therefore all products are eligible for reregistration. The Agency has accepted

a risk mitigation measure, proposed by the technical registrant Monsanto, requiring application rate

reductions. To assure protection of ground water as a resource, Monsanto has offered to classify

alachlor as a Restricted Use Pesticide for ground water concerns. Certain ecological data, residue

chemistry data, and exposure data are required to confirm the Agency’s risk assessment and

conclusions. 

In establishing or reassessing tolerances, FQPA requires the Agency to consider aggregate

exposures to pesticide residues, including all anticipated dietary exposures and other exposures for

which there is reliable information, as well as the potential for cumulative effects from pesticides and

other compounds with a common mechanism of toxicity. FQPA further directs EPA to consider the

potential for increased susceptibility of infants and children to the toxic effects of pesticide residues,

and to develop a screening program to determine whether pesticides produce endocrine disrupting

effects. 
vi

FQPA requires that the Agency consider the cumulative effects of alachlor and other

chemicals that have a common mechanism of toxicity. The Agency first must determine if a common

mechanism of toxicity exists for a group of chemicals. If so, the Agency must decide on the

appropriate methodology for combining exposures, and then, after reviewing use

information/patterns, determine which of the exposures/scenarios for which chemicals are to be

combined, (i.e., cumulative exposure does occur.) 

Alachlor is structurally similar to four other pesticides: acetochlor, butachlor, propachlor, and

metolachlor. The Agency has not yet completed its assessment of whether or not these chemicals

actually have a common mechanism of toxicity. However, a presentation was made to the FIFRA

Scientific Advisory Panel (SAP) in March 1997 in which six chloroacetanilide chemicals were

presented as a case study. In this case study, several groupings of the chemicals were possible: 

I.acetochlor, alachlor and butachlor - based on structure activity relationships (SAR) consideration

of common reactive intermediates

II.acetochlor, alachlor, and butachlor - based on statistically significant increases in nasal tumors

(metolachlor nasal tumors were not statistically significant)

C acetochlor, alachlor, and butachlor - based on thyroid follicular cell tumors

C acetochlor, alachlor, propachlor, and butachlor - based on stomach tumors or lesions

C acetochlor, alachlor, and butachlor - based on kidney effects

C acetochlor, alachlor, propachlor, butachlor, and dimethamide - based on liver effects 

C dimethamide, metolachlor, and propachlor - based on liver tumors

At this time, no determination on the appropriate grouping to use in the assessment has been

made. The Agency is in the process of responding to comments resulting from the SAP. For

alachlor, neither the appropriate methodology for combining exposures nor the exposures to combine

has been determined. However, the Agency has just released a guidance document describing the

approach that EPA will use for identifying mechanisms of toxicity and categorizing pesticide

chemicals that have a common mechanism of toxicity. Additionally, the single chemical/multipathway assessments of each of the chemicals must be completed before the Agency could perform

the multi-chemical/multi-pathway assessment. Metolachlor was a 1995 RED. Acetochlor was

registered in the early 1990s. Both chemicals would need updated risk assessments. Propachlor is

also a 1998 RED. As a result, the Alachlor RED can only go forward at this time as a single

chemical/multi-pathway assessment. 

The Agency has reassessed all alachlor food and feed related tolerances under the standards

of FQPA and determined that, based on available information, there is a reasonable certainty that no

harm will result to infants and children or to the general population from aggregate exposure to

alachlor residues. The only type of exposures evaluated were dietary (food and drinking water)

exposures, since non-occupational exposures (primarily residential) are unlikely to occur with alachlor

use.
vii

Human Health Effects

Alachlor has been evaluated for carcinogenic activity in rats and mice. In accordance with

the 1996 EPA proposed Guidelines for Carcinogen Risk Assessment, alachlor was classified as

“likely” to be a human carcinogen at high doses, but “ not likely” at low doses. Based on numerous

studies submitted by the registrant that were reviewed by Agency scientists, as well as an external

peer review panel, it was agreed that a margin of exposure (MOE) approach (indicative of a nonlinear dose response) would be appropriate for evaluating carcinogenic risk in a human health risk

assessment.

The scientific validity of the MOE approach has been documented by various review panels,

such as the FIFRA Scientific Advisory Panel, and the Cancer Review Committee. However, the

policy implications, methodology, and appropriateness of using an MOE approach in regulatory

decision making have not yet been fully developed by the Agency. Perhaps, the most critical of the

decision criteria to develop are those for determining the appropriate regulatory level. While

informed by the science, this determination is ultimately a risk management decision. Once this

methodology has been developed, then the available chemical-specific data would be used to

determine whether or not the MOEs identified in the risk assessment constitute acceptable risks. 

For now, the regulatory decision for alachlor will be based on both the Q1

*

 approach and the

MOE approach for the evaluation of carcinogenic potential. These are not directly comparable

approaches. The Q1

*

 approach is indicative of a linear approach and reflects the assumption that any

exposure to alachlor could cause cancer. The MOE approach is indicative of a non-linear approach

and reflects the assumption that there is an exposure dose below which tumor formation is not likely

to occur. Thus, the risk numbers do not translate from one approach to the other. Each approach

must be considered separately. 

The alachlor database for pre-and post-natal effects is complete based on current

requirements. The Agency has reviewed two developmental toxicity studies: one in rats, and one

in rabbits. Developmental studies are designed to identify possible adverse effects on the developing

organism during pre-natal development which may result from the mother’s exposure to the

pesticide. For alachlor, there is also a multi-generation rat reproduction study. A reproduction study

is designed to provide general information concerning the effects of a test substance on mating

behavior, conception, parturition, lactation, weaning, and growth and development of the offspring.

In both of the developmental toxicity studies, the NOELs for developmental effects are the

same as the NOELs for maternal effects. Generally, the Agency would be particularly concerned

when developmental effects are seen at doses lower than those which cause maternal effects, i.e. a

situation in which the mother is not impacted, but the developing organism would be impacted. For

alachlor, there is no evidence of a unique sensitivity to the developing organism from pre-natal

exposure. In the reproductive toxicity study, the reproductive NOEL is higher than the systemic

NOEL, indicating that the parents would be impacted before the offspring. No special sensitivity for

infants or children is indicated. Thus, review by Agency scientists indicates no evidence of increased
viii

susceptibility of rats or rabbits to in utero and /or early postnatal exposure to alachlor. 

Based on this conclusion, as well as the available information on exposure to residues of

alachlor in food and water, the Agency has concluded that the additional safety factor, as required

by FQPA for the protection of infants and children, can be removed. Therefore, this safety factor

need not be applied to the alachlor risk assessment.

The toxicological effects of a pesticide can vary with different exposure durations and routes.

For example, an individual may be exposed throughout their lifetime to pesticide residues in the food

and water consumed, but a farm worker could also be exposed for several days or a month to a

pesticide by the dermal and/or inhalation routes of exposure. The Agency considers the entire

toxicity database and, based on the effects seen for different durations and routes of exposure,

determines which risk assessments are necessary to insure that the public is adequately protected from

any pesticide exposure. 

The alachlor reregistration eligibility review considered the following assessments to be

appropriate:

Assessment Exposure Route NOEL1 for Use in Estimating Risk

Acute Dietary 

(food and water)

Not required - no evidence of significant

toxicity from a one day or single event

exposure by the oral route

Chronic

(non-carcinogenic)

Dietary 

(food and water)

RfD2,3 = 0.01 mg/kg/day

Short-Term

Occupational

Dermal + Inhalation NOEL = 150 mg/kg/day

Use of dermal absorption factor (0.24)

required.4

Intermediate-Term Dermal + Inhalation NOEL = 50 mg/kg/day

Use of dermal absorption factor not required

since NOEL is from a dermal study.4

MOE Approach5

Carcinogenic

Dietary 

(food and water)

NOEL = 0.5 mg/kg/day (nasal)

NOEL = 14 mg/kg/day (stomach)

MOE Approach

Carcinogenic

Occupational

Dermal + Inhalation Not appropriate - Exposure assessment does

not indicate that use is long-term and

continuous.

Q1

*

 Approach6

Carcinogenic

Dietary 

(food and water)

Q1

*

 = 0.08 (mg/kg/day)-1
Assessment Exposure Route NOEL1

 for Use in Estimating Risk

ix

Residential Dermal + Inhalation Not appropriate - The Agency has not

identified any alachlor products that are

intended for home use, or uses in/around

schools, parks or other public areas.

1 A NOEL (no observed effect level) is the dose at which no effects were observed in the test

animals.

2 The chronic Reference Dose (RfD) is the traditionally selected endpoint for chronic dietary

risk. The RfD represents the quantity of a substance which if absorbed on a daily basis over

a lifetime, is not expected to pose significant risk of adverse health effects.

3 Acceptable risk is less than 100% of the RfD.

4 Acceptable risk results in a MOE that is greater than 100.

5 Acceptable risk has not been determined.

6 Acceptable risk is 1 x 10-6 , or lower.

Dietary Risk (Food Only)

People may be exposed to small amounts of alachlor through the consumption of food

containing residues of alachlor. Tolerances are pesticide residue levels that should not be exceeded

in or on a raw agricultural commodity in the channels of interstate commerce when the pesticide is

applied according to label directions. Tolerances have been established (see 40 CFR 180.249) for

residues of alachlor in/on a variety of food and feed commodities:

C beans, which includes dry beans, lima beans, forage and fodder; 

C corn, fresh sweet, and forage, fodder, and grain; 

C eggs; 

C milk; 

C peanuts, forage, hay, and hulls;

C sorghum, fodder, forage, and grain;

C soybeans, forage, and hay;

C meat and meat byproducts of cattle, goats, hogs, poultry and horses. 

Sufficient data are available to determine the adequacy of most established alachlor tolerances.

However, some tolerances need to be revoked, and some need to be increased. The reassessed

tolerances for alachlor will range from 0.02 to 10 ppm.

EPA has assessed the chronic (non-carcinogenic) dietary risk posed by alachlor. Using

refinements to the dietary assessment process and considering all food uses recommended through

reregistration, the Anticipated Residue Concentration (ARC) for the overall U.S. population

represents less than 1% of the chronic Reference Dose (RfD), the amount believed not to cause

adverse effects if consumed daily over a 70-year lifetime. The most highly exposed subgroup, nonnursing infants less than one year old, has an ARC which also represents less than 1% of the chronic

RfD. This low fraction of the allowable RfD is considered to be an acceptable dietary risk. 
x

EPA has assessed the carcinogenic dietary risk posed by alachlor by both the Q1

*

 approach

and the MOE approach. Both approaches are discussed below in the Aggregate Dietary Exposure

Discussion. 

Dietary Risk (Drinking Water Only)

People may be exposed to small amounts of alachlor through the consumption of water

containing residues of alachlor. Alachlor is regulated under the SDWA (Safe Drinking Water Act).

The MCL (Maximum Contaminant Level) for alachlor is 2 ppb. An MCL is the maximum permissible

level of a contaminant in drinking water that is delivered to any user of a public water supply system.

For alachlor, there is extensive monitoring data for both ground and surface water. 

EPA has assessed the chronic (non-carcinogenic) drinking water risk posed by alachlor.

Using the monitoring data for alachlor only and Agency assumptions on the amount of water

consumed, the estimated exposure represents less than 1% of the chronic Reference Dose (RfD), for

adult males, adult females, and children (1 - 6 years) sub-population groups. The Agency considers

this to be an acceptable risk due to consumption of drinking water containing small amounts of

alachlor.

EPA has assessed the carcinogenic drinking water risk posed by alachlor, using monitoring

data and Agency assumptions on the amount of water consumed, for both the Q1

*

 approach and the

MOE approach. Both approaches are discussed below in the Aggregate Dietary Exposure Discussion.

Aggregate Dietary Risk (Food and Drinking Water)

FQPA requires that the Agency consider aggregate risk, that is, exposure from all food, water,

and non-occupational, non-dietary exposures. For alachlor, the aggregate exposure is for food and

water only. The highest chronic risk was 4% of the chronic RfD which represents the sub-population

child (1 - 6 years). This was calculated considering both food and water containing residues of

alachlor as well as consumption of water containing residues of the alachlor ESA degradate. The

Agency considers this to be an acceptable risk. 

The aggregate carcinogenic risk using the Q1

*

 approach considers exposures from both food

and water. For adult males and adult females carcinogenic risks range from 7.8 x 10-7 to 1.4 x 10-6.

These risks are consistent with the carcinogenic level (1 x 10-6 ) that the Agency considers to be

negligible. 

The aggregate carcinogenic MOEs (food and drinking water) for adult males and adult

females vary from 29,000 to 1,400,000. At this time, the Agency is not making any conclusions

regarding the adequacy of these calculated MOEs for carcinogenic dietary risk. This is due to the fact

that the Agency has not yet made a final decision as to the appropriate uncertainty factors which

would be adequately protective of a carcinogenic endpoint regulated using a non-linear approach.

However, given that the cancer risk using the Q1

*

 approach is acceptable and that the magnitude of
xi

the calculated MOEs is quite large, the Agency believes that the dietary cancer risk from the use of

alachlor is not of concern.

A comparison of the two approaches is given in the following Table:

Comparison of Carcinogenic Dietary Assessments

Source of Water

used in

Assessment

Exposure

(food and water)

MOE 

(nasal tumors)

(MOE)

(stomach 

tumors)

Q1

*

Adult Male

NAWWS1

(ground water)

0.0000127 39,000 1,100,000 1.0 x 10-6

USGS2

(reservoir data)

0.0000132 38,000 1,100,000 1.1 x 10-6

ARP3

(surface water)

0.0000098 51,000 1,400,000 7.8 x 10-7

Adult Female

NAWWS

(ground water)

0.0000166 30,000 840,000 1.3 x 10-6

USGS 

(reservoir)

0.0000173 29,000 810,000 1.4 x 10-6

ARP

(surface water)

0.0000133 38,000 1,100,000 1.1 x 10-6

1 Data is from the National Alachlor Well Water Survey

2 Data is from the United States Geological Survey

3 Data is from the Acetochlor Registration Partnership

Occupational Risk

Based on current use patterns, handlers (mixers, loaders, and applicators) may be exposed to

alachlor during normal use of granular, liquid, and dry flowable formulations. No protective

equipment is required for the granular formulations. For worker protection, the Agency will require

the use of additional protective equipment (chemical resistant gloves, apron, and chemical resistant

shoes) when handling liquid and dry flowable formulations for workers supporting groundboom

applications. For workers supporting aerial applications, closed (mechanical transfer) systems will

be required for liquid formulations. Monsanto will be required to develop water soluble packaging

for dry flowable formulations for aerial applications. Closed (mechanical transfer) systems will be
xii

required for the dry bulk fertilizer impregnation process. 

The levels of protection required were based on the intermediate-term (one week to several

months) exposure scenario. The exposure assessment indicated that use of alachlor is an intermittent

exposure. The MOE methodology is consistent with a non-linear mechanism which requires

continuous exposure. Due to the existence of an exposure pattern that is intermittent (not long-term

and continuous), it is not appropriate to perform a carcinogenic MOE risk assessment for the

occupational scenario. 

Unlike the MOE approach to carcinogenic risk assessment, the Q1

*

 approach assumes that

any exposure could result in tumor formation. Thus, this type of assessment could be performed for

an intermittent exposure. However, the scientific validity of the MOE approach for carcinogenic risk

assessment of alachlor has been documented. Alachlor was classified as “likely” to be a carcinogen

at high doses, but “not likely” at low doses. It is only the policy on determining an appropriate

regulatory level that has not been fully developed by the Agency. Since, performing a carcinogenic

MOE risk assessment for the occupational scenario is not appropriate, a Q1

*

 carcinogenic

occupational assessment for comparison purposes is not necessary.

The potential for post-application worker exposure is negligible, provided the Restricted Entry

Interval (REI) of 12 hours is observed. This is due to the timing of applications. Alachlor is applied

to the soil and/or soil incorporated pre-plant, and pre-emergent. Thus the application of alachlor to

emerging plants, well before the plants are mature, mitigates the potential for post-application

exposure.

Environmental Assessment

The Environmental Fate Assessment for alachlor shows that:

C Alachlor has a low affinity to adsorb to soils and is expected to be highly mobile.

C Alachlor is moderately persistent and dissipates primarily by aerobic soil metabolism

processes with a half-life of 2-3 weeks.

C The major acid degradates of alachlor are very mobile and appear to be persistent.

C Field dissipation studies confirm this fate profile (half-life of 6-11 days; leaching through 42-

48 inches in one of the studies).

The Water Resources Assessment concludes that:

C Alachlor is highly mobile and moderately persistent. These two characteristics are generally

observed in chemicals that reach ground water and surface water.

C Alachlor presents a clear hazard to groundwater quality. Reliable monitoring studies have

demonstrated that alachlor, even when used according to the label instructions, results in

significant groundwater contamination. Alachlor use also results in groundwater in the use

areas being contaminated with degradation products, which are also very mobile and

persistent,

C Monitoring studies show that alachlor levels in surface water result in effects on aquatic plants
xiii

and indirectly on aquatic animals.

C Available information indicates that (surface) drinking water supply systems will usually

comply with the SDWA.

The available toxicity data for alachlor indicate that alachlor is:

C Slightly to practically non-toxic to birds on an acute oral basis (LD50 of 1500 mg/kg).

C Slightly toxic to mammals, based on a rat study (LD50 of 930 mg/kg).

C Slightly toxic to honey bees (LD50 >36 μg/bee).

C Slightly to moderately toxic on an acute basis to freshwater fish (LC50 1-33 ppm).

C Highly to moderately toxic to freshwater fish on a chronic basis (NOEC$0.1 ppm, LOEC$0.2

ppm).

C Moderately toxic to saltwater fish (3.9 ppm), moderately toxic to saltwater mysid (2.4 ppm)

and moderately toxic to shellfish (1.6 ppm).

C Highly toxic to aquatic plants (based on a single species tested: NOEL=0.35 ppb, LOEL=0.69

ppb, EC50=1.64ppb).

Therefore, a potential risk to nontarget terrestrial and aquatic plants, and endangered plant

species exists. Additionally, the available information on the major alachlor degradates indicates that

the degradates appear to be less toxic to aquatic organisms than the parent.

An evaluation of the risk to nontarget organisms from the use of alachlor products, combining

toxicity data with potential exposure, indicates that:

C Alachlor poses a potential risk to terrestrial animals on a chronic basis. Additional

information are required to confirm this assessment. 

C The granular formulations and high use rate pose the greatest risk to nontarget organisms. 

C Alachlor levels observed in surface water monitoring studies could result in extensive adverse

effects on aquatic plants.

C Aquatic animals are not at acute risk due to exposure to alachlor, but chronic effects may be

observed under certain circumstances.

The Agency has significant concerns about the impact alachlor and its degradates may have

on groundwater quality. Consideration of environmental chemistry and fate properties indicates that

alachlor and a number of alachlor degradates will leach to ground water. An extensive body of

groundwater monitoring information has been reviewed which confirms that alachlor and alachlor

degradates do in fact contaminate groundwater.

To mitigate these concerns, the Agency will:

C Classify alachlor as a Restricted Use Pesticide (RUP) for ground water concerns

C Add labeling language requiring a 50 ft setback of mixing and loading activities from wells,

rivers, or lakes unless such activity is protected by an impervious pad.

C After promulgation of the Ground Water and Pesticides Management Plan Rule, require use

in accordance with an approved State or Tribal Management Plan 
xiv

Product Reregistration

Before reregistering the products containing alachlor, the Agency is requiring that product

specific data, revised Confidential Statements of Formula (CSF) and revised labeling be submitted

within eight months of the issuance of this decision document. These data include product chemistry

for each registration and acute toxicity testing. After reviewing these data and any revised labels and

finding them acceptable in accordance with Section 3(c)(5) of FIFRA, the Agency will reregister a

product. Those products which contain other active ingredients will be eligible for reregistration only

when the other active ingredients are determined to be eligible for reregistration.
1

I. INTRODUCTION

In 1988, the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was amended to

accelerate the reregistration of products with active ingredients registered prior to November 1, 1984.

The amended Act provides a schedule for the reregistration process to be completed in nine years.

There are five phases to the reregistration process. The first four phases of the process focus on

identification of data requirements to support the reregistration of an active ingredient and the

generation and submission of data to fulfill the requirements. The fifth phase is a review by the U.S.

Environmental Protection Agency (referred to as "the Agency") of all data submitted to support

reregistration.

FIFRA Section 4(g)(2)(A) states that in Phase 5 "the Administrator shall determine whether

pesticides containing such active ingredient are eligible for reregistration" before calling in data on

products and either reregistering products or taking "other appropriate regulatory action." Thus,

reregistration involves a thorough review of the scientific data base underlying a pesticide's

registration. The purpose of the Agency's review is to reassess the potential hazards arising from the

currently registered uses of the pesticide; to determine the need for additional data on health and

environmental effects; and to determine whether the pesticide meets the "no unreasonable adverse

effects" criterion of FIFRA.

On August 3, 1996, the Food Quality Protection Act of 1996 (FQPA) (Public Law 104-170)

was signed into law. FQPA amends both the Federal Food, Drug, and Cosmetic Act (FFDCA), 21

U.S.C. 301 et seq., and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), 7 U.S.C.

136 et seq. The FQPA amendments went into effect immediately. As a result, EPA has embarked

on an intensive process, including consultation with registrants, States, and other interested

stakeholders, to make decisions on the new policies and procedures that will be appropriate as a result

of enactment of FQPA. This process includes a more in depth analysis of the new safety standard and

how it should be applied to both food and non-food use pesticides. The FQPA does not, however,

amend any of the existing reregistration deadlines set forth in §4 of FIFRA. In addition, in light of

the unaffected statutory deadlines with respect to reregistration, the Agency will continue its ongoing

reregistration program while it continues to determine how best to implement FQPA.

This document presents the Agency's decision regarding the reregistration eligibility of the

registered uses of alachlor including the risk to infants and children for any potential dietary, drinking

water, dermal or oral exposures, and cumulative effects as stipulated under the FQPA. The document

consists of six sections. Section I is the introduction. Section II describes alachlor, its uses, data

requirements and regulatory history. Section III discusses the human health and environmental

assessment based on the data available to the Agency. Section IV presents the reregistration decision

for alachlor. Section V discusses the reregistration requirements for alachlor. Finally, Section VI is

the Appendices which support this Reregistration Eligibility Decision. Additional details concerning

the Agency's review of applicable data are available on request.
2

II. CASE OVERVIEW

a. Chemical Overview

The following active ingredient is covered by this Reregistration Eligibility Decision:

! Common Name: Alachlor

! Chemical Name: 2-chloro-N-(2,6-diethylphenyl)-

N-(methoxymethyl)acetamide 

! Chemical Family: Acetanilide

! CAS Registry Number: 15972-60-8

! OPP Chemical Code: 090501

! Empirical Formula: C14H20NO2Cl

! Trade and Other Names: Lasso, Alanex

! Basic Manufacturer: Monsanto Chemical Company

b. Use Profile

The following is information on the currently registered uses with an overview of use sites and

application methods. A detailed table of these uses of alachlor is in Appendix A.

Type of Pesticide: Herbicide

Mode of Action: Chloroacetamides are known to inhibit biosynthesis of fatty acids,

lipids, protein, isoprenoids, flavonoids, and gibberellins. 

Use Sites:

TERRESTRIAL FOOD+FEED CROP

Crops Grown for Oil: Soybeans 

Grain Crops: Corn (Field), Sorghum 

Groups of Agricultural Crops Which Cross Established Crop Groupings: Corn (unspecified),

Peanuts (unspecified), Soybeans (unspecified)
3

Seed and Pod Vegetables: Beans (Dried-Type), Beans (Mung), Beans (Succulent, Lima),

Soybeans (Edible) 

Specialized Field Crops: Corn (Pop) 

TERRESTRIAL FEED CROP 

Forage Grasses: Corn

Forage Legumes and Other Nongrass Forage Crops: Soybeans 

TERRESTRIAL NON-FOOD+OUTDOOR RESIDENTIAL 

Ornamental Woody Shrubs and Vines

 

Target Pests for Single Active Ingredient Products:

Barnyardgrass, Crabgrass, Cupgrass (woolly), Foxtail (giant, green, robust, purple, yellow,

robust white), Goosegrass, Johnsongrass, Millet, Panicum (browntop, fall, Texas), Rice (red),

Sandbur, Grassbur, Shattercane (wildcane), Signalgrass (broadleaf), Red Sprangletop,

Witchgrass, Florida Beggarweed, Carpetweed, Cocklebur, Coffeeweed, Copperleaf,

Galinsoga, Groundcherry (annual), Groundcherry (cutleaf), Jimsonweed, Kochia,

Lambsquarters, Morningglory (tall, pitted, ivyleaf, entireleaf, smallflower), Mustard,

Nightshade (black, hairy), Pigweed, Carelessweed, Purslane, Florida Pusley, Common

Ragweed, Giant Ragweed, Sicklepod, Smartweed, Bristly Starbur, Common Sunflower,

Velvetleaf, Buttonweed, Waterhemp, Yellow Nutsedge, Amaranths, Milkweed, Russian

Thistle, Canada Thistle, Horseweed, Fleabane, Prickly Lettuce, Hophornbeam copperleaf,

Burcucumber, Yellow Nutgrass, Texasweed, Mexicanweed, Spotted Spurge, Quackgrass,

Wild Poinsettia, Brachiaria, Smooth Brome, Downy Brome, Orchardgrass, Fescue, Perennial

Ryegrass, Wirestem Muhly, Wheat, Corn, Annual Bluegrass, Kentucky Bluegrass, Sorghum,

Alfalfa, Hemp Sesbania, Red Clover, White Clover, Venice Mallow, Sida (prickly, spiny),

Teaweed, Ladysthumb, Curly Dock, Witchweed, Redweed, Common Mullein, Marestail,

Eastern Black Nightshade, Puncturevine. 

Formulation Types Registered:

Technical Grade Active Ingredient 

End Use Products 

C Emulsifiable Concentrate 

C Flowable Concentrate 

C Granular 

C Microencapsulated 

C Soluble Concentrate/Liquid 
4

Multiple Active Ingredient Products Contain:

C 036101 (Trifluralin) 

C 080803 (Atrazine) 

C 103601 (Glyphosate-salt) 

C 128848 (Imazaquin) 

C 080803 + 129043 (Atrazine + Dicamba) 

Method and Rates of Application:

Method and Rate - see Appendix A

Equipment - Aircraft; Boom sprayer; Center pivot irrigation; Granule applicator; Ground;

Pneumatic (compressed air) applicator; Sprayer; Spreader 

Type of Treatment - Band treatment; Chemigation; Conservation tillage; Directed spray;

Soil broadcast treatment; Soil incorporated treatment; Soil treatment;

Spray 

Timing - At planting; Early preplant; Ground-crack; Postemergence; Postplant;

Posttransplant; Preemergence; Preplant 

c. Estimated Usage of Pesticide

This section summarizes the best estimates available for the pesticide uses of alachlor. These

estimates are derived from a variety of published and proprietary sources, as well as USDA and State

statistics that are available to the Agency. The data, reported on an aggregate and site (crop) basis,

reflect annual fluctuations in use patterns as well as the variability in using data from various

information sources.

Table 1 below summarizes the pesticide's use by site. 

Table 1: Percent of Various U.S. Crops Treated Annually with Alachlor, 

1993 - 1995

Site/1 Acres

Grown

/2 (X 000)

Acres Treated

 (X 000)/3

Percent

Crop

Treated

Pounds AI

 Applied (X 000)

Major Region

 or State

Beans, Dry 1,826 150 - 170 <10 270 - 330 Nationwide

Beans, Succulent 44 5 - 15 10 - 35 15 - 25 CA and ID

Corn, Sweet 763 235 - 250 30 - 35 400 - 500 Nationwide
Table 1: Percent of Various U.S. Crops Treated Annually with Alachlor, 

1993 - 1995

Site/1 Acres

Grown

/2 (X 000)

Acres Treated

 (X 000)/3

Percent

Crop

Treated

Pounds AI

 Applied (X 000)

Major Region

 or State

5

Corn, Field 77,235 15,000 - 20,000 20 - 25 20,000 - 30,000 Nationwide

Ornamentals 597 15 - 20 <5 20 - 25 Southeast

Peanuts 1,688 20 - 30 <5 100 - 150 Southeast

Sorghum 10,944 1,050 - 1,450 10 - 15 1,500 - 2,500 Nationwide

Soybeans 60,418 4,000 - 6,000 5 - 10 7,000 - 11,000 Nationwide

Sunflowers 2,837 20 - 30 <1 - 1 20 - 40 SD and NE

Totals 20,495 - 27,965 29,325 - 44,570

/1 - Site identification based on REFS.

/2 - Acres grown based on USDA, Agricultural Census, and state statistics.

/3 - Acres treated represents the number of acres treated times the number of applications.

d. Data Requirements

Data requested in the 1984 Registration Standard for alachlor include studies on product

chemistry, environmental fate, toxicology and residue chemistry. Pursuant to FIFRA, Data Call-In

Notices (DCIs) were issued on June 9, 1986, (required the submission of residue chemistry data),

June 18, 1986, (required the submission of use and exposure data pertaining to the ground and

surface water studies), August 28, 1991, (required the submission of ecological effects, residue

chemistry and environmental fate studies), and October 13, 1995, (required the submission of

exposure data). These data were required to support the uses listed in the Registration Standard.

Appendix B includes all data requirements identified by the Agency for currently registered uses

needed to support reregistration.

e. Regulatory History

Alachlor was registered in 1969 as a selective herbicide for control of broadleaf weeds and

grasses. In the US, technical alachlor alachlor is produced by Monsanto Company. There are 12

active products and one 24(c) registration. Monsanto has ten active products and American Cyanamid

has two active products.

A Registration Standard was issued for alachlor on November 20, 1984. The Registration

Standard stated that (1) alachlor was classified as an oncogen and therefore subject to the Agency’s

requirement that it be considered for Special Review, (2) that the Agency would not approve any

new uses for alachlor during the period of the Special Review, and (3) that alachlor appeared to leach

through the soil and had been found in groundwater. Monsanto voluntarily removed the use of
6

alachlor on potatoes. Several label restrictions were required to mitigate risk from alachlor. These

restrictions included: the use of protective clothing, a tumor hazard warning statement, a water

contamination warning statement, prohibition of aerial application, and handling instructions to reduce

applicator exposure. A special information and training program available to all users of alachlor was

required. 

The Registration Standard required additional data on the leaching and mobility of alachlor

to examine the potential of alachlor to contaminate ground and surface water. A monitoring study

of ground and surface water was required. Additional studies were also required in the areas of

toxicology, product chemistry, and residue chemistry.

Alachlor has been the subject of previous Agency regulatory action. On January 9, 1985, the

Agency published a Notice of Initiation of Special Review of Registrations of Pesticide Products

Containing Alachlor (Federal Register, Volume 50, No. 1115) and issued the Alachlor Position

Document (PD-1) the document detailing the basis for the Special Review. The Special Review was

initiated under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) because pesticide

products containing alachlor met or exceeded the Agency’s then applicable oncogenicity criteria at

40 CFR 162.11 (a)(3). Specifically EPA determined that exposure to pesticide products containing

alachlor resulted in the increased incidence of tumors at multiple sites in two species of laboratory

animals (mice and rats). Subsequently, the risk criteria in 40 CFR 162.11 were superceded by revised

criteria set forth in 40 CFR 154.7 (a) (2). The Agency determined that alachlor exceeded the revised

criteria for oncogenicity, which is now referred to as carcinogenicity, as well. 

Following the review of public comments and additional information received in response to

the Notice of Initiation of Special Review and the Alachlor PD-1, EPA issued a Notice of Preliminary

Determination on October 8, 1986 (Federal Register, Volume 51, No. 36106). In this notice the

Agency announced its proposed decision to allow the continued use of alachlor products subject to

modifications of the terms and conditions of registration. This notice also announced the availability

of the Alachlor Technical Support Document (TSD) which detailed the basis for the Agency`s

Preliminary Determination. The TSD was a detailed discussion of the risk and benefit data considered

by EPA. These documents were distributed in accordance with Sections 8 and 25 of FIFRA and sent

to all registrants and applicants for registrations of alachlor products.

In the Preliminary Notice the Agency proposed to reclassify alachlor as a restricted use

pesticide, to require the use of a closed mixing/loading system whenever alachlor was applied to 300

acres or more, to allow aerial applications of alachlor but prohibit the use of human flaggers, and to

retain the tumor warning on labels. In addition, pursuant to 40 CFR 162.17, EPA notified producers

of all alachlor products registered solely for intrastate sale and distribution, that they were required

to submit complete applications for registration. In response to the Preliminary Notice, the registrant

provided additional residue data that indicated that residues in lima beans and dry beans were lower

than previously estimated. The registrant also agreed to remove green peas from the labeling.

Following review of comments and additional information received in response to the
7

Preliminary Notice, EPA issued a notice entitled “Alachlor; Notice of Intent to Cancel Registrations,

Conclusion of Special Review on December 31, 1987 (Federal Register, Volume 52, No. 49480).

This notice, known as the Alachlor Position Document 4 (PD-4) concluded the Special Review, and

stated that EPA would cancel the registrations and deny applications for registration of products

containing alachlor that did not comply with the terms and conditions of registration set forth in the

PD-4. The PD-4 stated that tolerances would be rewritten once all residue data required by the

Registration Standard were received and evaluated. The PD-4 required the following label

amendments; Restricted Use due to Oncogenicity, a tumor hazard warning, and use of mechanical

transfer systems by mixer/loaders and/or applicators who treat 300 acres or more annually. Human

flaggers were prohibited during aerial application. Labeling bearing required changes was submitted

and accepted in early 1988. 

The Notice of Final Determination stated that the available data were adequate for

demonstrating alachlor’s potential to contaminate ground water. However, the available data were

considered to be inadequate for a risk assessment considering the inadequate representation of

alachlor’s use in terms of geographic area and associated hydrogeologic conditions. Thus, this issue

was deferred pending completion of the National Alachlor Well Water Survey (NAWWS). As

discussed in this RED, the Agency has received and reviewed the NAWWS data. It was one of the

studies relied on in determining quantitative drinking water risks. The other commitment made in the

PD-4 was “to revisit the risk and benefits of alachlor on a crop-by-crop basis.” Since the dietary

risks, considering both food and water, for chronic and carcinogenic risks are not of concern, the

Agency will not perform a risk/benefit analysis.

In 1996 the Food Quality Protection Act of 1996 (FQPA) was signed into law. Since FQPA

requires the Agency to consider the potential for cumulative effects from alachlor and other

compounds with a common mechanism of toxicity, Monsanto has submitted its assessment of the

common mechanism of alachlor with other pesticides. Additionally, based on the results of the

Agency’s Cancer Peer Review, Monsanto petitioned for removal of the Restricted Use classification

of alachlor.

III. SCIENCE ASSESSMENT

a. Physical Chemistry Assessment

Technical alachlor is a colorless to white crystalline solid with a melting point of 39.5-41.5

oC and a specific gravity of 1.133 g/mL at 25 oC. At 25 oC alachlor is soluble in water at 242 ppm.

Alachlor is soluble in ether, acetone, benzene, alcohol, and ethyl acetate, and is slightly soluble in

hexane. The following figure shows the chemical structure of alachlor.
8

N

CH3

H C3

O

Cl

O

CH3

Empirical Formula: C14H20NO2Cl

Molecular Weight: 269.77

CAS Registry No.: 15972-60-8

Shaughnessy No.: 090501

b. Human Health Assessment

1. Toxicology Assessment

Toxicology data are used to assess the hazards to humans and domestic animals. The data are

derived from a variety of acute, subchronic, and chronic toxicity tests; developmental/reproductive

tests; and tests to assess mutagenicity and pesticide metabolism. Reregistration eligibility decisions

require that the Agency have sufficient information to select the appropriate end-points for

performing a human health risk assessment. This requires a toxicological database that is not only

complete, but of acceptable quality.

The toxicological data base on alachlor is adequate and will support reregistration eligibility.

 (See Table 2)

Table 2: Alachlor Toxicological Database

Guideline Study Type MRID No. Required? Satisfied?

OPPTS GLN

870.1100

(formerly 81-1)

Acute oral toxicity

- rat

00139383 yes yes

OPPTS GLN

870.1200

(formerly 81-2)

Acute dermal

toxicity - rabbit

00139384 yes yes
Table 2: Alachlor Toxicological Database

Guideline Study Type MRID No. Required? Satisfied?

9

OPPTS GLN

870.1300

(formerly 81-3)

Acute inhalation

toxicity - rat

00109561 yes yes

OPPTS GLN

870.2400

(formerly 81-4)

Primary eye

irritation - rabbit

00139385 yes yes

OPPTS GLN

870.2500

(formerly 81-5)

Primary dermal

irritation - rabbit

00139386 yes yes

OPPTS GLN

870.2600

(formerly 81-6)

Dermal

sensitizationguinea pig 

00161728 yes yes

OPPTS GLN

870.3100

(formerly 82-1a)

Subchronic oral

toxicity - rat

00023658 yes no

(satisfied by

83-1a)

OPPTS GLN

870.3150

(formerly 82-1b)

Subchronic oral

toxicity - dog

00087479 yes yes

OPPTS GLN

870.3200

(formerly 82-2)

21-day dermal

toxicity - rabbit

00147328 yes yes

OPPTS GLN

870.4100

870.4200

870.4300

(formerly 83-1a,

83-2a, 83-5)

Chronic oral

toxicity/

carcinogenicity -

rat or Combined

chronic toxicity/

carcinogenicity

00091050,

00139021,

00141060

yes yes

OPPTS GLN

870.4100

(formerly 83-1b)

Chronic oral

toxicity - dog

00148923 yes yes

OPPTS GLN

870.4200

(formerly 83-2b)

Carcinogenicity -

mouse

00075709,

43507601

yes yes
Table 2: Alachlor Toxicological Database

Guideline Study Type MRID No. Required? Satisfied?

10

OPPTS GLN

870.3700

(formerly 83-3a)

Teratology - rat

Prenatal

developmental

toxicity

00043645 yes yes

OPPTS GLN

870.3700

(formerly 83-3b)

Teratology - rabbit

Prenatal

developmental

toxicity

40579402 yes yes

OPPTS GLN

870.3800

(formerly 83-4)

Multi-generation

reproduction - rat

Reproduction and

fertility effects

00075062 yes yes

OPPTS GLN

870.5300

870.5385

870.5500

870.5550

870.5575

(formerly 84-2,

84-4)

Mutagenicity -

various assays

00109563,

00141061,

00141062,

00149821

yes yes

OPPTS GLN

870.7485

(formerly 85-1)

General

metabolism - rat

Metabolism and

Pharmacokinetics

00132045 yes yes

OPPTS GLN

870.7600

(formerly 85-3)

dermal penetration

(absorption)

00149403,

00149404,

00149405

yes yes

a. Acute Toxicity

Data from acute toxicity studies serve as the basis for labeling and packaging requirements.

Acute toxicity studies with alachlor indicate low toxicity. Table 3 below summarizes the available

information on the acute toxicity of alachlor.
11

Table 3: Acute Toxicity of Alachlor

GLN

 No.

Study Type 

(%a.i.)

MRID No. Results Toxicity Category

870.1100 Acute Oral

(92.8%)

00139383 LD50 = 930 mg/kg III

870.1200 Acute Dermal

(90.0%)

00139384 LD50 = 13.3 g/kg IV

870.1300 Acute Inhalation

(95.3%)

00109561 LC50 > 1.04 mg/L

 (4 hours)

III

870.2400 Primary Eye 

Irritation

(92.8%)

00139385 No significant irritation IV

870.2500 Primary Skin

Irritation

(92.8%)

00139386 No significant irritation IV

870.2600 Dermal Sensitization

(94.5%)

00161728 Sensitizer N/A

The oral LD50 for alachlor in a rat study was 930 (810-1050) mg/kg (MRID No. 00139383).

Clinical signs observed after oral dosing included ataxia, muscle tremors, hyperactivity, lethargy,

dyspnea, and convulsions. The LC50 for rat inhalation was 1.04 mg/L for 4 hours. Clinical signs

were related to eye and nasal irritation (MRID No. 00109561). 

Alachlor has been shown to be a skin sensitizer in guinea pigs (MRID No. 00161728). Alachlor

was also a skin sensitizer in a repeated insult patch test in humans (MRID No. 00023611, 00023612).

b. Subchronic Toxicity

In an IBT (Industrial Biotest) subchronic toxicity study (MRID No. 00023658), male and

female Charles River albino rats from Charles River Breeding Laboratories, Inc., North Wilmington,

MA received 0, 20, 200, or 2000 ppm CP50144 technical alachlor which is 0, 1.5, 15, or 146

mg/kg/day for the control, low, mid and high dose groups, respectively by standard conversion

factors for 90 days. Systemic toxicity was noted in the high dose animals as decreased body weights

and body weight gains, decreased food consumption and efficiency, increased absolute and relative

spleen weights, increased relative liver weights, increased relative to body weight kidney weights, and

decreased relative gonad weights (testis and ovaries). The systemic toxicity NOEL (No Observed

Effect Level) is 15 mg/kg/day. The systemic toxicity LOEL (Lowest Observed Effect Level) is 146

mg/kg/day based on decreased body weights, body weight gains, reduced food consumption,
12

increased spleen, liver and kidney weights, and decreased gonad weights. This study is classified as

unacceptable since it is an invalidated IBT study. Guideline requirements are not satisfied.

However, this study was not repeated since an adequate chronic toxicity study was performed by the

registrant.

In a subchronic feeding study, Beagle dogs were administered doses of 0, 5, 25, 50, or 75

mg/kg/day of alachlor (93.3% a.i.; Lot No. MTLT 1128X) in capsules for six months. Systemic

toxicity was noted as an increase in liver weights at the lowest dose tested (LDT; 5 mg/kg/day) and

above in males, and at 25 mg/kg/day and above in females. An increase in the incidence of gross

pathological observations (discoloration of the liver and biliary hyperplasia) in the liver were noted

at 25 mg/kg/day and above in both sexes. Dose related body weight gain decrement, reduction in

total serum protein levels, globulin levels, increase in Serum AP (alkaline phosphatase), LDH (lactate

dehydrogenase) and occasionally SGPT (serum glutamic-pyruvic transaminase) activities in both

sexes were noted at 25 mg/kg/day and above. Increased incidence of emaciation and mortality were

noted at 50 mg/kg/day and above. The systemic toxicity NOEL could not be determined, but would

be less than 5 mg/kg/day (LDT). The systemic toxicity LOEL is equal to or less than 5 mg/kg/day

based on increased liver weight (MRID No. 00087479). 

In a 21-day dermal toxicity study, alachlor (EC MCB/C9; Lot# MDLL0407B, 45.3% a.i. and

Lot# MDLL0429B, 45.2% a.i.) was administered to New Zealand white rabbits at dose levels of 0,

50, 300, or 1000 mg/kg. Repeated exposure resulted in skin damage ranging from dermal irritation

to corrosion. The observations occurred in a dose-related manner. Systemic toxicity was noted as

an increase in polymorphonuclear leukocytes which may have resulted from the presence of the

chronic inflammatory reaction in the dermis. There was also a significant (p < 0.01) decrease in body

weight in both sexes at the high dose. There was also regenerative anemia, with an elevated white

blood cell count, and platelet counts, and a decreased albumin/globulin ratio. Also, there was

evidence of liver glycogen depletion at the high dose. Three animals in the mid dose and 6 animals

in the high dose died or were sacrificed in extremis. The cause of death may be related to bacterial

pneumonia due to bacteria entering through damaged skin.

The systemic toxicity NOEL is 50 mg/kg/day. The systemic toxicity LOEL is 300 mg/kg/day

based on hematological and clinical chemistry changes. The dermal toxicity NOEL could not be

determined, but would be less than 50 mg/kg/day. The dermal toxicity LOEL is equal to or less than

50 mg/kg/day due to skin damage (MRID No. 00147328).

c. Chronic Toxicity and Carcinogenicity

In a one-year study in beagle dogs, alachlor technical (94.1% a.i.; Lot# MULT 0417B) was

given by capsule at doses of 0 (control), 1.0, 3.0, or 10 mg/kg/day. Systemic toxicity was noted at

the 3 mg/kg/day dose as hemosiderosis in the kidney of one male dog and in the spleen of another

male dog; and at the high dose as hemosiderosis and hemolytic anemia in the liver of males (3/6). The

systemic toxicity NOEL is 1 mg/kg/day. The systemic toxicity LOEL is 3 mg/kg/day based upon

signs of hemosiderosis and hemolytic anemia (MRID No. 00148923).
13

In a two-year feeding study, Long-Evans rats received doses of 0, 100, 300, or 1000 ppm

(approximately 0 (control), 14, 42, or 126 mg/kg/day) technical alachlor in the diet for approximately

117 weeks in males (812 to 813 days) and 106 weeks in females (741 to 744 days). It should be

noted that the test substance used for the first 11 months of the study was stabilized with 0.5%

epichlorohydrin (Lot # XHI-167, 92.6% a.i.), while the test substance used for the remaining 16

months of the study was stabilized with epoxidized soybean oil (Lot # MHK-6, 92.19% a.i.).

Epichlorohydrin is carcinogenic for male Wistar rats and Sprague-Dawley rats: when given in

drinking water epichlorohydrin has been found to cause forestomach tumors (squamous cell

papillomas and carcinomas) in male Wistar rats (Konishi et al. Gann 71:922-923, 1980). By the

inhalation route epichlorohydrin has been found to cause squamous carcinomas of the nasal cavity

(Laskin, et al. J. Natl. Cancer Inst. 65:751-755, 1980). The effect of epichlorohydrin on tumor

formation in this study is not known.

 

Systemic toxicity was noted at 14 mg/kg/day and above as ocular lesions in the form of uveal

degeneration syndrome, and as increased thyroid weights in both sexes; and as increased liver weight

in the high dose groups. These observations were correlated with degenerative liver changes at all

dose levels. There were decreased body weights in the mid and high dose males and the high dose

females during the second year of the study. Statistical evaluation of mortality indicated an increasing

trend for male and female rats with increasing doses. Male rats had an increased incidence of nasal

respiratory epithelium adenomas, and adenomas and/or adenocarcinomas combined at 42 and 126

mg/kg/day (p < 0.01 and significant trends). Also, there was increased incidence in malignant mixed

gastric tumors and gastric adenocarcinomas and/or malignant mixed gastric tumors combined at 126

mg/kg (p < 0.01 and significant trends). There were increased incidences in thyroid follicular cell

adenomas and adenomas and/or carcinomas combined at 126 mg/kg (p < 0.01 and significant trends).

There were increased incidences in the 126 mg/kg/day dose group for stomach osteosarcomas, and

thyroid follicular cell carcinomas (both at p < 0.05). There were increased incidences of brain

oligodendrogliomas of the hypothalamus, stomach osteosarcomas, and thyroid follicular cell

carcinomas (all at p < 0.01) and significant trends. For female rats there was increased incidence of

nasal turbinate adenomas, and adenomas and/or adenocarcinomas combined at 42 (p < 0.05) and 126

(p < 0.01) mg/kg/day and significant trends for these tumor types. There was also an increased

incidence of malignant mixed gastric tumors, and gastric adenocarcinomas and/or malignant mixed

gastric tumors combined (p < 0.01) at 126 mg/kg/day, as well as significant trends for these tumor

types. Also, increased incidence at 14 and 126 mg/kg/day of mammary gland adenofibromas,

adenofibromas and/or fibroadenomas combined, and adenofibromas, fibroadenomas, and papillary

adenocarcinomas combined (p < 0.05). There were significant increasing trends in liver adenomas,

stomach osteosarcomas, and thyroid follicular cell adenomas and/or adenocarcinomas combined (all

at p < 0.01). Of all the tumors listed above, the increasing trend observed in brain

oligodendrogliomas of the hypothalamus, and the significant trend in brain ependymomas and

ependymomas and/or malignant ependymomas combined in male rats and the significant pair-wise

comparisons for mammary gland adenofibromas, adenofibromas and/or fibroadenomas combined, and

adenofibromas, fibroadenomas, and papillary adenocarcinomas combined and liver adenomas in

female rats were considered to have occurred at excessively toxic doses, and only the tumors of the

nasal epithelium, stomach, and thyroid were treatment related and are the basis for considering
14

alachlor to be carcinogenic in the rat. The systemic toxicity NOEL could not be determined but

would be less than 14 mg/kg/day. The systemic toxicity LOEL is equal to or less than 14 mg/kg/day

based on ocular lesions (uveal degeneration syndrome) and hepatic toxicity (MRID No. 00091050).

In a second long-term study, Long-Evans rats were fed doses of 0, 0.5, 2.5 or 15 mg/kg/day

technical alachlor (94.13%; Lot# MULT 0417B; stabilized with 1.28% epoxidized soybean oil) for

110 weeks (25 to 26 months). Systemic toxicity was noted at 15 mg/kg/day, highest dose tested

(HDT), as molting of the retinal pigmentation (uveal degeneration syndrome), increased mortality rate

(significant increasing trend) in females (no effect in males) and abnormal disseminated foci in male

livers. Male rats had increased incidence of nasal respiratory epithelium adenomas at 15 mg/kg/day

(p < 0.01 with significant trend). Female rats had an increased incidence of adrenal benign

pheochromocytomas and nasal respiratory epithelium adenomas at the 15 mg/kg/day dose level (p

< 0.05 and p < 0.01, respectively and significant trend). There was also increased incidence of

thymus malignant lymphosarcomas at the 15 mg/kg/day dose level (p < 0.05); however, only the

tumors of the nasal epithelium were treatment related and are the basis for considering alachlor to be

carcinogenic in the rat. The systemic toxicity NOEL is 2.5 mg/kg/day and the systemic toxicity

LOEL is 15 mg/kg/day, based on molting of retinal pigmentation and increased mortality in females,

with abnormal disseminated foci of the liver in males (MRID No. 00139021). 

In a special two-year study, technical alachlor (94.13% a.i.; Lot# MULT-0417B; stabilized with

1.28% epoxidized soybean oil) was administered in the diet at 126 mg/kg/day to Long-Evans rats for

two years to assess ocular effects of the compound (uveal degeneration syndrome). It was observed

that females were more sensitive than males, and that once the uveal degeneration syndrome was

observed, it was irreversible (a group exposed to alachlor for the first 5 to 6 months). The nasal,

thyroid and gastric tumors observed in earlier investigations were observed. The nasal tumors were

noted at the end of the study (2 years) in the group that was exposed to alachlor for the first 5 to 6

months (MRID No. 00141060). 

In a carcinogenicity study, technical (alachlor; Lot# XHI-167, 92.6% a.i.; Lot# MHK-6,

92.19% a.i.) stabilized with epichlorohydrin at the start of the study (for 11 months) and then with

a lot stabilized with epoxidozed soybean oil was given to CD-1 albino mice in the diet for 18 months

at doses of 0 (control), 26, 78 or 260 mg/kg/day. Systemic toxicity was noted in the mid and high

dose groups as increased liver weights, increased kidney weight in the mid and high dose males, and

in the high dose females as reduced survival (statistical evaluation of mortality showed no significant

incremental changes with increasing doses of alachlor in male mice while female mice showed a

significant increasing trend in mortality with increasing doses of alachlor) and body weight gains

(10%), males were not similarly affected. Thyroid follicular atrophy was noted in the mid and high

dose males and the high dose females. There was an increase in water consumption in the high dose

groups. Males had a significant increasing trend in bronchioalveolar adenomas at p < 0.05. There

were no significant differences in the pair-wise comparisons of the male dosed groups with the

controls. Female mice had significant increasing trends, in addition to significant differences in the

pair-wise comparisons of the 260 mg/kg/day dose group with the controls, for bronchioalveolar

adenomas and adenomas and/or carcinomas combined, all at p < 0.01 (MRID No. 00075709). 
15

In a second carcinogenicity study, CD-1 albino mice (60 animals/sex/dose) from Charles River

Laboratory (Portage MI) received 0 (control), 100, 400 or 1600 ppm (male: 0, 16.64, 65.42, or

262.40 mg/kg/day; and female: 0, 23.73, 90.34, or 399.22 mg/kg/day respectively, calculated directly

from food consumption data) of alachlor (94.64% a.i.; Lot# MUS-9107-3181-T) in the diet for 18

months. Ten animals/ sex/ dose were sacrificed at 12 months. Systemic toxicity was noted in high

dose males as lower body weight gains for the period ending on day 91; high dose males and females

with lower body weight gains for the period ending on day 372 and high dose females with lower

body weight gains to the end of the study. There were no decreases in food consumption, rather

there were increases in high dose females. No treatment related effects on food efficiency were noted

in the treated males; however, the high dose females had a dose related decrease in food efficiency

at 12 and 18 months. 

Gross pathological observations included (at 18 months) a mass/nodule of the liver as noted

in 6/41, 7/40, 10/41, and 10/41 in males and 1/40, 0/42, 1/36, and 3/40 in females for the control,

low, mid and high dose groups, respectively; a mass/nodule of the lung in 3/41, 9/40, 10/41, and

12/41 in males and 1/40, 2/42, 9/36, and 6/40 in females for the control, low, mid and high dose

groups, respectively. There was a statistically significant increase in absolute liver weights of the low

and high dose females and liver weights relative to brain weights in high dose females at 12 months.

Also, there was an increase in relative liver weights in high dose females at 18 months. The high dose

males showed a statistically significant increase in absolute and relative liver weights at 18 months.

There was a statistically significant decrease in kidney weights relative to body weights in high dose

females at 12 months and a decrease in absolute kidney weight in high dose females at 18 months.

The males at 18 months had a significant increase in absolute kidney weights in all dose groups,

increased kidney weights relative to body weights in the low and high dose groups and increased

kidney weights relative to brain weight in the mid and high dose groups. 

Non-neoplastic observations included slight increases in tubular epithelium

hyperplasia/regeneration in the kidney(s) of high dose males, an increase in centrilobular

hepatocellular hypertrophy in mid and high dose males along with an increase in high dose females

of fibrous osteodystrophy of the sternum. Neoplastic observations included an increase in

bronchoalveolar adenomas in all treated groups in males (7, 18, 27, and 22%, for the control, low,

mid and high dose groups, respectively) and females (5, 14, 10, and 17% for the control, low, mid

and high dose groups, respectively), statistical significance was achieved in mid dose males. The

combined incidence of bronchoalveolar adenomas/carcinomas was increased in all treated groups in

males (7, 18, 32, and 22% for the control, low, mid and high dose groups, respectively). Only the

mid dose males were statistically significantly different from the controls. 

These data indicate that CD-1 mice showed evidence of bronchoalveolar adenomas (mostly)

and/or carcinomas in the lung, but the data were considered to be inconclusive in terms of the

relationship to alachlor treatment especially when both mouse carcinogenicity studies are considered

together. The systemic toxicity NOEL for males is 16.64 mg/kg/day and the systemic toxicity LOEL

for males is 65.42 mg/kg/day based on an increase in centrilobular hepatocellular hypertrophy in mid

and high dose males. The systemic toxicity NOEL for females is 90.34 mg/kg/day and the systemic
16

toxicity LOEL for females is 399.22 mg/kg/day based on body weight gain decrements and an

increase in fibrous osteodystrophy of the sternum. (MRID No. 43507601).

d. Developmental Toxicity

Developmental studies are designed to identify possible adverse effects on the developing

organism which may result from the mother’s exposure to the pesticide during pre-natal development.

In a developmental toxicity (teratology) study, Charles River rats were given 0 (control), 50,

150 or 400 mg/kg/day of alachlor (92.19% a.i.; Lot# MHK-6) by gavage on gestation days 6 through

19, inclusive. Maternal systemic toxicity was noted at the high dose as maternal deaths, and

increased incidence of soft stools, red matter around the nose and mouth and anogenital staining and

reduced body weight gains. Developmental toxicity was noted at the high dose as a slight increase

in the mean number of early and late resorptions with related increased post-implantation loss and a

slight reduction in the mean number of viable fetuses. The maternal toxicity NOEL is 150 mg/kg/day.

The maternal toxicity LOEL is 400 mg/kg/day based on increased mortality, increased incidence of

clinical signs and reduced body weight gains. The developmental toxicity NOEL is 150 mg/kg/day.

The developmental toxicity LOEL is 400 mg/kg/day based on increased resorptions and decreased

litter size (MRID No. 00043645). 

In a developmental toxicity study, New Zealand white rabbits received doses of 0 (control), 50,

100 or 150 mg/kg/day alachlor (94.7% a.i., Lot# 51486-C) by gavage on days 7 through 19,

inclusive. Maternal systemic toxicity was noted at the high dose as decreased body weight gain

during the dosing period followed by a rebound in body weight gain during the period following

dosing. No developmental toxicity was noted in the parameters measured. The maternal toxicity

NOEL is 100 mg/kg/day. The maternal toxicity LOEL is 150 mg/kg/day based upon a reduction in

body weight gains. The developmental toxicity NOEL is equal to or greater than 150 mg/kg/day

(highest dose tested) and the developmental toxicity LOEL is greater than 150 mg/kg/day (MRID

No. 40579402).

e. Reproductive Toxicity

A reproduction study is designed to provide general information concerning the effects of a test

substance on mating behavior, conception, parturition, lactation, weaning, and growth and

development of the offspring.

In a three-generation reproduction study, Sprague Dawley CD rats received either 0 (control),

3, 10, or 30 mg/kg/day technical alachlor (92.6% a.i.; Lot# XHI-167) in the diet. Parental/ Offspring

systemic toxicity was noted at the high dose in the form of discoloration of the kidney and reduced

kidney weights (especially in F2 parents and F3b pups). Histopathology revealed chronic nephritis in

the high dose males. The high dose females of each parental generation and the F3b females had lower

ovary weights (this decrease was maximal (17%) and significant in the Fo generation, and was also

associated with 17% decrease in the ovaries to body weight ratio). No microscopic changes were
17

reported in the ovaries and no effect was noted on reproductive parameters. The parental/offspring

systemic toxicity NOEL is 10 mg/kg/day. The parental/offspring systemic toxicity LOEL is 30

mg/kg/day based on kidney effects. Since there were no effects on reproductive parameters, the

reproductive toxicity NOEL is equal to or greater than 30 mg/kg/day (HDT). The reproductive

toxicity LOEL is greater than 30 mg/kg/day. (MRID No. 00075062).

f. Mutagenicity

 Alachlor

A reverse mutation assay in five strains of Salmonella typhimurium (TA1535, TA100, TA1537,

TA1538, and TA98) using 10 to 5000 Fg/plate with and without S9 metabolic activation was

negative (MRID No. 00109563).

An E. coli WP2 hcr reverse mutation assay using 10 to 5000 Fg/plate with and without S9

metabolic activation was negative (MRID No. 00109563). 

A rec assay with Bacillus subtilis (H17 and M45) using 20 to 2000 Fg/disk was negative

(MRID No. 00109563). 

Alachlor was positive in an in vivo/in vitro unscheduled DNA synthesis (UDS) assay at 1000

mg/kg, a dose approximating the LD50 in rats. Doses tested were 50, 200, and 1000 mg/kg with

evaluations at 2 and 12 hours (MRID No. 00141061). 

An assay of structural chromosomal aberrations (e.g., in vivo cytogenetics in rat bone marrow)

was negative. Single doses of 0, 100, 300, or 1000 mg/kg with sacrifice times of 6, 12, 24, and 48

hours (MRID No. 00141062). 

A CHO (Chinese hamster ovaries) HGPRT mammalian cell forward mutation test was negative.

Dose levels tested were 15 to 150 Fg/ml without S9 metabolic activation and 15 to 330 Fg/ml with

S9 metabolic activation (MRID No. 00148921). 

Alachlor was negative in an Ames Salmonella typhimurium mammalian microsome plate

incorporation assay, conducted in the absence of S9 and with S9 prepared from uninduced rat,

mouse, or monkey nasal turbinates, at concentrations ranging from 50 to 5000 Fg/plate. Tester

strains TA98, TA100, TA1535, and TA1537 were used (MRID No. 42651301).

Alachlor was positive for inducing UDS in hepatocytes recovered from male Fischer-344 rats

at 12 hours after oral gavage administration of 1000 mg/kg. (It is noted that the dose at which a

positive response was observed approximates the LD50 of alachlor in rats.) The average number

of net nuclear grains counts were increased by >5 compared with the controls, with > 10% of the cells

in repair (increased net nuclear grains counts over control were obtained with 2/5 animals, and

increases of >5 net grains were observed with 3/5 animals. Similarly, a comparison of the individual
18

data from treated animals and the vehicle control group showed that hepatocytes recovered from 3

of 5 animals were positive for UDS, cells from one animal showed a borderline positive response, and

liver cells from the remaining animal was negative. These data are suggestive of a genotoxic

response. There was no indication of UDS activity at 12 hours after oral gavage administration of

lower doses (50, 200, or 500 mg/kg) or at 2 hours following gavage with 1000 mg/kg (MRID No.

42651302).

Alachlor was negative in a micronucleus assay in Long-Evans rats conducted with a single

intraperitoneal injection of 150, 300, or 600 mg/kg and 24-, 48-, and 72-hour sacrifice times. Two

males and one female receiving the high dose died, and clinical signs of toxicity were observed in

males at all doses and in mid- and high-dose females. A separate experiment in the same study with

radiolabeled alachlor provided evidence that the test material reached the target organ, bone marrow,

when administered intraperitoneally. (MRID No. 42651303).

In a mouse micronucleus assay (MRID No. 44032103), groups of 10-15 male CD-1 mice

received single oral gavage administrations of 250, 500 or 1000 mg/kg alachlor (>99%). The test

material was delivered to the animals in corn oil. Animals were sacrificed at 24 and 48 hours postadministration; bone marrow cells were harvested and 2000 polychromatic erythrocytes per male

were examined for the incidence of micronucleated polychromatic erythrocytes (MPEs). Death and

other clinical signs (i.e., piloerection and/or decreased defecation) were observed at the highest dose

tested. Cytotoxicity for the target organ was not observed at any dose. The positive control induced

the expected high yield of MPEs in the treated males. There was, however, no evidence that alachlor

induced a clastogenic or aneugenic effect at any dose or sacrifice time. The study contained major

guideline deficiencies (i.e, use of a single sex, only 5 males/dose/sampling time and no 72-hour posttreatment sacrifice). However, the study is classified as acceptable for the following reasons: 

@ Previous studies have shown that alachlor is not active in the mouse bone marrow

micronucleus assay.

@ Adequate justification for the use of males only was provided.

@ Variations within and among treatment groups were minimal; hence, the findings with

the smaller than recommended sample size are considered valid. 

@ The uniformly negative response in conjunction with the absence of an effect on cell

cycling suggest that sampling cells 72 hours after compound administration would not

have altered the outcome of the study.

Based on these considerations, the Agency concluded that the study satisfied the requirements

for 84-2 for in vivo cytogenetic mutagenicity data.

Metabolites of Alachlor

Urine from alachlor treated rats was tested in an Ames Salmonella assay using strains TA98,

TA100, TA1535, and TA1537 in the presence and absence of arochlor 1254-induced mammalian

activation system and/or ß-glucuronidase/sulfatase and dose levels of 0.005 to 0.5 ml/plate. There
19

was a weak mutagenic response in strain TA98 in the presence of ß-glucuronidase. A weak mutagenic

response was also observed in strain TA1537 in the presence of both ß-glucuronidase and metabolic

activation (MRID No. 00155389, 00155392).

Bile from alachlor treated Long-Evans rats tested in an Ames Salmonella assay using strains

TA98, TA100, TA1535, and TA1537 in the presence and absence of arochlor 1254-induced liver

homogenate (S-9) or ß-glucuronidase at dose levels of 0.01 to 0.20 ml/plate was negative under all

conditions (MRID No. 00155389, 00155393). 

Ames Salmonella assays with synthesized metabolites of alachlor using strains TA98, TA100,

TA1535, and TA1537 at dose levels of 0.004 to 10.00 mg/plate both with and without S9 metabolic

activation showed that of five metabolites tested (t-hydroxysulfone [CP101394; rat, mouse, goat, hen,

rotation crops metabolite], sec- amide p-hydroxy methylsulfone [CP51214; rat metabolite],

t-sulfinyllacetic acid [CP108267; corn metabolite], t-oxanilic acid [CP108064; soil, water, soybean

metabolite], and t-sulfonic acid [CP108065; corn, soil, soybeans, water metabolite]), only the

t-hydroxysulfone metabolite was observed to be mutagenic (strain TA100 at 3 and 10 mg/plate in the

presence and absence of metabolic activation). (MRID No. 00151394, 00151395, 00151396,

00151397, 00151398, 001513999) 

In Ames Salmonella assays with synthesized metabolites of alachlor (CP97230 and CP101384

[s-hydroxysulfone]) using strains TA98, and TA100 at dose levels of 0.01 to 10.00 mg/plate both

with and without S9 metabolic activation only the s-hydroxysulfone metabolite was observed to be

weakly mutagenic (strain TA100 at 1, 3 and 10 mg/plate in the presence and absence of metabolic

activation). The responses that were less than a 2-fold increase indicating a positive response.

(MRID No. 00155389, 00155391).

Two alachlor metabolites, 2’6’-diethyl-2-methyl thioacetanilide (DMTA) and

2’6’-Diethylaniline (DEA), were tested (MRID No. 42651301) in an Ames Salmonella typhimurium

mammalian microsome plate incorporation assay in the absence of S9 and with S9 prepared from

uninduced rat, mouse, or monkey nasal turbinates. Tester strains TA98, TA100, TA1535, and

TA1537 were used. DMTA was positive in strain TA1535 in three independent Salmonella

typhimurium mammalian microsome plate incorporation assays, conducted with S9 prepared from

mouse nasal turbinates. In addition, there was a tendency for increased numbers of revertants of

TA1535 to occur following exposure to higher dose levels (1500 and/or 5000 Fg/plate) of DMTA.

This was also observed in one of two assays conducted with rat nasal turbinate S9. Although only

marginal increases were observed, the increases were reproducible and statistically significant. There

was no response in tester strains TA98, TA100 or TA1537 with the nonactivated test material or in

the presence of S9 prepared from mouse, rat, or monkey nasal turbinates. However, it should be

noted that DMTA is not a stable product of alachlor metabolism. 

DEA was positive in strains TA1535 and TA100 in at least two independent Salmonella

typhimurium/mammalian microsome plate incorporation assays, conducted with S9 prepared from

mouse nasal turbinates. The nonactivated test material and the test material activated with rat nasal
20

turbinate S9 were also positive in strain TA100. Although only marginal increases were observed,

they were reproducible and statistically significant. There was no consistent response in tester strains

TA98 and TA1537.

g. Metabolism

Metabolism studies in Sprague Dawley rats found that an oral dose of 7 or 700 mg/kg of

alachlor was mainly eliminated in urine and feces, and that 89% of the dose was eliminated in 10 days

(minimal alachlor was found in the expired CO2). The elimination was considered to be biphasic; the

initial rapid phase had a half life of 0.2 to 10.6 hours, which then slowed to a half life of 5 to 16 days.

Fourteen metabolites were identified in urine and 13 in feces. Three of the metabolites were common

to both urine and feces. The eliminated metabolites were conjugates of mercapturic acid, glucuronic

acid, and sulfate (MRID No. 00132045). 

From a metabolism study in Rhesus monkeys, five urinary metabolites were identified after

intravenous injection. One of these metabolites, (also found in rat and mouse urine,

N-[2-ethyl-6-(1-hydroxyethyl)-phenyl]-N-(methoxymethyl)-2(methylsulfonyl)acetamide), tested

positive in the Ames test with Salmonella typhimurium, with and without activation. This metabolite

was an HEEA metabolite not previously identified in the monkey. 

Of the metabolites found in the above two metabolism studies, only two urinary metabolites

were common to both the rat and monkey (secondary and tertiary mercapturic acid conjugates). Side

chain hydroxylation and sulfate conjugation metabolites were not found in monkey urine as they were

in rats (MRID No. 40000901). 

Another metabolism study was conducted on male and female Long Evans rats (MRID

42651306, 42852107, 42651308, 42852108). This study consisted of seven groups of rats. Both oral

dosing studies using corn oil as the vehicle and intravenous administration studies using propylene

glycol as the vehicle were performed. Together these seven studies satisfy GLN 85-1. The study is

considered to be the definitive study for understanding how the rat metabolizes alachlor. 

Oral administration of alachlor was studied using female Long-Evans Crl:CD(LE)BR rats six

to nine weeks of age in five dose groups. Groups 1, 2, and 3 each consisted of 33 rats. Each group

received single oral doses of radiolabeled alachlor (uniformly labeled in the phenyl ring with 14-C,

and enriched with 13-C at the C-2 carbon) at target doses of 7 (Group 1), 70 (Group 2), or 700

(Group 3) mg/kg. Group 4 consisted of 21 rats which received 15 consecutive daily doses of

radiolabeled alachlor at 700 mg/kg/day. Group 5 consisted of 6 rats which received a single oral dose

of radiolabeled alachlor at 700 mg/kg for the purpose of obtaining plasma samples at 2, 4, and 6

hours post-dosing. Long Evans rats (5/sex/dose) were used to study the disposition and metabolism

of alachlor following intravenous administration at 7 (Group 6) or 70 (Group 7) mg/kg. 

In the oral studies, absorption at the 7 or 70 mg/kg dose levels was essentially complete, with

a slight decrease in absorption at the 700 mg/kg dose level. Repeated oral dosing at 700 mg/kg had
21

no significant effect on absorption. Residual radioactivity did not exceed 5% of the administered dose

at any of the dose levels in this study. On a ug/g basis, the residual radioactivity in the non-glandular

stomach was higher than in the glandular stomach except at 4 hours post-dose at the 700 mg/kg dose

level. Decreasing the dose decreased the percentage of the dose in the non-glandular stomach but not

in the glandular stomach. Nasal turbinates showed a secondary peak of radioactivity at 8 hours

post-dose at the 700 or 70 mg/kg dose levels in contrast to other tissues. Excretion of alachlor

derived radioactivity was approximately equivalent between urine and feces, with between 30-47%

excreted in urine and 41-45% excreted in feces at single oral doses of 7, 70, or 700 mg/kg.

Intravenous dosing at 7 or 70 mg/kg resulted in a similar excretion profile. Repeated oral dosing at

700 mg/kg resulted in a slight increase in fecal excretion of radioactivity. In urine, the sec- amide

hydroxymethyl sulfone metabolite (metabolite F5) of alachlor was the predominant urinary metabolite

after oral and intravenous administration, ranging from 2.1-7.4% of the dose. Repeated oral dosing

resulted in the appearance of several additional metabolites, but it is not known whether these

additional metabolites are unique to repeated oral administration of alachlor. In feces, the tert-amide

mercapturic acid and the disulfide appeared to be the major metabolites after single oral doses of

alachlor. Increasing the dose appeared to increase the percentage of these 2 metabolites in feces.

In this study, male and female CD-1 mice (10/sex) received a single oral dose of radiolabeled

alachlor in corn oil (890 mg/kg for male mice, 819 mg/kg for female mice). Urine and feces were

collected daily for up to 7 days post-dose for analysis of excreted radioactivity and for identification

of metabolites. In urine, 18.4 ±3.9% and 23.6±4.1% of the dose was excreted in male and female

mice, respectively. In feces, 66.5±6.9% and 53.6±3.6% of the dose was excreted in male and female

mice, respectively. Total recovery of radioactivity was 85.5±3.7% for male mice, and 79.4±2.7% for

female mice. (The low recoveries may be due to the fact that the mice were housed in pairs in units

larger than those normally used for a mouse.) Analysis of blood at seven days post-dose showed

0.095±0.016% of the dose in males, and 0.075±0.017% of the dose in females. Half life for urinary

elimination was reported as 0.88±0.11 days in males, and 1.18±0.16 days in females. Half-life for

fecal elimination was reported as 0.90±0.06 days in males, and 1.11±0.05 days in females. The data

in this study show that in contrast to the rat, feces is the major route of excretion for alachlor derived

radioactivity in CD-1 mice. The high percentage of fecal excretion could be the result of poor

absorption of test chemical or extensive biliary excretion in the mouse. 

Pooled urine and fecal samples representing the 0-48 hour collection time for urine and the 0-96

hour collection time for feces, were analyzed for metabolites of alachlor in male and female CD-1

mice. In feces, at least 10 metabolites were isolated (See Table 4). Urinary metabolites are in Table

5.
22

Table 4: Metabolites in Mouse Feces 

Metabolite % of Dose - Male Feces % of Dose - Female Feces

alachlor 1.8 2.2

tert-amide mercapturic acid 4.1 3.3

disulfide conjugate 0.6 1.0

sec-amide mercapturic acid 0.7 0.6

tert-amide thioacetic acid 1.2 0.9

tert-amide hydroxy sulfone 0.6 0.5

tert-amide dihydroxysulfone 0.0 0.0

benzyl glucuronide 2.1 1.0

tert-amide cysteine conjugate

+NCH20-glucuronide

5.0 3.7

Table 5: Urinary Metabolites Characterized in the Mouse

Metabolite % of Dose - Male Urine % of Dose - Female Urine

tert-amide cysteine conjugate 0.1 0.3

NCH2O glucuronic acid 1.9 3.2

cysteine sulfoxide (proposed) 0.2 0.3

sec-amide dihydroxysulfone 0.1 0.2

sec-amide hydroxy sulfoxide 0.1 0.2

sec-amide hydroxy sulfone 0.1 0.2

para-amino sulfate 0.1 0.2

While metabolism of alachlor utilizes the same metabolic pathways in mice as in rats, there are

quantitative differences between mice and rats in the metabolite profile present. Mouse feces were

found to contain greater amounts of mercapturic acid conjugate and lesser amount of disulfide

conjugate than in rat feces. The number of urinary metabolites observed in mouse urine was greater

than in rat urine. Mouse urine was found to contain greater amounts of glucuronic acid conjugates

and cysteine conjugates than the rat, but a lesser amount of phenolic (hydroxylated) metabolites
23

(MRID No. 42651305, 42852106).

h. Special Studies

Monsanto has voluntarily submitted a number of special studies on alachlor which were

performed to better understand the mechanisms involved in the toxic responses induced by alachlor,

including tumor formation. The following special studies can be categorized in the following groups:

in vivo metabolism studies, in vitro metabolism studies, whole body autoradiography (WBA) studies,

mutagenicity studies, and cell proliferation/cytotoxicity studies. Some of the submitted data used for

cancer peer review consisted of studies conducted with butachlor, a structural analog of alachlor. 

These special studies do not satisfy any guideline requirements. Further discussion of the conclusions

of these studies is in the Dose Response Assessment Section under the Cancer Classification

discussion.

In Vivo Metabolism Studies

C Effect of Multiple Oral Dosing on the Metabolism, Distribution, and Elimination of Alachlor

in the Long-Evans Rat. (MRID Nos. 42651310, 42852109)

C A Study of the Metabolism and Excretion of Alachlor in Rats Chronically Exposed to Alachlor;

Routes and Rates of Elimination. (MRID No. 42651307) Characterization of Metabolites in

the Urine and Feces. (MRID No. 42931101) 

C Metabolism of Alachlor Methyl Sulfide in Long-Evans Rats. (MRID No. 42651309)

In Vitro Metabolism Studies with Alachlor and Alachlor Metabolites

C A Study of the In Vitro Liver Slice Metabolism of Alachlor in the Male Rat, Mouse, and

Monkey. (MRID No. 42651311)

C A Study of the In Vitro Metabolism of Alachlor Using Enzyme Preparations From Selected Rat

Tissues. Part I. Preparation of Tissue Homogenates. (MRID No. 42651312)

C In Vitro Metabolism of Alachlor by Rat Liver, Kidney, Lung, Nasal, and Stomach

Homogenates. (MRID No. 42852110)

C In Vitro Metabolism of Alachlor by Rat and Mouse Liver and Nasal Enzymes. (MRID No.

42852111) 

C Metabolism of Alachlor Methyl Sulfide in Long-Evans Rats. (MRID No. 42651309)

C In Vitro Metabolism Study of Alachlor, Alachlor Secondary Methyl Sulfide, and

2,6-Diethylaniline by Rat and Monkey Nasal Turbinate Part II. (MRID No. 42651314)
24

C In Vitro Metabolism of Alachlor, Alachlor Secondary Sulfide, Alachlor Sec-Amide, and

2,6-Diethylaniline by Rat and Human Nasal Turbinates and Liver. (MRID No. 43482301)

C Effects of Alachlor on Tissue Levels of Glutathione in the Rat. (MRID No. 42651318)

C Effect of Alachlor on Glutathione Levels of Cultured Adult Rat Hepatocytes. (MRID No.

43641603) (Note: This study was not conducted according to 40 CFR Part 160, but is a report

based on university thesis research conducted at Searle, a Monsanto subsidiary.)

Studies on Alachlor Using Whole Body Autoradiography (WBA)

C Whole Body Autoradiography Studies on 14-C Alachlor in Rats, Mice, and Monkeys. (MRID

No. 42852103)

C A Comparative Study of the Distribution and Localization of Alachlor, Metolachlor, and MON

4601 in Rats Using WBA. (MRID No. 42852104)

C A Study of the Distribution and Localization of Alachlor-Methylsulfide in Rats Using WBA.

(MRID No. 42651304)

C A Study of the Distribution and Localization of Diethylaniline (DEA) in Rats and Mice Using

WBA. (MRID No. 43507401)

C A Study of the Distribution and Localization of Dimethylaniline (DMA) in Rats and Mice Using

WBA. (MRID No. 43706001)

C Comparison of the Distribution and Excretion of Radiolabeled Alachlor in the Sprague-Dawley,

Fisher 344 and Long-Evans Rat and Golden Syrian Hamster. (MRID No. 42852105)

Mutagenicity Studies with Alachlor

C Determination of CP-50144-Derived Radioactivity in Rat. (MRID No. 43369201)

C Study of the Effects of Alachlor on Cellular Stress Response Genes in Rat Nasal Turbinate

Tissue. (MRID No. 43590002)

Cell Proliferation / Cytotoxicity Studies

C Characterization of Covalent Adducts Formed with Nasal Tissue Protein Following Dietary

Administration of 14-C Alachlor to Female Long-Evans Rats. (MRID No. 43641604)

C A Study of the Effect of Alachlor and Selected Metabolites on Cytotoxicity Markers in Nasal
25

Tissue of the Long-Evans Rat. (MRID No. 43641602)

C Gastric Tumor Initiation/Promotion Study of Butachlor in Sprague-Dawley Rats (Monsanto

Company, The Agricultural Group, Environmental Health Laboratory for Monsanto

Company, Monsanto Study#: ML-92-365, Monsanto EHL Study#: EHL 92142, August 18,

1994, MRID No. 43729502). 

C A Study of the Mechanism of Butachlor Induced Carcinogenicity in Female Sprague-Dawley

Rats (Monsanto Company, The Agricultural Group, Environmental Health Laboratory for

Monsanto Company, Monsanto Study#: EHL-92049, Monsanto Study#: ML-92-146,

February 9, 1995, MRID No. 43750801). 

C A Study on the Effect of Butachlor on Cell Proliferation in Selected Tissues of the Mouse

(Monsanto Company, The Agricultural Group, Environmental Health Laboratory for

Monsanto Company, Monsanto Study#: EHL-93064, Monsanto Study#: ML-93-153, August

11, 1994, MRID No. 43729503). 

C Effects of Butachlor on Cell Proliferation and Mucosal Thickness in the Gastric Tissue of

Female Rhesus Monkeys (American Health Foundation and White Sands Research Center and

Environmental Health Laboratory for Monsanto Company, Monsanto Study#: EHL-93064,

Monsanto Study#: WS-93-164 and WS-93-165, MRID No. 43729501). 

C Gastric Tumor Promotion Study of Alachlor in Long-Evans Rats. Monsanto Company, The

Agricultural Group, Environmental Health Laboratory for Monsanto Company, Monsanto

Study No. ML-93-137, Monsanto EHL Study# EHL 93049, February 3, 1995. MRID No.

43590001. 

The data from these studies were used to draw the following conclusions: 

Nasal Tumors

Based upon the available data for alachlor, the following hypothesis has been proposed for

the production of tumors in the nasal mucosa: alachlor is metabolized in the rat to the glutathione

(mercapturic acid) conjugate, which is excreted through the bile into the gut. In the gut, enteric

bacteria metabolize the conjugate to the thiol conjugate, with subsequent S-methylation of the thiol.

This product, the methyl sulfide, is re-absorbed into the systemic circulation where conversion to the

secondary sulfide occurs. Hydrolysis of the secondary sulfide by arylamidase produces the

diethylaniline metabolite of alachlor. Oxidation of the diethylaniline metabolite produces the putative

toxic metabolite, diethylbenzoquinone imine (DEBQI). This metabolite binds to cellular protein,

resulting in eventual cell death. Ensuing regenerative cell proliferation can then lead to neoplasia

through “fixation” of spontaneous mutations. 

The registrant presented data in support of their conclusion that the nasal tumors observed
26

following alachlor administration are unique to the rat based on differences in disposition of alachlor

in the rat versus other species. In vivo studies in Long-Evans rats (MRID No. 42651306, 42651308,

42852107, 42852108) and CD-1 mice (MRID No. 42651305, 42852106) showed that a greater

percentage of a given dose of alachlor was eliminated in feces of mice vs rats. In addition, it was

shown that mouse urine contained a greater percentage of glucuronide conjugates and cysteine

conjugates of alachlor, while rat urine contains a greater amount of phenolic (hydroxylated)

metabolites. In addition, rat feces were found to contain greater percentages of mercapturic acid

conjugates and sulfone metabolites than mouse feces. These data are supportive of the proposed

metabolic pathway for production of the putative toxic intermediate of alachlor in the rat. In addition

to the comparative metabolism of alachlor in rats versus mice, the in vivo metabolism of the methyl

sulfide metabolite of alachlor in female Long-Evans rats demonstrated the production of

4-amino-3,5-diethylphenylsulfate, a stable end-product indicative of the formation of the quinone

imine precursor (MRID No. 42651309). 

