United States Prevention, Pesticides EPA 738-R-05-002

Environmental Protection and Toxic Substances June 2005

 Agency (7508C)

Reregistration

Eligibility Decision for

2,4-D
Reregistration Eligibility Decision

for

2,4-D

List A

Case 0073

Approved By:

 ______________________

Debra Edwards, Ph.D.

Director, Special Review and

Reregistration Division

______________________

Date
iii

Table of Contents

Glossary of Terms and Abbreviations

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

2,4-D Reregistration Eligibility Decision Team ....................................... x

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

I. Introduction .................................................................1

II. Chemical Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

A. Regulatory History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

B. Chemical Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

C. Use Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

D. Estimated Usage of Pesticide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

III. Summary of 2,4-D Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

A. Human Health Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1. Toxicity of 2,4-D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

a. Toxicity Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

b. Safety and Database Uncertainty Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

c. Carcinogenicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

d. Cumulative Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

e. Endocrine Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2. Dietary Exposure and Risk from Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

a. Exposure Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

b. Population Adjusted Dose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

c. Food Risk Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

3. Dietary Exposure and Risk from Drinking Water . . . . . . . . . . . . . . . . . . . . . . . . . 24

a. Surface Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

b. Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

c. EDWCs Selected for Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4. Residential and Other Non-occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . 27

a. Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

b. Residential Handler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

1) Exposure Scenarios, Data, and Assumptions . . . . . . . . . . . . . . . . . . . . . . . . 29

2) Residential Handler Risk Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

c. Residential Postapplication Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

1) Exposure Scenarios, Data, and Assumptions . . . . . . . . . . . . . . . . . . . . . . . . 32

2) Postapplication Risk Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

d. Recreational Swimmer Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
iv

1) Exposure Scenarios, Data, and Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 35

2) Recreational Swimmer Risk Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

5. Aggregate Exposure and Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

a. Acute Aggregate Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

b. Chronic Aggregate Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

c. Short-term Aggregate Risk Assessments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

d. Cancer Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

e. Aggregate Risk Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

6. Occupational Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

a. Occupational Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

b. Occupational Handler Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

c. Occupational Handler Risk Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

d. Occupational Postapplication Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

1) Exposure Scenarios, Data, and Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 50

2) Occupational Postapplication Risk Estimates . . . . . . . . . . . . . . . . . . . . . . . . . 51

7. Human Incident Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

8. Cancer Epidemiology Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

B. Environmental Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

1. Environmental Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

a. Environmental Fate and Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

b. Aquatic Organism Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

1) Exposure to 2,4-D Acid in Surface Water . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

2) Surface Water Modeling of 2,4-D Esters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

3) Modeling of Direct Application of 2,4-D for Control of Aquatic Weeds . . . . 56

4) Modeling of 2,4-D Use on Rice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

c. Terrestrial Organism Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

1) Birds and Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

a) Exposure to Nongranular (Liquid) Formulations . . . . . . . . . . . . . . . . . . . . . . 58

b) Exposure to Granular Formulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

2) Non-target Terrestrial Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

2. Environmental Effects (Toxicity) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

a. Toxicity to Aquatic Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

b. Toxicity to Terrestrial Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

3. Ecological Risk Estimation (RQs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

a. Risk to Aquatic Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

1) Fish and Aquatic Invertebrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

2) Aquatic Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

b. Risk to Non-target Terrestrial Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

1) Birds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

2) Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

3) Non-Target Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

4) Non-target Terrestrial Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

4. Ecological Incidents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

5. Endangered Species Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
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6. Risk Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

a. Characterization of risk to aquatic organisms from direct aquatic application . . 74

b. Characterization of risk to mammals from terrestrial use . . . . . . . . . . . . . . . . . 75

c. Characterization of risk to birds from terrestrial use . . . . . . . . . . . . . . . . . . . . . 76

d. Characterization of risk to non-target plants from terrestrial use . . . . . . . . . . . . 77

IV. Risk Management, Reregistration, and Tolerance Reassessment Decision . . . . . . . . . . . . . . . 79

A. Determination of Reregistration Eligibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

B. Public Comments and Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

C. Regulatory Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

1. Food Quality Protection Act Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

a. “Risk Cup” Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

b. Determination of Safety to U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

2. Endocrine Disruptor Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

3. Cumulative Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

4. Special Review Disposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

5. Dioxin Contaminants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

D. Tolerance Reassessment Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

1. Tolerances Currently Listed Under 40 CFR §180.142 . . . . . . . . . . . . . . . . . . . . . . 84

2. Tolerances to Be Proposed Under 40 CFR §180.142 . . . . . . . . . . . . . . . . . . . . . . . 89

3. Codex Harmonization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

4. Residue Analytical Methods - Plants and Livestock (GLN 860.1340) . . . . . . . . . . . 97

E. Regulatory Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

1. Human Health Risk Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

a. Residential Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

1) Residential risk summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

2) Residential Post-application Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

3) Residential Swimmer Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

b. Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

1) Aggregate Risk Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

2) Acute Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

3) Short-term Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

4) Chronic (Non-Cancer) Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

5) Aggregate Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

c. Occupational Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

1) Handler Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

2) Post-application Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

2. Environmental Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

a. Birds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

b. Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

c. Aquatic Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

d. Non-target Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

e. Non-target Terrestrial Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

f. Summary of Environmental Risk Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . 106
vi

F. Other Labeling Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

1. Endangered Species Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

2. Spray Drift Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

3. Consumer Labeling Initiative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

V. What Registrants Need To Do . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

A. Manufacturing Use Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

1. Additional Generic Data Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

B. End-Use Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

1. Additional Product-Specific Data Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . 111

2. Labeling for End-Use Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

C. Existing Stocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

D. Required Labeling Changes Summary Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

VI. Appendicies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

Appendix A. Table of 2,4-D Use Patterns Eligible for Reregistration (Case 0073) . . . . . . . 154

Appendix B. Data Supporting Guideline Requirements for the Reregistration of 2,4-D . . . 169

Appendix C. Technical Support Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184

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

Eligibility Decision (Bibliography) for 2,4-D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

Appendix E. Generic Data Call-In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292

Appendix F. Product Specific Data Call-In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294

Appendix G. EPA’s Batching of 2,4-D Products for Meeting Acute Toxicity Data

Requirements for Reregistration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296

Appendix H. List of Registrants Sent This Data Call-In . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
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Glossary of Terms and Abbreviations

A Acre

AGDCI Agricultural Data Call-In

ae Acid Equivalent

ai Active Ingredient

aPAD Acute Population Adjusted Dose

AR Anticipated Residue

BCF Bioconcentration Factor

CFR Code of Federal Regulations

cPAD Chronic Population Adjusted Dose

CSF Confidential Statement of Formula

CSFII USDA Continuing Surveys for Food Intake by Individuals

DCI Data Call-In

DEEM Dietary Exposure Evaluation Model

DFR Dislodgeable Foliar Residue

DWLOC Drinking Water Level of Comparison.

EC Emulsifiable Concentrate Formulation

EDSP Endocrine Disruption Screening Program

EDWC Estimated Drinking Water Concentration

EEC Estimated Environmental Concentration

EPA Environmental Protection Agency

EUP End-Use Product

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

G Granular Formulation

GENEEC Tier I Surface Water Computer Model

GLN Guideline Number

HAFT Highest Average Field Trial

HAT Hour After Treatment

IR Index Reservoir

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.

LOC Level of Concern

LOD Limit of Detection

LOAEL Lowest Observed Adverse Effect Level
viii

MATC Maximum Acceptable Toxicant Concentration

:g/g Micrograms Per Gram

:g/L Micrograms Per Liter

mg/kg/day Milligram Per Kilogram Per Day

mg/L Milligrams Per Liter

MOE Margin of Exposure

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

studies submitted

MSWC Maximum Swimming Water Concentration

MUP Manufacturing-Use Product

NA Not Applicable

NAWQA USGS National Water Quality Assessment

NCOD National Drinking Water Contaminant Occurrence Database

NPDES National Pollutant Discharge Elimination System

NR Not Required

NOAEL No Observed Adverse Effect Level

OP Organophosphate

OPP EPA Office of Pesticide Programs

OPPTS EPA Office of Prevention, Pesticides and Toxic Substances

ORETF Outdoor Residential Exposure Task Force

PAD Population Adjusted Dose

PCA Percent Crop Area

PDIC Product-Specific Data Call-In

PDP USDA Pesticide Data Program

PHED Pesticide Handler's Exposure Data

PHI Preharvest Interval

ppb Parts Per Billion

PPE Personal Protective Equipment

ppm Parts Per Million

PRZM/

EXAMS Tier II Surface Water Computer Model

Q1* The Carcinogenic Potential of a Compound, Quantified by the EPA's Cancer Risk

Model

RAC Raw Agriculture Commodity

RED Reregistration Eligibility Decision

REI Restricted Entry Interval

RfD Reference Dose

RQ Risk Quotient

SCI-GROW Tier I Ground Water Computer Model

SAP Science Advisory Panel

SF Safety Factor

SLC Single Layer Clothing

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

STORET Storage and Retrieval Environmental Data System
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TGAI Technical Grade Active Ingredient

TRR Total Radioactive Residue

TWAM Time Weighted Annual Mean

USDA United States Department of Agriculture

USGS United States Geological Survey

UF Uncertainty Factor

UV Ultraviolet

WPS Worker Protection Standard
x

2,4-D Reregistration Eligibility Decision Team

Office of Pesticide Programs:

Biological and Economic Analysis Assessment

Elisa Rim

Rafael Prieto

Steve Jarboe

Tim Kiely

Environmental Fate and Effects Risk Assessment

Mark Corbin

Bill Evans

James Hetrick

Sid Abel

Health Effects Risk Assessment

Bill Hazel

Timothy Dole

Linda Taylor

Felecia Fort

Toiya Jimerson

Michael Metzger

Whang Phang

Risk Management

Katie Hall

Mark Seaton

Moana Appleyard

Tom Myers

Margaret Rice
xi

Executive Summary

EPA has completed its review of public comments on the preliminary risk assessments and is

issuing its risk management decision for 2,4-D. The revised risk assessments are based on review of

the required target data base supporting the use patterns of the currently registered products and

additional information received from the 2,4-D Task Force II. After considering the risks identified

in the revised risk assessment and comments and mitigation suggestions from interested parties, EPA

developed its risk management decision for uses of 2,4-D that pose risks of concern. The decision is

discussed fully in this document.

2,4-D is an herbicide in the phenoxy or phenoxyacetic acid family that is used post-emergence

for selective control of broadleaf weeds. 2,4-D is registered for use on a variety of food/feed sites

including field, fruit, and vegetable crops. 2,4-D is also registered for use on turf, lawns, rights-ofway, aquatic and forestry applications. Residential homeowners may use 2,4-D on lawns.

Based primarily on pesticide usage information from 1992 through 2000 for agriculture and

1993 through 1999 for non-agriculture, total annual domestic usage of 2,4-D is approximately 46

million pounds, with 30 million pounds (66%) used for agriculture and 16 million pounds (34%) used

for non-agriculture. In terms of pounds, total 2,4-D usage is allocated mainly to pasture/rangeland

(24%), lawn by homeowners with fertilizer (12%), spring wheat (8%), winter wheat (7%),

lawn/garden by lawn care operators/landscape maintenance contractors (7%), lawn by homeowners

alone (without fertilizer) (6%), field corn (6%), soybeans (4%), summer fallow (3%), hay other than

alfalfa (3%) and roadways (3%). Agricultural sites with at least 10% of U.S. acreage treated include

spring wheat (51%), filberts (49%), sugarcane (36%), barley (36%), seed crops (29%), apples (20%),

rye (16%), winter wheat (15%), cherries (15%), oats (15%), millet (15%), rice (13%), soybeans

(12%), and pears (10%). For 2,4-D, rates per application and rates per year are generally less than

1.50 pounds acid equivalent (a.e.) per acre and 2.00 pounds a.e. per acre (lbs ae/A), respectively. 2,4-

D is used predominantly in the Midwest, Great Plains, and Northwestern United States.

The Food Quality Protection Act (FQPA) 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.” Unlike other pesticides for which EPA has followed a cumulative risk

approach based on a common mechanism of toxicity, EPA has not made a common mechanism of

toxicity finding as to 2,4-D and any other substances. For the purposes of this tolerance action,

therefore, EPA has not assumed that 2,4-D has a common mechanism of toxicity with other

substances. For information regarding EPA’s efforts to determine which chemicals have a common

mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see the policy

statements released by EPA’s Office of Pesticide Programs (OPP) concerning common mechanism

determinations and procedures for cumulating effects from substances found to have a common

mechanism on EPA’s website at http://www.epa.gov/pesticides/cumulative/.

Dietary Risk
xii

Acute and chronic dietary exposures for food and drinking water do not exceed the Agency’s

level of concern; therefore, no mitigation is warranted at this time for any dietary exposure to 2,4-D.

The maximum contaminant level (MCL) established by EPA’s Office of Water (OW) for 2,4-D

is 70 micrograms/liter (ug/l; ppb). Further, it is important to note that an MCL is an enforceable limit

under the Safe Drinking Water Act (SDWA). To minimize the possibility that aquatic applications

will result in drinking water concentrations in excess of the MCL, registrants and the Agency have

developed label language for the direct aquatic use of 2,4-D to control aquatic weeds. 

Residential Risk

Potential exposures are anticipated as a result of homeowner and commercial applications in

residential areas. Applications can be made to lawns. In addition to residential areas, there are also

potential postapplication exposure scenarios that may occur in public areas such as parks, recreational

areas, and golf courses. The Agency evaluated 2,4-D exposures to residential handlers during

mixing, loading and application to turf/ornamentals and 2,4-D postapplication exposure to residues by

adults and children on treated turf. 

In preliminary versions of the risk assessment, when considered alone, acute and short-term

residential risks posed by the use of 2,4-D were not of concern to the Agency; however, when

considered as part of an aggregate exposure with food and drinking water, exposures did exceed the

Agency’s level of concern. As a result, 2,4-D registrants agreed to reduce the maximum application

rate to turf and residential lawns from 2.0 lbs ae/A to 1.5 lbs ae/A. Chronic residential exposures to

2,4-D are not expected due to its use pattern.

Aggregate Risk

An aggregate risk assessment looks at the combined risk from dietary exposure (food and

drinking water pathways), as well as exposures from non-occupational sources (e.g., residential uses). 

In the preliminary and revised risk assessments, the estimated acute and short-term exposures

exceeded the Agency’s level of concern. As a result, 2,4-D registrants agreed to reduce the maximum

application rate to turf and residential lawns from 2.0 pounds acid equivalent per acre (lbs ae/A) to

1.5 lbs ae/A. The current risk assessment considers exposures from the reduced application rate for

residential turf. 

Two methods of aggregate risk calculations were employed in assessing the aggregate risk of

2,4-D. The first method is the drinking water level of concern (DWLOC) method. OPP (Office of

Pesticide Programs) has traditionally compared estimates of concentrations of a pesticide in drinking

water to DWLOCs. A DWLOC is the portion of the acute population adjusted dose (aPAD) or

chronic population adjusted dose (cPAD) remaining after estimated dietary (food only) exposures

have been subtracted and the remaining exposure has been converted to a concentration (ug/liter or

ppb). This concentration value (DWLOC) represents the available or allowable exposure through

drinking water. The second method is the forward calculation method. In this approach, food,

drinking water, and residential exposures are aggregated and compared to an appropriate endpoint. A
xiii

population adjusted dose, or PAD, is the reference dose (RfD) adjusted for the FQPA safety factor. A

risk estimate that is less than 100% of the acute PAD (aPAD), the dose at which an individual could

be exposed over the course of a single day and no adverse health effects would be expected, does not

exceed EPA’s level of concern. Likewise, risk estimate that is less than 100% of the chronic PAD

(cPAD), the dose at which an individual could be exposed over the course of a lifetime and no

adverse health effects would be expected, does not exceed EPA’s level of concern.

In the case of 2,4-D, the DWLOCs were calculated for comparison to the MCL established by

the EPA Office of Water and aggregate risks were calculated using the forward calculation approach

for comparison to the appropriate endpoint. The respective DWLOCs and aggregate risks are shown

for acute, chronic and short term exposures in the following sections.