In vitro studies conducted by the registrant demonstrated the presence of the reactions

necessary for production of the DEBQI intermediate. These include glutathione conjugation of

alachlor, hydrolysis of the secondary sulfide by arylamidase, and hydroxylation of 2,6-diethylaniline.

Further, in vitro studies demonstrated significant species differences in the rates of these reactions.

Comparative in vitro metabolism of alachlor by several tissues in the Long-Evans rat (MRID No.

42852110) showed the presence of arylamidase activity in liver and nasal tissue resulting in formation

of the 2,6-diethylaniline metabolite. Oxidation of the 2,6-diethylaniline metabolite to

4-amino-3,5-diethylphenol was shown to be approximately 50 times greater in nasal microsomes than

in liver microsomes. Rat and mouse liver and nasal tissues were compared for their ability to

metabolize alachlor to the proposed DEBQI intermediate (MRID No. 42852111). The velocity of

the nasal aryl amidase reaction in rat nasal tissue towards the sec-amide metabolite of alachlor was

observed to be 14-20 times higher in rat than in mouse. The velocity of the nasal arylhydroxylase

towards diethylaniline in rat nasal tissue was found to be approximately 2-fold higher than in mouse.

This study demonstrated that certain key enzymes responsible for production of the proposed toxic

intermediate of alachlor are more active in rat nasal mucosa vs mouse nasal mucosa. Liver and nasal

cytosolic or microsomal fractions were used from rat and monkey to study metabolism of alachlor

to the GSH conjugate, the hydrolysis of alachlor secondary sulfide by arylamidase, and the

hydroxylation of 2,6-diethylaniline (MRID No. 42651314). Velocity of rat liver GST was 3.9 times

greater than monkey GST towards alachlor. Velocity of rat nasal GST was 114.3 times greater than

monkey GST towards alachlor. Velocity of secondary sulfide hydrolysis was equivalent in rat and

monkey liver preparations, but was 4 times greater in rat nasal tissue vs monkey nasal tissue.

Velocity of DEA hydroxylation in rat liver was 3 times greater than in monkey liver, and 7.6 times

greater in rat nasal tissue than in monkey nasal tissue. Thus, the enzymes thought to be responsible

for production of the toxic intermediate of alachlor are more active in rat nasal tissue vs monkey nasal

tissue. 

 

In MRID No. 43482301, cytosolic and microsomal fractions from rat and human liver and

nasal tissue were studied to determine the differential species capability to conjugate alachlor with

glutathione, to hydrolyze the secondary methyl sulfide (secondary sulfide), and to hyroxylate the
27

2,6-diethylaniline metabolite of alachlor. Velocity of glutathione conjugation in rat liver and nasal

tissue was 4.0 and 32.5 times greater than in human liver and nasal tissue, respectively. Velocity of

hydrolysis of the secondary sulfide was 5.8 times greater in rat nasal tissue vs human. Velocity of

DEA hydroxylation was 7.5 times greater in rat liver vs human, and 129.8 times greater in rat nasal

tissue vs human.

Whole body autoradiographic (WBA) studies conducted in rats, mice, and monkeys provided

further support for the species specificity of the mechanism of alachlor-induced nasal tumors. In

MRID No. 42852103, WBA studies in rats, mice, and monkeys following single oral doses of 7, 70,

and 700 mg/kg were conducted. A similar picture of tissue distribution was observed in all species

with the exception of blood, in which significant amounts were observed only in the rat at 5 days

post-dose, and the nasal turbinates, in which significant accumulation was observed in the rat, less

in the mouse, and none in the monkey. Comparative WBA studies on the localization of alachlor,

metolachlor, and MON 4601 were conducted in male and female rats after target doses of 7 and 700

mg/kg (MRID No. 42852104). Nasal turbinate localization appeared less for alachlor than for

metolachlor and MON 4601 at one day post-dose at the 7 and 700 mg/kg dose. The data in this

study indicated a faster clearance of alachlor from the intestinal tract vs metolachlor and MON 4601,

and also indicate that metolachlor and MON 4601 undergo biliary excretion and enterohepatic

circulation. Whole body autoradiography studies of the localization of the methylsulfide metabolite

in rats after oral administration at 0.7 and 7.0 mg/kg (MRID No. 42651304) and localization of the

diethylaniline metabolite of alachlor in rats after oral administration of 7 and 70 mg/kg (MRID No.

43507401) showed that for the methyl sulfide metabolite, localization in the nasal turbinate was

evident up to 5 days post-dose, while for the diethylaniline metabolite, nasal turbinate localization was

evident in the rat but not the mouse. Comparative distribution of alachlor using WBA after oral doses

of 7 and 70 mg/kg was examined in Sprague-Dawley, Long-Evans, and Fisher 344 rats as well as in

Syrian hamsters (MRID No. 42852105). Nasal localization was evident in all three strains, but was

most apparent in the Long-Evans rat. Nasal localization was not evident in the hamster.

Collectively, these WBA studies support the conclusion that the distribution of alachlor

derived radioactivity to the nasal turbinates, as well as that of alachlor metabolites thought to be

involved in nasal tumor formation, is greater in the rat than in the mouse or monkey. When

considered in conjunction with in vitro studies on the activities of enzymes responsible for formation

of the DEBQI intermediate, it is evident that not only does alachlor derived radioactivity localize to

the rat nasal turbinate tissue to a greater degree than in mice or monkeys, but that the activities of the

enzymes involved in the conversion of the secondary sulfide to the DEBQI intermediate are

significantly higher in the rat than in the mouse, monkey, or human. 

The mechanism of alachlor-induced nasal tumors is considered by the registrant as a

non-genotoxic mechanism. This argument is largely based upon the mutagenicity database, in which

it is argued that alachlor has no significant genotoxic activity in mammalian systems. Studies

examining the effect of alachlor administration on tissue glutathione levels following in vivo

administration of oral and intraperitoneal doses of alachlor to Long-Evans rats as well as the effect

of alachlor on glutathione levels in cultured hepatocytes have been conducted (MRID Nos. 42651318
28

and 43641603). These studies showed depletion of hepatic glutathione followed by recovery after

a single i.p. dose of 350 mg/kg or single oral doses of 126 or 350 mg/kg. Alachlor was hepatotoxic

at concentrations above 400 FM, and significant glutathione depletion was also observed at

concentrations above 300 FM alachlor. While no significant depletion of nasal glutathione levels

were observed, the DNA damaging effect of alachlor might be related to depletion of glutathione and

subsequent tissue toxicity, and not to a direct mode of action. It is noted that significant hepatoxicity

in the form of elevated serum ALT (alanine amino transferase), AST (aspartate amino transferase),

and LDH (lactate dehydrogenase) as well as centrilobular cytoplasmic eosinophilia, centrilobular

inflammation, and centrilobular hepatocellular degeneration/necrosis was observed at a dose of

alachlor (1000 mg/kg) which also caused a weak UDS response. These data are consistent with a

non-genotoxic mode of action for alachlor. 

With regard to the nasal tissue, two studies addressed the mechanism of nasal turbinate

induced tumors. In the first study (MRID No. 43641604), female Long-Evans rats were fed 14-C

alachlor in the diet at a targeted dose level of 126 mg/kg/day for a total of 13 days. On days 1, 3, 7,

and 13, 3 rats were sacrificed and the covalent binding of alachlor derived radioactivity to nasal

protein was determined. The results of this study showed a direct correlation between the total level

of alachlor binding to rat nasal proteins and length of treatment. The major adduct was identified as

the 3,5-diethylbenzo-quinone-4-imime (DEBQI)-cysteine adduct. Formation of DEBQI in the rat

nasal tissue is believed to be required for induction of nasal tumors. In the second study (MRID No.

43641602), the in vitro cytotoxicity of alachlor, DEA, secondary sulfide, and secondary amide were

assessed in preparations of rat nasal turbinate as evidenced by leakage of the enzyme acid phosphatase

into the culture medium. Concentrations of alachlor and metabolites used were either 1 or 5 mM.

Alachlor at both 1 and 5 mM was shown to increase acid phosphatase levels in the culture medium.

Neither the secondary sulfide or secondary amide caused an increase in acid phosphatase levels at 1

mM (5 mM concentration not possible due to solubility limitations). DEA was observed to increase

acid phosphatase levels at 5 mM in nasal tissue. The cytotoxicity observed with alachlor in nasal

tissue is consistent with the cell proliferation response observed in nasal tissue after administration

of alachlor, but the entity responsible for the cytotoxic response is not known with certainty. 

Gastric Tumors

In response to scientific and regulatory questions raised in Japan, an extensive research

program was undertaken to understand the mechanism by which chloroacetanilides induce stomach

tumors in rats. The majority of this work was conducted with butachlor in Sprague-Dawley rats.

Since butachlor is a close structural analog of alachlor, and the two compounds produce the same

glandular stomach tumors, extrapolation of the mechanistic information to alachlor is scientifically

justified. To further support this, some bridging data have been developed with alachlor and were

previously reported to the Agency. The purposes of these provided data are to: (a) report the results

and conclusions of the mechanistic studies conducted with butachlor; and (b) integrate these results

with those from the alachlor work to show that the same mechanisms are operative for both

herbicides.
29

In a gastric tumor initiation/promotion study (MRID No. 43729502) the results showed that

butachlor had no initiating potential of its own when used at dose levels which produced gastric

tumors in the chronic toxicity study in rats. Butachlor was found to enhance the formation of gastric

neoplasms when combined with an initiating agent. This occurs primarily in females and at the dose

which induced neoplasms in the chronic rat study. In a study of the mechanism of butachlor induced

carcinogenicity in female Sprague-Dawley rats (MRID No. 43750801) the investigators concluded

that these data delineated the mechanistic processes involved in the production of the gastric, nasal

and thyroid tumors for butachlor. It was suggested that the data provided support for the

involvement of non-genotoxic mechanisms that would be threshold sensitive to humans. They also

stated that these studies further support the view that the rat tumors induced by butachlor are not

relevant to man and that butachlor does not pose a human health risk (not formally reviewed by the

Agency). In a study on the effect of butachlor on cell proliferation in selected tissues of the mouse

(MRID No. 43729503) the investigators found no consistent increase in cell proliferation in either

the fundic or pyloric regions. There was a slight increase in the fundic neck region but not in the base

region and there was no evidence of toxicity in the mucosa. In another study on the effects of

butachlor on cell proliferation and mucosal thickness in the gastric tissue of female Rhesus monkeys

(MRID No. 43729501), according to the investigators there were no relevant changes in cell

proliferation in any area of the stomach and no changes in the mucosal thickness in any of the

monkeys up to and including 400 mg/kg. The results of this study differ from those studies in the rat,

where increases in proliferative activity and reductions in mucosal thickness were observed. The

doses used in the monkey are reported to exceed the MTD in the rat by 2 to 4 times.

The registrant conducted an initiation-promotion study with alachlor (MRID No. 43590001)

as a follow-up to a stomach tumor initiation/promotion study with butachlor. In this study, 100 male

and 100 female Long-Evans rats obtained from Charles River Breeding Laboratory, Portage, MI, 6

weeks of age and weighing 168-219 g for males and 139-176 g for females were administered by oral

gavage a single dose of 150 mg/kg of the known gastric tumor initiator N-methyl-N’-nitro-N-nitrosoguanidine (MNNG) to 4 groups of 20 animals per sex. One of these groups was not further treated.

Another group received dietary administration of 8000 ppm catechol, and two groups received either

15 or 126 mg/kg/day of alachlor in the diet for 1 year while another group (not MNNG treated)

received a single oral dose of DMSO (5 mL/kg) followed by dietary administration of alachlor at a

level of 126 mg/kg/day (there was another group of 15 animals per sex obtained near the end of the

study to serve as “control” animals for serum gastrin levels, gastric fluid amount, pH, and HCl

concentration). The investigators determined, at the end of the study, stomach pH, gastric acid

secretion over a 4 hour period in 5-6 of the control and DMSO/Alachlor treated animals. They also

obtained blood from 9-10 control and DMSO/Alachlor treated animals for serum gastrin

determinations. The stomachs of all animals were examined grossly and microscopically. 

Alachlor was found to promote the development of glandular stomach tumors in females and

to a lesser extent in males. No effect of treatment was noted in the animals treated with MNNG alone

(1 tumor). Alachlor alone produced no tumors in males and 4 tumors in females. MNNG/alachlor

treated animals produced tumors in 75% of treated females and 30% of treated males at 126

mg/kg/day. These tumors were neoplasms of the glandular stomach, mostly in the fundus region.
30

In the 15 mg/kg/day alachlor + MNNG no tumors were observed in the females. However several

tumors were found in males at both doses and in females at the 126 mg/kg/day dose following

MNNG. The investigators interpreted this as due to MNNG rather than alachlor, since they occurred

at equivalent frequency in the males at both doses, the lower of which had no promotional activity.

In a previous butachlor initiation/promotion study, the group treated with MNNG only induced

adenomas and adenocarcinomas in the pyloric region. Alachlor administration was noted to produce

atrophy of the fundic mucosa in almost every animal at 126 mg/kg/day both with and without the

initiator, MNNG. No atrophy was noted in any animal at 15 mg/kg/day alachlor for one year. The

high dose alachlor animals of both sexes had reduced amounts of fluid in the stomachs. Stomach pH

was numerically increased, and gastric hydrochloric acid secretion was decreased and serum gastrin

levels were elevated in high dose animals. 

The Agency believes that the data provide evidence that alachlor produces glandular stomach

tumors in rats through the same non-genotoxic, non-linear sensitive mechanism as butachlor and that

this mechanism may be operative in humans under certain specific pathological states. 

Alachlor has been shown to produce glandular stomach tumors in Long-Evans rats at doses

considered in excess of an adequate dose for carcinogenicity testing. Butachlor also induced these

gastric neoplasms in Sprague-Dawley rats following chronic high dose exposure. In this butachlor

bioassay, the occurrence of gastric tumors was restricted solely to the highest dose tested (150

mg/kg/day), a level of exposure which was considered greatly in excess of an adequate dose for

carcinogenicity testing. In a butachlor chronic bioassay with F-344 rats, the highest dose was

considered adequate for carcinogenicity testing, and no gastric tumors were found. This and other

information indicate that chloroacetanilides produce stomach tumors in rats via a non-linear type

mechanism. 

The Agency evaluated the data submitted by the registrant in support of the threshold (nonlinear) type mechanism for induction of gastric tumors by alachlor and concurred with the explanation

put forth by the registrant. 

Thyroid Tumors

Mechanistic data in support of the thyroid tumors consisted of two studies. In the first, dose

levels of 0 or 126 mg/kg/day were used to measure indices of thyroid function (T3, T4, and TSH

levels). While the results of this study showed no significant effect of alachlor on T3, T4, or TSH

levels, the results pertaining to TSH levels were considered invalid based on the use of human

antibodies in the TSH assay. 

In the second study (MRID No. 42957201), Long-Evans rats were dosed with alachlor for

up to 120 days at dose levels of 0 and 126 mg/kg/day. Separate groups were exposed to control diet

or alachlor in the diet for 7, 14, 28, 60, or 120 days, with a separate group exposed to alachlor for

60 days in the diet and then control diet for 60 days. The results of this study showed increased liver

weights at all time points, increased activity of uridine 5’-di-phosphoglucuronyl transferase
31

(UDPGT), and increased thyroid weights from day 14 throughout the remainder of the study. TSH

levels were statistically significantly increased from day 14 on, although the increase at day 120 was

not significant. T3 levels were increased over control at 7, 14, 60, and 120 days; T4 levels were

decreased at 7 and 28 days and increased at 14 days, returning towards normal at following time

points. The dose group which received alachlor for 60 days followed by 60 days of control diet

showed relatively unaffected T3, T4 and TSH levels. Thyroid follicular hypertrophy/hyperplasia was

also noted in the treated animals mainly in the 28 and 60 day groups, with 1 animal in the 120 day

group progressing to nodular hyperplasia.

The results of the above studies suggest that thyroid tumors (which only occur in the male

rat), result from induction of hepatic UDPGT, with a consequent decrease in circulating T3 and T4

and a subsequent increase in TSH (the compensatory response resulted in increased T3 levels). This

action is known to result in a hyperplastic response of the thyroid. The mechanism of thyroid

tumorigenesis observed with alachlor is consistent with the mechanism of thyroid tumorigenesis

observed with other chemicals causing a disruption of thyroid hormone balance. 

Human Studies

Human Biomonitoring

A biomonitoring study of a pesticide involves following a group of workers during a defined

field use of the pesticide. Urine is collected before and after exposure and analyzed for metabolites

of the pesticide. From this data one determines the quantity of pesticide absorbed during the defined

field exposure. Thus, a biomonitoring study consists of two parts (1) a qualitative and quantitative

identification of the metabolites of the pesticide, usually by following radiolabel in a mammalian

species, and (2) the field study in human subjects.

In the three submitted biomonitoring studies the internal dosage of alachlor was estimated by

analysis of the urinary excretion of alachlor metabolites which contained the DEA and HEEA

moieties.

The first biomonitoring study (MRID No. 00150089) was conducted using two formulations

of alachlor, the EC (emulsifiable concentrate) and the Mcap (microencapsulated). The study was

designed to determine the dosages of alachlor in workers, and to compare the dosages of the two

formulations. The study was conducted in Indiana during May 1984. Both the EC and Mcap were

applied by shallow incorporation to corn fields at an application rate of 4 lbs a.i./acre. Each

formulation was applied by four different individuals. Applicators 1, 3, 5, and 7 applied EC and

applicators 2, 4, 6, and 8 applied Mcap. Additionally a control subject was present at the field during

the application. 

The subjects were Monsanto employees who wore goggles and elbow length rubber gloves

during mixing/loading and leather boots, trouser, long sleeve shirts and caps throughout the entire

operation. The clothing was in agreement with the protective clothing requirements stated on the
32

labels. Each applicator emptied eight 2.5 gallon containers of EC or Mcap into 200 gallon tanks.

Water was added from nurse tanks with constant agitation. Immediately following mixing, the

worker entered a closed cab and applied the alachlor to 20 acres.

The urine from each worker was collected in a borosilicate glass bottle with teflon cap for 120

hours (5 days) after the alachlor application was completed. The samples were analyzed for

metabolites of alachlor containing the DEA and HEEA moieties using GC/MS. Urine samples with

non-detectable levels of alachlor metabolites were computed as containing 1.25 ppb (one-half the

LOD, limit of detection, of 2.5 ppb). The practice of using one-half of the LOD is a standard

analytical procedure for dealing with the analytical LODs for chemical residues.

The highest internal dosage for mixing, loading and applying (of the four replicates) for EC

formulation was estimated to be 0.0066 Fg/kg/lb ai. The internal dosage for the Mcap was estimated

to be 0.027 Fg/kg/lb ai. 

Another biomonitoring study (MRID No. 00159365) was conducted in May and July 1985

in Missouri. In this study the Mcap and WDG (a water dispersable granular formulation), were

evaluated. This study was conducted in a manner similar to that of the May 1984 bio-monitoring

study: Monsanto employees wearing clothing in accordance with the label, 4 lbs ai/acre, and 20

acres. Open loading was used, with each subject handling 80 lbs ai. Control urine samples were

collected prior to study initiation. Urine was collected for 5 days. The urine samples were also

analyzed for alachlor metabolites containing the DEA and HEEA moities, but by HPLC (high

performance liquid chromatography).

No measurable levels of the alachlor metabolites containing the HEEA moiety were detected

in any urine samples for all study subjects. Measurable levels of DEA metabolites were detected for

most of the subjects, primarily within the first 48 hours. The internal dosage of the Mcap was

estimated to be 0.0038 Fg/kg/ai. The internal dosage of the WDG was estimated to be 0.0059

Fg/kg/lb ai.

A third biomonitoring study (MRID No. 00159364) was also performed in May and July

1985. This study was also conducted in the same manner as that of the Mcap and WDG 1985 biomonitoring study. However, a closed loading system was used to transfer the EC. The internal

dosage of the EC was estimated to be 0.0034 Fg/kg/lb ai.

For all three studies the Agency has concerns due to the small number of replicates as well

as the use of protective clothing and the use of the closed cab. Only 20 acres were treated instead

of the 100 to 120 acres that could be expected to be treated and incorporated. Additionally, the

scenario is only representative of 4 lb ai/acre. The small number of replicates cannot indicate the

range of dosage that would be expected. Due to the protected nature of the applicators (clothing and

cab) it was assumed that the dosage estimate is from the lower end of the range. A literature search

of ground boom application studies indicated that exposure to the applicators ranged over three

orders of magnitude. In the alachlor PD4 two orders of magnitude was chosen by the Agency to
33

define the exposure range since mixing and loading is included in the dosage estimates with the

estimate from the Monsanto bio-monitoring studies considered to be the low end of the range.

As part of the reregistration process, the first biomonitoring study (May 1984, Indiana) was

rereviewed. The review indicated that there is probably a formulation related difference for

application of the EC versus the Mcap. For the 4 lb ai/acre scenario, the internal estimated dosages

were: EC = 0.0032 Fg/kg/lb ai, and Mcap = 0.0126 Fg/kg/lb ai. The same internal exposure

estimates would be appropriate for mixer/loaders, mixer/loader/applicators, or applicators.

Epidemiology Study of Ocular Health Among Alachlor Manufacturing Workers

During a chronic feeding study (MRID No. 00139021) with alachlor, Long-Evans rats were

noted to develop severe ocular lesions at the highest test doses. Therefore, another study in LongEvans rats was conducted to characterize the progression of the previously observed eye lesions

(MRID No. 00141060). It was observed that females were more sensitive than males, and that once

the uveal degereration syndrome was observed, it was irreversible. 

To determine if human workers might be at risk of developing similar lesions, it was decided

to conduct an ophthalmologic study which would focus on a human eye lesion that could be

considered equivalent to the initiating eye lesion found in Long-Evans rats. Differences between

Long-Evans rat and human eyes were considered to be minor; thus, an equivalence for the purpose

of evaluating a potential effect of alachlor exposure among workers could be assumed. The uveal

tract consists of the iris, ciliary body, and choroid. Long-Evans rats, like humans, have pigmented

eyes and each uveal component has melanin-containing cells. The human equivalent of the initiating

lesions, uveal pigment disruption and dispersion, is the clinically described Pigment Dispersion

Syndrome (PDS). PDS consists of the loss of pigment from the mid-posterior iris with deposition

of the pigment on the cornea, trabecular meshwork, lens, and iris.

The study site was the Muscatine, Iowa plant, which began operation in 1961. At Muscatine,

herbicide production began in 1964, with the production of alachlor beginning in 1969. To determine

whether there were ocular effects among exposed workers, a group of 135 highly exposed alachlor

production workers were examined for the presence of PDS. There was a control group of 84

unexposed co-workers and relatives. All participants were examined by the same ophthalmologist

at the University of Iowa. The ophthalmologist was unaware of the exposure status of the individual

participants.

Components of the eye exam included slit-lamp biomicroscopy of the anterior chamber and

a dilated exam of the lens and fundus with scleral depression as well as the routine functional exam.

Intraocular pressure was measured prior to dilation. Only one study participant had eye defects

meeting the study criteria of PDS. This person was in the control group. For eye abnormalities other

than PDS, prevalence rates were similar for exposed and unexposed study participants.

Thus, no evidence of increased risk of ocular disease was found when workers were compared
34

to controls. Only one subject, who was from the control group, had the same defect as reported in

the study of Long-Evans rats. (MRID No. 43267501)

Epidemiologic Study of Workers

Monsanto performed an epidemiologic study of workers at an alachlor manufacturing plant

in Muscatine, Iowa. The product has been manufactured in this plant since 1969. (MRID No.

43878501). The population studied included 1199 workers employed for 1 year or more between

1961 and December 1993. Both mortality and cancer incidence were assessed in this cohort.

Mortality follow-up was by company records, social security number, national death index, credit

agency, and state motor vehicle records. Follow-up for vital status was very successful, covering

over 99% of the cohort. Death certificates were obtained for all 17 decedents.

Assessment of cancer incidence was conducted using the statewide cancer registry in Iowa

which was initiated in 1969. Linking with the registry was by social security number, full name, and

birth date. Inexact matches were verified by consulting with employee records and the State Health

Registry. Workers who left Iowa (< 1/3 the cohort) did not have cancer incidence assessed but were

assumed to be similar to those who remained in state.

Quantitative data were insufficient to estimate actual exposure at the plant. Qualitative

estimates (high, medium, and low) were made by industrial hygienists based primarily on work history

and the potential for dermal exposure. Alachlor's low vapor pressure and airborne measurements

taken at the plant (averaging less than 10 ppb) suggest this route of exposure is not significant. The

potential for contaminated water occurred between 1968 and 1975. In 1975 low levels of alachlor

were detected in the plant's drinking water. However, when the alachlor first appeared in the drinking

water is not known. Exposure characterization took into account the contaminated drinking water.

Analysis both included and excluded this possibility due to the uncertainty associated with it.

Twenty-six non-whites were excluded from the analysis due to inadequate sample size for statistical

analysis. However, it was noted that no cancers occurred in this group where 0.1 cases would have

been expected. 

No deaths or incidence of cancer were reported for the stomach, thyroid, or nasal cavities,

as reported in laboratory rats. The study did not find any evidence of statistically increased incidence

or mortality from cancer either overall or by individual cancer site with one exception. The one

statistically significant finding was based on two cases of chronic myeloid leukemia where only 0.1

cases would have been expected. The 95 percent confidence interval for the standardized incidence

ratio was quite wide, 1.9 to 58.1. Given that this ratio is based on only two cases (one of whom had

worked at the plant less than 5 years) and the number of statistical tests performed, this result should

probably be considered a chance finding without other supporting evidence. 

By completion of this study only 24 cancers and 8 cancer deaths had been reported in the

entire cohort. The overall cancer mortality ratio (number of observed/expected cases) was 0.9 with

a 95% confidence interval of 0.4 to 1.7. The overall cancer incidence ratio was 1.4 based on 24
35

observed and 17.1 expected cases (95% confidence interval 0.9 to 2.1). For those workers

categorized as having high exposure to alachlor (68% of the cohort), the cancer incidence ratio was

1.2 (95% confidence interval 0.7 to 2.0). The Agency concludes that while no appreciable hazard

has been identified to date, one cannot rule out adverse effects in this cohort until these individuals

have been followed-up over the course of a lifetime.

i. ESA Metabolite of Alachlor

The ethane sulfonic acid (ESA) metabolite of alachlor is variously referred to as MON 5775,

2',6'-diethyl-N-methoxymethyl-2-sulfoacetanilide, sodium salt or 2-[2,6-diethylphenyl

(methoxymethyl) amino]-2-oxoethane sulfonic acid, sodium salt. The formation of alachlor ESA

involves the displacement of a chlorine atom by a sulfonic acid moiety. The metabolic route leading

to alachlor ESA is postulated to involve initial glutathione displacement of the chlorine atom,

followed by successive degradation of the sulfur conjugated moiety through organic acid and

methylsulfone intermediates, to ultimately form the sulfonic acid group as a terminal oxidative

degradate. Alachlor ESA has always been isolated from natural matrices and synthetic preparations

as a salt. The sodium salt has always been utilized for toxicology studies.

Alachlor ESA was originally identified as a metabolite of alachlor in soil (MRID No.

00134327). The alachlor ESA metabolite was determined to be 15 - 25% of the total applied

radioactivity, making it the first or second most prevalent degradate in soil. Alachlor ESA has also

been quantified in field soil dissipation studies following alachlor applications (MRID Nos. 42528002,

43774701). Low concentrations were detected, but alachlor ESA was not found to persist or leach

below 18 inches.

Alachlor ESA has also been identified as a minor alachlor degradate in a laboratory aqueous

sediment metabolism study (MRID No. 43774702). It has also been detected in water samples from

Indiana (MRID No. 42479901) and Wisconsin (no MRID, submitted under FIFRA 6(a)(2)). In the

Indiana well water samples, alachlor ESA concentrations ranged from <1.0 - 23.0 Fg/L, and in

Wisconsin they ranged from <1.0 - 26.7 Fg/L. 

Acute Toxicity

In an acute oral toxicity study in rats, the acute oral LD50 of alachlor ESA is greater than 6000

mg/kg. This is toxicity category IV (MRID No. 42701501). 

Subchronic Toxicity

In a special 91-day drinking water study, male and female Fischer CDF® F-344 Crl BR

VAF/Plus® rats from Charles River Laboratories, Inc. (Raleigh, NC) received either 0, 200, 2000,

or 10000 ppm (male: 0 (control), 16, 157, or 896 mg/kg/day; female: 0 (control), 23, 207, or 1108

mg/kg/day) alachlor ESA. Systemic toxicity was observed in high dose male and female rats, with

increased incidences of decreased activity with rapid/shallow breathing, few feces and feces small in
36

size, dehydration, urine staining, emaciation, hunched posture, rough coat, unkempt appearance, and

dark material/stain on pads of forelimb, around eyes, mouth and nose, clear and red ocular discharge,

and hair loss around eyes. Slight decreased body weight gains (10%) were also noted in high dose

male rats (decreased body weight gains were noted in all treated females; however, no dose response

was noted). Several statistically significant hematological effects (decreased hemoglobin, hematocrit,

red cells, increased MCH and MCHC) and clinical chemistry alterations (decreased AST, ALT, urea

nitrogen, albumin, glucose, increased bilirubin and phosphorous) were observed at the mid and high

dose in males and/or females, but were minor, mostly not dose related and were not considered

biologically relevant, especially in the absence of any organ or tissue pathology at this dose. Eye

lesions noted in this study were determined not to be related to treatment or to those lesions seen with

the parent compound, alachlor. The clinical observations reported related to the eye are due to ocular

abnormalities specific to the F-344 rat. The systemic toxicity NOEL was 2000 ppm (157 mg/kg/day

in males and 207 mg/kg/day in females). The systemic toxicity LOEL was 10,000 ppm (896

mg/kg/day in males and 1108 mg/kg/day in females) based on increased incidence of clinical signs of

toxicity in males and females, and decreased body weight gains in males (MRID No. 42863701).

Developmental Toxicity

In a prenatal developmental toxicity (teratology) study, female Sprague-Dawley Crl:CD®BR

rats from Charles River Breeding Laboratories, Inc., (Portage, Michigan) received 0 (control), 150,

400, or 1000 (limit dose) mg/kg/day alachlor ESA (90.0% a.i.; Lot No.: NPD-9203-3974-T) in corn

oil by oral gavage from days 6 through 15 of gestation, inclusive. Actual doses were 0, 135, 360, or

900 mg/kg/day based on 90.0% a.i. No maternal toxicity was noted in any measured parameter at

the dose levels tested. The maternal toxicity NOEL is equal to or greater than 900 mg/kg/day and

the maternal toxicity LOEL is greater than 900 mg/kg/day. No developmental toxicity was noted in

any measured parameter at the dose levels tested. Therefore, the developmental toxicity NOEL is

equal to or greater than 900 mg/kg/day, and the developmental toxicity LOEL is greater than 900

mg/kg/day (MRID No. 43908101).

Mutagenicity

In an Ames Salmonella mutagenicity assay, alachlor's ethanesulfonic acid, or ESA metabolite,

did not cause increases in the reversion of four S. typhimurium strains (TA98, TA100, TA1535, and

TA1537) in either the presence or absence of S9 activation at dose levels of 0.01 to 10.00 mg/plate

under the conditions of two independent assays (MRID No. 00151398).

In a mouse micronucleus assay, groups of five male CD-1 mice received single oral gavage

administrations of 500, 1000 or 2000 mg/kg alachlor ESA (90.7%). The test material was delivered

to the animals in deionized water. Animals were sacrificed at 24 and 48 hours postadministration;

bone marrow cells were harvested and 2000 erythrocytes per male were examined for the incidence

of micronucleated polychromatic erythrocytes (MPEs). No overt toxicity for the treated animals or

cytotoxicity for the target organ was observed up to the currently recommended limit dose (2000

mg/kg). The positive control induced the expected high yield of MPEs in the treated males. There
37

was, however, no evidence that the test material induced a clastogenic or aneugenic effect at any dose

or sacrifice time (MRID No. 43889403). 

Metabolism

In a special metabolism study, two groups of male and female Long-Evans rats

(two/sex/group) were administered alachlor ESA at a dose of 70 mg/kg by gavage. Group 1 rats were

sacrificed 24 hours after treatment and Group 2 rats at 5 days after treatment. Disposition of alachlor

ethane sulfonate was determined by collection of excreta and by whole-body autoradiography.

Metabolism was assessed by HPLC analysis of processed urine and feces samples. The major route

of excretion for alachlor ESA at 70 mg/kg was the feces, with 71-82% of the administered dose

excreted by this route. Excretion was rapid with the majority of radioactivity excreted by 24 hours

post-dose. HPLC analysis of urine and feces showed alachlor ESA to be the major component in

both urine and feces, with three other components isolated but not identified, each comprising less

than 2% of the dose. Autoradiographic data on alachlor ESA derived radioactivity at 14 hours

postdose showed the major areas of localization were stomach contents, cecum, intestinal contents

and urinary bladder. The data indicate that alachlor's ESA metabolite is poorly absorbed, rapidly

excreted, and undergoes minor metabolism. (MRID No. 43889404). 

Special Studies

In a special study, the proliferating cell nuclear antigen (PCNA) technique was utilized to

determine the effect of treatment with 2000 ppm alachlor ESA (157 mg/kg/day for 91 days) on cell

proliferation in the olfactory region at the second palatial ridge (Level III), where alachlor-induced

tumors are found. Mean nasal cell proliferation values (number of labeled cells per mm of mucosal

length) showed no statistically significant increases in cell proliferation in either the olfactory septum

or turbinates of male Fischer 344 rats administered alachlor ESA in drinking water for 91 days. 

(MRID No. 43889401). 

In a special study, glandular stomach tissue from female Fischer 344 rats treated with alachlor

ESA in drinking water at a dose of 10,000 ppm for 91 days was evaluated using PCNA for evidence

of a proliferative response or changes in mucosal thickness. A significant increase in the percentage

of labeled cells in the fundic neck region was observed in treated rats, but there were no significant

changes in labelling of the fundic base nor in mucosal thickness (MRID No. 43889402). 

Conclusions

Table 6: Comparison of Alachlor and Alachlor ESA 

Test Alachlor Alachlor ESA

Acute oral LD50 930 mg/kg

Toxicity category III

> 6000 mg/kg

Toxicity category IV
Table 6: Comparison of Alachlor and Alachlor ESA 

Test Alachlor Alachlor ESA

38

Subchronic

Toxicity (1)

90 day invalidated feeding

study

91-day drinking water study

males

NOEL = 157 mg/kg/day

LOEL = 896 mg/kg/day

females

NOEL = 207 mg/kg/day 

LOEL = 1108 mg/kg/day

Developmental

Toxicity

maternal

NOEL = 150 mg/kg/day

LOEL = 400 mg/kg/day

developmental

NOEL = 150 mg/kg/day

LOEL = 400 mg/kg/day

maternal

NOEL => 900 mg/kg/day

LOEL > 900 mg/kg/day

developmental

NOEL => 900 mg/kg/day

LOEL > 900 mg/kg/day

Mutagenicity weakly mutagenic - 

tested positive in 2 UDS

studies. Other alachlor

metabolites also found to be

weakly mutagenic

no mutagenic activity in two studies

Metabolism (2) Absorption was essentially

complete with alachlor

being present in the blood at

24 hours and 5 days post

dose. Alachlor excreted

approximately equally

between urine and feces. 

Alachlor ESA is the major

component in both urine and feces. 

Alachlor ESA is poorly absorbed,

rapidly excreted (71-82% in the feces

within 24 hours), and undergoes

minor metabolism.

(1) The subchronic data available for comparison of alachlor with the ESA metabolite of

alachlor are not by the same route of administration (in the diet for alachlor per se and in the drinking

water for the ESA metabolite of alachlor). Also, the study with alachlor per se is an IBT study which

was not validated nor repeated; therefore the data may be suspect. It is important to note that the

subchronic and chronic toxicity studies with alachlor were conducted with different strains of rats

(“Charles River Albino rats” vs Long-Evans rats) than the 91 day drinking water study (Fisher 344

rats); however, the available metabolism data do not show any major differences in the handling of

the compounds in the Long-Evans versus the Fisher rats.

(2) The available in vivo metabolism data indicate that in comparison to alachlor, the alachlor

ESA metabolite is poorly absorbed and metabolized to only a minor degree. The products of alachlor

ESA metabolism were not identified. The available autoradiography data indicate that in comparison
39

to alachlor, its ESA metabolite does not show any significant localization to the nasal cavity, thyroid

and glandular stomach (gastric mucosa). The available cell proliferation data indicate that in

comparison to alachlor, alachlor ESA does not induce cell proliferation.

Overall, the data provided indicate that alachlor's ESA metabolite has less toxic potential than

the parent alachlor.

Metabolism Committee Meeting for Alachlor ESA Metabolite

A Metabolism Committee meeting held 1/18/95 discussed the available toxicity data for the

alachlor ethane sulfonic acid (ESA) metabolite. 

The Metabolism Committee concluded the following:

C Since alachlor ESA is sulfonated, and highly polar, there is likely to be little absorption via

the oral or dermal routes, and even if absorbed, it is expected to be readily excreted.

C Information has been provided by the Registrant which indicates toxicity of the parent is

based in part on formation of the quinone imine. 

C Formation of the potentially carcinogenic quinone-imine from alachlor ESA is unlikely if the

metabolite occurs solely in the sulfonated form in the body, or if minimal cleavage to the

unsulfonated form occurs.

C Because of the reasons cited above, alachlor ESA is unlikely to be carcinogenic in a 2-year

bioassay.

C Alachlor ESA should, however, continue to be included in non-cancer dietary exposure

estimates (for comparison to the RfD).

C Alachlor ESA was non-mutagenic in two studies.

2. Dose Response Assessment

a. Reference Dose

A Reference Dose (RfD) represents the quantity of a substance which if absorbed on a daily

basis over a lifetime, is not expected to pose significant risk of adverse health effects.

The RfD for alachlor was first assessed on February 21, 1986. This RfD was subsequently verified

by the Agency RfD Work Group on March 11, 1986, and again on March 27, 1991. 

At that time the RfD was based on a NOEL of 1 mg/kg/day in a one year chronic dog study

(MRID No. 00148923). The LOEL was 3 mg/kg/day based on hemosiderosis and hemolytic anemia.

An uncertainty factor (UF) of 100 was used to account for interspecies extrapolation and intraspecies

variability. The RfD was calculated to be 0.01 mg/kg/day.

The RfD Committee met on 8/19/93 (actual memo was signed 1/31/94) to discuss and

reevaluate the RfD for alachlor. At this meeting, it was recommended that the RfD of 0.01
40

mg/kg/day remain unchanged.

b. Dermal Absorption

The requirement for a dermal absorption study in the rat was waived, since data from three

Rhesus monkey studies (MRID Nos. 00149403, 00149404, 00149405) were combined to determine

the dermal absorption factor.

Three pharmacokinetic studies on Rhesus monkeys were performed: an intravenous route

of administration study, dermal application of alachlor emulsifiable concentrate (EC), and a dermal

application of alachlor micro-encapsulate formulation (Mcap). In all three studies, the levels of

radioactivity were monitored in the blood for 7 days, and urine and feces for 9 to 14 days.

The purpose of the intravenous study was to determine the pharmacokinetics of alachlor

distribution and elimination. Two monkeys/sex/dose were given single doses of 0.24 or 2.4

mg/kg/day. Alachlor was rapidly distributed in the blood (whole, plasma, and red blood cells) within

the first 15 minutes, and rapidly eliminated in urine primarily within the first 24 hours. Approximately

93.3 percent of the low dose and 99.6 percent of the high dose were eliminated in excreta during the

10-day study period. The majority of this elimination was via the urine (82.1% low dose, and 91.4%,

high dose).

In both the EC and the Mcap dermal studies, the formulations were tested undiluted and

diluted (1:29 for EC and 1:17 for Mcap) with water, 2 monkeys/sex/formulation or dilution/EC or

Mcap. The dosages (EC: 32 Fg/cm2 and 300 Fg/cm2; and Mcap 10.8 Fg/cm2 and 217 Fg/cm2) were

applied to a 40 cm2 skin area and were left on the skin for 12 hours before removal.

For the EC the rate of alachlor absorption was slow and reached a peak in the blood after 24

hours. The total dermal absorption in the low dose animals (32 Fg/cm2), estimated from excretion

of radiolabel and retention of label in tissues, was 6-7% in males and 12-13% in females, uncorrected.

However, calculation of the actual amount of test material absorbed through the skin was complicated

by the fact that recovery of radiolabelled test material in this test group was poor, ranging from 21

to 77% of the nominal amount applied. Data were submitted demonstrating that up to 40% of the

applied dose could apparently evaporate from skin (under conditions simulated in vitro) and that

application error could result in application of up to 20% less than the nominal value. In the face of

these uncertainties, values for excretion and absorption were calculated based upon the amount of

radiolabel that was recovered. Using these correction factors, absorption was 10-24 % (low dose)

in males and 16-20% (low dose) in females.

For the EC, recovery of radiolabel was better in the high dose animals (300 Fg/cm2), and

application of a correction factor had little effect. Absorption was 4-9% in males and 10-11% in

females.

It is also possible to estimate a percent dermal absorption by using a ratio of the corrected
41

percent radiolabel excreted in urine after dermal application to the average percent radiolabel excreted

in urine after intravenous administration, which is 87%. Using this ratio, the dermal absorption

estimates for the low dose EC group were 9.2-24.8% for males and 16-21.8% for females. For the

high dose EC group, the dermal absorption estimates were 4.7-8.9% for the males and 10.7-11.4%

for the females. Thus, similar estimates of dermal absorption were obtained by either method of

calculation. 

For the Mcap, the total dermal absorption for the low dose (10.8 Fg/cm2) ranged from 3-23%

in males and 6-7% in females. For the high dose (217 Fg/cm2) the total dermal absorption ranged

from 2-4% in males and 3-4% in females. Percent dermal absorptions were also estimated using the

ratio specified in the discussion of the EC group. Using this ratio, the dermal absorption estimates

for the low dose Mcap group were 3.2-23.4% for males and 6.7-7.1% for females. For the high dose

Mcap group, the dermal absorption estimates were 2-3.8% in males, and 2.2-3.9% in females. Again,

similar estimates of dermal absorption were obtained by either method of calculation.

c. Cancer Classification

The carcinogenicity of alachlor was first evaluated by the Agency’s Cancer Peer Review

Committee on March 25, 1986. The information available at the time included two chronic rat

studies, a special 2-year rat study for ocular lesions, and an 18 month mouse study, as well as

historical control data on the mouse, several in vitro and in vivo mutagenic assays, and metabolism

data.

The Committee concluded that the data available for alachlor was sufficient for a classification

of B2, probable human carcinogen.

Alachlor met all but one of the criteria specified for the B2 classification, any of which

alone can be sufficient for such a classification. That is, alachlor produced an

increased incidence in malignant, or combined malignant and benign, nasal turbinate

tumors and (other tumor types) in Long-Evans rats in three different experiments at

more than one dose level via dietary administration. Alachlor also produced a

statistically significant increase in lung tumors in female CD1 mice at 2 dose levels.

In a special experiment with Long-Evans rats, nasal turbinate tumors were observed

at the end of the study (2 years), in rats that received alachlor for 5 - 6 months. The

tumor incidence was as high as 50% and tumor site was unusual; i.e., not an increase

of a normal high background tumor type. Additionally, a metabolite of alachlor was

mutagenic in the Ames test at 6 dose levels.

On November 19, 1986, the Scientific Advisory Panel (SAP) upheld the B2 classification

concluding that alachlor was a B2 carcinogen since it produced "an unusual type of neoplasm (nasal

turbinate tumors) in the rat, coupled with the finding that two metabolites of alachlor are mutagenic."

The Committee reconsidered the classification on April 15, 1987, in light of the conclusions
42

of the SAP and the registrant's rebuttal that alachlor should be classified as a C, possible human

carcinogen. Upon reconsideration of the available data and review of the registrant's arguments and

the SAP's decision, the Committee determined that alachlor's classification as a B2, probable human

carcinogen, was appropriate; thus, corroborating the March 25, 1986, decision.

A low dose extrapolation model was applied to the animal data to calculate the cancer

potency factor. The Q1

*was calculated to be 0.08 (mg/kg/day)-1

. This information was verified and

then entered into the Agency's Integrated Risk Information System (IRIS). 

As part of the Agency's peer review process, alachlor was reconsidered by the Agency’s

Carcinogenicity Peer Review Committee on September 27, and October 3, 1995, and January 3,

1996. The registrant, Monsanto, voluntarily provided new data to the Agency consisting of a new

mouse carcinogenicity study, additional mutagenicity studies, mechanistic data, special metabolism,

pharmacokinetic, and cell proliferation studies in support of a request for re-classification of the

carcinogenic potential of alachlor. These new data were reviewed by the Agency with respect to the

proposed mechanism(s) for induction of nasal, gastric, and thyroid tumors in the rat. The rat tumors

were considered to be the most relevant to alachlor risk assessment. The type of lung tumor in the

mouse is a common tumor. Since, in one of the mouse studies, the lung tumors were higher in the

males, and in the other mouse study the lung tumors were higher in females, it is possible that this is

a random event. 

Upon evaluation of all of the submitted data regarding the carcinogenicity potential of alachlor

and consideration of the full weight-of-the-evidence, the Committee could not reach a consensus as

to the classification of alachlor as a carcinogen. Therefore the Committee recommended to defer the

carcinogenicity classification of alachlor and reconsider the classification at a later date, using the new

Cancer Assessment Guidelines when such guidelines are in effect. In addition, the Committee

recommended not to utilize the linear low dose approach, but to utilize the Margin of Exposure

(MOE) methodology for the estimation of human risk. The Committee concluded that the data in

support of the mechanism for the nasal turbinates is indicative of a rat specific response. Although

the rat and human were recognized to possess the same enzyme(s) involved in production of the

putative toxic species from alachlor, it was also recognized that the activity of these enzymes was

substantially greater in the rat compared to the human. Thus, the model of rat nasal tumorigenesis

may not be relevant for human cancer assessment. Thyroid tumors have been proposed to be the

result of induction of hepatic glucuronyl transferase with subsequent decrease in circulating T3 and

T4, a subsequent increase in TSH, and eventual hyperplastic response of the thyroid. The mechanistic

data for thyroid tumor formation meet the criteria established by the Agency and the use of the MOE

approach for human cancer assessment is consistent with Agency policy. The Committee stated that

the stomach tumor formation was a direct contact effect, non-genotoxic mechanism which parallels

human pathological conditions. These tumors result from an indirect response to change in pH. The

use of the MOE approach for human cancer assessment was consistent with Agency policy.

On October 30, 1996, the SAP met to consider the weight-of-evidence for alachlor. The SAP

was asked to comment on mode of action data, provided by the registrant, for the tumor types in the
43

rat associated with administration of alachlor. The Committee met on February 5, 1997, to discuss

and evaluate the weight-of-the-evidence on alachlor with particular reference to its carcinogenic

potential and to consider the comments from the SAP. The SAP and the Committee conclusions on

the tumors induced by alachlor in the rat are summarized as follows:

Thyroid tumors: Both the SAP and the Committee agreed that the Agency requirements for

demonstrating a hormonal mode of action were met by the registrant and that the tumors

were observed only at an excessive dose.

Stomach: Evidence was presented that the carcinomas resulting from alachlor were examined

to prove that they were carcinoids, not adenocarcinomas or gastric sarcomas, and that these

carcinoids are probably related to the proposed gastrin-induced effect. Based on additional

information, the evidence alluded to was based on the butachlor study and that the tumors in

the alachlor study are considered to be carcinoids. According to the investigators: The

alachlor-induced stomach tumors were evaluated microscopically and histochemically by the

same scientists involved in the pathological/mechanistic investigations with butachlor (MRID

No. 44032101). They concluded that the tumors were gastric carcinoid, stating that the

alachlor-associated gastric tumors are poorly differentiated gastric carcinoids, histologically

and histochemically resembling the gastric tumors reported with butachlor exposure. Results

of these studies indicate that the pathogenesis and progression of the gastric tumors, and the

response of the fundic mucosa, are identical with both alachlor and butachlor. Although the

tumor increases were significant only at the highest dose (excessive), it was noted that there

was also 1 tumor (vs 0 in controls) at the mid-dose (which was considered to be adequate,

not excessive) and this is a rare tumor type.

Nasal tumors: The SAP considered these possibly relevant to humans but only at exposures

in excess of anticipated human exposures for pesticide use. The Committee considered these

tumors relevant to humans (with a quantitative difference). There also was 1 tumor at the

mid-dose (not excessive) and this too is a rare tumor type.

In accordance with the EPA proposed Guidelines for Carcinogen Risk Assessment (April 23,

1996), alachlor was characterized as "likely" to be a human carcinogen at high doses, but "not likely"

at low doses, by all routes of exposure. This conclusion was based on increased incidences of

malignant and combined benign/malignant multiple tumor types in both sexes of the Long Evans rat,

which occurred mainly at higher doses. Based on a consideration of modes of action for these

tumors, the Committee agreed that a non-linear margin of exposure (MOE) approach should be used

for the purpose of risk assessment. The consensus of the Committee was that MOEs for both the

malignant mixed gastric tumors and the nasal adenomas be presented for a risk management decision.

The Committee recognizes that while the response occurs only at higher doses and

quantitative differences exist in sensitivity between rats and humans, a similar mechanism for nasal

tumor production is present in humans, and therefore its relevance to humans cannot be dismissed.

The SAP agrees with this position. The rarity of the nasal tumor type and analysis of the structure
44

activity relationships also adds to the Committee’s concern. The presence of stomach tumors, which

are also considered a rare tumor type, and the lack of a consistent histopathologic response, leads to

the conclusion that some hazard potential may exist in humans after intense exposures. Clarification

of the similarity or dissimilarity of the relevance of the rat stomach tumors could shed light on this

uncertainty. The Committee agrees that the rat stomach tumors are relevant to humans at this time.

The Committee agrees with the SAP in that thyroid tumor induction may be relevant to humans, but

that the tumors in rats were seen at an excessive dose.

Since these are considered rare tumor types, for purposes of risk assessment, the MOE for

the nasal tumors should be determined with 0.5 mg/kg/day as the “point of departure” as no tumor

response was seen at this dose level. (Tumors were present at the next highest tested dose level,

females at 2.5 mg/kg/day, in the 1983 rat study for nasal tumors). The MOE for the stomach tumors

should be determined with 14 mg/kg/day as the “point of departure” as no tumor response was seen

at this dose level. (Tumors were present at the next highest tested dose level, females at 42

mg/kg/day, in the 1981 rat study for stomach tumors). While not statistically significant at these next

higher dose levels, the Committee considered tumor presence biologically significant due to their

rarity in rats. Thyroid tumors were observed only at an excessive dose; therefore, no “point of

departure” was determined.

d. Other Toxicological Endpoints

The toxicological effects of a pesticide can vary with different exposure durations. The

Agency considers the entire toxicity data base, and based on the effects seen for different durations

and routes of exposure, determines which risk assessments are necessary to assure that the public is

adequately protected from any pesticide exposure scenario. Both short and long durations of

exposure are always considered. Typically, risk assessments include "acute", "short-term",

"intermediate term", and "chronic" risks. These assessments are defined as follows:

Acute risk results from a one day or single event consumption of food and water, and reflects

toxicity which could be expressed following oral exposure to the pesticide residues. High-end

exposure to food and water residues are assumed.

Short-term risk results from exposure to the pesticide for a period of 1-7 days, and therefore

overlaps with the acute risk assessment. Historically, this risk assessment was intended to

address primarily dermal and inhalation exposure which could result, for example, from

occupational pesticide applications. Since enaction of FQPA, this assessment has been

expanded. The assessment will be performed when there are primary dermal and inhalation

exposures that result from residential or occupational exposures lasting from 1-7 days.

However, the analysis for residential exposures will now address both dietary and non-dietary

sources of exposure, and will typically consider exposure from food, water, and residential

uses when reliable data are available. In a short term assessment, risks from average food

and water exposure, and high-end residential exposure, are aggregated. High-end exposures

from all three sources are not typically added because of the very low probability of this
45

occurring in most cases, and because the other assumptions built into the assessment assure

adequate protection of public health. 

Intermediate-term risk results from exposure for 7 days to several months. This assessment

is handled in a manner similar to the short-term risk assessment. 

Chronic risk assessment describes risk which could result from several months to a lifetime

of exposure. For this assessment, risks are aggregated considering average exposure from

all sources for representative population subgroups including infants and children. 

An Agency Committee of toxicologists and scientists met three times to select the appropriate

endpoints for use in the alachlor risk assessment. The results of the latest meeting of that Committee

on May 14, 1996, are presented below.

Acute Dietary Assessment: 

As part of the dose-response assessment, the Agency’s toxicologists review the available

database to determine the endpoints of concern. For alachlor, there is no concern for an acute dietary

assessment since the available data do not indicate any evidence of significant toxicity from a one day

or single event exposure by the oral route. Therefore, this assessment for a one day high-end dietary

exposure is not required. 

Short-Term (1 to 7 days) Occupational Exposure Assessment: 

This assessment is required. The NOEL to be used for calculating the MOE (Margin of

Exposure) is 150 mg/kg/day from a rat developmental toxicity study (MRID No. 00043645). (The

LOEL was 400 mg/kg/day based on maternal hair loss, soft stools, anogenital staining, increased

mortality, increased post-implantation loss and a reduced number of live fetuses.) The rat

developmental toxicity study was chosen instead of the rabbit development toxicity study since the

effects in the rat developmental toxicity study were more indicative of toxicity (clinical signs and body

weights) versus those in the rabbit developmental toxicity study (body weights). Since the selected

NOEL is from a gavage study, the dermal exposure will need to be adjusted by the dermal absorption

factor to convert to oral-equivalents. Since the selected NOEL is from a developmental study, the

appropriate population subgroup is females 13+ years old. 

For all occupational scenarios, the Agency has no concerns for an MOE in excess of 100 for

non-cancer effects when the NOEL used in calculating the MOE is from an animal study.

Intermediate-Term (1 week to several months) Occupational Exposure Assessment: 

This assessment is required. The NOEL to be used for calculating the MOE is 50 mg/kg/day

from a 21-day dermal toxicity study (MRID No. 00147328). (The LOEL was 300 mg/kg/day based

on hematological and clinical chemistry changes.) Since the selected NOEL is from a dermal study,
46

the dermal exposure will not need to be adjusted by the dermal absorption factor. The selected

NOEL is from a dermal study; therefore, it could be considered inappropriate to use the total dose

(combined dermal and inhalation exposure) in the MOE calculation. However, in the case of alachlor,

the inhalation component is insignificant when compared to the dermal, so the combined total is

essentially a dermal exposure.

For all occupational scenarios, the Agency has no concerns for an MOE in excess of 100 for

non-cancer effects when the NOEL used in calculating the MOE is from an animal study.

Long-Term (several months to lifetime) Occupational Exposure Assessment: 

As part of the hazard assessment process an endpoint of concern was determined for the

chronic occupational assessment. However, during the exposure assessment process, the exposures

which would result from the use of alachlor were determined to be of an intermittent nature. The

frequency and duration of these exposures do not exhibit a chronic exposure pattern. The exposures

do not occur often enough to be considered a chronic exposure, i.e. a continuous exposure that

occurs for at least several months. Therefore, performing a long-term occupational assessment is not

appropriate.

If a chronic scenario can be identified, then this assessment is required. The NOEL to be used

for calculating the MOE is 1 mg/kg/day from a 1-year dog study (MRID No. 00148923). ( The

LOEL is 3 mg/kg/day based upon signs of hemosiderosis and hemolytic anemia.) Since the selected

NOEL is from an oral (capsules) study, the exposure will need to be adjusted by the dermal exposure

factor. 

For all occupational scenarios, the Agency has no concerns for an MOE in excess of 100 for

non-cancer effects when the NOEL used in calculating the MOE is from an animal study.

Residential 

Alachlor is a restricted use pesticide; therefore, alachlor can be used only by certified

applicators and cannot be purchased or used by the general public. The Agency has not identified any

alachlor products that are intended for home use, or uses in/around schools, parks, or other public

areas. Therefore, residential assessments are not appropriate.

Inhalation

A separate risk assessment for inhalation exposure will not be performed. The inhalation

exposure will be added to the dermal exposure, thus implicitly assuming 100% inhalation exposure.

Percent Dermal Absorption:

A dermal absorption factor of 24% as determined from the three rhesus monkey studies
47

(MRID Nos. 00149404, 00149403) will be used to adjust dermal exposures when compared to a

NOEL from an oral study.

Chronic Dietary: 

The RfD is the traditionally selected endpoint for chronic dietary risk. As previously

discussed, the RfD for alachlor was determined to be 0.01 mg/kg/day. The aggregate dietary

assessment will consider both food and water. As previously stated, there is no chronic residential

assessment to aggregate with the chronic dietary assessment.

Carcinogenic Dietary MOE Approach:

A carcinogenic assessment is required for the dietary and/or drinking water scenario. It is

likely that individuals will consume alachlor residues throughout their lifetime in the food and water

consumed. 

Given that these are rare tumor types, the MOE for the nasal tumor should be determined

using 0.5 mg/kg/day as the dose “point of departure”. No tumor response was seen at this dose level.

 Nasal tumors were present at the next highest dose level (2.5 mg/kg/day) in the 1983 rat study for

nasal tumors. The MOE for the stomach tumors should be determined using 14 mg/kg/day as the

dose “point of departure” as no tumor response was seen at this dose level. Stomach tumors were

present at the next highest dose level (42 mg/kg/day) in the 1981 rat study for stomach tumors.

Thyroid tumors were observed only at an excessive dose; therefore, no “point of departure” was

determined.

Carcinogenic Dietary Q1

* Approach:

A carcinogenic assessment is required for the dietary and/or drinking water scenario. It is

likely that individuals will consume alachlor residues throughout their lifetime in the food and water

consumed. The Q1

*

 of 0.08 (mg/kg/day)-1 will be used for assessing dietary cancer risk, assuming a

linear approach.

Carcinogenic Occupational MOE Approach: 

The Agency’s Cancer Peer Review Committee recommended not to use the linear low dose

approach, but to utilize the MOE methodology for estimation of human risk. The MOE methodology

is consistent with a non-linear mechanism which requires continuous exposure. Thus, the likelihood

of a positive carcinogenic response depends on the duration of the exposure as well as the magnitude

of the exposure.

It is not appropriate to calculate a carcinogenic MOE for the occupational scenario, as there

are no chronic/long-term exposure scenarios for the application of alachlor. Calculation of a

carcinogenic MOE for agricultural workers based on intermittent exposure is not appropriate. 
48

Carcinogenic Occupational Q1

*

 Approach:

Unlike the MOE approach to carcinogenic risk assessment, the Q1

*

 approach assumes that

any exposure could result in tumor formation. Thus, this type of assessment could be performed for

an intermittent exposure. However, the scientific validity of the MOE approach for carcinogenic risk

assessment of alachlor has been documented. Alachlor was classified as “likely” to be a carcinogen

at high doses, but “not likely” at low doses. It is only the policy on determining an appropriate

regulatory level that has not been fully developed by the Agency. Since, performing a carcinogenic

MOE risk assessment for the occupational scenario is not appropriate, a Q1

*

 carcinogenic

occupational assessment for comparison purposes is not necessary.

e. Determination of the FQPA 10X Safety Factor

FQPA directs the Agency to "ensure that there is a reasonable certainty that no harm will

result to infants and children" from aggregate exposure to a pesticide chemical residue in setting and

reassessing tolerances. The law further states that in the case of threshold effects, for purposes of

providing this reasonable certainty of no harm, "an additional tenfold margin of safety for the

pesticide chemical residue and other sources of exposure shall be applied for infants and children to

take into account potential pre- and post-natal toxicity and completeness of the data with respect to

exposure and toxicity to infants and children. Notwithstanding such requirement for an additional

margin of safety, the Administrator may use a different margin of safety for the pesticide residue only

if, on the basis of reliable data, such margin will be safe for infants and children."

In determining what safety factor is appropriate for assessing risks to infants and children,

EPA considers all available reliable data and makes a decision using a weight-of-evidence approach.

This approach takes into account the completeness and adequacy of both the toxicity (hazard) and

exposure databases. 

The Agency’s FQPA Safety Factor Committee met on March 30, 1998, to evaluate both the

hazard and exposure databases for alachlor and determine the removal, retention, or reduction of the

FQPA Safety Factor (as required by FQPA), to ensure the protection of infants and children from

exposure to alachlor. Based on a weight of the evidence approach, the Committee determined that

the 10x Safety Factor for enhanced sensitivity to infants and children (as required by FQPA) should

be removed. This decision was based on the following information:

Hazard Consideration - Determination of Susceptibility

There is no evidence of increased susceptibility of rats or rabbits to in utero and/or postnatal

exposure to alachlor. In the prenatal developmental toxicity studies in rats and rabbits and the multigeneration reproduction study, effects in the offspring were not observed at levels which resulted in

evidence of parental toxicity. 
49

Hazard Consideration - Adequacy of the Toxicological Database

There are no data gaps for the assessment of the effects of alachlor following in utero and/or

postnatal exposure. Based on the toxicity profile for alachlor, a developmental neurotoxicity study

in rats is not required.

Exposure Consideration - Dietary (Food)

The established alachlor tolerances are expressed as “alachlor and its metabolites.” The

current enforcement method measures alachlor and its metabolites containing the DEA and HEEA

moieties. There are several other classes of alachlor metabolites that are not included in the tolerance

expression. 

Alachlor is a herbicide, generally used pre-emergence or early postemergence. Residues are

systemic. Rotational crop tolerances are needed indicating that residues remain in the soil for at least

a year after use. 

Anticipated residues were used in the alachlor chronic and carcinogenic dietary exposure

assessment. Anticipated residues for alachlor were based on the average residues found in field trials

where alachlor was used at the maximum typical application rate and weighted for the percent of use

at each application timing (i.e., preemergence vs. postemergence). Adequate information on percent

of crop treated is available for all crops. Up to 35% of corn and lima beans are treated, and up to 15

% of soybeans. Lesser amounts of other crops are treated (e.g., <5% of peanuts). These percentages

are down from 10 years ago (when 62% of peanuts were treated). 

Since the dietary exposure assessment is based on field trial data, the anticipated residues are

likely to overestimate the dietary exposure because application rates and timing assumed in the dietary

exposure analysis are conservative, and residues are likely to degrade after the farm gate where field

trial samples are obtained. Crops contributing most highly to the dietary exposure for both adults and

children were legumes (beans and soybeans) and milk, followed by corn. 

Exposure Consideration - Dietary (Drinking Water)

Estimates of alachlor concentrations in ground water are based on the National Alachlor Well

Water Survey (NAWWS). These samples represent approximately 6 million wells from which

approximately 20 million people draw their drinking water. Reported values are for alachlor per se.

No degradates of alachlor were analyzed in the NAWWS. NAWWS data are considered to be of

high quality, and because of the statistical design of the survey, are also considered to be the best

available data concerning alachlor per se residues in ground water.

Estimates of alachlor concentrations in surface water are also based on available monitoring

data. Additionally, in surface water, there is some monitoring data available for the alachlor ESA

degradate. Concentrations are reported as time weighted mean concentrations (TWMC) which
50

reflect "amortization" of periods of high and low concentrations. Therefore, annual TWMCs

(calculated using at least one year of sampling data) are the most appropriate values to use for

estimation of chronic exposure to alachlor in drinking water.

The information available to the Agency, a partial toxicological database, indicates that the

alachlor ESA degradate is of lower toxicity than the parent. But, the Agency does not have

toxicological databases on all degradates of alachlor. However, based on metabolism studies and

knowledge of the chemical structures of the degradates, the Agency does not believe that the toxicity

of the degradates would exceed that of alachlor. Therefore, the Agency will assume that structurally

similar alachlor degradates are no more or no less toxic than alachlor. The Agency has used the

available exposure data on alachlor and alachlor ESA to determine that 4% of the RfD is occupied

by food and water (children 1 - 6 years). Even if many of the alachlor degradates were present, it

is not likely that the RfD would be exceeded. 

Exposure Consideration - Residential (Non-occupational, Non-dietary) Uses

Alachlor is a restricted use pesticide; and therefore, can only be used by certified applicators

and cannot be purchased or used by the general public. The Agency has not identified any alachlor

products that are intended for residential use.

Decision of the FQPA 10X Safety Factor Committee

Based on their consideration of the above hazard and exposure databases, the Agency’s FQPA

10X Safety Factor Committee recommended that the 10x factor for enhanced sensitivity to infants

and children (as required by FQPA) should be removed. The rationale for this decision is

summarized below: 

# There was no indication of increased susceptibility of rats or rabbits to in utero and/or

postnatal exposure to alachlor. In the prenatal developmental toxicity studies in rats

and rabbits and the multi-generation reproduction study, effects in the offspring were

not observed at levels which resulted in evidence of parental toxicity.

# The toxicology data base for alachlor is complete. The toxicity profile does not

indicate the need for a developmental neurotoxicity study.

# The use of generally high quality data together with conservative models in the

exposure assessment provided adequate protection for infants and children.

# Alachlor is not currently registered for any residential uses.

3. Exposure Assessment

a. Dietary Exposure

The residue chemistry database includes information on the pesticide residues found in plants

and animals, the levels of the detected pesticide residues, and a description of the analytical methods
51

used. Residue chemistry data are used by the Agency to determine the residues of concern and to

establish tolerances in food and feed. Tolerances are pesticide residue levels that should not be

exceeded in or on a raw agricultural commodity in the channels of interstate commerce when the

pesticide is applied according to label directions. Tolerances for residues of alachlor in/on raw plant

commodities, and in animal commodities are currently expressed in terms of the combined residues

of alachlor and its metabolites (calculated as alachlor) (40 CFR §180.249). These tolerances are set

at 0.02-3.0 ppm. No food/feed additive tolerances have been established for alachlor residues of

concern. 

The residue chemistry database for alachlor is adequate and will support reregistration

eligibility. 

Nature of the Residue - Plants: OPPTS GLN 860.1300 (formerly 171-4a)

The qualitative nature of the residue in plants is adequately understood. Studies with corn

and soybeans indicate that alachlor is readily absorbed from soils and translocated throughout the

plant. Very little alachlor is translocated from the foliage. Metabolism involves the displacement of

chlorine by oxygen or sulfur nucleophiles, hydroxylation at the 1- position of the ethyl group, and

conjugation of the metabolites with sugar. The terminal residues to be regulated are those

metabolites which can be hydrolyzed under basic conditions to 2,6-diethylaniline (DEA) and 2-ethyl6-(1-hydroxyethyl)aniline (1-HEEA). (MRID Nos. 00026221, 00081314, 00131424).

The alachlor ESA metabolite was identified as one of many alachlor metabolites present in

these crops. Since alachlor ESA is converted to diethylaniline (DEA) by the alachlor crop residue

methodology, it has been quantified in the crop residue analyses conducted for alachlor and is

therefore included in the existing crop tolerances listed at 40 CFR § 180.249.

The chemical structures of representative metabolites are presented in Figure A. 
52

N

CH3

H C3

O

Cl

O

CH3

N

CH3

H C3

O

OH

O

CH3

Alachlor ESA

N

H

CH3

H C3

O

OH

OH

Figure A. The Chemical Structures of Representative Metabolites of Concern of Alachlor.

Common Name

Chemical Name Chemical Structure

alachlor

2-chloro-2',6'-diethyl-N-(methoxymethyl)acetanilide

alachlor alcohol metabolite (A-23)

N-[(2,6-diethyl)phenyl]-N-methoxymethyl2-hydroxyacetamide

alachlor ESA metabolite

MON 5775, 

2',6'-diethyl-N-methoxymethyl-2-sulfoacet

anilide, sodium salt or 2-[2,6-diethylphenyl

(methoxymethyl) amino]-2-oxoethane

sulfonic acid, sodium salt. 

A-11

N-{[2-ethyl-6-(1-hydroxyethyl)]phenyl}-2-

hydroxyacetamide
53

N

H

CH3

H C3

O

OH

O

N

H

CH3

H C3

O

OH

N

CH3

H C3

O

S

O

CH3

OH

CH3

O

O

N

H

CH3

H C3

O

OH

S

CH3

O

O

A-18

N-[(2,6-diethyl)phenyl]oxanilic acid

A-20/AP-7

N-[(2,6-diethyl)phenyl]-2-

hydroxyacetamide

alachlor sulfone metabolite (S-24) 

N-{[2-ethyl-6-(1-hydroxyethyl)phenyl}-Nmethoxymethyl-2-(methylsulfone)acetamide

S-16 

N-{[2-ethyl-6-(1-hydroxyethyl)]phenyl}-2-

(methyl-sulfone)acetamide

Nature of the Residue - Livestock: OPPTS GLN 860.1300 (formerly 171-4b)

The qualitative nature of the residue in animals is adequately understood. Studies involving

lactating goats and laying hens fed an alachlor alcohol or sulfone metabolite indicate that metabolism

of alachlor in hens and ruminants is similar. After displacement of chlorine, metabolites undergo loss

of the methoxymethyl group, hydroxylation of the ethyl side-chain(s) usually at the 1- position, and

formation of glucuronide conjugates. (MRID Nos. 00137777, 00137778, 00147472, 00147473,

40393901, 40394001, 42594901, 42594902, 42594903, 42594904)
54

In animals dosed with technical alachlor, alachlor's ESA metabolite was identified as a

metabolite of alachlor in rat, mice, or monkey metabolism studies. (MRID Nos. 00132045,

42852107, 42931101, 42852106, 00154238, 40000901). The initial chlorine displacement step

involving glutathione catalyzed by glutathione transferase has been firmly established in these

mammals. Methylsulfone and sulfur-conjugated organic acids have been shown to arise from further

metabolic conversion of the glutathione adduct in rats and monkeys. Although the initial metabolism

of alachlor in mammals is oxidative conversion of the sulfur atom, the metabolic product is not

alachlor ESA.

Livestock metabolism studies which included alachlor ESA as one of the dosed components

were performed (MRID Nos. 00147472, 00147473). Results from these experiments demonstrated

that alachlor ESA was excreted by the animals unchanged, largely via the feces (goats). It did not

accumulate in edible tissues. 

The residues to be regulated are those metabolites which can be hydrolyzed under basic

conditions to 2,6-diethylaniline (DEA) and 2-ethyl-6-(1-hydroxyethyl)aniline (1-HEEA). See Figure

A. 

Residue Analytical Methods: OPPTS GLN 860.1340 (formerly 171-4c,d) 

Three GLC methods, Methods I(a), I(b), and II, are currently available in the Pesticide

Analytical Manual (PAM) Vol. II for the enforcement of tolerances for alachlor residues of concern;

however, these methods do not recover 1-HEEA-yielding metabolites. An HPLC method, which

determines DEA- and 1-HEEA-yielding metabolites has been validated by the Agency and is

considered acceptable for enforcement purposes for plant commodities. The method uses HPLC with

oxidative coulometric electrochemical detection of both DEA- and 1-HEEA-producing residues, and

was recommended for inclusion in PAM Vol. II as Method III; the limit of detection is 0.01 ppm for

each metabolite class. (MRID Nos 00023663, 00093160, 00148285, 00149999, 00152197,

00154237, 00154332, 00155732, 00159793, 00159796, 00162939, 40039901, 40040301, 40040401,

40271801, 40271802, 40529201, 40558001, 40820601, 41916001, 42086001, 42192501, 42286701,

42286702, 42308701, 42349101, 43140001, and PP#9F0740)

Multiresidue Methods: OPPTS GLN 860.1360 (formerly 171-4m)

The FDA Pestrak database (PAM Vol. I, Appendix II, dated 11/90) indicates that alachlor,

per se, is completely recovered through Multiresidue Protocols D and E. In addition, multiresidue

protocol testing of five alachlor metabolites has been submitted and forwarded to FDA (MRID No.

41949601).

Storage Stability Data: OPPTS GLN 860.1380 (formerly 171-4e) 

Adequate storage stability data are available for corn, peanuts, soybeans and their processed

commodities, for sorghum, and for animal commodities. Residues of alachlor metabolites are stable
55

during frozen storage (<-18 oC) in/on corn forage and fodder, sorghum grain, forage, and fodder, and

soybeans for up to 1394 days. Residues of alachlor metabolites are stable during frozen storage in/on

sunflower seeds for up to 280 days and in the processed commodities of sunflowers for up to 91 days.

These storage stability data can be translated to all crops for which alachlor is currently registered.

(MRID Nos. 00149406, 00150090, 00152198, 00152868, 00154237, 40491101, 40628301,

40946901, and 42239501)

Crop Field Trials: OPPTS GLN 860.1500 (formerly 171-4k)

The conclusions regarding the reregistration eligibility of alachlor are based on the use

patterns registered by the basic producer, Monsanto Corporation. 

Some of the data used in support of existing or proposed tolerances were generated at Craven

Laboratories. The Agency determined that it would not rely on Craven data for regulatory decisions,

and identified the data that would need to be replaced. However, replacement of the Craven

generated magnitude of the residue data were not required for soybeans, provided postemergence and

sequential uses on soybeans were removed from all alachlor labels. At this time these use patterns

have been deleted from the label.

Data for magnitude of the residue in sorghum grain, forage, and fodder have been evaluated

and deemed adequate. Data are available to support the G formulation of alachlor on sweet corn

applied preplant incorporated and preemergence at up to 4 lb ai/A. Data are available to support the

use of the Mcap/G formulation on sweet corn: preemergence and preplant incorporated and

postemergence at 4 lb ai/A. Data have been submitted to support use of the Mcap formulation on

corn at 4 lb ai/A preemergence followed by 2 lb/A when used as a sequential application for early

postemergence (before the corn is 5" high). The maximum single application rate is 4 lb ai/A. 

Additional field residue data are no longer required for beans (dry and succulent), to support

pre-emergence uses; for field corn grain, forage, and stover, to support sequential uses of the EC

formulation; for sweet corn (K+CWHR) and sweet corn forage and stover to support postemergence

and sequential uses of the EC formulation and uses in excess of 4 lb ai/A/season; and for peanuts to

support postemergence and sequential uses. Monsanto has elected to delete these uses rather than

generate additional residue data at this time. The labels have been changed to reflect these changes.

The proposed tolerances for soybeans and soybean aspirated grain fractions must be revised;

higher tolerances are required. Tolerance petitions for bean vines and hay, corn forage and fodder,

peanuts, peanut hulls, and sorghum forage are pending. (MRID Nos. 00022988, 00023664,

00023665, 00024526, 00025262, 00026995, 00028556, 00028557, 00028558, 00035389, 00035390,

00035391, 00035395, 00035399, 00068044, 00068045, 00081311, 00147475, 00148285, 00152197,

00152199, 00155732, 00159793, 00159796, 00159936, 41083801, 40039901, 40040301, 40189701,

40271801, 40341201, 40502101, 40511201, 40511301, 40511901, 40662601, 40820601, 41083801,

41862901, 41916301, 42309001, 42313301, 42348901, 42348902, 42349101, 42741601, 42741601,

42929901, 42971701) 
56

Feeding restrictions have been established for peanut vines and hay, and soybean forage and

hay; therefore, the established tolerances for these commodities should be revoked. Note that

Monsanto will be submitting data to support sunflower and cotton. Tolerances will need to be

established for these commodities.

Processed Food/Feed: OPPTS GLN 1520 (formerly 171-4l)

 No food or feed additive tolerances for alachlor are needed on any processed product of any

commodity for which alachlor is currently registered. However, all data submitted for magnitude of

the residue in processed food/feed have been evaluated and deemed adequate. (MRID Nos.

00148285, 00152197, 00154239, 00154240, 00162937, 00162939, 40040401, 40271802, 40788201,

40947101, 41856301, 41862901, 41916301, 42302001, and PP#0F2313/FAP#1H5612)

Reduction of residue data were submitted for dry beans and peanuts as required by a June 9,

1986, DCI. Residues were determined in canned beans, peanut butter, dry and oil roasted peanuts

following commercial processing. A processing factor of 0.2x was determined for canning beans.

Processing factors of 0.70x, 0.75x, and 0.83x were determined for peanut butter, dry roasted peanuts,

and oil roasted peanuts, respectively. These factors will be used for the determination of anticipated

residues for alachlor.

Limited monitoring studies were submitted for peanut butter and infant soy formula. Three

major brands of peanut butter were collected in major cities across the US in 1989 in 2 studies. Of

the 192 samples collected, 89% had detectable residues of alachlor metabolites. The average residue

found was 0.029 ppm alachlor equivalents (with no correction for percent crop treated). In another

study, several samples of 2 major brands of soy formula were collected in 9 major cities across the

US. No detectable residues of alachlor DEA or HEEA metabolites were found (LOD=0.01 ppm) in

any of the 1,398 samples. (MRID Nos. 40330301, 40820601, 40820701, 42158601, 42276701,

42300701, 42309001).

Meat, Milk, Poultry and Eggs: OPPTS GLN 860.1480 (formerly 171-4j)

Data for magnitude of the residue in meat, milk, poultry, and eggs have been evaluated

previously; however, the adequacy of the data could not be assessed because at that time the

qualitative nature of the residue in animals was not adequately understood. These data were

generated from feeding studies in which dairy cattle and poultry were dosed with of a mixture of

DEA- and 1-HEEA-yielding metabolites (60% DEA-yielding and 40% 1-HEEA-yielding metabolites)

at approximately 4, 12, and 40 ppm. Tissues, milk, and eggs were analyzed for residues of DEA- and

1-HEEA-yielding metabolites and residues were expressed as alachlor equivalents. The maximum

residues of DEA-yielding metabolites were 0.9 ppb in milk, 1.0 ppb in fat, 6.2 ppb in kidney, 3.6 ppb

in liver, and 0.8 ppb in muscle, and the maximum residues of 1-HEEA-yielding metabolites were 1.6

ppb in milk, 1.5 ppb in fat, 5.4 ppb in kidney, 6.8 ppb in liver, and 1.1 ppb in muscle of dairy cattle

fed at approximately 12 ppm (1.7x the maximum expected dietary burden). The maximum residues

of DEA-yielding metabolites were 1.0 ppb in eggs, <0.5 ppb (nondetectable) in fat, 1.0 ppb in kidney,
57

1.1 ppb in liver, and <0.5 ppb in muscle, and the maximum residues of 1-HEEA-yielding metabolites

were 7.8 ppb in eggs, <0.5 ppb in fat, <1.0 ppb (nondetectable) in kidney, <1.0 ppb in liver, and 0.5

ppb in muscle of poultry fed at 4 ppm (approximately 2x the maximum expected dietary burden)

(MRID Nos. 00149406, 00150090, 00152198, and 00152868). 

These results support the established tolerances of 0.02 ppm for eggs; milk; and the fat, meat,

and meat byproducts of cattle, goats, hogs, horses, poultry and sheep. The maximum expected

dietary burdens of alachlor residues for cattle and poultry are calculated below; soybean forage and

hay, and peanut vines and hay were not included in this calculation since feeding restrictions have

been established for these commodities and tolerance revocations have been recommended. 

Table 7: Calculated Dietary Burdens

Commodity Percent in Diet Percent Dry Matter Tolerance1ppm 

(in diet)

Cattle:

Field corn grain 30 0.88 0.2 0.07

Bean vines 25 0.35 5 3.6

Soybean hulls 25 0.90 5 1.4

Soybean grain dust 20 0.85 10 2.4

 Dietary Burden Total = 7.5

Poultry:

Soybeans 50 -- 1 0.5

Soybean meal 20 -- 1 0.2

Soybean grain dust 20 -- 10 1.0

Corn Grain 10 -- 0.2 0.02 

 Dietary Burden Total = 1.8

1 In cases where tolerance proposals are required or pending, appropriate tolerance levels from

the Tolerance Reassessment Summary were used.

Water, Fish, and Irrigated Crops: OPPTS GLN 860.1400

Alachlor is not registered for direct use of water and aquatic food and feed crops; therefore,

no residue chemistry data are required under this guideline topic.

Food Handling: OPPTS GLN 860.1460

Alachlor is not registered for use in food-handling establishments; therefore, no residue

chemistry data are required under this guideline topic.
58

Confined Accumulation in Rotational Crops: OPPTS GLN 860.1850 (formerly 165-1)

All data for confined rotational crops have been evaluated and deemed adequate (MRID Nos.

42395301 and 42395302). Alachlor residues were found to accumulate in all three rotational crops

tested. Radishes, lettuce, and wheat were planted 31, 91, 120, or 365 days following the second of

two applications of uniformly ring-labeled [14C]-alachlor to sandy loam soil at 4 and 2 lb ai/acre (total

6 lb ai/A). Alachlor per se was not detected in the plants. The major classes of alachlor metabolites

found were those containing the DEA and 1-HEEA moities. 

Field Accumulation in Rotational Crops: OPPTS GLN 860.1900 (formerly 165-2)

Limited field rotational crop studies have been submitted (MRID No. 43442001). Soybeans

and wheat were planted at various plant-back intervals following preemergence application at 4 lb

ai/A (1x) and postemergence application at 2 lb ai/A (1x) of a representative 4 lb/gal Mcap

formulation to corn. The data indicate that residues of alachlor and its metabolites containing the

DEA and HEEA moieties exceed 0.01 ppm (the LOQ) in/on many raw agricultural commodities of

soybeans and wheat. Because quantifiable alachlor residues are present in/on rotational crops,

rotational crop tolerances need to be established, or the labels may be changed to prohibit rotation

to any crop not specified on the label. 