Acute aggregate risk. The acute aggregate risk assessments address exposure to 2,4-D

residues in food and water using both the DWLOC and forward calculation approach. Acute

residential exposures from swimming in treated water bodies or playing on treated turf were not

included because exposures are unlikely to co-occur with acute dietary exposures. The acute

DWLOCs are 432 ppb or greater with the most sensitive population being females 13-49 years old. 

The estimated drinking water concentrations (EDWCs) of 118 ug/liter for surface water and 15

ug/liter for groundwater are substantially less than the DWLOCs which means that the risks are not of

concern. 

Acute aggregate risks were also assessed by aggregating acute food exposures and acute water

exposures using Lifeline. The acute aggregate risks are not of concern because they are less than 100

percent of the aPAD. The highest risks (58 percent of the aPAD) are for females 13-49 years old

because these risks are based upon the lower no-observed adverse effect level (NOAEL) of 25

mg/kg/day from a developmental study in rats.

 

Short-term aggregate risk. Short term aggregate risk assessments were conducted by

calculating DWLOCs based upon short term turf exposures, chronic food exposures and short term

endpoints. Short term exposures from swimming in treated water bodies were not included because

these exposures represent high-end unlikely scenarios. The short term DWLOCs were calculated

only for females 13-49 and children 1-6 because these population subgroups have the highest

exposure and are protective of the other subgroups. The DWLOCS range from 24 to 54 ug/liter. 

These DWLOCs are all greater than the EDWCs, which range from 15 to 23 ug/liter, and indicate that

short term risks are not of concern.

Short term aggregate risks were also assessed by aggregating short term turf exposures, chronic

food exposures and chronic water exposures using the forward calculation approach. Short term

aggregate risks were calculated only for females 13-49 and children 1-6 because these population

subgroups have the highest exposure and are protective of the other subgroups. The short term

aggregate margins of exposure (MOEs) indicate that the short term risks are not of concern because

the MOEs equal or exceed the target MOE of 1000.
xiv

Chronic (non-cancer) aggregate risk. Chronic DWLOCs were calculated based upon chronic

dietary exposures. As there are no chronic residential exposures, residential exposures were not

included in the chronic DWLOC calculations. The chronic DWLOCs are 47 ug/liter or greater with

the most sensitive populations being infants and children. The EDWCs, which range from 1.5 to 23

ug/liter, are less than the DWLOCs which means that the risks are not of concern. It should be noted

that the master label indicates that potable water consumption from a treated water body cannot begin

until the 2,4-D concentration is 70 ug/liter or below, therefore an annual average exposure at the

MCL of 70 ug/liter would not occur because dissipation would reduce the initial concentration of 70

ug/liter to an annual average concentration of 11 ug/liter.

Chronic aggregate risks were also assessed by aggregating chronic food exposures and chronic

water exposures using the forward calculation approach. The chronic aggregate risks are presented as

percent cPAD are not of concern because they are less than 100 percent of the cPAD. The highest

risks (38 percent of the cPAD) are for children 1-2 years old.

Occupational Risk

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

exposed to 2,4-D during and after normal use. The Agency identified 18 handler scenarios resulting

from mixing/loading and applying 2,4-D for crop and non-crop uses. For the occupational use of 2,4-

D, EPA is concerned about any Margin of Exposure (MOE) less than 100, which incorporates

uncertainty factors of 10x for interspecies variation and 10x for intraspecies variation. 

With the exception of mixing/loading wettable powder, all of the short-term and intermediateterm MOEs exceed the target of 100 with baseline personal protective equipment (PPE) (i.e., longsleeved shirt, long pants, shoes plus socks, no respirator) or single layer PPE (i.e., long-sleeved shirt,

long pants, shoes plus socks, gloves, no respirator) and are not of concern. The MOEs for handling

wettable powder are above 100 with engineering controls (i.e., water soluble bags).

Ecological Risk

Fish and Aquatic Invertebrates: Estimated risk quotients (RQs) from use of 2,4-D acid and

amine salts in aquatic weed control through direct subsurface application to water bodies exceed the

restricted use LOCs for freshwater invertebrates. There are no chronic LOC exceedances for this use. 

Estimated RQs from use of 2,4-D BEE in weed control through direct subsurface application to water

bodies exceed the acute risk level of concern (LOC) for freshwater fish and invertebrates and chronic

risk LOC for freshwater and estuarine fish and freshwater invertebrates when compared on an acid

equivalent basis. Estimated RQs from use of 2,4-D acid and amine salts in rice paddies exceed the

acute endangered species LOCs for freshwater invertebrates.

Non-Target Aquatic Plants: For non-target aquatic plants, estimated RQs from the runoff/drift

of 2,4-D acid and amine salts from use on terrestrial crops exceed the aquatic vascular plant

endangered species LOCs for use of 2,4-D acid and amine salts on pasture and apples. Consideration

of average application rates and assuming a proportional reduction in EECs results in RQs below the
xv

endangered species LOC. Likewise, there are no LOC exceedances from the drift of the ester forms

to aquatic water bodies or from the runoff of the ester forms to water bodies from use on terrestrial

sites. 

Estimated RQs for the scenario of direct application to water for aquatic weed control for 2,4-D

acid and amine salts exceed the acute and endangered species LOCs for aquatic vascular and acute

the LOC for non-vascular plants, while estimated RQs from use of 2,4-D BEE (the only ester

registered for aquatic weed control) for direct application to water for weed control exceed all LOCs

for vascular and the acute LOC for non-vascular plants.

Estimated RQs for use of 2,4-D acid and amine salts in rice paddies exceed the acute and

endangered species LOCs for aquatic vascular plants. Consideration of average application rates

results in RQs below the endangered species LOCs.

Birds: For non-granular spray applications of 2,4-D acid, amine salts, and esters, estimated RQs

exceed acute LOCs for most crop scenarios for short grass, tall grass, and broadleaf forage exposures. 

For birds that eat fruit and large insects, acute endangered LOCs are exceeded for non-cropland,

forest, and cranberry scenarios. Chronic LOCs are exceeded for birds that forage on short grass when

the application rate of 2,4-D ranges from 2.0 to 4.0 lbs ae/A such as with non-cropland areas,

cranberries, or asparagus. For granular broadcast applications, acute LOCs are exceeded for several

different crop scenarios and bird weights. The chronic LOC is not exceeded for granular broadcast

applications. 

Mammals: For non-granular formulations of 2,4-D, estimated RQs exceed acute LOCs for

mammals feeding on plants and insects for all uses assessed for small and medium size mammals,

except potatoes and citrus. There were no exceedances for granivores exposed to non-granular

formulations of 2,4-D. LOCs for acute exposure to granular 2,4-D products are exceeded for all sites

with the following exceptions: 1000 g mammals in turf, aquatic areas, and cranberries. Mammalian

chronic RQs range from 0.05 to 200 and chronic LOCs were exceeded in all cases with the exception

of potatoes and citrus (large insects, seeds). Consideration of average application rates results in

acute RQs below the LOCs for non-granular and granular applications. However, consideration of

average application rates for non-granular and granular applications did not result in RQs below the

chronic LOC. 

Insects: Since study results show that 2,4-D DMAS and 2,4-D EHE are practically non-toxic to

honey bees, the potential for 2,4-D and its salts and esters is predicted to pose minimal risk to

pollinators and other beneficial insects. 

Non-Target Terrestrial Plants: Estimated RQs exceed acute LOCs for both non-endangered

and endangered plants for non-granular and granular uses at many use sites. Consideration of average

application rates did not result in RQs below LOCs. 

In summary, some ecological risks are of concern on some sites for some species. The

Agency’s characterization of its assessment of ecological risk is provided in section III.B.3 of this

document. The mitigation measures of (1) reducing maximum application rates, and (2) specifying a
xvi

required spray droplet size of “Medium to Coarse” or coarser (i.e., prohibiting “fine” sprays) are

expected to lessen, but not eliminate, the risk of 2,4-D to wildlife and plants.

Summary of Mitigation Measures

EPA has determined that 2,4-D is eligible for reregistration provided the mitigation outlined in

this document is implemented. 

Dietary Risk

• Acute and chronic dietary exposures for food and drinking water do not exceed the Agency’s

level of concern; therefore, no mitigation is warranted at this time for any dietary exposure to

2,4-D.

Residential Risk

C Maximum turf rate is reduced from 2.0 lbs ae/A to 1.5 lbs ae/A.

C At the agreed-upon maximum application rate of 1.5 lbs ae/A for residential turf, acute and

short-term residential risks posed by the use of 2,4-D are not of concern to the Agency. Due to

its use pattern, chronic residential exposures to 2,4-D are not expected.

Occupational Risk

• Risks from handling wettable-powder products will be mitigated by requiring wettable powder

products to be packaged in water-soluble packaging.

• Personal protective equipment (PPE) prescribed in the exposure reduction plan set forth in 1992

will be replaced with the PPE requirements outlined in this document. 

Ecological Risk

• The measures to control spray drift are expected to reduce the risk of 2,4-D to non-target plants.

• Maximum turf rate is reduced from 2.0 lbs ae/A to 1.5 lbs ae/A.

• Implementation of the application rates set forth in the Master Label will reduce rates (as

compared to current rates on existing labels) for field corn, popcorn, sweet corn, small grains,

fallowland/stubble, non-cropland, turf, aquatic applications (surface), pasture, and soybean. 
Page 1 of 304

I. Introduction

The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was amended in 1988 to

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

The amended Act calls for the development and submission of data to support the reregistration of an

active ingredient, as well as a review of all submitted data by the U.S. Environmental Protection

Agency (referred to as EPA or "the Agency"). Reregistration involves a thorough review of the

scientific database 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 or not the

pesticide meets the "no unreasonable adverse effects" criteria of FIFRA. 

On August 3, 1996, the Food Quality Protection Act of 1996 (FQPA) was signed into law. This

Act amends FIFRA and the Federal Food Drug and Cosmetic Act (FFDCA) to require reassessment

of all existing tolerances for pesticides in food. FQPA also requires EPA to review all tolerances in

effect on August 3, 1996 by August 3, 2006. In reassessing these tolerances, the Agency must

consider, among other things, aggregate risks from non-occupational sources of pesticide exposure,

whether there is increased susceptibility to infants and children, and the cumulative effects of

pesticides with a common mechanism of toxicity. When a safety finding has been made that

aggregate risks are not of concern and the Agency concludes that there is a reasonable certainty of no

harm from aggregate exposure, the tolerances are considered reassessed. EPA decided that, for those

chemicals that have tolerances and are undergoing reregistration, tolerance reassessment will be

accomplished through the reregistration process.

As mentioned above, FQPA requires EPA to consider "available information" concerning the

cumulative effects of a particular pesticide's residues and "other substances that have a common

mechanism of toxicity" when considering whether to establish, modify, or revoke a tolerance. 

Potential cumulative effects of chemicals with a common mechanism of toxicity are considered

because low-level exposures to multiple chemicals causing a common toxic effect by a common

mechanism could lead to the same adverse health effect as would a higher level of exposure to any

one of these individual chemicals. For information regarding EPA’s efforts to determine which

chemicals have a common mechanism of toxicity and to evaluate the cumulative effects of such

chemicals, see the policy statements released by the EPA’s Office of Pesticide Programs concerning

common mechanism determinations and procedures for cumulating effects from substances found to

have a common mechanism on EPA’s website at http://www.epa.gov/pesticides/cumulative/. 

Unlike other pesticides for which EPA has considered cumulative risk based on a common

mechanism of toxicity, EPA has not made a common mechanism of toxicity finding for 2,4-

dichlorophenoxyacetic acid (2,4-D). Therefore, for the purposes of tolerance reassessment and a

decision on reregistration eligibility, EPA is assuming that 2,4-D does not share a common

mechanism of toxicity with other compounds. In the future, if information suggests 2,4-D shares a

common mechanism of toxicity with other compounds, additional testing may be required and a

cumulative assessment may be necessary. 
Page 2 of 304

This document presents summaries of EPA’s revised human health and ecological risk

assessments, tolerance reregistration decision, and the reregistration eligibility decision for 2,4-D. 

The document consists of six sections. Section I contains the regulatory framework for

reregistration/tolerance reassessment. Section II provides a profile of the use and usage of the

chemical. Section III gives an overview of the revised human health and environmental effects risk

assessments based on data, public comments, and other information received in response to the

preliminary risk assessments. Section IV presents the Agency’s reregistration eligibility and risk

management decisions. Section V summarizes label changes necessary to implement the risk

mitigation measures outlined in Section IV. Finally, the Appendices list related information,

supporting documents. The preliminary and revised risk assessments for 2,4-D are available in the

Public Docket, under docket number OPP-2004-0167 and on the Agency’s web page,

http://www.epa.gov/edockets.
Page 3 of 304

II. Chemical Overview

A. Regulatory History

2,4-D has been used as an herbicide since the mid-1940s. Currently over 600 end-use products

are registered for use on over 300 distinct agricultural and residential sites, and there are over 100

tolerances for 2,4-D listed in the Code of Federal Regulations. 2,4-D was the subject of a

Registration Standard and a Registration Standard Guidance Document dated February 16, 1988 and

September 9, 1988, respectively. These documents summarized the regulatory conclusions based on

available data, and specified the additional data required for reregistration purposes. Numerous data

submissions have been received and evaluated since the Registration Standard Guidance Document

was published. 

Special Review

2,4-D has been in pre-Special Review status since September 22, 1986, because of

carcinogenicity concerns. More specifically, there were concerns for epidemiological links of 2,4-D

to non-Hodgkin’s lymphoma from both occupational and residential exposure. A proposed decision

not to initiate Special Review was published (53 FR 9590) on March 23, 1988 based on findings that

such a link could not be established. The final decision was deferred until reregistration. In part to

address these concerns, the 2,4-D Task Force agreed to risk reduction measures in September 1992

that included an exposure reduction plan effected through modifications of technical and

manufacturing-use product labels and implementation of a user education program. 

A Science Advisory Board/Scientific Advisory Panel Special Joint Committee reviewed

available epidemiological and other data on 2,4-D in 1992 and concluded that “the data are not

sufficient to conclude that there is a cause and effect relationship between exposure to 2,4-D and nonHodgkin’s lymphoma.” 2,4-D was classified as a Group D, not classifiable as to human

carcinogenicity. The Agency requested further histopathological examinations of rat brain tissues and

mouse spleen tissues in question. These exams were submitted and reviewed, and on March 16,

1999, the Agency notified the 2,4-D Task Force that the Agency would continue to classify 2,4-D as

a Group D carcinogen. 

The Agency has twice recently reviewed epidemiological studies linking cancer to 2,4-D. In

the first review, completed January 14, 2004, EPA concluded there is no additional evidence that

would implicate 2,4-D as a cause of cancer (EPA, 2004). The second review of available

epidemiological studies occurred in response to comments received during the Phase 3 Public

Comment Period for the 2,4-D RED. EPA’s report, dated December 8, 2004 and authored by EPA

Scientist Jerry Blondell, Ph.D., found that none of the more recent epidemiological studies

definitively linked human cancer cases to 2,4-D. 

Final notice of the Agency’s decision not to initiate Special Review will be issued at the

completion of the reregistration process.
Page 4 of 304

Residue Tolerances

Tolerances for residues of 2,4-D in/on plant and processed food/feed commodities, fish, and

potable water are expressed in terms of 2,4-D per se [40 CFR §180.142(a)(1-6 and 9-12) and (b)]. 

There are currently approximately 110 tolerances for 2,4-D. 

The Industry Task Force II on 2,4-D Research Data (Task Force II) is supporting the

reregistration of 2,4-D. The members of the Task Force currently include Agro-Gor Corp (jointly

owned by Atanor, S.A. and PBI-Gordon Corp.), Dow AgroSciences, and Nufarm USA. In addition,

USDA’s Interregional Project No. 4 (IR-4) is supporting the reregistration of a number of minor crop

uses for 2,4-D, and the California Citrus Quality Council (CCQC) is supporting selected uses of 2,4-

D isopropyl ester (IPE) on citrus fruits.

B. Chemical Identification

2,4-D [2,4-dichlorophenoxyacetic acid] is a List A pesticide active ingredient classified as an

herbicide, a plant growth regulator, and a fungicide. It is, however, mainly used as a selective

postemergence herbicide for the control of broadleaf weed species in a variety of food/feed sites

including field, fruit, and vegetable crops. In addition to the acid form, there are numerous salts and

esters of 2,4-D in Reregistration Case 0073, each with an assigned PC Code number, that are

presently registered as active ingredients in end-use products (EPs). Nine forms of 2,4-D are

currently supported; these forms are listed in Table 1 below. With regards to analytical methodology,

the quantitative recovery of residues of concern are enhanced by the formation of the more polar acid

form of 2,4-D. Given that results of 2,4-D analyses are typically expressed in terms of the quantified

levels of the acid form, 2,4-D concentrations in product formulations are typically referred to in terms

of acid equivalents (ae).

Chemical structures and information are presented in Tables 1 and 2 for 2,4-D acid and those

salts and esters with registered manufacturing-use and/or end-use products (MPs/EPs) being

supported by 2,4-D Task Force II and its member companies. 

Table 1. Chemical Structures for Supported Forms of 2,4-D Acid, Amine Salts, and Esters

2,4-D active ingredients with registered MPs/EPs

2,4-D acid

Empirical Formula: C8H6Cl2O3

Molecular Weight: 221.0

CAS Registry No.: 94-75-7

PC Code: 030001

2,4-D sodium salt (Na)

Empirical Formula: C8H5Cl2NaO3

Molecular Weight: 243.03

CAS Registry No.: 2702-72-9

PC Code: 030004
2,4-D active ingredients with registered MPs/EPs

Page 5 of 304

O

Cl

O

Cl

O

[NH2(CH3)2]

+

O

Cl Cl

O

O

NH+(CH2CHOHCH3)3

O

Cl Cl

OH

O

O

Cl Cl

O

O

Na+

O

Cl Cl

O

O-[NH2(CH2CH2OH)2]

+

Cl Cl

O

O

O

-

[NH3CH(CH3)2]

+

2,4-D diethanolamine salt (DEA)

Empirical Formula: C12H17Cl2NO5

Molecular Weight: 326.18

CAS Registry No.: 5742-19-8

PC Code: 030016

2,4-D dimethylamine salt (DMA)

Empirical Formula: C10H13Cl2NO3

Molecular Weight: 266.13

CAS Registry No.: 2008-39-1

PC Code: 030019

2,4-D isopropylamine salt (IPA)

Empirical Formula: C11H15Cl2NO3

Molecular Weight: 280.04

CAS Registry No.: 5742-17-6

PC Code: 030025

2,4-D triisopropanolamine salt (TIPA)

Empirical Formula: C17H27Cl2NO6

Molecular Weight: 412.31

CAS Registry No.: 32341-80-3

PC Code: 030035

2,4-D 2-butoxyethyl ester (BEE)

Empirical Formula: C14H18Cl2O4

Molecular Weight: 321.20

CAS Registry No.: 1929-73-3

PC Code: 030053

2,4-D 2-ethylhexyl ester (2-EHE) 1

Empirical Formula: C16H22Cl2O3

Molecular Weight: 333.27

CAS Registry No.: 1928-43-4

PC Code: 030063
2,4-D active ingredients with registered MPs/EPs

Page 6 of 304

O

Cl Cl

O

O

CH3

CH3 O

Cl Cl

O

O

O CH3

Cl Cl

O

O CH3

O CH3

2,4-D isopropyl ester (IPE)

Empirical Formula: C11H12Cl2O3

Molecular Weight: 263.12

CAS Registry No.: 94-11-1

PC Code: 030066

1

 Formerly identified as the isooctyl ester.

Available data concerning identification of the active ingredients are summarized in Table 2 for

2,4-D acid, salts, and esters with registered MPs/EPs.
Page 7 of 304

Table 2. Available Data Concerning Identification of the Active Ingredient 1

Active ingredient

(PC Code) Color Physical State

Melting Point/

Boiling Point

Density/Specific

Gravity

Octanol/Water

Partition Coeff. Vapor Pressure 

2,4-D acid

(030001) white crystalline solid m.p. 138-141 C s.g.=1.416 at 25 C

Log KO/W

0.001 M sol’n

pH 5 2.14

pH 7 0.177

pH 9 0.102

1.4 x 10-7 mm Hg

at 25 C

wa

2,4-D Na salt

(030004) white powder m.p. 200 C bulk = 42.2 lb/ft3 at 25 C N/A 2; salt dissociates to acid in water wa

C

2,4-D DEA salt

(030016) cream powder m.p. 83 C

bulk = 0.762

g/cm3

at 25 C

2.24 x 10-2

 at 25 C

<1.33 x 10-5 Pa at

25 C

mg

wa

2,4-D DMA salt

(030019) amber aqueous liquid m.p. 118-120 C (PAI) s.g. = 1.23 at 20 C N/A; salt dissociates to acid in water <1 x 10-7 mm Hg at 26 C g/

wa

2,4-D IPA salt

(030025) amber aqueous liquid m.p. 121 C (PAI) s.g. = 1.15 at 20 C N/A; salt dissociates to acid in water g/

wa

2,4-D TIPA salt

(030035) amber aqueous liquid m.p. 87-110 C (PAI) s.g. = 1.21 at 20 C N/A; salt dissociates to acid in water g/

wa

2,4-D BEE

(030053)

dark

amber liquid b.p. 89 C s.g. = 1.225 at 20 C log = 4.13-4.17 at 25 C 2.4 x 10-6 mm Hg at 25 C g/

wa

2,4-D 2-EHE

(030063)

dark

amber liquid b.p. 300 C s.g. = 1.152 at 20 C log = 5.78 (temp N/A) 3.6 x 10-6 mm Hg (temp N/A) wa

2,4-D IPE

(030066)

pale

amber liquid b.p. 240 C s.g. = 1.252 at 25 C 253.8 ± 44.4 (temp N/A) 5.3 x 10-6 mbar wa

1 Data assembled from Agency memoranda and comprehensive review documents, including the 2,4-D Reregistration Standard.2 N/A = Not available.
Page 8 of 304

C. Use Profile

2,4-D comes in multiple chemical forms and is found in numerous end-use products intended

for use in a wide range of use patterns. 2,4-D is an ingredient in approximately 660 agricultural and

home use products, as a sole active ingredient and in conjunction with other active ingredients. 2,4-D

is formulated primarily as an amine salt in an aqueous solution or as an ester in an emulsifiable

concentrate. Chemical forms covered by this risk assessment are as 2,4-D acid, 2,4-D DMAS, 2,4-D

IPA, 2,4-D TIPA, 2,4-D EHE, 2,4-D BEE, 2,4-D DEA, 2,4-D IPE, and 2,4-D sodium salt. Copies of

all labels may be found at http://www.cdpr.ca.gov/docs/epa/m2.htm. The following is information on

the currently registered uses including an overview of use sites and application methods. A detailed

table of the uses of 2,4-D eligible for reregistration is contained in Appendix A.

Type of Pesticide: Herbicide

Target organism(s): A wide variety of broadleaf weeds and aquatic weeds

Mode of action: 2,4-D is thought to increase cell-wall plasticity, biosynthesis of proteins and the

production of ethylene. The abnormal increase in these processes is thought to result in uncontrolled

cell division and growth which damages vascular tissue. 

Use Sites: Table 3 presents a summary of the registered 2,4-D uses. 

Use Classification: General use

Formulation Types: Formulation types registered include emulsifiable concentrate, granular, soluble

concentrate/solid, water dispersible granules, and wettable powder. 

Application Methods: 2,4-D may be applied with a wide range of application equipment including

fixed-wing aircraft, backpack sprayer, band sprayer, boom sprayer, granule applicator, grounddirected sprayers, hand held sprayer, helicopter, injection equipment, tractor-mounted granule

applicator, and tractor-mounted sprayers. 

Application Rates: For 2,4-D, rates per application and rates per year are generally less than 1.5

pounds acid equivalent (ae) per acre per year and 2.0 pounds a.e. per acre per year (lbs ae/A),

respectively. Maximum rates are 4.0 lbs ae/A per year for asparagus, forestry uses, and non-cropland

uses, among others. The maximum rate for aquatic uses is 10.8 lbs ae/acre foot for submerged

aquatic plants. 

Application Timing: Timing of 2,4-D application can include at emergence, before bud break,

during dormancy, to established plantings, foliar, post-emergence, pre-emergence, pre-harvest, and

pre-plant. 
Page 9 of 304

Table 3. Registered 2,4-D Uses

Crop Grouping Representative Crops

Terrestrial food crop Pear, Pistachio, Stone fruits

Terrestrial food and feed

crop

Agricultural fallow/idleland; Agricultural rights-of-way/fencerows/hedgerows;

Agricultural uncultivated areas; Apple; Barley; Citrus fruits; Corn (unspecified);Corn,

field; Corn, pop; Corn, sweet; Fruits (unspecified), Grapefruit, Lemon, Oats, Orange, Pome

fruits, Rice, Rye, Small fruits, Soil, preplant/outdoor, Sorghum, Sorghum (unspecified),

Soybeans (unspecified), Sugarcane, Tangelo, Tree nuts, Wheat

Terrestrial feed crop Grass forage/fodder/hay, Pastures, Rangeland, Rye, Sorghum

Terrestrial non-food crop 

 

Agricultural fallow/idleland, Agricultural rights-of-way/fencerows/hedgerows,

Agricultural uncultivated areas, Airports/landing fields, Christmas tree plantations,

Commercial/industrial lawns, Commercial/institutional/industrial, premises/equipment

(outdoor), Forest nursery plantings (for transplant purposes), Golf course turf, Grasses

grown for seed, Industrial areas (outdoor), Nonagricultural outdoor buildings/structures,

Nonagricultural rights-of-way/fencerows/hedgerows, Nonagricultural uncultivated

areas/soils, Ornamental and/or shade trees, Ornamental lawns and turf, Ornamental sod

farm (turf), Ornamental woody shrubs and vines, Paved areas (private roads/sidewalks),

Potting soil/topsoil, Recreation area lawns, Recreational areas, Soil, preplant/outdoor,

Urban areas 

Terrestrial non-food and

outdoor residential 

 

Fencerows/hedgerows, Nonagricultural rights-of-way/fencerows/hedgerows, Ornamental

and/or shade trees, Ornamental lawns and turf, Ornamental woody shrubs and vines,

Paths/patios, Paved areas (private roads/sidewalks), Urban areas 

Aquatic food crop 

 

Agricultural drainage systems, Aquatic areas/water, Commercial fishery water systems,

Irrigation systems, Lakes/ponds/reservoirs (with human or wildlife use), Rice,

Streams/rivers/channeled water, Swamps/marshes/wetlands/stagnant water

Aquatic non-food

outdoor 

Aquatic areas/water, Streams/rivers/channeled water,

Swamps/marshes/wetlands/stagnant water

Aquatic non-food

industrial 

Drainage systems, Industrial waste disposal systems, Lakes/ponds/reservoirs (without

human or wildlife use) 

Forestry Conifer release, Forest plantings (reforestation programs)(tree farms, tree plantations,

etc.), Forest tree management/forest pest management, Forest trees (all or unspecified),

Forest trees (hardwoods, broadleaf trees), Pine (forest/shelterbelt) 

Outdoor residential Residential lawns

Indoor non-food Commercial transportation facilities-nonfeed/nonfood

D. Estimated Usage of Pesticide

Based primarily on pesticide usage information from 1992 through 2000 for agriculture and

1993 through 1999 for non-agriculture, total annual domestic usage of 2,4-D is approximately 46

million pounds, with 30 million pounds (66%) used by agriculture and 16 million pounds (34%) used

by non-agriculture (see the OPP Biological and Economic Assessment Division [BEAD] quantitative

use analysis [QUA] which is available on EPA’s Pesticide Docket OPP-2004-0167 located at:
Page 10 of 304

http://www.epa.gov/edockets). In terms of pounds, total 2,4-D usage is allocated mainly to

pasture/rangeland (24%), lawn by homeowners with fertilizer (12%), spring wheat (8%), winter

wheat (7%), lawn/garden by lawn care operators/landscape maintenance contractors (7%), lawn by

homeowners alone (without fertilizer) (6%), field corn (6%), soybeans (4%), summer fallow (3%),

hay other than alfalfa (3%), and roadways (3%). 

Agricultural sites with at least 10% of U.S. acreage treated include spring wheat (51%), filberts

(49%), sugarcane (36%), barley (36%), seed crops (29%), apples (20%), rye (16%), winter wheat

(15%), cherries (15%), oats (15%), millet (15%), rice (13%), soybeans (12%) and pears (10%). For

2,4-D, rates per application and rates per year are generally less than 1.5 lbs ae/A per year and 2.0 lbs

ae/A per year, respectively. 2,4-D is used predominantly in the Midwest, Great Plains, and

Northwestern United States (Figure 1).
Figure 1. Estimated 2,4-D usage (lbs ae/square mile). The estimates are based on pesticide use rates 

by the National Center for Food and Agricultural Policy (NCFAP) and modified by Thelin, G.P. and GL.P., 2000 (USGS Open-File Report 00-250)
Page 12 of 304

Application Rates, Timing and Frequency of Applications

The 2,4-D master label (available in EPA docket #OPP-2004-0167) has been developed by the

2,4-D Task Force and represents the maximum supported application rates for agricultural and nonagricultural uses. All end-use product manufacturers obtain 2,4-D starting material from companies

represented by the 2,4-D Task Force. EPA used the master label rates in the 2,4-D human health and

ecological risk assessments. Some master label rates are lower than the rates present on existing

labels. The Agency and the task force have agreed that all of the 2,4-D labels will be updated with

the new master label rates as part of the registration process. All of the registrants, including those

that are not in the 2,4-D task force, will have to conform to the master label rates. The master label

agreement is discussed in an internal Agency memo (EPA, March 18, 2003), which is available on

EPA’s Pesticide Docket OPP-2004-0167 located at: http://www.epa.gov/edockets. 

Typically, one to three applications are made per growing season. Applications are made to the

target weeds prior to crop emergence, after crop emergence, prior to harvest, and in the dormant

season, depending upon the crop. The label required spray volumes for ground applications range

from 0.0375 lbs ae/A for applications to low bush blueberries to 4.0 lbs ae/A for brush control. 2,4-D

can be applied over the top to tolerant crops such as small grains and rice, but must be directed or

shielded for the more sensitive crops such as fruits and berries.

The application rates on the master label are included in Table 4 for non-crop areas and Table 5

for agricultural crops. The average application rates from the 2,4-D QUA report (EPA BEAD 2001)

are shown for comparison. With the exception of filberts, the QUA data indicate that only one

application is made to most crops. The National Agricultural Pesticide Impact Assessment Program

(NAPIAP) report on Phenoxy Herbicides indicates that on average one 2,4-D application is made

annually to turfgrass.

Table 4. 2,4-D Application Rates for Non-Crop Areas

Aquatic Areas, Forestry, Non-Crop Areas and

Turf

Acid Equivalent lbs (ae) Application Rates

Per Application/Per crop or Year

Master Label Amount Used per QUA

Report

Aquatic Areas - Floating Weeds 2.0/4.0 per acre 512,000 lbsA

Aquatic Areas - Submerged Weeds 10.8 per acre foot

Tree and Brush Control - Tree Injection 1 to 2 ml per inch of trunk diameter 136,000 lbs

Forestry - Weed and Brush Control 4.0/4.0 per acre

Forestry - Conifer Release 4.0/4.0 per acre

Irrigation Ditch Banks 2.0/4.0 per acre

Rights of Way Areas 2.0/4.0 per acre 2.1 million lbs

Rangeland, Pastures 2.0/4.0 per acre

Turf - Grass Grown for Seed or Sod 2.0/4.0 per acre 351,000 lbs
Aquatic Areas, Forestry, Non-Crop Areas and

Turf

Acid Equivalent lbs (ae) Application Rates

Per Application/Per crop or Year

Master Label Amount Used per QUA

Report

Page 13 of 304

Turf - Ornamental 2.0/4.0 per acre B 11.6 million lbs

A. According to the NAPIAP report about 98,000 acres were treated for floating weeds and about 5,000 acres were treated for

submerged weeds by state agencies in 1993.