Soybeans and wheat can represent legume vegetables and cereal grains. Therefore, data

pertaining to field rotational crop studies are still required for a root crop and a leafy crop. Monsanto

plans to support cereal grains (except rice), and non-grass animal feeds as rotational crops. 

b. Dietary Exposure from Drinking Water

Alachlor is regulated under the SDWA (Safe Drinking Water Act). The MCL (Maximum

Contaminant Level) for alachlor is 2 ppb. An MCL is the maximum permissible level of a

contaminant in drinking water which is delivered to any user of a public water supply system. Water

systems are required to test for regulated chemicals on a quarterly basis. A public water supply is

considered in violation of the SDWA when the average of four consecutive monitoring events exceed

the MCL or a single event exceeds 4 times the MCL. Cost and the availability of treatment

technologies are also considered in promulgating an MCL, as well as the capability of available

laboratory facilities of measuring to a common analytical level. 

For the purposes of estimating human exposure through drinking water, the Agency has relied

on one groundwater study (NAWWS) and two surface water studies (ARP and USGS). (These

studies as well as other ground water and surface water studies are discussed in the Environmental

Assessment Section of this RED.) The NAWWS study was chosen because it is representative of

Midwestern use of alachlor. NAWWS data are considered to be of high quality, and because of the

statistical design of the survey are also considered to be the best available data concerning alachlor

perse residues in ground water and the population exposed to those residues. The USGS Survey was

used because of the detections of alachlor ESA. The ARP is the most recent as well as the most

extensive data on alachlor concentrations. The Acetochlor Registration Partnership (ARP) data was

collected at drinking water treatment facilities and is therefore finished water. The use of finished
59

water in this assessment is appropriate since (1) this is the water that is actually consumed, and (2)

generally surface water is treated before consumption. However, it is noted that the primary

treatment processes employed by most surface water drinking water supply systems are not expected

to be effective in removing alachlor. ARP data was collected for both ground and surface water sites.

However, the ARP ground water data has not yet been fully analyzed, and thus cannot be used in this

assessment. Additionally, it is believed that alachlor use is decreasing, so the most recent data would

reflect this decrease. 

Ground Water 

Estimates of alachlor concentrations in well or ground water were prepared by the Agency

and are based on the National Alachlor Well Water Survey (NAWWS). Monsanto conducted

NAWWS to estimate the proportions of private, rural domestic wells with detectable concentrations

of alachlor. NAWWS was a complex, statistically designed survey of alachlor occurrences which

targeted counties where alachlor was used in 1986. These samples represent approximately 6

million wells from which approximately 20 million people draw their drinking water.

Water samples were collected from 1,430 wells beginning in July 1988, and continuing

through May 1989. The samples were analyzed by GC/MS (gas chromatography using a mass

selective detector) in SIM (selected ion monitoring) mode. The limit of detection (LOD) for alachlor

was 0.03 ppb. 

Reported values are for alachlor per se. No degradates of alachlor were analyzed for in the

NAWWS. All "Non-detects" (values reported as ND) were averaged in (with the detected residues)

using 1⁄2 of the LOD, or 0.015 ppb. This is an acceptable procedure for dealing with the analytical

limits of detection for chemical residues. 

Table 8: NAWWS Data - Residue Levels for Use in Risk Assessment

Alachlor Residue Level

Detected in Ground Water

(ppb)

Estimate of the Population

Exposed

Percentage of the Population

Exposed

0.015

(These are non-detects - use

1⁄2 the LOD)

19,603,040 99.5

<0.2 63,249 0.32

>= 0.2 35,647 0.18

>2 3,000 0.015

The approximate proportion of the population in the alachlor use area exposed to the various

levels of alachlor in ground water is estimated above, using the data from the NAWWS. It was

estimated that 19,704,936 people received ground water from wells included in the survey area.
60

Surface Water 

Approximately 29 million people rely on surface water for their drinking water in the 11 major

corn-producing states. 

Alachlor can contaminate surface water at the time of application via spray drift or for several

weeks postapplication due to run-off. Alachlor surface water concentrations tend to peak in May to

early June during the first runoff events following application with rapid decline to approximately preapplication levels by July or August. Concentration of alachlor in surface water depends on numerous

factors including the quantity of alachlor used on the drainage area upstream, the infiltration

characteristics of the drainage area soils, and the timing, frequency, and intensities of post-application

runoff events. 

Degradates of alachlor were analyzed in one study, the USGS Reservoir Study. Alachlor per

se concentrations are reported as time weighted mean concentrations (TWMCs) which reflect

"amortization" of periods of high concentration and of low concentration. A TWMC is calculated

as follows: (1) Take the length of time from one measurement to the next and divide by two (For

the first and last measurements, the length of time between the first and second was assumed for the

first measurement and the time between the last and second to last measurement was assumed for the

last measurement); (2) Multiply the measurement by the number of days between each sample event;

and (3) Sum those results, then divide by the total number of days during which the measurements

occurred. Annual TWMCs (calculated using at least a year's worth of sampling data) are the most

appropriate values to use for estimation of chronic exposure to alachlor in drinking water because

TWMCs compensate for times of high and low contamination which occur during the year. 

USGS Midwestern Reservoir Study

In 1992 and 1993, USGS sampled 76 Midwestern reservoirs. Each reservoir was sampled

4 times each year. The samples were analyzed for both alachlor and alachlor ESA. The LOD for

alachlor was 0.05 ppb. The LOD for alachlor ESA was 0.03 ppb. The TWMC for the 2 year period

(90th percentile) for alachlor was 0.22 ppb, and for alachlor ESA was 3.00 ppb.

Acetochlor Registration Partnership (ARP) Data (1995-1996)

This is the most recent as well as the most extensive data on alachlor concentrations in surface

waters currently available. All of the data were collected at drinking water treatment facilities and

is therefore finished (treated) water. Samples were collected at 179 sites in 12 states (Delaware,

Illinois, Indiana, Iowa, Kansas, Maryland, Minnesota, Missouri, Nebraska, Ohio, Pennsylvania, and

Wisconsin) once every two weeks from April through September for both 1995 and 1996. Two to

three additional samples were collected at each site, one or two in the fall and the other in the winter.

Unfiltered samples were analyzed for alachlor using GC/MS. The LOD for the study was 0.02 ppb.

A TWMC was estimated by the Agency for each monitoring site in the ARP. These sites

were then ranked from highest to lowest. The 90th percentile TWMC for the 2 year period was 0.1
61

ppb. Thus, 10% of the monitoring sites have TWMCs greater than 0.1 ppb, and 90% of the

monitoring sites have TWMCs less than 0.1 ppb. 

Exposure Estimates

Adult Female

The exposure estimate for an adult female (13+ years) is calculated by the following

equation:

Exposure = (chemical concentration in μg/L in consumed water) X (10-3 mg/μg) ÷

(60 kg body weight) X (2L water consumed/day)

The 2 Liters of water is a default assumption used by the Agency. The 60 kilograms is the

Agency's default female body weight.

Adult Male

The exposure estimate for an adult male is calculated by the following equation:

Exposure = (chemical concentration in μg/L in consumed water) X (10-3 mg/μg) ÷

(70 kg body weight) X (2L water consumed/day)

The 2 Liters of water is a default assumption used by the Agency. The 70 kilograms is the

Agency's default male body weight.

Child (1 - 6 years)

The exposure estimate for a child (1- 6 years) is calculated by the following equation:

Exposure = (chemical concentration in μg/L in consumed water) X (10-3 mg/μg) ÷

(10 kg body weight) X (1L water consumed/day)

The 1 Liter of water is a default assumption used by the Agency. The 10 kilograms

is a default value for a child’s body weight. 

The other assumption used is assuming that water from the same source containing the same

contaminant level is consumed throughout a 70 year lifetime. Most of the US population moves at

some time during their life and does not live in the same area, drinking from the same water source

for a 70 year lifetime. It could be considered as either an over-estimation or an under-estimation of

risk depending on the contaminant levels in the other sources of drinking water.

Information on detections of the ESA degradate of alachlor was available for only one study -

the USGS Reservoir Study. Thus, for all other studies the exposure estimates should be considered
62

as under-estimated. The alachlor ESA degradate has been detected in Midwestern reservoirs and

streams at concentrations and frequencies that greatly exceed that of alachlor detections. 

Table 9: Drinking Water Exposure Estimates - Adult Male

STUDY Concentration

(ppb) 

Exposure

(mg/kg/day)

MCL 2 0.0000571

Surface Water

USGS - Alachlor (reservoir) 0.22 0.0000062

USGS - Alachlor ESA (reservoir) 3.00 0.0000857

ARP Data (1995-1996) (finished water) 0.1 0.0000028

Ground Water

NAWWS 0.2 0.0000057

NAWWS 0.015 0.0000004

Table 10: Drinking Water Exposure Estimates - Adult Female

STUDY Concentration

(ppb) 

Exposure

(mg/kg/day)

MCL 2 0.0000666

Surface Water

USGS - Alachlor (reservoir) 0.22 0.0000073

USGS - Alachlor ESA (reservoir) 3.00 0.0001

ARP Data (1995-1996) (finished water) 0.1 0.0000033

Ground Water

NAWWS 0.2 0.0000066

NAWWS 0.015 0.0000005

Table 11: Drinking Water Exposure Estimates - Child (1-6 years) 

STUDY Concentration

(ppb) 

Exposure

(mg/kg/day)

MCL 2 0.0002

Surface Water

USGS - Alachlor (reservoir) 0.22 0.000022

USGS - Alachlor ESA (reservoir) 3.00 0.0003

ARP Data (1995-1996) (finished water) 0.1 0.00001
63

Ground Water

NAWWS 0.2 0.00002

NAWWS 0.015 0.0000015

c. Occupational 

The Agency has not identified any alachlor products that are intended for home use.

Therefore, only an occupational assessment is required.

An occupational exposure assessment is required for an active ingredient if (1) certain

toxicological criteria are triggered and (2) there is potential exposure to handlers (mixers, loaders,

applicators; M/L/As) during use or to persons entering treated sites after application is complete.

In the case of alachlor the identification of short-term and intermediate-term endpoints triggers the

toxicological criteria and exposure to M/L/As has been identified.

As previously stated, there are no chronic (long-term) occupational exposure scenarios for

the application of alachlor. Therefore, a long-term exposure/risk assessment has not been performed.

Calculation of a carcinogenic MOE for agricultural workers based on intermittent exposure is not

appropriate. Therefore, in this occupational assessment for alachlor, the following scenarios are

considered: short-term and intermediate-term.

Use Patterns

Alachlor is a broad spectrum herbicide used on terrestrial food and feed crops and on

terrestrial non-food targets. The timing for applications is just prior to, at, or shortly after planting

(i.e., preplant, pre-emergent, at planting for corn and soybeans, post-transplant for ornamentals,

post-emergent, and at ground-crack for peanuts only).

Agricultural use sites include corn, soybeans, peanuts, grain sorghum (milo), and beans (i.e.

dry, lima, red kidney, and mung). Non-food and ornamental uses include applications to ornamental

woody shrubs and vines (i.e., junipers and yew). Alachlor is formulated as a liquid (active ingredient

25.2 to 45.1 percent), as a dry flowable (active ingredient 65 percent), as a microencapsulate (active

ingredient 41.5 percent) and as a granular (15 percent active ingredient). The maximum application

rates range from 4.0 lb ai/acre for corn to 3.0 lb ai/acre for soybean. Several of the application

methods involve soil incorporation techniques. Dry bulk fertilizers are impregnated with alachlor at

commercial fertilizer or farm chemical dealerships using specially designed, closed systems. In these

systems, alachlor and the fertilizers are mixed and blended in a system such as a closed rotary drum

container, or similar system. Nozzles situated inside the rotary drum are used to apply the alachlor

onto the fertilizer. The fertilizer impregnated with alachlor is then applied using spin-type spreaders,

or positive displacement equipment.
64

Incident Data

 Alachlor is considered a mild irritant according to EPA's "Recognition and Management of

Pesticide Poisoning" (Fourth Edition, 1989). No serious cases (deaths or hospitalized cases) have

been reported in national surveys of deaths (in the 1960s or 1970s, the last surveys completed) or

hospitalization (1971 through 1982). California reported just 3 physician-treated cases in the 12 year

period, 1982 through 1993. Two of these three cases involved skin or eye effects and one case was

considered a possible systemic poisoning. Thirteen unconfirmed cases have been screened by the

Office of Pesticide Program's Incident Data system, most of which reportedly experienced minor

dermal effects. No changes in labeling are warranted based on this incident data. 

Previous Agency Regulatory Action/ Special Review

At the time of the Special Review of alachlor the Agency used the best available data to

estimate worker exposure. Risk estimates for the PD-1 were based on patch data supplied by the

registrant which measured exposure to the EC, Mcap, and G formulations. However, in response

to the PD-1, the registrant submitted additional data; namely, the previously discussed 1984 and

1985 human biomonitoring data. The Agency reviewed these data. Numerous limitations were

identified related to the biomonitoring data, such as: (1) the small number of replicates (4 persons per

study) which cannot indicate the range (the expected variability) of exposure to alachlor; (2) study

subjects were Monsanto employees; (3) mixer/loaders wore protective goggles, rubber gloves, and

rubber overshoes; (4) applicators used enclosed cab tractors exclusively; (5) only 20 acres were

treated with alachlor-containing formulations instead of the 80 to 120 acres that could be expected

to be treated; (6) some products were soil incorporated; and (7) biological monitoring and passive

dosimetry were conducted concurrently on the same individual which may reduce the amount of

pesticide reflected in biomonitoring results. 

At the time of the PD-4, the biomonitoring data were the best data available, so the Agency

used the biomonitoring data to estimate exposure. In fact, the PD-4 stated that the Agency believed

that biomonitoring data from well-designed and executed studies, if supported by adequate

pharmacokinetic studies, provide a better measure of exposure than patch data. At the time of the

PD-4, the Agency used monkey data showing the rate and ratio of excreted alachlor metabolites to

interpret the results of the biomonitoring data.

Using the previously submitted patch data from the registrant, and data available in the

literature documenting exposure variability, the Agency estimated a range of exposures of two orders

of magnitude, with the biomonitoring data representing the low end of the range for exposure to

alachlor during mixing/loading and groundboom application. In 1987 the Agency believed the range

of exposures defined by the biomonitoring data, the patch data, and the open literature values more

accurately reflected applicator exposure estimates than the estimates that were used in the PD-1.

In this risk assessment for the purpose of the re-registration of alachlor, the Agency has used

data from PHED as well as the registrant-generated biomonitoring data. As noted previously

limitations were identified. Of particular significance were (1) the small number of replicates (4

persons per study), and (7) biological monitoring and passive dosimetry were conducted concurrently
65

on the same individual. The small number of replicates lowers the confidence level in the results;

however, the higher of the two values (0.0000126 mg/kg/lb ai.) was used in the assessment. The

concurrent monitoring is in all probability a small percent of the total amount of alachlor that could

be absorbed given the small surface areas of the patches. These data do not meet the Agency’s

guideline requirements (875.2600), for biological monitoring. 

During the 10 year interval since the PD-4, the Pesticide Handlers Exposure Database

(PHED; currently Version 1.1) was developed. PHED was developed by Health Canada, the

American Crop Protection Association, and EPA, and initially released for public use in 1992. PHED

is a comprehensive generic/surrogate exposure database containing a large number of measured

values of dermal and inhalation exposure for pesticide workers (e.g., mixers, loaders, and applicators)

involved in the handling or application of pesticides in the field. Use of surrogate or generic data is

appropriate since it is generally believed that the formulations and the method of application, not the

chemical properties of the pesticide control the amount of dermal and inhalation exposure. Thus,

PHED allows exposure and risk assessments to be conducted with a much larger number of

observations than available from a single exposure study. The current version of PHED (Version 1.1)

contains larger numbers of exposure replicates and a broader spectrum of mixer/loader and applicator

scenarios reflecting use of a variety of personal protective equipment. Note that Table 12 rates the

data (for number of replicates and quality control parameters) used to estimate exposure for mixing

liquids and groundboom application (baseline) as high confidence with the number of replicates

varying up to 122.

Generally, biomonitoring data are preferable to passive-dosimetry data. The use of a dermal

absorption factor is not necessary for biomonitoring data. Biomonitoring data can give a more

accurate estimate of absorbed dose. But, biomonitoring does not determine the source of the

exposure (inhalation/dermal; hands/head), and thus, cannot be used to identify what measures, to

mitigate exposures, are likely to be the most effective. 

Therefore, for the Alachlor Reregistration Eligibility Decision Document, the Agency is using

PHED Version 1.1 to assess pesticide handlers exposure to alachlor. However, the results of the

biomonitoring study will be used for comparison purposes. 

PHED is a comprehensive generic/surrogate exposure database containing a large number of

measured values of dermal and inhalation exposure for pesticide workers (e.g., mixers, loaders, and

applicators) involved in the handling or application of pesticides in the field. The database currently

contains data for over 2000 monitored exposure events. Use of surrogate or generic data is

appropriate since it is generally believed that the physical parameters of the handling and application

process (e.g. the type of formulations, the method of application, and the type of clothing), not the

chemical properties of the pesticide, control the amount of dermal and inhalation exposure. Thus,

PHED typically allows exposure and risk assessments to be conducted with a much larger number

of observations than available from a single exposure study. 

PHED also contains algorithms that allow the user to complete surrogate task-based exposure

assessments beginning with one of the four main data files contained in the system (i.e., mixer/loader,

applicator, flagger, and mixer/loader/applicator). Users select data from each file and construct
66

exposure scenarios that are representative of the use of the chemical. EPA, in conjunction with the

PHED task force, has evaluated all of the data currently in PHED, and developed a surrogate

exposure table that contains a series of standard exposure estimates for various scenarios. These

standard unit exposure values are the basis for this assessment. The standard exposure values (i.e.,

the unit exposure values included in the exposure and risk assessment tables) are based on the “best

fit” values calculated by PHED. PHED calculates “best fit” exposure values by assessing the

distributions of exposures for each body part included in datasets selected for the assessment (e.g.,

chest or forearm) and then calculating a composite exposure value representing the entire body.

PHED categorizes distributions as normal, lognormal, or in an “other” category. Generally, most data

contained in PHED are lognormally distributed or fall into the PHED “other” distribution category.

If the distribution is lognormal, the geometric mean for the distribution is used in the calculation of

the “best fit” exposure value. If the data are an “other” distribution, the median value of the dataset

is used in the calculation of the “best fit” exposure value. As a result, the surrogate unit exposure

values that serve as the basis for this assessment generally range from the geometric mean to the

median of the selected dataset.

The first step in performing a handler exposure assessment is to complete a baseline exposure

assessment. The baseline scenario generally represents a handler wearing long pants, a long-sleeved

shirt, and no chemical-resistant gloves. If, there is a level of concern, then increasing levels of risk

mitigation, such as PPE (personal protective equipment) and engineering controls, are used to achieve

an appropriate margin of exposure (MOE). 

Occupational Exposure Scenarios

The Agency has determined that there are potential exposures to mixers, loaders, applicators,

or other handlers during usual use-patterns associated with alachlor. Based on the use patterns, nine

major exposure scenarios were identified for alachlor: 

(1a) mixing/loading liquids for aerial and chemigation application; 

(1b) mixing/loading liquids for groundboom application; 

(2) mixing/loading granulars for drop type tractor drawn application; 

(3a) mixing/loading dry flowables for aerial application; 

(3b) mixing/loading dry flowables for groundboom application; 

(4) aerial application of liquids (fixed-wing); 

(5) aerial application of liquids (helicopter); 

(6) groundboom application of liquids; 

(7) granular drop type tractor drawn application; 

(8) mixing/loading and application to dry bulk fertilizer; and, 

(9) flaggers.

A summary and description of the caveats and parameters specific to each exposure scenario

is shown in Table 12.

Occupational Exposure Tables
67

Two types of assessments (short-term and intermediate-term) are required for evaluating

occupational risk assessment. The NOEL for estimating short-term risk is from a developmental

(oral) toxicity study, which requires the use of a dermal absorption factor (24%), and the average

body weight of a female (60 kg) is used in the assessment. The NOEL for estimating intermediateterm risk is from a dermal toxicity study; therefore, no dermal absorption factor is applied. The

demonstrated effects from that study are not sex-specific; therefore, the average body weight of

humans (70 kg) is used in the assessment. 

Table 13 shows the calculations of daily total exposure to alachlor: 

! with baseline attire (long-sleeve shirt, long pants, shoes, and socks). 

Table 14 shows the calculations of daily total exposure to alachlor:

! with the addition of personal protective equipment (chemical-resistant gloves and

double-layer clothing) 

Table 15 shows the calculations of daily total exposure to alachlor:

! with the use of engineering controls (closed systems for mixing and loading, closed

cabs/cockpits for applications and flagging). 

Tables 13, 14, and 15 show the calculations of occupational handler exposure for both the

short- and intermediate-term scenario. For the short-term assessment, each table includes a 24%

dermal absorption adjustment to the "daily dermal exposure" (column 6). This daily absorbed dermal

exposure (column 9) is added to the daily inhalation exposure (column 7) to calculate the daily

absorbed total exposure (column 10). This exposure calculation (column 10 in Tables 13, 14, and

15) is used to assess the short-term risk in Table 28. For the intermediate-term assessment, "daily

dermal exposure" (column 6) is added to "daily inhalation exposure" (column 7) to calculate the

"daily total exposure" (column 8). This exposure calculation (column 8 in Tables 10, 11, and 12 is

used to assess the intermediate-term risk in Table 29.

Table 16 is data from the registrant-submitted biomonitoring study.

In Table 14, the level of personal protective equipment (PPE) added (i.e., only chemicalresistant gloves or double-layer body protection plus chemical-resistant gloves) varies among the

exposure scenarios based on whether the eventual margins of exposures (MOEs) would be 100 or

greater solely with the addition of gloves. 

In Table 28, "baseline absorbed total dose" (column 3) is calculated by dividing the value in

Table 13 "daily absorbed total exposure" (column 10) by the average female body weight (60 kg).

Similarly, in Table 28 "PPE daily total dose" (column (5) is calculated by dividing the value in Table

14 "PPE daily absorbed total exposure" (column 10) by 60 kg. Finally, in Table 28 "Eng. C daily

total dose" (column 7) is calculated by dividing the value in Table 15 "Eng. C daily absorbed total

exposure" (column 10) by 60 kg.

In Table 29, "baseline total dose" (column 3) is calculated by dividing the value in Table 13

"baseline daily total exposure" (column 8) by the average human body weight (70 kg). Similarly, in

Table 29 "PPE daily total dose" (column 5) is calculated by dividing the value in Table 14 "PPE daily
68

total exposure" (column 8) by 70 kg. Finally, in Table 29 "Eng. C daily total dose" (column 7) is

calculated by dividing the value in Table 15 "Eng. C daily total exposure" (column 8) by 70 kg.

Further explanation of the calculations are in the footnotes.
69

Table 12: Exposure Scenario Descriptions for Uses of Alachlor 

Exposure Scenario (Number)

Data Source

Daily Acres 

Treateda

Commentsb

Mixer/Loader Exposure

Mixing/Loading Liquid (1a and b) PHED V1.1 80 acres groundboom;

350 acres aerial and

chemigation

Baseline: "Best Available" grades: Hands, dermal, and inhalation acceptable grades. 

Hands = 53 replicates; Dermal = 25 to 122 replicates; Inhalation = 85 replicates. High

confidence in dermal data; high confidence in inhalation data.

PPE: "Best Available" grades: Hands and dermal acceptable grades. Hands = 59

replicates; Dermal = 25 to 122 replicates. High confidence in dermal and inhalation data.

Engineering Controls: "Best Available" grades: Dermal and inhalation acceptable

grades. Hands = 31 replicates, Dermal = 16 to 22 replicates; Inhalation = 27 replicates. 

High confidence in dermal and inhalation data.

PHED data used for baseline and engineering controls, no Protection Factor (PF) were

necessary. Fifty percent PF was used for coveralls (PPE). 

Mixing/Loading Granulars (2) PHED V1.1 80 acres Baseline: "Best Available" grades: Hands all grades, dermal and inhalation acceptable

grades. Dermal = 29 to 36 replicates; inhalation = 58 replicates; and hands = 10 replicates. 

Low confidence in dermal data, high confidence in inhalation data.

PHED data used for baseline, no PFs were necessary. 

Mixing/Loading Dry Flowables (3a and 3b) PHED V1.1 80 acres Baseline: "Best Available" grades: Hands grades A,B, C; dermal and inhalation acceptable

grades. Dermal = 16 to 26 replicates; inhalation = 23 replicates; and, hands = 7 replicates. 

Low confidence in dermal data, high confidence in inhalation data.

PPE: "Best Available" grades: Hands, dermal and inhalation acceptable grades. Hands =

21 replicates; Dermal = 16 to 26 replicates, inhalation = 23 replicates. High confidence in

dermal and inhalation data.

PHED data used for baseline, no PFs were necessary. Fifty percent PF was used for

coveralls (PPE).

Applicator Exposure

Aerial equipment--fixed wing enclosed cab (liquids) (4) PHED V1.1 350 acres Engineering Controls: "Best Available" grades: Hands acceptable grades, dermal and

inhalation grades A,B,C. Hands = 34 replicates; Dermal = 24 to 48 replicates; Inhalation =

23 replicates. Medium confidence in dermal and inhalation data.

PHED data used for engineering controls, no PFs were necessary.
Table 12: Exposure Scenario Descriptions for Uses of Alachlor 

Exposure Scenario (Number)

Data Source

Daily Acres 

Treateda

Commentsb

70

Aerial equipment--helicopter enclosed cab (liquids) (5) PHED V1.1 350 acres Engineering Controls: "Best Available" grades: dermal grades A,B,C; inhalation grades

"acceptable". Hands = 2 replicates, Dermal = 3 replicates; Inhalation = 3 replicates. Low

confidence in dermal and inhalation data.

PHED data used for engineering controls, no PFs were necessary.

Groundboom Application (liquids) (6) PHED V1.1 80 acres Baseline: "Best Available" grades: Hands, dermal, and inhalation acceptable grades. 

Hands = 29 replicates; Dermal = 32 to 42 replicates; Inhalation = 22 replicates. High

confidence in dermal and inhalation data.

PPE: "Best Available" grades: Hands grades ABC and dermal acceptable grades. Hands =

21 replicates Dermal = 32 to 42 replicates Medium confidence in dermal data; high

confidence in inhalation data.

Engineering Controls: "Best Available" grades: Hands, and dermal = ABC grades;

Inhalation = acceptable grades. Hands = 16 replicates Dermal = 20 to 31 replicates;

Inhalation = 16 replicates. Medium confidence in dermal data; high confidence in

inhalation. 

PHED data used for baseline and engineering controls, no PFs were necessary. Fifty percent

PF was added for coveralls for PPE. 

Granular Drop Type Tractor Drawn Spreader

Application (7)

PHED V1.1 80 acres Baseline: "Best Available" grades: Hand, dermal and inhalation acceptable grades. 

Dermal = 4 to 5 replicates; hands = 5 replicates; inhalation = 5 replicates. Low confidence

in dermal and inhalation data.

PHED data was used for baseline, no PFs were necessary. 

Mixer/Loader/Applicator

Mixing/Loading and Application for Dry Bulk Fertilizer

(8)

No data No data No data

Flaggers

Flaggers for Aerial Applications (9) PHED V1.1 350 acres Baseline: "Best Available" grades: Hand, dermal and inhalation acceptable grades. 

Dermal = 16 to 18; hands = 16; inhalation = 18. High confidence in dermal, hand and

inhalation data.

PHED data was used for baseline, no PFs were necessary.

a Daily acres treated are from EPA estimates of acreage that could be treated in a single day for each exposure scenario of concern. 

b These grades are based on Quality Assurance/Quality Control data provided as part of the exposure studies. A replicate refers to data acquired during one complete work cycle. "Best Available" grades are defined by EPA SOP for meeting

Subdivision U Guidelines. Best available grades are assigned as follows: matrices with grades A and B data and a minimum of 15 replicates; if not available, then grades A, B, and C data and a minimum of 15 replicates; if not available,

then all data regardless of the quality and number of replicates. Data confidence are assigned as follows:

High confidence = grades A and B and 15 or more replicates per body part

Medium confidence = grades A, B, and C and 15 or more replicates per body part

Low confidence = grades A, B, C, D, and E or any combination of grades with less than 15 replicates 
71

Table 13: Alachlor Exposure Estimates to be Used in Short-Term and Intermediate-Term Risk Assessments - Baseline PHED Values

Exposure Scenario 

(Scenario #)

Baseline Dermal

Unit Exposure

(mg/lb ai)a

Baseline

Inhalation Unit

Exposure

 (mg/lb ai)b

Crop and 

Application Rate 

(lb ai/acre)c

Daily Acres

Treatedd

Daily

Dermal

Exposure

(mg/day)e

Daily Inhalation

Exposure

(mg/day)e

Baseline

Daily Total

Exposure

(mg/day)f

Daily

Absorbed

Dermal

Exposure

(mg/day)g

Baseline

Daily

Absorbed

Total

Exposure

(mg/day)h

Mixer/Loader Exposure

Mixing/Loading Liquids for Aerial

Application and Chemigation (1a)

2.9 0.0012 Corn 4.0 350 4,060 1.68 4,061.7 974 976

Soybeans 3.0 3,045 1.26 3,046.3 731 732

Mixing/Loading Liquids for Groundboom

Application (1b)

Corn 4.0 80 928 0.384 928.4 223 223

Soybeans 3.0 696 0.288 696.3 167 167

Mixing/Loading Granulars for Drop Type

Tractor Drawn Spreaders (2)

0.0076 0.0017 Corn 4.0 80 2.4 0.544 2.9 0.58 1.1

Soybeans 3.0 1.8 0.408 2.2 0.43 0.83

Mixing/Loading Dry Flowables for Aerial

Application (3a)

0.07 0.00077 Corn 4.0 350 98 1.08 99.08 24 25

Soybeans 3.0 73.5 0.81 74.31 18 18

Mixing/Loading Dry Flowables for

Groundboom Application (3b)

Corn 4.0 80 22.4 0.25 22.65 5.4 5.6

Soybeans 3.0 16.8 0.19 16.99 4.0 4.2

Applicator Exposure

Aerial Application of Liquids - Fixed-Wing

Aircraft - Enclosed Cockpit (4)

See Engineering

Controls

See Engineering

Controls

Corn 4.0 350 See

Engineering

Controls

See Engineering

Controls

See

Engineering

Controls

See

Engineering

Controls

See

Engineering

Soybeans 3.0 Controls

Aerial Application of Liquids - Helicopter

Aircraft - Enclosed Cockpit (5)

See Engineering

Controls

See Engineering

Controls

Corn 4.0 350 See

Engineering

Controls

See Engineering

Controls

See

Engineering

Controls

See

Engineering

Controls

See

Engineering

Soybeans 3.0 Controls

Groundboom Application of Liquids - (6) 0.015 0.0007 Corn 4.0 80 4.8 0.224 5.02 1.2 1.4

Soybeans 3.0 3.6 0.168 3.77 0.86 1.0

Granular Drop Type Tractor Drawn

Spreader Application (7)

0.01 0.00022 Corn 4.0 80 3.2 0.07 3.3 0.77 0.84

Soybeans 3.0 2.4 0.053 2.5 0.58 0.63

Mixer/Loader/Applicator Exposure

Mixing/Loading and Application of

Impregnated Dry Bulk Fertilizer (8)

See text

Flaggers
Table 13: Alachlor Exposure Estimates to be Used in Short-Term and Intermediate-Term Risk Assessments - Baseline PHED Values

Exposure Scenario 

(Scenario #)

Baseline Dermal

Unit Exposure

(mg/lb ai)a

Baseline

Inhalation Unit

Exposure

 (mg/lb ai)b

Crop and 

Application Rate 

(lb ai/acre)c

Daily Acres

Treatedd

Daily

Dermal

Exposure

(mg/day)e

Daily Inhalation

Exposure

(mg/day)e

Baseline

Daily Total

Exposure

(mg/day)f

Daily

Absorbed

Dermal

Exposure

(mg/day)g

Baseline

Daily

Absorbed

Total

Exposure

(mg/day)h

72

Flaggers for Aerial Applications (9) 0.01 0.00028 Corn 4.0 350 14.0 0.39 14.39 3.4 3.8

Soybeans 3.0 10.5 0.29 10.79 2.5 2.8

a Baseline dermal unit exposure represents long pants, long sleeve shirts, no gloves, open mixing/loading, open cabs or cockpits. Note that data on open cockpit aerial applications are not available. 

b Baseline inhalation exposure represents no respirator.

c Application rate comes from maximum values found in the alachlor labels EPA Reg Nos. 524-344, 524-403, 524-418, 524-422 and 524-314.

d Daily acres treated are from EPA estimates of acreage that could be treated in a single day for each exposure scenario of concern.

e Daily exposure (mg/day) = Exposure (mg/lb ai) * Appl. rate (lb ai/A) * Acres Treated.

f Total daily exposure (mg/day) = daily dermal exposure (mg/day) + daily inhalation exposure (mg/day). Note that this exposure number is used for the intermediate-term scenario only since the NOEL for calculating the MOE is from

a dermal study and the use of the dermal absorption factor is not necessary.

g Daily absorbed dermal exposure (mg/day) = daily dermal exposure (mg/day) * dermal absorption factor (0.24)

h Total absorbed daily exposure (mg/day) = daily absorbed dermal exposure (mg/day) + daily inhalation exposure (mg/day) Note that this exposure is used for the short-term scenario only since the NOEL

for calculating the MOE is from an oral study and it was necessary to use the dermal absorption factor. 
73

Table 14: Alachlor Exposure Estimates to be used in Short-Term and Intermediate-Term Risk Assessments - 

PHED Personal Protective Equipment (PPE) Values

Exposure Scenario 

(Scenario #)

PPE Dermal

Unit

Exposure

(mg/lb ai)a

Baseline

Inhalation Unit

Exposure

 (mg/lb ai)b

Crop and Application

Rate (lb ai/acre)c

Daily

Acres

Treatedd

Daily Dermal

Exposure

(mg/day)e

Daily Inhalation

Exposure

(mg/day)e

PPE Daily 

Total

Exposure 

(mg/day)f

Daily

Absorbed

Dermal

Exposure

(mg/day)g

PPE Daily

Absorbed

Total

Exposure

(mg/day)h

Mixer/Loader Exposure

Mixing/Loading Liquids for Aerial

Application and Chemigation (1a) 

0.043 0.0012 Corn 4.0 350 60.2 1.7 61.9 14.4 16.1

Soybeans 3.0 45.2 1.3 46.5 10.8 12.1

Mixing/Loading Liquids for Groundboom

Application (1b) 

0.043 0.0012 Corn 4.0 80 13.8 0.38 14.2 3.3 3.7

Soybeans 3.0 9.6 0.29 9.9 2.3 2.6

Mixing/Loading Granulars for Drop Type

Tractor Drawn Spreaders (2)

n/a n/a Corn 4.0 80 n/a n/a n/a n/a n/a

Soybeans 3.0 n/a n/a n/a n/a n/a

Mixing/Loading Dry Flowables for Aerial

Application (3a)

0.04 0.00077 Corn 4.0 350 56 1.1 57.1 13.4 14.5

Soybeans 3.0 42 0.81 42.8 10.1 10.9

Mixing/Loading Dry Flowables for

Groundboom Application (3b)

n/a n/a Corn 4.0 80 n/a n/a n/a n/a n/a

Soybeans 3.0 n/a n/a n/a n/a n/a

Applicator Exposure

Aerial Application of Liquids - Fixed-Wing

Aircraft - Enclosed Cockpit (4)

See

Engineering

Controls

See Engineering

Controls

Corn 4.0 350 See Engineering

Controls

See Engineering

Controls

See

Engineering

Controls

See

Engineering

Controls

See

Engineering

Soybeans 3.0 Controls

Aerial Application of Liquids - Helicopter

Aircraft - Enclosed Cockpit (5)

See

Engineering

Controls

See Engineering

Controls

Corn 4.0 350 See Engineering

Controls

See Engineering

Controls

See

Engineering

Controls

See

Engineering

Controls

See

Engineering

Soybeans 3.0 Controls

Groundboom Application of Liquids - (6) n/a n/a Corn 4.0 80 n/a n/a n/a n/a n/a

Soybeans 3.0 n/a n/a n/a n/a n/a

Granular Drop Type Tractor Drawn

Spreader Application (7)

n/a n/a Corn 4.0 80 n/a n/a n/a n/a n/a

Soybeans 3.0 n/a n/a n/a n/a n/a

Mixer/Loader/Applicator Exposure

Mixing/Loading and Application of

Impregnated Dry Bulk Fertilizer (8)

See text
Table 14: Alachlor Exposure Estimates to be used in Short-Term and Intermediate-Term Risk Assessments - 

PHED Personal Protective Equipment (PPE) Values

Exposure Scenario 

(Scenario #)

PPE Dermal

Unit

Exposure

(mg/lb ai)a

Baseline

Inhalation Unit

Exposure

 (mg/lb ai)b

Crop and Application

Rate (lb ai/acre)c

Daily

Acres

Treatedd

Daily Dermal

Exposure

(mg/day)e

Daily Inhalation

Exposure

(mg/day)e

PPE Daily 

Total

Exposure 

(mg/day)f

Daily

Absorbed

Dermal

Exposure

(mg/day)g

PPE Daily

Absorbed

Total

Exposure

(mg/day)h

74

Flaggers

Flaggers for Aerial Applications (9) n/a n/a Corn 4.0 350 acres n/a n/a n/a n/a n/a

Soybeans 3.0 n/a n/a n/a n/a n/a

n/a No longer necessary to carry scenario through analysis as exposure in baseline scenario is sufficiently low to calculate an MOE that will exceed 100 

a Scenario 1a and 1b single layer clothing and chemical resistant gloves, open mixing/loading

 Scenario 3a: open mixing/loading, double layer of clothing and chemical resistant gloves.

b Baseline inhalation exposure represents no respirator.

c Application rate comes from maximum values found in the alachlor labels EPA Reg Nos. 524-344, 524-403, 524-418, 524-422 and 524-314.

d Daily acres treated are from EPA estimates of acreage that could be treated in a single day for each exposure scenario of concern.

e Daily exposure (mg/day) = Exposure (mg/lb ai) * Appl. rate (lb ai/A) * Acres Treated.

f Total daily exposure (mg/day) = daily dermal exposure (mg/day) + daily inhalation exposure (mg/day). Note that this exposure number is used for the intermediate-term scenario only since the NOEL for calculating the MOE is from

a dermal study and the use of the dermal absorption factor is not necessary.

g Daily absorbed dermal exposure (mg/day) = daily dermal exposure (mg/day) * dermal absorption factor (0.24)

h Total absorbed daily exposure (mg/day) = daily absorbed dermal exposure (mg/day) + daily inhalation exposure (mg/day) Note that this exposure is used for the short-term scenario only since the NOEL

for calculating the MOE is from an oral study and it was necessary to use the dermal absorption factor. 
75

Table 15: Alachlor Exposure Estimates to be Used in Short-Term and Intermediate-Term Risk Assessments - Engineering Control 

(Eng C) PHED Values

Exposure Scenario 

(Scenario #)

Eng C

Dermal Unit

Exposure

(mg/lb ai)a

Baseline

Inhalation Unit

Exposure

 (mg/lb ai)b

Crop and Application

Rate (lb ai/acre)c

Daily

Acres

Treatedd

Eng C Daily

Dermal

Exposure

(mg/day)e

Daily Inhalation

Exposure

(mg/day)e

Eng C

Daily Total

Exposure

(mg/day)f

Eng C Daily

Absorbed

Exposure

(mg/day)g

Eng C

Daily

Absorbed

Total

Exposure

(mg/day)h

Mixer/Loader Exposure

Mixing/Loading Liquids for Aerial

Application and Chemigation (1a)

0.009 0.00008 Corn 4.0 350 9.8 0.11 9.9 2.4 2.5

Soybeans 3.0 7.4 0.08 7.5 1.8 1.9

Mixing/Loading Liquids for Groundboom

Application (1b)

Corn 4.0 80 2.2 0.026 2.2 0.54 0.57

Soybeans 3.0 1.7 0.02 1.7 0.4 0.42

Mixing/Loading Granulars for Drop Type

Tractor Drawn Spreaders (2)

n/a n/a Corn 4.0 80 n/a n/a n/a n/a n/a

Soybeans 3.0 n/a n/a n/a n/a n/a

Mixing/Loading Dry Flowables for Aerial

Application (3a)

No data No data Corn 4.0 350 No data No data No data No data No data

Soybeans 3.0 No data No data No data No data No data

Mixing/Loading Dry Flowables for

Groundboom Application (3b)

n/a n/a Corn 4.0 80 n/a n/a n/a n/a n/a

Soybeans 3.0 n/a n/a n/a n/a n/a

Applicator Exposure

Aerial Application of Liquids - Fixed-Wing

Aircraft - Enclosed Cockpit (4)

0.005 0.000068 Corn 4.0 350 7 0.095 7.1 1.7 1.8

Soybeans 3.0 5.3 0.07 5.3 1.3 1.4

Aerial Application of Liquids - Helicopter

Aircraft - Enclosed Cockpit (5)

0.0021 0.0000018 Corn 4.0 350 3.0 0.003 3.0 0.7 0.7

Soybeans 3.0 2.2 0.002 2.2 0.53 0.53

Groundboom Application of Liquids - (6) n/a n/a Corn 4.0 80 n/a n/a n/a n/a n/a

Soybeans 3.0 n/a n/a n/a n/a n/a
Table 15: Alachlor Exposure Estimates to be Used in Short-Term and Intermediate-Term Risk Assessments - Engineering Control 

(Eng C) PHED Values

Exposure Scenario 

(Scenario #)

Eng C

Dermal Unit

Exposure

(mg/lb ai)a

Baseline

Inhalation Unit

Exposure

 (mg/lb ai)b

Crop and Application

Rate (lb ai/acre)c

Daily

Acres

Treatedd

Eng C Daily

Dermal

Exposure

(mg/day)e

Daily Inhalation

Exposure

(mg/day)e

Eng C

Daily Total

Exposure

(mg/day)f

Eng C Daily

Absorbed

Exposure

(mg/day)g

Eng C

Daily

Absorbed

Total

Exposure

(mg/day)h

76

Granular Drop Type Tractor Drawn

Spreader Application (7)

n/a n/a Corn 4.0 80 n/a

n/a

n/a

n/a

n/a

n/a

n/a n/a

Soybeans 3.0

Mixer/Loader/Applicator Exposure

Mixing/Loading and Application of

Impregnated Dry Bulk Fertilizer (8)

See text

Flaggers

Flaggers for Aerial Applications (9) n/a n/a Corn 4.0 350 acres n/a n/a n/a n/a n/a

Soybeans 3.0 n/a n/a n/a n/a n/a

n/a No longer necessary to carry scenario through analysis as exposure in baseline scenario or with addition of PPE is sufficiently low to calculate an MOE that will exceed 100 

a Engineering controls dermal unit exposure represents long pants, long sleeve shirts, closed mixing/loading, closed cab tractor.

 Scenarios 1a: chemical resistant gloves. 

 Scenarios 4 and 5: closed cockpit single layer clothing, and no gloves.

b Baseline inhalation exposure represents no respirator.

c Application rate comes from maximum values found in the alachlor labels EPA Reg Nos. 524-344, 524-403, 524-418, 524-422 and 524-314.

d Daily acres treated are from EPA estimates of acreage that could be treated in a single day for each exposure scenario of concern.

e Daily exposure (mg/day) = Exposure (mg/lb ai) * Appl. rate (lb ai/A) * Acres Treated.

f Total daily exposure (mg/day) = daily dermal exposure (mg/day) + daily inhalation exposure (mg/day). Note that this exposure number is used for the intermediate-term scenario only since the NOEL for calculating the MOE is from

a dermal study and the use of the dermal absorption factor is not necessary.

g Daily absorbed dermal exposure (mg/day) = daily dermal exposure (mg/day) * dermal absorption factor (0.24)

h Total absorbed daily exposure (mg/day) = daily absorbed dermal exposure (mg/day) + daily inhalation exposure (mg/day) Note that this exposure is used for the short-term scenario only since the NOEL

for calculating the MOE is from an oral study and it was necessary to use the dermal absorption factor. 
77

Table 16: Alachlor Exposure Estimates to be Used in Short-Term and Intermediate-Term

Risk Assessments - Values from Registrant-Submitted Biomonitoring Studies 

Exposure Scenario 

(Scenario #)

Biomonitoring

Internal Estimated

Exposure

(mg/kg/lb ai)a

Adjusted

Biomonitoring

Internal

Estimated

Exposure

(mg/kg/lb ai)b

Crop and Application

Rate (lb ai/acre)c

Daily

Acres

Treatedd

Biomonitoring

Internal Dose

(mg/kg/day)e

Mixer/Loader Exposure

Mixing/Loading Liquids for Aerial

Application and Chemigation (1a)

0.0000126 n/a Corn 4.0 350 0.01764

Mixing/Loading Liquids for

Groundboom Application (1b)

Corn 4.0 80 0.004032

Mixing/Loading Granulars for Drop

Type Tractor Drawn Spreaders (2)

n/a 0.0000000647 Corn 4.0 80 0.0000207

Mixing/Loading Dry Flowables for

Aerial Application (3a)

n/a 0.000000316 Corn 4.0 350 0.0004424

Mixing/Loading Dry Flowables for

Groundboom Application (3b)

n/a 0.00000032 Corn 4.0 80 0.0001024

Applicator Exposure

Aerial Application of Liquids - FixedWing Aircraft - Enclosed Cockpit (4)This scenario not performed for biomonitoring data

Aerial Application of Liquids -

Helicopter Aircraft - Enclosed Cockpit

(5)

This scenario not performed for biomonitoring data

Groundboom Application of Liquids -

(6)

0.0000126 n/a Corn 4.0 80 0.004032

Granular Drop Type Tractor Drawn

Spreader Application (7)

n/a 0.00000767 Corn 4.0 80 0.002454

Mixer/Loader/Applicator Exposure

Mixing/Loading and Application of

Impregnated Dry Bulk Fertilizer (8)

This scenario not performed for biomonitoring data

Flaggers

Flaggers for Aerial Applications (9) This scenario not performed for biomonitoring data

n/a = not applicable
78

a Biomonitoring internal estimated exposure represents Monsanto employees who wore long pants, long sleeve shirts, elbow length rubber gloves, caps, goggles, open mixing/loading, no respirator, closed cab tractor.

b The biomonitoring studies were conducted with liquid formulations. Therefore, these internal estimated exposures are not appropriate for use with granular or dry flowable formulations. In an attempt to estimate the internal estimated

exposure a ratio of PHED exposure values that have been converted to baseline absorbed total doses were used in a ratio of other formulation/liquid formulation. The alachlor baseline absorbed total doses are from Table 25.

Scenario 2: (0.0000126 mg/kg/lb ai )( 0.019/3.7) = 0.0000000647 mg/kg/lb ai 

Scenario 3a: (0.0000126 mg/kg/lb ai )(0.41/16.3) = 0.000000316 mg/kg/lb ai 

Scenario 3b: (0.0000126 mg/kg/lb ai )(0.094/3.7) = 0.00000032 mg/kg/lb ai 

Scenario 7: (0.0000126 mg/kg/lb ai )(0.014/0.023) = 0.00000767 mg/kg/lb ai 

c Application rate comes from the application rate of 4 lbs ai used in the Monsanto study. 

d Daily acres treated are from EPA estimates of acreage that could be treated in a single day for each exposure scenario of concern.

e Biomonitoring internal dose (mg/kg/day) = Biomonitoring internal estimated exposure (mg/kg/lb ai) * Appl. rate (4 lb ai/A) * Acres Treated/day.
79

Post Application Exposure

The potential for post-application worker exposure is low, provided the Restricted Entry

Interval (12 hours) is observed. This is due to the timing of applications. Alachlor is applied to the

soil and/or soil incorporated preplant, pre-emergent, at planting for corn and soybeans, posttransplant for ornamentals, early post-emergent on corn, and at ground-crack for peanuts. This is

well before the plants are mature, which mitigates the potential for post-application exposure.

Exposure to alachlor during harvesting, even with sweet corn harvesting or seed corn detasseling, is

not likely to occur as alachlor is applied primarily preplant and pre-emergent. Therefore, the Agency

does not require that any post-application exposure or residue dissipation monitoring data be

generated to support the reregistration of alachlor.

4. Risk Characterization

a. Dietary

As previously stated, an acute dietary risk assessment is not required. The RfD of 0.01

mg/kg/day was used for calculating chronic dietary risk. For calculating carcinogenic dietary risk two

NOELs (14 mg/kg/day for stomach tumors and 0.5 mg/kg/day for nasal tumors) was used.

The tolerances used in this analysis are listed in Table 78: Tolerance Reassessment. At the

time that the dietary assessment was performed, the registrant had expressed interest in supporting

rotational crop tolerances for cotton and sunflowers. For this reason these uses were included in the

assessment at the tolerance levels that were recently revoked. However, in alachlor petition 8F5000

dated June 25, 1998, Monsanto is requesting to establish tolerances for the direct application of

alachlor to cotton and sunflower. This petition is now in review.

The consumption information used in this analysis is derived from USDA's 1977-78

Nationwide Food Consumption Survey (NFCS). Over 30,000 respondents were surveyed over three

days as to what foods they ate, with each individual's consumption information being associated with

their body weight, sex, age, ethnicity and other sociodemographic information. Individual

consumption estimates were weighted to be nationally representative. From these data single day and

3 day average consumption estimates were derived for the U.S. population and select population

subgroups. Three day average information is used in the DRES chronic exposure analyses.

The Agency acknowledges that the data from this survey are more than 20 years old.

However, at the time that the dietary assessment for alachlor was conducted, the data were the best

information available to the Agency. 
80

High End Chronic Dietary (Food Source) Risk 

The DRES chronic exposure analysis assumes tolerance level residues and one hundred

percent crop treated to calculate the Theoretical Maximum Residue Contribution (TMRC) for the

overall U.S. population and 22 population subgroups. Selected subgroups are reported in Table 17.

Table 17: Chronic Dietary Analysis (Food Only)

Subgroup Exposure

(mg/kg/day)

%Reference Dose

U.S. population 0.000756 8

Non-nursing Infants 

(<1 year)

0.003258 33

Children (1-6) 0.001744 17

Children (7-12) 0.001221 12

All other population subgroups were less than 10% of the RfD.

Refined Chronic Dietary (Food Source) Risk

The Dietary Exposure Assessment was refined using anticipated residues (ARs) and percent

crop treated (%CT) to give a refined, i.e. more realistic, dietary assessment. 

Calculation of Anticipated Residues

Existing FDA monitoring data were not used in calculating alachlor ARs because the data

were considered to be of limited usefulness for dietary risk assessment. FDA found no detectable

residues of alachlor, per se, in 53,600 samples, but the analyses did not include any of the alachlor

metabolites of concern. 

The anticipated residues, which are presented below in Table 18, were based on the average

residue found in field trials where alachlor was used at the maximum application rate. Additionally

a weighting factor was used for the percent of use at each application timing (i.e., preemergence vs.

postemergence). For example, 90% of corn is typically treated preemergence at 4 lb ai/A or less with

less than 10% treated postemergence (including sequential applications). Results of processing

studies were also used to adjust the residue levels found in the raw commodity to account for changes

in residue levels due to processing (both commercial and other types of processing). The typical

application rates and timing used for the anticipated residue analysis is provided in Table 18 for each

crop. 
81

Table 18: Anticipated Residues, Plant Commodities: Calculations and Summary

Average Residues from Alachlor Uses

Avg. Residue Proc. Factor Avg. Residue

Corn- 90% of use was preemergence at 4 lb ai/A, 10% of use was postemergence at 4 lb

ai/A or sequential applications (4+2 lb ai/A)

Corn grain 0.011 0.011 

Corn meal 0.9110.010 

Corn oil (refined) 0.1210.0014 

Corn starch 0.1920.0022 

Corn forage70.21 0.21 

Corn silage70.22 0.22 

Corn stover70.12 0.12 

Sweet Corn K+CWHR

 preemergence 4 lb ai/A 0.007 0.007 

Peanuts-35% of use was preemergence, 75% of use was cracking

Peanut hulls70.38 0.38 

Peanut nutmeat 0.15 0.15 

Peanut meal71.3710.21 

Peanut oil (refined) 0.0610.009 

Peanut butter 0.7030.11 

Peanuts, dry roasted 0.7530.11 

Peanuts, oil roasted 0.8330.12 

Sorghum preemergence 4 lb ai/A

Sorghum grain 0.02 0.02 

Sorghum forage70.29 0.29 

Sorghum fodder70.29 0.29 

Sorghum stover7

0.2 0.20 

Soybeans preemergence 4 lb ai/A

Soybean grain and 

soybean full fat and low fat flour

0.105 0.11 

Soybean grain dust76.0040.63 

Soybean hulls71.2240.13 

Soybean toasted meal (feed)70.8840.092 

Soybean defatted meal (food) 1.3040.137 

Soybean oil (refined) 0.1740.018 

Soybean protein concentrate 0.3240.034 
Table 18: Anticipated Residues, Plant Commodities: Calculations and Summary

Average Residues from Alachlor Uses

Avg. Residue Proc. Factor Avg. Residue

82

Soybean protein isolate 0.2140.022 

Soybean defatted flour 0.0905

Soybean forage71.36 1.36 

Soybean hay72.61 2.61 

Dry Beans preplant incorporated 3 lb ai/A

Dry beans 0.048 0.2060.010 

Dry lima beans 0.040 0.2060.008 

Bean forage70.340 0.34 

Bean vines7

0.396 0.40 

Bean hay70.866 0.87 

1

 MRID 00162939 

2

 MRID 40788201 

3

 MRID 40820601 

4

 MRID 00154239, 00154240, 40947101, 41862901 41916301 

5

 4/7 defatted meal + 3/7 protein concentrates and isolates

6

 MRID 40820701 

7

 Livestock feed only

In estimating anticipated residues for milk, poultry and eggs, anticipated residues as calculated

in Table 18 were used in estimating the dietary burden. (See Table 7 for example of calculation.)

Estimated dietary burdens based on these anticipated residues in livestock feeds for cattle, poultry,

and swine were determined to be 0.49, 0.20, and 0.27 ppm, respectively. The anticipated residues

in livestock commodities were then corrected for the expected recovery in each livestock tissue.

Anticipated residue estimates for livestock commodities are listed in Table 19.

Table 19: Anticipated Residues in Livestock Commodities.

Alachlor Feeding Study Results Estimated Residues 

Feeding

Level

(ppm)

Residue

 (ppb)

Dietary

Burden

 (ppm)

Residue

Measured

by Method

 (ppb)

% Residue

of Concern

Measured

by Method

Total Residue

of Concern

(ppb)

BEEF

muscle 4.20 1.20 0.53 0.15 38% 0.40 

fat 4.20 1.90 0.53 0.24 70% 0.34 
Table 19: Anticipated Residues in Livestock Commodities.

Alachlor Feeding Study Results Estimated Residues 

Feeding

Level

(ppm)

Residue

 (ppb)

Dietary

Burden

 (ppm)

Residue

Measured

by Method

 (ppb)

% Residue

of Concern

Measured

by Method

Total Residue

of Concern

(ppb)

83

liver 4.20 7.80 0.53 0.98 58% 1.70 

kidney 4.20 8.70 0.53 1.10 68% 1.61 

milk 4.20 1.50 0.69 0.25 40% 0.62 

POULTRY

muscle 12.00 1.00 0.09 0.01 34% 0.02 

fat 12.00 1.30 0.09 0.01 75% 0.01 

liver 4.00 2.10 0.09 0.05 51% 0.09 

eggs 4.00 6.90 0.09 0.16 60% 0.26 

SWINE

muscle 4.00 1.30 0.19 0.06 38% 0.16 

fat 4.00 2.60 0.19 0.12 70% 0.18 

liver 4.00 4.10 0.19 0.19 58% 0.34 

kidney 12.00 7.40 0.19 0.12 68% 0.17 

Since the dietary exposure assessment is based on field trial data, the anticipated residues are

likely to overestimate the dietary exposure because the application rates and timing assumed in the

dietary exposure analysis were at the highest rate on the label, which is not necessarily the typical rate

used by the applicator. Additionally, residues are likely to degrade from the time that samples are

obtained at the farm gate during transportation, processing and storage, prior to consumption. For

the livestock commodities, the following assumptions were used: (1) all alachlor metabolite residues

found in the livestock animal metabolism studies are residues of concern and (2) the percentage

recovery of the analytical method in livestock commodities is based on the percentage of metabolites

recovered in metabolism studies. Alachlor metabolites not identified specifically in the metabolism

studies may also respond to the analytical method, so the analytical recovery may be higher than

estimated. 

Percent Crop Treated Data

Percent crop treated (CT) information are from a three year period 1993 - 1995. The FQPA

amendments to Section 408(b)(2)(F) of the FFDCA require that if a tolerance relies on percent croptreated data, that the Agency make a determination as to the reliability of the data. The percent crop

treated estimates used by EPA are derived from Federal and private market survey data. Typically,

the Agency considers the range of percent crop treated data from a period of several years, and uses
84

the upper end of this range for estimating dietary exposure. In so doing, the Agency is reasonably

certain that exposure is not understated for any major population sub-group. Additionally, the DRES

(Dietary Risk Evaluation System) used in estimating chronic dietary risk uses regional consumption

information to estimate exposure for four population sub-groups that are based on geographical

regions of the United States. The Agency will provide for the periodic evaluation of these estimates

of percent crop treated, as long as the tolerances for alachlor remain in force. 

When a range of percent of crop treated estimates was supplied, the upper end (in bold) was

used. One hundred percent CT (default assumption) was used if no information was provided for a

crop. This data is now several years old. However, information available to the Agency indicates

that alachlor usage has fallen. Thus, these percent crop treated estimates can be considered as slight

over-estimates.

Table 20: Percent of Various U.S. Crops Treated Annually

with Alachlor

Commodities Percent Crop

Treated

Major Region or

State

Beans, Dry <10 Nationwide

Beans, Succulent 10 - 35 CA and ID

Corn, Sweet 30 - 35 Nationwide

Corn, Field 20 - 25 Nationwide

Peanuts <5 Southeast

Sorghum 10 - 15 Nationwide

Soybeans 5 - 10 Nationwide

Sunflowers <1 - 1 SD and NE

Refined dietary exposures and percent RfDs for selected subgroups are reported in Table 21.
85

Table 21: Chronic Refined Dietary Analysis (Food Only)

Subgroup Exposure

(mg/kg/day)

%Reference Dose

U.S. population 0.000011 0.1

Non-nursing Infants 

(<1 year)

0.000050 0.5

Children (1-6 years) 0.000029 0.3

Children (7-12 years) 0.000019 0.2

Male (20+ years) 0.000007 0.07

Female (13+ years), nursing 0.000010 0.1

All other population subgroups were less than 0.2% of the RfD. Thus, when using anticipated

residues and percent crop treated data, all population subgroups are well below the RfD for alachlor.

Chronic dietary risk from alachlor from all food uses for which tolerance reassessments have been

performed is not of concern.

Dietary Carcinogenic (Food Sources) Risk (MOE Approach)

 As stated previously, the Committee recommended using a Margin of Exposure (MOE)

approach for estimation of human risk, rather than the linear low dose approach. The NOELs, 0.5

mg/kg/day for nasal tumors and 14 mg/kg/day for stomach tumors, were used for estimating MOEs

for adult females and adult males using the chronic exposures in Table 21. It should be noted that

alachlor ESA is included in these estimates of exposure, since it is converted in the alachlor crop

residue methodology to DEA. Since alachlor ESA is unlikely to be carcinogenic in a 2-year bioassay

these residues should not be included in the carcinogenic assessment, but cannot be separated out.

Therefore, these exposure estimates are very slight over-estimates. 

Carcinogenic MOE = NOEL / exposure 

At this time the Agency is not making any recommendations on the level of MOEs to be

considered acceptable for dietary risk. However, given the magnitude of the calculated MOEs,

dietary cancer risk from all food uses for which tolerance reassessments have been performed is not

expected to be of concern. All MOEs in Table 22 have been rounded to two significant figures.
86

Table 22: Carcinogenic MOEs

Population Group Exposure MOE

Nasal Tumors (0.5 mg/kg/day)

Adult Male 0.000007 71,000

Adult Female 0.000010 50,000

Stomach Tumors (14 mg/kg/day)

Adult Male 0.000007 2,000,000

Adult Female 0.000010 1,400,000

b. Drinking Water 

Chronic Drinking Water Risk

Percent RfDs for consumption of drinking water containing residues of alachlor per se were

estimated using the RfD for alachlor of 0.01 mg/kg/day for adult males, adult females and child (1 -

6 years). There are no default assumptions for estimating risk for non-nursing infants (< 1 year),

although the same assumptions as used for a child (1 -6 years) could be used. Since, the chronic food

source risk for both of these sub-population groups was < 1%, the total dietary risk would be similar.

All RfDs were rounded to one significant figure. 

Table 23: Drinking Water Percent RfDs for Alachlor per se- Adult Male

STUDY Concentration

(ppb) 

Exposure

(mg/kg/day)

% RfD

MCL 2 0.0000571 0.6

Surface Water

USGS - Alachlor (reservoir) 0.22 0.0000062 0.06

ARP Data (1995-1996) (drinking water) 0.1 0.0000028 0.03

Ground Water

NAWWS 0.2 0.0000057 0.06

NAWWS 0.015 0.0000004 0.004
87

Table 24: Drinking Water Percent RfDs for Alachlor per se- Adult Female

STUDY Concentration

(ppb) 

Exposure

(mg/kg/day)

% RfD

MCL 2 0.0000666 0.7

Surface Water

USGS - Alachlor (reservoir) 0.22 0.0000073 0.07

ARP Data (1995-1996) (drinking water) 0.1 0.0000033 0.03

Ground Water

NAWWS 0.2 0.0000066 0.07

NAWWS 0.015 0.0000005 0.005

Table 25: Drinking Water Percent RfDs for Alachlor per se - Child (1 - 6 years)

STUDY Concentration

(ppb) 

Exposure

(mg/kg/day)

% RfD

MCL 2 0.0002 2

Surface Water

USGS - Alachlor (reservoir) 0.22 0.000022 0.2

ARP Data (1995-1996) (drinking water) 0.1 0.00001 0.1

Ground Water

NAWWS 0.2 0.00002 0.2

NAWWS 0.015 0.0000015 0.02

All % RfD values are well below 100%. Chronic dietary risk from alachlor from consumption

of water containing residues of alachlor per se is not of concern.

No RfD for alachlor ESA has been determined; the toxicological data base is incomplete.

Therefore, a default assumption would be to use the parent alachlor RfD for the metabolite. Using

the exposures estimated in Tables 6, 7, and 8 and the alachlor RfD of 0.01 mg/kg/day, percent RfDs

were estimated to be of 0.9%, 1%, and 3% for adult male, adult female and children (1-6 years),

respectively. Another assumption would be to calculate a value for use in a chronic dietary risk

assessment using the NOEL from the 91-day alachlor ESA drinking water study. Using the NOEL

of 157 mg/kg/day and an uncertainty factor of 1000 (to account for interspecies extrapolation,

intraspecies variability and lack of a complete database) a value of 0.16 mg/kg/day was calculated.

This gives percent RfDs of 0.05%, 0.06%, and 0.2% for adult male, adult female and children (1-6

years), respectively. Note that both of these approaches indicate little concern for consumption of

alachlor ESA in the drinking water.
88

Carcinogenic Drinking Water Risk

Carcinogenic MOEs were calculated for adult males and females only. Alachlor ESA is not

included in the MOEs since it was determined that alachlor ESA is unlikely to be carcinogenic in a

2-year bioassay. All MOEs were rounded to two significant figures.

Table 26: Drinking Water Carcinogenic MOEs - (Adult Male)

STUDY Concentration

(ppb) 

Exposure

(mg/kg/day)

MOE1 MOE2

MCL 2 0.0000571 8,800 250,000

Surface Water

USGS - Alachlor 0.22 0.0000062 45,000 2,300,000

ARP Data

(1995-1996)

0.1 0.0000028 180,000 6,400,000

Ground Water

NAWWS 0.2 0.0000057 88,000 2,500,000

NAWWS 

(99.5% population)

0.015 0.0000004 1,200,000 35,000,000

1 MOE for nasal tumors (0.5 mg/kg/day)

2 MOE for stomach tumors (14 mg/kg/day)

Table 27: Drinking Water Carcinogenic MOEs - (Adult Female)

STUDY Concentration

(ppb) 

Exposure

(mg/kg/day)

MOE1 MOE2

MCL 2 0.0000666 7,500 210,000

Surface Water

USGS - Alachlor 0.22 0.0000073 68,000 1,900,000

ARP Data 0.1 0.0000033 150,000 5,400,000

Ground Water

NAWWS 0.2 0.0000066 76,000 21,000,000

NAWWS

(99.5% population)

0.015 0.0000005 1,000,000 28,000,000

1 MOE for nasal tumors

2 MOE for stomach tumors
89

At this time the Agency is not making any recommendations on the level of MOEs to be

considered acceptable for dietary (drinking water) risk. However, given the magnitude of the

calculated MOEs, dietary (drinking water) cancer risk is not expected to be of concern.

c. Aggregate (Food and Water) 

Aggregate Chronic Dietary (Food Source and Drinking Water) Risk

This assessment combines the food residue exposure estimates with drinking water exposure

estimates to calculate an aggregate chronic exposure. Percent RfDs for aggregate chronic dietary risk

were calculated for adult males, adult females, and children (1 - 6 years). All RfDs were rounded to

one significant figure.

Adult Male - Alachlor

Using the refined adult male food source exposure from Table 21 and NAWWS (Midwest ground

water) exposure from Table 23:

Exposure = 0.000007 mg/kg/day +0.0000057 mg/kg/day = 0.0000127 mg/kg/day

% RfD = 0.0000127 / 0.01 (100)= 0.1 % 

Using the refined adult male food source exposure from Table 21 and USGS reservoir (Midwest

surface water) from Table 23:

Exposure = 0.000007 mg/kg/day + 0.0000062 mg/kg/day = 0.0000132 mg/kg/day

%RfD =0.0000132 / 0.01 (100) = 0.1 %

Using the refined adult male food source exposure from Table 21 and ARP (12 state area surface

water) from Table 23:

Exposure = 0.000007 mg/kg/day +0.0000028 mg/kg/day = 0.0000098 mg/kg/day

% RfD = 0.0000098 / 0.01 (100) = 0.1 %

Adult Male - Alachlor and Alachlor ESA

Using the refined adult male food source exposure from Table 21 and USGS reservoir (Midwest

surface water) exposure from Table 23: 

Exposure = 0.000007 mg/kg/day + 0.0000062 mg/kg/day + 0.0000857 mg/kg/day =

0.0000989 mg/kg/day
90

% RfD = 0.0000989 / 0.01 (100) = 1 %

Adult Female Alachlor

Using the refined adult female food source exposure from Table 21 and NAWWS (Midwest ground

water) exposure from Table 24:

Exposure = 0.000010 mg/kg/day + 0.0000066 mg/kg/day = 0.0000166 mg/kg/day

% RfD = 0.0000166 / 0.01 (100) = 0.2 %

Using the refined adult female food source exposure from Table 21 and USGS reservoir (Midwest

surface water) from Table 24:

Exposure = 0.000010 mg/kg/day + 0.0000073 mg/kg/day = 0.0000173 mg/kg/day

% RfD = 0.0000173 / 0.01 (100) = 0.1%

Using the refined adult female food source exposure from Table 21 and ARP (12 state area surface

water) from Table 24:

Exposure = 0.000010 mg/kg/day + 0.0000033 mg/kg/day = 0.0000133 mg/kg/day

% RfD = 0.0000133 / 0.01 = 0.1%

Adult Female - Alachlor and Alachlor ESA

Using the refined adult female food source exposure from Table 21 and USGS reservoir (Midwest

surface water) from Table 24: 

Exposure = 0.000010 mg/kg/day + 0.0000073 mg/kg/day +0.0001 mg/kg/day = 

0.0001173 mg/kg/day

% RfD = 0.0001173 / 0.01 (100) = 1 %

Child (1-6 years) - Alachlor

Using the refined child (1-6 years) food source exposure from Table 21 and NAWWS (Midwest

ground water) exposure from Table 24:

Exposure = 0.000029 mg/kg/day + 0.00002 mg/kg/day = 0.000049 mg/kg/day

% RfD = 0.000049 / 0.01 (100) = 0.5%
91

Using the refined child (1-6 years) food source exposure from Table 21 and USGS reservoir

(Midwest surface water) from Table 25:

Exposure = 0.000029 mg/kg/day + 0.000022 mg/kg/day = 0.000051 mg/kg/day

% RfD = 0.000051 / 0.01 (100) = 0.5 %

Using the refined child (1-6 years) food source exposure from Table 21 and ARP (12 state area

surface water) from Table 25:

Exposure = 0.000029 mg/kg/day + 0.00001 mg/kg/day = 0.000039 mg/kg/day

% RfD = 0.000039 / 0.01 (100) = 0.4 %

Child (1 - 6 years) - Alachlor and Alachlor ESA

Using the refined child (1-6 years) food source exposure from Table 21 and USGS reservoir

(Midwest surface water) from Table 25:

Exposure = 0.000029 mg/kg/day + 0.000022 mg/kg/day + 0.0003 mg/kg/day = 

0.000351 mg/kg/day

% RfD = 0.000351 / 0.01 (100) = 4 %

All % RfDs for aggregate chronic dietary risk are well below 100%. Chronic dietary risk from

alachlor from food containing residues of alachlor and from consumption of water containing residues

of alachlor per se and/or residues of alachlor ESA is not of concern.

Aggregate Carcinogenic Dietary (Food and Water) Risk (MOE Approach)

MOEs for aggregate carcinogenic dietary risk were calculated for adult males and females.

All MOEs were rounded to two significant figures. Per the recommendations of the Metabolism

Committee, alachlor ESA is not included in the carcinogenic assessment.

Adult Male

Using the refined adult male food source exposure from Table 21 and NAWWS (Midwest ground

water) exposure from Table 23:

Exposure = 0.000007 mg/kg/day +0.0000057 mg/kg/day = 0.0000127 mg/kg/day

MOE (nasal) = 0.5 / 0.0000127 = 39,000
92

MOE (stomach) = 14 / 0.0000127 = 1,100,000 

Using the refined adult male food source exposure from Table 21 and USGS reservoir (Midwest

surface water) from Table 23:

Exposure = 0.000007 mg/kg/day + 0.0000062 mg/kg/day = 0.0000132 mg/kg/day

MOE (nasal) = 0.5 / 0.0000132 = 38,000

MOE (stomach) = 14 / 0.0000132 = 1,100,000

Using the refined adult male food source exposure from Table 21 and ARP (12 state area surface

water) from Table 23:

Exposure = 0.000007 mg/kg/day +0.0000028 mg/kg/day = 0.0000098 mg/kg/day

MOE (nasal) = 0.5 / 0.0000098 = 51,000

MOE (stomach) = 14 / 0.0000098 = 1,400,000

Adult Female

Using the refined adult female food source exposure from Table 21 and NAWWS (Midwest ground

water) exposure from Table 24:

Exposure = 0.000010 mg/kg/day + 0.0000066 mg/kg/day = 0.0000166 mg/kg/day

MOE (nasal) = 0.5 / 0.0000166 = 30,000

MOE (stomach) = 14 / 0.0000166 = 840,000

Using the refined adult female food source exposure from Table 21 and USGS reservoir (Midwest

surface water) from Table 24:

Exposure = 0.000010 mg/kg/day + 0.0000073 mg/kg/day = 0.0000173 mg/kg/day

MOE (nasal) = 0.5 / 0.0000173 = 29,000

MOE (stomach) = 14 / 0.0000173 = 810,000

Using the refined adult female food source exposure from Table 21 and ARP (12 state area surface

water) from Table 24:
93

Exposure = 0.000010 mg/kg/day + 0.0000033 mg/kg/day = 0.0000133 mg/kg/day

MOE (nasal) = 0.5 / 0.0000133 = 38,000

MOE (stomach) = 14 / 0.0000133 = 1,100,000

At this time the Agency is not making any recommendations on the level of MOEs to be

considered acceptable for aggregate (food and water) dietary risk. However, given the magnitude

of the calculated MOEs (ranging from 29,000 to 1,400,000), aggregate carcinogenic dietary risk from

all food uses for which tolerance reassessments have been performed is not expected to be of concern.

Aggregate Carcinogenic Dietary (Food and Water) Risk (Q1

*

 Approach)

Aggregate carcinogenic dietary risk using the Q1

*

 approach were calculated for adult males

and females. All risks were rounded to two significant figures. Per the recommendations of the

Metabolism Committee, alachlor ESA is not included in the carcinogenic assessment.

Risk = ( Q1

*

 )(exposure)

Adult Male

Using the refined adult male food source exposure from Table 21 and NAWWS (Midwest ground

water) exposure from Table 23:

Exposure = 0.000007 mg/kg/day + 0.0000057 mg/kg/day = 0.0000127 mg/kg/day

Risk = [0.08 (mg/kg/day)-1 ][ 0.0000127 mg/kg/day] = 1.0 x 10-6

Using the refined adult male food source exposure from Table 21 and USGS reservoir (Midwest

surface water) from Table 23:

Exposure = 0.000007 mg/kg/day + 0.0000062 mg/kg/day = 0.0000132 mg/kg/day

Risk = [0.08 (mg/kg/day)-1 ][ 0.0000132 mg/kg/day] = 1.1 x 10-6

Using the refined adult male food source exposure from Table 21 and ARP (12 state area surface

water) from Table 23:

Exposure = 0.000007 mg/kg/day +0.0000028 mg/kg/day = 0.0000098 mg/kg/day

Risk = [0.08 (mg/kg/day)-1 ][ 0.0000098 mg/kg/day] = 7.8 x 10-7

Adult Female
94

Using the refined adult female food source exposure from Table 21 and NAWWS (Midwest ground

water) exposure from Table 24:

Exposure = 0.000010 mg/kg/day + 0.0000066 mg/kg/day = 0.0000166 mg/kg/day

Risk = [0.08 (mg/kg/day)-1 ][ 0.0000166 mg/kg/day] = 1.3 x 10-6

Using the refined adult female food source exposure from Table 21 and USGS reservoir (Midwest

surface water) from Table 24:

Exposure = 0.000010 mg/kg/day + 0.0000073 mg/kg/day = 0.0000173 mg/kg/day

Risk = [0.08 (mg/kg/day)-1 ][ 0.0000173 mg/kg/day] = 1.4 x 10-6

Using the refined adult female food source exposure from Table 21 and ARP (12 state area surface

water) from Table 24:

Exposure = 0.000010 mg/kg/day + 0.0000033 mg/kg/day = 0.0000133 mg/kg/day

Risk = [0.08 (mg/kg/day)-1 ][ 0.0000133 mg/kg/day] = 1.1 x 10-6

All carcinogenic risks estimated using the Q1

*

 are within the risk range considered by the

Agency to represent negligible risk.

d. Occupational 

Short Term Risk

For the short-term risk assessment, a NOEL of 150 mg/kg/day was used to calculate the

MOE. The Agency used a 60 kg body weight, the Agency's default female body weight since the

selected endpoint is from a developmental study. Since the NOEL is from an oral study, the dermal

absorption factor of 24% was used to estimate oral-equivalents for the dermal exposure.

Intermediate Term Risk

For the intermediate-term risk assessment, a NOEL of 50 mg/kg/day was used to calculate

the MOE. The Agency used a 70 kg body weight, the Agency's default adult body weight. Since the

NOEL is from a dermal study, use of the dermal absorption factor is not appropriate. 

Estimates of short-term and intermediate-term occupational risk to alachlor are summarized

in Tables 28 and 29. All MOEs have been rounded to 1 or 2 significant figures.
95

Table 28: Short-Term Risk from Alachlor

Exposure Scenario 

(Scenario #)

Crop/

Ratea

Baseline

Absorbed Total

Dose

(mg/kg/day)b,e

Baseline 

MOEc

PPE

Absorbed Doseb,f

(mg/kg/day)

PPE

MOEc

Eng. C

Absorbed

Doseb,g

(mg/kg/day)

Eng. C

MOEc

Biomonitoring

Internal Dose

(mg/kg/day) d

Biomonitoring 

MOEc

Mixer/Loader Exposure

Mixing/Loading Liquids for Aerial

Application and Chemigation (1a)

Corn 4.0 16.3 9 0.27 560 N/A N/A 0.01764 8500

Soybean 3.0 12.2 12 0.20 750 N/A N/A N/A N/A

Mixing/Loading Liquids for

Groundboom Application (1b)

Corn 4.0 3.7 41 0.061 2,500 N/A N/A 0.004032 37,000

Soybean 3.0 2.8 54 0.046 3,300 N/A N/A N/A N/A

Mixing/Loading Granulars for Drop

Type Tractor Drawn Spreader

Application (2)

Corn 4.0 0.019 7,900 N/A N/A N/A N/A 0.00002070 720,000

Soybean 3.0 0.014 11,000 N/A N/A N/A N/A N/A N/A

Mixing/Loading Dry Flowables for

Aerial Application (3a)

Corn 4.0 0.41 370 N/A N/A N/A N/A 0.0004424 34,000

Soybean 3.0 0.31 480 N/A N/A N/A N/A N/A N/A

Mixing/Loading Dry Flowables for

Groundboom Application (3b)

Corn 4.0 0.094 1,600 N/A N/A N/A N/A 0.0001024 150,000

Soybean 3.0 0.07 2,100 N/A N/A N/A N/A N/A

Applicator Exposure

Aerial Application of Liquids -

Fixed-Wing Aircraft - Enclosed

Cockpit (4)

Corn 4.0 See Eng.

Controls

See Eng.

Controls

See Eng.

Controls

See Eng.

Controls

0.030 5000 N/A N/A

Soybean 3.0 See Eng.

Controls

See Eng.

Controls

See Eng.

Controls

See Eng.

Controls

0.022 6800 N/A N/A

Aerial Application of Liquids -

Helicopter - Enclosed Cockpit (5)

Corn 4.0 See Eng.

Controls

See Eng.

Controls

See Eng.

Controls

See Eng.

Controls

0.012 13000 N/A N/A

Soybean 3.0 See Eng.

Controls

See Eng.

Controls

See Eng.

Controls

See Eng.

Controls

0.009 17000 N/A N/A

Groundboom Application of Liquids 

(6)

Corn 4.0 0.023 6,500 N/A N/A N/A N/A 0.004032 35,000

Soybean 3.0 0.017 8,800 N/A N/A N/A N/A N/A N/A

Granular Drop Type Tractor Drawn

Spreader Application (7)

Corn 4.0 0.014 11,000 N/A N/A N/A N/A 0.002454 61,000

Soybean 3.0 0.01 15,000 N/A N/A N/A N/A N/A N/A
Table 28: Short-Term Risk from Alachlor

Exposure Scenario 

(Scenario #)

Crop/

Ratea

Baseline

Absorbed Total

Dose

(mg/kg/day)b,e

Baseline 

MOEc

PPE

Absorbed Doseb,f

(mg/kg/day)

PPE

MOEc

Eng. C

Absorbed

Doseb,g

(mg/kg/day)

Eng. C

MOEc

Biomonitoring

Internal Dose

(mg/kg/day) d

Biomonitoring 

MOEc

96

Mixer/Loader/Applicator

Mixing/Loading and Application for

Dry Bulk Fertilizer (8)

See text

Flaggers

Flaggers for Aerial Applications (9) Corn 4.0 0.063 2,400 N/A N/A N/A N/A N/A N/A

Soybean 3.0 0.047 3200

PPE personal protective equipment 

Eng. C engineering controls 

a Rates are from Alachlor labels EPA Reg Nos. 524-344, 524-403, 524-418, 524-422 and 524-314.

b Absorbed Total Dose ((daily dermal exposure * dermal absorption rate 0.24) + (daily inhalation exposure)) / 60 kg.

c MOE = NOEL (150 mg/kg/day) / absorbed total dose.

d Biomonitoring (See Table 16) Estimated only for 4 lb ai.

e See Table 13 footnotes for explanation of calculations 

f See Table 14 footnotes for explanation of calculations and description of PPE

g See Table 15 footnotes for explanation of calculations and description of engineering controls 
97

 

 Table 29: Intermediate-Term Risk from Alachlor

Exposure Scenario 

(Scenario #)

Crop/

Ratea

Baseline Total

Doseb,e

(mg/kg/day)

Baseline

Total

Dermal

MOEc

PPE Daily

Total Doseb,f

(mg/kg/day)

PPE Total

MOEc

Eng. C Daily

Total Doseb,g

(mg/kg/day) 

Eng. C Total

MOEc

Biomonitoring

Internal Dose

(mg/kg/day) d

Biomonitoring

MOEc

Mixer/Loader Exposure

Mixing/Loading Liquids for Aerial

Application and Chemigation (1a)

Corn 4.0 58.0 0.9 0.54 93 0.18 280 0.01764 2800

Soybean 3.0 43.5 1 0.39 130 N/A N/A N/A N/A

Mixing/Loading Liquids for

Groundboom Application (1b)

Corn 4.0 13.3 4 0.2 250 N/A N/A 0.004032 12,000

Soybean 3.0 9.9 5 0.17 300 N/A N/A N/A N/A

Mixing/Loading Granulars for Drop

Type Tractor Drawn Application (2)

Corn 4.0 0.04 1,300 N/A N/A N/A N/A 0.0000207 2,400,000

Soybean 3.0 0.03 1,700 N/A N/A

Mixing/Loading Dry Flowables for

Aerial Application (3a)

Corn 4.0 1.42 35 0.82 61 No data No data 0.0004424 110,000

Soybean 3.0 1.05 47 0.61 82 N/A N/A

Mixing/Loading Dry Flowables for

Groundboom Application (3b)

Corn 4.0 0.32 160 N/A N/A N/A N/A 0.0001024 490,000

Soybean 3.0 0.24 210 N/A N/A

Applicator Exposure

Aerial Application of Liquids -

Fixed-Wing Aircraft - Enclosed

Cockpit (4)

Corn 4.0 See Engineering Controls See

Engineering

Controls

See

Engineering

Controls

0.10 500 N/A N/A

Soybean 3.0 0.08 630 N/A N/A

Aerial Application of Liquids -

Helicopter - Enclosed Cockpit (5)

Corn 4.0 See Engineering Controls See

Engineering

Controls

See

Engineering

Controls

0.042 1,200 N/A N/A

Soybean 3.0 0.031 1,600 N/A N/A

Groundboom Application of Liquids

(6)

Corn 4.0 0.072 690 N/A N/A N/A N/A 0.004032 12,000

Soybean 3.0 0.054 930 N/A N/A N/A N/A N/A N/A

Granular Drop Type Tractor Drawn

Spreader Application (7)

Corn 4.0 0.047 1,100 N/A N/A N/A N/A 0.002454 20,000

Soybean 3.0 0.036 1,400 N/A N/A
 Table 29: Intermediate-Term Risk from Alachlor

Exposure Scenario 

(Scenario #)

Crop/

Ratea

Baseline Total

Doseb,e

(mg/kg/day)

Baseline

Total

Dermal

MOEc

PPE Daily

Total Doseb,f

(mg/kg/day)

PPE Total

MOEc

Eng. C Daily

Total Doseb,g

(mg/kg/day) 

Eng. C Total

MOEc

Biomonitoring

Internal Dose

(mg/kg/day) d

Biomonitoring

MOEc

98

Mixer/Loader/Applicator

Mixing/Loading and Application for

Dry Bulk Fertilizer (8)

See text

Flaggers

Flaggers for Aerial Applications (9) Corn 4.0 0.206 240 N/A N/A N/A N/A N/A N/A

Soybean 3.0 0.154 330

N/A - not applicable

a From Alachlor labels EPA Reg Nos. 524-344, 524-403, 524-418, 524-422 and 524-314.

b Total dose = (daily dermal exposure) + (daily inhalation exposure) / 70 kg.

c MOE = NOEL (50 mg/kg/day) / total dose (mg/kg/day).

d Biomonitoring (See Table 16) Estimated only for 4 lb ai.

e See Table 13 footnotes for explanation of calculations 

f See Table 14 footnotes for explanation of calculations and description of PPE

g See Table 15 footnotes for explanation of calculations and description of engineering controls
99

Occupational Risk Characterization

Short-Term Exposure

Using the registrant-submitted biomonitoring data, all short-term MOEs are much greater than

100.

Using PHED data for estimating short-term risk the MOEs are more than 100 at baseline for

scenarios:

(2) mixing/loading granulars for drop type tractor drawn spreader application, 

(3a) mixing/loading dry flowables for aerial application, 

(3b) mixing/loading dry flowables for groundboom application, 

(6) liquid groundboom application, 

(7) granular drop type tractor drawn spreader application, and 

(9) flaggers

Using PHED data with additional PPE and the corresponding decreases in exposure, the

MOEs are more than 100 for short-term risk for scenarios: 

(1a) mixing/loading liquids for aerial application and chemigation, and 

(1b) mixing/loading liquids for groundboom application.

Using PHED data with engineering controls (no other data were available) the calculated

MOEs are more than 100 for short-term risk for scenarios: 

(4) liquid aerial application (fixed-wing), and 

(5) liquid aerial application (helicopter). 

Thus, it was possible to achieve MOEs greater than 100 for all scenarios for which data

existed in PHED.

Intermediate-Term Exposure 

Using the registrant-submitted biomonitoring data, all intermediate MOEs are much greater

than 100.

Using PHED for intermediate term risk the MOEs are more than 100 at baseline for risk for

scenarios: 

(2) mixing/loading granulars groundboom application, 

(3b) mixing/loading dry flowables for groundboom application, 

(6) liquid groundboom application, and 

(9) flaggers.

Using PHED with additional PPE and the corresponding decreases in exposure the MOEs

are more than 100 for intermediate-term risk for scenarios: 
100

(1a) mixing/loading liquids for aerial application (for rate of 3.0 lb ai/acre for soybeans), and 

(1b) mixing/loading liquids for groundboom application. 

Using PHED with engineering controls and the corresponding decreases in exposure the

MOEs are more than 100 for intermediate-term risk for scenarios: 

(1a) mixing/loading liquids for aerial application (for the rates of 4.0 lb ai/acre for corn), 

(4) aerial application of liquids (fixed-wing aircraft), and 

(5) aerial application of liquids (helicopter).

However, despite available PPE mitigation measures, it was not possible to achieve an MOE

of greater than 100 for scenario (3a) mixing/loading dry flowables for aerial application. There are

no engineering controls currently available for dry flowable formulations. Therefore, estimation of

exposure and resultant risk was not performed.

Dry Bulk Fertilizer Scenario

Using information provided by Monsanto, the Agency estimated MOEs for mixer/loaders

using a liquid alachlor product to impregnate dry bulk fertilizer, and for applicators applying the

treated fertilizer. This assessment was based on information provided by Monsanto in which the

processes involved in treating fertilizer with alachlor and applying the treated fertilizer were

described. (MRID No. 44492302) 

Dry bulk fertilizer impregnated with alachlor is typically prepared by local agricultural dealers,

and is then transported to the fields and applied. According to the information provided by Monsanto

there is a division of labor, in that most dealers, even small dealer operations, usually have different

individuals running the mixing equipment and applying the mix to fields. This is because of the

different skill requirements and to achieve better productivity. Thus, the Agency performed separate

assessments for mixer/loaders, and applicators. If an individual were to mix/load/apply, then the risk

would increase correspondingly.

There is also a Granu-Blend system, which is a system for applying granular alachlor at the

same time as application of the fertilizer, and is thus similar to the mixer/loader and applicator

scenarios for granular materials discussed in other sections of this alachlor RED chapter.

Mixer/Loaders

The Agency's preliminary review of exposure to workers impregnating dry bulk fertilizer with

liquid formulations of alachlor expressed concern over an absence of data and the potential for

significant exposure. 

According to the labels the blending must be performed by commercial fertilizer or chemical

dealerships properly equipped for the procedure. The amount of fertilizer and alachlor handled

depends on the number of acres to be treated. According to alachlor labels, from 200 to 450 lbs. of
101

impregnated fertilizer may be applied per acre, preplant to corn, grain sorghum, and soybeans. The

maximum single application rate for alachlor is 4 lbs ai/acre per new labels approved by the Agency

on June 30, 1998. 

According to the University of Illinois Extension Service: The herbicide is metered from a

mini-bulk tank (several hundred gallons) to a mixing drum via a closed system. The herbicide is

sprayed onto the fertilizer, which is stirred by an auger that lifts it to the top of the drum. After

impregnation, the treated fertilizer is gravity-fed through a hopper onto a conveyor belt leading to

an auger truck, which carries it to the field. At the field, the auger truck feeds the treated fertilizer

onto the applicator vehicle, which dispenses it from either a rotary spinner or a boom with numerous

outlets. The transfer of the treated fertilizer in each instance is nearly dust-free, as it has been

moistened by the herbicide. Because all processes are mechanized, there is minimal contact of either

the mixer at the treatment site or the loader at the transfer sites. Applicator exposure is minimized

by the use of a closed cab.

The information supplied by Monsanto indicates that impregnation of fertilizer in a mixing

tower is typically a closed system operation. Monsanto provided a diagram of a mixing/loading tower

which specifies that up to 120 tons of fertilizer can be processed per hour. If the tower were assumed

to process for 8 hours per day, then this would be 960 tons of fertilizer processed per 8 hour day.

At 3 to 4 lbs active ingredient per 200 lbs fertilizer, each ton of fertilizer would require 30 to 40 lbs

of alachlor active ingredient. Thus, the total amount of active ingredient for 960 tons at the 4 lb ai

rate is (960)(40) = 38400 lbs, and at the 3 lb ai rate is (960)(30) = 28800 lbs. The new information

submitted by Monsanto, and confirmed by the Agency, specified that the typical or average fertilizer

use rate is approximately 400 lbs/acre. At 4 lbs active ingredient per 400 lbs fertilizer, each ton of

fertilizer would require 20 lbs of alachlor active ingredient. Thus, the total amount (based on 400 lbs

fertilizer per acre) for 4 lbs ai handled is (960)(20) = 19,200 lbs.

Using the above information, the Agency has estimated risk for mixers/loaders impregnating

the dry bulk fertilizer assuming use of engineering controls (metered delivery from a mini-bulk tank).

Only the dermal values will be used in this assessment, since technical alachlor is classified as toxicity

category III, and for liquids, the unit inhalation exposure value is insignificant (differing by several

orders of magnitude) when compared to the unit dermal exposure value.

Daily exposure (mg/day) is estimated using the following equation:

unit exposure (mg/lb ai) x lbs ai handled per day 

Daily dose (mg/kg/day) is calculated by dividing the daily exposure (mg/day) by the body

weight (bw) of the worker. For the short-term scenario, the Agency used a 60 kg body weight, the

Agency’s default adult female body weight since the selected endpoint is from a developmental study.

Since the selected endpoint is from an oral study, the exposure must be adjusted to account for

dermal exposure. The dermal absorption factor is 24 percent (0.24). 
102

Thus, for the short-term scenario, absorbed daily dose = daily exposure (mg/day) / 60 kg x

0.24.

For the intermediate-term scenario, the Agency used a 70 kg body weight, the Agency’s

default adult body weight. Since the NOEL is from a dermal toxicity study, the dermal exposure will

not need to be adjusted by the dermal absorption factor. 

Thus, for the intermediate-term scenario, daily dose = daily exposure (mg/day) / 70 kg. 

Risk, in terms of margins of exposure (MOE), is calculated by using the following equation:

NOEL (mg/kg/day) / daily dose (mg/kg/day) = MOE.

All MOEs are rounded to one or two significant digits. For the short-term scenario, the

NOEL is 150 mg/kg/day. For the intermediate-term scenario, the NOEL is 50 mg/kg/day. Generally,

the Agency has no concerns for an MOE greater than or equal to 100 for non-cancer effects when

the NOEL used in estimating the MOE is from an animal study. 

The PHED V1.1 unit dermal exposure for a closed mixing/loading mechanical transfer system

(single layer clothing - with gloves) is 0.009 mg/lbs ai - high confidence.

Table 30: Short-Term with Engineering Controls (Closed Transfer System)

Unit Exposure

(mg/lbs ai)

Application Rate

(lbs ai/day)

Daily Exposure

(mg/day)

Daily Dose

(mg/kg/day)

MOE

0.009 38400 346 1.38 110

0.009 28800 259 1.04 140

0.009 19200 173 0.69 220

Table 31: Intermediate-Term with Engineering Controls (Closed Transfer System)

Unit Exposure

(mg/lbs ai)

Application Rate

(lbs ai/day)

Daily Exposure

(mg/day)

Daily Dose

(mg/kg/day)

MOE

0.009 38400 346 4.9 10

0.009 28800 259 3.7 14

0.009 19200 173 2.5 20

The Agency made assumptions in performing this assessment and acknowledges that many

of the assumptions were deliberately intended toward performing an upper-end assessment. One of

the most conservative of these assumptions was that the mixing tower would run at full capacity for
103

8 hours a day, thus generating 960 tons of alachlor impregnated fertilizer. It could require 32 to 96

truckloads per day (assuming 10 to 30 tons of fertilizer per truck) to spread the towers output. The

impregnated fertilizer market is likely to be a custom operation, in that (1) the blending occurs on an

as needed/as ordered basis, and (2) only the amount ordered is prepared.

All intermediate-term MOEs are less than 100; however, the Agency acknowledges that the

estimation of these MOEs did contain the conservative estimate of the mixing tower working 8 hours

per day. The short-term MOEs are greater than 100 considering mitigation with a closed transfer

system. Only the dermal component of the exposure - no inhalation exposure component - was

considered. 

The Agency also has concerns that the data in PHED may not adequately represent this

scenario. This is not a typical usage under agricultural field conditions. The amount of alachlor

necessary to impregnate the tons of fertilizer that can be processed in a day is far too large to be

handled by opening individual bottles or containers (as data collected for PHED), and probably

involves transfer from large containers such as tanker trucks or railroad tank cars. 

Extrapolating a unit exposure in the range of 19200 to 38400 lb ai/day from the available data

in PHED is likely to result in an over-estimate. The Agency does not have any bulk transfer/loading

data. This type of exposure data may be necessary for refining this assessment, and a possible option

for Monsanto would be to supply data per GLN 875.2400 (dermal exposure) and GLN 875.2500

(inhalation exposure) for mixer/loaders. 

Applicators - Baseline - Open Cab

The Agency has no data for spreader trucks applying treated fertilizer, and therefore selected

from PHED “solid broadcast spreader application - open cab" as a suitable surrogate. The dermal unit

exposure value (baseline - single layer clothing, no gloves, open cab) for a granular drop-type

spreader applicator is 0.01 mg/lb ai, and the inhalation unit exposure value (baseline - open cab) is

0.0012 mg/lbs ai (PHED V1.1, low confidence dermal and inhalation). Inhalation and dermal unit

exposures will be combined for the applicator scenario since the values are within two orders of

magnitude.

MOEs for both the short-term and intermediate-term scenarios have been estimated.

However, the Agency believes that the intermediate-term scenario is the most appropriate scenario

for estimating risk, since available information indicates that for pre-plant herbicide and fertilizer

applications that a “window” of approximately 28 days is available once the weather and field

conditions are right and the equipment can enter the fields.

For the short-term scenario, the total daily absorbed exposure (mg/day) is estimated using the

following equation:
104

[dermal unit exposure (mg/lb ai) x application rate (lbs ai/acre) x number of acres treated x

dermal absorption factor] + [inhalation unit exposure (mg/lb ai) x application rate (lbs

ai/acre) x number of acres treated] 

Given:

dermal unit exposure = 0.01 mg/lbs ai,

inhalation unit exposure = 0.0012 mg/lbs ai,

maximum application rate = 4 lbs ai per acre,

max number of acres treated = 800

typical number of acres treated = 500

dermal absorption factor = 0.24

Therefore:

Max total daily absorbed exposure = (0.01)(4)(800)(0.24) + (0.0012)(4)(800) 

= 11.52 mg/day.

Typical total daily absorbed exposure = (0.01)(4)(500)(.24) + (0.0012)(4)(500)

= 7.2 mg/day

Total daily absorbed dose (mg/kg/day) is calculated by dividing the total daily absorbed

exposure (mg/day) by 60 kg, the Agency’s default adult female body weight since the NOEL used

in estimating short-term risk is from a developmental study.

Max total daily dose = 11.52 mg/day / 60 kg = 0.192 mg/kg/day

Typical total daily dose = 7.2 mg/day / 60 kg = 0.12 mg/kg/day

Risk is estimated by using the following equation:

MOE = NOEL (mg/kg/day) / max total daily dose (mg/kg/day) = 150 / 0.192 = 780

MOE = NOEL (mg/kg/day) / typical total daily dose (mg/kg/day) = 150 / 0.12 = 1300

For the short-term scenario, the MOE for applicators applying fertilizer impregnated with

alachlor at the maximum application rate of 4 lbs ai to 800 acres per day is 780, and to 500 acres per

day is 1300. If lower application rates such as 3 lb ai/acre were to be used in the calculation, the

MOEs would be even higher. 

For the intermediate-term scenario, the total daily exposure (mg/day) is calculated using the

following equation:
105

[dermal unit exposure (mg/lb ai) x application rate (lbs ai/acre) x number of acres treated] +

[inhalation unit exposure (mg/lb ai) x application rate (lbs ai/acre) x number of acres treated]

Given:

dermal unit exposure = 0.01 mg/lbs ai,

inhalation unit exposure = 0.0012 mg/lbs ai,

maximum application rate = 4 lbs ai per acre,

max number of acres treated = 800

typical number of acres treated = 500

Therefore:

Max total daily exposure = (0.01)(4)(800) + (0.0012)(4)(800) = 35.84 mg/day.

Typical total daily exposure = (0.01)(4)(500) + (0.0012)(4)(500) = 22.4 mg/day

Total daily dose (mg/kg/day) is calculated by dividing the daily exposure (mg/day) by 70 kg, the

Agency’s default male body weight. 

Max total daily dose = 35.84 (mg/day) / 70 kg = 0.512 mg/kg/day

Typical total daily dose = 22.4 (mg/day) / 70 kg = 0.32 mg/kg/day

Risk is estimated by using the following equation:

MOE = NOEL (mg/kg/day) / max total daily dose (mg/kg/day) = 50 / 0.512 = 98

MOE = NOEL (mg/kg/day) / typical total daily dose (mg/kg/day) = 50 / 0.32 = 160

For the intermediate-term scenario, the MOE for applicators applying fertilizer impregnated

with alachlor equals 98 at the 4 lbs ai rate for 800 acres and 160 at the 4 lbs ai rate for 500 acres. 

The Agency made assumptions in performing this risk assessment and acknowledges that

many of the assumptions were deliberately used with the intent of performing an upper-end risk

assessment. Additionally, the Agency had only low confidence data due to the number of replicates

(5) in PHED. 

Applicators - Use of Engineering Controls

The Agency has no data for spreader trucks applying treated fertilizer, and therefore selected

from PHED “solid broadcast spreader application - closed cab" as a suitable surrogate. The dermal

unit exposure (closed cab) is 0.002 mg/lb ai, and the inhalation unit exposure (closed cab) is 0.00022
106

mg/lbs ai (PHED V1.1, low confidence dermal; high confidence hands and inhalation; no PFs

were used). Inhalation and dermal unit exposures will be combined for the applicator scenario since

the exposures are within two orders of magnitude.

MOEs for both the short-term and intermediate-term scenarios have been estimated. For the

short-term scenario, the total daily absorbed exposure (mg/day) is estimated using the following

equation:

[dermal unit exposure (mg/lb ai) x application rate (lbs ai/acre) x number of acres treated x

dermal absorption factor] + [inhalation unit exposure (mg/lb ai) x application rate (lbs

ai/acre) x number of acres treated] 

Given:

dermal unit exposure = 0.002 mg/lbs ai,

inhalation unit exposure = 0.00022 mg/lbs ai,

maximum application rate = 4 lbs ai per acre,

max number of acres treated = 800

typical number of acres treated = 500

dermal absorption factor = 0.24

Therefore:

Max total daily absorbed exposure = (0.002)(4)(800)(.24) + (0.00022)(4)(800) 

` = 2.24 mg/day.

Typical total daily absorbed exposure = (0.002)(4)(500)(.24) + (0.00022)(4)(500)

= 1.4 mg/day

Total daily absorbed dose (mg/kg/day) is calculated by dividing the total daily absorbed exposure

(mg/day) by 60 kg, the Agency’s default adult female body weight since the NOEL is from a

developmental study. 

Max total daily dose = 2.24 (mg/day) / 60 kg = 0.037 mg/kg/day

Typical total daily dose = 1.4 (mg/day) / 60 kg = 0.0233 mg/kg/day

Risk is estimated by using the following equation:

MOE = NOEL (mg/kg/day) / max total daily dose (mg/kg/day) = 150 / 0.037 = 4000

MOE = NOEL (mg/kg/day) / typical total daily dose (mg/kg/day)

= 150 / 0.0233 = 6400
107

For the short-term scenario, the MOE for applicators applying fertilizer impregnated with

alachlor at the maximum application rate of 4 lbs ai to 800 acres per day is 4000, and to 500 acres

is 6400. If lower application rates such as 3 lbs ai were to be used in the calculation, the MOEs

would be even higher. 

For the intermediate-term scenario, the total daily exposure (mg/day) is calculated using the

following equation:

[dermal unit exposure (mg/lb ai) x application rate (lbs ai/acre) x number of acres treated] +

[inhalation unit exposure (mg/lb ai) x application rate (lbs ai/acre) x number of acres treated]

Given:

dermal unit exposure = 0.002 mg/lbs ai,

inhalation unit exposure = 0.00022 mg/lbs ai,

maximum application rate = 4 lbs ai per acre,

max number of acres treated = 800

typical number of acres treated = 500

Therefore:

Max total daily exposure = (0.002)(4)(800) + (0.00022)(4)(800) = 7.1 mg/day.

Typical total daily exposure = (0.002)(4)(500) + (0.00022)(4)(500) = 4.44 mg/day

Total daily dose (mg/kg/day) is calculated by dividing the daily exposure (mg/day) by 70 kg, the

Agency's default male body weight. 

Max total daily dose = 7.1 (mg/day) / 70 kg = 0.101 mg/kg/day

Typical total daily dose = 4.44 (mg/day) / 70 kg = 0.063 mg/kg/day

Risk is estimated by using the following equation:

MOE = NOEL (mg/kg/day) / max total daily dose (mg/kg/day) = 50 / 0.101 = 490

MOE = NOEL (mg/kg/day) / typical total daily dose (mg/kg/day) = 50 / 0.063 = 790

For the intermediate-term scenario, the MOE for applicators applying fertilizer impregnated

with alachlor using a closed cab, at the 4 lbs ai rate to 800 acres is 490, and to 500 acres is 790.
108

With one exception (a MOE of 98), all MOEs, both short-term and intermediate-term, are

greater than 100. Generally, the Agency has no concerns for an MOE greater than or equal to 100,

for non-cancer effects when the NOEL used in estimating the MOE is from an animal study.

Additional Occupational Exposure Studies

Handler Studies

Optimally, worker exposure assessments are based on adequate data of acceptable quality.

Handler exposure studies are sometimes required for reregistration in situations in which no data or

no acceptable data exist. In this case exposure data are necessary to assess exposure to alachlor

resulting from the process of impregnating dry bulk fertilizer. While the Agency has used PHED data

in its assessment, the PHED data used are not directly related to this type of process. It appears that

this is a closed system; however, exposure may be significant based on the large volumes of alachlor

involved. PHED does not contain any data for transferring from mini-bulk containers. Therefore,

additional confirmatory data are required. The confirmatory data should address the dry bulk

fertilizer impregnation process, with alachlor in mini-bulk containers. This data should address both

dermal and inhalation exposure at both outdoor and indoor (at least partially enclosed) sites.

Post-Application Studies 

The Agency believes that, based on the current uses of alachlor, post-application exposure

will be low and therefore is not requiring post-application exposure studies at this time.

e. FQPA Considerations 

Aggregate Risk

In examining aggregate risk, FQPA directs EPA to take into account the available information

concerning exposures from the pesticide residue in food and all other exposures for which there is

reliable information. These other sources of exposure can include pesticides residues in drinking

water, pesticide uses in and around the home, and pesticide uses in non-residential settings, such as

schools or parks. 

Alachlor is used on food crops. Alachlor as well as its metabolites have been detected in both

ground and surface water. Therefore, specific consideration of potential risks to infants and children,

as well as aggregate exposures, is warranted.

Alachlor is a restricted use chemical. The Agency has not identified any alachlor products that

are intended for home use, or uses in/around schools, parks, or other public areas. Therefore, a

residential exposure and risk assessment was not required. For alachlor there is no residential

component to be added to the dietary (food and water) assessment.
109

Acute Aggregate Risk

Based on the available toxicity database, an acute dietary risk assessment was not required.

Chronic Aggregate Risk

Since alachlor has no residential uses to aggregate with the dietary assessment, the chronic

aggregate risk assessment is the same as the dietary (food and water)assessment. As previously

discussed in this document, the percent RfDs were calculated for adult males, adult females, and

children (1 - 6 years) using the food exposure estimated by DRES, and one source of drinking water.

All percent RfDs were rounded to one significant figure.

Table 32: Summary of Alachlor Aggregate Risk

Source of Drinking Water % RfD

Adult Male

NAWWS (Midwest groundwater) 0.1

USGS reservoir (Midwest surface water) 0.1

ARP 12 state area surface water 0.08

Adult Female

NAWWS (Midwest groundwater) 0.1

USGS reservoir (Midwest surface water) 0.1

ARP 12 state area surface water 0.1

Child (1 - 6 years)

NAWWS (Midwest groundwater) 0.5

USGS reservoir (Midwest surface water) 0.5

ARP 12 state area surface water 0.4

There are some data (USGS reservoir Midwest surface water) available on detections of the

alachlor ESA degradate. Using these data, aggregate risk can be estimated for consumption of water

containing both parent alachlor and alachlor ESA.
110

Table 33: Summary of Alachlor and Alachlor ESA Aggregate Risk

Population Group % RfD

Adult Male 1%

Adult Female 1%

Child (1 - 6 years) 4%

All % RfD values are well below 100%. Aggregate chronic dietary risk from all food uses

for which tolerance reassessments have been performed is not expected to be of concern.

Carcinogenic (MOE Approach) Aggregate Risk

Since alachlor has no residential uses to aggregate with the dietary assessment, the

carcinogenic aggregate risk assessment is the same as the carcinogenic (food and water) dietary

assessment. As previously discussed in this document, the carcinogenic MOEs were calculated for

adult males and adult females, using the food exposure estimated by DRES, and one source of

drinking water. All cancer MOEs were rounded to two significant figures.

Table 34: Summary of Alachlor Aggregate Carcinogenic (MOE Approach) Risk

Source of Drinking Water MOE 

Nasal Tumors

MOE 

Stomach Tumors

Adult Male

NAWWS (Midwest

groundwater)

39,000 1,100,000

USGS reservoir (Midwest

surface water)

38,000 1,100,000

ARP 12 state area surface

water

51,000 1,400,000

Adult Female 

NAWWS (Midwest

groundwater)

30,000 840,000

USGS reservoir (Midwest

surface water)

29,000 810,000

ARP 12 state area surface

water

38,000 1,100,000
111

At this time the Agency is not making any recommendations on the level of MOEs to be

considered acceptable for the carcinogenic MOE approach aggregate risk. However, given the

magnitude of the calculated MOEs, aggregate carcinogenic risk from all food uses for which

tolerance reassessments have been performed is not expected to be of concern.

Carcinogenic (Q1

*

 Approach) Aggregate Risk

Since alachlor has no residential uses to aggregate with the dietary assessment, the

carcinogenic aggregate risk assessment is the same as the carcinogenic (food and water) dietary

assessment. As previously discussed in this document, the carcinogenic risks were calculated for

adult males and adult females, using the food exposure estimated by DRES, and one source of

drinking water. All risk estimates were rounded to two significant figures.

Table 35: Summary of Alachlor Aggregate Carcinogenic (Q1

*

 Approach) Risk

Source of Drinking Water Risk

Adult Male

NAWWS (Midwest groundwater) 1.0 x 10-6

USGS reservoir (Midwest surface water) 1.1 x 10-6

ARP 12 state area surface water 7.8 x 10-7

Adult Female 

NAWWS (Midwest groundwater) 1.3 x 10-6

USGS reservoir (Midwest surface water) 1.4 x 10-6

ARP 12 state area surface water 1.1 x 10-6

All carcinogenic risks estimated using the Q1

*

 are within the risk range considered by the

Agency to represent negligible risk.

Cumulative Effects

The Food Quality Protection Act of 1996 (FQPA) amended the Federal Food, Drug, and

Cosmetic Act (FFDCA) by setting a new safety standard for the establishment of tolerances. Section

408(b)(2)(D)(v) of the FFDCA requires that, when considering whether to establish, modify, or

revoke a tolerance, the Agency consider "available information" concerning the cumulative effects

of a particular pesticide's residues and "other substances that have a common mechanism of toxicity."

The Agency believes that "available information" in this context might include not only toxicity,

chemistry, and exposure data, but also scientific policies and methodologies for understanding

common mechanisms of toxicity and conducting cumulative risk assessments. For most pesticides,
112

although the Agency has some information in its files that may turn out to be helpful in eventually

determining whether a pesticide shares a common mechanism of toxicity with any other substances,

EPA does not at this time have the methodologies to resolve the complex scientific issues concerning

common mechanism of toxicity in a meaningful way. EPA has begun a pilot process to study this

issue further through the examination of particular classes of pesticides. The Agency hopes that the

results of this pilot process will increase the Agency's scientific understanding of this question such

that EPA will be able to develop and apply scientific principles for better determining which chemicals

have a common mechanism of toxicity and evaluating the cumulative effects of such chemicals. The

Agency anticipates, however, that even as its understanding of the science of common mechanisms

increases, decisions on specific classes of chemicals will be heavily dependent on chemical specific

data, much of which may not be presently available.

At present there is no methodology for applying the information in the Agency’s files

concerning common mechanism issues for most risk assessments. But, there are pesticides for which

the common mechanism issues can be resolved. For example, pesticides that are toxicologically

dissimilar to existing chemical substances (in which case the Agency can conclude that it is unlikely

that a pesticide shares a common mechanism of activity with other substances) and pesticides that

produce a common toxic metabolite (in which case common mechanism of activity will be assumed).

Due to the structural similarities with acetochlor, metolachlor, butachlor, and propachlor,

alachlor may fall into the second category. However, at this time the Agency has not yet made a final

decision concerning a possible common mechanism of toxicity for these five chemicals to

scientifically apply that information to the tolerance decision. The process has begun, but is not yet

completed. Therefore, for the purposes of this decision document, the tolerance decision will be

reached based upon the best available and useful information for alachlor only. The risk assessment

has been performed for alachlor only assuming that no common mechanism of toxicity exists.

However, these decisions will be reexamined after methodologies and procedures for integrating

information concerning common mechanism of toxicity into risk assessments are developed by the

Agency. 

Monsanto must submit, upon EPA's request and according to a schedule determined by the

Agency, such information as the Agency directs to be submitted in order to evaluate issues related

to whether alachlor shares a common mechanism of toxicity with any other substance and, if so,

whether any tolerances for alachlor need to be modified or revoked.

c. Environmental Assessment

1. Use Characterization

Alachlor is a herbicide registered for use on the following crops: succulent and dry beans;

field, pop, and sweet corn; peanuts; grain sorghum; and soybeans. 
113

Use in Corn and Soybean Areas

Corn is grown in almost every state in the continental U.S. Major corn-growing areas include

the Midwest and Great Plains states (from Ohio west to Nebraska and from southern

Minnesota/Wisconsin south to Illinois/Missouri), the Mississippi River Valley, and the East Coast

(from southeastern Pennsylvania to North Carolina) (USDA National Agricultural Statistics Service,

1996 Harvested Acres by County). These regions include such wildlife-rich areas as the Prairie

Pothole region, Sandhills Lake region of Nebraska, and coastal/estuarine regions of the Delmarva

peninsula and North Carolina. Many of these areas are used by waterfowl and shorebirds as breeding,

feeding, and migratory resting grounds. In addition, corn may be grown in the vicinity of freshwater

and estuarine/marine aquatic habitats. This can lead to exposure of aquatic resources from the offsite movement of chemicals applied to cornfields near such habitats. 

The corn-growing region includes localized areas which have a high potential vulnerability

for contamination of shallow ground water with pesticides (Kellog et al., 1992). Such vulnerable

areas include the eastern coastal plain from southern Georgia to New Jersey, eastern Nebraska, and

southern portions of the Great Lakes region. While the majority of corn-growing areas are dominated

by soils which have a moderate runoff potential and moderate infiltration and permeability (also

referred to as Hydrologic Group B soils), localized regions are more susceptible to runoff (Kellog et

al., 1992). Areas with significant percentages of soils with moderately high to high runoff potential

(Group C and D soils) include the Gulf Coast region of Texas, the lower Mississippi River Valley,

the Missouri River Valley in South Dakota, the extreme eastern coastal plain of Georgia, South

Carolina, and North Carolina, and portions of the Ohio River Valley. These soils are more prone to

runoff because of slow permeability (low saturated hydraulic conductivities) and/or a relatively

shallow water table.

Use in Sorghum Areas

Major sorghum-growing areas in the U.S. are the central and southern Great Plains (from

Nebraska south to Texas and from eastern Colorado to Missouri) and the Mississippi River Valley

from southern Illinois to Louisiana (USDA National Agricultural Statistics Service, 1996 Harvested

Acres by County). The number of acres planted to sorghum appears to be increasing in the coastal

plains of the Carolinas and Georgia. While the geographic extent of the sorghum area is less than that

of corn, it does include significant areas of wildlife habitat. It may also be found in the vicinity of

estuarine/marine habitats, especially along the Gulf Coast region of Texas. Potential exposure of

aquatic resources may occur from the off-site movement of chemicals applied to sorghum fields near

such habitats. 

Sorghum is more tolerant of dry conditions than corn and is typically grown in warmer

climates which have a lower rainfall than the corn region. Overall, the major sorghum areas also have

a lower potential vulnerability for contamination of shallow ground water, except in the southeastern

U.S., where the acreage of sorghum is increasing (Kellog et al. 1992). Large areas of Texas and the

Mississippi River Valley are dominated by the high runoff potential Hydrologic Group C and D soils.
114

N

CH

2

H C

3

CH

2

CH

3

CH

2

O

H C

3

C

O

CH

2

Cl

HN

CH

2

H C

3

CH

3

C

O

C

CH

2

O

HO

In such areas, the adjacent aquatic habitats may be vulnerable to off-site movement of chemicals from

runoff.

Use on peanuts areas

Peanuts are grown primarily in the southern Coastal Plain, from Virginia to Alabama and in

the plains of central Texas and Oklahoma (USDA National Agricultural Statistics Service, 1996

Harvested Acres by County). The Coastal Plain region includes significant areas used by waterfowl

and shorebirds as breeding, feeding, and migratory resting grounds. Peanut-growing areas may occur

in the vicinity of freshwater and estuarine/marine aquatic habitats. The Coastal Plain includes a large

percentage of areas with a high potential vulnerability for contamination of shallow ground water with

pesticides (Kellog et al., 1992). 

Figure B: Alachlor and Its Degradates

The structures of alachlor and four of its degradates are illustrated in Figure B:

Nomenclature Chemical Structure

Alachlor

2-Chloro-2',6'-diethyl-Nmethoxymethylacetanilide 

Alachlor - DM-Oxanilic Acid

2',6'-Diethyloxanilic acid

(Compound III)
115

N

CH2

H C3

CH2

CH3

CH2

O

H C3C

O

CH2

S

CH2

O

C

OH

O

N

CH

2

H C

3

CH

2

CH

3

CH

2

O

H C

3

C

O

C

OH

O

N

CH

2

H C

3

CH

2

CH

3

C

O

CH

2

S

OH

O

O

CH

2

O

H C

3

Alachlor Sulfinylacetic Acid

(N-Methoxymethyl-N-(2,6-diethylphenyl)-

2-amino-2-oxoethyl)-sulfinylacetic acid 

(Compound VIII)

Alachlor Oxanilic Acid

2',6'-Diethyl-N-methoxymethyloxanilic acid

(Compound X)

Alachlor Sulfonic Acid

2',6'-Diethyl-N-methoxymethyl-2-

sulfoacetanilide

(Compound XI)

2. Ecological Toxicity Data

Ecological effects data are used by the Agency to determine the toxicological hazards of

pesticides to various terrestrial and aquatic nontarget organisms. These tests can include acute and

chronic scenarios. These data are then integrated with the environmental fate and exposure data

when the Agency performs a risk characterization.

The following studies provide the basis for the Ecological Effects Hazard Assessment.
116

a. Terrestrial Animals

To evaluate the toxicity of a pesticide to birds, the following tests are required using technical

grade material: 

C An avian single-dose oral (LD50) study on one species, preferably mallard or bobwhite

quail; 

C A subacute dietary (LC50) study using one waterfowl species, preferably the mallard

duck;

C A subacute dietary (LC50) study using one upland game species, preferably bobwhite

quail or ring-necked pheasant.

Tests on wild mammals may be required, depending on intended use pattern, environmental

fate characteristics, and results of lower tier studies such as acute and subacute toxicity tests.

An acute contact LD50 for honey bees is required if the proposed use will result in exposure

of honey bees.

Birds, Acute

The requirement for a measurement of acute oral toxicity to birds is fulfilled based on one

acceptable study, which indicates slight toxicity. Results follow in Table 36. (MRID No. 00079523)

Table 36: Avian Acute Oral Toxicity 

Species % Test Material (TGAI) LD50 (mg/kg) Fulfills Guidelines

Bobwhite quail 92.3 1499 Yes

Birds, Subacute

The requirement for a measurement of subacute dietary toxicity is fulfilled based on two

acceptable studies, which indicate that the chemical is practically nontoxic to birds. Results follow

in Table 37. (MRID Nos. 43087101, 43087001)

Table 37: Avian Subacute Dietary Toxicity 

Species % Test Material (TGAI) LC50 (mg/L) Fulfills Guidelines

Bobwhite Quail 95.4 >5620 Yes

Mallard Duck 92.3 >5620 Yes
117

Birds, Chronic

When birds are expected to be exposed to pesticides for long periods of time or exposed

during the breeding and nesting season avian reproduction studies are sometimes required. Avian

reproduction studies for alachlor are required based on the following criteria: 

C Birds are expected to be subjected to repeated or continued exposure to alachlor and or its

degradates preceding or during breeding season. Alachlor is generally applied in the early

spring months when birds are most actively breeding.

C Alachlor and its metabolites or degradates are stable in the environment to the extent that

potentially chronically toxic amounts may be present in avian feed.

C In a rat teratological study both maternal and developmental effects were observed at 400

mg/kg/day (MRID No. 00043645)

C Reproduction studies with acetochlor, a pesticide whose chemical structure is very similar to

alachlor, have shown reproductive effects to mallard duck at 150 ppm and bobwhite quail at

750 ppm (MRID Nos. 43383101, 43383102). In a partially acceptable reproduction study

conducted with metolachlor on mallard duck, eggs in 10, 100, and 1000 ppm test

concentrations showed eggshell thinning (MRID No. 0162292). 

Mammals

Ecological effects data on toxicity data to mammals will not be required for alachlor at this

time. Available toxicity data on rats (health effects data requirement) indicate an acute LD50 of 930

mg/L. Mammalian LD50s are not used directly to determine whether LOCs are exceeded, but do

provide some indication of level of toxicity. The available data indicates that alachlor is slightly toxic

to small mammals. 

Insects

Honey bee acute contact studies conducted with technical ingredient and 42% formulation

products have been reviewed. These studies indicated low toxicity toward honey bees, with LD50

levels greater than 36.2 μg ai/bee for the technical and greater than 100 μg ai/bee for the formulated

product. (MRID Nos. 00074486 and 00028772)

Table 38: Toxicity to Honey Bees

%Test Material (TGAI) LD50 (μg ai/bee) Fulfills Guidelines

Technical >36.2 Yes

42.2% Formulation >100 Yes
118

b. Aquatic Animals

Freshwater Fish

To evaluate toxicity of a pesticide to freshwater fish, LC50 measurements are required for two

species, using technical grade active ingredient. One study should use a cold water species, preferably

rainbow trout. The other should use a warm water species, preferably bluegill sunfish. Chronic

toxicity testing is required for evaluation of possible effects to growth or reproduction of fish exposed

to persistent pesticides. This requirement is fulfilled by Early Life-stage Testing of one species of

freshwater fish.

The data requirement is fulfilled for alachlor based on studies submitted. Studies submitted

indicate moderate toxicity to warm- and cold- water fish. LC50 values are displayed in Table 39.

Precautionary toxicity statements are required on labels based on MRID No. 43862601 which shows

alachlor to be highly toxic on a chronic basis to freshwater fish growth, reproduction and

development. Acute toxicity of alachlor and tested formulations is moderate. (MRID Nos.

00023615, 00023616, 00028549, 00028550, 00028551, 00028553, 00028554, 00028555, 00031524,

00031525, 40098001)

Table 39: Acute Toxicity to Freshwater Fish

Species % Test Material (TGAI) LC50 (mg/L) Fulfills Guidelines

Toxicity Based on Exposure to Technical Active Ingredient

Bluegill Sunfish 90 2.8 Yes

100 4.3 Yes

Rainbow Trout 90 1.8 Partially

100 2.4 Yes

Toxicity Levels Based on Exposure to End-Use Product

Bluegill Sunfish 43EC 3.2 Partially

45 6.2 Partially

42.4 7.9 Partially

Rainbow Trout 42.5 3.6 Partially

45 3.7 Partially

44 4.2 Partially

43 1.4 Yes
Table 39: Acute Toxicity to Freshwater Fish

Species % Test Material (TGAI) LC50 (mg/L) Fulfills Guidelines

119

43 3.2 Yes

Table 40: Chronic Toxicity To Freshwater Fish in mg ai/L

Species % Test Material NOEL LOEC Fulfills Requirement

Rainbow trout Technical 0.187 0.388 Yes

Toxicity to Freshwater Invertebrates

To evaluate acute toxicity to freshwater aquatic invertebrates, an EC50 measurement is

required based on technical grade active ingredient, preferably using first instar Daphnia magna, or

early-instar amphipods, stoneflies, mayflies, or midges. The requirement is fulfilled based on studies

submitted. Results are displayed in Table 41. The studies submitted indicate moderate to slight acute

toxicity for this category, based on studies reviewed to date. (MRID Nos. 00028549, 00028555,

00031526, 40098001).

Table 41: Toxicity to Freshwater Invertebrates

Species % Test Material

(TGAI)

EC50

(mg/L)

Fulfills Guidelines

Toxicity Based on Exposure to Technical Active Ingredient

Water Flea

Daphnia magna

90 10 Yes

93 21 Yes

Midge 93 3.2 Yes

Toxicity Levels Based on Exposure to End-Use Product 

Water Flea

Daphnia magna

49 33 Partially

45 22 Partially

42.4 27 Partially

43 7.7 Yes

Midge 45 2.5 Yes
120

Chronic toxicity to freshwater invertebrates is determined by exposing one species of

freshwater invertebrate, preferably Daphnia magna, to the pesticide for a full generation and

observing effects on growth and reproduction. In 21-day full lifecycle testing alachlor was shown to

be highly chronically toxic to growth and reproduction of freshwater invertebrates. Chronic LOEC

and NOEC values are displayed in Table 42. Based on the high chronic toxicity of this pesticide

appropriate environmental warning labels are required. (MRID No. 43774707)

Table 42: Chronic Toxicity Based on Exposure to Technical Active Ingredient 

Species % Test Material 

(TGAI)

LOEC

mg ai/L

NOEC 

mg ai/L

Fulfills

Requirement

Water Flea, 

Daphnia magna

94.6 0.23 0.11 Yes

Acute Toxicity of Pesticide Metabolites to Freshwater Animals

Aquatic testing with metabolites of pesticide compounds is requested when metabolites are

likely to be persistent in the aquatic habitats in amounts greater than or equal to the parent compound.

Four studies have been submitted to aid in characterization of the acute toxicity of alachlor sulfonic

and oxanilic acids to freshwater invertebrate and fish species. The studies indicate that these

degradate compounds display low acute toxicity to the tested species. The submitted studies are

summarized in Table 43. (MRID Nos. 43774703, 43774704, 43774705, and 43774706) 

Table 43: Acute Testing with Alachlor Metabolites

Species Tested Degradate and % ai LC50/EC50

(mg ai/L)

Fulfills Guidelines

Daphnia magna Sulfonic acid, 91.5% EC50>104 mg/L Yes

Oxanilic acid, 92.4% EC50>95 mg/L Yes

Rainbow trout Sulfonic acid, 91.5% LC50>104 mg/L Yes

Oxanilic acid, 92.4% LC50>95 mg/L Yes

Estuarine and Marine Animals

The use pattern of alachlor includes applications to major crops that are sometimes grown in

close proximity to estuarine and marine environments. 

The toxicity measurements required are a 96-hour LC50 for an estuarine fish, a 96-hour LC50

for shrimp or mysid, and either a 48-hour embryo-larvae study or a 96-hour shell deposition study
121

with an estuarine mollusk species. The data requirement is fulfilled for alachlor based on the studies

submitted (MRID Nos. 44524301, 44524302, 44524303). LC50/EC50 values are shown in Table

44.

Table 44: Acute Toxicity to Estuarine/Marine Species

Species % Test Material (TGAI) LC50/EC50

 (mg/L)

Fulfills Guideline

Sheepshead minnow 93.8 LC50=3.9 Yes

Mysid 93.8 LC50=2.4 Yes

Eastern Oyster 93.8 EC50=1.6 Yes

A study submitted to the Agency (Kirby-Smith, et. al., 1993), indicates that, in general, there

were no significant differences in diversity, numbers and/or biomass between those creeks and

estuaries that received pesticidal run-off (farm creeks) and those that didn’t (forested creeks). The

data derived from this study is confounding because results did not compare with laboratory toxicity

data and EEC estimates. During the course of this study there did not appear to be any significant

chronic adverse effects in terms of species diversity, biomass, energy transfer or nutrient cycling,

occurring in the system.

c. Plants

Data from studies submitted to the Agency, though incomplete, indicate high toxicity to

aquatic and terrestrial plants.

Terrestrial Plants

Studies were required to establish toxicity to nontarget terrestrial plants. Two studies were

received. Of the ten species of terrestrial plants tested, seven had EC25 levels for vegetative vigor less

than maximum permitted rates on present labels. Seedling emergence was also effected in most of

the species tested. Based on the data provided, alachlor is highly toxic to nontarget terrestrial

plants. (MRID Nos. 42468601, 42468701)

Table 45: Toxicity to Terrestrial Plants

Measurement Endpoint Most Sensitive

Species Tested

NOEL (lbs a.i./A) EC25(lbs a.i./A)

Vegetative Vigora

Phytotoxicity Ryegrass 0.019 undetermined
Table 45: Toxicity to Terrestrial Plants

Measurement Endpoint Most Sensitive

Species Tested

NOEL (lbs a.i./A) EC25(lbs a.i./A)

122

21-Day Survival Onion 0.22 0.31 

21-Day Height Ryegrass 0.037 0.12

21-Day Weight Ryegrass 0.037 0.044

Germination and Growth

6-Day Seed Germination Cabbage 0.67 undetermined

6-Day Seedling Emergence Ryegrass 0.019 0.04 

21-Day Survival Onion 0.037 0.011 

Phytotoxicity Lettuce 0.0093 undetermined

Height Ryegrass 0.0023 0.011 

Weight Ryegrass 0.0023 0.0067

a. Based on a supplemental study with 94.6% active ingredient that fulfills guideline requirements. 

b. Based on a supplemental study with 94.2% active ingredient that fulfills guideline requirements. 

Aquatic Plants

Studies were required to establish toxicity to nontarget aquatic plants. The requirement is

partially fulfilled by the single study submitted. However, to completely fulfill data requirements for

aquatic plant testing additional studies must be submitted for acute toxicity to an aquatic macrophyte,

a marine diatom, a blue-green algae and a freshwater diatom. Based upon the one study available,

alachlor is highly toxic to aquatic plants. (MRID No. 42763801) Also, effects on aquatic plants

are expected to result in indirect effects on aquatic animals, e.g., by habitat modification or restricted

food supply. 

Table 46: Toxicity to Aquatic Plants

Species Tested %Test

Material

Toxicity (μg/L) Fulfills

Guidelines

Freshwater Green alga

Selenastrum capricornutum

98.6 NOEL=0.35

LOEL=0.69

EC50=1.64

(growth effects)

 Yes,

partially
123

d. Conclusions

The available toxicity data for alachlor, indicate that it is:

C Slightly to practically non-toxic to birds on an acute oral basis (LD50 of 1500 mg/kg), but

chronic data are not available.

C Slightly toxic to mammals, based on a rat study (LD50 of 930 mg/kg).

C Slightly toxic to honey bees (LD50 >36 μg/bee).

C Slightly to moderately toxic on an acute basis to freshwater aquatic animals (LC50 /EC50 1-33

ppm).

C Highly to moderately toxic to freshwater aquatic animals on a chronic basis (NOEC$0.1 ppm,

LOEC$0.2 ppm).

C Moderately toxic to saltwater fish (LC50 3.9 ppm), moderately toxic to saltwater mysid (LC50

2.4 ppm) and moderately toxic to shellfish (EC50 1.6 ppm).

C Highly toxic to aquatic plants (based on a single species tested: NOEL=0.35 ppb, LOEL=0.69

ppb, EC50=1.64 ppb).

Therefore, a potential risk to nontarget terrestrial and aquatic plants, and endangered plant

species exists. Additionally, the available information on the major alachlor degradates indicate that

the degradates appear to be less toxic to aquatic organisms than the parent.

3. Environmental Fate Data

The following studies provide the basis for the Environmental Fate Assessment.

a. Degradation

GLN 161-1 Hydrolysis: 

In an acceptable study, [14C] Alachlor (carbonyl labeled) applied at 50 ppm was relatively

stable in sterile commercial pH 3, 6, and 9 buffer solutions, natural lake water, and deionized water

that were incubated in the dark at 25EC for 30 days. [14C] Alachlor comprised 97.5-98.7% of the

applied radioactivity in all test solutions, with no discernible pattern of decline. The degradate 2',6'-

Diethyl-N-methoxymethyl acetanilide was #1.57% of the applied.

As part of the same study, [14C] alachlor, at 2 ppm, degraded very slowly in nonsterile lake

water, when incubated at an unspecified temperature for 30 days. After 30 days of treatment,

alachlor was 88.8% of the applied concentration in the test solution. Five nonvolatile compounds

were identified, at #2.7% of the applied. (MRID No. 00134327)
124

GLN 161-2 Photolysis in Water: 

This data requirement will be waived based on the UV absorption spectrum of alachlor in

water. The current policy is to concur with waivers for this requirement when the electronic

spectrum of the chemical does not show significant absorption between 290 and 800 nm, because

photodegradation can only take place when there is an overlap between absorption regions of the

spectrum of the chemical and the irradiation spectrum of the light source. A submitted study

indicated that the UV absorption spectrum of alachlor in water shows no absorption at wavelengths

above 290 nm. (MRID No. 00023012)

GLN 161-3 Photodegradation on Soil: 

The Agency will require no additional data to support the Photodegradation on Soil data

requirement at this time. Although the Agency does not have any information about the photolytic

behavior of any of the major degradates of alachlor at this time, an acceptable study will not be

required because the absorption spectrum of the chemical in water does not show significant

absorption at wavelengths above 290 nm.

b. Metabolism

GLN 162-1 Aerobic Soil Metabolism: 

Three different studies conducted on various soil types have shown similar half-lives, ranging

from 6 to 21 days. The degradation products were identified only in two of the studies, one of which

is acceptable and the other is supplemental. Three of the four major degradates were observed in

both studies. The compound (N-methoxymethyl-N-(2,6-diethylphenyl)-2-amino-2-oxoethyl)

sulfinylacetic acid, which was up to 15.9% of the applied in one supplemental study (MRID No.#

00101531), was not observed in the acceptable study (MRID No. 00134327). All major metabolites

were monitored in the available Terrestrial Field Dissipation study.

In an acceptable study [14C] alachlor applied at 2 ppm degraded with estimated half-lives of

2-3 weeks in silt, loamy sand, and silt loam soils incubated in the dark at 25EC and 75% of field

moisture capacity for 175 days. In the silt loam soil, alachlor was 87.7% or the applied at the

initiation of the study, 47.4% at 21 days, and 1.6% at 175 days. In the loamy sand, alachlor was

98.5% of the applied at 0 days, 52.4% at 14 days, and 2.5% at 175 days. In the silt soil, alachlor was

99.0% of the applied at day 0, 40.4% at day 14, and 0.7% at 175 days.

Four degradates were detected, with significant concentrations ($ 10% of the applied):

C Alachlor DM-oxanilic acid was a "water soluble" metabolite that increased gradually to a

maximum of 5.3% of the applied at 50 days post-treatment in the silt loam, it decreased to

3.9% at 175 days. It increased to a maximum of 15.8-17.0% of the applied at 175 days posttreatment (last test interval) in the loamy sand and silt soils;
125

C Alachlor oxanilic acid was a "water soluble" metabolite, and was a maximum of 12.7-22.4%

of the applied at 28-50 days post-treatment in all soil types and decreased to 2.9-13.4% of

the applied at 175 days post-treatment;

C Alachlor ESA was a "water soluble" metabolite, which increased to a maximum of 24.9% of

the applied at 50 days post-treatment in the silt loam, 16.9% of the applied at 175 days posttreatment in the loamy sand, and 16.0% of the applied at 21 days post-treatment in the silt

soil. It decreased to 11.2-18.6% of the applied at 175 days post-treatment in the silt loam and

silt soils.

C 2',6'-diethyl-2-hydroxy-N-methoxymethylacetanilide was the only major "methylene chloride

soluble" degradate and increased to a maximum of 6.7-10.2% of the applied at 7-21 days

post-treatment and decreased thereafter to #1.1% of the applied at 175 days in all soil types.

Nine other degradates were also identified, at #10% of the applied. After 175 days

incubation, 14CO2 was 16.17-30.00% of the applied. [14C] volatiles were #1.15% of the applied, and

unextracted [14C] residues totaled 19.25-20.76% of the applied. (MRID No. 00134327)

In a second study (found to be supplemental), [14C] alachlor (phenyl ring-labeled) applied at

2 ppm degraded with half-lives of 6-12 days in silt, loamy sand, and silt loam soils incubated in the

dark at 25EC for 62 days. The soils were also treated with [14C] alachlor encapsulated in a polyurea

polymer. The rate of degradation is similar for the encapsulated [14C] alachlor, with half-lives of 8-11

days.

Four major degradates were identified in the soil. These degradates were observed in all three

soil types at 62 days; however, testing at various test intervals (monitoring through time) was

performed only for the silt soil:

C Alachlor DM-oxanilic acid comprised a maximum of 14.4% of the applied radioactivity in the

silt soil at 62 days post-treatment. It comprised 2.9-7.3% of the applied at 62 days in the

loamy sand and the silt loam;

C Alachlor oxanilic acid comprised a maximum of 9.7-10.0% of the applied radioactivity in the

silt soil at 20 days post-treatment. It decreased to #3.7% of the applied at 62 days in the

loamy sand and the silt loam;

C Alachlor sufinylacetic acid comprised 15.9-16.2% of the applied radioactivity in the silt loam

soil at 62 days post-treatment. It was a maximum of 12.6-13.3% of the applied in the silt soil

at 20 days post-treatment, decreasing to #9.7% at 62 days; and
126

C Alachlor ESA comprised a maximum of 6.5% of the applied radioactivity in the silt soil at 30

days post-treatment and #5.1% at 62 days. It was 2.7-4.1% of the applied in the loamy sand

and silt loam at 62 days.

This study provides supplemental information about the rate of degradation of alachlor and

the identity of alachlor degradates under aerobic conditions. This study is deficient because up to

22.3% of the applied radioactivity was not characterized. (MRID No. 00101531)

In a third study (also supplemental) [14C] alachlor applied at 4 ppm degraded appreciably, with

a half-life of <18 days in sandy loam, silt loam, and silty clay loam nonsterile soils incubated at #32EC

in a greenhouse. [14C] Alachlor was #0.5 ppm in all three soil types 72 days after treatment. The

degradate 2-chloro-2',6'-diethylacetanilide was detected at all sampling intervals at #0.8 ppm, with

no definite pattern of formation or decline.

This study was conducted in a greenhouse. It provides supplemental information about the

aerobic soil metabolism of alachlor by identifying one alachlor degradate. The study is deficient when

evaluated according to current guidelines because it was conducted in the greenhouse, and material

balances could not be confirmed. (MRID No. 00023014)

c. Mobility/Leachability of Alachlor

GLN 163-1 Mobility, Leaching and Adsorption/Desorption: 

Based upon the studies available and the structural features of the chemicals, it appears that

alachlor degradates, as well as parent alachlor, have a high potential to leach.

An acceptable study partially satisfies the requirement by providing information about the

mobility of unaged alachlor. To satisfy the data requirement a supplemental Batch Equilibrium study

was submitted for alachlor ESA, which is the major degradate observed in the aerobic soil metabolism

studies.

[

14C] Alachlor (carbonyl labeled), at 3.5 lb a.i./A, was very mobile in 30 cm columns of silt,

sand, and loamy sand soils that were leached with 20 inches of water. The leachate from the silt,

sand, and loamy sand soil columns contained 40.9-96.9% of the applied radioactivity. This

radioactivity was "mainly" alachlor. The following degradate was identified in these leachates, but

not quantified: 2',6'-diethyl-N-methoxymethylacetanilide.

[

14C] Alachlor was mobile in columns of silt loam soil treated under similar conditions. The

leachate from the silt loam soil contained 0.5-0.6% of the applied radioactivity. The radioactivity

remaining throughout the soil columns increased from 1.9-5.4% of the applied in the 0- to 2-cm

segment, to 10.9-12.9% in the 10- to 14-cm segments, and declined to 0.1% in the 28- to 30-cm

segment. The following compounds were detected in the leachates at 5-23% of the recovered
127

radioactivity: 2',6'-diethyl-N-methoxymethylacetanilide, 2-chloro-2',6'-diethylacetanilide, and 2',6'-

diethyl-N-methoxymethyl-2-methylthioacetanilide.

The analysis of selected soil extracts of all four soils indicated that the radioactivity was

"mainly" alachlor. There was no clear correlation between the mobility of alachlor and the soil

composition; however, it appears that higher organic matter contents favor adsorption of the chemical

to the soil. 

Although this study had been found acceptable and provides information about the mobility

of parent alachlor, the following details are noted because they could have had an effect on the

observed results: The columns were packed using a wooden dowel; it is not reported if the columns

were saturated prior to leaching. In addition, it is reported that the water "was added at a rate slower

than the infiltration capacity of the soil." These conditions could have affected the observed leaching

behavior. The parent alachlor could have leached even more under saturated flow conditions which

would be the maximum flow rates. (MRID No. 00134327)

In a leaching study, [14C] alachlor residues leached through the columns, with .96%, .51%,

and 0% of the recovered having leached through a gravelly sand, sandy loam, and a silty clay loam

soil columns, respectively. The soil columns measured 20 cm (8 inches, recommended 30 cm), and

were leached with 10 inches of water (recommended 20 inches). This study was considered

scientifically valid in the original reviews. However, the Agency now believes that these studies only

provide supplemental information, since leaching and soil retention were reported based on 14C rather

than concentrations of alachlor and its degradates. The study indicates a high level of leaching in

sand, sandy loam, and silty clay loam. (MRID Nos. 00027139, and 00027140)

Based on a supplemental Adsorption/Desorption experiment [14C] alachlor, at 1-10 ppm,

appears to have a high mobility in three soil types. The Kd values, calculated based on [14C] instead

of actual alachlor concentrations, decreased with a decrease in soil organic matter. The mean Kd

values were 3.74 for a silty clay loam, 2.88 for sandy loam, and 0.80 for a gravelly sand.

In a supplemental column leaching study alachlor applied at 5 kg ai/A appeared to be very

mobile in a Lakeland sand, with 59% of the applied alachlor recovered from the leachates of a 30 cm

soil column, eluted with 8 inches (20 cm) of water. Alachlor was less mobile in other soils tested,

with maximum leaching depths of 18 cm, 10 cm, and 4 cm in Collenbey sand, silt loam, and sandy

clay loam columns, respectively. The level of leaching appeared to be related to the percent organic

matter, with lower leaching of the soils having higher organic matter.

However, the study does not meet the Subdivision N Guidelines because the columns were

eluted with only 8 inches of water. (Subdivision N Guidelines recommends elution with 20 inches

of water.) In addition, no attempts were made to measure possible degradates or total residues.

Therefore, the Agency is concerned about the validity of the study since insufficient elution water was

applied to demonstrate the mobility of alachlor in the soils. This study is now deemed supplemental
128

and gives an indication of the level of leaching in sandy clay loam, silt loam, and sand. (MRID No.

00078301)

Based on supplemental column leaching studies, aged (30 days) uncharacterized [14C]

residues of alachlor were mobile in 30 cm columns with sandy loam soil, treated at 3.5 lb a.i./A, and

leached with 20 inches of water. The radioactivity recovered in the leachate totaled 29.1-31.5% of

the applied. Approximately 10 compounds were isolated from the leachates each at #0.7% of the

applied radioactivity. The major component found in the soil samples was [14C] alachlor.

This portion of the study (aged) is not acceptable, because the soil was aged for 30 days,

which may be a period of time considerably longer than one half-life. The aerobic soil metabolism

studies show estimated half-lives between 2 and 3 weeks. After the aging period, and prior to

leaching, the soil was not characterized; therefore, it is not possible to determine if either sufficient

parent compound remained at the time of leaching, or what was the ratio of the degradates formed.

(MRID No. 00134327)

d. Mobility of Alachlor Degradates

Mobility and Adsorption/Desorption of Alachlor ESA:

Based on batch equilibrium studies, uniformly phenyl ring-labeled [14C]-alachlor ESA (sodium

salt), at approximately 6.0, 1.0, 0.2, and 0.04 Fg/mL, was determined to be very mobile in Sable silty

clay loam:calcium chloride solution slurries (1:5) that were equilibrated in the dark for 24 hours at

approximately 25EC. Freundlich Kads value was 0.45 and KOC value was 15. Following one

desorption step, Freundlich Kdes value was 1.43. Material balance ranged from 95.8 to 110.9% of the

applied for the definitive study.

Based on batch equilibrium studies, uniformly phenyl ring-labeled [14C]-alachlor ESA, at

approximately 6.0, 1.0, 0.2, and 0.04 Fg/mL, was determined to be very mobile in Sarpy sandy loam,

Spinks sandy loam, and Katy loam:calcium chloride solution slurries (1:5) that were equilibrated in

the dark for 24 hours, at approximately 25EC. Accurate Freundlich Kads values could not be

calculated because levels of adsorbed [14C]-alachlor ESA metabolite were very low. Adsorption

values in these three soils were approximately 0% (MRID No. 44405301).

The study on alachlor ESA does not fully fulfill the data requirement, because Freundlich

adsorption values could not be calculated in three of the soils. However, the study provides

supplemental information about the mobility of alachlor ESA, which has been detected in greater

concentrations than parent alachlor. The Agency believes that a new study would not provide new

information about the mobility of alachlor ESA other than confirming that this degradate is very

mobile; therefore, no additional data on the mobility of alachlor ESA are required at this time.

The registrant has submitted Adsorption/Desorption studies for two propachlor soil

metabolites. Propachlor is structurally similar to alachlor. The mobility characteristics of alachlor
129

and propachlor, as well as other physico-chemical characteristics are similar as well. The registrant

proposed to use the mobility data on propachlor degradates as surrogate data for alachlor degradates.

This was accepted by the Agency since (1) the propachlor degradates are structurally similar to

alachlor degradates, and (2) the propachlor degradates are very mobile, which is comparable to the

available information on the mobility of alachlor ESA. Results obtained for the propachlor degradates

are as follows:

Based on batch equilibrium studies, propachlor oxanilic acid was determined to be very mobile

in loamy sand, sandy loam, loam, and silty clay loam soil: solution slurries. Freundlich Kads values

ranged from 0.03 to 0.08. Table 47 summarizes the results obtained in the study. (MRID No.

42485703)

Table 47: Mobility and Adsorption/Desorption for Propachlor Oxanilic Acid

Kads KOC KDes KOC

loamy sand 0.03 8 4.48 1120

sandy loam 0.04 2 15.86 886

loam 0.08 7 4.34 391

silty clay loam 0.06 10 20.91 3428

An acceptable propachlor sulfonic acid study is available, which can be used to partially satisfy

the data requirement for alachlor. Based on batch equilibrium studies, propachlor sulfonic acid was

determined to be very mobile in sand, sandy loam, loam, and silty clay loam soil:solution slurries.

Freundlich Kads values ranged from 0.03 to 0.07. Table 48 summarizes the results obtained in the

study. (MRID No. 42485704)

Table 48: Mobility and Adsorption/Desorption for Propachlor Sulfonic Acid

Kads KOC KDes KOC

sand 0.03 7 1.33 317

sandy loam 0.06 6 6.24 624

loam 0.05 5 1.73 156

silty clay loam 0.07 3 1.23 47

Mobility characteristics compared for alachlor and propachlor: 

An examination of the mobility characteristics of alachlor and propachlor show that both are

very mobile. Generally, propachlor is more mobile than alachlor (except in the Ray silt). It is
130

observed that %CEC (% cation exchange capacity) and %OM (% organic matter) are good

predictors of alachlor mobility (higher mobility when %CEC is lower, and higher mobility when

%OM is lower). This trend is only general for propachlor. The Agency believes that for both

alachlor and propachlor degradates, that the negative charges play an important role in predicting the

mobility.

Table 49: Mobility Characteristics for Alachlor

Soil type % sand % silt % clay % OM % CEC %

radioactivity

found in

leachates

sand 86.0 11.0 1.8 0.7 5.1 86.7-96.9

silt 4.6 84.2 10.0 1.2 10.4 78.2-82.2

loamy sand 75.1 17.8 4.8 2.4 11.3 40.9-43.4

silt loam 2.4 68.0 25.3 3.4 24.6 0.5-0.6

Table 50: Mobility Characteristics for Propachlor

Soil type % sand % silt % clay % OM % CEC Ave. %

radioactivity

found in

leachates

Lintonia

sand

86.0 11.0 1.8 0.7 5.1 83.1-95.9

Ray silt 4.6 84.2 10.0 1.2 10.4 40.6-71.4

Spinks

loamy sand

75.1 17.8 4.8 2.4 11.3 71.0-84.0

Drummer

silt loam

2.4 68.8 25.3 3.4 24.6 2.9-7.9

The Agency believes that the mobility requirements for alachlor metabolites have been

partially satisfied with the submission of mobility data of the propachlor degradates: propachlor

oxanilic acid and propachlor sulfonic acid. The Agency believes that these degradates show

substantial structural similarity to alachlor degradates, therefore they can be used for a preliminary

assessment of the mobility of alachlor degradates. The Agency believes that the available data
131

confirms that all the four major degradates of alachlor are very mobile under normal environmental

conditions.

e. Volatility

GLN 163-2 and 163-3 Laboratory and Field Volatility:

This data requirement was waived, based on the relatively low vapor pressure and levels of

volatiles in the aerobic soil metabolism study.

Alachlor has a vapor pressure of 2.2 x 10-5 mm Hg at 24EC (MRID No. 00152209). Since

this value is relatively low, volatility may not be an important route of dissipation for alachlor. In

addition, the acceptable Aerobic Soil Metabolism study (MRID No. 00134327) showed the presence

of small amounts of [14C] volatiles (#1.15% of the applied after 175 days of incubation). In a

supplemental aerobic soil metabolism study (MRID No. 00101531) [14C] volatiles were #4.84% of

the applied after 40-62 days. This suggests that volatilization is not a significant route of dissipation

for alachlor.

f. Field Dissipation

GLN 164-1 Terrestrial Field Dissipation: 

Field dissipation has been evaluated at sites in Chico and Hickman, California. (MRID Nos.

42528001, 42528002, 42528003, 42528004, 43774701) Both terrestrial field dissipation studies

were conducted in California, despite the fact that alachlor is widely used throughout the United

States. These two studies are not adequate to fully characterize the range of field conditions to which

alachlor may be exposed. Despite this fact, a new additional terrestrial field dissipation study will not

be required. The Agency believes that a new study would not provide substantial new information.

The study conducted in Chico, California is acceptable and can be used to partially satisfy the

Terrestrial Field Dissipation (164-1) data requirement. Alachlor (Lasso ®4-EC), applied once at 4

lb a.i./A, dissipated with an observed half-life of approximately 11 days from a plot of loam/sandy clay

loam soil in Chico, California, that was planted to corn immediately after treatment. Alachlor was

detected at a depth of 18- to 24-inches (at test intervals 7 and 14 days). In the 0- to 6-inch soil depth,

alachlor averaged 0.781-0.798 ppm at 0-1 days post-treatment, 0.641 ppm at 7 days, and 0.350 ppm

at 11 days. Two samples showed $0.124 ppm at 14 days, both in the 12- to 18- and 18- to 24-inch

soil depths. In addition, five minor detections occurred at 36- to 48-inch soil depth at #0.016 ppm

at 11-18 days. The rainfall plus irrigation totaled 6 inches through 18 days post-treatment.

The following degradates were detected in the soil:

C Alachlor oxanilic acid was detected through 44 days post-treatment in the 0- to 6- and

6- to 12-inch soil depths, at averages #0.047 ppm. There were 15 individual
132

detections through 44 days in the 0- to 6-inch soil depth and 10 individual detections

through 21 days in the 6- to 12-inch soil depth. There were also sporadic detections

in the soil depths up to 36- to 48-inch at #0.023 ppm. These included 5 detections

in the 12- to 18-inch soil depth (14-120 days), 2 detections in the 18- to 24-inch soil

depth (18 and 180 days), and 2 detections in the 36- to 48-inch soil depth (44 days);

C Alachlor sulfinylacetic acid was detected from 7 through 44 days post-treatment in

the 0- to 6- and 6- to 12-inch soil depths, at averages #0.039 ppm. There were 13

individual detections through 44 days in the 0- to 6-inch soil depth and 11 individual

detections through 44 days in the 6- to 12-inch soil depth. There were 5 sporadic

detections in the soil depths up to 18- to 24-inch at #0.020 ppm at 14 and 18 days;

C Alachlor ESA was detected from 1 through 44 days post-treatment in the 0- to 6- and

6- to 12-inch soil depths, at averages #0.027 ppm. There were 14 individual

detections through 44 days in the 0- to 6-inch soil depth, 10 individual detections

through 90 days in the 6- to 12-inch soil depth; and 4 detections each in the 12- to 18-

and the 18- to 24- soil depths (at #0.022 ppm) at 14-78 days. Two sporadic

detections at #0.011 ppm were observed in the 24- to 36-inch soil depth, at 18, and

44 days.

C Alachlor DM-oxanilic acid was detected sporadically at #0.061 ppm through 90 days

after treatment, in the 0- to 6- and 6- to 12-inches depths. In addition, there was 1

detection each in the 12- to 18- and the 18- to 24-inch soil depths (90 and 44 days),

and 2 detections in the 24- to 36-inch soil depth (14 and 78 days).

Three samples were tested per test intervals. The lowest limit at which the method was

validated for each metabolite is 0.01 ppm. Detections below this level were reported as <0.01 ppm.

Examination of the soil composition data of the Chico plot shows an increasing percent of clay

with soil depth (to a maximum of 65% clay in the 24- to 36-inch soil depth). This "clay pan" reduces

the flow of water into deeper soil layers, decreasing the possibility of leaching of both parent alachlor

and its degradates. It is possible that under conditions that would favor the flow of water into deeper

soil layers, further leaching would have been detected.

The study conducted in Hickman, California is acceptable and can be used to partially satisfy

the Terrestrial Field Dissipation data requirement.

Alachlor (Lasso® E.C.), applied once at 4 lb a.i./A, dissipated with a registrant-calculated

half-life of 6.2 days from the 0-6 inch soil depth of a bareground plot of sandy loam soil in Hickman,

California. The field was bareground to simulate preemergent application to a crop. In the 0-6 inch

soil depth, alachlor averaged 1.363-1.458 ppm at 0-1 days post-treatment, 0.932 ppm on day 7 after

application, and 0.220 ppm on day 21 after application. Alachlor remained mostly in the 0-6 inch soil
133

depth. Detections averaging 0.018-0.046 ppm were reported in the 6-12 inch soil depth on days 0

and 1 after application.

The following degradates were detected in the soil:

C Alachlor DM-oxanilic acid was detected in the 0-6 inch soil depth from day 1 through

day 366 after treatment at average levels from 0.006-0.048 ppm (no clear pattern of

formation or decline). The chemical was detected in the 6-12 inch soil depth only on

day 182 after application, with an average value of 0.004 ppm.

C Alachlor oxanilic acid was detected in the 0-6 inch soil depth from day 0 through day

366 after application at average levels from 0.005 to 0.058 ppm, with no clear pattern

of formation and decline. At three test intervals, detections were reported in the 6-12

inch soil layer. On days 0, 125, and 182, the oxanilate levels were 0.004, 0.004, and

0.013 ppm, respectively. The chemical was also detected in the 12-18 and 18-24 inch

soil layers on day 182 after application, with average values of 0.007, and 0.008,

respectively.

C Alachlor sulfinylacetic acid was observed at low levels in the 0-6 inch soil layer from

day 1 to 182 after application, at average levels ranging from 0.002 to 0.017 ppm.

In addition, the chemical was detected in the 6-12 and 18-24 inch soil layers on day

182 after application, with average values of 0.004 ppm in both cases,

C Alachlor ESA was observed at low levels from day 0 through day 366 after

application at average levels ranging from 0.003-0.010 ppm. Detections were also

reported in the 6-12 inch soil depth on days 182 and 366 after application, with

average values of 0.004 and 0.008 ppm, respectively. Furthermore, the chemical was

detected in the 12-18 inch soil depth on day 182 after application, with an average

value of 0.003 ppm

Another study conducted at Madera, California was considered invalid since the alachlor

concentrations found at all levels in the soils was #0.1 ppm. The application rate was 4 lb a.i./A.

When conducting a Terrestrial Field Dissipation study, the soils are sampled immediately after

treatment. Generally, it is expected that the highest concentration of active ingredient would be

observed at that test interval. Thereafter, a pattern of decline should be observed and a half-life is

calculated. Since the alachlor concentrations found at all levels in the soils was #0.1 ppm, there was

no pattern of decline. Thus, this study is not representative of typical behavior for the test conditions.
134

g. Bioaccumulation

GLN 165-4 Bioaccumulation in Fish:

This data requirement was waived. Alachlor has a relatively high water solubility (240 ppm),

and a low octanol/water partition coefficient of 434 (one study reports as low as 35). Chemicals with

these physico/chemical properties are not expected to bioaccumulate substantially in fish. Therefore,

the Agency will require no additional information on the Bioaccumulation in Fish (165-4) data

requirement for alachlor at this time.

h. Spray Drift

GLN 201-1 and 201-2 Spray Drift/Droplet Spectrum and Field Evaluation:

Alachlor is highly toxic to nontarget plants. Since alachlor can be applied aerially, data to

satisfy 201-1 and 201-2 was required in a 1991 DCI. The Spray Drift Task Force (SDTF), a

consortium of pesticide registrants, has submitted to EPA a series of studies intended to characterize

spray drift potential due to various factors, including application methods, equipment, meteorological

conditions, crop geometry, and droplet characteristics. EPA is currently evaluating these studies,

which include ground spray as well as aerial application methods. After its review of the studies, the

Agency will determine whether a reassessment of the potential risks from the application of alachlor

to nontarget organisms is warranted. The results would be used to assess the extent of exposure to

nontarget plants. This data requirement is not satisfied, and is being held in Reserve, pending the

evaluation of the work of the industry's SDTF. The registrant is a member of the SDTF.

4. Environmental Fate Assessment

Based on acceptable and supplemental studies, the following conclusions can be drawn:

Alachlor is stable to abiotic processes (hydrolysis, photolysis in aqueous media, or

photodegradation on soil). The major dissipation routes for the chemical appear to be microbially

mediated degradation and leaching. Alachlor is degraded at moderate rates (t1⁄2. 2-3 weeks) in

aerobic soils, with several degradates observed, including alachlor DM-oxanilic acid, alachlor ethane

sulfonic acid (alachlor ESA), alachlor oxanilic acid, and alachlor sulfinylacetic acid. Currently the

Agency does not have valid Kd's for alachlor. The registrant indicated that a KOC of 124 has been

reported by USDA/ARS in their Internet Web site. However, the Agency has not reviewed the study

used to determine the KOC. The column leaching study for the parent alachlor indicates that it is very

mobile and is not appreciably adsorbed to soils with low organic matter. A batch equilibrium study

on alachlor ESA shows that this degradate is very mobile. The findings in the field confirm the

predicted fate from laboratory studies.

Alachlor dissipated at moderate rates in the field; the observed half-lives of 6 and 11 days are

of the same order of magnitude of the half-lives observed in various aerobic soil metabolism studies
135

(2-3 weeks). It appears that the persistence and mobility of the chemical may increase as it reaches

deeper soil horizons which have lower organic matter content and decreased biological activity, thus

increasing its potential to leach into groundwater.

a. Degradation and Metabolism

Alachlor is a soluble molecule (240 ppm in water at 20EC), with an octanol/water partition

coefficient of 434, and a vapor pressure of 2.2x10-5 mm Hg at 24EC.

Alachlor was stable to hydrolysis in buffered solutions at pH's 3, 6, and 9. It was also

relatively stable in natural lake water. Alachlor does not show any absorption bands above 240 nm

in the absorption spectrum; therefore, it is not expected to undergo photolysis in water or on soil.

In soils, under aerobic soil metabolism conditions, alachlor appears to degrade at a moderate

rate. Results of three different studies (one acceptable and two supplemental) show that alachlor

degrades with half-lives in the range of 6-21 days. The studies include use of different sites, different

formulations, and different soil types. Several degradates were observed in the studies. The major

degradates in the aerobic soil metabolism studies were alachlor DM-oxanilic acid (with a maximum

of 17.0% of the applied), alachlor ESA (24.9% of the applied), alachlor oxanilic acid (22.4% of the

applied), and alachlor sulfinylacetic acid (16.2% of the applied). Of these major "water-soluble"

degradates, alachlor sulfinylacetic acid was not observed in the valid aerobic soil metabolism study.

However, it was observed in a supplemental study. All four degradates appear to be more persistent

than alachlor, since significant concentrations remained in the soils at the end of the aerobic soil

metabolism studies.

CO2 is the ultimate degradate; it comprised 16.17-30.00% of the applied after 175 days in a

valid study. Unextracted residues comprised #20.76% of the applied at the same test interval.

b. Mobility

Based upon both supplemental and acceptable studies, parent alachlor appears to be highly

mobile in soils. In a column leaching study, in three of the soils with lower organic matter, alachlor

was very mobile: silt, sand, and loamy sand soil (0.7-2.4% OM) columns, the leachates contained

40.9-96.9% of the applied radioactivity. In another soil with a higher organic matter content, the

mobility was lower: silt loam soil (3.4% OM), the leachates had only #0.6% of the applied

radioactivity; however, even though the water was added at a rate slower than the infiltration

capacity, substantial downward movement was observed through the column, with a total of 53.5-

57.7% of the applied radioactivity found in the soil segments from 9- to 18-cm.

Since all the major water soluble degradates of alachlor have carboxylic or sulfonic acid

functional groups, which render a negative (anionic) character to the molecule under normal

environmental conditions, it is expected that the degradates will be highly mobile in soils. This is

supported by the available mobility data for the degradates of propachlor (propachlor sulfonic acid
136

and propachlor oxanilic acid), which are structurally similar to the degradates of alachlor; the data

for these degradates of propachlor has been used as surrogate data in lieu of the original alachlor

metabolites. In addition, a batch equilibrium study on alachlor ESA shows that this degradate is very

weakly absorbed. Quantitative results could be obtained in only one of the soils (very mobile in

Sable silty clay loam, Freundlich Kads value was 0.45 and KOC value was 15).

c. Bioaccumulation

Alachlor is not expected to bioaccumulate significantly in fish, based on high solubility (240

ppm), and relatively low octanol/water partition coefficient (434).

d. Field Dissipation

In a Terrestrial Field Dissipation study conducted in Chico, California, alachlor, at 4 lb. a.i./A,

dissipated with a half-life of 11 days from loam/sandy clay loam soil planted to corn. This half-life

is consistent with those reported in various aerobic soil metabolism studies. Most of the alachlor was

found in the 0- to 18-inch soil layers, with occasional detections in the 18- to 24-, 24- to 36-, and 36-

to 48-inch layers (the deepest layer sampled), indicating a large potential for leaching. The four

major water-soluble metabolites of alachlor were also monitored in this study. The soil composition

data in this study shows increasing percent of clay with soil depth (to a maximum of 65% clay in the

24- to 36-inch soil depth). This "clay pan" reduces the flow of water into deeper soils layers,

decreasing the possibility of leaching of both parent alachlor and degradates.

Degradates of alachlor in the Chico Terrestrial Field Dissipation study (alachlor oxanilic acid,

alachlor sulfinylacetic acid, and alachlor ESA derivatives) were detected in the 0- to 6- and 6- to 12-

inch soil depths at average concentrations of 0.010-0.045 ppm. Detections were observed through

36- to 48- soil depth for the oxanilic acid, 18- to 24-inch soil depth for alachlor sulfinylacetic acid and

alachlor ESA, and 6- to 12-inch soil depth for the alachlor DM-oxanilic acid. Generally, detections

of these alachlor degradates occurred through 44-90 days post-treatment in the subsoils. Once

moved to the subsoils, these degradates appear to persist. 

Alachlor, applied once at 4 lb a.i./A, dissipated with a registrant-calculated half-life of 6 days

from the 0-6 inch soil depth of a bareground plot of sandy loam soil in Hickman, California. The field

was bareground to simulate preemergent application to a crop. Alachlor remained mostly in the 0-6

inch soil depth. Detections averaging 0.018-0.046 ppm were reported in the 6-12 inch soil depth on

days 0 and 1 after application.