B. The registrants have agreed to reduce the ornamental turf rate from 2.0 to 1.5 lbs ae per acre. The new maximum yearly rate

will be 3.0 lbs ae per acre. 

Table 5. 2,4-D Application Rates for Agricultural Crops

Agricultural Crops Acid Equivalent lbs (ae) Application Rates per Acre

Per Application/Per crop or Year

Master Label Average Rate per QUA Report

Asparagus 2.0/4.0 1.1/1.3

Blueberries - Low Bush Wiper Bar 0.0375 lb/GA 0.46/0.51

Blueberries - High Bush 1.4/2.8

Citrus (Growth Regulator) 0.1 No Data

Conifer Plantations 4.0/4.0 No Data

Corn (sweet)

Corn (field and pop)

0.5 to 1.0/1.5

0.5 to 1.5/3.0

0.48/0.51

0.44/0.46

Cranberries - granular applications

Cranberries - liquid applications 

4.0/4.0 dormant season application

1.2/2.4 growing season application

1.8/2.0

Fallowland and Crop Stubble 2.0/4.0 0.69/0.89

Filberts 1.0 lb per 100 Ga/4 Apps per year 0.64/1.7

Grain Sorgum 0.5 to 1.0/1.0 0.46/0.50

Grapes 1.36/1.36 0.73/0.87

Orchard Floors (Pome and Stone Fruits,

Tree Nuts)

2.0/4.0 Apples = 1.2/1.4

Pears = 1.1/1.5

Potatoes 0.07/0.14 0.10/0.17

Rice 1.0 or 1.5/1.5 0.92/0.94

Soybeans (Preplant burndown) 0.5 or 1.0/1.0 0.46/0.47

Strawberries (Except CA or FL) 1.5/1.5 1.2/1.3

Sugarcane 2.0/4.0 0.75/0.99

Cereal Grains 

(Wheat, Barley, Millet, Oats and Rye)

0.5 or 1.25/1.75 Wheat= 0.44/0.48

Barley =0.46/0.47

Oats = 0.46/0.46

Rye = 0.50/0.50

Millet= 0.44/0.44
Agricultural Crops Acid Equivalent lbs (ae) Application Rates per Acre

Per Application/Per crop or Year

Master Label Average Rate per QUA Report

Page 14 of 304

Wild Rice (MN only) 0.25/0.25 0.20/0.20
Page 15 of 304

III. Summary of 2,4-D Risk Assessment

The following is a summary of EPA’s human health and ecological risk findings and

conclusions for 2,4-D, as presented fully in the documents “2,4-D. HED’s Revised Human Health

Risk Assessment for the Reregistration Eligibility Decision (RED) Revised to Reflect Public

Comments” dated May 12, 2005, and the “Environmental Fate and Effects Division’s Risk

Assessment for the Reregistration Eligibility Decision for 2,4-D,” dated October 28, 2004. 

The purpose of this section is to summarize the key features and findings of the risk assessment

in order to help the reader better understand the risk management decisions reached by the Agency.

While the risk assessments and related addenda are not included in this document, they are available

in the public docket OPP-2004-0167, and on the Agency's website at

http://www.epa.gov/pesticides/reregistration/status.htm

A. Human Health Risk Assessment

EPA released its preliminary risk assessments for 2,4-D for public comment on June 23, 2004,

thereby starting Phase 3 of a six phase public participation process. In response to comments

received during Phase 3, the human health risk assessment was updated. EPA issued the revised risk

assessments for 2,4-D for a second public comment period on January 12, 2005 (Phase 5 of the public

participation process). The risk assessments were revised again in response to Phase 5 public

comments, and are available for review.

The 2,4-D degradates detected in the various laboratory environmental fate studies were 1,2,4-

benzenetriol, 2,4-dichlorophenol (2,4-DCP), 2,4-dichloroanisole (2,4-DCA), 4-chlorophenol, 

chlorohydroquinone (CHQ), volatile organics, bound residues, and carbon dioxide. The OPP

Metabolism Assessment Review Committee (MARC) determined that all residues other than 2,4-D

are not of risk concern due to low occurrence under environmental conditions, comparatively low

toxicity, or a combination thereof. Therefore, the Agency assessed risks from 2,4-D per se. 

1. Toxicity of 2,4-D

With very few exceptions, the effects and relative toxicities of the salt and ester forms of 2,4-D

are quite similar to those of the acid form. Thus, the acid form was selected as being representative of

all members of the 2,4-D reregistration case (Case No. 0073). The member chemicals in the 2,4-D

case exhibit low to slight acute toxicity with the exception of the acid and salt forms being severe eye

irritants. The Agency has reviewed all toxicity studies submitted for 2,4-D and has determined that

the toxicological database is sufficient for reregistration. Further details on the toxicity of 2,4-D can

be found in the technical support documents cited in Appendix C.

a. Toxicity Profile

Major features of the toxicology profile are presented below. In acute studies, 2,4-D generally

has low acute toxicity (Toxicity Category III or IV) via the oral, dermal and inhalation routes of
Page 16 of 304

exposure. 2,4-D is not a skin irritant (Toxicity Category III or IV), nor a skin sensitizer. Although

the 2,4-D ester forms are not eye irritants (Toxicity Category III or IV), the acid and salt forms are

considered to be severe eye irritants (Toxicity Category I). The acute toxicity of all 2,4-D forms is

listed in Table 6. 

Table 6. Acute Toxicity Data for 2,4-D acid, 2,4-D ester forms, and 2,4-D amine salts1

.

Guideline

No.

Study Type MRID Numbers Results Toxicity Category

870.1100 Acute Oral

2,4-D acid

DEA salt

DMA salt

IPA salt

IPE ester

TIPA salt 

BEE ester

EHE ester

00101605

41920901

00157512

00252291

41709901

41413501

40629801

41209001

rat LD50 = 639 mg/kg

rat LD50 = 735 mg/kg

rat LD50 = 949 mg/kg

rat LD50 = 1646 mg/kg

rat LD50 = 1250 mg/kg

rat LD50 = 1074 mg/kg

rat LD50 = 866 mg/kg

rat LD50 = 896 mg/kg

III

III

III

III

III

III

III

III

870.1200 Acute Dermal

2,4-D acid

DEA salt

DMA salt

IPA salt

IPE ester

TIPA salt 

BEE ester

EHE ester

00101596

41920911

00157513

00252291

41709902

41413502

40629802

41209002

rabbits LD50 >2000 mg/kg

rabbits LD50 >2000 mg/kg

rabbit LD50 1829 mg/kg

rabbits LD50 >2000 mg/kg

rabbits LD50 >2000 mg/kg

rabbits LD50 >2000 mg/kg

rabbits LD50 >2000 mg/kg

rabbits LD50 >2000 mg/kg

III

III

III

III

III

III

III

III

870.1300 Acute Inhalation

2,4-D acid

DEA salt

DMA salt

IPA salt

IPE ester

TIPA salt 

BEE ester

EHE ester

00161660

41986601

00157514

40085501

40352701

41957601

40629803

42605202

rat LC50 >1.79 mg/L

rat LC50 >3.5 mg/L

rat LC50 >3.5 mg/L

rat LC50 =3.1 mg/L

rat LC50 >4.97 mg/L

rat LC50 =0.78 mg/L

rat LC50 =4.6 mg/L

rat LC50 >5.4 mg/L

III

IV

IV

IV

IV

III

IV

IV

870.2400 Primary Eye Irritation

2,4-D acid

DEA salt

DMA salt

IPA salt

IP ester

TIPA salt 

BEE ester

EHE ester

41125302

41920902

00157515

00252291

40352702

41413504

40629804

44725303

severe eye irritant

severe eye irritant

severe eye irritant

severe eye irritant

not an eye irritant

 severe eye irritant

not an eye irritant

not an eye irritant

I

I

I

I

IV

I

III

III

870.2500 Primary Skin Irritation

 2,4-D acid

DEA salt

DMA salt

IPA salt

IPE ester

TIPA salt 

BEE ester

EHE ester

42232701

41920903

00157516

00252291

40352703

41413505

40629805

41413505

unacceptable

slight skin irritant

slight skin irritant

slight skin irritant

slight skin irritant

slight skin irritant

very mild irritant

not a skin irritant

N/A

III

IV

IV

IV

IV

IV

IV
Guideline

No.

Study Type MRID Numbers Results Toxicity Category

Page 17 of 304

870.2600 Dermal Sensitization

2,4-D acid

DEA salt

DMA salt

IPA salt

IPE ester

TIPA salt 

BEE ester

EHE ester

00161659

41920904

41642805

41233701

40352704

41413506

40629806

41209006

not a dermal sensitizer

not a dermal sensitizer

unacceptable

unacceptable

not a dermal sensitizer

not a dermal sensitizer

not a dermal sensitizer

unacceptable

N/A

1. The technical acute toxicity values included in this document are for informational purposes only. The data supporting these values

will be evaluated during reregistration and may or may not meet the current Agency acceptance criteria.

The mechanisms responsible for renal clearance of 2,4-D have been investigated in several

species. 2,4-D is actively secreted by the proximal tubules. This mechanism of renal clearance is

consistent with results seen with other phenoxy acids. It has been suggested that observed dosedependent, non-linear, pharmacokinetics of 2,4-D are primarily due to the saturation of this renal

secretory transport system. Due to a limited capacity to excrete organic acids, the dog is more

sensitive to the effects of 2,4-D than the rat with respect to repeated dosing. 

In laboratory animals, following subchronic, oral exposure at dose levels of 2,4-D above the

threshold of saturation for renal clearance, the primary target organs are the eye, thyroid, kidney,

adrenals, and ovaries/testes. Changes in these organs are also observed following exposure to the

amine salts and esters of 2,4-D. Systemic toxicity was not observed following repeated dermal

exposure to 2,4-D, EHE, and TIPA at or above the limit dose or following repeated dermal exposure

to BEE and IPA at the highest dose tested. Liver toxicity was observed following repeated high-dose

dermal exposure to DEA, and one death occurred following repeated high-dose dermal exposure to

DMA.

There are no repeat-dose inhalation exposure data available on 2,4-D. The most reliable way to

characterize inhalation toxicity and to quantify inhalation risk is through the use of inhalation toxicity

studies. In general, chemicals tend to be more toxic by the inhalation route than by the oral route due

to rapid absorption and distribution, bypassing of the liver’s metabolic protection (portal circulation),

and potentially serious portal-of-entry effects, such as irritation, edema, cellular transformation,

degeneration, and necrosis. An inhalation risk assessment that is based on oral data generally

underestimates the inhalation risk because it cannot account for these factors. However, in the case of

2,4-D, based on the limited metabolism of 2,4-D via the oral route, the moiety to which the body

would be exposed would be the same for both routes of exposure. With regard to portal-of-entry

effects, these can only be assessed in an inhalation study. Therefore, a subchronic (28-day) inhalation

study is required for 2,4-D.

Developmental toxicity, characterized mainly as an increased incidence of skeletal

abnormalities in the rat, was observed following exposure to 2,4-D and its amine salts and esters at

dose levels that were at or above the threshold of saturation of renal clearance. Similarly,

developmental toxicity was observed in the rabbit only following exposure to 2,4-D (abortions) and

DEA (increased number of litters with fetuses having 7th cervical ribs) at or above the threshold of
Page 18 of 304

renal clearance.

Reproductive toxicity, characterized as an increase in gestation length, was observed following

exposure to 2,4-D at a dose level above the threshold of saturation of renal clearance. A repeat 2-

generation reproduction study (using the revised EPA protocol) is required to address concerns for

endocrine disruption. 

Neurotoxicity was demonstrated following exposure to 2,4-D at relatively high dose levels.

Clinical signs of neurotoxicity (ataxia, decreased motor activity, myotonia, prostration, lateral

recumbency, impaired/loss of the righting reflex, and skin cold to the touch) were observed in

pregnant rabbits following exposure to 2,4-D and its amine salts and esters. Neuropathology (retinal

degeneration) was observed following 2,4-D exposure in several studies in female rats. 

Incoordination and slight gait abnormalities (forepaw flexing or knuckling) were observed following

acute dosing and increased forelimb grip strength was observed following chronic exposure to 2,4-D

at dose levels that exceeded the threshold of saturation of renal clearance. A developmental

neurotoxicity study in the rat is required for 2,4-D.

2,4-D is classified as a Group D chemical (not classifiable as to human carcinogenicity). Based

on the overall pattern of responses observed in both in vitro and in vivo genotoxicity tests, 2,4-D was

not mutagenic, although some cytogenic effects were observed. 2,4-D acid is currently considered to

be representative of all nine member chemicals of the 2,4-D case.

The toxicological endpoints that were used to complete the risk assessments are summarized in

Table 7. These endpoints were selected by the Agency from animal studies. With respect to dermal

exposures, the Agency previously selected a dermal absorption factor of 5.8 percent based on the

average absorbed dose value from a human dermal absorption study. That factor (5.8 percent) was

used in previous versions of the human health risk assessment. Based on comments received during

the Phase 5 comment period, the dermal absorption study and resulting absorption factor were

reconsidered. In order to account for the variability observed in the dermal absorption study, the

dermal absorption factor was changed from 5.8 percent to 10 percent. In their “Re-evaluation of the

Lawn and Turf Uses of 2,4-D,” which was made available to the public for review, Health Canada

also selected a factor of 10 percent based upon the weight of evidence from several published studies,

taking into account the variability in the data and the limitations of the various studies. These studies

include the Feldman and Maibach study discussed above and studies from Harris and Solomon 1992,

Moody et. al. 1990, Wester et. al. 1996, and Pelletier et al. 1988.

b. Safety and Database Uncertainty Factors

The Food Quality Protection Act (FQPA) directs the Agency to use an additional tenfold (10X)

safety factor to protect for special sensitivity of infants and children to specific pesticide residues in

food, drinking water, or residential exposures, or to compensate for an incomplete database. FQPA

authorizes the Agency to modify the tenfold safety factor only if reliable data demonstrate that

another factor would be appropriate.

FQPA Special Safety Factor. After evaluating hazard and exposure data for 2,4-D, EPA
Page 19 of 304

removed the default 10X FQPA special safety factor. The toxicity database for 2,4-D includes

acceptable developmental and reproductive toxicity studies. Developmental toxicity studies were

conducted in both rats and rabbits for most 2,4-D forms. There is qualitative evidence of

susceptibility in the rat developmental toxicity study with 2,4-D acid and DEA salt where fetal effects

(skeletal abnormalities) were observed at a dose level that produced less severe maternal toxicity

(decreased body-weight gain and food consumption). There is no evidence of increased (quantitative

or qualitative) susceptibility in the prenatal developmental toxicity study in rabbits or in the 2-

generation reproduction study in rats on 2,4-D. Regarding the 2,4-D amine salt and ester forms, no

evidence of increased susceptibility (quantitative or qualitative) was observed in the prenatal

developmental toxicity study in rats and rabbits (except for 2,4-D DEA) dosed with any of the amine

salts or esters of 2,4-D. There is evidence of increased susceptibility (qualitative) in the prenatal

developmental study in rabbits for 2,4-D DEA salt.

After establishing developmental toxicity endpoints to be used in the risk assessment with

traditional uncertainty factors (10x for interspecies variability and 10x for intraspecies variability), the

Agency has no residual concerns for the effects seen in the developmental toxicity studies. Therefore,

the 10X FQPA special safety factor was reduced to 1X.