In the Hickman, California Terrestrial Field Dissipation study the following degradates were

detected: alachlor DM-oxanilic acid, which was detected in the 0-6 inch soil depth from day 1

through day 366 after treatment, and in the 6-12 inch soil depth only on day 182 after application

(with an average value of 0.004 ppm). Alachlor oxanilic acid was detected in the 0-6 inch soil depth

from day 0 through day 366 after application, in addition, at three test intervals, detections were

reported in the 6-12 inch soil layer. Alachlor oxanilic acid was also detected in the 12-18 and 18-24
137

inch soil layers on day 182 after application. Alachlor sulfinylacetic acid was observed at low levels

in the 0-6 inch soil layer from day 1 to 182 after application, and in the 6-12 and 18-24 inch soil layers

on day 182 after application. Alachlor ESA was observed at low levels from day 0 through day 366

after application at average levels ranging from 0.003-0.010 ppm. Detections were also reported in

the 6-12 inch soil depth on two test intervals. Furthermore, alachlor ESA was detected in the 12-18

inch soil depth on day 182 after application, with an average value of 0.003 ppm.

e. Volatility

Volatilization is not expected to be an important route of dissipation for alachlor. The

chemical has relatively low vapor pressure (2.2×10-5 mm Hg). Furthermore, the amount of volatiles

in the aerobic soil metabolism studies were negligible.

f. Spray Drift

The labels indicate that alachlor may be applied aerially. No alachlor-specific spray drift

studies were reviewed. The Spray Drift Task Force (SDTF), a consortium of pesticide registrants,

has submitted to EPA a series of studies intended to characterize spray drift potential due to various

factors, including application methods, equipment, meteorological conditions, crop geometry, and

droplet characteristics. EPA is currently evaluating these studies, which include ground spray as well

as aerial application methods. After its review of the studies, the Agency will determine whether a

reassessment of the potential risks from the application of alachlor to nontarget organisms is

warranted.

5. Terrestrial Exposure Assessment

Nongranular applications: 

The terrestrial exposure assessment is based on the methods of Hoerger and Kenaga (1972)

as modified by Fletcher et al. (1994). Terrestrial estimated environmental concentrations (EECs) for

nongranular formulations were derived from maximum application rates up to 4.0 lb ai/acre. 

Table 51: Estimated Environmental Concentrations on Avian and Mammalian Food Items

(ppm)

Food Items

EEC (ppm) Max.

Residue

EEC (ppm)

Mean Residue

1 lb

ai/acre

4 lb

ai/acre

1 lb

ai/acre

4 lb

ai/acre

Short grass 240 960 85 340

Tall grass 110 440 36 144
Table 51: Estimated Environmental Concentrations on Avian and Mammalian Food Items

(ppm)

Food Items

EEC (ppm) Max.

Residue

EEC (ppm)

Mean Residue

1 lb

ai/acre

4 lb

ai/acre

1 lb

ai/acre

4 lb

ai/acre

138

Broadleaf plants and small insects 135 540 45 180

Fruits, pods, seeds, and large insects 15 60 7 28

Granular applications:

EECs for broadcast granular applications are calculated on the basis of mass (in mg) per area

(square foot), corrected for the fraction of the pesticide left on the surface. For unincorporated

broadcast applications, the entire fraction of the pesticide is assumed to remain on the surface. The

label for granular formulation prescribes adjusting the desired application rate by the fraction: band

width (inches) / row spacing (inches).

6. Ground Water Monitoring Data

The following studies provided ground water monitoring data that were used to develop the

water resource and aquatic exposure assessments for alachlor.

a. Introduction

Ground-water monitoring data collected, since 1991, by the USGS and the Acetochlor

Registration Partnership (ARP) have found alachlor parent in two to eight percent of ground-water

wells sampled. Up to 1.5 percent of these wells were found to have alachlor residues above the MCL

of 2.0 μg/L. These recent monitoring data are in agreement with earlier studies, such as those

reported in Pesticides in Ground Water Data. The maximum and minimum alachlor concentrations

were 15.89 μg/L and 0.05 μg/L, respectively. 

Monitoring data collected by the USGS (Kolpin and Goolsby, 1995; Kolpin et al., 1995;

Kolpin et al., 1996) also indicates that in addition to alachlor, more than 40 percent of the wells

sampled in Midcontinental US were contaminated with alachlor ESA degradate and/or 16 percent

were contaminated with the alachlor 2,6-diethylaniline degradate. There are no ground water

monitoring data on the other two major degradates (alachlor oxanilic acid and sulfinylacetic acid).

These results correspond with the fate data, which indicate that these alachlor degradates are more

mobile and persistent than the parent compound. 

These recent studies reflect that current alachlor use may still result in ground water

concentrations which exceed the LOCs for alachlor parent as detections have occurred which exceed
139

the current MCL of 2.0 μg/L. Since a much greater proportion of ground water wells are impacted

by alachlor degradates, if an MCL or cancer risk level is established for alachlor ESA at the same

level as alachlor parent, concern would be much greater than for the parent compound only. 

Similar chemicals, acetochlor, metolachlor, and propachlor, have also been found in ground

water. Approximately, the same percentage of wells have been found to be contaminated by

propachlor (1.2%) as alachlor (1.8%), although many fewer wells have been analyzed for propachlor.

Although the number of wells sampled for metolachlor and alachlor are similar, there are

approximately twice as many wells with detections of alachlor (1.8%) residues then metolachlor

(0.96%). Acetochlor, with a maximum of 2.17 μg/L, was detected in eight wells (4.6%) of 173 in

the registrant's ground-water monitoring study.

Detections of alachlor degradates in ground water are important because ground water may

represent an important means of exposure. Four major degradates have been identified for alachlor:

alachlor DM oxanilic acid, alachlor sulfinylacetic, alachlor sulfonic acid (ESA), and alachlor oxanilic

acid. As noted above, the four degradates are more persistent than the parent compound. Batch

equilibrium studies were previously requested on the degradates to assess their mobility. The

registrant has proposed using adsorption data from two propachlor degradates as surrogate data for

the alachlor degradates. This is acceptable for two degradates, but will still require the determination

of the mobility for the alachlor ESA degradate. 

b. Recent Groundwater Monitoring Data

USGS Midcontinent Ground Water Monitoring Studies:

In 1991, the USGS sampled 303 wells from a reconnaissance well monitoring network in

near-surface aquifers distributed across 12 Midwestern states. (Kolpin et. al., 1995) These wells

were distributed geographically and hydrogeologically by state, aquifer class (unconsolidated vs

bedrock), and relative depth. At least 25% of the land within a 3.2 km radius of the well was in corn

or soybean production during the 1990 growing season. One hundred wells were resampled during

1992 by selecting wells using a stratified random design based upon State and aquifer class.

The USGS found that five of the six most frequently detected pesticide compounds detected

in ground water of 12 Midwestern states were pesticide metabolites. Kolpin et. al. (1996) also

demonstrated that as the analytical reporting limits are decreased, there is an increase in the

differences in frequencies of detections. Alachlor ESA is reported almost 10 times more frequently

than parent alachlor at the 0.05 μg/L level.

Alachlor was detected in 6 wells (2%) out of 303 wells in 1991 and 5 wells (5%) out of 100

wells in 1992 in near-surface aquifers in 12 Midwestern states (Kolpin et. al., 1995). The alachlor

reporting limits were 0.05 and 0.002 μg/L for 1991 and 1992, respectively. Alachlor ESA was the

most frequently detected compound in 1992. It was found in 33 wells (45%) of 73 wells for which

the degradates were analyzed, with a reporting limit of 0.10 μg/L. In the same study, metolachlor
140

was detected in 12 wells (4%) out of 303 in 1991; and, 11 wells (11%) out of 100 in 1992, with the

same reporting limits as stated for alachlor. 

Additional samples were collected in 1993 (110 wells) and 1994 (38 wells) from

unconsolidated aquifers (Kolpin et al., 1996). Alachlor was detected in 10 wells (3.3%) out of 303

wells. Alachlor parent was found in 5.9% of the 153 wells for which metabolites were analyzed. The

maximum alachlor concentration detected was 4.27 μg/L, with a reporting limit of 0.05 μg/L.

Alachlor ESA was found in 70 wells (45.3%) of 153 wells analyzed for degradates. The maximum

concentration of alachlor ESA was 8.63 μg/L, with a 0.10 μg/L reporting limit. A second alachlor

degradate, 2,6-diethylaniline, was also detected in 15 wells (16%) of 94 wells analyzed. The

maximum concentration was 0.02 μg/L with a reporting limit of 0.003 μg/L.

 

Atrazine degradates deisopropylatrazine (10% of 303 well; maximum concentration of 1.17

μg/L) and deethylatrazine (22.8% of 303 wells; maximum concentration 2.20 μg/L) were also

detected. Metolachlor was also detected at levels above 0.05 μg/L in 8 wells (2.7%) out of 300

(Goolsby et. al., 1995).

Table 52: Summary of Wells with Detections of Alachlor ESA

Study Number of Wells Concentrations (μg/L)

Sampled Detected Percent

Detected

Maximum

Concentration

Reporting

Limit

USGS 1992 73 33 45% - 0.1

USGS 1993 153 70 45.3% 8.63 0.1

USGS 1994 38 25 65.8% 8.6 0.1

USGS-IOWA

1995

106 69 65.1% 14.78 0.1

Wisconsin 1993

vulnerable wells

293 206 70% 26.7

(ave. = 4.89)

1.01

1

 Analyzed by immunoassay

Acetochlor Registration Partnership Ground Water Monitoring Program (ARP-GWMP): 

As a requirement for the registration of acetochlor, the two acetochlor registrants are

conducting a ground-water monitoring program in seven major use states. Analytes are parent (no

degradates) alachlor, acetochlor, atrazine, dimethenamid, and metolachlor (only the first three were

reported). Ground-water samples are collected monthly from 175 wells located in corn producing

areas. The annual report from the first year of monitoring (only for acetochlor, alachlor, and atrazine)
141

covers the 13-month period, from December 1994 to December 1995. The limits of detection and

quantification for all analytes are 0.03 μg/L and 0.05 μg/L, respectively. 

The text of the annual report indicates that alachlor was detected in 45 samples (2.6%) out

of 1720 (27 of which were greater than 0.1 μg/L). Acetochlor residues were detected in 25 of 1720

samples (15 of which were greater than 0.1 μg/L) and atrazine was detected in 651 samples (427

were greater than 0.1 μg/L) out of 1720.

Results for the three pesticides are summarized in Table 53 below. Fourteen of the wells had

alachlor detects greater than limit of quantification (LOQ - 0.05 μg/L), six wells had detections of

acetochlor above the LOQ, and 75 wells had atrazine detections above the LOQ. Twenty-seven wells

had alachlor detections above the limit of detection (LOD) of 0.03 μg/L, 93 wells had detections of

atrazine above the LOD, and eight wells had acetochlor levels above the LOD.

Two of the fourteen wells with alachlor detections had detections on more than one sampling

date. One of these wells was located in Illinois. The first detection of alachlor for this well (May

1995) was also the greatest (13.05 μg/L) concentration. Alachlor concentrations in this well declined

with time, reaching 0.42 μg/L by December 1995. The second well with multiple detections was

located in Kansas. The first detection (0.3 μg/L) was reported in March 1995. The highest

detections for this well occurred in May 1995 (14.17 μg/L) and June (15.89 μg/L) and then generally

declined, reaching 3.64 μg/L by December 1995. Seven other wells also had alachlor detections in

March 1995. According to the registrant, these detections in Kansas and Illinois are linked to surface

runoff and ponding near the wellhead rather than leaching. New wells were installed, and follow up

sampling indicates that the underlying aquifers are not contaminated with alachlor.

Table 53: Detections and Concentrations (in μg/L) of Acetochlor, Alachlor, and Atrazine in

Study Conducted by the Registrants of Acetochlor.

Statistic Acetochlor Alachlor Atrazine

Number of Samples with

Detects $0.05 μg/L (% of

samples)

18 (1.0) 30 (1.7) 539 (31.3)

Number of Wells

(% of 173)

8 (4.6%) 14 (8.1%) 75 (43.4%)

Number of Samples11720 1720 1720

Mean 0.39 3.38 0.75

Standard Deviation 0.52 4.89 5.88

Minimum 0.06 0.05 0.05

1st Quartile 0.11 0.12 0.11
Table 53: Detections and Concentrations (in μg/L) of Acetochlor, Alachlor, and Atrazine in

Study Conducted by the Registrants of Acetochlor.

Statistic Acetochlor Alachlor Atrazine

142

Median 0.25 0.73 0.24

3rd Quartile 0.38 5.06 0.56

Maximum 2.17 15.89 131.532

1

It was not possible to determine whether data identified as missing were no data or below

detection limit.

2 The next highest value for atrazine was 30.03 μg/L.

Alachlor, Metolachlor and Propachlor in the Pesticides in Ground Water Data Base:

 

The Pesticides in Ground Water Data Base (PGWDB) (USEPA, 1992) reports that alachlor

was detected in 25 states, in 467 wells of 25933 sampled (1.8%). Of the wells with detections 99

wells (0.4%) had concentrations above the MCL. The PGWDB reported propachlor detections in

33 (1.2%) wells [in five states] out of 2718 wells sampled in eleven states. The concentrations ranged

from 0.02 to 3.5 μg/L, thus the maximum concentration exceeded the MCL of alachlor (2 μg/L), but

not the Lifetime Health Advisory (HAL) for propachlor (90 μg/L). 

The PGWDB also summarizes a number of studies which included metolachlor. Metolachlor

has been analyzed for in 29 states and detected in 20 states. Detections occurred in 213 (1%) wells

out of 22,255 wells sampled, with concentrations ranging from 0.02 to 157 μg/L. Three exceeded

the lifetime Health Advisory (LHA) of 70 μg/L for metolachlor, but typically appear to less than 10

μg/L.

Table 54: Summary of Alachlor, Metolachlor, and Propachlor Ground Water Monitoring Data

from the Pesticides in Ground Water Data Base

Detection

Information

Alachlor Metolachlor Propachlor

Number of Wells (Percent of Wells)

MCL or HAL (μg/L) 2 70 90

$ MCL 99 (0.38) 3 (0.01) 0 (0.00)

< MCL 368(1.42) 210(0.94) 33(1.21)

Total Detections 467(1.80) 213(0.96) 33(1.21)

Total Sampled 25993 22255 2718
Table 54: Summary of Alachlor, Metolachlor, and Propachlor Ground Water Monitoring Data

from the Pesticides in Ground Water Data Base

Detection

Information

Alachlor Metolachlor Propachlor

Number of Wells (Percent of Wells)

143

Number States with

detections

 25 20 5

Number of States with

monitoring

35 29 11

Range of concentrations

(μg/L)

trace to 3000 0.001 to 157 0.02 to 3.5

National Pesticide Survey (NPS):

The EPA National Pesticide Survey (USEPA, 1990) was conducted to provide a statistical

estimate of the frequency and concentration of pesticide contamination of drinking water wells in the

United States. From April 1988 to February 1990, EPA collected water samples and well information

from over 1300 community water systems and rural domestic drinking water wells. Based on these

data, EPA estimated that alachlor contamination occurred at or above the detection limit in about

3,140 (0.03 percent) of rural domestic wells nationwide. The detection limit for alachlor was 0.5

μg/L which likely resulted in the lower frequency of detection reported for alachlor compared with

other studies. Alachlor was not found in samples collected from community water supply wells.

Also, degradates of alachlor were not analyzed in the NPS.

National Alachlor Well Water Survey (NAWWS):

From 1987 - 1990, at the request of the EPA, Monsanto conducted the National Alachlor

Well Water Survey (NAWWS), a large-scale retrospective monitoring study patterned after EPA's

National Pesticide Survey of drinking water wells. (MRID Nos. 41400001, 41400002, 41400003,

41400004) This study was statistically designed to estimate the proportion of rural domestic wells

in alachlor use areas with detectable concentrations of alachlor (Holden et al., 1990, 1992).

Monsanto also chose to include atrazine, cyanazine, metolachlor, and simazine as analytes in the

NAWWS. The limit of detection for most chemicals (including alachlor) was approximately 0.03

μg/L. No degradates were analyzed in this study.

Wells selected for the NAWWS study were located in the rural portion of 89 counties, in 26

states where alachlor was used in 1986. Wells were selected based on county-level sales information

and vulnerability estimates in counties where corn, soybeans or peanuts were grown. A total of 1430

private rural wells were sampled. Alachlor was estimated to have been used within a half-mile of 58.8

percent of the wells during the last five years. Hydrogeologic characteristics of the aquifers sampled
144

were not directly measured; however, the probability that a well was installed in a confined (less

vulnerable) or unconfined (more vulnerable) aquifer was estimated by Monsanto. Nearly one-third

of the wells sampled were estimated to tap surficial, "vulnerable" aquifers. Over one-half of the wells

were located within 300 feet of surface-water sources (e.g. streams or ponds).

Alachlor detections were reported in nearly one percent of the wells sampled in the NAWWS

(Holden and Graham, 1992). Based on the monitoring results (summarized in Table 55), alachlor

was estimated to occur in 0.78 percent (46,800 wells) of the six million private, rural domestic wells

in the alachlor use area. Wells in the study area are estimated to supply drinking water to

approximately 20 million people. Alachlor was estimated to occur at levels exceeding the MCL of

2 μg/L in about 0.02 percent of private rural drinking water wells in the alachlor use area, or about

1,200 wells. 

Table 55: Estimated Percentage of Wells with Detections of Alachlor from the National

Alachlor Well Water Survey (NAWWS). 

Concentration (μg/L) Percentage of wells

with alachlor

estimated number

of wells1

standard error

(percent of wells)

>0.03 0.78 46,800 0.29

0.1 0.36 22,000 0.22

0.2 0.32 19,000 0.20

0.5 0.06 3,600 0.03

1.0 0.03 1,800 0.02

> 2.0 0.02 1,200 -

1

 estimated by EPA, based on total rural domestic water wells in the alachlor use area (6,000,000

wells).

USGS Ground Water Study in IOWA (1995):

The USGS, University of Iowa Hygienic Laboratory, and the Iowa Department of Natural

Resources have been involved in a joint program to monitor municipal wells in Iowa since 1982,

known as the Iowa Ground Water Monitoring Program (IGWM). In the summer of 1995, the USGS

sampled 106 municipal wells, representing the major aquifer systems in the state in order to determine

the occurrence of selected herbicide compounds (Kolpin and Kalkhoff, 1996). All samples were

analyzed for alachlor and alachlor ESA, with a reporting limit of 0.05 μg/L for all analytes.

Alachlor was detected in 7.5 percent of wells in the network, with a maximum of 0.63 μg/L.

Alachlor ESA was the most frequently detected compound, found in 65.1 percent of wells, at a

maximum concentration of 14.78 μg/L. Consistent with other studies, alachlor ESA was detected
145

almost 9-times as frequently as parent alachlor. Factors found to influence the frequency of detection

of both parent and degradates were: well depth, water age, dissolved oxygen content, and aquifer

type. Both parent and degradates are found much more frequently in shallow wells (defined as #50

meters deep), in post-1953 age water, and under reducing conditions. Alluvial and bedrock/karst

aquifers had the most frequent incidence of pesticide detections in this study.

Wisconsin DATCP Alachlor Study:

Following the reports of alachlor ESA in ground water in Ohio in 1993, Wisconsin's

Department of Agriculture Trade and Consumer Protection (DATCP), with the assistance of

Monsanto, began testing monitoring wells and private water supply wells for alachlor ESA in the

summer of 1993. Results indicated that alachlor ESA was present in a large number of samples, and

it was decided to include alachlor ESA in a Wisconsin survey of private wells most at risk. Wells

were selected in an area of high alachlor use from wells that had previous detections of triazine

herbicides or high concentrations of nitrate. The program was designed to indicate whether or not

a problem existed with alachlor or alachlor ESA in wells most at risk. Alachlor was detected in 12

of the 293 samples (4 percent) at concentrations ranging from 0.21 - 6.91 μg/L. Alachlor ESA was

detected in 206 of 293 samples (70 percent) at concentrations ranging from 1.09 - 26.7 μg/L. In part

because of these results, the State of Wisconsin established an interim health advisory (20 ppb) and

is considering proceeding to establish an enforcement standard for alachlor ESA.

State of Florida Monitoring Program:

Prior to the ban on the use of alachlor in the State of Florida, Monsanto conducted a groundwater monitoring study for alachlor in conjunction with the Florida Department of Agriculture and

Consumer Services (FDACS). The main focus of this study was the monitoring of alachlor in open

hole bedrock wells in Jackson County, in northern Florida. After confirmed detections of alachlor

were reported in 13 of 100 wells, the sampling was expanded to include 310 wells in 10 counties. 

Alachlor was detected in 189 samples, from 46 (15 percent) of 310 wells during sampling

from July 1989 to May 1990. Reported concentrations ranged from trace levels to 135 μg/L in a well

in Levy county. This high concentration is above the child one-day health advisory for the chemical,

which is 100 ppb. Concentrations in that particular well above the 100 ppb level were still detected

after 18 months. This pattern (persistent high concentrations of alachlor) was observed in many wells

with lesser concentrations although still above the MCL. FDACS stated that although Jackson

County is underlain by karst limestone, these conditions were not found throughout the 10 county

area where alachlor was detected. The State of Florida does not consider the detections in this study

to be the result of point-source contamination.

State of New York- Suffolk County:

From 1990 to 1992, the Suffolk County Department of Health Services (SCDHS) analyzed

private wells near a plant nursery for alachlor residues. Alachlor was detected in 14 of the 63 wells,
146

11 of which had at least one detection equal to or greater than the 2.0 ppb MCL. The highest

concentration detected was 49 μg/L. Subsequent sampling of 92 wells near plant nurseries resulted

in a single detection of alachlor at 0.6 μg/L.

The SCDHS did not find any evidence to suspect point source contamination. In their

response to the 1996 draft, the registrant indicated that they suspect that point source contamination

may have occurred. It is indicated that subsequent monitoring has shown that levels in most wells

are dropping below the MCL.

State of North Carolina:

The University of North Carolina-Asheville Environmental Quality Institute (EQI) conducted

a study from 1989 to 1992 to gather information on the spatial distribution of pesticides in rural water

supply wells in eastern North Carolina (Maas et. al., 1995). Alachlor was one of eight chemicals

investigated, with a method detection limit of 0.13 μg/L. Samples were collected from 171 sites,

which corresponded to individual wells. Alachlor was detected at 8.8 percent of the 171 sites, with

concentration that ranged from 0.23 to 68 μg/L. Five of the detections were above the 2.0 ppb MCL.

Multiple samples were collected over approximately a year and a half. Results indicated that alachlor

contamination was not a seasonal phenomenon, but persists over longer periods of time in eastern

North Carolina. Two of three wells that were re-sampled maintained levels of alachlor above the

MCL for over a year. The third had an initial detection at 0.3 μg/L, declined to below the detection

limit a half year later, increasing again to above the MCL one year after the original sampling. 

The EQI study concluded that the majority of detections of alachlor encountered in the study

appeared to be the result of normal agricultural use. Only one of the wells was located near a

pesticide mixing area (within 100 feet).

The study authors reported that alachlor detection was not significantly related to distance

from pesticide mixing, storage and loading areas suggesting that the observed groundwater

contamination was not a result of point sources. The authors also found that alachlor was detected

in wells more frequently further from cropped fields, and that the compound was detected in areas

that had received no application for at least several years. These data were interpreted as showing

that the detected alachlor came from a great distance from the well or from applications in the distant

past. The authors concluded that well water contamination was not a seasonal phenomenon but

persists over time. 

The Interagency Study of the Impact of Pesticide Use on Groundwater in North Carolina was

conducted in 1991-1996 (Wade et. al., 1997). In phase I of this study 55 wells representing the

state’s major drinking water aquifers were sampled at least twice and analyzed for pesticides. No

attempt was made to select these wells where pesticides were known to have been used. In phase

II, 97 shallow monitoring wells were installed and sampled at least twice. Phase II wells were located

in areas believed to represent the highest risk, and were adjacent to or down gradient from areas of
147

pesticide application. When pesticides were detected in phase II wells additional sampling was done

from nearby domestic supply wells. Forty-six domestic supply wells were sampled in this phase. 

Alachlor was not detected in phase I or phase II wells. Alachlor was detected in two domestic

supply wells near phase II wells that had other pesticides detected. One of the wells with alachlor

was a “shallow bored well” located within an agricultural field and had been used to fill spray

equipment. Two other domestic wells within 0.5 miles did not have detectable pesticides. The other

well with alachlor detected was a “bored well of unknown depth” located 100 feet from corn field

on an adjacent farm. Alachlor was detected in this well at two separate sampling events at 9.2 ppb

and 5 ppb. Three other monitoring and domestic wells near this well did not have detectable alachlor.

Continued sampling following completion of the study by the North Carolina Department of

Agriculture has not detected additional alachlor groundwater contamination. However, the alachlor

degradation products, including alachlor ESA, have been detected in groundwater at concentrations

ranging up to 22 ppb. (H. Wade, Personal communication, 1998) 

c. Possible Concerns

Since the degradation of alachlor appears to be much slower in aquifers than in the soil root

zone and since alachlor ESA is reported more frequently than alachlor in ground water, (Kolpin et

al., 1996) concluded that the degradation of alachlor occurs prior to being transported to the aquifer.

They theorize that if alachlor degradation occurred after reaching the aquifer, the frequency of

detections of alachlor and alachlor ESA would be more similar. They also report that alachlor ESA

appears to be persistent in shallow aquifers, because 90 percent of the wells having alachlor ESA

concentrations exceeding 0.10 μg/L remained at that level during all subsequent samples (1-year time

interval). If an MCL or cancer risk level is established for alachlor ESA at the same level as alachlor

parent and because of the much higher percentages of wells having degradate detections, the concern

for the population being exposed to levels of alachlor exceeding levels of concern is much greater

than for the parent compound only. 

Irrigation appears to increase the probability of contaminating ground water. The frequency

of herbicide detection (35%) with irrigation within a radius of 3.2 km was greater than the frequency

of herbicide detections (19%) without irrigation (Kolpin and Goolsby, 1995). 

7. Surface Water Monitoring Data

The following studies provided surface water monitoring data that were used to develop the

water resources and aquatic exposure assessments for alachlor.

a. Introduction

Alachlor can contaminate surface water at application via spray drift. Substantial fractions of

applied alachlor could also be available for runoff for several weeks post-application. The relatively
148

low soil/water partitioning of alachlor indicates that most of alachlor runoff will occur via dissolution

in runoff water (as opposed to adsorption to eroding soil).

b. Surface Water Data

Acetochlor Registration Partnership Data for 1995-1996:

This study is the most extensive data on alachlor concentrations in finished surface drinking

water available to the Agency. (MRID No. 44592401) Samples were collected at 179 different sites

(drinking water utilities) in the following 12 states: Delaware, Illinois, Indiana, Iowa, Kansas,

Maryland, Minnesota, Missouri, Nebraska, Ohio, Pennsylvania, and Wisconsin. Samples were

collected approximately once every two weeks from April through early September. Two to three

additional samples were collected at most sites, one to two in the Fall and one in the Winter.

Unfiltered samples were analyzed for total alachlor.

A TWMC was estimated by the Agency for each monitoring site in the ARP. These sites

were then ranked from highest to lowest. Based on the reanalysis of data covering 1995 and 1996,

Table 56 provides maximum and 90th percentile (upper 10th percentile) concentrations (peak and

annual TWMC).

Table 56: Summary of 1995 and 1996 Alachlor Monitoring by the ARP

Statistic Calculation for a given

site

Summary Across Sites

Maximum Value

for any Site (μg/L)

Value Equaled/Exceeded

on 10% of Sites (μg/L)

Peak

Concentrations

Highest Value Observed

1995-1996, for any Site

4 0.63

Annual Time

Weighted Mean

Weighted Mean for

1995-1996, for any Site

(weight by time)

0.36 0.1

USGS 1989, 1994, and 1995 Midwestern Stream Reconnaissance Studies :

Since the data submitted by the Acetochlor Registration Partnership was for samples collected

at set intervals once every two weeks, it is probable that the data are generally substantially lower

than peak alachlor concentrations associated with post-application runoff events. Such peak alachlor

concentrations are probably more closely represented by post-application data collected by the USGS

in reconnaissance studies conducted on numerous Midwestern streams. The USGS (Goolsby and

Thurman, 1991; Goolsby, 1995; Goolsby, 1996) conducted reconnaissance surveys of numerous

Midwestern streams in 1989, 1994, and 1995 to determine post-application, and in some cases preapplication and Fall concentrations of various herbicides including alachlor. Pre-application samples
149

collected in 1989 and 1994 and Fall samples collected in 1989 had alachlor concentrations much less

than 1 μg/L, and generally below the detection limit of 0.05 μg/L.

Since post-application samples were generally collected during the first major runoff event

after application, the concentrations in those samples should more closely represent peak alachlor

concentrations. The maximum post-application alachlor concentrations for 1989, 1994, and 1995

were 51.3, 10.1, and 19.9 μg/L, respectively. The 90th percentile (upper 10th percentile) postapplication alachlor concentrations for 1989, 1994, and 1995 were 12, 6.5, and 2.0 μg/L,

respectively. The substantially lower concentrations in 1994/1995 than in 1989 may reflect reported

decreases in alachlor use. 

In 1989, a pre-application sample, a post-application sample, and a Fall sample were collected

from 48 of the sites. The maximum and 90th percentile (upper 10th percentile) annual TWMCs were

11.6 and 3.4 μg/L, respectively. Annual TWMCs based on 4 quarterly samples (as specified to

determine compliance with the Safe Drinking Water Act) probably would have been somewhat lower

(but not more than 25% lower). 

In 1994 and 1995, samples were analyzed for alachlor ESA as well as alachlor. Alachlor ESA

concentrations are much higher than alachlor. This also appears to be true in early spring even before

alachlor application. 

USGS 1991-1992 Study of 8 River Locations Mississippi River Basin:

The USGS (Coupe et. al., 1995) sampled 8 locations on rivers within the Mississippi Basin

from April 1991 through March-September 1992 (depending on location) and analyzed the samples

for numerous insecticides and herbicides including alachlor. Samples were collected twice per week

from May 6 to July 15 1991, once per every two weeks from November 1991 to February 1992, and

once per week at other times. The samples were filtered (0.7 μ) and analyzed for dissolved alachlor.

The maximum peak and 1991 annual time weighted mean concentrations over the 8 sites were 3.6

μg/L and 0.43 μg/L, respectively (both in the Platte River at Louisville, NE).

For three sites (with the highest 1991 alachlor concentrations) pre-application concentrations

of less than 0.1 ppb in early spring rapidly increased to several ppb during post-application runoff

events in May and June, then rapidly declined to background levels by mid-late summer. The White

River at the Hazelton, IN site was the only one of those three sites at which sampling was performed

far enough into 1992 to give a second set of alachlor peaks (1992) in addition to the 1991 set.

Alachlor concentrations in 1992 were lower than in 1991 at that site.

USGS 1992 Midwestern Reservoir Reconnaissance Study:

The USGS (Goolsby et. al., 1993) sampled each of 76 Midwestern reservoirs four times

during 1992 and analyzed them for various herbicide degradates and herbicides including alachlor and

alachlor ESA. Alachlor was detected above a detection limit of 0.05 μg/L in 36%, 48%, 26% and
150

16% of the samples collected in late April to mid-May, late June to early July, late August to early

September and late October to early November, respectively. Alachlor ESA was detected more

frequently (72, 79, 77, and 64%) and at higher concentrations than alachlor. The highest alachlor and

alachlor ESA concentrations were for samples collected in June or July of 1992. The maximum and

95th percentile alachlor concentrations for June-July over the 76 reservoirs appear to be between 5

and 10 μg/L. The maximum and 95th percentile alachlor ESA concentrations for June-July appear

to be between 10 and 20 μg/L. After June-July, alachlor concentrations appear to decrease more

substantially than alachlor ESA concentrations.

Missouri River Public Water Supplies Association 1990 Study:

The Missouri River Public Water Supplies Association (MRPWSA) sampled the raw water

of 8 surface water supplies within the Missouri River Basin. (Keck 1991) Samples were collected

daily May-July 1990. The maximum peak and May-July mean concentrations were 14.9 and 0.47

ug/L, respectively (both at Kansas City, MO). However, the second highest peak and May-July mean

concentrations were 2.9 and 0.29 μg/L, respectively.

State of Illinois 1986-1988 Study:

The State of Illinois (Moyer and Cross, 1990) collected 4-7 samples per year from each of

30 flowing surface water sites during 1986-1988 and analyzed the unfiltered samples for numerous

pesticides including alachlor. The maximum alachlor peaks over the 30 sites were 5.6, 8.5, and 18

ug/L for 1986, 1987, and 1988, respectively. The maximum alachlor annual TWMCs over the 30 sites

were 0.65, 0.76, and 2.0 μg/L for 1986, 1987, and 1988, respectively. The maximum three year

TWMC over the 30 sites was 0.81 μg/L.

The State of Illinois (Taylor, 1994) recently summarized pesticide data for surface water

samples collected from 34 stations from October 1, 1985, through February 15, 1994. Thirty of the

stations were the same ones discussed in the Moyer and Cross 1990 document, but the Taylor

summary represents a update to February 1992. A total of 1278 samples were analyzed for alachlor

at a detection limit of 0.05 μg/L. Apparently assuming non-detects were equal to the detection limit,

Illinois reported maximum, 95th percentile, 90th percentile, and mean total (unfiltered sample)

alachlor concentrations over the 34 sites and 9 years of 18 μg/L, 0.90 μg/L, 0.32 μg/L, and 0.065

μg/L respectively.

Monsanto 1986 Finished Surface Water Supply Study:

In 1986, Monsanto sampled 30 finished surface water supply systems approximately weekly

from April through August or September and analyzed the samples for 5 herbicides including

principally alachlor. (MRID No. 40265901) The community water systems sampled represented 4

combinations of Lasso ®(alachlor) use and average soil susceptibility to runoff (high use/high runoff,

low use/high runoff, high use/low runoff, low use/low runoff). The susceptibility to runoff was

estimated from the weighted average of hydrological classifications (A, B, C, D) of soils within the
151

drainage area. Of the 30 community water systems sampled, 13, 2, and 15 were classified as using

sources which drain areas with high, intermediate, and low susceptibility to runoff, respectively. The

maximum and 90th percentile (upper 10th percentile) peak alachlor concentrations over the 30

systems were 9.5 and approximately 6.0 μg/L, respectively. The maximum and 90th percentile (upper

10th percentile) alachlor annual TWMCs over the 30 systems were 1.1 and approximately 0.73 μg/L

respectively. 

Monsanto 1985 Finished Surface Water Supply Study:

In 1985, Monsanto had sampled 24 finished surface water supply systems different from the

ones sampled in 1986. (MRID No. 00158911) They also sampled raw water. Samples were

collected approximately weekly from April 1995 through August or September 1995 and analyzed

alachlor parent only. The community water systems sampled represented areas of high, medium and

low alachlor use. 

The maximum and 90th percentile (upper 10th percentile) peak alachlor concentrations in

finished water over the 30 systems were 12 and approximately 4.2 ug/L, respectively. The maximum

and 90th percentile (upper 10th percentile) alachlor annual TWMCs over the 30 systems were 1.5

and approximately 0.62 μg/L, respectively. 

Alachlor has a low soil/water partitioning coefficient. Therefore, the primary treatment

processes employed by most surface water drinking water supply systems are not expected to be

effective in removing it. 

USGS 1984-1985 Study on the Cedar River Basin, IA:

The USGS (Squillace and Engberg, 1988) collected samples at 6 locations within the Cedar

River Basin (5 along the Cedar River, and one along the Shell Rock River). Samples were collected

approximately monthly from May 1984 through September 1985 at the Floyd and Cedar Falls

sampling locations, and from May 1984 through November 1985 at the other 4 locations.

Two sets of samples were collected. One set was centrifuged for the determination of the

dissolved concentrations of herbicides. "Total recoverable" herbicide concentrations consisting of

both extractable adsorbed and dissolved herbicides were determined in the sample set not centrifuged.

The maximum peak and annual TWMC concentrations over the 12 site-years were 23 and 3.3

μg/L respectively. The next highest peak and annual TWMCs were 21 and 1.9 μg/L, respectively.

The maximum two year TWMC over the 6 sites was 1.7 μg/L.

Baker 1982-1985 Study on Ohio Tributaries to Lake Erie:

Baker collected samples at various times including several times per week from mid-April to

mid-August from 8 Ohio tributaries to Lake Erie during 1982-1985 and analyzed them for many
152

pesticides including alachlor. (MRID No. 41065205) Alachlor Peak and 4/15-8/15 TWMCs

concentrations were reported.

The maximum and 90th percentile (upper 10th percentile) peak alachlor concentrations over

the 30 site-years are 76 and 32 μg/L, respectively. The maximum and 90th percentile (upper 10th

percentile) 4/15-8/15 TWMCs over the 24 site-years are 3.3 and 2.7 μg/L, respectively.

Baker 1983-1987 Lake Erie Basin Case Study

The Water Quality Laboratory at Heidelberg College, Ohio (Baker et. al., 1991) sampled

seven Ohio streams and rivers of the Lake Erie Basin for a number commonly used herbicides and

insecticides, including alachlor. Samples were collected and analyzed at frequent intervals (daily)

during the pesticide use period mid-April to mid-August, especially during runoff producing storm

events, and twice per month during the remainder of each year’s cycle. Samples were collected at

existing USGS Gaging Stations. Alachlor was detected above the level of detection (0.1 ug) at all

sampling stations in all years during the study. Alachlor peak and time weighed mean concentrations

(TWMC) were reported.

The maximum peak concentration over the five-year study of 91.47 ug/L (n=410) occurred

in the smallest basin, Lost Creek. The maximum TWMC over the study period of 1.74 ug/L (n=534)

occurred in Honey Creek basin, the third smallest basin, but the second highest in agriculture

intensity.

Kirby-Smith 1987-1991 Study on the South River Estuary North Carolina:

In a study of effects of pesticides on marine and estuarine aquatic biota from farmland runoff,

alachlor was monitored in several headwater streams of the South River in the Pamlico Sound, North

Carolina. (MRID No. 441095503) Data collected during the conduct of this study provided

valuable information on the concentrations of alachlor in estuarine waters from known pesticide

applications.

Dissolved alachlor concentrations increased from background (residual) levels of

approximately 0.019 μg/L to a maximum of 48 μg/L following pesticide applications and significant

rainfall. Alachlor concentrations rapidly decreased to less than 1 μg/L following the termination of

pesticide applications and after several runoff producing rain events had occurred. Eventually,

concentrations returned to background level, although specific timing could not be determined from

the submitted study.

c. Possible Concerns over Alachlor and Alachlor ESA in Surface

Water

According to available data, the potential risks to fish and aquatic invertebrates posed by

alachlor in surface water are low. Potential risks to aquatic plants posed by alachlor are currently
153

being assessed by the Agency. The potential risks of alachlor ESA to fish, aquatic invertebrates and

aquatic plants has not been well characterized.

In analyzing surface water concentration data, the Agency considers the frequency that annual

averages exceed the drinking water MCL (for alachlor, 2 μg/L), and the frequency that peak

concentrations exceed the MCL by a factor of 4 or more: Compliance with the Safe Drinking Water

Act is based on comparison of the MCL to an arithmetic average of four quarterly measurements.

Consideration of 4 times the MCL (4MCL) is of interest because if one or more of four measurements

exceeds 4MCL, then the average of the measurements exceeds the MCL. 

Originally, most of the Agency’s concern over alachlor in drinking water was due to individual

alachlor measurements frequently exceeding 4 times the MCL. The frequency of exceedances of

4MCL was greatest in the 1989 USGS reconnaissance study in which samples were collected during

major runoff events following application, and in the study by Baker (1988), in which samples were

apparently collected at least 3 times a week and not time composited. They were less frequent in the

1994 and 1995 USGS reconnaissance studies (which were also designed to capture peak

concentrations) possibly due to decreases in alachlor use. 

With the exception of 2 site-years in the 1984-1985 USGS study of the Cedar River Basin and

one site-year in the 1986-1988 Illinois EPA study, none of the annual TWMCs for alachlor exceeded

the MCL of 2 μg/L. This includes the 1985-1986 Monsanto studies of drinking water supplies and

the recent 1995 Acetochlor Registration Partnership study of 175 sites over 12 states. In that study,

the maximum annual TWMC was 0.4 μg/L. Although the study used set sampling intervals that may

often miss peak concentrations associated with runoff events, the once every two weeks sampling

from April through September and the Fall and Winter samples (a total of 14/site) is much more than

the 4 quarterly samples required under the SDWA. Again, the relatively low alachlor concentrations

compared to some earlier studies may reflect substantial decreases in alachlor use.

8. Water Resource Assessment

a. Ground Water Assessment

Alachlor exhibits the properties associated with chemicals that are found in ground water.

The chemical has a high solubility and mobility in soils. Once the chemical reaches deeper soil layers

with lower organic matter content and lower microbial populations, it will persist. An independent

study conducted for EPA indicates that alachlor half-lives at different depths in a sandy loam and a

silt loam soil increased to about 250 to 600 days at a depth of 5 feet (Lavy et al., 1993). Alachlor

has been found to leach in the field at soil depths of up to 36- to 48-inches (the deepest layer

sampled). Considering the nature of the chemical (i.e., moderately persistent and very mobile in many

soils), there is a strong possibility of movement to ground water, especially in vulnerable areas. This

has been confirmed by a substantial number of detections reported in the "Pesticides in Ground Water

Database," and in the National Alachlor Well Water Survey conducted by the registrant, from which
154

EPA determined that alachlor residues have had a significant impact on ground-water quality

throughout the use area.

Several sources of information on monitoring/detections of alachlor and alachlor metabolites

in ground water are reviewed in this document. That information confirms that alachlor and alachlor

degradates will move into ground water. These monitoring data are summarized in Table 57.

Table 57: Summary of Wells with Detections of Alachlor (Parent).

Study Well type Number of Wells (%)

Sampled Alachlor

Detected

Concentration

<MCL

Concentration

$MCL

USGS

(1991-1994)

drinking 303 10 (3.3%) 9 (3.0%) 1 (0.3%)

ARP-GWMP monitoring 173 27

(15.6%)

25 (14.5%) 2 (1.2%)

PGWDB mixed, most

drinking

25933 467

(1.8%)

368 (1.4%) 99 (0.4%)

NPS drinking 1300 1 (<0.1%) 0 (0%) 1 (<0.1%)

NAWWS drinking 1430 28 (2.0%) 26 (1.8%) 2 (0.1%)

Florida drinking 310 46 (15%)

North Carolina drinking 171 15 (8.8%) 10 (5.9%) 5 (2.9%)

PGWDB = Pesticides in Ground Water Database, 

NPS = National Pesticide Survey; 

NAWWS = National Alachlor Water Well Survey, 

USGS = U.S. Geological Survey Midcontinent Study, 

ARP-GWMP = Acetochlor Registration Partnership Ground-Water Monitoring Program.

Persistence of Alachlor in Ground Water:

Ground-water monitoring studies have shown that alachlor contamination is common in use

areas. Recent data suggests that alachlor can persist in the subsurface for years and that ground water

contamination can be expected long after use has stopped. Maas et. al. (1995) found evidence that

low concentrations of alachlor in drinking water wells persisted over long periods, and contamination

can move off-site via transport in ground water. In Florida, significant alachlor contamination still

occurs years after all alachlor use was canceled in February 1991. Sixteen wells found to have

alachlor at concentrations greater than 2.0 ppb prior to the ban have been sampled yearly since 1991.

The mean alachlor concentrations in these wells have not changed over time (Simons and Fisher,

1997; R.E. Fisher, personal communication, 1998).
155

Alachlor Exposure from Drinking Ground Water:

Results of several studies designed to assess the occurrence of alachlor in drinking water wells

makes it possible to roughly estimate the number of people exposed to the compound by drinking

contaminated ground water. Based on U.S. Census data the National Ground Water Association

(NGWA) estimates that 53% of the American public relies on ground water for their drinking water.

This includes about 282,000 public supply wells and approximately 15.1 million households using

private wells. While there is little evidence of contamination in public supply wells a significant

number of private house hold wells will be contaminated. It is possible that a large number of people

in the U.S. can expect to be exposed to alachlor in their drinking water. Hundreds of thousands of

people living in households supplied by private wells will have alachlor and/or alachlor degradates

in their drinking water as a result of labeled use of the compound. Large numbers of Americans can

expect to have alachlor concentrations above the current Maximum Contamination Level (MCL) of

2.0 ppb in their drinking water as a result of labeled use of the compound. MCLs are established for

public drinking water supplies and are not enforceable for private water supplies. A one-time

detection above the MCL does not necessarily constitute a violation in public water systems or trigger

requirements for mitigation. Such actions are based on average annual concentrations, which is a

time-weighted average of all detections, including the exceedance value, for the entire year. Since

drinking water violations reported by EPA’s Office of Water are for public water supplies and are

based on average annual concentrations, the frequency of such exceedances is likely to be less than

the frequency of individual detections above the MCL reported here.

The National Alachlor Well Water Survey (MRID No. 41400001) was designed primarily to

assess the occurrence of alachlor in rural wells in high alachlor use areas. The study estimated 6

million wells, serving 20 million households, occurred in the alachlor use areas, based on Monsanto’s

1986 alachlor sales data. The majority of the wells were near agricultural areas, and 40% were within

300 feet of fields where alachlor target crops were grown. Alachlor was detected in 2.0 % (standard

error of 0.25) of sampled wells at measurable concentrations. The survey found 0.18 % (standard

error of 0.12) of the sampled wells had alachlor concentrations above 2.0 ppb. No significant

differences were seen in wells on farm and non-farm properties. Exposure estimates by Monsanto

(assuming a nonlinear distribution for detections, which is reasonable for pollutant data with

asymmetric distributions and a relatively low occurrence of events) suggest that more than 100,000

people in the study area had detectable levels of alachlor in their water supply, 35,000 would be

exposed to concentrations of > 0.2 ppb, and more then 3,000 people would have alachlor

concentrations above 2.0 ppb. Weaknesses in the survey include: (a) the NAWWS use area

underestimated the alachlor use area defined by Resources For the Future, (b) the study was

conducted in a relatively dry year (1988) which would have minimized the potential for leaching, and

(c) the estimates do not include small community wells that serve more than 15 households or more

than 25 people, which may underestimate the total number of people exposed to alachlor in drinking

water (Rappaport, ICF, 1991). 

Two studies in North Carolina examined levels of alachlor in drinking water wells (Maas et.

al., 1995; Wade et. al., 1997). NGWA estimates that North Carolina has 912,000 household wells
156

and 20,000 public and community supply wells. In eastern North Carolina, 8.8% of drinking water

wells sampled between 1989 and 1992 contained measurable alachlor concentrations and 2.9 % were

above the current MCL of 2.0 ppb (Maas et. al. 1995). This study also found that contamination is

not always confined to wells in or close to fields to which alachlor was applied. Results of the eastern

North Carolina study show a higher percentage of wells with alachlor contamination than that found

in the NAWWS study. This study, conducted primarily within the coastal plain, may reflect potential

exposure in an area in which the ground water is highly vulnerable to contamination from pesticides

(as delineated by Kellog et. al., 1992). 

Sampling in Florida found that 9.4 % of drinking water wells were contaminated with alachlor

and 5.5 % had alachlor concentrations above 2.0 ppb (Simons and Fisher, 1997). Most of the well

contamination at high levels may be a result of mixing and transfer operations or other point sources

(R.E. Fisher, personal communication, 1998), and the owners have been provided with water

treatment systems or an alternate supply. In Florida, about 794,500 households are served by private

wells; 16,000 are on public and community supply wells. Concerns about such exposure resulted

in a ban of the use of alachlor in Florida. Since the 1991 ban, average alachlor concentrations in wells

initially found to have levels above 2.0 ppb have not changed, and individual treatment systems are

still required to provide safe drinking water to these households. More than five years after alachlor

use was banned, these wells still show contamination.

Despite the large amount of uncertainty associated with exposure estimates, they provide an

indication of the magnitude of people who can expect to have alachlor in their drinking water. Tens

of millions of Americans rely on domestic wells for their drinking water and the majority of these are

in rural areas. Even if a few wells in any study show significant levels of alachlor contamination, or

only a few percent of wells are contaminated, this is suggestive of a large number of people being

exposed.

There are additional concerns related to contamination of ground water used for drinking

water supply. Alachlor appears to be persistent under aquifer biological and geochemical conditions.

This means that alachlor can appear in ground water years after use and can migrate with ground

water away from use areas. Alachlor contamination has resulted in loss of untreated ground water

as a source of drinking water in Florida and other states. Years after alachlor was banned, the

resource is still degraded.

b. Surface Water Assessment

Alachlor can contaminate surface water at application via spray drift. Substantial fractions

of applied alachlor could be available for runoff for several weeks post-application. The relatively

low soil/water partitioning of alachlor indicates that most runoff will occur via dissolution in runoff

water (as opposed to adsorption to eroding soil). The persistence of alachlor in surface waters with

high microbiological activities should be somewhat limited by its susceptibility to biodegradation.

Persistence will also be limited in waters with short hydrological residence times by flow out of the

system. However, its resistance to abiotic hydrolysis and direct aqueous photolysis, coupled with its
157

low volatilization potential should make alachlor more persistent in waters with low microbiological

activities and long hydrological residence times.

Alachlor may also enter freshwater, estuaries, and coastal marine water in areas of interaction

with ground water. Presence in fresh surface water of alachlor ESA before application suggests that

there has been input to rivers and streams from ground water.

There is an extensive body of information on levels of alachlor and alachlor degradates in

surface water. Table 58 summarizes the major surface water studies:

Table 58: Summary of Major Surface Water Sources with Alachlor Detections by Study.

Study Number of

Sites

Maximum Peak

(ug/L)

Maximum TWMC1

(ug/L)

ARP - 1995-1996 175-179 4.0 0.36

USGS - Midwestern

Stream Recon. 1989

48 51.3 11.6

USGS Mississippi River

Basin Study 1991-1992

8 3.6 0.43

State of Illinois 1986-

1988

30 18 0.81

Monsanto Finished

Surface Water Study

1986

30 9.5 1.1

Monsanto Finished

Surface Water Study

1985

30 12 1.5

USGS Cedar River Basin

Study 1984

6 23 1.7

Ohio Tributaries to Lake

Erie 1982-1985

8 76 3.32

Lake Erie Basin Case

Study 1983-1987

7 91.47 1.74

1TWMC: Time weighted mean concentrations, annual unless otherwise noted.

2

 Time weighted mean concentration calculated over a 4 month period of the study; April 15 to

August 15
158

The monitoring results primarily reflect residue detections in lotic waters, such as rivers and

streams, or large lentic bodies of water, such as man-made reservoirs and lakes. Therefore the levels

observed may have been affected by dilution, degradation, or adsorption to soil or sediment, relative

to edge-of-field levels (values occurring close to sites of application immediately following runoff

events). Edge-of-field levels may be better represented by modeling. (However, at this time only

screening level modeling has been undertaken.) Also, the model scenarios represent small, static

bodies of water. Reported peak concentrations are affected systematically by the intensity of

sampling: with less frequent sampling there is higher probability of levels in the environment that

substantially exceed the highest values detected.

Of the surface water monitoring data available, the USGS Midwestern Stream Reconnaissance

Studies (1989, 1994, 1995) give what are probably the values closest to the most extreme edge-offield levels. In that study peak exposures were 51.3 μg/L for 1989, 10.1 μg/L for 1994, and 19.9

μg/L for 1995. The 90th percentile values (upper 10th percentile values) were 12, 6.5, and 2.0 μg/L

for the same years.

c. Alachlor Degradates in Water

The major degradates of alachlor are alachlor DM-oxanilic acid, alachlor oxanilic acid,

alachlor sulfinylacetic acid, and alachlor ethane sulfonic acid (alachlor ESA). While uncertainty exists

concerning the environmental or health effects of these breakdown products, available data suggest

that the degradates are more persistent and mobile than parent alachlor. Limited monitoring data

suggest that alachlor ESA is often found in ground water wells 5-10 times more frequently then the

parent compound. Alachlor ESA has been detected frequently in Midwestern reservoirs and streams

at concentrations much greater than alachlor. High concentrations of alachlor ESA in flowing water

even in early spring, before alachlor application, may reflect discharges from ground water. The

major degradates may be available for runoff longer than alachlor, and will probably be transported

primarily by dissolution in runoff water. The degradates will probably readily partition into the water

column and in addition to alachlor ESA, other degradates may also be more persistent in surface

water than alachlor.

9. Aquatic Exposure Assessment

Preliminary aquatic EECs are estimated using GENEEC (GENeric Expected Environmental

Concentration), a screening model that provides an upper-bound estimate of EECs on a high

exposure site. The GENEEC program uses basic environmental fate values (adsorption to soil,

degradation in soil before runoff and in water) and pesticide label information (rates, intervals,

incorporation, method of application) to estimate the EECs in a one-hectare, two-meter deep pond

following the treatment of a 10 hectare field. The runoff event occurs two days after the last

application. The model accounts for direct deposition of spray drift onto the water body (assuming

5% of the application rate for aerial spray applications and 1% for ground spray applications). Some

of the input parameters used for the alachlor GENEEC runs are listed in Table 59.
159

Table 59: Environmental Fate Parameters used to Predict Alachlor EECs

Parameter Value

water solubility (ppm) 242 ppm

Koc 190

aerobic soil metabolism, t1/2 21 days1

hydrolysis t1/2, pH 7 Stable

aerobic aquatic metabolism, t1/2 175 days

aqueous photolysis t1/2 80 days

1The aerobic soil metabolism half-lives in three studies was 6-21 days.

 GENEEC modeling was performed for a range of use scenarios based on combinations of

application rate (1-6 lb ai/acre) that were on the label at the time the modeling was performed.

Ground spray and granular applications were evaluated along with the effects of incorporation. In

addition to scenarios involving a single application, a scenario was evaluated with two 2 applications

of 2 lb ai/acre by ground spray without incorporation, separated by 30 days. On June 30, 1998, new

labels were accepted by the Agency in which the maximum single application rate is 4 lb ai/acre.

Thus, the 6 lb ai/acre rates were eliminated from this discussion.

Peak EECs (representing concentration immediately following runoff) ranged from 33 ppb

for 1 lb ai/A to 133 ppb for 4 lb ai/A. The 56-day average EECs ranged from ranged from 27.4 ppb

to 110 ppb for the same range of application rates.

Table 60: Alachlor Screening Level Aquatic EECs Generated by GENEEC

Application

Rate/Method/Incorporation

EEC Estimates Over Time (ppb)

Peak 4 Days 21 Days 56 Days

1.0lb Granular/Ground/none 33 32.7 30.7 27.4

2.0lb Granular/Ground/none 66.3 65.5 61.5 58.9

4.0lb Granular/Ground/none 133 131 123 110

1.25lb ai/groundspray/none 39 38 36 32

2.5lb ai/groundspray/none 78 77 72 65

3.0 lb ai/groundspray/none 94 93 87 78
Table 60: Alachlor Screening Level Aquatic EECs Generated by GENEEC

Application

Rate/Method/Incorporation

EEC Estimates Over Time (ppb)

Peak 4 Days 21 Days 56 Days

160

4.0lb ai/groundspray/none 125 124 116 104

4.0 lb ai/groundspray/2.0 inch

incorporation

64 63 59 53

2.0 lb ai/A twice

groundspray/no incorp./30 day interval

92 91 85 76

For comparison, of the surface water monitoring data available, the USGS Midwestern

Stream Reconnaissance Studies (1989, 1994, 1995) give what are probably the closest values to peak

exposures occurring close to application sites soon after application. Peak exposures were 51.3 μg/L

for 1989, 10.1 μg/L for 1994, and 19.9 μg/L for 1995. The 90 th percentiles (upper 10th percentiles)

were 12, 6.5, and 2.0 μg/L for the same years.

The Agency has reviewed an extensive body of information on levels of alachlor and alachlor

degradates in surface water. This database for alachlor is substantially greater than that available for

most pesticides. These monitoring results primarily reflect residue detections in lotic waters such as

rivers and streams or large lentic bodies of water such as man-made reservoirs and lakes. As such

the data are good indications of what residue levels might be expected after residues have traveled

farther down the watershed. These residue detections are influenced by a number of factors including

dilution by the respective waterbody, time of monitoring, position of monitoring stations, and the

number of measurement samples recorded over time (when averaging sample detection levels). Thus,

this information should be used as an indication of levels which might be expected after dilution,

organic degradation, and soil or sediment adsorption factors have acted on the chemical for the period

of time between application and actual sampling at respective monitoring stations. In many cases,

peak concentrations of alachlor occur during early to late spring months when rainfall events lead to

higher than average runoff. Simple averages of measured concentrations are biased towards

representing those time periods with more samples, a bias that can be eliminated by using TWMCs.

An additional limitation of the monitoring information is the likelihood that some actual

environmental concentrations will exceed the highest levels detected. The chance that a peak

concentration will not be detected is expected to differ among monitoring studies, depending on the

frequency of sampling and on the variability of environmental concentrations.

Tables 61 and 62 summarize two studies, one conducted by the US Geological Survey in 1991

and one conducted by the State of Illinois in 1990. 
161

Table 61: USGS Mississippi River Basin Survey, 1991-19921

Location Sampled 

(24 Samples per location)

Alachlor Concentration (μg/L)

Peak Arithmetic

average

Annual

TWMC

White River, Hazelton, In. 3.2 0.3 0.22

Ohio River, Grain Chain, Il. 0.40 0.08 0.07

Miss. River, near Clinton, IA. 0.85 0.16 0.10

Illinois River, Valley City, Il 3.00 0.40 0.22

Platte River, Louisville, NE 3.60 0.43 0.22

Missouri River, Hermann, Mo. 0.92 0.19 0.12

Miss. River, near Thebes, Il. 0.86 0.27 0.23

Miss. River, Baton Rouge, LA. 0.46 0.12 0.09

1Based on bi-weekly samples May to August and weekly samples Sept. to Dec. 1 (Coupe et. al.,

1995).

Table 62: Illinois Surface Water Survey, 1986-19881

Site Type

Alachlor Concentration as a Range (over sites

and years) (ug/L) 

Range of Peak values Range of annual

TWMC

Illinois Rivers (21 Sites-18 Rivers) 0.02- 8.5 0.02-0.65

Illinois Creeks (9 Creeks) 0.02-18.0 0.02-2.0

1

 Based on samples from 30 sites representing different streams and rivers, 4-7 samples per yr at each

site (Moyer and Cross, 1990).

In addition to surface water data reviewed by the Agency, the following data (see Table 63)

is reported by the Chesapeake Bay Fall Line Toxics Monitoring Program, representing the period

from March 1992 to February 1993. Monitoring data is based on one station per river. This data has

not been reviewed by the Agency. At this time it is viewed as supplementary information that tends

to confirm concerns for adverse effects on aquatic organisms. Also, the study represents an East

Coast tributary and thus provides a wider geographical scope for the monitoring data.
162

Table 63: Summary of Chesapeake Bay Fall Line Toxics Monitoring

Program for Alachlor Detections in Major Streams.

Location Range detected

μg/L

Mean

μg/L

Susquehanna River <2.05-23.1 4.4

Potomac River 2.5-20.9 4.1

James River 7.5-20.2 2.9

10. Comparative Assessment with Other Acetanilides

a. Environmental Fate Characteristics

Alachlor, acetochlor and metolachlor are moderately persistent while propachlor appears to

be the least persistent of all the acetanilides. However, the available aerobic soil metabolism values

(t1⁄2 and DT50) for the four chemicals are within the same order of magnitude. All of the compounds

are highly mobile.

An inspection of the physico-chemical characteristics of these chemicals reveals that alachlor

has the second lowest molecular weight. Alachlor has a high solubility in water, although it is lower

than the solubility of acetochlor and metolachlor. All the compounds have relatively low

octanol/water partition coefficients, low vapor pressures, low calculated Henry’s Law constants, and

relatively low bioaccumulation factors.

Further investigation of the environmental fate characteristics reveals that all four chemicals

are relatively stable to hydrolysis and photolysis in water. Three of the compounds are stable to

photolysis on soil while metolachlor has a half-life of 8 days. In general, it appears that the important

routes of dissipation for these compounds are aerobic soil metabolism and leaching. The aerobic soil

metabolism 50% dissipation rates range from 2.7 days for propachlor, to 2-3 weeks for alachlor, and

67 days for metolachlor. The available studies indicate that anaerobic soil metabolism is not an

important route of degradation for the acetanilides.

The half-lives observed in the field are of the same order of magnitude of the half-lives of

aerobic soil metabolism studies in all cases. Results of the field studies confirm aerobic soil

metabolism as an important route of dissipation for the four compounds.

b. Ecotoxicity

The comparative analysis of the ecotoxicity data for propachlor, alachlor, acetochlor, and

metolachlor is based on data taken from the OPP/EFED Pesticide Ecotoxicity Data Base-1997. Only
163

those studies classified as Core data were used in the analysis. Category terminology was taken

directly from Brooks, et al. (1973).

Table 64 summarizes the environmental fate characteristics of the four acetanilides. Tables

65 through 71 show the ecological toxicity data available for birds, mammals, freshwater fish,

estuarine fish, freshwater aquatic invertebrates, and estuarine invertebrates. The analysis suggests

that this group of acetanilides are similar in toxicity. Propachlor appears to be more toxic to fish and

aquatic invertebrates while acetochlor is more toxic to birds. However, no clear differences are

evident.

Avian Species

On an acute oral basis, the toxicity data suggest that acetochlor is the most toxic of the four

herbicides (49 mg/kg), followed in order by propachlor, alachlor and metolachlor. The avian

subacute dietary data suggest that acetochlor is slightly more toxic (4171 ppm) than the other three

herbicides. In general, both the acute and subacute avian toxicity data indicate that all four herbicides

are practically non-toxic to slightly toxic to avian species on both an acute and subacute basis. These

data suggest a low risk to most avian species from either acute or subacute exposure from the use

of these four herbicides.

Mammalian Species

No mammalian toxicity data are available for alachlor. Available toxicity data suggest that

propachlor is practically nontoxic while acetochlor and metolachlor are moderately toxic to

mammalian species.

Fish Species

The 96-hour LC50 values generally indicate that propachlor is highly toxic while alachlor,

acetochlor and metolachlor are moderately toxic to freshwater fish species. Available toxicity data

for alachlor, acetochlor and metolachlor suggest that these herbicides are only moderately toxic to

estuarine fish species.

Aquatic Invertebrates

The freshwater aquatic invertebrate 48-hour LC50/EC50 data suggest that propachlor is the

most toxic (0.79 ppm) of the four herbicides, ranging from moderately to highly toxic to freshwater

invertebrates. The 48-hour LC50 values generally indicate that alachlor, acetochlor and metolachlor

are moderately to slightly toxic to freshwater invertebrate species. Available toxicity data for

alachlor, acetochlor and metolachlor indicate that these herbicides are only moderately toxic to

estuarine invertebrate species.
164

c. Comparative Assessment Tables for the Acetanilides Alachlor,

Acetochlor, Metolachlor, and Propachlor

The following Tables provide a comparison of environmental fate and ecological toxicity data

for the acetanilides alachlor, acetochlor, metolachlor, and propachlor. 
165

Table 64: Comparison of the Environmental Fate Characteristics of Alachlor, Acetochlor, Metolachlor, and Propachlor:

Characteristic Alachlor Acetochlor Metolachlor Propachlor

Chemical Structure

Empirical Formula C14H20NO2Cl C14H20NO2Cl C15H22NO2Cl C11H14NOCl

Molecular Weight 269.80 269.80 283.80 211.69

Vapor Pressure (mm Hg) 2.2x10-5 4.40x10-5 1.30x10-5 7.90x10-5

Log KOW 2.64 3.0 2.30

Henry's Constant (atm

m3/mol)

3.2x10-8 7.0x10-8 9.16x10-9 3.59x10-8

Solubility in water (ppm) 240 223 530 613

Hydrolysis Stable at pH 3.0, 6.0, and

9.0

Stable at pH 5.0, 7.0, 9.0 Stable at pH 5.0, 7.0, 9.0 Stable at pH 5.0, 7.0, 9.0

Photolysis in Water Not expected to be an

important route of

degradation, based on

UV absorption spectrum

Stable 70 days Stable

Photolysis on soil Not expected to be an

important route of

degradation, based on

UV absorption spectrum

Stable 8 days Not an important route of

degradation

Aerobic Soil Metabolism 2-3 weeks in three soil

types

8-14 days

one study reports 110 days

67 days 2.7 days
Table 64: Comparison of the Environmental Fate Characteristics of Alachlor, Acetochlor, Metolachlor, and Propachlor:

Characteristic Alachlor Acetochlor Metolachlor Propachlor

166

Anaerobic Soil Metabolism Not available 230 days in sandy loam

soil

81 days 146 days in a clay-loam

sediment/lake water

system

Mobility Very mobile in loamy

sand, silt and sand,

mobile in silt loam in

column leaching studies

Estimated KOC=190

Kd variable between 0.81-

7.5

Kd between 0.08 and 4.81 Propachlor Kads=0.45-

1.39; KOC=73-138, in

loamy sand, sandy loam,

loam, silty clay loam.

Propachlor oxanilic acid

Kads=0.03-0.08, KOC=391-

3428. 

Propachlor sulfonic acid

Kads=0.03-0.07,

KOC=47-624

Terrestrial Field Dissipation 11 days in Chico,

California

8-36 days at 5 sites in the

United States

Supplemental studies

show variability between 7

and 292 days

1.0-1.7 days in Janesville,

Iowa; 5.0-5.8 in York,

Nebraska; 2.3-2.8 in

Uvalde, Texas

Bioaccumulation in Fish Not expected to be

important, based on KOW. 

In a supple-mental study

BCF=5.8X in fillet,

BCF=11X in whole, and

BCF=15X in viscera

BCF=40X edible

BCF=780X non-edible

BCF=150X whole fish

BCF=15X edible

BCF=69X whole fish

BCF=13X edible

BCF=71X nonedible

BCF=37X whole fish

The above table shows that alachlor, acetochlor, metolachlor, and propachlor are not only structurally related, but they also exhibit similar fate properties.
167

Table 65: Comparison of Avian Acute Oral LD50 data (mg/kg) for Propachlor, Acetochlor, Alachlor and Metolachlor

Chemical Avian 

LD50 (mg/kg)

Category MRID No. Classification

Propachlor 88 Moderately toxic 00132907 Core

Alachlor 1499 Slightly toxic 00079523 Core

>2000 Slightly toxic 00160000 Core

>2610 Slightly toxic 00107908 Core

Acetochlor 49 Highly toxic 41963303 Core

1567 Slightly toxic 00079598 Core

1788 Slightly toxic 41565129 Core

Metolachlor 4640 Slightly toxic 00015547 Core

* Technical Grade Material
168

Table 66: Comparison of Avian Subacute Dietary LC50 data (ppm) for Propachlor, Acetochlor,

Alachlor and Metolachlor

Chemical Avian LC50 Category MRID No. Classification

Propachlor >5000 Practically Non-toxic 00108087

00104335

Core

>5423 Practically Non-toxic 00134006 Core

>5620 Practically Non-toxic 00132908 Core

Alachlor >5000 Practically Non-toxic 00093660 Core

>5620 Practically Non-toxic 00106553 Core

>5620 Practically Non-toxic 00106554 Core

Acetochlor >4171 Slightly toxic 41565130 Core

>4610 Slightly toxic 41565131 Core

>5620 Practically Non-toxic 00064711 Core

>5620 Practically Non-toxic 00064710 Core

Metolachlor >10000 Practically Non-toxic 0016425 Core

>10000 Practically Non-toxic 0016426 Core

*Technical Grade Material
169

Table 67: Comparison of Freshwater Fish 96-hr LC50 data (ppm) for Propachlor, Acetochlor,

Alachlor and Metolachlor.

Chemical 96-hr LC50* Category MRID No. Classification

Propachlor 0.23 Highly toxic 40098001 Core

0.17 Highly toxic 00041335 Core

Alachlor 1.0 Highly toxic 00234628 Core

5.6 Moderately toxic 00234628 Core

2.8 Moderately toxic 00023615 Core

4.3 Moderately toxic 40094602 Core

2.4 Moderately toxic 40094602 Core

Acetochlor 1.2 Moderately toxic 41963306 Core

1.5 Moderately toxic 41565133 Core

0.38 Highly toxic 41565132 Core

1.6 Moderately toxic 41565133 Core

Metolachlor 3.9 Moderately toxic 0018722 Core

4.9 Moderately toxic 0015534 Core

8.0 Moderately toxic 40098001 Core

10.0 Moderately toxic 00018723 Core
170

Table 68: Comparison of Aquatic Invertebrate 48-hour LC50 data (ppm) for Propachlor,

Acetochlor, Alachlor and Metolachlor.

Chemical 48-hr LC50* Category MRID No. Classification

Propachlor 0.79 Highly toxic 40098001 Core

7.8 Moderately toxic 00041336 Core

6.9 Moderately toxic 40098001 Core

Alachlor 21.0 Slightly toxic 40098001 Core

3.2 Moderately toxic 40098001 Core

Acetochlor 8.2 Moderately toxic 41565134 Core

14.0 Slightly toxic 00064714 Core

Metolachlor 25.1 Slightly toxic 226955 Core

23.5 Slightly toxic 40098001 Core

3.8 Moderately toxic 40098001 Core

* Technical grade material

Table 69: Comparison of Estuarine Fish 48-hour LC50 data (ppm) for Propachlor, Acetochlor,

Alachlor and Metolachlor

Chemical 48-hr LC50* Category MRID No. Classification

Propachlor No Data

Alachlor 3.9 Moderately toxic 44524301 Core

Acetochlor 2.1 Moderately toxic 42713102 Core

3.9 Moderately toxic 41565137 Core

Metolachlor 9.8 Moderately toxic 43487101 Core
171

Table 70: Comparison of Estuarine Invertebrate 96-hour LC50/EC50 data (ppm) for Propachlor,

Acetochlor, Alachlor and Metolachlor.

Chemical 48-hr LC50* Category ID # Classification

Propachlor No Data

Alachlor 2.4

1.6

Moderately toxic

Moderately toxic

44524302

44524303

Core

Core

Acetochlor 2.2 Moderately toxic 42713101 Core

8.0 Moderately toxic 41565136 Core

5.3 Moderately toxic 41565135 Core

3.82 Moderately toxic 42713103 Core

Metolachlor 4.9 Moderately toxic 43487103 Core

1.6 Moderately toxic 43487102 Core

Table 71: Comparison of Mammalian Acute Oral LD50 data (mg/kg) for Propachlor,

Acetochlor, Alachlor and Metolachlor

Chemical 96-hr LD50* Category ID # Classification

Propachlor 1800 NA

Alachlor Not Required

Acetochlor 2.2 Moderately toxic 42713101 Core

8.0 Moderately toxic 41565136 Core

5.3 Moderately toxic 41565135 Core

3.82 Moderately toxic 42713103 Core

Metolachlor 4.9 Moderately toxic 43487103 Core

1.6 Moderately toxic 43487102 Core

* Technical grade material
172

11. Environmental Risk Assessment

a. Introduction

Risk Quotients (RQs) are used to evaluate the potential risk to nontarget organisms from the

use of alachlor products. RQs are calculated by dividing an appropriate exposure estimate, (such as

the estimated environmental concentration; EEC) by an appropriate toxicity test effect level. Typical

acute effect levels are: EC25 for terrestrial plants, EC50 for aquatic plants and invertebrates, LC50 for

fish and birds, and LD50 for birds and mammals. Typical chronic effect levels are: No Observed Effect

Level (NOEL) for avian and mammal reproduction studies, and either the NOEL, or the Maximum

Allowable Toxicant Concentration (MATC), (which is the geometric mean of the NOEL and the Low

Observed Effect Level (LOEL), for chronic aquatic studies. The NOEL and LOEL are sometimes

referred to as No Observed Effect Concentration (NOEC) or the Lowest Observed Effect

Concentration (LOEC).

RQs are then compared to established levels of concern (LOC) for determination of potential

ecorisk and the consideration of regulatory action. There are two general categories of LOCs: acute

and chronic. The levels of concern are criteria used to indicate potential risk to nontarget organisms.

The criteria indicate that a chemical, when used as directed, has the potential to cause undesirable

effects on nontarget organisms.

When the risk quotient exceeds the LOC for a particular category of organism, there is

presumed to be risk to that particular category. Risk presumptions for particular categories of

organisms are presented in Table 72 along with the corresponding LOC’s.

Table 72: Levels of Concern and Associated Risk Presumptions: 

Criterion Presumption when Criterion Met

Mammals and Birds

Acute RQ$0.5 High acute risk.

Acute RQ$0.2 Risk that may be mitigated through restricted use.

Acute RQ$0.1 Endangered species may be affected acutely.

Chronic RQ$1 Chronic risk, endangered species may be affected

chronically.

Fish and Aquatic Invertebrates 

Acute RQ$0.5 High acute risk

Acute RQ$0.1 Risk that may be mitigated through restricted use.

Acute RQ$0.05 Endangered species may be affected acutely.

Chronic RQ$1 Chronic risk, endangered species may be affected

chronically.

Plants
Table 72: Levels of Concern and Associated Risk Presumptions: 

Criterion Presumption when Criterion Met

173

RQ$1 High risk.

RQ$1 Endangered plants may be affected.

b. Risk to Nontarget Terrestrial Animals

Although available information does not indicate acute risk concerns for birds or mammals,

an LC50 measurement for a small mammal would be required for a conclusive finding.

Birds

Alachlor emulsifiable concentrate at a maximum rate of 6 lbs a.i./A, would produce a

maximum expected concentration of approximately 1440 ppm on range grasses. (Note that the

maximum single application rate is now 4 lb a.i./A.) Alachlor is practically nontoxic to birds on a

dietary basis: in the acute tests with two avian species, little or no mortality was observed at the

highest measured concentration (5620 ppm). Therefore, no exceedances of Agency levels of concern

for acute dietary risk are expected. 

The avian acute oral data (LD50 = 1499 mg/kg) can be used to evaluate avian exposure to

granules. The potential hazard to birds from exposure to granules should be slight. Granules are

deposited typically in bands 6 inches wide, with 32 inches between band centers. This implies that

the pesticide is applied to an area of 8,163 square feet in every acre. At the maximum label rate (for

granular uses) of 4.0 lb ai per acre, there will be 222 mg ai/sq.ft. for the area within bands. If 85%

of the granules are incorporated (Erbach and Tollefson, 1983) the potential surface residue is

33 mg/sq.ft. This value does not indicate an acute toxicity concern for non-endangered species

(LOC=0.5). Exposures exceeding 150 mg/sq ft would exceed the endangered species LOC of a tenth

of the LD50. Without incorporation, exposure could approach this level of concern. However, the

registrant has indicated that Lasso ®II is applied in 10 and 14-inch bands, reducing the level of

exposure and attenuating the concern.

Assessment of chronic effects to terrestrial vertebrates is based on results of reproduction

studies. Properties and use conditions of alachlor indicate a need for such studies. To date the

Agency has not received or reviewed data on possible reproductive or growth effects to birds from

exposure to alachlor. There is some certainty that the nesting and breeding seasons of many bird

species will coincide with the usual preemergent application periods for alachlor. The persistence of

the compound indicates that it will be available for a relatively long period of time on the application

site, with an aerobic soil half life of 2-3 weeks and longer half lives for abiotic processes (photolysis,

hydrolysis).
174

Mammals

Available information for mammals is inconclusive regarding concerns for acute risk. LD50

values for laboratory rats indicate slight acute toxicity. An LC50 measurement would be required to

calculate a risk quotient for non-target mammals. It is common for mammals to be somewhat less

sensitive than birds, and risk quotients calculated above for birds do not indicate a concern for acute

effects.

Regarding the possibility of chronic effects on mammals, three-generation rat studies

produced a parental/offspring systemic toxicity NOEL of 10 mg/kg/day and an LOEC of 30

mg/kg/day. (MRID No. 00075062) Renal toxicity was observed in F2 males. There were no effects

on reproductive parameters. The rat developmental toxicity study showed maternal and

developmental effects at dose levels of 400 mg/kg/day and a NOEC of 150 mg/kg/day. (MRID No.

00043645) Based on the computations for mg ai/sq ft for a granular application, the LOEC for a 1

kg mammal could be contained within a square foot of surface area. Higher exposure is expected for

surface application with no incorporation. Ingestion of this amount of active ingredient for the

extended periods represented in these studies would, however, seem unlikely as the herbicide would

dissipate downward or laterally once irrigation or rainfall events occurred. In the absence of rainfall,

irrigation is recommended within five days of planting to move the chemical to the root zone. 

c. Risk to Nontarget Aquatic Animals

Freshwater Animals

The following features of alachlor use are relevant to the determination of aquatic exposures:

(1) alachlor is a pre-emergent herbicide and is usually applied only once a year, (2) there are some

postemergence uses that allow two applications, and (3) in the absence of rainfall, irrigation is

recommended within five days of planting to move the chemical to the root zone.

Sufficient information is available to characterize the toxicity of alachlor to freshwater

animals. Alachlor shows moderate acute toxicity to both coldwater fish and warmwater fish, based

on measurement with TGAI or formulated EC 45. Alachlor TGAI and formulated products (42-

45%EC) are slightly to moderately toxic to freshwater aquatic invertebrates on an acute basis.

Alachlor is highly toxic to freshwater fish and invertebrates chronically. The LOEC values

for growth and reproductive effects are below 400 ppb. NOEC's are below 190 ppb.

Alachlor is not expected to cause freshwater fish or invertebrates to be at acute risk. Results

of screening level modeling do not exclude the possibility of chronic effect threshold exceedance for

fish and invertebrates through spray drift or runoff in areas close to application sites, particularly for

smaller bodies of water with little inflow or outflow. Based on monitoring results, chronic thresholds

in areas farther down the watershed from these smaller tributaries or ponds are not expected to

exceed acute or chronic levels of concern for fish or invertebrates. 
175

Estuarine and Marine Animals

Sufficient data are available to characterize alachlor as being only moderately toxic to

saltwater fish (sheepshead minnow), saltwater mysid and shellfish (Eastern oyster). 

Bioaccumulation

Alachlor is not expected to bioaccumulate significantly in fish, based on high solubility (240

ppm), and relatively low octanol/water partition coefficient (434). 

d. Risk to Nontarget Plants

Toxicity data for plants, though incomplete, are sufficient to characterize alachlor as highly

toxic for both terrestrial and aquatic plants. Alachlor poses substantial risks to aquatic and terrestrial

plants near use sites. Terrestrial plants may be exposed to alachlor via drift and runoff from areas of

application, or via irrigation with contaminated ground water. Aquatic plants may be exposed via

runoff or drift, or by discharge of contaminated ground water into surface water. 

Aquatic Plants 

Alachlor has an aquatic plant EC50 of 1.64 Fg/L and NOEC of 0.35 μg/L, based on a green

alga study. The risk quotients (based on screening models) using this EC50 range from 21 to 124,

values that substantially exceed the level of concern (LOC=1). Based on monitoring results average

detection levels often exceed levels of concern for aquatic plants.

Measurements of alachlor in surface and ground water were previously described in this

document. The EC50 of 1.64 μg/L for aquatic plants approximately equals the alachlor MCL (2

μg/L); therefore the frequency of acute exposures exceeding the LOC for plants (LOC=1)

approximately equals the frequency of exceeding the MCL. 

Aquatic plants may be adversely affected by alachlor in ground water, in places where ground

water discharges into surface water. Regarding ground water, the measured concentration of alachlor

was higher than the MCL in 21% of wells (99 of 467 wells) that had detectable alachlor, as recorded

in the Pesticides in Ground Water Database.

Terrestrial Plants

For terrestrial plants, the RQ is the ratio of the EEC to the EC25, and RQ values 1 or larger

indicate high risk. Based on calculations that follow, RQ values are equal to 5 or larger, which is

indicative of high risk. 

Typically alachlor is applied by ground equipment at rates of 4 lbs a.i./A. With 5% runoff the

EEC is 0.2 lbs a.i./A. The EC25 for seedling emergence was 0.04 lbs a.i./A, based on a study that was
176

found to be supplemental. The corresponding RQ is 5 (0.2/0.04). Alachlor is persistent, so additional

applications would be additive, to some extent. 

Semi-Aquatic Plants

Semi-aquatic plant species live for some part of a year in wet soil near freshwater wetlands

or estuarine marshes. For these plants, the most appropriate toxicity measurements are those for

terrestrial plants. Exposure scenarios are similar to those described previously for aquatic organisms.

Risk to semi-aquatic plants exceeds levels of concern. Risk is assessed using two different

risk quotients, representing exposure by drift and runoff. Both are compared to an LOC of 1. 

• A risk quotient based on exposure to aerial drift of alachlor is as follows: Alachlor

is applied aerially at 4 lbs a.i./A, and drifts to a plot with area equal to that of the

application plot. A loading of 0.2 lbs a.i./A (=5% drift) is calculated as for aquatic

organisms. The most applicable toxicity data is that for vegetative vigor of terrestrial

plants, with EC25 measurements as low as 0.044 lbs a.i./A. The value of the risk

quotient is 0.2 / 0.044 = 5.

• A risk quotient based on exposure to runoff of water contaminated with alachlor is

calculated as follows: If the pesticide is applied aerially at 4 lbs a.i./A to a 10-acre

application plot and is transported to a 1-acre plot, a loading of 1.2 lbs a.i./A is

calculated. The most applicable toxicity data is that for germination and growth of

terrestrial plants, with EC25 measurements as low as 0.0067 lbs a.i./A. The value of

the risk quotient is 1.2 / 0.0067 = 179.

e. Aquatic LOC Exceedances

For freshwater animals (fish or invertebrates) exposure estimates based on Tier I modeling

(GENEEC) exceed LOCs (levels of concern) only for chronic effects, and only at application rates

of 4 lb ai/A (invertebrates) without incorporation. For estuarine/marine organisms (fish, shrimp and

shellfish), exposure estimates based on Tier 1 modeling (GENEEC) do not exceed concern levels for

acute effects. (See Table 73)

Table 73: Alachlor Screening Level Aquatic EECs Generated by GENEEC, with LOC

Exceedances.

Application

Rate/Method/Incorporation

EEC Estimates Over Time (ppb) Species with LOC exceedance,

(risk quotient)

Peak 4 Days 21 Days 56 Days

1.0lb Granular/Ground/none 33 32.7 30.7 27.4 Aquatic Plant (21) 

2.0lb Granular/Ground/none 66.3 65.5 61.5 58.9 Aquatic plant (41)
Table 73: Alachlor Screening Level Aquatic EECs Generated by GENEEC, with LOC

Exceedances.