Database Uncertainty Factor. On April 8, 2003, based on the weight of evidence presented,

the Agency reaffirmed the previous conclusion that a developmental neurotoxicity (DNT) study in

rats is required for 2,4-D because there is a concern for developmental neurotoxicity resulting from

exposure to 2,4-D. There is evidence of neurotoxicity, including clinical signs such as ataxia and

decreased motor activity in pregnant rabbits following dosing during gestation days 6-15 in studies on

2,4-D itself and 2,4-D amine salts and esters, and tremors in dogs that died on test following repeat

exposure to 2,4-D. Incoordination and slight gait abnormalities (forepaw flexing or knuckling) were

also observed following dosing in the acute neurotoxicity study with 2,4-D. There is also evidence of

developmental toxicity, as discussed above in the FQPA Special Safety Factor section. In addition,

the Agency determined that a repeat 2-generation reproduction study using the new protocol is

required to address specific concerns for endocrine disruption (thyroid and immunotoxicity

measures). Therefore, the Agency determined that a 10X database uncertainty factor (UFDB) is

needed to account for the lack of these studies. 

c. Carcinogenicity

 A Science Advisory Board/Scientific Advisory Panel Special Joint Committee reviewed

available epidemiological and other data on 2,4-D in 1992 and concluded that “the data are not

sufficient to conclude that there is a cause and effect relationship between exposure to 2,4-D and nonHodgkin’s lymphoma.” 2,4-D has been classified as a Category D chemical (i.e., not classifiable as to

human carcinogenicity), by the EPA/OPP Cancer Peer Review Committee in 1996. The Agency

requested further histopathological examinations of rat brain tissues and mouse spleen tissues in

question. These exams were submitted and reviewed and on March 16, 1999, the Agency notified the

2,4-D Task Force that the Agency would continue to classify 2,4-D as a Group D carcinogen. 

The Agency has twice recently reviewed epidemiological studies linking cancer to 2,4-D. In

the first review, completed January 14, 2004, EPA concluded there is no additional evidence that
Page 20 of 304

would implicate 2,4-D as a cause of cancer (EPA, 2004). The second review of available

epidemiological studies occurred in response to comments received during the Phase 3 Public

Comment Period for the 2,4-D RED. This report, dated December 8, 2004 and authored by EPA

Scientist Jerry Blondell, Ph.D., found that none of the more recent epidemiological studies

definitively linked human cancer cases to 2,4-D. 

2,4-D Diethanolamine (DEA). The Agency recently reviewed the available toxicology data

on diethanolamine (DEA) and related compounds. The Agency concluded that it was not likely that

exposure to the DEA salt of 2,4-D resulting from occupational use would pose a carcinogenic risk to

humans. While liver tumors were observed in mice following dermal exposure to DEA, there was no

evidence of carcinogenicity in rats following dermal exposure, and there was no evidence of a

genotoxic or mutagenic concern. Although no formal assessment has been performed on the proposed

mode of action (choline deficiency), this mode of action was considered plausible for the mouse

hepatocellular tumors observed following dermal exposure to DEA, as were other confounding

factors, including the use of ethanol as a vehicle for dose administration and the fact that humans are

generally refractive to choline deficiency. Additionally, the low use pattern for 2,4-D DEA indicates

that there is no potential long-term dermal exposure to the diethanolamine salt of 2,4-D in agricultural

uses. The Agency also determined that, at this time, no carcinogenicity studies are required for the

DEA salt of 2,4-D.

d. Cumulative Assessment

FQPA requires EPA to consider "available information" concerning the cumulative effects of a

particular pesticide's residues and "other substances that have a common mechanism of toxicity"

when considering whether to establish, modify, or revoke a tolerance. Potential cumulative effects of

chemicals with a common mechanism of toxicity are considered because low-level exposures to

multiple chemicals causing a common toxic effect by a common mechanism could lead to the same

adverse health effect as would a higher level of exposure to any one of these individual chemicals. 

2,4-D is a member of the alkylphenoxy herbicide class of pesticides. A cumulative risk assessment

has not been performed as part of this human health risk assessment because the Agency has not yet

made a determination whether or not phenoxy herbicides have a common mechanism of toxicity. For

information regarding EPA’s efforts to determine which chemicals have a common mechanism of

toxicity and to evaluate the cumulative effects of such chemicals, see the policy statements released

by the EPA’s Office of Pesticide Programs concerning common mechanism determinations and

procedures for cumulating effects from substances found to have a common mechanism on EPA’s

website at http://www.epa.gov/pesticides/cumulative/

e. Endocrine Effects

EPA is required under the Federal Food, Drug, and Cosmetic Act (FDCA), as amended by the

Food Quality Protection Act (FQPA), to develop a screening program to determine whether certain

substances (including all pesticide active and other ingredients) "may have an effect in humans that is

similar to an effect produced by a naturally occurring estrogen, or other such endocrine effects as the

Administrator may designate."
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When the appropriate screening and/or testing protocols being considered under the Agency’s

Endocrine Disruption Screening Program (EDSP) have been developed, 2,4-D may be subject to

additional screening and/or testing to better characterize effects related to endocrine disruption.

Based on currently available toxicity data, which demonstrate effects on the thyroid and gonads

following exposure to 2,4-D, there is concern regarding its endocrine disruption potential. There have

been no studies on 2,4-D that specifically assess its endocrine disruption potential. The Agency has

determined that a repeat 2-generation reproduction study using the most recent protocol is required to

address both the concern for thyroid effects (comparative assessment between the young and adult

animals) and immunotoxicity, as well as a more thorough assessment of the gonads and

reproductive/developmental endpoints. 

f. Toxicological Endpoints for Risk Assessment

The toxicological endpoints used in the human health risk assessment for 2,4-D are listed in

Table 7. The safety factors used to account for interspecies extrapolation, intraspecies variability,

special susceptibility of infants and children, and database uncertainties are also described in Table 7

below. This table also describes any absorption factors used to extrapolate from one route of

exposure to another (e.g., oral to dermal). 

Table 7. Toxicity Endpoints for Human Health Risk Assessment for 2,4-D

Exposure

Scenario

Dose Used in Risk

Assessment, UF 

Special FQPA SF and Level of

Concern for Risk Assessment

Study and Toxicological Effects

Dietary Exposures

Acute Dietary

(Females 13-49

years of age)

MRID 00130407,

00130408

NOAEL = 25 mg/kg/day

UF = 1000

Acute RfD = 0.025

mg/kg/day

FQPA SF = 1X

aPAD = acute RfD(0.025)

 FQPA SF (1)

= 0.025 mg/kg/day

Rat Developmental Toxicity Study,

LOAEL = 75 mg/kg/day based on skeletal

abnormalities

Acute Dietary

(General

population

including infants

and children)

MRID 43115201

NOAEL = 67 mg/kg/day

UF = 1000

Acute RfD = 0.067

mg/kg/day

FQPA SF = 1X

aPAD = acute RfD (0.067)

 FQPA SF (1)

= 0.067mg/kg/day

Acute Neurotoxicity Study in Rats

LOAEL = 227 mg/kg/day based on gait

abnormalities

Chronic Dietary

(All populations)

MRID 43612001

NOAEL= 5 mg/kg/day

UF = 1000

Chronic RfD = 

0.005 mg/kg/day

FQPA SF = 1X

cPAD = chronic RfD (0.005)

 FQPA SF (1)

= 0.005 mg/kg/day

Rat Chronic Toxicity Study

LOAEL = 75 mg/kg/day based on

decreased body-weight gain (females) and

food consumption (females), alterations in

hematology , and clinical chemistry

parameters, decreased T4 (both sexes),

glucose (females), cholesterol (both sexes),

and triglycerides (females).

Occupational and Residential Non-Dietary Exposures
Exposure

Scenario

Dose Used in Risk

Assessment, UF 

Special FQPA SF and Level of

Concern for Risk Assessment

Study and Toxicological Effects

Page 22 of 304

Short-Term 

Incidental Oral (1-

30 days)

MRID 00130407,

00130408

NOAEL= 25 mg/kg/day Residential LOC for MOE

=1000

Occupational = NA

Rat developmental toxicity study

LOAEL = 75 mg/kg/day based on

decreased maternal body-weight gain

IntermediateTerm 

Incidental Oral (1-

6 months)

MRID 41991501

NOAEL = 15 mg/kg/day Residential LOC for MOE =

1000

Occupational = NA

Rat Subchronic Oral Toxicity 

LOAEL = 100 mg/kg/day based on

decreased body weight/body-weight gain,

alterations in some hematology, and

clinical chemistry parameters, and cataract

formation.

Short-Term

Dermal*

MRID 

00130407,

00130408

Oral study NOAEL= 25

mg/kg/day

Residential LOC for MOE 

= 1000

Occupational LOC for MOE =

100

Rat Developmental Toxicity Study

LOAEL = 75 mg/kg/day based on

decreased maternal body-weight gain and

skeletal abnormalities

IntermediateTerm

Dermal*

MRID 00130407,

00130408

Oral study NOAEL = 15

mg/kg/day

Rat Subchronic Oral Toxicity (same as for

intermediate-term incidental oral)

Long-Term

Dermal*

MRID 43612001

Oral study NOAEL= 5

mg/kg/day

Rat Chronic Toxicity Study (same as for

chronic dietary)

Short-Term

Inhalation*

MRID 

00130407,

00130408

Oral study NOAEL= 25

mg/kg/day

Rat Developmental Toxicity Study (same

as for short-term dermal)

IntermediateTerm Inhalation* 

MRID 00130407,

00130408

Oral study NOAEL = 15

mg/kg/day

Rat Subchronic Oral Toxicity (same as

intermediate-term incidental oral)

Long-Term

Inhalation*

MRID 43612001

Oral study NOAEL= 5

mg/kg/day

Rat Chronic Toxicity Study (same as for

chronic dietary)

Cancer Classification: Group D [not classifiable as to human carcinogenicity]

The dermal absorption factor is 10 percent and the inhalation absorption factor is 100 percent. 

UF = uncertainty factor, FQPA SF = Special FQPA safety factor, NOAEL = no observed adverse effect level, LOAEL = lowest

observed adverse effect level, PAD = population adjusted dose (a = acute, c = chronic), RfD = reference dose, MOE = margin of

exposure, LOC = level of concern, NA = Not Applicable

Dermal Absorption. A dermal absorption study utilizing human volunteers is available. 

Excretion following dermal application was 5.8 ± 2.4 percent (mean ± S.D.) of the administered dose

and after intravenous administration was 100 ± 2.5 percent. The Agency previously selected a dermal
Page 23 of 304

absorption factor of 5.8 percent based on the human dermal absorption study. This factor was used in

previous versions of this risk assessment. Based on comments received during the Phase 5 comment

period, this dermal absorption study and factor were reconsidered. In order to account for the

variability observed in the dermal absorption study, the dermal absorption factor was changed from

5.8 percent to 10 percent. In their “Re-evaluation of the Lawn and Turf Uses of 2,4-D,” which was

made available to the public, Health Canada also selected a factor of 10 percent based upon the

weight of evidence from several published studies, taking into account the variability in the data and

the limitations of the various studies. These studies include the Feldman and Maibach study

discussed above and studies from Harris and Solomon 1992, Moody et. al. 1990, Wester et. al. 1996,

and Pelletier et al. 1988.

2. Dietary Exposure and Risk from Food

a. Exposure Assumptions

Acute and chronic dietary exposure and risk analyses for 2,4-D were conducted using the

Lifeline TM Model Version 2.0 and Dietary Exposure Evaluation Model software with the Food

Commodity Intake Database (DEEM-FCIDTM, Version 1.33). DEEM incorporates consumption data

from USDA’s Continuing Surveys of Food Intakes by Individuals (CSFII), 1994-1996 and 1998. 

Lifeline TM uses food consumption data from the United States Department of Agriculture’s

(USDA’s) Continuing Surveys of Food Intakes by Individuals (CSFII) from 1994-1996 and 1998. 

LifelineTM uses recipe files contained within the program to relate raw agricultural commodities

(RACs) to foods “as-eaten.” LifelineTM converts the RAC residues into food residues by randomly

selecting a RAC residue value from the “user defined” residue distribution (created from the residue,

percent crop treated, and processing factors data), and calculating a net residue for that food based on

the ingredients’ mass contribution to that food item. 

LifelineTM models the individual’s dietary exposures over a season by selecting a new CSFII

diary each day from a set of similar individuals based on age and season attributes. LifelineTM groups

CSFII diaries based on the respondent’s age and the season during which the food diary was

recorded. Based on analysis of the 1994-96, and 1998 CSFII consumption data, which took into

account dietary patterns and survey respondents, the Agency concluded that it is most appropriate to

report risk for the following population subgroups: the general U.S. population, all infants (<1 year

old), children 1-2, children 3-5, children 6-12, youths 13-19, adults 20-49, females 13-49, and adults

50+ years old. The most highly exposed population subgroup for 2,4-D using both DEEM and

Lifeline was children 1-2 years of age.

The acute dietary assessment was only slightly refined as the following assumptions were

made: tolerance-level exposure values for most commodities, the highest field trial residue value for

citrus commodities, and 100% crop treated (%CT). Note that half of the average level of detection

(LOD) from the United States Department of Agriculture (USDA) Pesticide Data Program (PDP)

monitoring data was used as the milk residue value because no milk sample contained detectable 2,4-

D residues over several years of PDP sampling. 
Page 24 of 304

The chronic dietary assessment was moderately refined, making use of the following

assumptions: tolerance-level exposure values for most commodities; averages of field trial data and

processing study factors for small grains, citrus, and sugarcane sugar and molasses; %CT information

for all commodities; and the MCL (70 ppb) as well as the highest observed groundwater monitoring

concentration (15 ppb) for drinking water in a forward calculation. As in the case of the acute

assessment, half of the average LOD from PDP monitoring data was used for milk. 

b. Population Adjusted Dose

A population adjusted dose, or PAD, is the reference dose (RfD) adjusted for the FQPA safety

factor. A risk estimate that is less than 100% of the acute PAD (aPAD), the dose at which an

individual could be exposed over the course of a single day and no adverse health effects would be

expected, does not exceed EPA’s level of concern. Likewise, a risk estimate that is less than 100% of

the chronic PAD (cPAD), the dose at which an individual could be exposed over the course of a

lifetime and no adverse health effects would be expected, does not exceed EPA’s level of concern.

In the case of 2,4-D , the FQPA SF has been removed (equivalent to a factor of 1x), so the acute

or chronic RfD is identical to the respective aPAD or cPAD. In addition, an uncertainty factor is

determined for each chemical. In the acute and chronic dietary risk assessments for 2,4-D, the total

uncertainty factor (UF) is 1000x; 10x for interspecies variability, 10x for intraspecies variability, and

10x for database uncertainty. 

c. Food Risk Estimates

Acute: Risk to the general U.S. population was 18% and 17% of the aPAD using both DEEM

and Lifeline, respectively. The most highly exposed population subgroup using both DEEM and

Lifeline was children 1-2 years of age; risks were 33% and 32% of the aPAD, respectively. Risk to

females 13-49 years of age was 31% of the aPAD using DEEM and 42% of the aPAD using Lifeline;

these higher calculated risks for women of child-bearing age are due to the 2.7x lower toxicological

point of departure for developmental effects applicable to Females 13-49 years of age. These acute

dietary (food) risks are all less than the Agency’s level of concern (100% of the aPAD).

Chronic: Risk to the general U.S. population was 4.1% and 3.8% of the cPAD, using DEEM

and Lifeline, respectively. Risk to children 1-2 years of age, the most highly exposed population

subgroup, was 8.5% of the cPAD using DEEM and Lifeline.

3. Dietary Exposure and Risk from Drinking Water

Drinking water exposure to pesticides can occur through surface and ground water

contamination. EPA considers acute (one day) and chronic (lifetime) drinking water risks and uses

either modeling or monitoring data, if available and of sufficient quality, to estimate those exposures. 

In assessing drinking water risks, EPA compares model results to concentrations that would be

acceptable in drinking water from a human health perspective (e.g., DWLOCs). If the estimated

drinking water concentrations (EDWCs) in water are less than the DWLOCs, EPA does not have
Page 25 of 304

concern from consuming drinking water. If the EDWCs are greater than DWLOCs, EPA will

conduct further analysis to characterize the potential dietary risk from drinking water. Risks from

exposure to 2,4-D in drinking water are further discussed in the section III.A.5.

2,4-D is an herbicide used in a wide variety of environments. As the major route of degradation

is aerobic microbial metabolism, 2,4-D is non-persistent (t1/2=6.2 days) in terrestrial (aerobic)

environments, moderately persistent (t1/2=45 days) in aerobic aquatic environments, and highly

persistent (t1/2= 231 days) in anaerobic terrestrial and aquatic environments. Because 2,4-D will be

anionic (X-COO- H+) under most environmental conditions, it is expected to be mobile (Koc=61.7) in

soil and aquatic environments.

The 2,4-D degradates detected in the various laboratory environmental fate studies were 1,2,4-

benzenetriol, 2,4-dichlorophenol (2,4-DCP), 2,4-dichloroanisole (2,4-DCA), 4-chlorophenol, 

chlorohydroquinone (CHQ), volatile organics, bound residues, and carbon dioxide. The Agency has

determined that residues other than 2,4-D are not of risk concern due to low occurrence under

environmental conditions, comparatively low toxicity, or a combination thereof.

Estimated Environmental Concentrations (EEC) were derived through an evaluation of

monitoring data and modeling. A number of different scenarios were assessed and EECs provided

for each. Scenarios evaluated included the direct application of 2,4-D to water bodies for aquatic

weed control, a rice use scenario, and terrestrial uses including food and nonfood uses. 

a. Surface Water

Modeling: The Tier II screening models, Pesticide Root Zone Model and Exposure Analysis

Modeling System (PRZM-EXAMS),with the Index Reservoir and Percent Crop Area adjustment (IRPCA PRZM/EXAMS) were used to estimate 2,4-D residues in surface water used for drinking water.

The Index Reservoir represents a watershed that is more vulnerable than most watersheds used

as drinking water sources. It was developed from a watershed in western Illinois that has been used

for drinking water purposes. The Index Reservoir is used as a standard watershed that, in

combination with local soils types, weather conditions, and cropping practices, represents a

vulnerable watershed that could support a drinking water supply. 

For terrestrial uses of 2,4-D, EECs were calculated from aquatic exposure modeling using

PRZM/EXAMS with the Index Reservoir and a percent crop area treated (PCA) adjustment (Tier II). 

Fifteen scenarios were chosen for aquatic exposure modeling, including sugarcane in Florida; turf in

Florida and Pennsylvania; spring wheat in North Dakota; winter wheat in Oregon; corn in Illinois and

California; sorghum in Kansas and Texas; soybean in Mississippi; pasture in North Carolina; apples

in North Carolina, Oregon, and Pennsylvania; and filberts in Oregon. Although this only represents a

portion of the crops for which 2,4-D has a labeled use, it does represent crops with higher application

rates and crops which have a large percentage of their total acreage treated with 2,4-D. 

Surface water concentrations were modeled using PRZM version 3.12 and EXAMS version
Page 26 of 304

2.98.04. Ground water concentrations were modeled using SCIGROW version 2.2. The 15 crop

scenarios listed above were modeled using PRZM/EXAMS. Based on the maximum modeled

values, (more specifically, the North Carolina apple model scenario), the model-estimated, surfacewater-derived drinking water concentrations for the use of 2,4-D are:

118 ug/L for the 1 in 10 year annual peak concentration (acute) 

 64 ug/L for the 1 in 10 year 90-day average

 23 ug/L for the 1 in 10 year annual mean concentration (chronic)

Monitoring: Monitoring data considered in the assessment were the United States Geological

Survey’s (USGS) National Water Quality Assessment Program (NAWQA) groundwater and surface

water database, USGS/EPA reservoir monitoring database, National Drinking Water Contaminant

Occurrence Database (NCOD), and US EPA’s Storage and Retrieval environmental data system

(STORET). Review of these databases was conducted to provide peak and median concentrations. 

Additionally, the quality of data was evaluated for targeting pesticide use areas, detection limits, and

analytical recoveries. The monitoring data indicate that 2,4-D is detected in groundwater and surface

water. Also, 2,4-D is detected in finished drinking water. Maximum concentrations of 2,4-D in

surface source water and ambient groundwater are 58 ug/L and 14.8 ug/L, respectively. The highest

median 2,4-D concentration of 1.18 ug/L was derived from finished water samples in the NCOD

database. The highest time weighted annual mean (TWAM) concentration was 1.45 ug/L from the

NAWQA database containing nontargeted data reflecting pesticide concentrations in flowing water as

opposed to more stationary bodies of water such as ponds, lakes, and reservoirs.

The PRZM/EXAMS surface water-derived drinking water model estimate that would be

appropriate for acute exposure (118 ug/L) is approximately two times the peak concentration of 58

ug/L detected in the surface water monitoring data evaluated as part of this assessment. However,

since 70 ug/l is the current maximum contaminant level (MCL) established under the Safe Drinking

Water Act, and is the label-prescribed 2,4-D concentration in treated water to be used for drinking

water, this MCL limit is a reasonable and practical value to be used for the surface water

concentration of 2,4-D for acute risk assessment purposes. 

Note that the peak surface water concentration of 58 ug/L is consistent with the 70-ppb label

instruction (also the MCL). Although the surface water monitoring was not specifically targeted to

known 2,4-D- treated sites or even areas of high 2,4-D usage, this agreement suggests that, from a

practical standpoint, the MCL is a reasonable regulatory limit.

Although of high quality, the available monitoring data is not targeted to 2,4-D use. However,

the data provide context to model results and indicate that there is little evidence that concentrations

are likely to be found exceeding these levels. 

b. Ground Water

Monitoring: The maximum 2,4-D concentration detected in ground water is 14.89 ug/L based

on the USGS NAWQA program and 8 ug/L based on the NCOD monitoring data. The next highest
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concentration detected in the NAWQA groundwater data is 4.54 ug/L which is consistent with the

NCOD-reported concentration. Therefore, the Agency is using 15 ug/L based on monitoring for the

groundwater EDWC.

c. EDWCs Selected for Risk Assessment

The EDWCs for 2,4-D in surface and ground water are listed in Table 8 below. The EDWCs

were selected from both modeling calculations and monitoring data.

Table 8. Surface and Ground Water Estimated Drinking Water Concentrations (EDWCs)

Drinking Water Source Duration EDWC (ppb)

(ppb = ug/liter) Data Source

Surface Water

Acute (Peak)

70 ug/liter (aquatic

applications)

Maximum Contaminant

Level (MCL)

118 ug/liter (terrestrial

applications)

Modeling - PRZMEXAMS (NC apple

scenario)

Short and Intermediate

70 ug/liter (aquatic

applications)

Maximum Contaminant

Level (MCL)

64 ug/liter (terrestrial

applications)

Modeling - PRZMEXAMS (NC apple 1 in

10 year annual average)

Chronic

11 ug/liter (aquatic

application)

Modeling - Dissipation

modeling of aquatic

application

23 ug/liter (terrestrial

application)

Modeling - PRZMEXAMS worst case

terrestrial use (NC apple

scenario) 

1.5 ug/liter (terrestrial

application)

Monitoring - Maximum

time weighted annual

mean from NAWQA

database

Ground Water All Duration 15 ug/liter

Monitoring - Highest

monitored value from

NAWQA database

4. Residential and Other Non-occupational Exposure

 Residential exposure assessment considers all potential pesticide exposure, other than exposure

due to residues in foods or in drinking water. Exposure may occur during and after application on

lawns and turf, golf courses, parks, cemeteries, and other grass areas. Exposure may also occur to

recreational swimmers while swimming in waters treated with 2,4-D for aquatic weeds. Each route
Page 28 of 304

of exposure (oral, dermal, inhalation) is assessed, where appropriate, and risk is expressed as a

Margin of Exposure (MOE), which is the ratio of estimated exposure to an appropriate NOAEL. 2,4-

D products are marketed for homeowner use on residential lawns and turf. 2,4-D containing products

are also marketed for use by professional applicators on residential turf, golf courses, and on other

turf such as recreational or commercial areas. Based on these uses, 2,4-D has been assessed for the

residential mixing/loading/applicator (or “handler”) exposure for applications by homeowners to

home lawns. For post-application exposure, 2,4-D has been assessed for toddlers playing on treated

turf, adults performing yardwork on treated turf, adults playing golf on treated turf, and children and

adults swimming in bodies of water treated with 2,4-D for aquatic weed control. 

a. Toxicity

The toxicological endpoints, and associated uncertainty factors used for assessing the nondietary risks for 2,4-D are listed in Table 9.

In a dermal absorption study utilizing human volunteers, excretion following dermal application

was 5.8 ± 2.4% and after i.v. administration was 100 ± 2.5%. In previous risk assessments, the

Agency selected a dermal absorption factor of 5.8 percent based on the human dermal absorption

study. Based on comments received during the Phase 5 comment period, this dermal absorption

study and factor were reconsidered. In order to account for the variability observed in the dermal

absorption study, the dermal absorption factor was changed from 5.8 percent to 10 percent. In their

“Re-evaluation of the Lawn and Turf Uses of 2,4-D,” which was made available to the public, Health

Canada also selected a factor of 10 percent based upon the weight of evidence from several published

studies, taking into account the variability in the data and the limitations of the various studies. These

studies include the Feldman and Maibach study discussed above and studies from Harris and

Solomon 1992, Moody et. al. 1990, Wester et. al. 1996, and Pelletier et al. 1988.

Chronic endpoints were not used in the residential assessment because chronic occupational and

residential exposures to 2,4-D are not expected to occur. Per the 2,4-D Master Label, the maximum

label frequency for application of 2,4-D to turf is two times per year. 2,4-D also rapidly dissipates

from foliage and is readily excreted from the human body.

A MOE greater than or equal to 1000 is considered adequately protective for the residential

exposure assessment. The MOE of 1000 includes 10x for interspecies extrapolation, 10x for

intraspecies variation, and 10x for a database uncertainty factor. Table 9 lists the toxicity endpoints

selected for assessing residential risk for 2,4-D.

Table 9. Toxicity Endpoints Selected for Assessing Residential Risk for 2,4-D

Exposure

Scenario

Dose Used in Risk

Assessment, UF 

Level of Concern for

Risk Assessment

Study and Toxicological Effects

Occupational and Residential Non-Dietary Exposures
Exposure

Scenario

Dose Used in Risk

Assessment, UF 

Level of Concern for

Risk Assessment

Study and Toxicological Effects

Page 29 of 304

Short-Term 

Incidental Oral (1-30

days)

MRID 00130407,

00130408

NOAEL= 25 mg/kg/day

UFDB = 10

Residential LOC for

MOE =1000

Occupational = NA

rat developmental toxicity study

LOAEL = 75 mg/kg/day based on

decreased maternal body-weight gain

Intermediate-Term 

Incidental Oral (1- 6

months)

MRID 41991501

NOAEL = 15 mg/kg/day Residential LOC for

MOE = 1000

Occupational = NA

subchronic oral toxicity - rat

LOAEL = 100 mg/kg/day based on

decreased body weight/body-weight gain,

alterations in some hematology, and

clinical chemistry parameters, and

cataract formation.

Short-Term Dermal*

MRID 00130407,

00130408

Oral study NOAEL= 25

mg/kg/day

Residential LOC for

MOE 

= 1000

Occupational LOC for

MOE = 100

rat developmental toxicity study

LOAEL = 75 mg/kg/day based on

decreased maternal body-weight gain and

skeletal abnormalities

Intermediate-Term

Dermal*

MRID 00130407,

00130408

Oral study NOAEL = 15

mg/kg/day

subchronic oral toxicity - rat (same as for

incidental oral)

Long-Term Dermal*

MRID 43612001

Oral study NOAEL= 5

mg/kg/day

rat chronic toxicity study (same as for

chronic dietary)

Short-Term Inhalation*

MRID 00130407,

00130408

Oral study NOAEL= 25

mg/kg/day

rat developmental toxicity study (same as

for short-term dermal)

Intermediate-Term

Inhalation* 

MRID 00130407,

00130408

Oral study NOAEL = 15

mg/kg/day

subchronic oral toxicity - rat (same as

incidental oral)

Long-Term Inhalation*

MRID 43612001

Oral study NOAEL= 5

mg/kg/day

rat chronic toxicity study (same as for

chronic dietary)

Cancer Classification: Group D [not classifiable as to human carcinogenicity]

*The dermal absorption factor is 10 percent and the inhalation absorption factor is 100 percent. 

UF = uncertainty factor, FQPA SF = Special FQPA safety factor, NOAEL = no observed adverse effect level, LOAEL = lowest

observed adverse effect level, PAD = population adjusted dose (a = acute, c = chronic), RfD = reference dose, MOE = margin of

exposure, LOC = level of concern, NA = Not Applicable

b. Residential Handler

1) Exposure Scenarios, Data, and Assumptions

Homeowners (or others) may be exposed to 2,4-D while treating their lawns. All homeowneruse products are available in liquid or granular form. 2,4-D is applied using hose-end sprayers, pump

sprayers, ready-to-use sprayers, broadcast spreaders, bellygrinders, and hand application, either

before or after seasonal weed emergence, at a rate up to 1.5 lbs ae/A. A number of assumptions, or
Page 30 of 304

estimates, such as adult body weight and area treated per application, are made by the Agency for

residential risk assessment. Also, note that residential handlers are addressed somewhat differently

than occupational handlers in that homeowners are assumed to complete all elements of an

application (mix/load/apply) without use of personal protective equipment (assessments are based on

an assumption that individuals will be wearing short pants and short-sleeved shirts). 

The quantitative exposure/risk assessment developed for residential handlers is based on these

scenarios:

1) Hand application of granules

2) Belly grinder application

3) Load/apply granules with a broadcast spreader

4) Mix/load/apply with a hose-end sprayer (mix your own)

5) Mix/load/apply with a hose-end sprayer (ready-to-use)

6) Mix/load/apply with hand held pump sprayer

7) Mix/load/apply with ready-to-use sprayer

Exposure estimates for these scenarios are taken from the Pesticide Handlers Exposure

Database (PHED, Version 1.1 August 1998) which is used to assess handler exposures when

chemical-specific monitoring data are not available. In addition to PHED data, the residential risk

assessment relies on data from the Outdoor Residential Exposure Task Force (ORETF) and

proprietary studies. Three turf transferable residue studies submitted by the Broadleaf Turf Herbicide

Turf Transferable Residue (TTR) Task Force. These studies measured the dissipation of several

phenoxy herbicides, including 2,4-D, using the ORETF roller technique. Scenarios #1 through #5 use

ORETF or PHED data; scenarios #6 and #7 use exposure data from the Carbaryl 

Mixer/Loader/Applicator Exposure Study (EPA MRID 444598-01). 

The results of a biomonitoring study (Harris and Solomon 1992) were also used to calculate 

dermal MOEs for post application exposure on turf. The study was conducted with adult volunteers

who were exposed to 2,4-D while performing controlled activities for one hour on turf treated with

2,4-D. The controlled activities were conducted at 1 hour after treatment (HAT) and at 24 HAT. Ten

volunteers participated in the study. Five volunteers wore long pants, a tee shirt, socks and closed

footwear. The other five wore shorts and a tee shirt and were barefoot. The volunteers walked on the

turf for a period of 5 minutes and then sat or lay on the area for 5 minutes and then continued in this

fashion for 50 more minutes. Each volunteer collected all urine for the next 96 hours immediately

following the exposure. The MOEs for the DAT 1 volunteers who wore shorts and no shoes ranged

from 1000 to 26000 with the lowest MOE corresponding to a volunteer who removed his shirt during

the exposure period. The MOEs for the remaining volunteers ranged from 17000 to 27000. 