Application

Rate/Method/Incorporation

EEC Estimates Over Time (ppb) Species with LOC exceedance,

(risk quotient)

Peak 4 Days 21 Days 56 Days

177

4.0lb Granular/Ground/none 133 131 123 110 Daphnid Chronic NOEC (1)

Aquatic Plant (83)

1.25lb ai/groundspray/none 39 38 36 32 Aquatic Plant (24)

2.5lb ai/groundspray/none 78 77 72 65 Aquatic Plant (49)

3.0 lb ai/groundspray/none 94 93 87 78 Daphnid Chronic (1) 

Aquatic Plant (57)

4.0lb ai/groundspray/none 125 124 116 104 Daphnid Chronic NOEC (1)

Aquatic plant EC50 (76)

4.0 lb ai/groundspray/2.0

inch incorporation

64 63 59 53 Aquatic plant (40)

2.0 lb ai/A twice

groundspray/no incorp./30

day interval

92 91 85 76 Daphnid Chronic NOEC (1)

Aquatic Plant (57)

Alachlor concentration levels observed in monitoring studies do not indicate a risk for acute

or chronic effects on aquatic animals. Thus, while a chronic risk cannot be dismissed for small,

shallow, relatively static bodies of water (such as farm ponds or small freshwater marshes) from

unincorporated applications of alachlor at 4 lbs ai/A (invertebrates), the information available suggests

that impacts are not expected in larger water bodies such as rivers or large lakes. (See Tables 74, 75,

and 76)

Table 74: USGS Mississippi River Basin Survey, 1991-19921

Location Sampled 

(24 Samples per location)

Alachlor Concentration (μg/L)

LOC Exceedance-Organisms

Affected Peak Arithmeti

c average

Annual

TWMC

White River, Hazelton, In. 3.2 0.3 0.22 Aquatic Plants-(Peak only;

based on EC50 (=1.64 ug/L)

Ohio River, Grain Chain, Il. 0.40 0.08 0.07 No
Table 74: USGS Mississippi River Basin Survey, 1991-19921

Location Sampled 

(24 Samples per location)

Alachlor Concentration (μg/L)

LOC Exceedance-Organisms

Affected Peak Arithmeti

c average

Annual

TWMC

178

Miss. River, near Clinton, IA. 0.85 0.16 0.10 No

Illinois River, Valley City, Il 3.00 0.40 0.22 Aquatic Plants-(Peak only,

based on EC50)

Platte River, Louisville, NE 3.60 0.43 0.22 Aquatic Plants-(Peak only,

based on EC50)

Missouri River, Hermann,

Mo.

0.92 0.19 0.12 No

Miss. River, near Thebes, Il. 0.86 0.27 0.23 No

Miss. River, Baton Rouge,

LA.

0.46 0.12 0.09 No

1Based on bi-weekly samples May to August and weekly samples Sept. to Dec. 1 (Coupe et. al. 1995).

Table 75: Illinois Surface Water Survey, 1986-19881

Site Type

Alachlor Concentration as a Range

(over sites and years) (ug/L) LOC Exceedance

Organism Effected

Range of Peak

values

Range of

annual TWMC

Illinois Rivers (21 Sites-18 Rivers) 0.02- 8.5 0.02-0.65 Aquatic Plants based on

EC50

Illinois Creeks (9 Creeks) 0.02-18.0 0.02-2.0

1

 Based on samples from 30 sites representing different streams and rivers, 4-7 samples per yr at each site

(Moyer and Cross, 1990).

Table 76: Summary of Chesapeake Bay Fall Line Toxics Monitoring Program for Alachlor

Detections in Major Streams.

Location Range detected

μg/L

Mean

μg/L

LOC Exceedances

by Mean

Susquehanna River <2.05-23.1 4.4 Aquatic Plants, 

based on EC50
Table 76: Summary of Chesapeake Bay Fall Line Toxics Monitoring Program for Alachlor

Detections in Major Streams.

179

Potomac River 2.5-20.9 4.1

James River 7.5-20.2 2.9

f. Environmental Risk Summary

An evaluation of the risk to nontarget organisms from the use of alachlor products, combining

toxicity data with potential exposure, indicates that:

C Alachlor poses a potential risk to terrestrial animals on a chronic basis. Additional

information must be submitted by the registrant to rule out risk.

C The granular formulations and high use rate pose the greatest risk to nontarget organisms.

C Alachlor levels observed in surface water monitoring studies could result in extensive adverse

effects on aquatic plants.

C Aquatic animals are not at acute risk as a result of exposure to alachlor, but chronic effects

may be observed under certain circumstances.

IV. RISK MANAGEMENT AND REREGISTRATION DECISION

a. Determination of Eligibility

Section 4(g)(2)(A) of FIFRA calls for the Agency to determine, after submission of relevant

data concerning an active ingredient, whether products containing the active ingredients are eligible

for reregistration. The Agency has previously identified and required the submission of the generic

(i.e. active ingredient specific) data required to support reregistration of products containing alachlor

as an active ingredient. The Agency has completed its review of these generic data, and has

determined that the data are sufficient to support reregistration of all products containing alachlor.

Appendix B identifies the generic data requirements that the Agency reviewed as part of its

determination of reregistration eligibility of alachlor, and lists the submitted studies that the Agency

found acceptable.

The data identified in Appendix B were sufficient to allow the Agency to assess the registered

uses of alachlor and to determine that alachlor can be used without resulting in unreasonable adverse

effects to humans and the environment. The Agency therefore finds that all products containing

alachlor as an active ingredient are eligible for reregistration. The reregistration of particular products

is addressed in Section V of this document. 

The Agency made its reregistration eligibility determination based upon the target database

required for reregistration, the current guidelines for conducting acceptable studies to generate such

data, published scientific literature, etc. and the data identified in Appendix B. Although the Agency

has found that all uses of alachlor are eligible for reregistration, it should be understood that the
180

Agency may take appropriate regulatory action, and/or require the submission of additional data to

support the registration of products containing alachlor, if new information comes to the Agency's

attention or if the data requirements for registration (or the guidelines for generating such data)

change.

b. Determination of Eligibility Decision

1. Eligibility Decision

Based on the reviews of the generic data for the active ingredient alachlor, the Agency has

sufficient information on the health effects of alachlor and on its potential for causing adverse effects

in fish and wildlife and the environment. The Agency has determined that alachlor products, labeled

and used as specified in this Reregistration Eligibility Decision Document (RED), will not pose

unreasonable risks or adverse effects to humans or the environment. If the terms and conditions of

registration for products containing the active ingredient alachlor are amended as specified in this

RED, then the Agency concludes that products containing alachlor are eligible for reregistration.

2. Eligible and Ineligible Uses 

The Agency has determined that all uses of alachlor are eligible for reregistration.

c. Regulatory Position

To lessen the risks posed by alachlor, EPA is requiring the following mitigation measures for

alachlor-containing products.

To protect non-target species:

- Require labeling as specified in Section V.

To control surface water contamination:

- Require labeling as specified in Section V.

- Require labeling to implement spray drift best management practices

To control ground water contamination:

- Require labeling as specified in Section V.

- Classify alachlor as a Restricted Use Pesticide (RUP) for ground water concerns

- Add labeling language requiring a 50 ft setback of mixing and loading activities from wells,

rivers, or lakes unless such activity is protected by an impervious pad.

- After promulgation of the Ground Water and Pesticides Management Plan Rule, require use

in accordance with an approved State or Tribal Management Plan 
181

To protect workers:

- For liquid (emulsifiable concentrate) formulations for workers supporting groundboom

application require that mixers, loaders, and persons cleaning equipment must wear longsleeved shirt, long pants, chemical-resistant gloves, chemical-resistant footwear, and

chemical-resistant apron.

- For dry flowable formulations for workers supporting groundboom application require that

mixers, loaders, and persons cleaning equipment must wear long-sleeved shirt, long pants,

chemical-resistant gloves, chemical-resistant footwear, and chemical-resistant apron.

- For liquid (emulsifiable concentrate) formulations for workers supporting aerial application

require that mixers and loaders must wear long-sleeved shirt, long pants, and chemical

resistant gloves, and the use of a closed transfer system. 

- For dry flowable formulations for workers supporting aerial application require that mixers

and loaders must wear long-sleeved shirt, long pants, and chemical resistant gloves, and the

use of a closed transfer system. 

-For mixers and loaders who impregnate dry bulk fertilizer require long-sleeved shirt, long

pants, and chemical-resistant gloves, and the use of a closed transfer system. 

To control the amount of alachlor present in rotated crops:

- Until the rotational crop data are received and reviewed, rotation to crops not specified on

this label is prohibited.

1. Food Quality Protection Act Findings

The following is a summary of the Agency’s regulatory position and rationale for managing

the risks associated with uses of alachlor.

a. Determination of Safety for U.S. Population

EPA has determined that the established tolerances for alachlor, with amendments and

changes as specified in this document, meet the safety standards under the FQPA amendments to

section 408(b)(2)(D) of the FFDCA, and that there is a reasonable certainty of no harm for the

general population. In reaching this determination, EPA has considered the available information on

the aggregate exposures (both chronic and carcinogenic) from food and drinking water. 

The Agency has concluded that there are no alachlor products registered for home use, or use

in or around schools, parks or other public areas. For this reason a residential assessment was not

conducted and there is no residential assessment to aggregate with the total dietary assessment .

As previously discussed, available data do not indicate any evidence of significant toxicity

from a one day or single event exposure by the oral route; therefore, an acute dietary assessment was

not conducted.
182

The Agency assessed the chronic (non-cancer) dietary risk using the chronic RfD of 0.01

mg/kg/day based a NOEL of 1 mg/kg/day from a one year chronic dog study (with an uncertainty

factor of 100 to account for interspecies extrapolation and intraspecies variability). The Agency's

aggregate chronic risk assessment was performed considering exposures from food and water.

Values ranged from less than 1% to 4% of the RfD. The Agency concluded that the chronic dietary

risk from food containing residues of alachlor and from consumption of water containing residues of

alachlor and alachlor ESA is not of concern. 

Using the MOE approach, the Agency calculated carcinogenic dietary risk using two

endpoints of concern: the NOEL of 14 mg/kg/day for stomach tumors and 0.5 mg/kg/day for nasal

tumors. The Agency's estimated MOEs for aggregate dietary carcinogenic risk considering exposures

from food and water. The MOEs ranged from 29,000 to 1,400,000 indicating that the dietary cancer

risk from the recommended uses of alachlor is not expected to be of concern. 

Using the Q1

*

 approach, the Agency calculated carcinogenic dietary risk using the Q1

*

 of 0.08

(mg/kg/day)-1. The Agency's estimated risks for aggregate dietary carcinogenic risk considering

exposures from food and water. The risks ranged from 7.8 x 10-7 to 1.4 x 10-6 which is generally

within the risk range considered to be negligible.

With regard to water monitoring data, sufficient analytical information on detections of all

alachlor degradates were not available. The available information indicates that alachlor ESA is

detected more often and in larger concentrations than alachlor, and that degradates of alachlor are

probably more mobile and more persistent than alachlor per se. Toxicity information is available only

for alachlor ESA. Due to the lack of available information on detections in ground and surface water

of all degradates of alachlor (of which alachlor ESA is only one degradate) and on the toxicity of

these degradates, the Agency is concerned about the exposure to drinking water containing alachlor

and all alachlor degradates.

Alachlor, acetochlor, metolachlor, butachlor, and propachlor are structurally similar and

therefore may share a common mechanism of toxicity. For the purpose of implementation of FQPA,

common mechanism of toxicity is defined as pertaining to two or more pesticides that produce an

adverse effect(s) to human health by the same, or essentially the same, sequence of major biochemical

events. On August 6, 1998, the Notice of Availability for the “Guidance for Identifying Pesticide

Chemicals that have a Common Mechanism of Toxicity for Use in Assessing the Cumulative Toxic

Effects of Pesticides“ was published in the Federal Register. (Federal Register, Volume 63, No. 151).

The Agency is proposing to use the following process for identifying those pesticides that share a

common mechanism of toxicity: (1) identify pesticides that are likely to have a common mechanism

of toxicity using available information on structural similarity, mechanism of pesticidal action, and

common toxic effect, (2) identify the mechanism of toxicity of each pesticide, and (3) categorize

pesticides according to mechanism of toxicity. 

At this time the Agency has not yet made a final decision concerning a possible common

mechanism of toxicity for alachlor, acetochlor, metolachlor, butachlor, and propachlor to
183

scientifically apply that information to the tolerance decision. Therefore, for the purposes of this

decision document, the tolerance decision will be reached based upon the best available and useful

information for alachlor only. Thus, the alachlor risk assessment has been performed assuming that

no common mechanism of toxicity exists. 

However, the process for determining whether a common mechanism of toxicity exists has

begun, but is not yet completed. Thus, the decisions made in this RED will be reexamined after the

Agency (1) finalizes the process for determining whether a common mechanism of toxicity exists for

these chemicals, (2) determines those chemicals with which alachlor does share a common mechanism

of toxicity (cluster), (3) determines the potency equivalencies for each chemical of the cluster, (4)

adds the potency equivalencies to determine the cumulative magnitude of the effect, and (5) after

reviewing the use information/patterns, determines for which of the exposures/scenarios for which

of the chemicals that cumulative exposure exists. Once the methodologies and procedures for

integrating information concerning common mechanism of toxicity into risk assessments are

developed, the Agency can determine the appropriateness of a cumulative assessment.

b. Determination of Safety for Infants and Children

EPA has determined that the established tolerances for alachlor, with amendments and

changes as specified in this document, meet the safety standards under the FQPA amendments to

section 408(b)(2)(C) of the FFDCA, and that there is a reasonable certainty of no harm for infants

and children. The safety determination for infants and children considers the factors noted above for

the general population, but also takes into account the possibility of increased dietary exposure due

to the specific consumption patterns of infants and children, as well as the possibility of increased

susceptibility to the toxic effects of alachlor residues in this population subgroup.

In determining whether or not infants and children are particularly susceptible to toxic effects

from alachlor residues, EPA considered the completeness of the database for developmental and

reproductive effects, as well as other available information such as the nature of the effects observed.

There is no evidence of increased susceptibility of rats or rabbits to in utero and/or postnatal

exposure. There are no data gaps for the assessment of the effects of alachlor following in utero

and/or postnatal exposure.

Based on the current data requirements, alachlor has a complete database for developmental

and reproductive toxicity. Reliable studies cited earlier in this document indicate no special sensitivity

of young organisms to alachlor. Therefore, the Agency has concluded that the 10X FQPA safety

factor for the protection of infants and children can be removed.

EPA estimates that the residues of alachlor in the diets of children (1 - 6 years) represent less

than 1% of the chronic RfD and residues in drinking water, including residues of alachlor ESA,

represent approximately 3% of the chronic RfD. The aggregate chronic dietary exposure for infants

and children utilizes approximately 4% of the chronic RfD. Thus, the Agency concludes that

aggregate risks for infants and children resulting from alachlor uses are not of concern.
184

In deciding to continue to make reregistration determinations during the early stages of FQPA

implementations, EPA recognizes that it will be necessary to make decisions relating to FQPA before

the implementation process is complete. In making these early, case-by-case decisions, EPA does

not intend to set broad precedents for the application of FQPA to its regulatory determinations.

Rather, these early decisions will be made on a case-by-case basis and will not bind EPA as it

proceeds with further policy development and rulemaking that may be required. 

If EPA determines, as a result of this later implementation process, that any of the

determinations described in this RED are no longer appropriate, the Agency will consider itself free

to pursue whatever action may be appropriate, including but not limited to, reconsideration of any

portion of this RED.

c. Endocrine Disrupter Effects

EPA is required to develop a screening program to determine whether certain substances

(including all pesticides and inerts) "may have an effect in humans that is similar to an effect produced

by a naturally occurring estrogen, or such other endocrine effect..." The Agency is currently working

with interested stakeholders, including other government agencies, public interest groups, industry

and research scientists in developing a screening and testing program and a priority setting scheme

to implement this program. Congress has allowed 3 years from the passage of FQPA (August 3,

1999) to implement this program. At that time, EPA may require further testing of this active

ingredient and end use products for endocrine disrupter effects.

2. Tolerance Reassessment

The tolerances listed in 40 CFR §180.249 are for the combined residues of alachlor and its

metabolites (calculated as alachlor).

The Agency has determined that all alachlor metabolites which can be converted to 2,6-

diethylaniline (DEA) and 2-ethyl-6-(1-hydroxyethyl)aniline (1-HEEA) upon basic hydrolysis are to

be regulated and will be included in the tolerance expression. Therefore, the tolerance expression in

40 CFR §180.249 should be modified as follows: "Tolerances are established for the combined

residues of the herbicide alachlor (2-chloro-2',6'-diethyl-N-(methoxymethyl) acetanilide) and its

metabolites which can be converted to 2,6-diethylaniline or 2-ethyl-6-(1-hydroxyethyl)aniline upon

basic hydrolysis, (calculated as alachlor), in or on the following raw agricultural commodities: ...".

Thus, for some commodities tolerance increases will be necessary. The more recent residue

chemistry data reflect analysis for two classes of alachlor metabolites (DEA and HEEA); whereas

some of the older data used to establish the existing tolerances reflect analysis for DEA metabolites

only.

Sufficient data are available to ascertain the adequacy of the established tolerances listed in

40 CFR §180.249 for beans, dry; beans, lima(green); corn, sweet (K + CWHR); corn, grain; sorghum
185

grain and fodder; eggs; milk; and fat, meat, and meat byproducts of cattle, goats, hogs, horses,

poultry, and sheep. See Table 77 for modifications in commodity definitions.

Tolerances for the following commodities have been reassessed based on the available data:

corn, field, forage, and stover; corn, pop, grain, and stover (translated from field corn grain); sweet

corn, forage and stover; peanuts; and soybeans. 

Field rotational crop studies are still required for a root crop and a leafy vegetable; rotational

crop tolerances are needed. Monsanto plans to support cereal grains (except rice), and non-grass

animal feeds as rotational crops. 

Table 77: Tolerance Reassessment Summary.

Commodity

Current Tolerance

(ppm)

Tolerance

Reassessment

(ppm)

Correct Commodity

Definition/Comment

Beans, dry 0.1 0.1

Beans, forage 0.2 5.0 Cowpeas, forage

Beans, hay 0.2 5.0 Cowpeas, hay

Beans, lima (green) 0.1 0.1 Beans, succulent lima

Cattle, fat 0.02 0.02

Cattle, mbyp 0.02 0.02

Cattle, meat 0.02 0.02

Corn, fodder 0.2 2.0 Corn, field, stover

2.0 Corn, pop, stover

2.0 Corn, sweet, stover

Corn, forage 0.2 2.0 Corn, field, forage

2.0 Corn, sweet, forage

Corn, fresh (inc. sweet

K+CWHR) 0.05 0.05 Corn, sweet (K+CWHR)

Corn, grain 0.2 0.2 Corn, field, grain

0.2 Corn, field, pop

Eggs 0.02 0.02

Goats, fat 0.02 0.02

Goats, mbyp 0.02 0.02

Goats, meat 0.02 0.02

Hogs, fat 0.02 0.02

Hogs, mbyp 0.02 0.02
Table 77: Tolerance Reassessment Summary.

Commodity

Current Tolerance

(ppm)

Tolerance

Reassessment

(ppm)

Correct Commodity

Definition/Comment

186

Hogs, meat 0.02 0.02

Horses, fat 0.02 0.02

Horses, mbyp 0.02 0.02

Horses, meat 0.02 0.02

Milk 0.02 0.02

Peanuts 0.05 0.5

Peanuts, forage 3.0 Revoke Feeding restrictions

exist; not considered a

major livestock feed.

Peanuts, hay 3.0 Revoke Feeding restrictions

exist.

Peanuts, hulls 1.5 Revoke Based on Table II,

peanut hulls are not

considered to be a major

livestock feed. 

Poultry, fat 0.02 0.02

Poultry, mbyp 0.02 0.02

Poultry, meat 0.02 0.02

Sheep, fat 0.02 0.02

Sheep, mbyp 0.02 0.02

Sheep, meat 0.02 0.02

Sorghum, fodder 1.0 1.0 Sorghum, grain, stover

Sorghum, forage 2.0 2.0 Sorghum, grain, forage

Sorghum, grain (milo) 0.1 0.1 Sorghum, grain, grain

Soybeans 0.2 1

Soybeans, forage 0.75 Revoke All alachlor products

with uses on soybeans

have feeding restrictions

or are in the process of

being canceled.
Table 77: Tolerance Reassessment Summary.

Commodity

Current Tolerance

(ppm)

Tolerance

Reassessment

(ppm)

Correct Commodity

Definition/Comment

187

Soybeans, hay 0.2 Revoke All alachlor products

with uses on soybeans

have feeding restrictions

or are in the process of

being canceled.

Codex Harmonization

No maximum residue limits (MRLs) for alachlor have been established by CODEX for any

agricultural commodity. Therefore, no questions of compatibility exist with respect to U.S.

tolerances.

3. Ecological Risk Mitigation

For terrestrial animals there are concerns for acute effects. There is not an avian reproduction

study for alachlor, but avian reproduction studies for other acetanilides (metolachlor, acetochlor)

suggest high toxicity on a chronic basis. Based on this, and on consideration of the scope and

seasonal pattern of use (including application at times when birds will be breeding) there is a concern

that alachlor may adversely affect avian reproduction. The information available on persistence of

alachlor is consistent with a chronic concern since alachlor is moderately persistent in soil. The major

dissipation route in soil is microbially mediated, with half lives of 2-3 weeks under aerobic conditions.

Avian reproduction studies are required.

Large scale use of a herbicide ordinarily poses concern for terrestrial plants at least in the

vicinity of application sites. There are no special concerns for effects of alachlor on terrestrial plants,

relative to other herbicides with extensive use. The evaluation of risk to terrestrial plants indicates

high risk from exposure to alachlor drift and runoff. There is no information on toxicity of alachlor

degradates to terrestrial plants.

Alachlor levels observed in surface water monitoring studies could result in extensive effects

on aquatic plants. Such effects could in turn cause population level effects on aquatic animals

(including fish and amphibians) via habitat modification or decreased food supply. Information is not

available on the effects of degradates on aquatic plants.

For aquatic animals, risk quotients based on screening-level exposure estimates do exceed

levels of concern for chronic effects. However, the monitoring information available does not

suggest widespread effects by direct acute or chronic toxicity. The available information does not
188

suggest high toxicity of alachlor degradates to aquatic animals. For estuarine/marine species, risk

quotients, based on screening-level exposure estimates, do not exceed level of concerns for acute

effects for saltwater fish, saltwater mysid or shellfish.

Based on the aquatic plant data, the Agency is confident that adverse effects on aquatic

ecosystems, including potential for population level effects on aquatic animals, will occur.

Alachlor is expected to have some adverse effects on terrestrial plants, at least close to

application sites. The greatest concern at present is for impacts on aquatic ecosystems, resulting from

effects on aquatic plants, and perhaps occasionally from direct effects on aquatic animals. 

Substantial reduction in the risk to aquatic species and ecosystems can only be obtained by

a widespread reduction in use. The registrant has voluntarily reduced the maximum single application

rate of alachlor from 6 to 4 lb ai/acre. New labels with the 4 lb ai/acre rate were approved by the

Agency on June 30, 1998.

4. Surface Water Protection Measures

Alachlor levels observed in monitoring studies are sufficient to result in effects on aquatic

plants and indirectly on aquatic animals. The available monitoring information indicate that drinking

water supply systems usually comply with the Safe Drinking Water Act. Alachlor in the water

sources (i.e., annual averages) will rarely exceed the current MCL of 2 μg/L. Particularly relevant

sources of monitoring information are recent (1992-1996), extensive data collected by the Acetochlor

Registration Partnership monitoring 175 surface water sites, and by the US Geological Survey in

reconnaissance surveys of Midwestern streams and reservoirs. Such data may reflect reported

substantial decreases in alachlor use. However, the concentration of alachlor ESA in surface water

poses a potential human health risk. The concentration of alachlor ESA often greatly exceeds the

concentration of parent alachlor and often occurs at concentrations of several ppb even in early spring

before alachlor application. 

At this time the toxicity of alachlor ESA to certain aquatic species cannot be fully assessed.

Additional studies to characterize the potential ecological effects of alachlor ESA are required. There

are concerns about the possible risk posed by exposure to other major degradates of alachlor such

as alachlor DM-oxanilic acid, alachlor oxanilic acid, and alachlor sulfinylacetic acid.

Since available monitoring data show that alachlor degradates are more frequently found than

the parent, validated analytical methods for these degradates (including alachlor ESA) are needed.

These methods must have minimum detection limits of equal to or less than 0.1 μg/L in water. In

addition to the parent alachlor, it is required that the registrant supply standards of alachlor

degradates (alachlor ESA, alachlor DM-oxanilic acid, alachlor oxanilic acid, and alachlor

sulfinylacetic acid) to the EPA Pesticide Repository.
189

Labeling as specified in Section V will reduce the potential for incidents of contamination of

surface water. Surface water monitoring, which will include some of the alachlor degradates,

is being performed by the Acetochlor Registration Partnership (ARP), USGS National Water Quality

Assessment Program (NAWQA), and various State Programs.

5. Ground Water Protection Measures

Several recent studies have found alachlor degradates in groundwater samples, including

alachlor ESA and alachlor oxanilic acid. These degradates are more persistent than parent alachlor

and appear to be widespread in groundwater. Alachlor ESA has been detected almost 10 times more

frequently than alachlor, and is the most frequently reported pesticide related compound in ground

water monitoring studies for pesticides in the midcontinent area. Alachlor ESA has been found up

to a maximum concentration of 8.6 μg/L in 45 to 70 percent of Midwestern groundwater wells

sampled in a study focused on near-surface aquifers in corn and soybean growing areas. Another

study (Potter and Carpenter, 1995) sampled groundwater from a cornfield in Massachusetts. The last

application of alachlor was three years prior to the sampling. Twenty alachlor degradation products

as well as atrazine, metolachlor, carbofuran and their various degradation products were detected.

The Agency has significant concerns about the impact alachlor and its degradates may have

on ground water quality. Consideration of environmental chemistry and fate properties indicates that

alachlor and a number of alachlor degradates will leach to ground water. An extensive body of

groundwater monitoring information has been reviewed which confirms that alachlor and alachlor

degradates do in fact contaminate groundwater. 

EPA will take additional measures for the protection of groundwater resources as follows:

C EPA will require labeling as specified in Section V to reduce the potential for incidents of

contamination of groundwater. 

C EPA will classify alachlor as a restricted use pesticide for groundwater concerns.

C EPA has included alachlor in its proposed Ground Water and Pesticides Management Plan

Rule as one of the chemicals that would require an approved State or Tribal Management

Plan to allow its use within the State or Tribe’s jurisdiction.

C EPA will continue to consider results of monitoring by others such as the USGS National

Water Quality Assessment program (NAWQA), and the Acetochlor Registration

Partnership(ARP). 

Additionally, once the Agency’s Ground Water and Pesticides Management Plan Rule is final,

the Agency will utilize as appropriate, sampling information that may be available as a result of State

and Tribal Plans. If new information on the toxicity of the degradates or their cumulative or

aggregate effects come to the Agency’s attention, or if monitoring and sampling data demonstrate

increased risk , then EPA may reassess its position relative to ground water concerns.
190

6. Restricted Use Classification

Currently all alachlor labels contain the following statement “RESTRICTED USE

PESTICIDE due to oncogenicity. For retail sale to and use only by Certified Applicators or persons

under their direct supervision and only for those uses covered by the Certified Applicator’s

certification.”

 This restriction is no longer required. However, the registrant, Monsanto, has voluntarily

offered to classify alachlor as a Restricted Use Pesticide due to groundwater concerns. Thus, alachlor

remains a Restricted Use Pesticide. See Section V Table 78 for labeling language.

7. Pesticides Management Plan (PMP) Candidate

In addition to classifying a pesticide for restricted use for or by a certfied applicator as

discussed above, FIFRA section 3(d)(1)(C)(ii) gives EPA authority to classify a pesticide subject to

such other restrictions, if EPA finds its use may cause unreasonable adverse effects on the

environment. EPA is proposing to restrict the legal sale and use of several pesticides, one of which

is alachlor, by requiring Pesticide Management Plans (PMPs) as an “other restriction” through the

proposed Ground Water and Pesticides Management Plan Rule (formerly, State Management Plan

Rule) (Federal Register, Volume 61, No. 124, June 26, 1996). 

Once the Rule is finalized, the labels of these pesticides would be changed to require use in

accordance with an EPA-approved PMP. All products subject to a PMP would bear the following

statement “For use only in accordance with an EPA-approved Pesticide Management Plan (PMP) for

groundwater protection. Sale and use are prohibited in States and Indian Nations that do not have

an EPA-approved PMP.” Once the Rule becomes effective, use of the chemicals subject to the rule

will not be allowed unless an approved Plan is in place. 

PMPs will provide States and Tribes with the flexibility to protect the groundwater in the

most appropriate way for local conditions. To help States and Tribes achieve the ability to protect

their groundwater, EPA strongly encourages the alachlor registrants to cooperate with States and

Tribes, particularly with monitoring and vulnerability assessments. Registrants are also encouraged

to help with other requirements as outlined in the EPA “Guidance for Pesticides and Ground Water

State Management Plans” EPA 735-B-93-005a, December 1993. Without this cooperation, State

and Tribal lead agencies must assume the major burden for Plan development to address potential

ground water concerns related to the continued use of alachlor. 

 The eligibility determination made at this time is based upon a presumption that registrations

will conform to all applicable requirements of the final regulation addressing this issue.
191

8. Endangered Species Statement

Currently, the Agency is developing "The Endangered Species Protection Program" to identify

all pesticides whose use may cause adverse impacts on endangered and threatened species and to

implement mitigation measures that will eliminate the adverse impacts. The program would require

use restrictions to protect endangered and threatened species at the county level. Consultations with

the Fish and Wildlife Service may be necessary to assess risks to newly listed species or from

proposed new uses. In the future, the Agency plans to publish a description of the Endangered

Species Program in the Federal Register and have available voluntary county-specific bulletins.

Because the Agency is taking this approach for protecting endangered and threatened species, it is

not imposing label modifications at this time through the RED. Rather, any requirements for product

use modifications will occur in the future under the Endangered Species Protection Program.

9. Labeling Rationale

Occupational Labeling Rationale/Risk Mitigation

Alachlor is a restricted use pesticide; therefore, alachlor can be used only by certified

applicators and cannot be purchased or used by the general public. The Agency has not identified any

alachlor products that are intended for home use, or uses in/around schools, parks, or other public

areas. No registered use is likely to involve applications at residential sites.

Restricted Use Classification

Alachlor will be classified as a RUP due to groundwater concerns. 

The Worker Protection Standard (WPS)

The 1992 Worker Protection Standard for Agricultural Pesticides (WPS) established certain

worker-protection requirements (personal protective equipment, restricted-entry intervals, etc.) to

be specified on the label of all products that contain uses within the scope of the WPS. Uses within

the scope of the WPS include all commercial (non-homeowner) and research uses on farms, forests,

nurseries, and greenhouses to produce agricultural plants (including food, feed, and fiber plants, trees,

turf grass, flowers, shrubs, ornamentals, and seedlings). Uses within scope include not only uses on

plants, but also uses on the soil or planting medium the plants are (or will be) grown in. At this time

all registered uses of alachlor are within the scope of the WPS. 

In general, WPS products had to bear WPS-complying labeling when sold or distributed after

April 21, 1994. The WPS labeling requirements pertaining to personal protective equipment (PPE),

restricted-entry intervals (REI), and notification are interim. These requirements are to be reviewed

and revised, as appropriate, during reregistration and other Agency review processes.

Personal Protective Equipment for Handlers (Mixers, Loaders, Applicators, etc.) 
192

For each end-use product, PPE requirements for pesticide handlers are set during

reregistration in one of two ways: 

1. If EPA determines that no regulatory action must be taken as the result of the acute effects

or other adverse effects of an active ingredient, the PPE for pesticide handlers will be based

on the acute toxicity of the end-use product. For occupational-use products, PPE must be

established using the process described in PR Notice 93-7 or more recent EPA guidelines.

2. If EPA determines that regulatory action on an active ingredient must be taken as the result

of very high acute toxicity or certain other adverse effects, such as allergic effects or systemic

effects (cancer, developmental toxicity, reproductive effects, etc.): 

# In the RED for that active ingredient, EPA may establish minimum or "baseline"

handler PPE requirements that pertain to all or most end-use products containing that

active ingredient. 

# These minimum PPE requirements must be compared with the PPE that would be

designated on the basis of the acute toxicity of the end-use product. 

# The more stringent choice for each type of PPE (i.e., bodywear, hand protection,

footwear, eyewear, etc.) must be placed on the label of the end-use product.

Personal protective equipment requirements usually are set by specifying one or more preestablished PPE units -- sets of items that are almost always required together. For example, if

chemical-resistant gloves are required, then long-sleeve shirts, long pants, socks, and shoes are

assumed and are also included in the required minimum attire. If the requirement is for two layers

of body protection (coveralls over a long- or short-sleeve shirt and long or short pants), the minimum

must also include (for all handlers) chemical-resistant footwear and chemical-resistant headgear for

overhead exposures and (for mixers, loaders, and persons cleaning equipment) chemical-resistant

aprons.

Occupational-Use Products

EPA is establishing ai specific requirements for some occupational handlers for certain

formulations of alachlor. The MOE's for short- and intermediate-term exposure were a concern for

some occupational mixers, loaders, applicators, and flaggers. Since the NOELs for estimating shortand intermediate-term occupational risks are different, the resultant MOEs are also different. EPA

is regulating on the intermediate-term endpoint, since (1) the risks resulting from intermediate-term

exposures are greater, and (2) the available information for pre-plant herbicide and fertilizer

applications indicate that a window of approximately 28 days is available once weather and field

conditions are right and equipment can enter the fields. 

For the granular formulations, (for mixer/loader/applicators) the estimated risks were greater

than 100 at baseline attire (i.e., long-sleeve shirt, long pants, shoes, and socks). Therefore, no ai

specific requirements are being established for the granular formulations of alachlor.
193

For the liquid (emulsifiable concentrate) formulations, the risks were greater than 100 at

baseline attire (i.e., long-sleeve shirt, long pants, shoes, and socks) for applicators using groundboom

equipment, and for flaggers. 

However, for mixers and loaders supporting groundboom application, the MOEs estimated

for intermediate term risk are acceptable (i.e., 250 at 4.0 pounds active ingredient per acre and 300

at 3.0 pounds active ingredient per acre) only with the addition of personal protective equipment.

Instead of requiring mixers and loaders to wear a coverall, over their long-sleeve shirts and long

pants, EPA will require the addition of a chemical-resistant apron and chemical-resistant footwear

(plus chemical-resistant gloves). Although EPA has no data to specifically assess the exposure

reduction to mixers and loaders afforded by a chemical-resistant apron, the Agency is persuaded that

the exposure reduction would be significant. Available data indicate that the preponderance of nonhand exposure to mixers and loaders is to the front torso. Therefore, for mixers and loaders the use

of a chemical-resistant apron is probably approximately equivalent to double-layer body protection.

The chemical-resistant footwear will provide an additional, although not quantifiable, reduction in

exposure. 

For mixers and loaders supporting aerial application, the MOEs estimated for intermediateterm risk are 93 at 4.0 pounds active ingredient per acre and 130 at 3.0 pounds active ingredient per

acre) only with the addition of personal protective equipment (i.e., double-layers of body protection

and chemical-resistant gloves). Current labels require the use of a closed (mechanical transfer) system

for all mixer/loaders and/or applicators who treat 300 acres or more annually with pesticides

containing alachlor. Thus, due to the existence of these systems, the Agency does not believe that

requiring closed (mechanical transfer) systems for mixer/loaders supporting aerial application and

chemigation will create an undue hardship. Therefore, for liquid (EC) formulations for workers

supporting aerial applications, EPA will require the use of a closed (mechanical transfer) system.

Workers will be required to wear long pants, long-sleeved shirts, and chemical resistant gloves.

For the dry flowable formulations, the estimated risks from both the short- and intermediateterm endpoint were greater than 100 at baseline attire (i.e., long-sleeve shirt, long pants, shoes, and

socks) for mixers and loaders supporting groundboom application, applicators using groundboom

equipment, and for flaggers. EPA will require the addition of a chemical-resistant apron and

chemical-resistant footwear (plus chemical-resistant gloves).

However, for mixers and loaders supporting aerial application, the MOEs estimated for

intermediate-term risk endpoint are marginal (i.e., 61 at 4.0 pounds active ingredient per acre and 82

at 3.0 pounds active ingredient per acre) even with the addition of personal protective equipment (i.e.,

double-layers of body protection and chemical-resistant gloves). To mitigate the risks Monsanto may

develop water soluble packaging (WSP) for the dry flowable formulations. However, if the WSP

is not practicable, then this use will be voluntarily canceled by Monsanto.

For applicators using fixed- and rotary-wing aircraft to apply the liquid or dry flowable

formulations, the risks are acceptable (i.e., ranging from 500 to 1,600) when enclosed cockpits are
194

assumed. Since the Pesticide Handlers Exposure Database does not contain sufficient data to estimate

exposure to applicators using aircraft with open cockpits, only exposure for aerial applicators using

engineering controls, (i.e., enclosed cockpits) was estimated. Since the MOEs are acceptable at

baseline attire for applicators using groundboom equipment and for flaggers, and the MOEs are high

for applicators using enclosed cockpits, the Agency does not have concerns for handlers who may

apply alachlor using aircraft with open cockpits. Additionally, the Agency does not believe that open

cockpits are being used extensively.

For mixers and loaders who impregnate dry bulk fertilizer with alachlor, the estimated risks

are acceptable (ranging from110-220) for short-term exposures with the use of baseline attire plus

chemical-resistant gloves and a closed transfer system; however the risks are unacceptable (ranging

from 10-20) for intermediate-term exposures even with the use of baseline attire, chemical-resistant

gloves, and a closed transfer system. EPA notes that many assumptions were made in performing this

assessment and acknowledges that many of the assumptions were deliberately intended toward

performing an upper-end assessment. For example, one high-end assumption is that the mixing tower

would run at full capacity for 8 hours a day and thus generate 960 tons of alachlor impregnated

fertilizer. EPA also notes that these estimates are based on using dermal unit exposure data from

PHED V1.1. for a closed mixing/loading system (i.e., mechanical transfer) from individual containers

into mix tanks typically used in agricultural field conditions. The amount of alachlor necessary to

impregnate the tons of fertilizer processed in a day probably involves transfer from huge containers

such as tanker trucks or railroad tank cars, rather than from individual containers. Therefore, using

unit exposure from the available PHED data is likely to result in an over-estimate. EPA currently does

not have data for bulk transfer/loading. Given these and other uncertainties, EPA has determined that

additional data are necessary to appropriately assess this use pattern. Therefore, the Agency is calling

in data on dermal and inhalation exposure to handlers who are engaged in impregnating fertilizer with

alachlor. In the interim, EPA is requiring such handlers to wear long pants, long sleeved shirts, and

chemical-resistant gloves, and to use closed (e.g., mechanical transfer) systems. This exposure

scenario will be reevaluated upon receipt of the requested data.

For handlers who apply dry bulk fertilizer impregnated with alachlor, the estimated risks were

acceptable (ranging from 98 to 1300) at baseline attire using open cabs. Therefore, no ai specific

requirements are being established for the application of dry bulk fertilizer impregnated with alachlor.

 

Post-Application/Entry Restrictions

Occupational-Use Products (WPS Uses)

Restricted-Entry Interval: Under the Worker Protection Standard (WPS), interim

restricted-entry intervals (REI's) for all uses within the scope of the WPS are based on the acute

toxicity of the active ingredient. The toxicity categories of the active ingredient for acute dermal

toxicity, eye irritation potential, and skin irritation potential are used to determine the interim WPS

REI. If one or more of the three acute toxicity effects are in toxicity category I, the interim WPS REI

is established at 48 hours. If none of the acute toxicity effects are in category I, but one or more of
195

the three is classified as category II, the interim WPS REI is established at 24 hours. If none of the

three acute toxicity effects are in category I or II, the interim WPS REI is established at 12 hours. A

48-hour REI is increased to 72 hours when an organophosphate pesticide is applied outdoors in arid

areas. In addition, the WPS specifically retains two types of REI's established by the Agency prior

to the promulgation of the WPS: (1) product-specific REI's established on the basis of adequate data,

and (2) interim REI's that are longer than those that would be established under the WPS.

During the reregistration process, EPA considers all relevant product-specific information to

decide whether there is reason to shorten or lengthen the previously established REI. 

During the reregistration process, EPA determined that the restricted-entry interval for all

occupational-use products that contain alachlor and are within the scope of the Worker Protection

Standard for Agricultural Pesticides (WPS) should be 12 hours. 

Alachlor is not a candidate for the 4-hour REI, since both the acute oral and acute inhalation

toxicity studies are category III.

Early-Entry PPE: The WPS establishes very specific restrictions on entry by workers to

areas that remain under a restricted-entry interval, if the entry involves contact with treated surfaces.

Among those restrictions are a prohibition of routine entry to perform hand labor tasks and a

requirement that personal protective equipment be worn. Under the WPS, these personal protective

equipment requirements for persons who must enter areas that remain under a restricted-entry interval

are based on the acute toxicity category of the active ingredient. 

During the reregistration process, EPA considers all relevant product-specific information to

decide whether there is reason to set personal protective equipment requirements that differ from

those set through the WPS. The RED requirements for early-entry personal protective equipment

are set in one of two ways:

1. If EPA determines that no regulatory action must be taken as the result of the acute effects

or other adverse effects of an active ingredient, it establishes the early-entry PPE requirements

on the basis of the acute dermal toxicity category, skin irritation potential category, and eye

irritation potential category of the active ingredient. 

2. If EPA determines that regulatory action on an active ingredient must be taken as the result

of very high acute toxicity or to certain other adverse effects, such as allergic effects or

delayed effects (cancer, developmental toxicity, reproductive effects), it may establish earlyentry PPE requirements that are more stringent than would be established otherwise.

During the reregistration process, EPA determined that the early-entry personal protective

equipment for all occupational-use products that contain alachlor and are within the scope of the

Worker Protection Standard for Agricultural Pesticides (WPS) are: coverall, chemical-resistant

gloves, and shoes plus socks. 
196

WPS Double Notification Statement:

"Double" notification is the statement on the labels of some pesticide products requiring

employers to notify workers about pesticide-treated areas orally as well as by posting of the treated

areas. The interim WPS "double" notification requirement is imposed if the active ingredient is

classified as toxicity category I for acute dermal toxicity or skin irritation potential. During the

reregistration process, EPA determined that for alachlor double notification is not required.

Other Labeling Requirements

The Agency is also requiring other use and safety information to be placed on the labeling of

all end-use products containing alachlor. For the specific labeling statements, refer to Section V of

this document.

10. Spray Drift Advisory

The Agency has been working with the Spray Drift Task Force, EPA Regional Offices and

State Lead Agencies for pesticide regulation to develop the best spray drift management practices.

The Agency is now requiring interim measures that must be placed on product labels/labeling as

specified in Section V. Once the Agency completes its evaluation of the new data base submitted by

the Spray Drift Task Force, a membership of U.S. pesticide registrants, the Agency may impose

further refinements in spray drift management practices to further reduce off-target drift and risks

associated with this drift. 

V. ACTIONS REQUIRED OF REGISTRANTS

This section specifies the data requirements and responses necessary for the reregistration of

both manufacturing-use and end-use products containing alachlor as an active ingredient..

a. Manufacturing-Use Products

1. Additional Generic Data Requirements

The generic data base supporting the reregistration of alachlor for the above eligible uses has

been reviewed and determined to be substantially complete. The following studies are required and

considered confirmatory to our conclusion of Eligibility for reregistration:

C 71-4 Avian reproduction (two species)

C 122-2 Aquatic plant studies with the parent alachlor with an aquatic macrophyte, a marine

diatom, a blue-green algae and a freshwater diatom (These studies were recently submitted

to the Agency and are now under review.)

C 122-2 Aquatic plant studies with alachlor ESA with 5 aquatic plant species
197

C 171-4 Validated analytical method for degradates, methods must have minimum detection

limits equal to or less than 0.1 ug/L in water

C 231, 232, 233, and 234 (now 875.2400 and 875.2500) Handler exposure studies are required

for impregnating dry bulk fertilizer with alachlor (including use of mini-bulk containers) and

distribution-to-field application exposure scenarios. Samples for dermal and inhalation

exposure should be taken concurrently. Both outdoor and indoor (at least partially enclosed)

sites are required.

2. Labeling Requirements for Manufacturing-Use Products

To remain in compliance with FIFRA, manufacturing use product (MP) labeling must be

revised to comply with all current EPA regulations, PR Notices and applicable policies. The MP

labeling must bear the labeling contained in Table 78 at the end of this section.

b. End-Use Products

1. Additional Product-Specific Data Requirements

Section 4(g)(2)(B) of FIFRA calls for the Agency to obtain any needed product-specific data

regarding the pesticide after a determination of eligibility has been made. The product specific data

requirements are listed in Appendix G, the Product Specific Data Call-In Notice. 

Registrants must review previous data submissions to ensure that they meet current EPA

acceptance criteria (Appendix F; Attachment E) and if not, commit to conduct new studies. If a

registrant believes that previously submitted data meet current testing standards, then study MRID

numbers should be cited according to the instructions in the Requirement Status and Registrants

Response Form provided for each product.

2. Labeling Requirements for End-Use Products

All end-use products should have clear, concise and complete labeling instructions. Proper

labels can improve reader understanding, thereby reducing misuse and the potential for incidents.

Towards this end, the Agency is requiring the following:

Directions for Use:

Directions for Use must be stated in terms that can be easily read and understood by the

average person likely to use or to supervise the use of the pesticide. It must be presented in a format

that is easy to understand and follow. The Directions for Use section of a pesticide label must provide

the necessary information to answer four major categories regarding the use of the pesticide. These

four questions are:

1) Why is the pesticide being used? For what pest(s) or problem?
198

2) Where is the pesticide applied? (Where should it not be applied?)

3) How is the pesticide applied? (What special precautions must the user take? How

much should they use?)

4) When should the pesticide be applied?

In addition, the Agency encourages the use of clearly understood, widely recognized graphic

symbols whenever possible, to clarify the written label.

National Pesticide Telecommunications (NPTN) Hotline Number

All alachlor labels must refer consumers to the NPTN number for additional information. This

reference must bear the labeling contained in Table 78 at the end of this section.

First Aid (Statement of Practical Treatment)

The Agency is requiring that all labels with Statement of Practical Treatment sections be

amended so that these sections are entitled, “First Aid.” First aid statements must be brief, clear,

simple and in straightforward language (conforming to the labeling required by the Agency) so that

the average person can easily and quickly understand the instructions. These statements should be

appropriate for all ages or, when necessary, should include distinctions between the treatments for

different ages.

Labeling Requirements

Table 78 summarizes the labeling requirements being imposed by this RED for all alachlor

products. Any use instructions on current labels that conflict with those listed in Table 78 should be

removed.

For sole-active-ingredient end-use products that contain alachlor: 

• Revise the product labeling to adopt the handler personal protective

equipment/engineering control requirements set forth in Table 78, and .

• Revise the product labeling to adopt the entry restrictions set forth in Table 78. 

For multiple-active-ingredient end-use products that contain alachlor: 

• Compare the handler personal protective equipment/engineering control requirements

set forth in Table 78 to the requirements on the current labeling, then

• Retain the more protective requirements. (For guidance on which requirements are

considered more protective, see PR Notice 93-7).

• Compare the entry restrictions set forth in Table 78 to the entry restrictions on the

current labeling, then

• Retain the more protective restrictions. (A specific time period in hours or days is

considered more protective than "sprays have dried" or "dusts have settled.")
199

The PPE that would be established on the basis of the acute toxicity category of the end-use

product must be compared to the active-ingredient specific personal protective equipment specified

above. The more protective PPE must be placed on the product labeling. For guidance on which PPE

is considered more protective, see PR Notice 93-7.

EPA is not establishing active-ingredient-specific PPE for WPS occupational uses of alachlor

end-use products formulated as a granular, or for the application of dry bulk fertilizer impregnated

with alachlor.
200

Table 78: Summary of Required Labeling Changes for Alachlor Products

Description Required Labeling Placement

Manufacturing Use

One of these statements

may be added to a label to

allow reformulation of the

product for a specific use

or all additional uses

supported by a formulator

or user group

“Only for formulation into a herbicide for the following use(s) [fill blank only with those uses that

are being supported by MP registrant].”

Directions for Use

“This product may be used to formulate products for specific use(s) not listed on the MP label if

the formulator, user group, or grower has complied with U.S. EPA submission requirements

regarding support of such use(s).”

“This product may be used to formulate products for any additional use(s) not listed on the MP

label if the formulator, user group, or grower has complied with U.S. EPA submission

requirements regarding support of such use(s).”

Environmental Hazards

Statements

"This chemical is toxic to terrestrial and aquatic plants, fish and aquatic invertebrates. Do not

discharge effluent containing this product into lakes, streams, ponds estuaries, oceans or other

waters unless in accordance with the requirements of a National Pollutant Discharge Elimination

System (NPDES) permit and the permitting authority has been notified in writing prior to

discharge. Do not discharge effluent containing this product to sewer systems without previously

notifying the local sewage treatment plant authority. For guidance contact your state Water

Board or Regional Office of the EPA.”

End-Use Products Intended for Occupational Use (WPS )

Restricted Use Pesticide

“RESTRICTED USE PESTICIDE due to groundwater concerns. For retail sale to and use only

by Certified Applicators or persons under their direct supervision and only for those uses covered

by the Certified Applicator’s Certification.”

Top of Front Panel and

Beginning of Directions

for Use
Table 78: Summary of Required Labeling Changes for Alachlor Products

Description Required Labeling Placement

201

Notice to Users

While alachlor has produced tumors in laboratory animals, extensive studies have established that

alachlor is unlikely to be a human carcinogen at low levels of exposure. However, even when

used according to label directions, some exposure will result. Therefore, users must read and

follow all Precautionary Statements, Environmental Hazards, and Directions for Use to minimize

exposure to this product.

Beginning of Directions

for Use

Precautionary Labeling

“For information on this pesticide product (including health concerns, medical emergencies, or

pesticide incidents), call the National Pesticide Telecommunications Network at 1-800-858-

7378.”

Precautionary

Statements: Hazards to

Humans and Domestic

Animals

Precautionary Labeling “This product may cause skin sensitization reactions in some people.”

Precautionary

Statements: Hazards to

Humans and Domestic

Animals

PPE Requirements: 

Liquid (emulsifiable

concentrate) and dry

flowable formulations

“Mixers, loaders, and persons cleaning equipment in support of groundboom application must

wear:

-long-sleeved shirt and long pants,

-chemical-resistant gloves,*

-chemical-resistant footwear, and

-chemical-resistant apron.”

*For the glove statement, use the statement established for alachlor through the instructions in

Supplement Three of PR Notice 93-7. 

Precautionary

Statements: Hazards to

Humans and Domestic

Animals

User Safety Requirements

“Follow manufacturer's instructions for cleaning/maintaining PPE. If no such instructions for

washables exist, use detergent and hot water. Keep and wash PPE separately from other

laundry.”

Precautionary

Statements: Hazards to

Humans and Domestic

Animals

(Immediately following

the PPE Requirements)
Table 78: Summary of Required Labeling Changes for Alachlor Products

Description Required Labeling Placement

202

Engineering Controls

“Engineering Controls”

“When handlers use closed systems, enclosed cabs, or aircraft in a manner that meets the

requirements listed in the Worker Protection Standard (WPS) for agricultural pesticides (40CFR

170.240(d)(4.6), the handler PPE requirements may be reduced or modified as specified in the

WPS.”

“Mixers and loaders supporting aerial applications, chemigation, or impregnation of dry bulk

fertilizer are required to use closed systems. The closed system must be used in a manner that

meets the requirements listed in the Worker Protection Standard (WPS for agricultural pesticides

(40CFR 170.240(d)(4)).” 

Precautionary

Statements: Hazards to

Humans and Domestic

Animals (Immediately

following PPE and user

Safety Statements

Engineering Controls for

all Dry Flowable

Formulations

In addition to the above Engineering Controls statement, dry flowable formulations must also

have the following statement:

“Water soluble packaging when used correctly qualify as a closed loading system under the WPS. 

Handlers handling this product while it is enclosed in intact water-soluble packaging are

permitted to wear long-sleeved shirt, long pants, shoes and socks, and chemical resistant gloves.“ 

Precautionary

Statements: Hazards to

Humans and Domestic

Animals 

(Immediately following

User Safety

Requirements)

Engineering Controls for

all Liquid (emusifiable

concentrate) Formulations

In addition to the above Engineering Controls statement, liquid formulations must also have the

following statement:

“Mixers and loaders are required to use closed (mechanical transfer) systems. Handlers using

closed systems are permitted to wear long-sleeved shirt, long pants, shoes and socks, and

chemical resistant gloves.” 

Precautionary

Statements: Hazards to

Humans and Domestic

Animals (Immediately

following User Safety

Requirements)
Table 78: Summary of Required Labeling Changes for Alachlor Products

Description Required Labeling Placement

203

User Safety

Recommendations

“User Safety Recommendations”

“Users should wash hands before eating, drinking, chewing gum, using tobacco, or using the

toilet.“

“Users should remove clothing/PPE immediately if pesticide gets inside. Then wash thoroughly

and put on clean clothing.“

“Users should remove PPE immediately after handling this product. Wash the outside of gloves

before removing. As soon as possible, wash thoroughly and change into clean clothing.”

Precautionary

Statements: Hazards to

Humans and Domestic

Animals

(Must be placed in a

box.)

(Immediately following

Engineering Controls)

Environmental Hazards

for liquid (emulsifiable

concentrate) or dry

flowable formulations

"This chemical is toxic to terrestrial and aquatic plants, fish, and aquatic invertebrates. Do not

apply directly to water or to areas where surface water is present or to intertidal areas below the

mean high-water mark. Runoff may be hazardous to aquatic organisms in neighboring areas.”

Precautionary

Statements under

Environmental Hazards

Section 

Environmental Hazards

for granular product

formulations

“This chemical is toxic to fish, and aquatic invertebrates. Do not apply directly to water or to

areas where surface water is present or to intertidal areas below the mean high-water mark. 

Runoff may be hazardous to aquatic organisms in neighboring areas. Cover or incorporate

granules that are spilled during loading or are visible on soil surface in turn areas. “

Precautionary

Statements under

Environmental Hazards

Section 

Ground and Surface Water

Statements

"Alachlor can contaminate surface water through spray drift. Under some conditions, alachlor

may also have a high potential for runoff into surface water (primarily via dissolution in runoff

water), for several weeks post-application. These include poorly draining or wet soils with

readily visible slopes toward adjacent surface waters, frequently flooded areas, areas over-laying

extremely shallow ground water, areas with in-field canals or ditches that drain to surface water,

areas not separated from adjacent surface waters with vegetated filter strips, and areas over-laying

tile drainage systems that drain to surface water. Do not apply to water or to areas where surface

water is present, or to intertidal areas below the mean high water mark.” 

Environmental Hazards

Section

Ground and Surface Water

Statements “Do not contaminate water when disposing of equipment wash water or rinsate.” Environmental HazardsSection
Table 78: Summary of Required Labeling Changes for Alachlor Products

Description Required Labeling Placement

204

Ground and Surface Water

Statements

"This chemical and/or its metabolites are known to leach through soil into ground water under

certain conditions as a result of registered uses. Use of this chemical in areas where soils are

permeable, particularly where the water table is shallow, may result in ground-water

contamination."

Environmental Hazards

Section

Ground and Surface Water

Statements

“Do not apply to highly permeable soils (as classified by the USDA Natural Resources

Conservation Service) where the depth to ground water is 30 feet or less.”

Environmental Hazards

Section

Restricted-Entry Interval

(required by Supplement

Three of PR Notice 93-7) 

“A 12-hour restricted-entry interval (REI) is required for uses within the scope of the WPS on all

alachlor end-use products. Exception: if the product is soil-injected or soil-incorporated, the

Worker Protection Standard, under certain circumstances, allows workers to enter the treated area

if there will be no contact with anything that has been treated.”

Directions for Use,

Agricultural Use

Requirements Box

Personal protective

equipment required for

early entry

“The PPE required for early entry is:

-coveralls,

-chemical-resistant gloves, and

-shoes plus socks.“

Directions for Use,

Agricultural Use

Requirements Box

Application Restrictions

“Do not apply this product by any method not specified on this label.”

“Do not apply this product in a way that will contact workers or other persons, either directly or

through drift. Only protected handlers may be in the area during application.“

Directions for Use

The following language

must be placed on each

product that can be

applied aerially:

“Aerial Spray Drift Management”

“Avoiding spray drift at the application site is the responsibility of the applicator. The interaction

of many equipment-and-weather-related factors determine the potential for spray drift. The

applicator and the grower are responsible for considering all these factors when making

decisions.”

Directions for Use
Table 78: Summary of Required Labeling Changes for Alachlor Products

Description Required Labeling Placement

205

The following language

must be placed on each

product that can be

applied aerially:

“The following drift management requirements must be followed to avoid off-target drift

movement from aerial applications to agricultural field crops. These requirements do not apply to

forestry applications, public health uses or to applications using dry formulations.

1.The distance of the outer most nozzles on the boom must not exceed 3/4 the length of the

wingspan or rotor.

2.Nozzles must always point backward parallel with the air stream and never be pointed

downwards more than 45 degrees.

Where states have more stringent regulations, they should be observed.

The applicator should be familiar with and take into account the information covered in the

Aerial Drift Reduction Advisory Information.”

Directions for Use 

The following language

must be placed on each

product that can be

applied aerially:

“Aerial Drift Reduction Advisory”

"This section is advisory in nature and does not supersede the mandatory label requirements."

“INFORMATION ON DROPLET SIZE”

“The most effective way to reduce drift potential is to apply large droplets. The best drift

management strategy is to apply the largest droplets that provide sufficient coverage and control. 

Applying larger droplets reduces drift potential, but will not prevent drift if applications are made

improperly, or under unfavorable environmental conditions (see Wind, Temperature and

Humidity, and Temperature Inversions).”

Directions for Use
Table 78: Summary of Required Labeling Changes for Alachlor Products

Description Required Labeling Placement

206

The following language

must be placed on each

product that can be

applied aerially:

“CONTROLLING DROPLET SIZE”

“!Volume - Use high flow rate nozzles to apply the highest practical spray volume. Nozzles with

higher rated flows produce larger droplets.

!Pressure - Do not exceed the nozzle manufacturer's recommended pressures. For many nozzle

types lower pressure produces larger droplets. When higher flow rates are needed, use higher

flow rate nozzles instead of increasing pressure.

!Number of nozzles - Use the minimum number of nozzles that provide uniform coverage.

!Nozzle Orientation - Orienting nozzles so that the spray is released parallel to the airstream

produces larger droplets than other orientations and is the recommended practice. Significant

deflection from horizontal will reduce droplet size and increase drift potential.

!Nozzle Type - Use a nozzle type that is designed for the intended application. With most nozzle

types, narrower spray angles produce larger droplets. Consider using low-drift nozzles. Solid

stream nozzles oriented straight back produce the largest droplets and the lowest drift.”

Directions for Use

The following language

must be placed on each

product that can be

applied aerially:

“BOOM LENGTH”

“For some use patterns, reducing the effective boom length to less than 3/4 of the wingspan or

rotor length may further reduce drift without reducing swath width.”

Directions for Use

The following language

must be placed on each

product that can be

applied aerially:

“APPLICATION HEIGHT”

“Applications should not be made at a height greater than 10 feet above the top of the largest

plants unless a greater height is required for aircraft safety. Making applications at the lowest

height that is safe reduces exposure of droplets to evaporation and wind.”

Directions for Use
Table 78: Summary of Required Labeling Changes for Alachlor Products

Description Required Labeling Placement

207

The following language

must be placed on each

product that can be

applied aerially:

“SWATH ADJUSTMENT”

“When applications are made with a crosswind, the swath will be displaced downward. 

Therefore, on the up and downwind edges of the field, the applicator must compensate for this

displacement by adjusting the path of the aircraft upwind. Swath adjustment distance should

increase, with increasing drift potential (higher wind, smaller drops, etc.)”

Directions for Use

The following language

must be placed on each

product that can be

applied aerially:

“WIND”

“Drift potential is lowest between wind speeds of 2-10 mph. However, many factors, including

droplet size and equipment type determine drift potential at any given speed. Application should

be avoided below 2 mph due to variable wind direction and high inversion potential. NOTE: 

Local terrain can influence wind patterns. Every applicator should be familiar with local wind

patterns and how they affect spray drift.”

Directions for Use

The following language

must be placed on each

product that can be

applied aerially:

“TEMPERATURE AND HUMIDITY”

“When making applications in low relative humidity, set up equipment to produce larger droplets

to compensate for evaporation. Droplet evaporation is most severe when conditions are both hot

and dry.”

Directions for Use
Table 78: Summary of Required Labeling Changes for Alachlor Products

Description Required Labeling Placement

208

The following language

must be placed on each

product that can be

applied aerially:

“TEMPERATURE INVERSIONS”

“Applications should not occur during a temperature inversion because drift potential is high. 

Temperature inversions restrict vertical air mixing, which causes small suspended droplets to

remain in a concentrated cloud. This cloud can move in unpredictable directions due to the light

variable winds common during inversions. Temperature inversions are characterized by

increasing temperatures with altitude and are common on nights with limited cloud cover and

light to no wind. They begin to form as the sun sets and often continue into the morning. Their

presence can be indicated by ground fog; however, if fog is not present, inversions can also be

identified by the movement of smoke from a ground source or an aircraft smoke generator. 

Smoke that layers and moves laterally in a concentrated cloud (under low wind conditions)

indicates an inversion, while smoke that moves upward and rapidly dissipates indicates good

vertical air mixing.”

Directions for Use

The following language

must be placed on each

product that can be

applied aerially:

“SENSITIVE AREAS”

“The pesticide should only be applied when the potential for drift to adjacent sensitive areas (e.g.

residential areas, bodies of water, known habitat for threatened or endangered species, non-target

crops) is minimal (e.g. when wind is blowing away from the sensitive areas).”

Directions for Use

Application Rate Limit for

All End-Use Products

If any alachlor end-use products have application rates that are greater than 4lb ai/acre/year, then

the label must be amended to be no more than 4 lb ai/acre/year.

Directions for Use

Directions for

Application
Table 78: Summary of Required Labeling Changes for Alachlor Products

Description Required Labeling Placement

209

Application Restrictions:

Mixing/Loading Setbacks

“This product may not be mixed or loaded within 50 feet of perennial or intermittent streams and

rivers, natural or impounded lakes and reservoirs. This product may not be mixed/loaded or used

within 50 feet of all wells, including abandoned wells (unless the well has been properly capped

or plugged), drainage wells, and sink holes. Operations that involve mixing, loading, rinsing, or

washing of this product into or from pesticide handling or application equipment or containers

within 50 feet of any well are prohibited unless conducted on an impervious pad constructed to

withstand the weight of the heaviest load that may be positioned on or moved across the pad. 

Such a pad shall be designed and maintained to contain any product spills or equipment leaks,

container or equipment rinse or wash-water, and rain water that my fall on the pad. Surface

water shall not be allowed to either flow over or from the pad, which means the pad must be selfcontained. The pad shall be sloped to facilitate material removal. An unroofed pad shall be of

sufficient capacity to contain at a minimum 110% of the capacity of the largest pesticide

container or application equipment on the pad. A pad that is covered by a roof of sufficient size

to completely exclude precipitation from contact with the pad shall have a minimum containment

capacity of 100% of the capacity of the largest pesticide container or application equipment on the

pad. Containment capacities as described above shall be maintained at all times. The abovespecified minimum containment capacities do not apply to vehicles when delivering pesticide

shipments to the mixing/loading site.”

Directions for Use

Application Restriction

“Do not apply to highly permeable soils (as classified by the USDA Natural Resources

Conservation Service) where the depth to ground water is 30 feet or less.”

Directions for Use

(Under Use Precautions

and Restrictions)

Rotational Crop

Restriction

“Rotation to crops not specified on this label is prohibited” Directions for Use

(Under Use Precautions

and Restrictions)
210

c. Existing Stocks

Registrants may generally distribute and sell products bearing old labels/labeling for 26 months

from the date of the issuance of this Reregistration Eligibility Decision (RED). Persons other than the

registrant may generally distribute or sell such products for 50 months from the date of the issuance

of this RED. However, existing stocks time frames will be established case-by-case, depending on the

number of products involved, the number of label changes, and other factors. Refer to "Existing

Stocks of Pesticide Products; Statement of Policy"; Federal Register, Volume 56, No. 123, June 26,

1991.

The Agency has determined that registrants may distribute and sell alachlor products bearing

old labels/labeling for 26 months from the date of issuance of this RED. Persons other than the

registrant may distribute or sell such products for 50 months from the date of the issuance of this

RED. Registrants and persons other than registrants remain obligated to meet pre-existing Agency

imposed label changes and existing stocks requirements applicable to products they sell or distribute.
211

VI. APPENDICES
212
213

a.Table of Use Patterns Subject to Reregistration

Appendix A - Table of Use Patterns Subject to this RED

Appendix A is 52 pages long and is not being included in this RED. Copies of Appendix A are

available upon request per the instructions in Appendix E.
214

b.Table of the Generic Data Requirements and Studies Used to Make the Reregistration Decision
215

GUIDE TO APPENDIX B

Appendix B contains listings of data requirements which support the reregistration for active

ingredients within the case alachlor covered by this Reregistration Eligibility Decision

Document. It contains generic data requirements that apply to alachlor in all products, including

data requirements for which a "typical formulation" is the test substance.

The data table is organized in the following format:

1. Data Requirement (Column 1). The data requirements are listed in the order in which they

appear in 40 CFR Part 158. the reference numbers accompanying each test refer to the test

protocols set in the Pesticide Assessment Guidelines, which are available from the National

Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161 (703) 605-6000.

2. Use Pattern (Column 2). This column indicates the use patterns for which the data

requirements apply. The following letter designations are used for the given use patterns:

A Terrestrial food

B Terrestrial feed

C Terrestrial non-food

D Aquatic food

E Aquatic non-food outdoor

F Aquatic non-food industrial

G Aquatic non-food residential

H Greenhouse food

I Greenhouse non-food

J Forestry

K Residential

L Indoor food

M Indoor non-food

N Indoor medical

O Indoor residential

3. Bibliographic citation (Column 3). If the Agency has acceptable data in its files, this

column lists the identifying number of each study. This normally is the Master Record

Identification (MRID) number, but may be a "GS" number if no MRID number has been

assigned. Refer to the Bibliography appendix for a complete citation of the study.
216
217

APPENDIX B

Data Supporting Guideline Requirements for the Reregistration of Alachlor

REQUIREMENT USE PATTERN CITATION(S)

PRODUCT CHEMISTRY

830.1550 Product Identity All 00146114 

830.1600

830.1620

830.1650

Starting Material & Mnfg. Process All 00146114, 40396301

830.1670 Formation of Impurities All 00146114, 00152206

830.1700 Preliminary Analysis All 00146114, 00152206

830.1750 Certification of limits All 00146114

830.1800 Analytical Method All 00146114, 00147476, 00152206, 40396301

830.6302 Color All 00146114

830.6303 Physical State All 00146114

830.6304 Odor All 00146114

830.6313 Stability All 00146114

830.7000 pH All 00146114

830.7050 UV 44492301 

830.7200 Melting Point All 00146114

830.7220 Boiling Point N/A

830.7300 Density All 00146114

830.7550 Dissociation Constant N/A
Data Supporting Guideline Requirements for the Reregistration of Alachlor

REQUIREMENT USE PATTERN CITATION(S)

218

830.7550

830.7560

830.7570

Octanol/Water Partition All 00146114, 00152209, 00152210, 40396301

830.7840

830.7860

Solubility All 00146114, 00152209, 40396301

830.7950 Vapor Pressure All 00146114, 00152209

ECOLOGICAL EFFECTS

71-1A Acute Avian Oral - Quail/Duck AB 00079523

71-2A Avian Dietary - Quail AB 43087101

71-2B Avian Dietary - Duck AB 43087001

71-4A Avian Reproduction - Quail AB Data Gap

71-4B Avian Reproduction - Duck AB Data Gap

72-1 Fish Toxicity Bluegill AB 00023615, 00028551, 00028554, 00031525,

40098001, 43774706

72-1 Fish Toxicity Rainbow Trout AB 00023616, 00028550, 00028553, 00031524,

40098001, 43774704

72-2 Invertebrate Toxicity AB 00028549, 00028555, 00031526, 40098001,

43774703(2), 43774705(2)

72-3 Estuarine/Marine Toxicity - Fish AB 44524301

72-3 Estuarine/Marine Toxicity -

Mollusk

AB 44524303

72-3 Estuarine/Marine Toxicity -

Shrimp

AB 44524302

72-4A Early Life Stage Fish AB 43862601
Data Supporting Guideline Requirements for the Reregistration of Alachlor

REQUIREMENT USE PATTERN CITATION(S)

219

72-4B Life Cycle Invertebrate AB 43774707

122-2 Aquatic Plant Phytotoxicity AB Data Gap

 for alachlor (data in review)

 for alachlor ESA

123-1A Seed Germination/Seedling

Emergence

AB 42468701

123-1B Vegetative Vigor AB 42468601

123-2 Aquatic Plant Growth AB 42763801

141-1 Honey Bee Acute Contact AB 00074486, 00028772

TOXICOLOGY

870.1100 Acute Oral Toxicity - Rat all 00139383, 42701501(1)

870.1200 Acute Dermal Toxicity -

Rabbit/Rat

all 00139384

870.1300 Acute Inhalation Toxicity - Rat all 00109561

870.2400 Primary Eye Irritation - Rabbit all 00139385

870.2500 Primary Dermal Irritation -

Rabbit

all 00139386

870.2600 Dermal Sensitization - Guinea Pig all 00161728

870.3100 90-Day Feeding - Rodent AB 00023658, 42863701(1)

870.3150 90-Day Feeding - Non-rodent AB 00087479

870.3200 21-Day Dermal - Rabbit/Rat AB 00147328

870.4100

870.4200

870.4300

Chronic Toxicity and

Carcinogenicity - Rodent

AB 00139021, 00075709, 00091050, 00141060,

43507601
Data Supporting Guideline Requirements for the Reregistration of Alachlor

REQUIREMENT USE PATTERN CITATION(S)

220

870.4100 Chronic Toxicity and

Carcinogenicity - Non-Rodent

AB 00148923

870.3700 Developmental Toxicity - Rat AB 00043645, 43908101(1)

870.3700 Developmental Toxicity - Rabbit AB 40579402

870.3800 2-Generation Reproduction - Rat AB 00075062

870.5300

870.5385

870.5500

870.5550

870.5575

Mutagenicity AB 00109563, 00141061, 00141062, 00148921,

00155389(2), 00155391(2), 00155392(2),

00155393(2), 00151394(2), 0015395(2),

00151396(2), 00151397(2),

00151398(1),00151399(2), 42651301, 42651301(2),

42651302, 42651303, 43889403(1), 44032103

870.7485 General Metabolism AB 000132045, 43889404(1), 40000901, 42651306,

42852107, 42651308, 42852108, 42651305,

42852106

870.7600 Dermal Penetration AB 00149403, 00149404, 00149405

Special Studies AB 00023611, 00023612, 00149402, 00149403,

00149404, 00149405, 00150089, 00154238,

00159365, 00159364, 42852102, 43590002,

43889401(1), 43889402(1), 42651307, 42651310,

42852109, 42931101, 42651304, 42651309,

42651311, 42651312, 42651314, 42651318,

42852103, 42852104, 42852105, 42852110,

42852111, 42957201, 43267501, 43369201,

43482301, 43504101, 43507401, 43641603,

43706001, 43590001, 43641604, 43641602,

43729502, 43750801, 43729503, 43729501,

43878501
Data Supporting Guideline Requirements for the Reregistration of Alachlor

REQUIREMENT USE PATTERN CITATION(S)

221

OCCUPATIONAL/RESIDENTIAL EXPOSURE

132-1A Foliar Residue Dissipation

132-1B Soil Residue Dissipation

133-3 Dermal Passive Dosimetry

Exposure

133-4 Inhalation Passive Dosimetry

Exposure

231 Estimation of Dermal Exposure at

Outdoor Sites

AB Data Gap - Impregnation of Dry Bulk

Fertilizer 

232 Estimation of Inhalation Exposure

at Outdoor Sites

AB Data Gap - Impregnation of Dry Bulk

Fertilizer

233 Estimation of Dermal Exposure at

Indoor Sites

AB Data Gap - Impregnation of Dry Bulk

Fertilizer

234 Estimation of Inhalation Exposure

at Indoor Sites

AB Data Gap - Impregnation of Dry Bulk

Fertilizer

ENVIRONMENTAL FATE

161-1 Hydrolysis AB 00134327

161-2 Photodegradation - Water AB 00023012

162-1 Aerobic Soil Metabolism AB 00023014, 00101531, 00134327

163-1 Leaching/Adsorption and 

Desorption

AB 00027139, 00027140, 00078301, 00134327,

42485703(3), 42485704(3), 44405301(1)

164-1 Terrestrial Field Dissipation AB 42528001, 42528002, 42528003, 42528004,

43774701 
Data Supporting Guideline Requirements for the Reregistration of Alachlor

REQUIREMENT USE PATTERN CITATION(S)

222

201-1 Droplet Size Spectrum AB Reserved - Spray Drift Task Force (data in

review)

202-1 Drift Field Evaluation AB Reserved - Spray Drift Task Force (data in

review)

Special Studies Monitoring Data AB 41400001, 41400002, 41400003, 41400004,

44592401, 40265901, 00158911, 41065205,

441095503

RESIDUE CHEMISTRY

165-1 Rotational Crop (Confined) AB 42395301, 42395302

165-2 Rotational Crop (Field) AB 43442001

Data Gap (Data in Review)

171-4A Nature of Residue - Plants AB 00026221, 00081314, 00131424

171-4B Nature of Residue - Livestock AB 00137777, 00137778, 00147472,

00147473, 40393901, 40394001, 42594901,

42594902, 42594903, 42594904

171-4C/D Residue Analytical Method -

Plants and Animals

AB 00023663, PP#9F0740, 00093160, 00148285,

00149999, 00152197, 00154237, 00154332,

00155732, 00159793, 00159796, 00162939,

40039901, 40040301, 40040401, 40271801,

40271802, 40529201, 40558001, 40820601,

41916001, 41949601, 42086001, 42192501,

42286701, 42286702, 42308701, 42349101,

43140001

171-4C/D Residue Analytical Method -

Water 

AB Data Gap
Data Supporting Guideline Requirements for the Reregistration of Alachlor

REQUIREMENT USE PATTERN CITATION(S)

223

171-4E Storage Stability AB 00149406, 00150090, 00152198, 00152868,

00154237, 40491101, 40628301, 40946901,

42239501

171-4J Magnitude of Residues -

Meat/Milk/Poultry/Egg

AB 00149406, 00150090, 00152198, 00152868

171-4K Crop Field Trials 

Root and Tuber Vegetable Group

Potatoes tolerance revoked 

Legume Vegetables (Dry

Succulent) Group

-Beans, succulent and dry AB 00022988, 00026995, 00035389, 00035390,

00035391, PP#3F1406, 00147475, 40039901,

40040301, 40189701, 40341201, 41083801

-Peas, succulent and dried tolerance revoked 

-soybeans AB 00023664, 00025262, 00148285, 00152197,

40511901, 41862901, 41916301, 42309001,

42313301, 42348901, 42349101, PP#3F2313

Foliage of Legume Vegetables

Group

-beans, vines and hay AB 00022988, 00026995, 00035389, 00035390,

00035391, PP#3F1406, 00147475, 40039901,

40040301, 40189701, 40341201, 41083801,

PP#3F4179

-peas, vines and hay tolerance revoked

-soybeans, forage and hay AB 00023664, 00025262, 00152197, 41140801,

42348901, 42349101, PP#9F3776
Data Supporting Guideline Requirements for the Reregistration of Alachlor

REQUIREMENT USE PATTERN CITATION(S)

224

Cereal Grains Group

-corn, field, grain AB 00023665, 00035395, 00035399, PP#9F0740,

00152197, 00155732, 00159793, 40502101,

42348902, 42349101, 42741601

-corn, sweet AB 00023665, 00035395, 00035399, PP#9F0470,

00152197, 00155732, 00159793, 40502101,

40662601, 42929901, 42934401

-sorghum, grain AB 00028556, 00028557, 00028558, 00068044,

00068045, PP#0F2338, 00159796, 40271801,

PP#8F3671

Forage, Fodder and Straw of

Cereal Grains Group

-corn, field, forage and fodder AB 00023665, 00035395, 00035399, PP#9F0740,

00152197, 00159793, 40502101, 42348902,

42349101, PP#0F2348

-corn, sweet, forage AB 00023665, 00035395, 00035399, PP#9F0740,

00152197, 00159793, 40502101, 40662601,

42741601, 42929901, PP#0F2348

-sorghum, forage and fodder AB 00068044, 00068045, 00159796, 40271801,

40511201, PP#8F3671

Miscelllaneous Commodities

-Cotton AB tolerance revoked 

-peanuts AB 00024526, 00081311, PP#7G2002, 00152199,

00159936, 40511301, 40820601, 42971701,

PP#0F2313, FAP#1H5612

-sunflower AB tolerance revoked 
Data Supporting Guideline Requirements for the Reregistration of Alachlor

REQUIREMENT USE PATTERN CITATION(S)

225

171-4L Processed Food

-corn, field AB 00162939, 40788201

-peanuts AB PP#0F2313/FAP#1H5612, 00162937,

40040401, 41856301, 42302001

-sorghum AB 40271802

-soybeans AB 00148285, 00152197, 00154239, 00154240,

40947101, 41862901, 41916301

-sunflower AB 00147471, 40040101, 40314601, 40529201

171-5 Reduction of Residues AB 40330301, 40820601, 40820701, 42158601,

42276701, 42300701, 

42309001

Footnotes:

(1). test material alachlor ESA

(2). test material other metabolites

of alachlor 

(3). Test material metabolites of

propachlor
226

c.Citations Considered to be Part of the Data Base Supporting the Reregistration Decision
227

GUIDE TO APPENDIX C

1. CONTENTS OF BIBLIOGRAPHY. This bibliography contains citations of all studies considered

relevant by EPA in arriving at the positions and conclusions stated elsewhere in the Reregistration

Eligibility Document. Primary sources for studies in this bibliography have been the body of data

submitted to EPA and its predecessor agencies in support of past regulatory decisions. Selections

from other sources including the published literature, in those instances where they have been

considered, are included.

2. UNITS OF ENTRY. The unit of entry in this bibliography is called a "study". In the case of published

materials, this corresponds closely to an article. In the case of unpublished materials submitted to the

Agency, the Agency has sought to identify documents at a level parallel to the published article from

within the typically larger volumes in which they were submitted. The resulting "studies" generally

have a distinct title (or at least a single subject), can stand alone for purposes of review and can be

described with a conventional bibliographic citation. The Agency has also attempted to unite basic

documents and commentaries upon them, treating them as a single study.

3. IDENTIFICATION OF ENTRIES. The entries in this bibliography are sorted numerically by Master

Record Identifier, or "MRID number". This number is unique to the citation, and should be used

whenever a specific reference is required. It is not related to the six-digit "Accession Number" which

has been used to identify volumes of submitted studies (see paragraph 4(d)(4) below for further

explanation). In a few cases, entries added to the bibliography late in the review may be preceded by a

nine character temporary identifier. These entries are listed after all MRID entries. This temporary

identifying number is also to be used whenever specific reference is needed.

4. FORM OF ENTRY. In addition to the Master Record Identifier (MRID), each entry consists of a

citation containing standard elements followed, in the case of material submitted to EPA, by a

description of the earliest known submission. Bibliographic conventions used reflect the standard of

the American National Standards Institute (ANSI), expanded to provide for certain special needs.

a Author. Whenever the author could confidently be identified, the Agency has chosen to show a

personal author. When no individual was identified, the Agency has shown an identifiable laboratory

or testing facility as the author. When no author or laboratory could be identified, the Agency has

shown the first submitter as the author.

b. Document date. The date of the study is taken directly from the document. When the date is followed

by a question mark, the bibliographer has deduced the date from the evidence contained in the

document. When the date appears as (19??), the Agency was unable to determine or estimate the date

of the document.

c. Title. In some cases, it has been necessary for the Agency bibliographers to create or enhance a

document title. Any such editorial insertions are contained between square brackets.

d. Trailing parentheses. For studies submitted to the Agency in the past, the trailing parentheses include

(in addition to any self-explanatory text) the following elements describing the earliest known

submission:

(1) Submission date. The date of the earliest known submission appears immediately following the

word "received."
228

(2) Administrative number. The next element immediately following the word "under" is the

registration number, experimental use permit number, petition number, or other administrative

number associated with the earliest known submission.

(3) Submitter. The third element is the submitter. When authorship is defaulted to the submitter,

this element is omitted.

(4) Volume Identification (Accession Numbers). The final element in the trailing parentheses

identifies the EPA accession number of the volume in which the original submission of the

study appears. The six-digit accession number follows the symbol "CDL," which stands for

"Company Data Library." This accession number is in turn followed by an alphabetic suffix

which shows the relative position of the study within the volume.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

229

00022998 Monsanto Company (1968) Full Reports of Investigations Made with Respect to the Safety of

the Pesticide Chemical: [Lasso]. Summary of studies 004026-C through 004026-E. 