For more information, see “2,4-D. HED’s Revised Human Health Risk Assessment for the

Reregistration Eligibility Decision (RED) Revised to Reflect Public Comments. PC Code 030001;

DP Barcode D316597" dated May 12, 2005, and the “2,4-D: 3rd Revised Occupational and

Residential Exposure and Risk Assessment and Response to Public Comments for the Registration

Eligibility Decision (RED) Document” dated May 4, 2005.
Page 31 of 304

 Assumptions Regarding Residential Handlers

• Clothing would consist of a short-sleeved shirt, short pants and no gloves. 

• Broadcast spreaders and hose end sprayers would be used for broadcast treatments and the

other application methods would be used for spot treatments only.

C An area of 0.023 acre (1000 square feet) would be treated per application during spot treatments

and an area of 0.5 acre would be treated during broadcast applications.

C The application rate is 1.5 lb ae/acre representing the most recent revision to the master label.

C Average body weight of an adult handler is 70 kg.

C The duration of exposure is expected to be short-term (1-30 days) for residential handlers of

2,4-D. Intermediate- and long-term exposures of residential applicators are not anticipated

based on 2,4-D’s residential use pattern.

2) Residential Handler Risk Estimates

Based on toxicological criteria and potential for exposure, the Agency has conducted both a

dermal and an inhalation exposure assessment. Risk assessment for short-term inhalation exposure is

based on a rat developmental study. An assumption is made that 100% of the estimated inhalation

dose will be absorbed. A dermal absorption factor of 10 percent was selected for converting dermal

exposures to oral equivalent doses. An MOE greater than or equal to 1000 (10x for interspecies

extrapolation, 10x for intraspecies variation, and 10x for database uncertainty) is considered

adequately protective for this assessment. Since all residential handler MOEs are greater than 1000,

risk to residential handlers is not of concern. The 2,4-D risk estimates are presented in Table 10

below. 

In preliminary versions of the risk assessment, when considered alone, acute and short-term

residential risks posed by the use of 2,4-D were not of concern to the Agency; however, when

considered as part of an aggregate exposure with food and drinking water, exposures did exceed the

Agency’s level of concern. As a result, 2,4-D registrants agreed to reduce the maximum application

rate to turf and residential lawns from 2.0 lbs ae/A to 1.5 lbs ae/A. The revised application rate (1.5

lbs ae/A) was used in the current risk assessment. 

Table 10. 2,4-D Short Term Risk Estimates for Residential Handlers

Scenario Application Rate

(lbs ae/acre)

Treated Area

(acres/day)

MOE

1. Hand Application of Granules 1.5 0.023 3,700

2. Belly Grinder Application 1.5 0.023 3,900

3. Load/Apply Granules with a Broadcast Spreader 1.5 0.5 29,000

4. Mix/Load/Apply with a Hose-end Sprayer (Mix your own) 1.5 0.5 1,800

5. Mix/Load/Apply with a Hose-end Sprayer (Ready to Use) 1.5 0.5 7,400

6. Mix/Load/Apply with Hand Held Pump Sprayer 1.5 0.023 11,000
Scenario Application Rate

(lbs ae/acre)

Treated Area

(acres/day)

MOE

Page 32 of 304

7. Mix/Load/Apply with Ready to Use Sprayer 1.5 0.023 7,900

Note: 1000 square feet equals 0.023 acres

For more information, see Appendix F of “2,4-D: 3rd Revised Occupational and Residential

Exposure and Risk Assessment and Response to Public Comments for the Reregistration Eligibility

Decision (RED) Document (PC Code 030001, DP Barcode D316596)” dated May 4, 2005. 

c. Residential Postapplication Risk

1) Exposure Scenarios, Data, and Assumptions

2,4-D uses in the residential setting include applications to home lawns. The following

scenarios were assessed for residential post application risks:

1) Toddlers playing on treated turf

2) Adults performing yardwork on treated turf

3) Adults playing golf on treated turf

These scenarios chosen for risk assessment represent what the Agency considers the likely

upper-end estimates of possible exposure. An MOE of 1000 (or more) is considered protective for

this assessment. 

Assumptions Regarding Residential Postapplication Risk

• An assumed initial turf transferable residue (TTR) value of 5.0% of the application rate is used

for assessing hand to mouth exposures.

• An assumed initial TTR value of 20% of the application is used for assessing object to mouth

exposures.

• Soil residues are contained in the top centimeter and soil density (i.e., the ratio of the mass of

dry solids to the bulk volume of the soil occupied by those dry solids) is 0.67 gram/mL.

• Three year old toddlers are expected to weigh 15 kg.

• Hand-to-mouth exposures are based on a frequency of 20 events/hour and a surface area per

event of 20 cm2

 representing the palmar surfaces of three fingers.

• Saliva extraction efficiency is 50 percent. Every time the hand goes in the mouth

approximately half of the residues on the hand are removed.

• Adults are assessed using a transfer coefficient of 14,500 cm2

/hour. 

• Toddlers are assessed using a transfer coefficient of 5,200 cm2

/hour.

• Golfers are assessed using a transfer coefficient of 500 cm2

/hour.

• An exposure duration of 2 hours per day is assumed for toddlers playing on turf or adults

performing heavy yardwork.
Page 33 of 304

The following assumptions that are specific to 2,4-D are used for assessing residential post

application exposures.

C The master label application rate of 1.5 lbs ae/acre was used.

C The exposure following the application of granular formulations was not assessed because there

were no TTR data submitted for granular formulations. It was assumed this exposure would be

less than or equal to the exposure from liquid formulations.

Other residential exposure standard operating procedures (SOPs) may be viewed at the

following website: http://www.epa.gov/oscpmont/sap/1997/september/sopindex.htm . 

Calculation Method for Postapplication Exposure for Toddlers on Treated Turf

MOEs were calculated for acute toddler exposures using the maximum TTR value along with

the acute dietary NOAEL of 67 mg/kg/day. This NOAEL was adapted to acute dermal exposures by

using the dermal absorption factor of 10 percent to account for route to route extrapolation. The

MOEs for toddler short term exposures were calculated using the seven day average TTR value

because the short term NOAEL was based upon decreased body weight gain which occurred after

several days of exposure. MOEs for acute and adult short term exposures were calculated using the

maximum TTR value because the acute and short term NOAELs are the same and are based upon the

developmental effects which could have occurred following one day of exposure.

The quantitative exposure/risk assessment for postapplication risk to children is based on these

scenarios:

1) Dermal activity from treated turf: Postapplication exposure to children from the dermal

exposure of pesticide residues from activity on treated turf. 

2) Hand-to-mouth activity from treated turf: Postapplication exposure to children from the

“incidental” ingestion of pesticide residues on treated turf from hand-to-mouth transfer

(i.e., those residues that end up in the mouth from children touching turf and then putting

their hands in their mouths).

3) Object-to-mouth activity from treated turf: Postapplication exposure to children from

incidental ingestion of pesticide residues on treated turf from object-to-mouth transfer

(i.e., those residues that end up in the mouth from a child mouthing a handful of treated

turf).

4) Soil ingestion activity: Postapplication exposure to children from incidental ingestion of

soil in a treated area.

For more information on formulas used for calculating occupational and residential exposures

to 2,4-D, see Appendix A of “2,4-D: 3rd Revised Occupational and Residential Exposure and Risk

Assessment and Response to Public Comments for the Reregistration Eligibility Decision (RED)

Document” dated May 4, 2005. 

2) Postapplication Risk Estimates
Page 34 of 304

Risk assessment for children’s postapplication exposure is based on a NOAEL of 67 mg/kg/day

from an oral study of acute neurotoxicity study in rats. A Margin of Exposure (MOE) of 1000 (10x

for interspecies extrapolation, 10x for intraspecies variation, and 10x for database uncertainty) is

considered adequately protective for this assessment. Table 11 below presents the MOEs for PostApplication Exposure in Children. Since all MOEs meet or exceed 1000, postapplication exposure to

children is not of concern.

Table 11. Children Post-Application Exposure to Turf Treated with 2,4-D 

Application Rate

 (lbs ae/acre)

Dermal

MOE

Hand-to Mouth

MOE

Object to

Mouth MOE

Soil Ingestion

MOE

Total

MOE

Acute Toddler Risks Using the Maximum TTR (North Carolina Trial 1 using 2,4-D DMA)

DAT 0 1.5 1,900 3000 12,000 >100,000 1,100

Short Term Toddlers Risks Using California TTR Data (DMA Mix, No Rain)

DAT 0 to

DAT 6

1.5 3,900 2,100 8,500 >100,000 1,200

Short Term Toddler Risks Using North Carolina TTR Data from Trial 1 (DMA and DMA Mix, No Rain)

DAT 0 to

DAT 6

1.5 5,100 4,400 18,000 >100000 2,100

Short Term Toddler Risks Using North Carolina TTR Data from Trial 2 (DMA Mix, Some Rain)

DAT 0 to

DAT 6

1.5 12,000 7,000 28,000 >100000 3,900

The acute NOAEL is 67 mg/kg/day for neurotoxic effects observed in the acute neurotoxicity study.

The short term NOAEL is 25 mg/kg/day for maternal effects observed in the developmental study.

Table 12 below lists the adult acute/short term MOEs for exposure to turf treated with 2,4-D. 

The acute/short term NOAEL is 25 mg/kg/day from the rat developmental toxicity study. The

LOAEL was 75 mg/kg/day based on skeletal abnormalities from a developmental toxicity study in

rats. All MOEs meet or exceed 1000, so postapplication exposure to adults is not of concern.

Table 12. Adult Acute/Short Term MOEs for Exposure to Turf Treated with 2,4-D

Exposure Scenario Application Rate

(lbs ae/acre)

TTR (ug/cm2) Acute/Short Term Dermal MOE1

on Day 0

Heavy Yardwork

Playing Golf

1.5 0.50 1000

15000

1. The acute/short term NOAEL is 25 mg/kg/day for developmental effects observed in the developmental study.

d. Recreational Swimmer Risk
Page 35 of 304

1) Exposure Scenarios, Data, and Assumptions 

The master label indicates that 2,4-D can be used for aquatic weed control of surface weeds

such as water hyacinth and submersed weeds such as Eurasian milfoil. Surface weeds are controlled

by foliar applications at a maximum rate of 4.0 lb ae/acre. Submersed weeds are controlled by

subsurface injection of liquids to achieve a target concentration of 2 to 4 ppm in the water column

surrounding the weeds. This requires 5.4 to 10.8 lb ae per acre foot of water depth (e.g., 5.4 lbs ae

would be required to achieve 2 ppm in a one acre pond that has an average depth of 1 foot). Granular

formulations of BEE (Aquakleen and Navigate) are also used to control submersed weeds. The

granular formulations resist rapid decomposition in water and release the herbicide into the root zone.

Although many herbicide treatments are applied to aquatic areas where recreational swimming

is not likely to occur, some of the subsurface treatments are made at recreational lakes. These

treatments are made because the Eurasian milfoil interferes with recreation and other activities. This

problem is particularly prevalent in the northern states such as Minnesota and Washington and in the

New England region.

The following exposure scenarios are assessed for recreational swimmers:

1) Adult Recreational Swimmer

2) Child Recreational Swimmer

Assumptions Regarding Recreational Swimmer Risk

The following assumptions were used for the assessment of swimmer risks. Many of these

assumptions were taken from the Residential SOPs and are also used in the SWIMODEL.

C The skin surface area of adults is assumed to be 21,000 cm2 (Residential SOPs). This is

the 95th percentile value for females (EPA Exposure Factors Handbook, 1997). 

C The body weight for children is assumed to be 22 kg as cited in the Residential SOPs. 

This is a mean value for 6 year old children. 

C The skin surface area for children is assumed to be 9,000 cm2 as cited in the Residential

SOPs. This is the 90th percentile value for male and female children.

C The assumed mean ingestion rate is 0.05 liters per hour for both adults and children as

cited in the Residential SOP. This value may be greater for young children playing in

water and accidentally ingesting a remarkable quantity of water (U.S. EPA SAP, 1999).

C The exposure time is assumed to be 3 hours per day. This is the 90th percentile value for

time spent swimming in a freshwater pool (EPA Child Specific Exposure Factors

Handbook, 2002). 

C The body weight for female adult acute exposures is assumed to be 60 kg.

C The body weight for male adult acute exposures is assumed to be 70 kg.

C The body weight for adult short term exposure is assumed to be 60 kg because the

endpoint is gender specific.

C Risks were not calculated for foliar treatments because the application rate of 2.0 lb

ae/acre would result in water concentration of only 0.25 ppm in a three foot water column
Page 36 of 304

even if all of the spray were to run off the leaves into the water. 

Calculation Method for Recreational Swimmer Exposure

The Agency used the Swimmer Exposure Assessment Model (SWIMODEL) to calculate

exposures to swimmers in water treated with 2,4-D for aquatic weed control. The SWIMODEL

estimates exposure for up to six exposure routes (i.e., oral ingestion, dermal absorption, inhalation,

buccal/sublingual, nasal/orbital, and aural routes), or calculates exposure as a function of any one of

the three major exposure routes (i.e., oral ingestion, dermal absorption, or inhalation). Other factors

used in the SWIMODEL formulae for dermal and ingestion exposure which are described in

Appendix A of “2,4-D: 3rd Revised Occupational and Residential Exposure and Risk Assessment and

Response to Public Comments for the Reregistration Eligibility Decision (RED) Document” dated

May 4, 2005.

The SWIMODEL formulas for the other dermal pathways (aural, buccal/sublingual and

orbital/nasal) were not used in the 2,4-D human health risk assessment because these formulas are

based upon recreational swimmers in swimming pools who swim with their heads partially immersed. 

It is anticipated that recreational swimmers in weed infested areas would be less likely to swim with

their heads immersed than recreational swimmers in weed- free swimming pools. In addition, the

formulas for the buccal/sublingual and orbital/nasal pathways contain a default absorption factor of

0.01 which is based upon the absorption of nitroglycerin. This factor would greatly overestimate the

risk of 2,4-D exposure because 2,4-D is absorbed at a much lower rate. 

Because the 2,4-D water concentrations can vary depending upon the application rate and site

conditions the Maximum Swimming Water Concentration (MSWC) was calculated. The MSWC is

the water concentration at which the combined dermal and ingestion MOE meets or exceeds the

target MOE of 1000. The MSWCs were calculated for children’s acute exposures using the acute

NOAEL of 67 mg/kg/day and the MSWCs for children’s short term exposures were calculated using

the short term NOAEL of 25 mg/kg/day for maternal effects. The MSWCs for adult acute/short term

exposures were calculated using a NOAEL of 25 mg/kg/day that is based upon developmental effects

which could have occurred following one day of exposure. 

2) Recreational Swimmer Risk Estimates

The MSWCs are summarized in Table 13 and the detailed calculations are included in

Appendix H of the 3rd Revised Occupational and Residential Exposure Assessment for 2,4-D. The

acute MSWCs range from 1.2 ppm for 2,4-D BEE to 9.8 ppm for 2,4-D acid while the short term

MSWCs range from 0.9 ppm for 2,4-D BEE to 3.6 ppm for 2,4-D acid or amine. The MSWCs for

2,4-D BEE are lower because based on its chemical properties, 2,4-D BEE is expected to have a

much higher dermal absorption value. 
Page 37 of 304

Table 13. Maximum Swimming Water Concentrations for 2,4-D Aquatic Applications

Exposure Duration NOAEL

(mg/kg/day)

2,4-D Form 2,4-D MSWC*

(ppm)

Dermal

MOE

Ingestion

MOE

Combined

MOE

Adults

Acute/Short Term 25 Acid or Amine 9.8 97000 1000 1000

25 BEE 1.2 1200 8300 1000

Children

Acute 67 Acid or Amine 9.8 425000 1000 1000

Acute 67 BEE 2.4 1300 4100 1000

Short Term 25 Acid or Amine 3.6 230000 1000 1000

Short Term 25 BEE 0.90 1300 4100 1000

* The MSWC is the concentration below which the combined MOE would be above 1000 and the risks would not be of

concern.