(Unpublished study received Dec 20, 1968 under 524-287; CDL:004026-B)

00023012 Sutherland, M.L.; Curtis, T.G.; Darlington, W.A.; et al. (1972) Final Report on Lasso and the

Environment: Part 4: Photolysis of Lasso on Soil and in Water: Agricultural Research Report

No. 262. (Unpublished study received Jun 29, 1973 under 3F1372; submitted by Monsanto

Co., Washington, D.C.; CDL:093660-L)

00023014 Sutherland, M.L.; Curtis, T.G.; Darlington, W.A.; et al. (1972) Final Report on Lasso and the

Environment: Part 6: Soil Dissipation of Lasso: Agricultural Research Report No. 264. 

(Unpublished study received Jun 29, 1973 under 3F1372; submitted by Monsanto Co.,

Washington, D.C.; CDL:093660-N)

00023611 Shelanski, M.V. (1968) To Determine Whether or Not Repeated Contact with the Test

Material under Controlled Conditions Presents a Hazard to the Skin of Human Volunteers:

Project No. SH-67-9. (Unpublished study received Aug 16, 1978 under 524-285; prepared by

Industrial Biology Research and Testing Laboratories, Inc., submitted by Monsanto Co.,

Washington, D.C.; CDL:234629-B)

00023612 Shelanski, M.V. (1968) To Determine If the Test Material Is Capable of Irritating the Skin of

Humans under Controlled Test Conditions: IBT: 1978 under 524-285; prepared by Industrial

Biology Research and Testing Laboratories, Inc., submitted by Monsanto Co., Washington,

D.C.; CDL:234629-C)

00023615 Thompson, C.M.; Forbis, A.D.; McAllister, W.A. (1978) Acute Toxicity of Technical Alachlor

(AB-78-166) to Bluegill Sunfish (Lepomis macrochirus). (Unpublished study received Aug 16,

1978 under 524-285; prepared by Analytical Biochemistry Laboratories, Inc., submitted by

Monsanto Co., Washington, D.C.; CDL: 234628-C)

00023616 Forbis, A.D.; McAllister, W.A. (1978) Acute Toxicity of Technical Alachlor to Rainbow Trout

(Salmo gairdneri). (Unpublished study received Aug 16, 1978 under 524-285; prepared by

Analytical Biochemistry Laboratories, Inc., submitted by Monsanto Co., Washington, D.C.;

CDL:234628-D)

00023658 Wolf, C. (1966) Report to Monsanto Company: 90-Day Subacute Oral Toxicity of

CP50144--Albino Rats: IBT No. B4477. (Unpublished study received Dec 1, 1966; prepared

by Industrial Bio-Test Laboratories, Inc., submitted by Monsanto Co., Washington, D.C.;

CDL:090813-C)

00023663 Monsanto Company (19??) Chemical Analytical Residue Methods. Three undated methods. 

(Unpublished study received Dec 1, 1966 under 7F0622; CDL:090813-H)
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

230

00023664 Monsanto Company (1966) Results of Analysis of Field Treated Soybeans. (Unpublished

study received Dec 1, 1966 under 7F0622; CDL:090813-I)

00023665 Monsanto Company (1966) Results of Analysis of Field Treated Corn. (Unpublished study

received Dec 1, 1966 under 7F0622; CDL: 090813-J)

00024526 Monsanto Company (1971) Chemical Residue Studies on Peanuts, Peanut Hulls and Peanut

Vines. (Unpublished study received Mar 5, 1975 under 3F1334; CDL:093569-B)

00025262 Monsanto Company (1966) Results of Analysis of Field Treated Soybeans: [Alachlor]. 

(Unpublished study received Sep 11, 1968 under 9F0740; CDL:091280-B)

00026221 Monsanto Company (19??) Summary on Metabolism of CP 50144 in Soybeans and Corn. 

(Unpublished study received Dec 1, 1966 under 7F0622; CDL:090813-M)

00026995 Monsanto Company (1969) Reasonable Grounds in Support of the Petition for Residue

Tolerance: [Lasso]. (Unpublished study received on unknown date under 2G1176;

CDL:095433-F)

00027139 Weidner, C.W. (1974) Degradation in Groundwater and Mobility of Herbicides. Master's

thesis, Univ. of Nebraska, Dept. of Agronomy. (Unpublished study received Jul 19, 1978

under 201-403; submitted by Shell Chemical Co., Washington, D.C.; CDL:234472-O)

00027140 Lavy, T.L. (1974) Mobility and Deactivation of Herbicides in SoilWater Systems: Project

A-024-NEB. (Available from: National Technical Information Service, Springfield, VA:

PB-238 632; unpublished study received Jul 19, 1978 under 201-403; prepared by Univ. of

Nebraska, Water Resources Research Institute, submitted by Shell Chemical Co., Washington,

D.C.; CDL:234472-P)

00028549 McAllister, W.A.; Forbis, A.D. (1978) Acute Toxicity of Technical Alachlor (AB-78-200) to

Daphnia magna. (Unpublished study received Dec 28, 1979 under 524-285; prepared by

Analytical Bio Chemistry Laboratories, Inc., submitted by Monsanto Co., Washington, D.C.;

CDL:241535-A)

00028550 Thompson, C.M.; Forbis, A.D. (1978) Acute Toxicity of Lasso (MCB/ Cg) (AB-78-111) to

Rainbow Trout (Salmo gairdneri). (Unpublished study received Dec 28, 1979 under 524-285;

prepared by Analytical Bio Chemistry Laboratories, Inc., submitted by Monsanto Co.,

Washington, D.C.; CDL:241535-B)

00028551 Thompson, C.M.; Forbis, A.D. (1978) Acute Toxicity of Lasso (MCB/ Cg) (AB-78-111) to

Bluegill Sunfish (Lepomis macrochirus). (Unpublished study received Dec 28, 1979 under

524-285; prepared by Analytical Bio Chemistry Laboratories, Inc., submitted by Monsanto

Co., Washington, D.C.; CDL: 241535-C)
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

231

00028553 Thompson, C.M.; Forbis, A.D. (1978) Acute Toxicity of Lasso EC (MCB) (AB-78-167B) to

Rainbow Trout (Salmo gairdneri). (Unpublished study received Dec 28, 1979 under 524-285;

prepared by Analytical Bio Chemistry Laboratories, Inc., submitted by Monsanto Co.,

Washington, D.C.; CDL:241535-E)

00028554 Thompson, C.M.; Forbis, A.D. (1978) Acute Toxicity of Lasso EC (MCB) (AB-78-167) to

Bluegill Sunfish (Lepomis macrochirus). (Unpublished study received Dec 28, 1979 under

524-285; prepared by Analytical Bio Chemistry Laboratories, Inc., submitted by Monsanto

Co., Washington, D.C.; CDL:241535-F)

00028555 McAllister, W.A.; Forbis, A.D. (1978) Acute Toxicity of Lasso EC (MCB) (AB-78-167) to

Daphnia magna. (Unpublished study received Dec 28, 1979 under 524-285; prepared by

Analytical Bio Chemistry Laboratories, Inc., submitted by Monsanto Co., Washington, D.C.;

CDL:241535-G)

00028556 Lauer, R.; Arras, D.D.; Stranz, J.L.; et al. (1979) Residues of Alachlor and Atrazine in Field

Treated Sorghum following Preor Postemergent Applications with Lasso(R) or a Lasso(R) +

Atrazine Tank Mix: Report No. MSL-1033. Rev. (Unpublished study received Mar 25, 1980

under 524-285; prepared in cooperation with ABC Laboratories, Inc., submitted by Monsanto

Co., Washington, D.C.; CDL:099326-A)

00028557 Monsanto Company (19??) Analytical Residue Method for Alachlor in Sorghum Forage,

Fodder and Grain. Two undated methods. (Unpublished study received Mar 25, 1980 under

524-285; CDL: 099326-B)

00028558 Monsanto Company (19??) Reasonable Grounds in Support of the Request: [Lasso]. 

(Unpublished study received Mar 25, 1980 under 524-285; CDL:099326-C)

00031524 Thompson, C.M.; Forbis, A.D.; Oleson, F.B.; et al. (1979) Acute Toxicity of Lasso(R)

NF-79-WB (AB-79-068) to Rainbow Trout (Salmo gairdneri): Static Acute Bioassay Report #

24007. (Unpublished study received Jan 17, 1980 under 524-EX-49; prepared in cooperation

with Analytical Bio Chemistry Laboratories, Inc., submitted by Monsanto Co., Washington,

D.C.; CDL:241619-E)

00031525 Thompson, C.M.; McAllister, W.A.; Oleson, F.B.; et al. (1979) Acute Toxicity of Lasso(R)

NF-79-WB (AB-79-069) to Bluegill Sunfish (Lepomis macrochirus): Static Acute Bioassay

Report # 24008. (Unpublished study received Jan 17, 1980 under 524-EX-49; prepared in

cooperation with Analytical Bio-Chemistry Laboratories, Inc., submitted by Monsanto Co.,

Washington, D.C.; CDL:241619-F)

00031526 Thompson, C.M.; Forbis, A.D.; Oleson, F.B. (1979) Acute Toxicity of Lasso(R) NF-79-WB

(AB-79-070) to Daphnia magna: Static Acute Bioassay Report # 24009. (Unpublished study
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

232

received Jan 17, 1980 under 524-EX-49; prepared in cooperation with Analytical Bio

Chemistry Laboratories, Inc., submitted by Monsanto Co., Washington, D.C.; CDL:241619-G)

00035389 Monsanto Company (1969) [Residues of Lasso in Green Beans]. (Unpublished study received

on unknown date under 1F1009; CDL: 091749-I)

00035390 Monsanto Company (1969) [Residues of Lasso in Lima Beans]. (Unpublished study received

on unknown date under 1F1009; CDL: 091749-J)

00035391 Monsanto Company (1969) [Residues of Lasso in Kidney Beans]. (Unpublished study

received on unknown date under 1F1009; CDL: 091749-K)

00035395 Monsanto Company (1969) [Residues of Lasso and Atrazine in Corn]. (Unpublished study

received on unknown date under 1F1009; CDL: 091749-O)

00035399 Monsanto Company (1969) [Residues of Lasso in Corn]. (Unpublished study received on

unknown date under 1F1009; CDL:091749-T)

00043645 Rodwell, D.E.; Tasker, E.J. (1980) Teratology Study in Rats: IRDC No. 401-058; IR-79-020. 

(Unpublished study including submitter summary, received Oct 16, 1980 under 524-285;

prepared by International Research and Development Corp., submitted by Monsanto Co.,

Washington, D.C.; CDL:243506-A)

00068044 Wilson, G.R.; Dubelman, S. (1981) Residues of Alachlor in Sorghum Forage, Stover, and

Grain following Preemergent Treatment with Alachlor in Tank-mix Combinations with

Propazine and Bifenox: Report No. MSL-1577. Final rept. Includes undated methods

entitled: Analytical residue method for alachlor in sorghum forage, stover, and grain; Analytical

residue method for bifenox (Modown) in sorghum; Analytical residue method for propazine in

sorghum forage, stover, and grain. (Unpublished study received May 27, 1981 under 524-285;

prepared by ABC Laboratories, Inc., submitted by Monsanto Co., Washington, D.C.;

CDL:245225-A)

00068045 Monsanto Company (19??) Reasonable Grounds in Support of the Request: [Lasso]. 

(Unpublished study received May 27, 1981 under 524-285; CDL:245225-B)

00075062 Schroeder, R.E.; Hogan, G.K.; Smock, M.E.; et al. (1981) A Three Generation Reproduction

Study in Rats with Alachlor: Project No. 77-2066. Final rept. (Unpublished study received Jul

10, 1981 under 524-285; prepared by Bio/dynamics, Inc., submitted by Monsanto Co.,

Washington, D.C.; CDL:070177-A)

00075709 Daly, I.W.; Hogan, G.K.; Plutnick, R.; et al. (1981) An Eighteen Month Chronic Feeding

Study of Alachlor in Mice: Project No. 772064. Final rept. (Unpublished study received Jul 1,
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

233

1981 under 524-285; prepared by Bio/dynamics, Inc., submitted by Monsanto Co.,

Washington, D.C.; CDL:070168-A; 070169)

00074486 Atkins, E.L.; Kellum, D. (1980) Effect of Pesticides on Apiculture: Maximizing the

Effectiveness of Honey Bees as Pollinators: Project No. 1499. 1980 annual report

(Unpublished study received June 8, 1981, under 2141-159; prepared by Univ. Of California--

Riverside, Citrus Research Center and Agricultural Experiment Station, Deptmant of

Entomology, submitted by American Cyanamid Cl., Princeton, N.J.: CDL 070148-G

00078301 Guth, J.A. (1975) CGA-24705 Leaching Model Study with the Herbicide CGA-24705 in Four

Standard Soils: Nr. SPR 3/75. (Unpublished study received Jul 23, 1981 under 100-587;

prepared by CibaGeigy, Ltd., Switzerland, submitted by Ciba-Geigy Corp., Greensboro, N.C.;

CDL:245628-E)

00079523 Fink, R.; Beavers, J.B.; Brown, R.; et al. (1979) Final Report: Acute Oral LD50--Bobwhite

Quail: Project No. 139-179. (Unpublished study received June 2, 1981 under 524-285;

prepared by Wildlife International, Ltd., submitted by Monsanto Co., Washington, D.C.;

CDL:245260-A)

00081311 Monsanto Company (1968) Results of Analysis of Field Treated Peanuts. (Unpublished study

received Jan 22, 1969 under 9F0776; CDL:091335-B)

00081314 Monsanto Company (19??) Summary on Metabolism of CP 50144 (Lasso) in Cotton and

Peanuts. (Unpublished study received Jan 22, 1969 under 9F0776; CDL:091335-E)

00087479 Ahmed, F.E.; Tegeris, A.S.; Underwood, P.C.; et al. (1981) Alachlor: Six Month Study in the

Dog: Testing Facility's Report No. 7952; Sponsor's Report No. PR-80-015. (Unpublished

study, including submitter summary, received Dec 1, 1981 under 524-316; prepared by

Pharmacopathics Research Laboratories, Inc., submitted by Monsanto Co., Washington, D.C.;

CDL:246292-A; 246293)

00091050 Daly, I.W.; McCandless, J.B.; Jonassen, H.; et al. (1981) A Chronic Feeding Study of Alachlor

in Rats: Project No. 77-2065. Final rept. (Unpublished study received Jan 5, 1982 under

524-285; prepared by Bio/dynamics, Inc., submitted by Monsanto Co., Washington, D.C.;

CDL:070586-A; 070587; 070588; 070589; 070590)

00093160 Monsanto Company (19??) Analytical Method for Lasso. (Unpublished study received Jul 1,

1970 under 1F1009; CDL:093319-C)

00101531 Banduhn, M.; Livingston, C.; Kloek, J.; et al. (1981) Comparative Environmental Fate and

Crop Uptake Studies of Encapsulated and Unencapsulated Alachlor: Report No. MSL-2070. 

(Unpublished study received May 10, 1982 under 524-344; submitted by Monsanto Co.,

Washington, DC; CDL:070841-B)
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

234

00106553 Fink, R.; Beavers, J.; Joiner, G.; et al. (1980) Final Report: Eight-day Dietary LC50--Bobwhite

Quail: [Lasso N]: Project No. 139-185. (Unpublished study received May 10, 1982 under

524-344; prepared by Wildlife International Ltd., submitted by Monsanto Co., Washington,

DC; CDL:070839-J)

00106554 Fink, R.; Beavers, J.; Joiner, G.; et al. (1980) Final Report: Eight-day Dietary LC50--Mallard

Duck: [Lasso N]: Project No. 139-186. (Unpublished study received May 10, 1982 under

524-344; prepared by Wildlife Interantional Ltd., submitted by Monsanto Co., Washington,

DC; CDL:070839-K)

00107908 Fink, R.; Beavers, J.; Joiner, G.; et al. (1980) Final Report: Acute Oral LD50--Bobwhite Quail:

[Lasso N]: Project No. 139-187. (Unpublished study received May 10, 1982 under 524-344;

prepared by Wildlife International Ltd., submitted by Monsanto Co., Washington, DC;

CDL:070839-I)

00109561 Eschbach, J.; Hogan, G.; Melcon, M.; et al. (1982) An Acute Inhalation Toxicity Study of

Alachlor Technical in the Rat: Project No. 81-7502; BD-81-183. (Unpublished study received

Aug 11, 1982 under 524-285; prepared by Bio/dynamics, Inc., submitted by Monsanto Co.,

Washington, DC; CDL:248053-A)

00109563 Shirasu, Y.; Moriya, M.; Ohta, T. (1980) Alachlor: Microbial Mutagenicity Study:

ET-80-0101. (Unpublished study received Aug 11, 1982 under 524-285; prepared by Institute

of Environmental Toxicology, Japan, submitted by Monsanto Co., Washington, DC;

CDL:248053-C)

00131424 Monsanto Co. (1983) Plant Metabolism Data: [Lasso in Soybeans and Corn]: R.D. No. 489;

Special Report MSL-3132. (Compilation; unpublished study received Oct 3, 1983 under

524-285; CDL: 251375-A)

00132045 Wilson, A.; Dietrich, M.; Folk, R. (1983) Rat Metabolism Data: [Lasso and Others]: R.D. No.

493; Special Report MSL-3198. Final rept. (Unpublished study received Oct 21, 1983 under

524285; submitted by Monsanto Co., Washington, DC; CDL:251543-A; 251544)

00134327 Suba, L.; Pearson, D.; Malik, J. (1979) The Environmental Studies of Alachlor: R.D. #258:

Report Nos. MSL-0860, MSL-0861. Final rept. (Unpublished study received Oct 11, 1979

under 524-285; submitted by Monsanto Co., Washington, DC; CDL:241135-A; 241136)

00137777 Shaffer, S.; Burnett, J.; Williams, M.; et al. (1984) Metabolism Study of 14C-labeled Plant

Metabolites of Alachlor in Laying Hens: ABC Laboratory No. 30828. Final rept. 

(Unpublished study received Mar 30, 1984 under 524-285; prepared by Analytical

BioChemistry Laboratories, Inc., submitted by Monsanto Co., Washington, DC;

CDL:252792-A)
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

235

00137778 Lawman, K.; Predmore, L.; Burnett, J.; et al. (1984) Metabolism of Synthetic 14C-labeled

Plant Metabolites of Alachlor in Lactating Goats: ABC Laboratory No. 30829. Final rept. 

(Unpublished study received Mar 30, 1984 under 524-285; prepared by Analytical

Bio-Chemistry Laboratories, Inc. and Univ. of Missouri, Sinclair Comparative Medicine

Research Farm, submitted by Monsanto Co., Washington, DC; CDL:252793-A)

00139021 Stout, L.; Ribelin, W.; Thake, D.; et al. (1984) Chronic Study of Alachlor in Rats and a Risk

Assessment: Study No. 800218. (Unpublished study received Feb 28, 1984 under 524-285;

submitted by Monsanto Co., Washington, DC; CDL:252496-A; 252497)

00139383 Heenehan, P.R.; Rinehart, W.E.; Braun, W.G. (1979) Acute Oral Toxicity Study in Rats;

Compound: Alachlor (Technical): Project No. 4899-77; BD-77-433. Rev. (Unpublished

study, including letters dated Aug 6, 1979 from W.E. Rinehart to George Levinskas; Aug 31,

1979 from F.B. Oleson to W.D. Carpenter, received Oct 16, 1979 under 524-285; prepared by

Bio/dynamics, Inc., submitted by Monsanto Co., Washington, D.C.; CDL:241273-N)

00139384 Auletta, C.S.; Rinehart, W.E. (1979) Acute Dermal Toxicity Study in Rabbits: Project No.

4900-77; BD-77-433. Rev. (Unpublished study, including letters dated Aug 6, 1979 from

W.E. Rinehart to George Levinskas; Aug 28, 1979 from F.B. Oleson to W.D. Carpenter,

received Oct 16, 1979 under 524-285; prepared by Monsanto Co., Washington, D.C.;

CDL:241273-O)

00139385 Heenehan, P.R.; Rinehart, W.E.; Braun, W.G. (1979) Rabbit Eye Irritation Study; Compound:

Alachlor (Technical): Project No. 4901-77; BDN-77-433. Rev. (Unpublished study, including 

letters dated Aug 6, 1979 from W.E. Rinehart to George Levinskas; Aug 28, 1979 from F.B.

Oleson to W.D. Carpenter, received Oct 16, 1979 under 524-285; prepared by Bio/dynamics,

Inc., submitted by Monsanto Co., WAshington, D.C.; CDL:241273-P)

00139386 Heenehan, P.R.; Braun, W.G.; Rinehart, W.E. (1979) Primary Dermal Irritation Study in

Rabbits; Compound: Alachlor (Tecnical): Project No. 4902-77; BDN-77-433. Rev. 

(Unpublished study, including letters dated Aug 6, 1979 from W.E. Rinehart to George

Levinskas; Aug 28, 1979 from F.B. Oleson to W.D. Carpenter, received Oct 16, 1979 under

524-285; prepared by Bio/ dynamics, Inc., submitted by Monsanto Co., Washington, D.C.;

CDL:241273-Q)

00141060 Stout, L. (1984) A Special Chronic Feeding Study With Alachlor in Long-Evans Rats: DMEH

Project No. ML-80-224. Unpublished study prepared by Monsato Co 902 p.

00141061 Mirsalis, J.; Tyson, C. (1984) Evaluation of the Potential of Alachlor To Induce Unscheduled

DNA Synthesis in the in-vivo-in vitro Hepatocyte DNA Repair Assay: Final Report: SRI LSC

83-201: Project No. 6642. Unpublished study prepared by SRI International. 31 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

236

00141062 Cortina, T. (1984) In vivo Bone Marrow Chromosome Study in Rats: AlachlorL: Final Report:

Project No: 241-154. Unpublished study prepared by Hazleton Laboratories America, Inc. 77

p.

00146114 Muench, S., comp. (1985) Product Chemistry Data to Support the Continued Registration of

Alachlor...R.D. No. 621; Special Report MSL-4732. Unpublished compilation prepared by

Monsanto Agricultural Products Co. 713 p.

00147328 Johnson, D. (1985) 21-day Dermal Toxicity Study in Rabbits: Lasso MCB C9 IR-83-081:

401-211. Unpublished study prepared by International Research and Development Corp. 178

p.

00147471 Muench, S. (1985) Residue Analysis of Sunflowers following a Preemergent Treatment and

Corn following a Directed Post Emergent Treatment of Lasso: Special Report MSL-4621. 

Unpublished study prepared by Monsanto Co. 146 p.

00147472 Yalamanchili, G.; Oppenhuizen, M.; Klemm, G. (1984) Metabolism of Synthetic Carbon

14-labelled Plant Metabolites of Alachlor in Lactating Goats: Part II: Identification,

Characterization, and Quantitation of Metabolites in Goat Excreta: Report No. MSL3886. 

Unpublished study prepared by Monsanto Co. 68 p.

00147473 Carr, K.; Livingston, C. (1984) Metabolism of Synthetic Carbon 14 -labelled Plant Metabolites

of Alachlor in Laying Hens: Part II: Identification Characterization, and Quantitation of

Metabolites in Eggs, Tissues, and Excreta (Part I, MSL-3465): Report No. MSL-4230. 

Unpublished study prepared by Monsanto Co. 94 p.

00147475 Muench, S, (1985) Residues of Alachlor in Dry Bean Forage, Hay, Pods, and Seed following a

Pre-plant Treatment with Lasso ME Herbicide: Special Report MSL-4622. Unpublished study

prepared by Monsanto Co. 89 p.

00147476 Muench, S. (1985) Product Chemistry Data to Support the Continued Registrations of Lasso,

Lasso EC, Lasso II and Lasso/Atrazine Flowable Herbicides: Special Report MSL-4623. 

Unpublished study prepared by Monsanto Co. 178 p.

00148285 Graham, J.; Marshall, M.; Arras, D.; et al. (1985) Alachlor Residues from Two Metabolite

Classes in Soybeans and Soybean Fractions: Report No. MSL-4535. Unpublished study

prepared by Monsanto Co. 250 p.

00148921 Godek, E. (1984) CHO/HGPRT Mammalian Cell Forward Gene Mutation Assay: Alachlor

Technical Lot #MDLT08-02B: Study No. PH 314-MO-006-83, PK-83-249. Unpublished

study prepared by Pharmakon International, Inc. 140 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

237

00148923 Naylor, M.; Ribelin, W.; Thake, D.; et al. (1984) Chronic Study of Alachlor Administered by

Gelatin Capsule to Dogs: Project No. ML-82-279: Study No. 820165. Unpublished study

prepared by Monsanto Company. 439 p.

00149402 Fuhremann, T.; Sharp,D. (1985) Alachlor Applicator Exposure: Overview of Biomonitoring

Quantitative Exposure and Risk Assessment. Unpublised study prepared by Monsanto

Company. 13 p.

00149403 Johnson, D. (1984) Pharmacokinetic Study of Alachlor in Rhesus Monkeys following

Intravenous Administration: Project No. 401-296: Study No. IR-84-244. Unpublished study

prepared by International Research and Development Corp. 90 p.

00149404 Johnson, D. (1984) Percutaneous Absorption Study of Lasso MCB/C9 in Rhesus Monkeys:

Study No. 401-298. Unpublished study prepared by International Research and Development

Corp. Monsanto Project No. IR-84-246. 97 p.

00149405 Johnson, D. (1985) Percutaneous Absorption Study of Lasso ME in Rhesus Monkeys:

Amendment to the Final Report: Study No. 401-299. Unpublished study prepared by

International Research and Development Corp. Monsanto Project. No. IR-84-248. 91 p.

00149406 Miles, J. (1985) Contribution of Milk and Beef Products to Dietary Exposure and Risk

Assessment from the Use of Alachlor. Unpublished study prepared by Monsanto Company. 

12 p.

00149999 Muench, S., comp. (1985) Information to Support the Registration of Lasso: Methodology:

R.D. No. 592. Unpublished compilation. 18 p.

00150089 Klein, A.; Bade, T.; Smith, R.; et al. (1984) Urinary Excretion of Alachlor Residue following

Normal Application of Lasso or Lasso Micro-tech Herbicide under Commercial Conditions in

Indiana: Project No. 7118 and 7124: Report No. MSL-4207. Unpublished report prepared by

Monsanto Company. 88 p.

00150090 Nord, P.; Smith, J.; Allan, J.; et al. (1984) Residue Determination of Alachlor Metabolites in

Milk and Beef Tissues: Project No. 7124: Report No. MSL-4373. Unpublished report

prepared by Monsanto Company. 250 p.

00151394 Kier, L. (1975) Overview of Ames/Salmonella Assay Results on Five Compounds

Representative of Major Classes of Alachlor Metabolites. Unpublished study prepared by

Monsanto Environmental Health Laboratory. 3 p.

00151395 Kier, L. (1984) Ames/Salmonella Mutagenicity Assay of

N-((2,6diethyl)phenyl)-N-methoxymethyl-2-(hydroxy)acetamide: Final Report: DMEH Project
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

238

No. ML-84-036. Unpublished study prepared by Monsanto Co., Environmental Health

Laboratory. 22 p.

00151396 Kier, L. (1984) Ames/Salmonella Mutagenicity Assay of 2',6'-Diethyl-N-(methoxymethyl)

Oxanilic Acid, Sodium Salt: Final Report: DMEH Project No. ML-84-035. Unpublished study

prepared by Monsanto Co., Environmental Health Laboratory. 22 p.

00151397 Kier, L. (1984) Ames/Salmonella Mutagenicity Assay of

3-N-(2,6diethyl)phenyl-N-methoxymethyl-2-amino-2-oxoethanesulfinyl-2hydroxypropanoic

Acid, Sodium Salt: Final Report: DMEH Project No. ML-84-033. Unpublished study

prepared by Monsanto Co., Environmental Health Laboratory. 24 p.

00151398 Kier, L. (1984) Ames/Salmonella Mutagenicity Assay of N-(2,6-diethyl)

phenyl-N-methoxymethyl-2-amino-2-oxoethanesulfonic Acid, Sodium Salt: Final Report:

DMEH Project No. ML-84-037. Unpublished study prepared by Monsanto Co., Environmental

Health Laboratory. 26 p.

00151399 Kier, L. (1984) Ames/Salmonella Mutagenicity Assays of

N-2-ethyl6-(1-hydroxyethyl)phenyl-N-(methoxymethyl)-2-(methylsulfonyl) Acetamide,

Unpurified and Purified Samples and Impurity Fractions: Final Report: DMEH Project Nos.

ML-84-034, ML-84-101, ML-84-103. Unpublished study prepared by Monsanto Co.,

Environmental Health Laboratory. 43 p.

00152197 Arras, D.; Graham, J. (1984) Combined Residues of Alachlor from Two Classes of Metabolites

in Corn Forage, Stover and Grain, and Soybean Forage, Hay, Grain and Grain Fractions

following Preemergent Treatment with Lasso ME and Lasso EC Herbicides: Report No.

MSL-3603. Unpublished study prepared by Monsanto Co. 331 p.

00152198 Miles, J. (1985) Contribution of Swine and Poultry Products to Dietary Exposure and Risk

Assessment from the Use of Alachlor: An Overview. Unpublished study prepared by

Monsanto Co. 13 p.

00152199 Graham, J.; Arras, D. (1985) New Analytical Methodology for the Determination of Alachlor

Residues from Two Metabolite Classes in Peanut Forage, Vines, Hulls and Nutmeat: Report

No. MSL-3980. Unpublished study prepared by Monsanto Co. 146 p.

00152206 Klein, A.; Worley, J.; Rueppel, M. (1980) Determination of Contaminant in Acetanilide

Herbicide Products: Report No. MSL-1290. Unpublished study prepared by Monsanto Co. 46

p.

00152209 Brightwell, B.; Rueppel, M. (1976) Lasso and Ramrod: Physical Properties and Their

Relationship to the Environment: Report No. 443. Unpublished study prepared by Monsanto

Co. 14 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

239

00152210 Worley, J.; Dubelman, S. (1985) Determination of the Octanol/Water Partition Coefficient of

Alachlor: Report No. 4523. Unpublished study prepared by Monsanto Co. 34 p.

00152868 Nord, P.; Smith, R.; Adams, S.; et al. (1985) Residue Determination of Alachlor Metabolites in

Hog and Chicken Tissues. Unpublished compilation prepared by Monsanto Co. and others. 

433 p.

00154237 Muench, S.; comp. (1985) Stability of Acetochlor Residues in Crop Samples during Frozen

Storage: Special Report MSL-5165. Unpublished compilation prepared by Monsanto. 56 p.

00154238 Muench, S., comp. (1985) The Metabolism of Alachlor in Rhesus Monkeys. Part II.

Identification, Characterization, and Quantification of Alachlor and Its Metabolites after

Intravenous Administration to Monkeys: Special Report MSL-5117. Unpublished compilation

prepared by Monsanto. 77 p.

00154239 Marshall, M.; Graham, J. (1985) Alachlor Residues from Two Metabolite Classes in Soybeans

and Processed Soybean Oil Products: Rept. No. MSL-4942: Proj. No. 7124. Unpublished

study prepared by Monsanto Co. 151 p.

00154240 Marshall, M.; Graham, J. (1985) Alachlor Residues from Two Metabolite Classes in Soybeans

and Processed Soybean Protein Fractions: Rept. No. MSL-5123: Proj. No. 7124. Unpublished

study prepared by Monsanto Co. 181 p.

00154332 Nord, P.; Smith, R. (1984) Analytical Residue Method for the Determination of Alachlor

Metabolites Producing 2,6-Diethylaniline and 2-(1-Hydroxyethyl)-6-ethylaniline in Milk and

Beef Tissues. Unpublished study prepared by Monsanto Co. 20 p.

00159364 Danhaus, R.; Kunstman, J.; Oppenhuizen, M.; et al. (1986) Operator Exposure from Closed

System Transfer and Application of Lasso EC and Lasso MT Herbicides: Report No.

MSL-5320; Project No. 7124. Unpublished study prepared by Monsanto Agricultural Co. 89

p.

00159365 Danhaus, R.; Kunstman, J.; Oppenhuizen, M.; et al. (1986) Operator Exposure from

Open-pour Transfer and Application of Lasso EC, Lasso MT and Lasso WDG Herbicides:

Report No. MSL-5398; Project No. 7124. Unpublished study prepared by Monsanto

Agricultural Co. 94 p.

00155389 Kier, L. (1985) Overview of Ames/Salmonella Test Results on Alachlor and Metabolites. 

Unpublished study prepared by Monsanto Co. 9 p.

00155391 Kier, L. (1985) Ames/Salmonella Mutagenicity Assays of Synthesized Metabolites (CP101384

and CP97230): Final Report: Study No. 850007 and Project No. ML-850007. Unpublished

study prepared by Monsanto Co. 27 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

240

00155392 Kier, L. (1985) Ames/Salmonella Mutagenicity Assays of Urine from Long-Evans Rats:

Project No. ML-84-157, ML-84-325. Unpublished study prepared by Environmental Health

Lab. 92 p.

00155393 Kier, L. (1985) Ames/Salmonella Mutagenicity Assays of Bile from Long-Evans Rats: Project

No. ML-84-182. Unpublished study prepared by Environmental Health Laboratory. 44 p.

00155732 Adams, S.; Graham, J.; Pijanowski, P. (1985) Reanalysis of Corn Grain for Alachlor Residues

from Two Metabolite Classes by Gas Chromatography/Mass Spectrometry: Project No.: 7124

and Report No.: MSL-4534. Unpublished study prepared by Monsanto Co. 64 p.

00158911 Lauer, R.; Smith, R.; Baszis, S.; et al. (1986) Alachlor in Raw and Finished Drinking Water

Derived from Surface Sources from 24 Community Water Systems Located in Regions of

Extensive Lasso Use: Report No. MSL-5412 and Project No. 7135. Unpublished study

prepared by Monsanto Co. 542 p.

00159793 Graham, J.; Marshall, M.; Arras, D. (1986) Alachlor Residues from Two Metabolite Classes in

Corn Commodities following Preemergent Treatment with Lasso and Lasso Micro-Tech

Herbicides: Report No. MSL-5603: Job/Project No.7124/7118. Unpublished study prepared

by Monsanto Agricultural Co. 284 p.

00159796 Marshall, M. (1986) Alachlor Residues from Two Metabolite Classes in Milo Forage, Milo

Stover and Milo Grain: Report No. MSL-5534. Unpublished study prepared by Monsanto

Agricultural Co. 161 p.

00159936 Hackett, A.; Graham, J.; Arras, D. (1986) Determination of Alachlor Metabolite Residues from

Two Metabolite Classes in Peanut Hay, Vines, Hulls and Nutmeat: Report No. MSL-4636:

Job/Project No. 7124. Unpublished study prepared by Monsanto Agricultural Co. 215 p.

00161728 Auletta, C.; Daly, I. (1983) A Dermal Sensitization Study in Guinea Pigs: Alachlor:

Bio/dynamics Project No. 4030-82; Monsanto Reference No. BD-82-206. Unpublished study

prepared by Bio/dynamics Inc. 20 p.

00162937 Monsanto Co. (1986) Protocol To Determine Residues of Alachlor Metabolites in Processed

Peanut Commodities: Protocol No. 87-24-R-1. Unpublished compilation. 50 p.

00162939 Marshall, M.; Arras, D. (1986) Alachlor Residues from Two Metabolite Classes in Corn and

Dry-milled Processed Corn Fractions: Report No. MSL-5943: Job/Project No. 7124. 

Unpublished study prepared by Monsanto Co. 208 p.

40000901 Howe, R.; Carr, K.; Chott, R. (1986) The Metabolism of Alachlor in Rhesus Monkeys: Part II:

Identification, Characterization, and Quantification of Alachlor and Its Metabolites after
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

241

Intravenous Administration to Monkeys: Project No. 7824. Unpublished study prepared by

Monsanto Agricultural Co. 111 p.

40039901 Adams, S. (1986) Alachlor Metabolite Residues from Two Metabolite Classes in Succulent

Peas, Lima Beans and Snap Beans: Project No. 062435: Report No. MSL-6218. Unpublished

study prepared by Monsanto Agricultural Co. 134 p.

40040101 Lauer, R.; Horner, L. (1986) Determination of Alachlor Residues in Sunflower Seeds, Crude

Oil and Meal with Hulls: Project No. 062435: Report No. MSL-6201. Unpublished study

prepared by Monsanto Agricultural Co. 90 p.

40040301 Adams, S. (1986) Alachlor Metabolite Residues from Two Metabolite Classes in Dry Peas and

Dry Lima, Navy, Pinto, and Red Kidney Beans: Project No. 062435: Report No. MSL-6224. 

Unpublished study prepared by Monsanto Agricultural Co. 161 p.

40040401 Marshall, M.; Arras, D. (1986) Alachlor Residues from Two Metabolite Classes in Peanuts,

Peanut Protein and Peanut Oil Fractions: Project No. 062435: Report No. MSL-6100. 

Unpublished study prepared by Monsanto Agricultural Co. 252 p.

40094602 Johnson, W.; Finley, M. (1980) Handbook of Acute Toxicity of Chemicals to Fish and Aquatic

Invertebrates: Resource Publication 137. US Fish and Wildlife Service, Washington, D.C. 106

p.

40098001 Mayer, F.; Ellersieck, M. (1986) Manual of Acute Toxicity: Interpretation and Data Base 410

Chemicals and 66 Species of Freshwater Animals. US Fish and Wildlife Service; Resource

Publication (160): 579 p.

40189701 Adams, S. (1987) Alachlor Metabolite Residues from Two Metabolite Classes in Dry Peas and

Dry Lima, Navy, Pinto and Red Kidney Beans: Project No. 062435: Appendix H--Dates of

Fortification, Extraction and Final Determination. Unpublished study prepared by Monsanto

Agricultural Co. 100 p.

40240901 Lauer, R.; Horner, L. (1987) Determination of Alachlor Residue in Sunflower Seeds Following

Preemergent Application of Lasso Herbicide: Lab Project ID: MSL-6541. Unpublished study

prepared by Monsanto Agricultural Co. 194 p.

40265901 Smith, R.; Triebe, F.; Baszis, S. (1987) Alachlor, Atrazine, Cyanazine, Metolachlor and

Simazine in Surface Water from 30 Community Water Systems Located in Regions of Lasso

Use: Project No. 062430; Report No. MSL-6787. Unpublished study prepared by Monsanto

Agricultural Co. 505 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

242

40271801 Marshall, M.; Arras, D. (1987) Residues of Alachlor from Two Metabolite Classes in Milo

Forage, Milo Fodder and Milo Grain: Laboratory Project No. MSL-6397. Unpublished

compilation prepared by Monsanto Agricultural Co. 368 p.

40271802 Marshall, M.; Jablonski, J.; Arras, D. (1987) Residues of Alachlor from Two Metabolite

Classes in Milo Grain Fractions: Laboratory Project No. MSL-6645. Unpublished compilation

prepared by Monsanto Agricultural Co. 328 p.

40314601 Lauer, R.; Horner, M. (1987) Determination of Alachlor Residues in Sunflower Fractions

Following Preemergnt (sic) Application of Lasso Herbicide to Sunflower Seeds: Lab. Proj. I.D.

MSL-6799. Unpublished study prepared by Monsanto Agricultural Co. in cooperation with

Texas A&M Univ. 527 p.

40330301 Pijanowski, P.; Adams, S. (1987) Alachlor Metabolite Residues from Two Metabolite Classes

in Cooked and Processed Legume Vegetables: Laboratory Project No. MSL-6750. 

Unpublished study prepared by Monsanto Agricultural Co. 186 p.

40341201 Adams, S.; Pijanoski, P. (1987) Alachlor Metabolite Residues from Two Metabolite Classes in

Dry Peas and Dry Lima, Navy, Pinto and Red Kidney Beans: Lab. Proj. No. MSL-6832. 

Unpublished study prepared by Monsanto Agricultural Co. 330 p.

40393901 Monsanto Agricultural Company (1987) Further Characterization of Carbon-14 Residues in

Tissues and Milk from Lactating Goats Treated with Synthetic Carbon-14-Labeled Plant

Metabolites of Alachlor. Unpublished study. 10 p.

40394001 Monsanto Co. (1987) Further Characterization of Carbon 14 Residues in Tissues and Eggs

from Laying Hens Treated with Synthetic Carbon 14-labeled Plant Metabolites of Alachlor:

R.D. No. 829. Unpublished study. 11 p.

40396301 Monsanto Co. (1987) Alachlor Product Chemistry--Response to Agency Review: R.D. No.

831. Unpublished study. 47 p.

40491101 Graham, J.; Marshall, M.; Arras, D. (1987) Stability of Alachlor Residues in Selected Raw

Agricultural Commodities: Laboratory Project No. MSL-7201: R.D. No. 846. Unpublished

study prepared by Monsanto Agricultural Co. 643 p.

40502101 Adams, S.; Graham, J.; Pijanowski, P.; et al. (1986) Additional Information Requested in the

Agency Review of the Alachlor General Residue Chemistry Data. Unpublished study prepared

by Monsanto Agricultural Co. 95 p.

40511201 Monsanto Agricultural Co. (1988) Additional Information: Requested in the Agency Review of

the Alachlor General Residue Chemistry Data: ... in Milo Forage, Milo Stover, and Milo Grain:

R.D. No. 852. Unpublished study. 34 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

243

40511301 Monsanto Agricultural Co. (1988) Additional Information: Requested in the Agency Review of

the Alachlor General Residue Chemistry Data: R.D. No. 851. Unpublished study. 82 p.

40511901 Monsanto Agricultural Co. (1988) Additional Information Requested in the Agency Review of

the Alachlor: General Residue Chemistry. Unpublished additions to the studies. 106 p.

40529201 Lauer, R.; Horner, L. (1987) Analytical Methodology for Residue Determination of Alachlor in

Sunflower Seeds and Sunflower Fractions Using an Electrochemical Detector: Laboratory

Project ID MSL-7240. Unpublished study prepared by Monsanto Agricultural Company. 93

p.

40558001 Hackett, A.; Holden, L.; Graham, J. (1988) Regulatory Enforcement Method for the

Determination of Alachlor Residues in Raw Agricultural Commodities: Laboratory Project No.

MSL-7601. Unpublished study prepared by Monsanto Agricultural Co. 66 p.

40579402 Schroeder, R. (1988) A Teratogenicity Study in Rabbits with Alachlor: Laboratory Project No.

87-3169: R.D. No. 863. Unpublished study prepared by Bio/dynamics, Inc. 294 p.

40628301 Lauer, R.; Horner, L.; Holden, L. (1988) Stability of Alachlor Residues in Sunflower Seeds

and Sunflower Fractions: Laboratory Project No. MSL-7323: R.D. No. 867. Unpublished

study prepared by Monsanto Agricultural Co. 292 p.

40662601 Arras, D.; Graham, J.; Marshall, M.; et al. (1986) Combined Residues of Alachlor from Two

Classes of Metabolites in Corn Forage, Stover and Grain...and Lasso Micro-Tech Herbicides:

MSL-4626: R.D. No. 606. Unpublished study prepared by Monsanto Agricultural Co. 259 p.

40788201 Marshall, M.; Arras, D. (1988) Alachlor Residues from Two Metabolite Classes in Wet-milled

Processed Corn Fractions: R.D. No. 882. Unpublished study prepared by Monsanto

Agricultural Co. 392 p.

40820601 Hackett, A.; Jablonski, J. (1988) Magnitude of the Residue: Alachlor Residues from Two

Metabolite Classes in Whole Peanuts and Processed Peanut Commodities: Laboratory Project

No. MSL-7847. Unpublished study prepared by Monsanto Agricultural Co. 203 p.

40820701 Marshall, M. (1988) Alachlor Residues from Two Metabolite Classes in Processed (Canned)

Dry Bean Fractions: Laboratory Project No. MSL-8121. Unpublished study prepared by

Monsanto Agricultural Co. 256 p.

40946901 Marshall, M.; Arras, D. (1988) Stability of Alachlor Residues in Selected Raw Agricultural

Commodities Held in Frozen Storage: Lab. Proj. No. MSL-8550. Unpublished study prepared

by Monsanto Agricultural Co. 303 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

244

40947101 Fleschar, E.; Marshall, M. (1988) Alachlor Residues From Two Metabolite Classes in

Processed Soybean Fractions: Lab. Proj. No. MSL-8539. Unpublished study prepared by

Monsanto Agricultural Co. 316 p.

41083801 Marshall, M.; Arras, D. (1988) Alachlor Residues from Two Metabolite Classes in Dry Bean

Raw Agricultural Commodities: Project No. MSL-8098; R.D. No. 888. Unpublished study

prepared by Monsanto Agricultural Co. 272 p.

41400001 Holden, L.; Graham, J. (1990) The National Alachlor Well Water Survey: Project Summary:

Lab Project Number: MSL-9633: R. D. No. 973. Unpublished study prepared by Monsanto

Agricultural Co. 26 p.

41400002 Holden, L.; Graham, J.; Gustafson, D.; et al. (1990) The National Alachlor Well Water Survey.

Part A. Well Selection and Water Sample Collection: Lab Project Number: MSL-9627: R. D.

No. 973. Unpublished study prepared by Monsanto Agricultural Co. 450 p.

41400003 Smith, R.; Schuette, S.; Holden, L. (1990) The National Alachlor Well Water Survey: Part B:

Chemical Analysis: Lab Project Number : MSL-9628: R.D. NO. 973. Unpublished study

prepared by Monsanto Agricultural Co. 305 p.

41400004 Holden, L.; Graham, J.; Gustafson, D. (1990) The National Alachlor Well Water Survey: Part

C: Statistical Analysis: Lab Project Number: MSL-9629: R.D. NO. 973. Unpublished study

prepared by Monsanto Agricultural Co. 346 p.

41949601 Hughes, D. (1991) Multiresidue Protocol Evaluation for Compounds CP-101394, CP-108065,

CP-108064, CP-108267: Final Report Lab Project No: HWI 6103-139: 0624-91-5: MSL11187. Unpublished study prepared by Hazleton Wisconsin, Inc. 190 p.

41856301 Monsanto Agricultural Co. (1991) [Recovery of DEA in Peanut Crops]: Unpublished study. 

152 p.

41862901 Monsanto Agricultural Co. (1991) Alachlor: Response to Alachlor Petition for Soybean Grain

Tolerance of 1.0 ppm, EPA PP# 9F3776: Supplement to: Lab Project Number: 1042. 

Unpublished study. 93 p.

41916001 Arras, D.; Warner, J. (1991) Regulatory Enforcement Method for the Determination of

Alachlor Residues in Corn Forage, Fodder, Silage and Grain: Lab Project Number:

MSL-11154: 39357: 1047. Unpublished study prepared by Monsanto Agricultural Company

and ABC Laboratories, Inc. 79 p.

41916301 Penney, R.; Snyder, H. (1991) Review of Monsanto's Study of Alachlor Residues in Soybean

Protein Fractions: Lab Project Number: 1048. Unpublished study prepared by University of

Arkansas. 90 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

245

41949601 Hughes, D. (1991) Multiresidue Protocol Evaluation for Compounds CP-101394, CP108065,

CP-198064, CP-108267: Final Report: Lab Project No: HWI 6103-139: 0624-091-5: MSL11187. Unpublished study prepared by Hazleton Wisconsin, Inc. 190 p.

42086001 Arras, D.; Warner, J. (1991) Additional Chromatograms Requested by the EPA to Support the

Proposed Alachlor Enforcement Method, RES-009-91 (Addendum to MRID 41916001): Lab

Project Number: R.D. 1066. Unpublished study prepared by Monsanto Agricultural Co. 23 p.

42158601 Warner, J. (1991) Market Basket Probe for the Study of Alachlor Residues in Commercially

Purchased Peanut Butter: Lab Project Number: MSL-11534: HWI 6103-131: RD 1074. 

Unpublished study prepared by Monsanto Ag. Co. in coop with Hazleton Wisconsin, Inc. 

Transmittal of 1 study.

42192501 Adams, S. (1991) Regulatory Enforcement Method for the Determination of Residues of

Alachlor and its Metabolites in Various Raw Agricultural and Food Commodities: Lab Project

Number: MSL-11613. Unpublished study prepared by Monsanto Agricultural Co. 221 p.

42239501 Adams, S.; Yates-Parker, N. (1992) Alachlor: Response to Alachlor Reregistration Review

Task-4, Storage Stability of Alachlor Residues in Corn Oil: Lab Project Number: R.D. 1081.

Unpublished study prepared by Monsanto Agricultural Co. 67 p.

42276701 Arras, D. (1990) Alachlor Residues from Two Metabolite Classes in Commercially Purchased

Peanut Butter: Supplemental Data: Lab Project Number: MSL-10725. Unpublished study

prepared by Monsanto Agriculturla Comp. 32 p.

42286701 Andrews, K.; Schweitzer, M. (1992) PR-88-5 Method Validation for Alachlor Metabolites in

Corn Grain, Peanut Meat and Soybean Grain: Lab Project Number: RD 1084. Unpublished

study prepared by Battelle. 265 p.

42286702 Moye, H.; Anderson, A. (1992) Validation of an Analytical Method for Alachlor and its

Metabolites on Corn Fodder and Forage: Lab Project Number: RD 1084. Unpublished study

prepared by Univ. of Fla., Gainesville. 65 p.

42300701 Warner, J.; Adams, S. (1992) Market Basket Probe for the Study of Alachlor Residues in

Commercially Purchased Soy-Based Infant Formula: Lab Project Number: MSL-11669:

6103-146. Unpublished study prepared by Monsanto Agric. Co. and Hazleton Wiscousin, Inc. 

126 p.

42302001 Adams, S.; Yates-Parker,N. (1992) Alachlor Reregistration Standard: Peanut Processing Study

Chromatograms from MSL-6100, MRID 40040401: Lab Project Number: RD 1087. 

Unpublished study prepared by Monsanto Ag Co. 148 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

246

42308701 Adams, S. (1992) Purity of the Reference Standard for Alachlor Residue Studies Conducted

between April 1985 and December 1988: Lab Project Number: 1093. Unpublished study

prepared by Monsanto Agricultural Co. 47 p.

42309001 Monsanto Agricultural Co. (1992) Response to the EPA Review of Monsanto's Request for a

0.7 ppm Tolerance Request for Soybean Grain, PP# 9F3776: Lab Project Number: R.D. 1088. 

Unpublished study. 22 p.

42313301 Yates-Parker, N. (1992) Response to the February 28, 1992 Review Document for

PP#9F3776: Alachlor Use in/on Soybeans. Unpublished study prepared by Monsanto

Agricultural Co. 25 p.

42348901 Adams, S. (1992) Residues of Alachlor in Soybean Raw Agricultural Commodities Following

Pre-emergence and Pre-plant Incorporated Application of Lasso II Granules: Lab Project

Number: MSL 11865: 91-24-R-3: 39530. Unpublished study prepared by Monsanto Ag. Co.,

Stewart Ag Res. Serv., ABC Labs, Inc. and Hazleton Wisc., Inc. 304 p.

42348902 Adams, S. (1992) Residues of Alachlor in Field Corn Raw Agricultural Commodities

Following Pre-emergence and Pre-plant Incorporated Application of Lasso II Granules: Lab

Project Number: MSL 11866: 91-24-R-3: 39530. Unpublished study prepared by Monsanto

Ag. Co., Stewart Ag Res. Serv., ABC Labs, Inc. and Hazleton Wisc., Inc. 371 p.

42349101 Adams, S. (1992) Residues of Alachlor in Field Corn and Soybean Raw Agricultural

Commodities Following Pre-emergence and Pre-plant Incorporated Application of Lasso II

Granules, MON 29810, and MON 29811: Lab Project Number: MSL 11833: 91-24-R-3:

39530. Unpublished study prepared by Monsanto Ag Co., Stewart Ag Res. Serv., ABC Labs,

Inc. and Hazleton Wisc., Inc. 1416 p.

42395301 Kimmel, E. (1992) Confined Rotational Crop Study of Alachlor Part I (Field Phase): Lab

Project Number: 256W-1: 256-W: 90-24-M17. Unpublished study prepared by PTRL-West,

Inc. 94 p.

42395302 Hackett, A.; Horton, S.; Fujiwara, H.; et al. (1992) Confined Rotational Crop Study of

Alachlor. Part II: Quantitation, Characterization, and Identification of Alachlor-Derived

Residues: Lab Project Number: MSL-11949: 1107. Unpublished study prepared by Monsanto

Co., The Agricultural Group. 182 p.

42468601 Canez, V. (1992) Tier 2 Vegetative Vigor Nontarget Phytotoxicity Study Using Alachlor: Lab

Project Number: BL91-480: 0624-91-9. Unpublished study prepared by Pan-Agricultural

Laboratories Inc. 226 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

247

42468701 Chetram, R. (1992) Tier 2 Seed Germination/Seedling Emergence Nontarget Phytotoxicity

Study Using Alachlor: Lab Project Number: BL91-481: 0624-91-8. Unpublished study

prepared by Pan-Agricultural Laboratories Inc. 281 p

42479901 Gibson, K.; Adams, S. (1992) Analysis of Well Water for Residues of Alachlor Sulfonate

Metabolite: Lab Project Number: MSL-1185: RD 1134. Unpublished study prepared by

Monsanto Ag. Co. 57 p.

42485703 Atkins, R. (1992) Soil Adsorption/Desorption of Carbon-14 Propachlor Oxanilic Acid by the

Batch Equilibrium Method: Lab Project Number: MSL-12228: 653: RD 1133. Unpublished

study prepared by PTRL-East Inc. 107 p.

42485704 Atkins, R. (1992) Soil Adsorption/Desorption of Carbon-14 Propachlor Sulfonic Acid by the

Batch Equilibrium Method: Lab Project Number: MSL-12229: 654: RD 1133. Unpublished

study prepared by PTRL-East Inc. 96 p.

42528001 Schott, M.; Schlicher, M. (1990) Terrestrial Field Dissipation of Alachlor at Two Sites in

California: Lab Project Number: MSL-10395: RD 1138. Unpublished study prepared by

Monsanto, Company. 313 p.

42528002 Schlicher, M.; Schott, M. (1991) Terrestrial Field Dissipation of Alachlor Metabolites in Chico,

California: Lab Project Number: MSL-10844: 1138. Unpublished study prepared by

Monsanto, Company. 251 p.

42528003 Schneider, D. (1991) Storage Stability of Alachlor and Alachlor Metabolites in Soil: Lab

Project Number: MSL-11592: 1138. Unpublished study prepared by Monsanto, Company. 94

p.

42528004 Kludas, R. (1991) PANG Laboratory Quality Assurance and Site Information Terrestrial Field

Disspiation [sic] of Alachlor at Two Sites in California: Lab Project Number: RD 1138:

89-24-R-1: 0624-89-2. Unpublished study prepared by Pan-Agricultural Labs, Inc. and

Chemtec, Inc. 20 p.

42594901 Downs, J.; Marsh, D.; Krautter, G. (1992) The Metabolism of Two (carbon 14)-Labelled

Alachlor Metabolites in Lactating Goats: Part 1: In-life Aspects and Quantification of (carbon

14)-Residues in Milk, Tissues, and Excreta: Lab Project Number: 601: 1409: MSL-12108. 

Unpublished study prepared by PTRL East, Inc. 82 p.

42594902 Downs, J.; Marsh, D.; Krautter, G. (1992) The Metabolism of Two (carbon 14)-Labelled

Alachlor Metabolites in Laying Hens: Part 1: In-life Aspects and Quantification of (carbon

14)-Residues in Eggs, Tissues, and Excreta: Lab Project Number: 602: 1411: MSL-12197. 

Unpublished study prepared by PTRL East, Inc. 81 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

248

42594903 Nadeau, R.; Flory, D.; Schneider, R.; et al. (1992) The Metabolism of Two (carbon

14)-Labeled Alachlor Metabolites in Lactating Goats: Part II: Quantitation Characterization,

and Identification of the Radioactive Residues in Milk and Tissues: Lab Project Number:

MSL-12416: 1145. Unpublished study prepared by Monsanto. 300 p.

42594904 Nadeau, R.; Flory, D.; Schneider, R.; et al. (1992) The Metabolism of Two (carbon

14)-Labeled Alachlor Metabolites in Laying Hens: Part II: Quantitation Characterization, and

Identification of the Radioactive Residues in Eggs and Tissues: Lab Project Number:

MSL-12417: 1145. Unpublished study prepared by Monsanto. 301 p.

42651301 Kier, L.; Stegeman, S. (1990) Ames/Salmonella Mutagenicity Assays of Alachlor,

2',6'-Diethyl-2-Methylthioacetanilide (Alachlor Secondary Sulfide) and 2,6-Diethylaniline

without S9 and with Nasal Turbinate S9s from Rat, Mouse and Monkey: Lab Project Number:

EHL 90128: EHL 90129: EHL 90130. Unpublished study prepared by Monsanto Company. 

112 p.

42651302 Hamilton, C. (1992) Measurement of Unscheduled DNA Sythesis and S-Phase Synthesis in

Male Fischer-344 Rat Hepatocytes following In vivo Treatment with Alachlor: Lab Project

Number: 2877-U01-91: 1156. Unpublished study prepared by SRI International. 93 p.

42651303 Kier, L. (1992) Rat Bone Marrow Micronucleus Assay of Alachlor: Lab Project Number: EHL

91102: 1156. Unpublished study prepared by Monsanto Company. 44 p.

42651304 Wilson, A.; Hall, L. (1988) A Study of the Distribution and Localization of

Alachlor-Methylsulfide in Rats using Whole-body Autoradiography: Lab Project Number: EHL

86101: 1156. Unpublished study prepared by Monsanto Company. 26 p.

42651305 Wilson, A.; Reisch, C. (1985) The Study of Alachlor Metabolism and Elimination in the

Mouse: Part I: Lab Project Number: EHL 840084: ML-84-271: 1156. Unpublished study

prepared by Monsanto Company. 116 p.

42651306 Wilson, A.; Hall, L. (1986) Pharmacokinetic Study of Alachlor Distribution and Elimination in

the Long-Evans Rat: Part I: Absorption, Distribution and Excretion: Lab Project Number:

EHL 84027: ML-84-096: 1156. Unpublished study prepared by Monsanto Company. 61 p.

42651307 Wilson, A.; Hall, L. (1986) A Study of the Metabolism and Excretion of Alachlor in Rats

Chronically Exposed to Alachlor: Part I: Routes and Rates of Elimination: Lab Project

Number: EHL 85040: ML-85-110: 1156. Unpublished study prepared by Monsanto

Company. 61 p.

42651308 Stoltz, M. (1986) A Metabolism Study of Alachlor in the Laboratory Rat following

Intravenous Administration: Lab Project Number: MRI-8129-A(5): 8129-A(5): 1156. 

Unpublished study prepared by Midwest Research Institute. 71 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

249

42651309 McClanahan, R. (1988) Metabolism of Alachlor Methyl Sulfide in Long-Evans Rat: Lab

Project Number: MSL-7585: 7585: 1156. Unpublished study prepared by Monsanto. 44 p.

42651310 Wilson, A.; Hall, L. (1989) Effect of Multiple Oral Dosing on the Metabolism, Distribution and

Elimination of Alachlor in the Long-Evans Rat: Part I: Lab Project Number: EHL 86071:

86071: ML-86-207: 1156. Unpublished study prepared by Monsanto. 36 p.

42651311 Ridley, W.; Warren, J.; Mueller, J. (1986) A Study of the In vitro Liver Slice Metabolism of

Alachlor in the Male Rat, Mouse and Monkey: Lab Project Number: ML-84-195: EHL

840071: 840079: 1156. Unpublished study prepared by Monsanto. 64 p.

42651312 Ridley, W.; Warren, J.; Lewis, M. (1988) A Study of the In vitro Metabolism of Alachlor using

Enzyme Preparations from Selected Rat Tissues: Part I: Preparation of Tissue Homogenates:

Lab Project Number: 86103: ML-86-322: 1156. Unpublished study prepared by Monsanto. 19

p.

42651314 Li, A.; Asbury, K.; Hopkins, W. (1990) In vitro Metabolism of Alachlor, Alachlor Secondary

Methylsulfide (2,6-Diethyl-2-Methylthioacetanilide), and 2,6-Diethylaniline by Rat and Monkey

Nasal Turbinate Tissue: Lab Project Number: 90160: ML-90-428: 1156. Unpublished study

prepared by Monsanto. 26 p.

42651318 Wilson, A.; Reisch, C. (1987) Effects of Alachlor on Tissue Levels on Glutathione in the Rat:

Lab Project Number: 83167: ML-83-320: 1156. Unpublished study prepared by Monsanto. 

47 p.

42701501 Bonnette, K. (1993) Acute Oral Toxicity Study in Rats with MON 5775: Final Report: Lab

Project Number: 3044.303: SB-92-131. Unpublished study prepared by Springborn Labs, Inc. 

44 p.

42741601 Sidhu, R. (1993) Residues of Alachlor in Field Corn Commodities Following Postemergence

and Sequential Applications of Micro-Tech Herbicide: Lab Project Number: MSL-12594:

40496: 0624-92-4. Unpublished study prepared by The Agricultural Group of Monsanto

Company, ABC Laboratories, and Stewart Agricultural Research Services, Inc. 687 p.

42763801 Blasberg, J.; Hicks, S.; Leak, T. (1993) Acute Toxicity of (carbon 14)-Alachlor to Selenastrum

capricornutum Printz: Final Report: Lab Project Number: 40815: AB-93-52: 1171.

Unpublished study prepared by ABC Labs, Inc. 56 p.

42852102 Brewster, D.; Hotz, K. (1991) A Study to the Effect of Alachlor on Cell Proliferation in

Specific Tissues of the Rat and Mouse: Lab Project Number: HL 87112,90059,90114: R.D.

1156: 90114. Unpublished study prepared by Monsanto Co. 95 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

250

42852103 Ribelin, W.; Wilson, A. (1985) Whole-Body Autoradiography Studies on (carbon 14)-Alachlor

in Rats, Mice and Monkeys: Lab Project Number: EHL 840025: R.D. 1156: ML-84-107. 

Unpublished study prepared by Monsanto Co. 42 p.

42852104 Wilson, A.; Hall, L. (1989) A Comparative Study of the Distribution and Localization of

Alachlor, Metolachlor and MON 4601 in Rats Using Whole-Body Autoradiography: Lab

Project Number: EHL 86029: R.D. 1156: ML-86-190. Unpublished study prepared by

Monsanto Co. 46 p.

42852105 Hall, L.; Wilson, A. (1992) A Comparison of the Distribution and Excretion of Radiolabeled

Alachlor in the Sprague-Dawley, Fisher 344 and Long-Evans Rat and Golden Syrian Hamster:

Lab Project Number: EHL 91020: ML-91-96: R.D. 1156. Unpublished study prepared by

Monsanto Co. 43 p.

42852106 Howe, R.; Carr, K.; Chott, R. (1986) The Study of Alachlor Metabolism in Mice. Part II:

Identification, Characterization, and Quantification of Alachlor and its Metabolites after Oral

Administration to CD-1 Mice: Lab Project Number: MSL-5054: R. D. 1156. Unpublished

study prepared by Monsanto Co. 89 p.

42852107 Howe, R.; Nadeau, R.; Chott, R. (1986) Metabolism of Alachlor in Long-Evans Rats. Part II:

Identification, Characterization, and Quantification of Alachlor and its Metabolites after Oral

Administration: Lab Project Number: MSL-5052: R.D. 1156. Unpublished study prepared by

Monsanto Co. 240 p.

42852108 Howe, R.; Chott, R. (1986) Metabolism of Alachlor in the Laboratory Rats Following

Intravenous Administration: Lab Project Number: MSL-5886: R.D. 1156. Unpublished study

prepared by Monsanto Co. 67 p.

42852109 Howe, R.; Chott, R.; Duke, J. (1988) Effect of Multiple Dosing on the Metabolism,

Distribution, and Elimination of Alachlor in the Long-Evans Rats. Part II: Lab Project Number:

MSL-7618: R. D. 1156. Unpublished study prepared by Monsanto Co. 82 p.

42852110 Patanella, J.; Feng, P. (1987) In Vitro Metabolism of Alachlor by Rat Liver, Kidney, Lung,

Nasal, and Stomach Homogenates: Lab Project Number: MSL-6677: R.D. 1156. Unpublished

study prepared by Monsanto Co. 50 p.

42852111 Patanella, J.; Feng, P. (1988) In Vitro Metabolism of Alachlor by Rat and Mouse Liver, Nasal

Enzymes: Lab Project Number: MSL-7168: R.D. 1156: 202400. Unpublished study prepared

by Monsanto Co. 33 p.

42863701 Siglin, J. (1993) A 91-Day Drinking Water Toxicity Study in Rats with MON 5775: Final

Report: Lab Project Number: SB-92-383: 3044.372: R.D. 1182. Unpublished study prepared

by Springborn Labs, Inc. 376 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

251

42929901 Sidhu, R. (1993) Alachlor Residues in Sweet Corn Commodities Following Preemergence and

Pre-Plant Incorporated Applications of Lasso II Herbicide: Lab Project Number: R.D. 1189:

MSL-12795: 40715. Unpublished study prepared by The Agricultural Group, Monsanto Co.;

ABC Labs.; Stewart Agricultural Research Services, Inc. 451 p.

42931101 Yalamanchili, G.; Howe, R. (1986) Metabolism of Alachlor in Rats Chronically Exposed to

Alachlor. Part II: Characterization of Metabolites in the Urine and Feces: Lab Project

Number: MSL-5507. Unpublished study prepared by Monsanto Company, Environmental

Health Lab. 74 p.

42934401 Sidhu, R. (1993) Alachlor Residues in Sweet Corn Commodities Following Preemergence,

Pre-plant Incorporated, and Postemergence Applications of Partner Herbicide: Lab Project

Number: 1193: MSL-12796: 40902. Unpublished study prepared by the Agricultural Group of

Monsanto Co., and ABC Laboratories and Stewart Agricultural Research Services, Inc. 484 p.

42957201 Hotz, K.; Brewster, D.; Wilson, A. (1993) Effect of Dietary Exposure of Alachlor on Serum

Levels of TSH in Male Long-Evans Rats: Lab Project Number: 91005/ML-91-307: 1183.

Unpublished study prepared by Monsanto Co., and Ani Lytics, Inc. 132 p.

42961701 Adams, S. (1993) Residues of Alachlor in Peanut Hulls and Nutmeat Following Applications of

Lasso Micro-Tech or Lasso II Granules: Lab Project Number: MSL-12408: HWI 6103-155:

0624-91-2. Unpublished study prepared by Monsanto Agricultural Co.; Hazleton Wisconsin,

Inc. and American Agricultural Services, Inc. 692 p.

43087001 Grimes, J.; Jaber, M. (1986) Alachlor: A Dietary LC 50 Study with the Mallard: Lab Project

Number: 139-232: WL-86-205: RD 1218. Unpublished study prepared by Wildlife

International Ltd. 31 p.

43087101 Grimes, J.; Jaber, M. (1986) Alachlor: A Dietary LC 50 Study with the Bobwhite: Lab Project

Number: RD 1217: 139-231: WL-86-206. Unpublished study prepared by Wildlife

International Ltd. 32 p.

43140001 Schneider, R. (1994) Radiolabeled Validation of the Alachlor Enforcement Method for the

Determination of Alachlor Metabolites Producing 2,6-Diethylaniline (DEA) and

2-(1-Hydroxyethyl)-6-ethylaniline (HEEA) in Animal Products: Lab Project Number:

MSL-13254: 1227. Unpublished study prepared by The Agricultural Group of Monsanto Co. 

159 p.

43267501 Ireland, B.; Acquavella, J.; Farrell, T. et al. (1994) Evaluation of Ocular Health among

Alachlor Manufacturing Workers. Unpublished study prepared by Monsanto Co. and

University of Iowa. 20 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

252

43369201 Asbury, K.; Wilson, A. (1994) Determination of CP 50144-Derived Radioactivity in Rat: Lab

Project Number: 93043: ML/93/197: 1264. Unpublished study prepared by Monsanto

Environmental Health Laboratory. 29 p.

43442001 Schneider, R.; Sidhu, R. (1994) Alachlor Residues in Rotational Crops Following

Preemergence and Postemergence Sequential Applications of Micro-Tech Herbicide to Field

Corn: Lab Project Numbers: 92-24-R-5: 41254: 92-24-R-5A. Unpublished study prepared by

Monsanto Company. 443 p.

43482301 Asbury, K.; Lau, H.; Hopkins, W.; et al. (1994) In vitro Metabolism of Alachlor

2,6-Diethyl-2-Methylthioacetanilide (Alachlor Secondary Sulfide), Alachlor Sec-Amide, and

2,6-Diethylaniline by Rat and Human Nasal Turbinates and Liver: Lab Project Numbers: EHL

92214: ML-93-14: R.D. 1287. Unpublished study prepared by Monsanto Co. 47 p.

43504101 Kinnet, M.; Lau, H.; Ruecker, F. (1994) Effects of Acute Alachlor Exposure of Hepatotixicity

(sic) and Cell Proliferation in the F344 Rat: Lab Project Number: 92198: ML/92/517. 

Unpublished study prepared by Monsanto Environmental Health Lab. 90 p.

43507401 Hall, L.; Wilson, A. (1993) A Study of the Distribution and Localization of Diethylaniline

(DEA) in Rats and Mice Using Whole-Body Autoradiography: Lab Project Number: R.D.

1230: 89081/ML-89-128: EHL 89081. Unpublished study prepared by Monsanto Co. 27 p.

43507601 Roloff, M.; Thake, D.; Heydens, W. (1994) Oncogenicity Study of Alachlor Administered in

Feed to CD-1 Mice for 18 Months: Lab Project Number: MSL-13847: EHL 91166:

ML-92-001. Unpublished study prepared by Monsanto Environmental Health Lab and

Experimental Pathology Labs, Inc. 1636 p.

43590001 Branch, D.; Thake, D. (1995) Gastric Tumor Promotion Study of Alachlor in Long-Evans

Rats: Lab Project Number: ML-93-137: EHL 93049: RD 1295. Unpublished study prepared

by Monsanto Co. 463 p.

43590002 Curtiss, S.; Cabonce, M.; Oakley, L.; et al. (1995) Study of the Effects of Alachlor on Cellular

Stress Response Genes in Rat Nasal Turbinate Tissue: Lab Project Number: ML-94-160: EHL

94081: 1295. Unpublished study prepared by Monsanto Co. 61 p.

43641602 Asbury, K.; Lau, H.; Wilson, A. (1995) A Study of the Effect of Alachlor and Selected

Metabolites on Cytotoxicity Markers in Nasal Tissue of the Long-Evans Rat: Lab Project

Number: EHL 94070: ML-94-169: MSL 14187. Unpublished study prepared by Monsanto

Co. 37 p.

43641603 Vandenberghe, Y.; Kervyn, S. (1995) Effect of Alachlor on Glutathione Levels of Cultured

Adult Rat Hepatocytes: Lab Project Number: XX-95-043. Unpublished study prepared by

Searle European Development Centre. 40 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

253

43641604 Lau, H.; Asbury, K.; McClanahan, R. (1995) Characterization of Covalent Adducts Formed

with Nasal Tissue Protein Following Dietary Administration of (Carbon-14) Alachlor to

Female Long-Evans Rats: Lab Project Number: EHL 94064: ML-94-161. Unpublished study

prepared by Monsanto Co. 72 p.

43706001 Hall, L. (1991) A Study of the Distribution and Localization of Dimethylaniline in Rats and

Mice Using Whole-Body Autoradiography: Lab Project Number: MSL-11227: ML-89-129:

EHL-89082. Unpublished study prepared by Monsanto Environmental Health Lab. 47 p.

43729501 Couch, R.; Hard, G.; Iatropoulos, M. et al. (1995) Effects of Butachlor on the Cell

Proliferation and Mucosal Thickness in the Gastric Tissue of Female Rhesus Monkeys: Lab

Project Number: MSL-14039: WS-93-164: WS-93-165. Unpublished study prepared by

American Health Foundation and White Sands Research Center. 308 p.

43729502 Branch, D.; Thake, D. (1994) Gastric Tumor Initiation/Promotion Study of Butachlor in

Sprague-Dawley Rats: Lab Project Number: ML-92-365: 92142: 1266. Unpublished study

prepared by Monsanto Co. 741 p.

43729503 Reisch, C.; Thake, C.; Wilson, A. (1994) A study of the Effect of Butachlor on Cell

Proliferation in Selected Tissues of the Mouse: Lab Project Number: EHL-93064: ML-93-153:

1266. Unpublished study prepared by American Health Foundation and Monsanto Co. 97 p.

43750801 Thake, D.; Hotz, K.; Reisch, C. et al. (1995) A Study of the Mechanism of Butachlor Induced

Carcinogenicity in Female Sprague-Dawley Rats: Lab Project Number: EHL-92049:

ML-92-146: 1266. Unpublished study prepared by Monsanto, American Health Foundation,

Daiyo-Kai Institute of Medical Science, and others. 1308 p.

43774701 Schneider, R. (1995) Terrestrial Field Dissipation of Alachlor and its Metabolites at Hickman,

California: Lab Project Number: MSL-13960: SARS-93-CA-65: 41125. Unpublished study

prepared by Stewart Agricultural Research Services, Inc. and ABC Labs, Inc. 406 p.

43774702 Phillips, M.; Hall, B. (1995) The Aerobic/Anaerobic Degradation of Radiolabelled Alachlor in

River/Ditch/Pond Waters and Their Associated Sediments: Lab Project Number: IRI 383873:

MSL 14156: 1321. Unpublished study prepared by Inveresk Research International. 104 p.

43774703 Bowman, J.; Hurshman, B. (1994) Acute Toxicity of MON 5775 to Daphnia magna: Final

Report: Lab Project Number: 41728: AB-94-155: R.D. 1321. Unpublished study prepared by

ABC Labs, Inc. 26 p.

43774704 Bowman, J.; Downing, J.; Hurshman, B. (1995) Acute Toxicity of MON 5775 to Rainbow

Trout (Oncorhynchus mykiss): Amended Final Report: Lab Project Number: 41729:

AB-94-156: 1321. Unpublished study prepared by ABC Labs, Inc. 26 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

254

43774705 Bowman, P.; Hurshman, B. (1994) Acute Toxicity of MON 5760 to Dahnia magna: Final

Report: Lab Project Number: 41730: AB-94-153: 1321. Unpublished study prepared by ABC

Labs, Inc. 26 p.

43774706 Bowman, J.; Hurshman, B. (1995) Acute Toxicity of MON 5760 to Rainbow Trout

(Oncorhynchus mykiss): Final Report: Lab Project Number: 41731: AB-94-154: 1321. 

Unpublished study prepared by ABC Labs, Inc. 27 p.

43774707 Forbis, A. (1995) Chronic Toxicity of Alachlor to Daphnia magna Under Flow-Through Test

Conditions: Final Report: Lab Project Number: 41517: AB-94-061: 1321. Unpublished study

prepared by ABC Labs, Inc. 39 p.

43862601 Rhodes, J.; Muckerman, M. (1995) Early Life-Stage Toxicity of Alachlor to the Rainbow

Trout (Oncorhynchus mykiss) Under Flow-Through Conditions: Lab Project Number: 42187:

AB-94-280: R.D. 1331. Unpublished study prepared by ABC Labs, Inc. 339 p.

43878501 Acquavella, J.; Riordan, S.; Anne, M.; et al. (1995) An Update of Mortality and Cancer

Incidence among Alachlor Manufacturing Workers: Epidemiology Report #9501. Unpublished

study prepared by Monsanto Co. and The University of Iowa. 33 p.

43889401 Hotz, K. (1995) Effect of MON 5775 on Cell Proliferation in the Nasal Tissue of Male F-344

Rats: Lab Project Number: ML-95-070: 95034: R.D. 1335. Unpublished study prepared by

Monsanto Co. 19 p.

43889402 Iatropoulos, M.; Wang, C. (1995) Evaluation of Cell Proliferation and Measurement of

Mucosal Thickness in Gastric Fundi of Rats from Study SB-92-383: Lab Project Number:

AH-95-071: R.D. 1335: SB-92-383. Unpublished study prepared by American Health

Foundation. 20 p.

43889403 Stegeman, S.; Kier, L.; Garret, S.; et al. (1995) Mouse Bone Marrow Micronucleus Assay of

MON 5775: Lab Project Number: ML-95-069: EHL 95030: RD 1335. Unpublished study

prepared by Ceregen, Unit of Monsanto Co. 54 p.

43889404 Kraus, L.; Hopkins, W.; Kinnett, M.; et al. (1995) Elimination, Absorption, Tissue

Distribution, and Metabolism of Alachlor Ethane Sulfonate (MON 5775) in Long-Evans Rats

Following Oral Administration: Lab Project Number: ML-95-066: EHL 95031: MSL 14489. 

Unpublished study prepared by Ceregen, Unit of Monsanto Co. 52 p.

43908101 Holson, J. (1995) A Developmental Toxicity Study of MON 5775 in Rats: Lab Project

Number: WIL-50237: WI-95-068: R.D.1335. Unpublished study prepared by WIL Research

Labs, Inc. 292 p.
BIBLIOGRAPHY

MRID CITATION

______________________________________________________

255

44032103 Stegeman, S.; Kier, L.; Albin, L.; et al. (1995) Mouse Bone Marrow Micronucleus Assay of

Alachlor: Lab Project Number: ML-95-231: EHL 95082: RD 1348. Unpublished study

prepared by Monsanto Co., Ceregen Unit. 58 p.

44105503 Kirby-Smith, W.; Eisenreich, S.; Howe, J.; et al. (1993) The Effects in Estuaries of Pesticide

Runoff from Adjacent Farm Lands (Alachlor, Terbufos, Permethrin): Lab Project Number:

CF813415: 1357: R.D. 1357. Unpublished study prepared by Duke University Marine Lab.;

University of Minnesota; and University of North Carolina. 220 p.

44405301 Blumhorst, M. (1997) Soil Adsorption/Desorption of (carbon 14) Alachlor Sulfonic Acid

Metabolite (ESA) by the Batch Equilibrium Method: Lab Project Number: 97-24-M-1:

115S12: MSL-14976. Unpublished study prepared by EPL Bio-Analytical Services, Inc. 106

p.

44492301 Most, J. (1995) Alachlor (Pure) Physico-Chemical Properties: Lab Project Number:

MSL-14400: MTO 41A/942653: PC27-94-6-V-O. Unpublished study prepared by Huntingdon

Research Centre, Ltd. 67 p. {OPPTS 830.7050}

44492302 Monsanto Co. (1998) Monsanto Response to the Draft Health Effects Division Science

Chapter for the Alachlor RED Dated 4 November 1997: Lab Project Number: R.D. NO. 1400. 

Unpublished study. 39 p.

44524301 Graves, W.C.,Swigert, J.P., and Krueger, H.O., (1998) Alachlor: A 96-Hour Flow-Through

Acute Toxicity Test with the Sheepshead Minnow (Cyprinodon variegatus), Project/Study

number 139A-195/WL-96-189, an unpublished report of a study conducted by Wildlife

International, Inc. for Monsanto Life Sciences Company. Guideline Series 72-3

44524302 Graves, W.C.,Swigert, J.P., and Krueger, H.O., (1998) Alachlor: A 96-Hour Flow-Through

Acute Toxicity Test with the Saltwater Mysid (Mysidopsis bahiz), Project/Study number

139A-196/WL-96-190, an unpublished report of a study conducted by Wildlife International,

Inc. for Monsanto Life Sciences Company. Guideline Series 72-3

44524303 Graves, W.C.,Swigert, J.P., and Krueger, H.O., (1998) Alachlor: A 96-Hour Flow-Through

Acute Toxicity Test with the Eastern Oyster (Crassostrea virginica), Project/Study number

139A-197/WL-96-191, an unpublished report of a study conducted by Wildlife International,

Inc. for Monsanto Life Sciences Company. Guideline Series 72-3

44592401 Hackett, A. (1998) Surface Drinking Water Monitoring Program for Acetochlor and Other

Corn Herbicides: Lab Project Number: 94-27-R-3: 94-310: MSL-15395. Unpublished study

prepared by Monsanto Company and Stone Environmental, Inc. 233 p
256

References Not Identified By an MRID Number

Coupe, R.H., Goolsby, D.A., Iverson, J.L., Zaugg, S.D., and Markovchick, D.J., 1995,

Pesticide, nutrient, streamflow and physical property data for the Mississippi River and major tributaries, April

1991-September 1992: U.S. Geological Survey Open-File Report 93-657, 116 p

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature review and evaluation of the EPA food-chain

(Kenaga) nomogram, an instrument for estimating pesticide residues on plants. Environ. Tox. Chem. 13:1383-

1391.

Goolsby D.A. and E.M. Thurman. 1991. Herbicides in rivers and streams of the upper Midwestern United

States. To be published in: Proc. 46th Ann. Meeting Upper Mississippi River Conservation Committee.

Goolsby, D.A., R.C. Coup, and D.J. Markovchick. 1991. Distribution of selected herbicides and nitrate in the

Mississippi River and its major tributaries., April through June, 1991. U. S. Geological Survey Water

Resources Investigations Report p91-4163.

Goolsby, D.A., and Battaglin, W.A., 1993, Occurrence, distribution, and transport of agricultural chemicals in

surface waters of the Midwestern United States, in Goolsby, D.A., Boyer, L.L., and Mallard, G.E., eds.,

Selected papers on agricultural chemicals in water resources of the Midcontinental United States: U.S.

Geological Survey Open-File Report 93-418, p. 1-25

Goolsby, D.A., E.M. Thurman, D.W. Kolpin, and W.A. Battaglin. 1995. Occurrences of herbicides and

metabolites in surface water, ground water, and rainwater in the Midwestern United States. P. 583-591.

Proceedings 1995 Annual Conference. June 18-22, 1995. Anaheim, CA. American Water Works Association.

Goolsby, D.A., Battaglin, W.A., Fallon, J.D., Aga, D.S., Kolpin, D.W., and Thurman, E.M., 1996, Persistence

of herbicides in selected reservoirs in the Midwestern United States--Some preliminary results: Iowa

Groundwater Quarterly, v. 7, no. 2, p. 11-16 (reprinted from U.S. Geological Survey Open-File Report 93-418)

Hoerger, F., and E.E. Kenaga. 1972. Pesticide residues on plants: Correlation of representative data as a basis

for estimation of their magnitude in the environment. In F. Coulston and F. Korte, eds., Environmental Quality

and Safety: Chemistry, Toxicology, and Technology, Georg Thieme Publ, Stuttgart, West Germany, pp. 9-28.

Holden, L.R. and J. A. Graham, 1992. Results of the National Alachlor Well Water Survey. Environ. Sci.

Technol. 26:935-943

ICF Kaiser, Phase II Report. 1992 Review of the Monsanto Company National Alachlor Well Water Survey

Keck, P. 1991. 1991 Missouri River Monitoring Study. Missouri River Public Water Supplies Association. 

Kellog, R.L., M.S. Maizel, and D.W. Goss. 1992. Agricultural Chemical Use and Ground Water Quality:

Where Are the Potential Problem Areas? USDA-SCS Natl. Ctr. for Res. Innov.

Kolpin, D.W. and D.A. Goolsby. 1995. A regional monitoring network to investigate the occurrence of

agricultural chemicals in near-surface aquifers of the midcontinental U.S.A. Groundwater Quality: Remediation

and Protection. 225:13-20
257

Kolpin, D.W., D.A. Goolsby, and E.M. Thurman. 1995. Pesticides in Near-Surface Aquifers: An assessment

using highly sensitive analytical methods and tritium. J. Environ. Qual. 24:1125-1132.

Kolpin, D.W., E.M. Thurman, and D.A. Goolsby. 1996. Occurrence of selected pesticides and their metabolites

in near-surface aquifers of the Midwestern United States.

Mass, R. P., D. J. Hucken, S. C. Patch, B. T. Peek and D. L. Van Engelen, 1995. Pesticides in Eastern North

Carolina Rural Supply Wells: Land Use factors and Persistence. J. Environ. Qual., 24:426-431

Moyer L. and J. Cross. 1990. Pesticide monitoring: Illinois EPA's summary of results, 1985-1989. Illinois EPA.

Potter, T.L., and T.L.Carpenter. 1995. Occurrence of Alachlor Environmental Degradation Products in

Groundwater. Environ. Sci. Technol. 29:1557-1563.

Simons, A. P. and R. E. Fisher, 1997. Time-Related Analysis of Alachlor Concentrations in Florida Wells. Bull.

Environ. Contam. Toxicol., 58:934-938

Squillace P. and R. Engberg. 1988. Surface Water Quality of the Cedar River Basin, Iowa-Minnesota, with

emphasis on the occurrence and transport of herbicides, May 1984 through November, 1985. U.S. Geological

Survey.

Wade, H., C. Bailey, J. Padmore, K. Rudo, B. Williams and A. York, 1997. The interagency study of the impact

of pesticide use on ground water in North Carolina. North Carolina Dept. of Ag. 2109 Blue Ridge Rd.,

Raleigh, NC. 112p

USEPA, 1990. National Pesticide Survey. EPA 734-12-92-001

USEPA, 1992. The Pesticides in Groundwater Database. EPA 570-9-90-015, (Available from: National

Technical Information Service, Springfield, VA: PB91 - 125765INZ).
258

d.Combined Generic and Product Specific Data Call-In
259

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF 

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

GENERIC AND PRODUCT SPECIFIC

DATA CALL-IN NOTICE

CERTIFIED MAIL

Dear Sir or Madam:

This Notice requires you and other registrants of pesticide products containing the active

ingredient identified in Attachment A of this Notice, the Data Call-In Chemical Status Sheet, to

submit certain data as noted herein to the U.S. Environmental Protection Agency (EPA, the

Agency). These data are necessary to maintain the continued registration of your product(s)

containing this active ingredient. Within 90 days after you receive this Notice you must respond as

set forth in Section III below. Your response must state:

1. How you will comply with the requirements set forth in this Notice and its Attachments

1 through 6; or

2. Why you believe you are exempt from the requirements listed in this Notice and in

Attachment 3 (for both generic and product specific data), the Requirements Status and

Reqistrant's Response Form, (see section III-B); or

3. Why you believe EPA should not require your submission of data in the manner

specified by this Notice (see section III-D).

If you do not respond to this Notice, or if you do not satisfy EPA that you will comply with its

requirements or should be exempt or excused from doing so, then the registration of your

product(s) subject to this Notice will be subject to suspension. We have provided a list of all of

your products subject to this Notice in Attachment 2. All products are listed on both the generic

and product specific Data Call-In Response Forms. Also included is a list of all registrants who

were sent this Notice (Attachment 5).

The authority for this Notice is section 3(c)(2)(B) of the Federal Insecticide, Fungicide and

Rodenticide Act as amended (FIFRA), 7 U.S.C. section 136a(c)(2)(B). Collection of this 
260

information is authorized under the Paperwork Reduction Act by OMB Approval No. 2070-0107

and 2070-0057 (expiration date 3-31-99).

This Notice is divided into six sections and six Attachments. The Notice itself contains

information and instructions applicable to all Data Call-In Notices. The Attachments contain

specific chemical information and instructions. The six sections of the Notice are:

Section I - Why You are Receiving this Notice

Section II - Data Required by this Notice

Section III - Compliance with Requirements of this Notice

Section IV - Consequences of Failure to Comply with this Notice

Section V - Registrants' Obligation to Report Possible Unreasonable Adverse Effects

Section VI - Inquiries and Responses to this Notice

The Attachments to this Notice are:

1 - Data Call-In Chemical Status Sheet

2 - Generic Data Call-In and Product Specific Data Call-In Response Forms(Insert A) with

Instructions

3 - Generic Data Call-In and Product Specific Data Call-In Requirements Status and

Registrant's Response Forms (Insert B) with Instructions

4 - EPA Batching of End-Use Products for Meeting Acute Toxicology Data Requirements

for Reregistration

5 - List of Registrants Receiving This Notice

SECTION I. WHY YOU ARE RECEIVING THIS NOTICE

The Agency has reviewed existing data for this active ingredient(s) and reevaluated the data

needed to support continued registration of the subject active ingredient(s). This reevaluation

identified additional data necessary to assess the health and safety of the continued use of

products containing this active ingredient(s). You have been sent this Notice because you have

product(s) containing the subject active ingredient(s).

SECTION II. DATA REQUIRED BY THIS NOTICE

II-A. DATA REQUIRED

The data required by this Notice are specified in the Requirements Status and

Registrant's Response Forms (Insert B) (for both generic and product specific data

requirements). Depending on the results of the studies required in this Notice, additional

studies/testing may be required.

II-B. SCHEDULE FOR SUBMISSION OF DATA
261

You are required to submit the data or otherwise satisfy the data requirements specified

in the Requirements Status and Registrant's Response Forms (Insert B) within the time frames

provided.

II-C. TESTING PROTOCOL

All studies required under this Notice must be conducted in accordance with test

standards outlined in the Pesticide Assessment Guidelines for those studies for which guidelines

have been established.

These EPA Guidelines are available from the National Technical Information Service

(NTIS), Attn: Order Desk, 5285 Port Royal Road, Springfield, VA 22161 (Telephone number:

703-605-6000).

Protocols approved by the Organization for Economic Cooperation and Development

(OECD) are also acceptable if the OECD recommended test standards conform to those

specified in the Pesticide Data Requirements regulation (40 CFR § 158.70). When using the

OECD protocols, they should be modified as appropriate so that the data generated by the study

will satisfy the requirements of 40 CFR § 158. Normally, the Agency will not extend deadlines

for complying with data requirements when the studies were not conducted in accordance with

acceptable standards. The OECD protocols are available from OECD, 2001 L Street, N.W.,

Washington, D.C. 20036 (Telephone number 202-785-6323; Fax telephone number 202-785-

0350).

All new studies and proposed protocols submitted in response to this Data Call-In

Notice must be in accordance with Good Laboratory Practices [40 CFR Part 160].

II-D. REGISTRANTS RECEIVING PREVIOUS SECTION 3(c)(2)(B) NOTICES ISSUED

BY THE AGENCY

Unless otherwise noted herein, this Data Call-In does not in any way supersede or

change the requirements of any previous Data Call-In(s), or any other agreements entered into

with the Agency pertaining to such prior Notice. Registrants must comply with the requirements

of all Notices to avoid issuance of a Notice of Intent to Suspend their affected products.

SECTION III. COMPLIANCE WITH REQUIREMENTS OF THIS NOTICE

You must use the correct forms and instructions when completing your response to this Notice. 

The type of Data Call-In you must comply with (Generic or Product Specific) is specified in item

number 3 on the four Data Call-In forms (Attachments 2 and 3).

III-A. SCHEDULE FOR RESPONDING TO THE AGENCY

The appropriate responses initially required by this Notice for generic and product

specific data must be submitted to the Agency within 90 days after your receipt of this Notice.
262

Failure to adequately respond to this Notice within 90 days of your receipt will be a basis for

issuing a Notice of Intent to Suspend (NOIS) affecting your products. This and other bases for

issuance of NOIS due to failure to comply with this Notice are presented in Section IV-A and

IV-B.

III-B. OPTIONS FOR RESPONDING TO THE AGENCY

1. Generic Data Requirements

The options for responding to this Notice for generic data requirements are: (a)

voluntary cancellation, (b) delete use(s), (c) claim generic data exemption, (d) agree to satisfy

the generic data requirements imposed by this Notice or (e) request a data waiver(s).

A discussion of how to respond if you choose the Voluntary Cancellation option, the

Delete Use(s) option or the Generic Data Exemption option is presented below. A discussion

of the various options available for satisfying the generic data requirements of this Notice is

contained in Section III-C. A discussion of options relating to requests for data waivers is

contained in Section III-D.

Two forms apply to generic data requirements, one or both of which must be used in

responding to the Agency, depending upon your response. These two forms are the

Data-Call-In Response Form(Insert A), and the Requirements Status and Registrant's Response

Form((Insert B). 

The Data Call-In Response Forms(Insert A) must be submitted as part of every response to this

Notice. The Requirements Status and Registrant's Response Forms(Insert B) also must be

submitted if you do not qualify for a Generic Data Exemption or are not requesting voluntary

cancellation of your registration(s). Please note that the company's authorized representative is

required to sign the first page of both Data Call-In Response Forms(Insert A) and the

Requirements Status and Registrant's Response Forms(Insert B) and initial any subsequent pages.

The forms contain separate detailed instructions on the response options. Do not alter the printed

material. If you have questions or need assistance in preparing your response, call or write the

contact person(s) identified in Attachment 1.

a. Voluntary Cancellation - 

You may avoid the requirements of this Notice by requesting voluntary cancellation of your

product(s) containing the active ingredient that is the subject of this Notice. If you wish to

voluntarily cancel your product, you must submit completed Generic and Product Specific Data

Call-In Response Forms(Insert A), indicating your election of this option. Voluntary cancellation

is item number 5 on both Data Call-In Response Form(s). If you choose this option, these are the

only forms that you are required to complete.
263

If you chose to voluntarily cancel your product, further sale and distribution of your product

after the effective date of cancellation must be in accordance with the Existing Stocks provisions

of this Notice, which are contained in Section IV-C.

b. Use Deletion - 

You may avoid the requirements of this Notice by eliminating the uses of your product to which

the requirements apply. If you wish to amend your registration to delete uses, you must submit

the Requirements Status and Registrant's Response Form (Insert B), a completed application for

amendment, a copy of your proposed amended labeling, and all other information required for

processing the application. Use deletion is option number 7 under item 9 in the instructions for

the Requirements Status and Registrant's Response Forms (Insert B). You must also complete a

Data Call-In Response Form(Insert A) by signing the certification, item number 8. Application

forms for amending registrations may be obtained from the Registration Support Branch,

Registration Division, Office of Pesticide Programs, EPA, by calling (703) 308-8358.

If you choose to delete the use(s) subject to this Notice or uses subject to specific data

requirements, further sale, distribution, or use of your product after one year from the due date of

your 90 day response, is allowed only if the product bears an amended label.

c. Generic Data Exemption - 

Under section 3(c)(2)(D) of FIFRA, an applicant for registration of a product is exempt from

the requirement to submit or cite generic data concerning an active ingredient if the active

ingredient in the product is derived exclusively from purchased, registered pesticide products

containing the active ingredient. EPA has concluded, as an exercise of its discretion, that it

normally will not suspend the registration of a product which would qualify and continue to

qualify for the generic data exemption in section 3(c)(2)(D) of FIFRA. To qualify, all of the

following requirements must be met:

(i). The active ingredient in your registered product must be present solely because of

incorporation of another registered product which contains the subject active ingredient and is

purchased from a source not connected with you;

(ii). Every registrant who is the ultimate source of the active ingredient in your product subject

to this DCI must be in compliance with the requirements of this Notice and must remain in

compliance; and

(iii). You must have provided to EPA an accurate and current "Confidential Statement of

Formula" for each of your products to which this Notice applies.

To apply for the Generic Data Exemption you must submit a completed Data Call-In Response

Form(Insert A), Attachment 2 and all supporting documentation. The Generic Data Exemption is

item number 6a on the Data Call-In Response Form(Insert A). If you claim a generic data

exemption you are not required to complete the Requirements Status and Registrant's Response
264

Form (Insert A). Generic Data Exemption cannot be selected as an option for responding to

product specific data requirements.

If you are granted a Generic Data Exemption, you rely on the efforts of other persons to

provide the Agency with the required data. If the registrant(s) who have committed to generate

and submit the required data fail to take appropriate steps to meet requirements or are no longer

in compliance with this Data Call-In Notice, the Agency will consider that both they and you are

not compliance and will normally initiate proceedings to suspend the registrations of both your

and their product(s), unless you commit to submit and do submit the required data within the

specified time. In such cases the Agency generally will not grant a time extension for submitting

the data.

d. Satisfying the Generic Data Requirements of this Notice

There are various options available to satisfy the generic data requirements of this Notice. These

options are discussed in Section III-C.1. of this Notice and comprise options 1 through 6 of item

9 in the instructions for the Requirements Status and Registrant's Response Form(Insert B) and

item 6b on the Data Call-In Response Form (Insert A). If you choose item 6b (agree to satisfy the

generic data requirements), you must submit the Data Call-In Response Form(Insert A) and the

Requirements Status and Registrant's Response Form(Insert B) as well as any other

information/data pertaining to the option chosen to address the data requirement. Your response

must be on the forms marked "GENERIC" in item number 3.

e. Request for Generic Data Waivers.

Waivers for generic data are discussed in Section III-D.1. of this Notice and are covered by

options 8 and 9 of item 9 in the instructions for the Requirements Status and Registrant's

Response Form(Insert B). If you choose one of these options, you must submit both forms as well

as any other information/data pertaining to the option chosen to address the data requirement.

2. Product Specific Data Requirements

The options for responding to this Notice for product specific data are: (a) voluntary

cancellation, (b) agree to satisfy the product specific data requirements imposed by this Notice or

(c) request a data waiver(s).

A discussion of how to respond if you choose the Voluntary Cancellation option is presented

below. A discussion of the various options available for satisfying the product specific data

requirements of this Notice is contained in Section III-C.2. A discussion of options relating to

requests for data waivers is contained in Section III-D.2.

Two forms apply to the product specific data requirements one or both of which must be used

in responding to the Agency, depending upon your response. These forms are the Data-Call-In

Response Form(Insert A), and the Requirements Status and Registrant's Response Form(Insert

B), for product specific data. The Data Call-In Response Form (Insert A) must be submitted as
265

part of every response to this Notice. In addition, one copy of the Requirements Status and

Registrant's Response Form(Insert B) also must be submitted for each product listed on the Data

Call-In Response Form(Insert A) unless the voluntary cancellation option is selected. Please note

that the company's authorized representative is required to sign the first page of the Data Call-In

Response Form(Insert A) and Requirements Status and Registrant's Response Form (Insert B) (if

this form is required) and initial any subsequent pages. The forms contain separate detailed

instructions on the response options. Do not alter the printed material. If you have questions or

need assistance in preparing your response, call or write the contact person(s) identified in

Attachment 1.

a. Voluntary Cancellation

You may avoid the requirements of this Notice by requesting voluntary cancellation of your

product(s) containing the active ingredient that is the subject of this Notice. If you wish to

voluntarily cancel your product, you must submit a completed Data Call-In Response Form(Insert

A), indicating your election of this option. Voluntary cancellation is item number 5 on both the

Generic and Product Specific Data Call-In Response Forms(Insert B). If you choose this option,

you must complete both Data Call-In response forms. These are the only forms that you are

required to complete. 

If you choose to voluntarily cancel your product, further sale and distribution of your product

after the effective date of cancellation must be in accordance with the Existing Stocks provisions

of this Notice which are contained in Section IV-C.

b. Satisfying the Product Specific Data Requirements of this Notice. 

There are various options available to satisfy the product specific data requirements of this

Notice. These options are discussed in Section III-C. of this Notice and comprise options 1

through 6 of item 9 in the instructions for the product specific Requirements Status and

Registrant’s Response Form(Insert B) and item numbers 7a and 7b (agree to satisfy the product

specific data requirements for an MUP or EUP as applicable) on the product specific Data Call-In

Response Form(Insert A). Note that the options available for addressing product specific data

requirements differ slightly from those options for fulfilling generic data requirements. Deletion of

a use(s) and the low volume/minor use option are not valid options for fulfilling product specific

data requirements. It is important to ensure that you are using the correct forms and instructions

when completing your response to the Reregistration Eligibility Decision document.

c. Request for Product Specific Data Waivers.

Waivers for product specific data are discussed in Section III-D.2. of this Notice and are

covered by option 7 of item 9 in the instructions for the Requirements Status and Registrant's

Response Form(Insert B). If you choose this option, you must submit the Data Call-In Response

Form(Insert A) and the Requirements Status and Registrant's Response Form(Insert B) as well as

any other information/data pertaining to the option chosen to address the data requirement. Your

response must be on the forms marked "PRODUCT SPECIFIC" in item number 3. 
266

III-C SATISFYING THE DATA REQUIREMENTS OF THIS NOTICE

1. Generic Data

If you acknowledge on the Generic Data Call-In Response Form(Insert A) that you agree to

satisfy the generic data requirements (i.e. you select item number 6b), then you must select one of

the six options on the Generic Requirements Status and Registrant's Response Form(Insert B)

related to data production for each data requirement. Your option selection should be entered

under item number 9, "Registrant Response." The six options related to data production are the

first six options discussed under item 9 in the instructions for completing the Requirements Status

and Registrant's Response Form. These six options are listed immediately below with information

in parentheses to guide you to additional instructions provided in this Section. The options are:

(1) I will generate and submit data within the specified timeframe (Developing Data)

(2) I have entered into an agreement with one or more registrants to develop data jointly

(Cost Sharing) 

(3) I have made offers to cost-share (Offers to Cost Share)

(4) I am submitting an existing study that has not been submitted previously to the Agency

by anyone (Submitting an Existing Study) 

(5) I am submitting or citing data to upgrade a study classified by EPA as partially

acceptable and upgradeable (Upgrading a Study)

(6) I am citing an existing study that EPA has classified as acceptable or an existing study

that has been submitted but not reviewed by the Agency (Citing an Existing Study)

Option 1. Developing Data

If you choose to develop the required data it must be in conformance with Agency guidelines

and with other Agency requirements as referenced herein and in the attachments. All data

generated and submitted must comply with the Good Laboratory Practice (GLP) rule (40 CFR

Part 160), be conducted according to the Pesticide Assessment Guidelines (PAG) and be in

conformance with the requirements of PR Notice 86-5. In addition, certain studies require Agency

approval of test protocols in advance of study initiation. Those studies for which a protocol must

be submitted have been identified in the Requirements Status and Registrant's Response

Form(Insert B) and/or footnotes to the form. If you wish to use a protocol which differs from the

options discussed in Section II-C of this Notice, you must submit a detailed description of the

proposed protocol and your reason for wishing to use it. The Agency may choose to reject a

protocol not specified in Section II-C. If the Agency rejects your protocol you will be notified in

writing, however, you should be aware that rejection of a proposed protocol will not be a basis

for extending the deadline for submission of data.

A progress report must be submitted for each study within 90 days from the date you are

required to commit to generate or undertake some other means to address that study requirement,

such as making an offer to cost share or agreeing to share in the cost of developing that study. 

This 90-day progress report must include the date the study was or will be initiated and, for
267

studies to be started within 12 months of commitment, the name and address of the

laboratory(ies) or individuals who are or will be conducting the study.

In addition, if the time frame for submission of a final report is more than 1 year, interim reports

must be submitted at 12 month intervals from the date you are required to commit to generate or

otherwise address the requirement for the study. In addition to the other information specified in

the preceding paragraph, at a minimum, a brief description of current activity on and the status of

the study must be included as well as a full description of any problems encountered since the last

progress report.

The time frames in the Requirements Status and Registrant's Response Form(Insert B) are the

time frames that the Agency is allowing for the submission of completed study reports or

protocols. The noted deadlines run from the date of the receipt of this Notice by the registrant. If

the data are not submitted by the deadline, each registrant is subject to receipt of a Notice of

Intent to Suspend the affected registration(s).

If you cannot submit the data/reports to the Agency in the time required by this Notice and

intend to seek additional time to meet the requirements(s), you must submit a request to the

Agency which includes: (1) a detailed description of the expected difficulty and (2) a proposed

schedule including alternative dates for meeting such requirements on a step-by-step basis. You

must explain any technical or laboratory difficulties and provide documentation from the

laboratory performing the testing. While EPA is considering your request, the original deadline

remains. The Agency will respond to your request in writing. If EPA does not grant your request,

the original deadline remains. Normally, extensions can be requested only in cases of

extraordinary testing problems beyond the expectation or control of the registrant. Extensions will

not be given in submitting the 90-day responses. Extensions will not be considered if the request

for extension is not made in a timely fashion; in no event shall an extension request be considered

if it is submitted at or after the lapse of the subject deadline.

Option 2. Agreement to Share in Cost to Develop Data

If you choose to enter into an agreement to share in the cost of producing the required data but

will not be submitting the data yourself, you must provide the name of the registrant who will be

submitting the data. You must also provide EPA with documentary evidence that an agreement

has been formed. Such evidence may be your letter offering to join in an agreement and the other

registrant's acceptance of your offer, or a written statement by the parties that an agreement

exists. The agreement to produce the data need not specify all of the terms of the final

arrangement between the parties or the mechanism to resolve the terms. Section 3(c)(2)(B)

provides that if the parties cannot resolve the terms of the agreement they may resolve their

differences through binding arbitration.

Option 3. Offer to Share in the Cost of Data Development

If you have made an offer to pay in an attempt to enter into an agreement or amend an existing

agreement to meet the requirements of this Notice and have been unsuccessful, you may request
268

EPA (by selecting this option) to exercise its discretion not to suspend your registration(s),

although you did not comply with the data submission requirements of this Notice. EPA has

determined that as a general policy, absent other relevant considerations, it will not suspend the

registration of a product of a registrant who has in good faith sought and continues to seek to

enter into a joint data development/cost sharing program, but the other registrant(s) developing

the data has refused to accept the offer. To qualify for this option, you must submit

documentation to the Agency proving that you have made an offer to another registrant (who has

an obligation to submit data) to share in the burden of developing that data. You must also submit

to the Agency a completed Certification with Respect to Citations of Data (in PR Notice 98-5)

(EPA Form 8570-34) . In addition, you must demonstrate that the other registrant to whom the

offer was made has not accepted your offer to enter into a cost-sharing agreement by including a

copy of your offer and proof of the other registrant's receipt of that offer (such as a certified mail

receipt). Your offer must, in addition to anything else, offer to share in the burden of producing

the data upon terms to be agreed to or, failing agreement, to be bound by binding arbitration as

provided by FIFRA section 3(c)(2)(B)(iii) and must not qualify this offer. The other registrant

must also inform EPA of its election of an option to develop and submit the data required by this

Notice by submitting a Data Call-In Response Form(Insert A) and a Requirements Status and

Registrant's Response Form(Insert B) committing to develop and submit the data required by this

Notice.

In order for you to avoid suspension under this option, you may not withdraw your offer to

share in the burden of developing the data. In addition, the other registrant must fulfill its

commitment to develop and submit the data as required by this Notice. If the other registrant fails

to develop the data or for some other reason is subject to suspension, your registration as well as

that of the other registrant normally will be subject to initiation of suspension proceedings, unless

you commit to submit, and do submit, the required data in the specified time frame. In such cases,

the Agency generally will not grant a time extension for submitting the data.

Option 4. Submitting an Existing Study

If you choose to submit an existing study in response to this Notice, you must determine that

the study satisfies the requirements imposed by this Notice. You may only submit a study that has

not been previously submitted to the Agency or previously cited by anyone. Existing studies are

studies which predate issuance of this Notice. Do not use this option if you are submitting data to

upgrade a study. (See Option 5).

You should be aware that if the Agency determines that the study is not acceptable, the Agency

will require you to comply with this Notice, normally without an extension of the required date of

submission. The Agency may determine at any time that a study is not valid and needs to be

repeated.

To meet the requirements of the DCI Notice for submitting an existing study, all of the

following three criteria must be clearly met:
269

a. You must certify at the time that the existing study is submitted that the raw data and

specimens from the study are available for audit and review and you must identify where

they are available. This must be done in accordance with the requirements of the Good

Laboratory Practice (GLP) regulation, 40 CFR Part 160. As stated in 40 CFR 160.3,

Raw data means any laboratory worksheets, records, memoranda, notes, or exact copies

thereof, that are the result of original observations and activities of a study and are

necessary for the reconstruction and evaluation of the report of that study. In the event

that exact transcripts of raw data have been prepared (e.g., tapes which have been

transcribed verbatim, dated, and verified accurate by signature), the exact copy or exact

transcript may be substituted for the original source as raw data. 'Raw data' may include

photographs, microfilm or microfiche copies, computer printouts, magnetic media,

including dictated observations, and recorded data from automated instruments." The

term "specimens", according to 40 CFR 160.3, means "any material derived from a test

system for examination or analysis."

b. Health and safety studies completed after May 1984 must also contain all GLP-required

quality assurance and quality control information pursuant to the requirements of 40

CFR Part 160. Registrants also must certify at the time of submission of the existing

study that such GLP information is available for post May 1984 studies by including an

appropriate statement on or attached to the study signed by an authorized official or

representative of the registrant.

c. You must certify that each study fulfills the acceptance criteria for the Guideline relevant

to the study provided in the FIFRA Accelerated Reregistration Phase 3 Technical

Guidance and that the study has been conducted according to the Pesticide Assessment

Guidelines (PAG) or meets the purpose of the PAG (both documents available from

NTIS). A study not conducted according to the PAG may be submitted to the Agency

for consideration if the registrant believes that the study clearly meets the purpose of the

PAG. The registrant is referred to 40 CFR 158.70 which states the Agency's policy

regarding acceptable protocols. If you wish to submit the study, you must, in addition to

certifying that the purposes of the PAG are met by the study, clearly articulate the

rationale why you believe the study meets the purpose of the PAG, including copies of

any supporting information or data. It has been the Agency's experience that studies

completed prior to January 1970 rarely satisfied the purpose of the PAG and that

necessary raw data usually are not available for such studies.

If you submit an existing study, you must certify that the study meets all requirements of the

criteria outlined above.

If EPA has previously reviewed a protocol for a study you are submitting, you must identify any

action taken by the Agency on the protocol and must indicate, as part of your certification, the

manner in which all Agency comments, concerns, or issues were addressed in the final protocol

and study.
270

If you know of a study pertaining to any requirement in this Notice which does not meet the

criteria outlined above but does contain factual information regarding unreasonable adverse

effects, you must notify the Agency of such a study. If such a study is in the Agency's files, you

need only cite it along with the notification. If not in the Agency's files, you must submit a

summary and copies as required by PR Notice 86-5 entitled "Standard Format for Data Submitted

under FIFRA".

Option 5. Upgrading a Study

If a study has been classified as partially acceptable and upgradeable, you may submit data to

upgrade that study. The Agency will review the data submitted and determine if the requirement is

satisfied. If the Agency decides the requirement is not satisfied, you may still be required to

submit new data normally without any time extension. Deficient, but upgradeable studies will

normally be classified as supplemental. However, it is important to note that not all studies

classified as supplemental are upgradeable. If you have questions regarding the classification of a

study or whether a study may be upgraded, call or write the contact person listed in Attachment 1.

If you submit data to upgrade an existing study you must satisfy or supply information to correct

all deficiencies in the study identified by EPA. You must provide a clearly articulated rationale of

how the deficiencies have been remedied or corrected and why the study should be rated as

acceptable to EPA. Your submission must also specify the MRID number(s) of the study which

you are attempting to upgrade and must be in conformance with PR Notice 86-5 entitled

"Standard Format for Data Submitted under FIFRA."

Do not submit additional data for the purpose of upgrading a study classified as unacceptable

and determined by the Agency as not capable of being upgraded.

This option also should be used to cite data that has been previously submitted to upgrade a

study, but has not yet been reviewed by the Agency. You must provide the MRID number of the

data submission as well as the MRID number of the study being upgraded.

The criteria for submitting an existing study, as specified in Option 4 above, apply to all data

submissions intended to upgrade studies. Additionally, your submission of data intended to

upgrade studies must be accompanied by a certification that you comply with each of those

criteria, as well as a certification regarding protocol compliance with Agency requirements.

Option 6. Citing Existing Studies

If you choose to cite a study that has been previously submitted to EPA, that study must have

been previously classified by EPA as acceptable, or it must be a study which has not yet been

reviewed by the Agency. Acceptable toxicology studies generally will have been classified as

"core-guideline" or "core-minimum." For ecological effects studies, the classification generally

would be a rating of "core." For all other disciplines the classification would be "acceptable." With

respect to any studies for which you wish to select this option, you must provide the MRID

number of the study you are citing and, if the study has been reviewed by the Agency, you must

provide the Agency's classification of the study.
271

If you are citing a study of which you are not the original data submitter, you must submit a

completed copy of EPA Form No. 8570-34, Certification with Respect to Citations of Data.

2. Product Specific Data

If you acknowledge on the product specific Data Call-In Response Form(Insert A) that you

agree to satisfy the product specific data requirements (i.e. you select option 7a or 7b), then you

must select one of the six options on the Requirements Status and Registrant’s Response

Form(Insert B) related to data production for each data requirement. Your option selection

should be entered under item number 9, "Registrant Response." The six options related to data

production are the first six options discussed under item 9 in the instructions for completing the

Requirements Status and Registrant's Response Form(Insert B). These six options are listed

immediately below with information in parentheses to guide registrants to additional instructions

provided in this Section. The options are:

(1) I will generate and submit data within the specified time-frame (Developing Data)

(2) I have entered into an agreement with one or more registrants to develop data jointly

(Cost Sharing) 

(3) I have made offers to cost-share (Offers to Cost Share)

(4) I am submitting an existing study that has not been submitted previously to the Agency

by anyone (Submitting an Existing Study) 

(5) I am submitting or citing data to upgrade a study classified by EPA as partially

acceptable and upgradeable (Upgrading a Study)

(6) I am citing an existing study that EPA has classified as acceptable or an existing study

that has been submitted but not reviewed by the Agency (Citing an Existing Study)

Option 1. Developing Data -- The requirements for developing product specific data are the same

as those described for generic data (see Section III.C.1, Option 1) except that normally no

protocols or progress reports are required.

Option 2. Agree to Share in Cost to Develop Data -- If you enter into an agreement to cost share,

the same requirements apply to product specific data as to generic data (see Section III.C.1,

Option 2). However, registrants may only choose this option for acute toxicity data and certain

efficacy data and only if EPA has indicated in the attached data tables that your product and at

least one other product are similar for purposes of depending on the same data. If this is the case,

data may be generated for just one of the products in the group. The registration number of the

product for which data will be submitted must be noted in the agreement to cost share by the

registrant selecting this option.

Option 3. Offer to Share in the Cost of Data Development --The same requirements for generic

data (Section III.C.I., Option 3) apply to this option. This option only applies to acute toxicity

and certain efficacy data as described in option 2 above.

Option 4. Submitting an Existing Study -- The same requirements described for generic data (see

Section III.C.1., Option 4) apply to this option for product specific data.
272

Option 5. Upgrading a Study -- The same requirements described for generic data (see Section

III.C.1., Option 5) apply to this option for product specific data.

Option 6. Citing Existing Studies -- The same requirements described for generic data (see

Section III.C.1., Option 6) apply to this option for product specific data.

Registrants who select one of the above 6 options must meet all of the requirements described

in the instructions for completing the Data Call-In Response Form(Insert A) and the

Requirements Status and Registrant's Response Form(Insert B), and in the generic data

requirements section (III.C.1.), as appropriate.

III-D REQUESTS FOR DATA WAIVERS

1. Generic Data

There are two types of data waiver responses to this Notice. The first is a request for a low

volume/minor use waiver and the second is a waiver request based on your belief that the data

requirement(s) are not appropriate for your product.

a. Low Volume/Minor Use Waiver

Option 8 under item 9 on the Requirements Status and Registrant's Response

Form(Insert B). Section 3(c)(2)(A) of FIFRA requires EPA to consider the appropriateness of

requiring data for low volume/minor use pesticides. In implementing this provision, EPA

considers low volume pesticides to be only those active ingredients whose total production

volume for all pesticide registrants is small. In determining whether to grant a low volume,

minor use waiver, the Agency will consider the extent, pattern and volume of use, the economic

incentive to conduct the testing, the importance of the pesticide, and the exposure and risk from

use of the pesticide. If an active ingredient is used for both high volume and low volume uses, a

low volume exemption will not be approved. If all uses of an active ingredient are low volume

and the combined volumes for all uses are also low, then an exemption may be granted,

depending on review of other information outlined below. An exemption will not be granted if

any registrant of the active ingredient elects to conduct the testing. Any registrant receiving a

low volume/minor use waiver must remain within the sales figures in their forecast supporting

the waiver request in order to remain qualified for such waiver. If granted a waiver, a registrant

will be required, as a condition of the waiver, to submit annual sales reports. The Agency will

respond to requests for waivers in writing.

To apply for a low volume/minor use waiver, you must submit the following information, as

applicable to your product(s), as part of your 90-day response to this Notice:

(i). Total company sales (pounds and dollars) of all registered product(s) containing the

active ingredient. If applicable to the active ingredient, include foreign sales for those products

that are not registered in this country but are applied to sugar (cane or beet), coffee, bananas,
273

cocoa, and other such crops. Present the above information by year for each of the past five

years.

(ii) Provide an estimate of the sales (pounds and dollars) of the active ingredient for

each major use site. Present the above information by year for each of the past five years.

(iii) Total direct production cost of product(s) containing the active ingredient by year

for the past five years. Include information on raw material cost, direct labor cost, advertising,

sales and marketing, and any other significant costs listed separately.

(iv) Total indirect production cost (e.g. plant overhead, amortized plant and equipment)

charged to product(s) containing the active ingredient by year for the past five years. Exclude all

non-recurring costs that were directly related to the active ingredient, such as costs of initial

registration and any data development.

(v) A list of each data requirement for which you seek a waiver. Indicate the type of

waiver sought and the estimated cost to you (listed separately for each data requirement and

associated test) of conducting the testing needed to fulfill each of these data requirements.

(vi) A list of each data requirement for which you are not seeking any waiver and the

estimated cost to you (listed separately for each data requirement and associated test) of

conducting the testing needed to fulfill each of these data requirements.

(vii) For each of the next ten years, a year-by-year forecast of company sales (pounds

and dollars) of the active ingredient, direct production costs of product(s) containing the active

ingredient (following the parameters in item 2 above), indirect production costs of product(s)

containing the active ingredient (following the parameters in item 3 above), and costs of data

development pertaining to the active ingredient.

(viii) A description of the importance and unique benefits of the active ingredient to

users. Discuss the use patterns and the effectiveness of the active ingredient relative to

registered alternative chemicals and non-chemical control strategies. Focus on benefits unique to

the active ingredient, providing information that is as quantitative as possible. If you do not have

quantitative data upon which to base your estimates, then present the reasoning used to derive

your estimates. To assist the Agency in determining the degree of importance of the active

ingredient in terms of its benefits, you should provide information on any of the following

factors, as applicable to your product(s): (a) documentation of the usefulness of the active

ingredient in Integrated Pest Management, (b) description of the beneficial impacts on the

environment of use of the active ingredient, as opposed to its registered alternatives, (c)

information on the breakdown of the active ingredient after use and on its persistence in the

environment, and (d) description of its usefulness against a pest(s) of public health significance.

Failure to submit sufficient information for the Agency to make a determination

regarding a request for a low volume/minor use waiver will result in denial of the request for a

waiver.
274

b. Request for Waiver of Data

Option 9, under Item 9, on the Requirements Status and Registrant's Response Form.

This option may be used if you believe that a particular data requirement should not apply

because the requirement is inappropriate. You must submit a rationale explaining why you

believe the data requirements should not apply. You also must submit the current label(s) of

your product(s) and, if a current copy of your Confidential Statement of Formula is not already

on file you must submit a current copy.

You will be informed of the Agency's decision in writing. If the Agency determines that

the data requirements of this Notice are not appropriate to your product(s), you will not be

required to supply the data pursuant to section 3(c)(2)(B). If EPA determines that the data are

required for your product(s), you must choose a method of meeting the requirements of this

Notice within the time frame provided by this Notice. Within 30 days of your receipt of the

Agency's written decision, you must submit a revised Requirements Status and Registrant's

Response Form indicating the option chosen.

2. Product Specific Data

If you request a waiver for product specific data because you believe it is inappropriate,

you must attach a complete justification for the request including technical reasons, data and

references to relevant EPA regulations, guidelines or policies. (Note: any supplemental data

must be submitted in the format required by PR Notice 86-5). This will be the only opportunity

to state the reasons or provide information in support of your request. If the Agency approves

your waiver request, you will not be required to supply the data pursuant to section 3(c)(2)(B)

of FIFRA. If the Agency denies your waiver request, you must choose an option for meeting the

data requirements of this Notice within 30 days of the receipt of the Agency's decision. You

must indicate and submit the option chosen on the product specific Requirements Status and

Registrant's Response Form(Insert B). Product specific data requirements for product

chemistry, acute toxicity and efficacy (where appropriate) are required for all products and the

Agency would grant a waiver only under extraordinary circumstances. You should also be

aware that submitting a waiver request will not automatically extend the due date for the study

in question. Waiver requests submitted without adequate supporting rationale will be denied and

the original due date will remain in force.

SECTION IV. CONSEQUENCES OF FAILURE TO COMPLY WITH THIS NOTICE

IV-A NOTICE OF INTENT TO SUSPEND

The Agency may issue a Notice of Intent to Suspend products subject to this Notice due to

failure by a registrant to comply with the requirements of this Data Call-In Notice, pursuant to

FIFRA section 3(c)(2)(B). Events which may be the basis for issuance of a Notice of Intent to

Suspend include, but are not limited to, the following:
275

1. Failure to respond as required by this Notice within 90 days of your receipt of this

Notice.

2. Failure to submit on the required schedule an acceptable proposed or final protocol

when such is required to be submitted to the Agency for review.

3. Failure to submit on the required schedule an adequate progress report on a study as

required by this Notice.

4. Failure to submit on the required schedule acceptable data as required by this Notice.

5. Failure to take a required action or submit adequate information pertaining to any option

chosen to address the data requirements (e.g., any required action or information

pertaining to submission or citation of existing studies or offers, arrangements, or

arbitration on the sharing of costs or the formation of Task Forces, failure to comply

with the terms of an agreement or arbitration concerning joint data development or

failure to comply with any terms of a data waiver).

6. Failure to submit supportable certifications as to the conditions of submitted studies, as

required by Section III-C of this Notice.

7. Withdrawal of an offer to share in the cost of developing required data.

8. Failure of the registrant to whom you have tendered an offer to share in the cost of

developing data and provided proof of the registrant's receipt of such offer or failure of a

registrant on whom you rely for a generic data exemption either to:

a. Inform EPA of intent to develop and submit the data required by this Notice on a

Data Call-In Response Form(Insert A) and a Requirements Status and Registrant’s

Response Form(Insert B).

b. Fulfill the commitment to develop and submit the data as required by this Notice; or

c. Otherwise take appropriate steps to meet the requirements stated in this Notice,

unless you commit to submit and do submit the required data in the specified time frame.

9. Failure to take any required or appropriate steps, not mentioned above, at any time

following the issuance of this Notice.
276

IV-B. BASIS FOR DETERMINATION THAT SUBMITTED STUDY IS

UNACCEPTABLE

The Agency may determine that a study (even if submitted within the required time) is

unacceptable and constitutes a basis for issuance of a Notice of Intent to Suspend. The grounds

for suspension include, but are not limited to, failure to meet any of the following:

1) EPA requirements specified in the Data Call-In Notice or other documents incorporated

by reference (including, as applicable, EPA Pesticide Assessment Guidelines, Data Reporting

Guidelines, and GeneTox Health Effects Test Guidelines) regarding the design, conduct, and

reporting of required studies. Such requirements include, but are not limited to, those relating to

test material, test procedures, selection of species, number of animals, sex and distribution of

animals, dose and effect levels to be tested or attained, duration of test, and, as applicable, Good

Laboratory Practices.

2) EPA requirements regarding the submission of protocols, including the incorporation of

any changes required by the Agency following review.

3) EPA requirements regarding the reporting of data, including the manner of reporting,

the completeness of results, and the adequacy of any required supporting (or raw) data,

including, but not limited to, requirements referenced or included in this Notice or contained in

PR 86-5. All studies must be submitted in the form of a final report; a preliminary report will not

be considered to fulfill the submission requirement.

IV-C EXISTING STOCKS OF SUSPENDED OR CANCELLED PRODUCTS

EPA has statutory authority to permit continued sale, distribution and use of existing stocks of a

pesticide product which has been suspended or cancelled if doing so would be consistent with the

purposes of the Act.

The Agency has determined that such disposition by registrants of existing stocks for a

suspended registration when a section 3(c)(2)(B) data request is outstanding generally would not

be consistent with the Act's purposes. Accordingly, the Agency anticipates granting registrants

permission to sell, distribute, or use existing stocks of suspended product(s) only in exceptional

circumstances. If you believe such disposition of existing stocks of your product(s) which may be

suspended for failure to comply with this Notice should be permitted, you have the burden of

clearly demonstrating to EPA that granting such permission would be consistent with the Act.

You also must explain why an "existing stocks" provision is necessary, including a statement of

the quantity of existing stocks and your estimate of the time required for their sale, distribution,

and use. Unless you meet this burden, the Agency will not consider any request pertaining to the

continued sale, distribution, or use of your existing stocks after suspension.

If you request a voluntary cancellation of your product(s) as a response to this Notice and your

product is in full compliance with all Agency requirements, you will have, under most

circumstances, one year from the date your 90 day response to this Notice is due, to sell,
277

distribute, or use existing stocks. Normally, the Agency will allow persons other than the

registrant such as independent distributors, retailers and end users to sell, distribute or use such

existing stocks until the stocks are exhausted. Any sale, distribution or use of stocks of voluntarily

cancelled products containing an active ingredient for which the Agency has particular risk

concerns will be determined on a case-by-case basis.

Requests for voluntary cancellation received after the 90 day response period required by this

Notice will not result in the agency granting any additional time to sell, distribute, or use existing

stocks beyond a year from the date the 90 day response was due, unless you demonstrate to the

Agency that you are in full compliance with all Agency requirements, including the requirements

of this Notice. For example, if you decide to voluntarily cancel your registration six months before

a 3-year study is scheduled to be submitted, all progress reports and other information necessary

to establish that you have been conducting the study in an acceptable and good faith manner must

have been submitted to the Agency, before EPA will consider granting an existing stocks

provision.

SECTION V. REGISTRANTS' OBLIGATION TO REPORT POSSIBLE

UNREASONABLE ADVERSE EFFECTS

Registrants are reminded that FIFRA section 6(a)(2) states that if at any time after a pesticide is

registered a registrant has additional factual information regarding unreasonable adverse effects

on the environment by the pesticide, the registrant shall submit the information to the Agency.

Registrants must notify the Agency of any factual information they have, from whatever source,

including but not limited to interim or preliminary results of studies, regarding unreasonable

adverse effects on man or the environment. This requirement continues as long as the products

are registered by the Agency.

SECTION VI. INQUIRIES AND RESPONSES TO THIS NOTICE

If you have any questions regarding the requirements and procedures established by this Notice,

call the contact person(s) listed in Attachment 1, the Data Call-In Chemical Status Sheet.

All responses to this Notice must include completed Data Call-In Response Forms (Insert A)and

completed Requirements Status and Registrant's Response Forms (Insert B), for both (generic and

product specific data) and any other documents required by this Notice, and should be submitted

to the contact person(s) identified in Attachment 1. If the voluntary cancellation or generic data

exemption option is chosen, only the Generic and Product Specific Data Call-In Response

Forms(Insert A) need be submitted.
278

The Office of Compliance (OC) of the Office of Enforcement and Compliance Assurance

(OECA), EPA, will be monitoring the data being generated in response to this Notice.

Sincerely yours,

Lois A. Rossi, Director 

Special Review and

 Reregistration Division

Attachments

The Attachments to this Notice are:

1 - Data Call-In Chemical Status Sheet

2 - Generic Data Call-In and Product Specific Data Call-In Response Forms with

Instructions

3 - Generic Data Call-In and Product Specific Data Call-In Requirements Status and

Registrant's Response Forms with Instructions

4 - EPA Batching of End-Use Products for Meeting Acute Toxicology Data Requirements

for Reregistration

5 - List of Registrants Receiving This Notice

1.Chemical Status Sheets
279

ALACHLOR DATA CALL-IN CHEMICAL STATUS SHEET

INTRODUCTION

You have been sent this Product Specific Data Call-In Notice because you have

product(s) containing alachlor.

This Product Specific Data Call-In Chemical Status Sheet, contains an overview of data

required by this notice, and point of contact for inquiries pertaining to the reregistration

of alachlor. This attachment is to be used in conjunction with (1) the Product Specific

Data Call-In Notice, (2) the Product Specific Data Call-In Response Form (Attachment

2), (3) the Requirements Status and Registrant's Form (Attachment 3), (4) EPA's

Grouping of End-Use Products for Meeting Acute Toxicology Data Requirement

(Attachment 4), (5) the EPA Acceptance Criteria (Attachment 5), (6) a list of registrants

receiving this DCI (Attachment 6) and (7) the Cost Share and Data Compensation Forms

in replying to this alachlor Product Specific Data Call-In (Attachment 7). Instructions and

guidance accompany each form.

DATA REQUIRED BY THIS NOTICE

The additional data requirements needed to complete the database for alachlor are

contained in the Requirements Status and Registrant's Response, Attachment 3. The

Agency has concluded that additional data on alachlor are needed for specific products.

These data are required to be submitted to the Agency within the time frame listed. These

data are needed to fully complete the reregistration of all eligible alachlor products.

INQUIRIES AND RESPONSES TO THIS NOTICE

If you have any questions regarding this product specific data requirements and

procedures established by this Notice, please contact Veronica Dutch at (703) 308-8585.

All responses to this Notice for the Product Specific data requirements should be

submitted to:

Veronica Dutch

Chemical Review Manager Team 81

Product Reregistration Branch

Special Review and Reregistration Branch 7508C

Office of Pesticide Programs

U.S. Environmental Protection Agency

Washington, D.C. 20460

RE: alachlor
280

ALACHLOR DATA CALL-IN CHEMICAL STATUS SHEET

INTRODUCTION

You have been sent this Generic Data Call-In Notice because you have product(s)

containing alachlor.

This Generic Data Call-In Chemical Status Sheet, contains an overview of data required

by this notice, and point of contact for inquiries pertaining to the reregistration of alachlor.

This attachment is to be used in conjunction with (1) the Generic Data Call-In Notice, (2)

the Generic Data Call-In Response Form (Attachment 2), (3) the Requirements Status and

Registrant's Form (Attachment 2), (4) a list of registrants receiving this DCI (Attachment

4), (5) the EPA Acceptance Criteria (Attachment 5), and (6) the Cost Share and Data

Compensation Forms in replying to this alachlor Generic Data Call In (Attachment F).

Instructions and guidance accompany each form.

DATA REQUIRED BY THIS NOTICE

The additional data requirements needed to complete the generic database for alachlor

are contained in the Requirements Status and Registrant's Response, Attachment C. The

Agency has concluded that additional product chemistry data on alachlor are needed.

These data are needed to fully complete the reregistration of all eligible alachlor products.

INQUIRIES AND RESPONSES TO THIS NOTICE

If you have any questions regarding the generic data requirements and procedures

established by this Notice, please contact Kathryn Boyle at (703) 305-6304.

All responses to this Notice for the generic data requirements should be submitted to:

Kathryn Boyle, Chemical Review Manager 

Reregistration Branch III

Special Review and Registration Division (7508C)

Office of Pesticide Programs

U.S. Environmental Protection Agency

Washington, D.C. 20460

RE: alachlor
281

2.Combined Generic and Product Specific Data Call-In Response Forms (Insert A) Plus Instructions

This page has been inserted as a place marker and is replaced by an electronically

generated PDCI sample Part A form page number 1 in the actual Printed version of the

Red document
282

This page has been inserted as a place marker and is replaced by an electronically

generated PDCI sample Part A form page number 1 in the actual Printed version of the

Red document
283

This page has been inserted as a place marker and is replaced by an electronically

generated PDCI sample Part A form page number 1 in the actual Printed version of the

Red document
284
285

Instructions For Completing The "Data Call-In Response Forms" For The

Generic And Product Specific Data Call-In

INTRODUCTION

These instructions apply to the Generic and Product Specific "Data Call-In Response

Forms" (Insert A) and are to be used by registrants to respond to generic and product

specific Data Call-Ins as part of EPA's Reregistration Program under the Federal

Insecticide, Fungicide, and Rodenticide Act. If you are an end-use product registrant

only and have been sent this DCI letter as part of a RED document you have been sent

just the product specific "Data Call-In Response Forms."(Insert A) Only registrants

responsible for generic data have been sent the generic data response form. The type

of Data Call-In (generic or product specific) is indicated in item number 3 ("Date

and Type of DCI") on each form.

Although the form is the same for both generic and product specific data, instructions

for completing these forms are different. Please read these instructions carefully before

filling out the forms.

EPA has developed these forms individually for each registrant, and has preprinted

these forms with a number of items. DO NOT use these forms for any other active

ingredient.

Items 1 through 4 have been preprinted on the form. Items 5 through 7 must be

completed by the registrant as appropriate. Items 8 through 11 must be completed by

the registrant before submitting a response to the Agency.

The public reporting burden for this collection of information is estimated to average

15 minutes per response, including time for reviewing instructions, searching existing

data sources, gathering and maintaining the data needed, and completing and reviewing

the collection of information. Send comments regarding the burden estimate or any

other aspect of this collection of information, including suggestions for reducing this

burden, to Chief, Information Policy Branch, Mail Code 2137, U.S. Environmental

Protection Agency, 401 M St., S.W., Washington, D.C. 20460; and to the Office of

Management and Budget, Paperwork Reduction Project 2070-0107, Washington, D.C.

20503.
286

INSTRUCTIONS FOR COMPLETING THE DATA CALL-IN RESPONSE

FORMS

INSERT A

Generic and Product Specific Data Call-In

Item 1. ON BOTH FORMS: This item identifies your company name, number and

address.

Item 2. ON BOTH FORMS: This item identifies the case number, case name, EPA

chemical number and chemical name.

Item 3. ON BOTH FORMS: This item identifies the type of Data Call-In. The date

of issuance is date stamped.

Item 4. ON BOTH FORMS: This item identifies the EPA product registrations

relevant to the data call-in. Please note that you are also responsible for

informing the Agency of your response regarding any product that you

believe may be covered by this Data Call-In but that is not listed by the

Agency in Item 4. You must bring any such apparent omission to the

Agency's attention within the period required for submission of this response

form.

Item 5. ON BOTH FORMS: Check this item for each product registration you wish

to cancel voluntarily. If a registration number is listed for a product for which

you previously requested voluntary cancellation, indicate in Item 5 the date of

that request. Since this Data Call-In requires both generic and product

specific data, you must complete item 5 on both Data Call-In response forms. 

You do not need to complete any item on the Requirements Status and

Registrant's Response Forms (Insert B) 

Item 6a. ON THE GENERIC DATA FORM: Check this Item if the Data Call-In is

for generic data as indicated in Item 3 and you are eligible for a Generic Data

Exemption for the chemical listed in Item 2 and used in the subject product. 

By electing this exemption, you agree to the terms and conditions of a

Generic Data Exemption as explained in the Data Call-In Notice.

If you are eligible for or claim a Generic Data Exemption, enter the EPA

registration Number of each registered source of that active ingredient that

you use in your product.
287

Typically, if you purchase an EPA-registered product from one or more other

producers (who, with respect to the incorporated product, are in compliance

with this and any other outstanding Data Call-In Notice), and incorporate that

product into all your products, you may complete this item for all products

listed on this form. If, however, you produce the active ingredient yourself, or

use any unregistered product (regardless of the fact that some of your sources

are registered), you may not claim a Generic Data Exemption and you may

not select this item.

INSTRUCTIONS FOR COMPLETING THE DATA CALL-IN RESPONSE

FORMS

INSERT B

Generic and Product Specific Data Call-In

Item 6b. ON THE GENERIC DATA FORM: Check this Item if the Data Call-In is

for generic data as indicated in Item 3 and if you are agreeing to satisfy the

generic data requirements of this Data Call-In. Attach the Requirements

Status and Registrant's Response Form(Insert B) that indicates how you will

satisfy those requirements.

NOTE: Item 6a and 6b are not applicable for Product Specific Data.

Item 7a. ON THE PRODUCT SPECIFIC DATA FORM: For each manufacturing

use product (MUP) for which you wish to maintain registration, you must

agree to satisfy the data requirements by responding "yes."

Item 7b. For each end use product (EUP) for which you wish to maintain registration,

you must agree to satisfy the data requirements by responding "yes." 

FOR BOTH MUP and EUP products

You should also respond "yes" to this item (7a for MUP's and 7b for EUP's) if

your product is identical to another product and you qualify for a data

exemption. You must provide the EPA registration numbers of your

source(s); do not complete the Requirements Status and Registrant's

Response form. Examples of such products include repackaged products and

Special Local Needs (Section 24c) products which are identical to federally

registered products.
288

If you are requesting a data waiver, answer "yes" here; in addition, on the

"Requirements Status and Registrant's Response" form under Item 9, you

must respond with option 7 (Waiver Request) for each study for which you

are requesting a waiver. 

NOTE: Item 7a and 7b are not applicable for Generic Data.
289

INSTRUCTIONS FOR COMPLETING THE DATA CALL-IN RESPONSE

FORMS

INSERT B CONTINUED

Generic and Product Specific Data Call-In

Item 8. ON BOTH FORMS: This certification statement must be signed by an

authorized representative of your company and the person signing must

include his/her title. Additional pages used in your response must be initialed

and dated in the space provided for the certification.

Item 9. ON BOTH FORMS: Enter the date of signature.

Item 10. ON BOTH FORMS: Enter the name of the person EPA should contact

with questions regarding your response.

Item 11. ON BOTH FORMS: Enter the phone number of your company contact.

Note: You may provide additional information that does not fit on this form in a signed letter that accompanies your response. For example,

you may wish to report that your product has already been transferred to another company or that you have already voluntarily canceled

this product. For these cases, please supply all relevant details so that EPA can ensure that its records are correct.
290

3.Generic and Product Specific Requirement Status and Registrant's Response Forms (Insert B) and Instructions

This page has been inserted as a place marker and is replaced by an electronically

generated PDCI sample Part B form page number 1 in the actual Printed version of the

Red document
291

This page has been inserted as a place marker and is replaced by an electronically

generated PDCI sample Part B form page number 2 in the actual Printed version of the

Red document
292

This page has been inserted as a place marker and is replaced by an electronically

generated PDCI sample Part B form page number 3 in the actual Printed version of the

Red document
293

This page has been inserted as a place marker and is replaced by an electronically

generated PDCI sample Part B form page number 4 in the actual Printed version of the

Red document
294
295

Instructions For Completing The "Requirements Status and Registrant's

Response Forms" (Insert B) For The Generic and Product Specific Data Call-In

INTRODUCTION

These instructions apply to the Generic and Product Specific "Requirements Status

and Registrant's Response Forms" and are to be used by registrants to respond to

generic and product specific Data Call-In's as part of EPA's reregistration program

under the Federal Insecticide, Fungicide, and Rodenticide Act. If you are an end-use

product registrant only and have been sent this DCI letter as part of a RED document

you have been sent just the product specific "Requirements Status and Registrant's

Response Forms." Only registrants responsible for generic data have been sent the

generic data response forms. The type of Data Call-In (generic or product specific)

is indicated in item number 3 ("Date and Type of DCI") on each form.

Although the form is the same for both product specific and generic data, instructions

for completing the forms differ slightly. Specifically, options for satisfying product

specific data requirements do not include (1) deletion of uses or (2) request for a low

volume/minor use waiver. Please read these instructions carefully before filling out the

forms. 

EPA has developed these forms individually for each registrant, and has preprinted

these forms to include certain information unique to this chemical. DO NOT use these

forms for any other active ingredient.

Items 1 through 8 have been preprinted on the form. Item 9 must be completed by

the registrant as appropriate. Items 10 through 13 must be completed by the registrant

before submitting a response to the Agency. 

The public reporting burden for this collection of information is estimated to average

30 minutes per response, including time for reviewing instructions, searching existing

data sources, gathering and maintaining the data needed, and completing and reviewing

the collection of information. Send comments regarding the burden estimate or any

other aspect of this collection of information, including suggestions for reducing this

burden, to Chief, Information Policy Branch, Mail Code 2137, U.S. Environmental

Protection Agency, 401 M St., S.W., Washington, D.C. 20460; and to the Office of

Management and Budget, Paperwork Reduction Project 2070-0107, Washington, D.C.

20503.
296
297

INSTRUCTIONS FOR COMPLETING THE "REQUIREMENTS STATUS

AND REGISTRANT'S RESPONSE FORMS" (Insert B)

Generic and Product Specific Data Call-In

Item 1. ON BOTH FORMS: This item identifies your company name, number and

address.

Item 2. ON THE GENERIC DATA FORM: This item identifies the case number,

case name, EPA chemical number and chemical name.

ON THE PRODUCT SPECIFIC DATA FORM: This item identifies the 

case number, case name, and the EPA Registration Number of the product for

which the Agency is requesting product specific data. 

Item 3. ON THE GENERIC DATA FORM: This item identifies the type of Data

Call-In. The date of issuance is date stamped. 

ON THE PRODUCT SPECIFIC DATA FORM: This item identifies the

type of Data Call-In. The date of issuance is also date stamped. Note the

unique identifier number (ID#) assigned by the Agency. This ID number must

be used in the transmittal document for any data submissions in response to

this Data Call-In Notice.

Item 4. ON BOTH FORMS: This item identifies the guideline reference number of

studies required. These guidelines, in addition to the requirements specified in

the Data Call-In Notice, govern the conduct of the required studies. Note

that series 61 and 62 in product chemistry are now listed under 40 CFR

158.155 through 158.180, Subpart c.

Item 5. ON BOTH FORMS: This item identifies the study title associated with the

guideline reference number and whether protocols and 1, 2, or 3-year

progress reports are required to be submitted in connection with the study. 

As noted in Section III of the Data Call-In Notice, 90-day progress reports

are required for all studies.

If an asterisk appears in Item 5, EPA has attached information relevant to this

guideline reference number to the Requirements Status and Reqistrant's

Response Form(Insert B).
298

INSTRUCTIONS FOR COMPLETING THE "REQUIREMENTS STATUS

AND REGISTRANT'S RESPONSE FORMS" (Insert B) continued

Generic and Product Specific Data Call-In

Item 6. ON BOTH FORMS: This item identifies the code associated with the use

pattern of the pesticide. In the case of efficacy data (product specific 

requirement), the required study only pertains to products which have the use

sites and/or pests indicated. A brief description of each code follows:

A Terrestrial food

B Terrestrial feed

C Terrestrial non-food

D Aquatic food

E Aquatic non-food outdoor

F Aquatic non-food industrial

G Aquatic non-food residential

H Greenhouse food

I Greenhouse non-food crop

J Forestry

K Residential

L Indoor food

M Indoor non-food

N Indoor medical

O Indoor residential

Item 7. ON BOTH FORMS: This item identifies the code assigned to the substance

that must be used for testing. A brief description of each code follows: 

EUP End-Use Product

MP Manufacturing-Use Product

MP/TGAI Manufacturing-Use Product and Technical Grade

Active Ingredient

PAI Pure Active Ingredient

PAI/M Pure Active Ingredient and Metabolites

PAI/PAIRA Pure Active Indredient or Pute Active 

Ingredient Radiolabelled
299

PAIRA Pure Active Ingredient Radiolabelled

PAIRA/M Pure Active Ingredient Radiolabelled and Metabolites

PAIRA/PM Pure Active Ingredient Radiolabelled and Plant

Metabolites

TEP Typical End-Use Product

TEP ___% Typical End-Use Product, Percent Active Ingredient

Specified

TEP/MET Typical End-Use Product and Metabolites

TEP/PAI/M Typical End-Use Product or Pure Active Ingredient

and Metabolites

TGAI Technical Grade Active Ingredient

TGAI/PAI Technical Grade Active Ingredient or Pure Active

Ingredient

TGAI/PAIRA Technical Grade Active Ingredient or Pure Active

Ingredient Radiolabelled

TGAI/TEP Technical Grade Active Ingredient or Typical End-Use

Product

MET Metabolites

IMP Impurities

DEGR Degradates

* See: guideline comment

Item 8. This item completed by the Agency identifies the time frame allowed for

submission of the study or protocol identified in item 5. 

ON THE GENERIC DATA FORM: The time frame runs from the date of

your receipt of the Data Call-In notice.

ON THE PRODUCT SPECIFIC DATA FORM: The due date for

submission of product specific studies begins from the date stamped on the

letter transmitting the Reregistration Eligibility Decision document, and not

from the date of receipt. However, your response to the Data Call-In itself is

due 90 days from the date of receipt. 

Item 9. ON BOTH FORMS: Enter the appropriate Response Code or Codes to

show how you intend to comply with each data requirement. Brief

descriptions of each code follow. The Data Call-In Notice contains a fuller

description of each of these options.
300

Option 1. ON BOTH FORMS: (Developing Data) I will conduct a new study

and submit it within the time frames specified in item 8 above. By

indicating that I have chosen this option, I certify that I will comply

with all the requirements pertaining to the conditions for submittal of

this study as outlined in the Data Call-In Notice and that I will provide

the protocols and progress reports required in item 5 above.

Option 2. ON BOTH FORMS: (Agreement to Cost Share) I have entered into

an agreement with one or more registrants to develop data jointly. By

indicating that I have chosen this option, I certify that I will comply

with all the requirements pertaining to sharing in the cost of

developing data as outlined in the Data Call-In Notice.

However, for Product Specific Data, I understand that this

option is available for acute toxicity or certain efficacy data ONLY if

the Agency indicates in an attachment to this notice that my product is

similar enough to another product to qualify for this option. I certify

that another party in the agreement is committing to submit or provide

the required data; if the required study is not submitted on time, my

product may be subject to suspension.

Option 3. ON BOTH FORMS: (Offer to Cost Share) I have made an offer to

enter into an agreement with one or more registrants to develop data

jointly. I am also submitting a completed "Certification of offer to

Cost Share in the Development of Data" form. I am submitting

evidence that I have made an offer to another registrant (who has an

obligation to submit data) to share in the cost of that data. I am

including a copy of my offer and proof of the other registrant's receipt

of that offer. I am identifying the party which is committing to submit

or provide the required data; if the required study is not submitted on

time, my product may be subject to suspension. I understand that

other terms under Option 3 in the Data Call-In Notice apply as well.

However, for Product Specific Data, I understand that this

option is available only for acute toxicity or certain efficacy data and

only if the Agency indicates in an attachment to this Data Call-In

Notice that my product is similar enough to another product to qualify

for this option. 
301

Option 4. ON BOTH FORMS: (Submitting Existing Data) I will submit an

existing study by the specified due date that has never before been

submitted to EPA. By indicating that I have chosen this option, I

certify that this study meets all the requirements pertaining to the

conditions for submittal of existing data outlined in the Data Call-In

Notice and I have attached the needed supporting information along

with this response.

Option 5. ON BOTH FORMS: (Upgrading a Study) I will submit by the

specified due date, or will cite data to upgrade a study that EPA has

classified as partially acceptable and potentially upgradeable. By

indicating that I have chosen this option, I certify that I have met all

the requirements pertaining to the conditions for submitting or citing

existing data to upgrade a study described in the Data Call-In Notice.

I am indicating on attached correspondence the Master Record

Identification Number (MRID) that EPA has assigned to the data that

I am citing as well as the MRID of the study I am attempting to

upgrade.

Option 6. ON BOTH FORMS: (Citing a Study) I am citing an existing study

that has been previously classified by EPA as acceptable, core, core

minimum, or a study that has not yet been reviewed by the Agency. If

reviewed, I am providing the Agency's classification of the study.

However, for Product Specific Data, I am citing another

registrant's study. I understand that this option is available ONLY for

acute toxicity or certain efficacy data and ONLY if the cited study

was conducted on my product, an identical product or a product

which the Agency has "grouped" with one or more other products for

purposes of depending on the same data. I may also choose this option

if I am citing my own data. In either case, I will provide the MRID or

Accession number (s). If I cite another registrant's data, I will submit

a completed "Certification With Respect To Data Compensation

Requirements" form.

FOR THE GENERIC DATA FORM ONLY: The following three options

(Numbers 7, 8, and 9) are responses that apply only to the "Requirements

Status and Registrant's Response Form" (Insert B) for generic data. 
302

Option 7. (Deleting Uses) I am attaching an application for amendment to my

registration deleting the uses for which the data are required.

Option 8. (Low Volume/Minor Use Waiver Request) I have read the statements

concerning low volume-minor use data waivers in the Data Call-In

Notice and I request a low-volume minor use waiver of the data

requirement. I am attaching a detailed justification to support this

waiver request including, among other things, all information required

to support the request. I understand that, unless modified by the

Agency in writing, the data requirement as stated in the Notice

governs.

Option 9. (Request for Waiver of Data) I have read the statements concerning

data waivers other than lowvolume minor-use data waivers in the Data

Call-In Notice and I request a waiver of the data requirement. I am

attaching a rationale explaining why I believe the data requirements do

not apply. I am also submitting a copy of my current labels. (You must

also submit a copy of your Confidential Statement of Formula if not

already on file with EPA). I understand that, unless modified by the

Agency in writing, the data requirement as stated in the Notice

governs.

FOR PRODUCT SPECIFIC DATA: The following option (number 7) is a

response that applies to the "Requirements Status and Registrant's Response

Form" (Insert B) for product specific data. 

Option 7. (Waiver Request) I request a waiver for this study because it is

inappropriate for my product. I am attaching a complete justification

for this request, including technical reasons, data and references to

relevant EPA regulations, guidelines or policies. [Note: any

supplemental data must be submitted in the format required by P.R.

Notice 86-5]. I understand that this is my only opportunity to state the

reasons or provide information in support of my request. If the

Agency approves my waiver request, I will not be required to supply

the data pursuant to Section 3(c) (2) (B) of FIFRA. If the Agency

denies my waiver request, I must choose a method of meeting the data

requirements of this Notice by the due date stated by this Notice. In

this case, I must, within 30 days-of my receipt of the Agency's written

decision, submit a revised "Requirements Status" form specifying the
303

option chosen. I also understand that the deadline for submission of

data as specified by the original Data Call-In notice will not change.

Item 10. ON BOTH FORMS: This item must be signed by an authorized

representative of your company. The person signing must include his/her title,

and must initial and date all other pages of this form.

Item 11. ON BOTH FORMS: Enter the date of signature.

Item 12. ON BOTH FORMS: Enter the name of the person EPA should contact with

questions regarding your response.

Item 13. ON BOTH FORMS: Enter the phone number of your company contact.

NOTE: You may provide additional information that does not fit on this form in a signed letter that accompanies this your response. For example,

you may wish to report that your product has already been transferred to another company or that you have already voluntarily cancelled

this product. For these cases, please supply all relevant details so that the Agency can ensure that its records are correct.

4.EPA Batching of End-Use Products for Meeting Data Requirements for Reregistration
304

EPA'S BATCHING OF ALACHLOR PRODUCTS FOR MEETING ACUTE

MAMMALIAN TOXICITY DATA REQUIREMENTS FOR REREGISTRATION

In an effort to reduce the time, resources and number of animals needed to fulfill the

acute toxicity data requirements for reregistration of products containing Alachlor as

the active ingredient, the Agency has batched products which can be considered similar

for purposes of acute toxicity. Factors considered in the sorting process include each

product's active and inert ingredients (identity, percent composition and biological

activity), type of formulation (e.g., emulsifiable concentrate, aerosol, wettable powder,

granular, etc.), and labeling (e.g., signal word, use classification, precautionary labeling,

etc.). Note that the Agency is not describing batched products as "substantially similar"

since some products within a batch may not be considered chemically similar or have

identical use patterns.

Using available information, batching has been accomplished by the process described

in the preceding paragraph. Notwith-standing the batching process, the Agency

reserves the right to require, at any time, acute toxicity data for an individual product

should the need arise. 

Registrants of products within a batch may choose to cooperatively generate, submit

or cite a single battery of six acute toxicological studies to represent all the products

within that batch. It is the registrants' option to participate in the process with all other

registrants, only some of the other registrants, or only their own products within a

batch, or to generate all the required acute toxicological studies for each of their own

products. If a registrant chooses to generate the data for a batch, he/she must use one

of the products within the batch as the test material. If a registrant chooses to rely

upon previously submitted acute toxicity data, he/she may do so provided that the data

base is complete and valid by today's standards (see acceptance criteria attached), the

formulation tested is considered by EPA to be similar for acute toxicity, and the

formulation has not been significantly altered since submission and acceptance of the

acute toxicity data. Regardless of whether new data is generated or existing data is

referenced, registrants must clearly identify the test material by EPA Registration

Number. If more than one confidential statement of formula (CSF) exists for a product,

the registrant must indicate the formulation actually tested by identifying the

corresponding CSF.
305

In deciding how to meet the product specific data requirements, registrants must

follow the directions given in the Data Call-In Notice and its attachments appended to

the RED. The DCI Notice contains two response forms which are to be completed and

submitted to the Agency within 90 days of receipt. The first form, "Data Call-In

Response," asks whether the registrant will meet the data requirements for each

product. The second form, "Requirements Status and Registrant's Response," lists the

product specific data required for each product, including the standard six acute

toxicity tests. A registrant who wishes to participate in a batch must decide whether

he/she will provide the data or depend on someone else to do so. If a registrant

supplies the data to support a batch of products, he/she must select one of the

following options: Developing Data (Option 1), Submitting an Existing Study (Option

4), Upgrading an Existing Study (Option 5) or Citing an Existing Study (Option 6). If a

registrant depends on another's data, he/she must choose among: Cost Sharing (Option

2), Offers to Cost Share (Option 3) or Citing an Existing Study (Option 6). If a

registrant does not want to participate in a batch, the choices are Options 1, 4, 5 or 6.

However, a registrant should know that choosing not to participate in a batch does not

preclude other registrants in the batch from citing his/her studies and offering to cost

share (Option 3) those studies.

Twelve active products were found which contain Alachlor as the active ingredient. 

These products have been placed into the "no batch" category in accordance with the

active and inert ingredients, type of formulation and current labeling. 

The following product(s) may cite acute data as follows:

- EPA Reg. No. 524-344 may be supported by acute oral, acute dermal and/or acute

inhalation data generated with EPA Reg. Nos. 524-403 or 524-316.

No

Batch

EPA Reg. No. % Active Ingredient Formulation

Type

 241-311 Alachlor 34.5

Imazaquin 2.2

Liquid

241-329 Alachlor 32.4

Imazaquin 1.9

Liquid

524-296 15.0 Solid

524-314 45.1 Liquid
No

Batch

EPA Reg. No. % Active Ingredient Formulation

Type

306

524-315 60.0 Liquid

524-316 90.0 Liquid

524-329 Alachlor 27.2

Atrazine 15.5

Liquid

524-341 Alachlor 27.6

Glyphosate 14.8

Liquid

524-344 41.5 Microencap

Liquid

524-403 65.0 Microencap

Solid

524-418 Alachlor 25.2

Atrazine 14.3

Related atrazine

compounds 0.8

Microencap

Liquid

524-422 Alachlor 31.7

Trifluralin 3.9

Liquid
307

5.List of All Registrants Sent This Data Call-In (insert) Notice

This page has been replaced with an electronically generated list.

This page has been inserted as a place marker and is replaced by an electronically

generated PDCI List of Registrants page number 1 in the actual Printed version of the

Red document
308

e.List of Available Related Documents and Electronically Available Forms.

Pesticide Registration Forms are available at the following EPA

internet site:

http://www.epa.gov/opprd001/forms/.

Pesticide Registration Forms (These forms are in PDF format and require the Acrobat

reader) 

Instructions

 1. Print out and complete the forms. (Note: Form numbers that are bolded can

be filled out on your computer then printed.)

 2. The completed form(s) should be submitted in hardcopy in accord with the

existing policy. 

 3. Mail the forms, along with any additional documents necessary to comply

with EPA regulations covering your request, to the address below for the

Document Processing Desk.

 DO NOT fax or e-mail any form containing 'Confidential Business

Information' or 'Sensitive Information.'

 If you have any problems accessing these forms, please contact Nicole Williams at

(703) 308-5551 or by e-mail at williams.nicole@epamail.epa.gov.

The following Agency Pesticide Registration Forms are currently available via the

internet:

at the following locations:

8570-1 Application for Pesticide

Registration/Amendment

http://www.epa.gov/opprd001/forms/8570-1.pdf.

8570-4 Confidential Statement of Formula http://www.epa.gov/opprd001/forms/8570-4.pdf.

8570-5 Notice of Supplemental Registration

of Distribution of a Registered

Pesticide Product 

http://www.epa.gov/opprd001/forms/8570-5.pdf.

8570-17 Application for an Experimental Use

Permit

http://www.epa.gov/opprd001/forms/8570-17.pdf.

8570-25 Application for/Notification of State

Registration of a Pesticide To Meet a

Special Local Need 

http://www.epa.gov/opprd001/forms/8570-25.pdf.

8570-27 Formulator's Exemption Statement http://www.epa.gov/opprd001/forms/8570-27.pdf.
309

8570-28 Certification of Compliance with

Data Gap Procedures 

http://www.epa.gov/opprd001/forms/8570-28.pdf.

8570-30 Pesticide Registration Maintenance

Fee Filing 

http://www.epa.gov/opprd001/forms/8570-30.pdf.

8570-32 Certification of Attempt to Enter

into an Agreement with other

Restraints for Development of Data 

http://www.epa.gov/opprd001/forms/8570-32.pdf.

8570-34 Certification with Respect to

Citations of Data (in PR Notice

98-5)

http://www.epa.gov/opppmsd1/PR_Notices/pr98-5.pdf.

8570-35 Data Matrix (in PR Notice 98-5) http://www.epa.gov/opppmsd1/PR_Notices/pr98-5.pdf.

8570-36 Summary of the Physical/Chemical

Properties (in PR Notice 98-1)

http://www.epa.gov/opppmsd1/PR_Notices/pr98-1.pdf.

8570-37 Self-Certification Statement for the

Physical/Chemical Properties (in PR

Notice 98-1)

http://www.epa.gov/opppmsd1/PR_Notices/pr98-1.pdf.
310

Pesticide Registration Kit www.epa.gov/pesticides/registrationkit/.

 Dear Registrant:

 For your convenience, we have assembled an online registration kit which

contains the following pertinent forms and information needed to register a

pesticide product with the U.S. Environmental Protection Agency's Office of

Pesticide Programs (OPP):

 1. The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the

Federal Food, Drug and Cosmetic Act (FFDCA) as Amended by the Food

Quality Protection Act (FQPA) of 1996. 

 2. Pesticide Registration (PR) Notices 

 a. 83-3 Label Improvement Program--Storage and Disposal

Statements 

 b. 84-1 Clarification of Label Improvement Program 

 c. 86-5 Standard Format for Data Submitted under FIFRA 

 d. 87-1 Label Improvement Program for Pesticides Applied through

Irrigation Systems (Chemigation) 

 e. 87-6 Inert Ingredients in Pesticide Products Policy

Statement 

 f. 90-1 Inert Ingredients in Pesticide Products; Revised Policy

Statement 

 g. 95-2 Notifications, Non-notifications, and Minor Formulation

Amendments 

 h. 98-1 Self Certification of Product Chemistry Data with

Attachments (This document is in PDF format and requires the

Acrobat reader.) 

Other PR Notices can be found at http://www.epa.gov/opppmsd1/PR_Notices.

 3. Pesticide Product Registration Application Forms (These forms are in

PDF format and will require the Acrobat reader.) 

 a. EPA Form No. 8570-1, Application for Pesticide

Registration/Amendment 

 b. EPA Form No. 8570-4, Confidential Statement of Formula 

 c. EPA Form No. 8570-27, Formulator's Exemption

Statement 

 d. EPA Form No. 8570-34, Certification with Respect to Citations of

Data 

 e. EPA Form No. 8570-35, Data Matrix 
311

 4. General Pesticide Information (Some of these forms are in PDF format

and will require the Acrobat reader.) 

 a. Registration Division Personnel Contact List

 Biopesticides and Pollution Prevention Division (BPPD) Contacts

 Antimicrobials Division Organizational Structure/Contact List 

 b. 53 F.R. 15952, Pesticide Registration Procedures; Pesticide Data

Requirements (PDF format)

 c. 40 CFR Part 156, Labeling Requirements for Pesticides and

Devices (PDF format) 

 d. 40 CFR Part 158, Data Requirements for Registration (PDF

format) 

 e. 50 F.R. 48833, Disclosure of Reviews of Pesticide Data

(November 27, 1985) 

 Before submitting your application for registration, you may wish to consult 

some additional sources of information.

 These include: 

 1. The Office of Pesticide Programs' Web Site 

 2. The booklet "General Information on Applying for Registration of

Pesticides in the United States", PB92-221811, available through the

National Technical Information Service (NTIS) at the following address: 

 National Technical Information Service (NTIS)

 5285 Port Royal Road

 Springfield, VA 22161 

 The telephone number for NTIS is (703) 605-6000. Please note that EPA is

currently in the process of updating this booklet to reflect the changes in the

registration program resulting from the passage of the FQPA and the 

reorganization of the Office of Pesticide Programs. We anticipate that this

publication will become available during the Fall of 1998. 

 3. The National Pesticide Information Retrieval System (NPIRS) of Purdue

University's Center for Environmental and Regulatory Information

Systems. This service does charge a fee for subscriptions and custom

searches. You can contact NPIRS by telephone at (765) 494-6614 or

through their Web site. 

 4. The National Pesticide Telecommunications Network (NPTN) can

provide information on active ingredients, uses, toxicology, and chemistry

of pesticides. You can contact NPTN by telephone at 1-800-858-7378 or

through their Web site at ace.orst.edu/info/nptn/. 
312

 The Agency will return a notice of receipt of an application for registration or

amended registration, experimental use permit, or amendment to a petition if the

applicant or petitioner encloses with his submission a stamped, self-addressed

postcard. The postcard must contain the following entries to be completed by OPP: 

 Date of receipt 

 EPA identifying number 

 the Product Manager assignment 

 Other identifying information may be included by the applicant to link the

acknowledgment of receipt to the specific application submitted. EPA will stamp

the date of receipt and provide the EPA identifying File Symbol or petition number

for the new submission. The identifying number should be used whenever you

contact the Agency concerning an application for registration, experimental use

permit, or tolerance petition.

 To assist us in ensuring that all data you have submitted for the chemical are

properly coded and assigned to your company, please include a list of all synonyms,

common and trade names, company experimental codes, and other names which

identify the chemical (including "blind" codes used when a sample was submitted

for testing by commercial or academic facilities). Please provide a CAS number if

one has been assigned.
313

List of Available Related Documents

The following is a list of available documents for Dicofol that may further assist

you in responding to this Reregistration Eligibility Decision document. These

documents may be obtained by the following methods:

Electronic

File format: Portable Document Format (.PDF) Requires Adobe® Acrobat or

compatible reader. Electronic copies are available on our website

at www.epa.gov/REDs, or contact Kathryn Boyle at (703) 305-

6304.

1. PR Notice 86-5.

2. PR Notice 91-2 (pertains to the Label Ingredient Statement).

3. A full copy of this RED document.

4. A copy of the fact sheet for Alachlor

The following documents are part of the Administrative Record for Alachlor and

may included in the EPA's Office of Pesticide Programs Public Docket. Copies of

these documents are not available electronically, but may be obtained by contacting

the person listed on the Chemical Status Sheet.

1. Health and Environmental Effects Science Chapters.

2. Detailed Label Usage Information System (LUIS) Report.

The following Agency reference documents are not available electronically, but

may be obtained by contacting the person listed on the Chemical Status Sheet of

this RED document.

1. The Label Review Manual.

2. EPA Acceptance Criteria