The Acute MSWC of 9.8 ppm for exposures to 2,4-D acid or amine is greater than the master

label application rate of 4.0 ppm, therefore, acute exposures to 2,4-D acid or amine are not of

concern. The MSWC of 3.6 ppm for short-term exposures to 2,4-D acid or amine is also not of

concern because some dissipation or dispersion is likely to occur which would cause the 7-day

average of 2,4-D concentrations to be less than 3.6 ppm. Dissipation studies submitted to EFED

indicated that the half lives following pond and lake liquid treatments ranged from 3.2 days to 27.8

days which yield 7 day average concentrations of 1.9 ppm when the half life equals 3.2 days to 3.6

ppm when the half life equals 27.8 days. 

The MSWCs for 2,4-D BEE are less than the master label application rate of 4 ppm, but they

are unlikely to be of concern for the following reasons: 

C 2,4-D BEE degrades rapidly by abiotic hydrolysis in sterile water to form 2,4-D acid

particularly when the pH is 7.5 or above. 

C 2,4-D BEE degrades to 2,4-D acid by microbial hydrolysis with an average half life of 2.6 +

1.8 hours at a bacterial concentration of 5 x 10-8 organisms per liter. Therefore, degradation of 2,4-D

BEE to 2,4-D under typical environmental conditions will be rapid leading to significantly lower risk

estimates because the 2,4-D acid has a lower rate of dermal absorption.

C Modeling predicts direct water application of 2,4-D BEE will yield surface water concentrations

of 2,4-D BEE concentrations in the Agency standard pond of 624 ug/L for peak (24 hour average), 30

ug/L for the 21-day average, and 10 ug/L for the 60-day average. 

C The existing label rates for 2,4-D BEE products are also lower than the master label rate.
Page 38 of 304

5. Aggregate Exposure and Risk

OPP has traditionally compared estimates of concentrations of a pesticide in drinking water to

DWLOCs. A DWLOC is the portion of the acute PAD or chronic PAD remaining after estimated

dietary (food only) exposures have been subtracted and the remaining exposure has been converted to

a concentration (ug/L or ppb). This concentration value (DWLOC) represents the available or

allowable exposure through drinking water. In an acute risk assessment, the remaining portion of the

aPAD is based on dietary exposures at the percentile of exposure appropriate for a given risk

assessment and depends on each relevant population subgroup considered. Estimated Drinking

Water Concentrations (EDWCs) of 2,4-D in ground and surface water that are less than the DWLOCs

do not exceed the Agency’s level of concern. DWLOC values vary for population subgroups

depending on dietary exposure through foods for each subgroup, assumptions made about the volume

of drinking water consumed, and default body weights for each subgroup. 

More recently, OPP has adopted the forward calculation approach for the assessment of

aggregate risks. In this approach, food, drinking water and residential exposures are aggregated and

compared to an appropriate endpoint.

In the case of 2,4-D, the DWLOCs were calculated for comparison to the MCL established by

the EPA Office of Water and aggregate risks were calculated using the forward calculation approach

for comparison to the appropriate endpoint. The respective DWLOCs and aggregate risks are shown

for acute, chronic and short term exposures in the following sections.

a. Acute Aggregate Risk Assessment 

DWLOC Approach

Acute DWLOCs were calculated based upon acute dietary exposures. Acute residential

exposures from swimming in treated water bodies or playing on treated turf were not included

because exposures are unlikely to co-occur with acute dietary exposures. The acute DWLOCs are

summarized in Table 14 and are 432 ppb or greater with the most sensitive population being females

13-49 years old. The EDWCs of 118 ug/liter for surface water and 15 ug/liter for groundwater are

substantially less than the DWLOCs which means that the risks are not of concern. 
Page 39 of 304

Table 14. Acute DWLOC Calculations

Population

Subgroup Body Weight

(kg)

Water

Consumption

(liters/day)

aPAD

(mg/kg/day)

Food Exp1

(mg/kg/day)

Max Water

Exposure

(mg/kg/day2

)

DWLOC

(μg/L)3

General U.S.

Population

70 2.0

0.067

0.0118 0.0552 1932

All Infants (< 1

year old)

10 1.0 0.0132 0.0538 538

Children 1-2

years old

10 1.0 0.0221 0.0449 449

Children 3-5 years

old

10 1.0 0.0206 0.0464 464

Children 6-12

years old

10 1.0 0.0147 0.0523 523

Females 13-49

years old

60 2.0 0.025 0.0106 0.0144 432

1. Food exposure values are the maximum of the acute DEEM or Lifeline values.

2 .Maximum water exposure (mg/kg/day) = [(acute PAD - food exposure)]

3. DWLOC (μg/L) = [maximum water exposure x body weight] ÷ [water consumption x 10-3 mg/μg].

Surface Water EDWC = 70 ug/liter (aquatic applications) or 118 ug/liter (terrestrial applications)

Ground Water EDWC = 15 ug/liter

Forward Calculation Approach

Acute aggregate risks were assessed by aggregating acute food exposures and acute water

exposures. The acute aggregate risks are presented in Table 15 and are not of concern because they

are less than 100 percent of the aPAD. The highest risks (58 percent of the aPAD) are for females 13-

49 years old because these risks are based upon the lower NOAEL of 25 mg/kg/day.

Table 15. 2,4-D Aggregate Acute MOEs

Population

Subgroup

Body

Weight

(kg)

Water

Consumption

(liters/day)

Food

Exposure1

(mg/kg/day)

Drinking

Water

Exposure2

(mg/kg/day)

Aggregate

Exposure3

(mg/kg/day

)

aPAD4

(mg/kg/day

)

Percent

aPAD5

General U.S.

Population

70 2.0 0.0118 0.00337 0.0152 0.067 23

Females 13-49 yrs old 60 2.0 0.0106 0.0039 0.015 0.025 58

Notes for Table X

1. Food exposure values are the maximum of the DEEM or Lifeline acute values.

2. Drinking Water Exposure = (EDWC * daily water consumption) / (1000 ug/mg * Body Weight ); where the EDWC = 118 ug/liter

3. Aggregate Exposure = Food Exposure + Drinking Water Exposure

4. aPAD = NOAEL/1000; where the NOAEL is 25 mg/kg/day for females 13-49 and 67 mg/kg/day for all other population subgroups

5. Percent aPAD = (Aggregate Exposure/aPAD) * 100
Page 40 of 304

b. Chronic Aggregate Risk Assessment 

DWLOC Approach

Chronic DWLOCs were calculated based upon chronic dietary exposures. As there are no

chronic residential exposures, residential exposures were not included in the chronic DWLOC

calculations. The chronic DWLOCs are summarized in Table 16 and are 46 ug/liter or greater with

the most sensitive population being children. The EDWCs, which range from 1.5 to 23 ug/liter, are

less than the DWLOCs which means that the risks are not of concern. It should be noted that the

master label indicates that potable water consumption from a treated water body cannot begin until

the 2,4-D concentration is 70 ug/liter or below, therefore an annual average exposure at the MCL of

70 ug/liter would not occur because dissipation would reduce the initial concentration of 70 ug/liter to

an annual average concentration of 11 ug/liter.

Table 16. Chronic DWLOC Calculations

Population Subgroup Body

Weight

(kg)

Water

Consumption

(liters/day)

cPAD

(mg/kg/day)

Food Exp1

(mg/kg/day)

Max Water

Exposure

(mg/kg/day)2

DWLOC

(μg/L)3

General U.S. Population 70 2.0

0.005

0.00020 0.0048 168

All Infants (< 1 year old) 10 1.0 0.00016 0.00484 48

Children 1-2 years old 10 1.0 0.00042 0.00458 46

Children 3-5 years old 10 1.0 0.00037 0.00463 46

Children 6-12 years old 10 1.0 0.00026 0.00474 47

Youth 13-19 years old 60 2.0 0.00019 0.00481 144

Adults 20-49 years old 70 2.0 0.00019 0.00481 168

Adults 50+ years old 70 2.0 0.00018 0.00482 169

Females 13-49 years old 60 2.0 0.00020 0.0048 144

1. Food exposure values are the maximum of the DEEM or Lifeline chronic dietary values.

2. Maximum water exposure (mg/kg/day) = [(chronic PAD - food exposure)]

3. DWLOC (μg/liter) = [maximum water exposure x body weight] ÷ [water consumption x 10-3 mg/μg].

Surface Water EDWC (maximum time weighted annual mean from the NAWQA database) = 1.5 ug/liter

Surface Water EDWC (dissipation modeling of aquatic application when 70 ppb occurs at time zero) = 11 ug/liter

Surface Water EDWC (worst case terrestrial use PRZM-EXAMs run) = 23 ug/liter

Ground Water EDWC (the highest monitored value from the NAWQA database) = 15 ug/liter

Forward Calculation Approach

Chronic aggregate risks were also assessed by aggregating chronic food exposures and chronic

water exposures in a forward calculation approach. The chronic aggregate risks are presented as

percent cPAD in Table 17 and are not of concern because they are less than 100 percent of the cPAD. 

The highest risks (38 percent of the cPAD) are for children 1-2 years old.

Table 17. 2,4-D Aggregate Chronic Risks
Page 41 of 304

Population Subgroup Body

Weight

(kg)

Water

Consumption

(liters/day)

Food

Exposure1

(mg/kg/day)

Drinking

Water

Exposure2

(mg/kg/day)

Aggregate

Exposure3

(mg/kg/day

)

cPAD4

(mg/kg/day

)

Percent

cPAD5

General U.S. Population 70 2.0 0.00020 0.00043 0.0006 0.005 13

Children 1-2 yrs old 10 1.0 0.00042 0.0015 0.002 0.005 38

1. Food exposure values are from Table X and are the maximum of the DEEM or Lifeline chronic dietary values.

2. Drinking Water Exposure = (EDWC * daily water consumption) / (1000 ug/mg * Body Weight ); where the EDWC = 15 ug/liter

3. Aggregate Exposure = Food Exposure + Drinking Water Exposure

4. cPAD = NOAEL of 5 mg/kg/day / 1000

5. Percent cPAD = (Aggregate Exposure/aPAD) * 100

c. Short-term Aggregate Risk Assessments 

DWLOC Approach

Short-term aggregate risks assessments were conducted by calculating DWLOCs based upon

short term turf exposures, chronic food exposures and short term endpoints. Short-term exposures

from swimming in treated water bodies were not included because these exposures represent episodic

scenarios that are unlikely to occur the same day as an acute dietary exposure. The short-term

DWLOCs were calculated only for females 13-49 and children 1-6 because these population

subgroups have the highest exposure and are protective of the other subgroups. The DWLOCS are

listed in Table 18 and range from 24 to 54 ug/liter. These DWLOCs are all greater than the EDWCs,

which range from 15 to 23 ug/liter, and indicate that short term risks are not of concern.

Table 18. Short-Term DWLOC Calculations for 2,4-D

Pop.

Subgroup

Body

Weight

(kg)

Water

Consumption

(liters/day)

NOAEL/UF

(mg/kg/day)

Turf

Exposure

(mg/kg/day)

Food Exp1

(mg/kg/day)

Max Water

Exposure

(mg/kg/day)2

DWLOC

(μg/L)3

Children 1-6 15 1.0 0.025 0.021 0.00042 0.00358 54

Females 13-

49

60 2.0 0.025 0.024 0.00020 0.00080 24

1. Food exposure values are the maximum of the DEEM or Lifeline chronic dietary values.

2 Maximum water exposure (mg/kg/day) = [(NOAEL/UF) - (Turf exposure + food exposure)]

3. DWLOC (μg/liter) = [maximum water exposure x body weight] ÷ [water consumption x 10-3 mg/μg].

Surface Water EDWC (worst case terrestrial use PRZM-EXAMs run) = 23 ug/liter

Ground Water EDWC (based upon the highest monitored value) = 15 ug/liter

Forward Calculation Approach

Short-term aggregate risks were also assessed by directly aggregating short-term turf exposures,

chronic food exposures and chronic water exposures. Short-term aggregate risks were calculated only

for females 13-49 and children 1-6 because these population subgroups have the highest exposure and

are protective of the other subgroups. The short term aggregate MOEs are presented in Table 19 and

indicate that the short term risks are not of concern because the MOEs equal or exceed the target

MOE of 1000.
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Table 19. 2,4-D Aggregate Short-Term MOEs Including Turf Exposures

Population

Subgroup1 TurfApplication

Rate 

(lbs ae/acre)

Chronic

Food

Exposure2

(mg/kg/day)

Short-Term

Turf

Exposure3

(mg/kg/day)

Chronic

EDWC4

(ug/liter)

Drinking

Water

Exposure5

(mg/kg/day)

Aggregate

Exposure6

(mg/kg/day)

Aggregate

MOE7

Females 13 - 49 1.5 0.000195 0.024 15 0.00050 0.0247 1000

Children 1 - 6 1.5 0.000424 0.021 15 0.0010 0.0224 1100

Females 13 - 49 1.5 0.000195 0.024 23 0.00077 0.0250 1000

Children 1 - 6 1.5 0.000424 0.021 23 0.0015 0.0230 1100

1. Body weights are 60 kg (females) and 15 kg (children). Water consumption values are 2 liter/day (females) and 1.0 liter/day (children).

2. The food exposure for females is from Lifeline. The food exposure for children is from DEEM and is for 1-2 year old children

3. Female’s turf exposures are from the dermal route only. Children’s turf exposures are from the dermal and incidental oral routes.

4. EDWC is 15 ug/liter for ground water and 23 ug/liter for surface water. 

5. Drinking Water Exposure = (EDWC * daily water consumption) / (1000 ug/mg * Body Weight )

6. Aggregate Exposure = Turf Exposure + Food Exposure + Drinking Water Exposure

7. Aggregate MOE = NOAEL/Aggregate Exposure where the NOAEL is 25 mg/kg/day.

d. Cancer Aggregate Risk

2,4-D was classified as a Category D chemical, i.e., not classifiable as to human

carcinogenicity, by the EPA/OPP Cancer Peer Review Committee in 1996. Thus, no aggregate

cancer assessment is warranted. 

e. Aggregate Risk Characterization

The highest aggregate risks are the short term risks that include the turf exposure scenarios. 

For the most sensitive subpopulation (females 13-49), these risks just meet the target MOE of 1000

and the turf exposure is the risk driver as it contributes 96 percent of the risk. It is important to note,

however, that the turf exposure estimate is based upon modeling and is greater than exposure

measurements obtained from biomonitoring. The results of a biomonitoring study (Harris and

Solomon 1992) were also used to calculate dermal MOEs for post application exposure on turf. The

study was conducted with adult volunteers who were exposed to 2,4-D while performing controlled

activities for one hour on turf treated with 2,4-D. The controlled activities were conducted at 1 hour

after treatment (HAT) and at 24 HAT. Ten volunteers participated in the study. Five volunteers wore

long pants, a tee shirt, socks and closed footwear. The other five wore shorts and a tee shirt and were

barefoot. The volunteers walked on the turf for a period of 5 minutes and then sat or lay on the area

for 5 minutes and then continued in this fashion for 50 more minutes. Each volunteer collected all

urine for the next 96 hours immediately following the exposure. The MOEs for the DAT 1

volunteers who wore shorts and no shoes ranged from 1000 to 26000 with the lowest MOE

corresponding to a volunteer who removed his shirt during the exposure period. The MOEs for the

remaining volunteers ranged from 17000 to 27000. If the calculated MOE of 1000 is considered in

conjunction with the biomonitoring results, it is clear that the short term risks are upper bound

estimates and not likely to be of concern. 
Page 43 of 304

6. Occupational Risk

Workers can be exposed to a pesticide through mixing, loading, and/or applying a pesticide, or

re-entering treated sites. Occupational handlers of 2,4-D include workers in agricultural areas,

workers in forest areas, workers in rights-of-way and non-cropland areas, workers in lawn and turf

areas (including turf grown for seed or sod), and workers applying 2,4-D for aquatic weed control. 

Occupational risk for all of these potentially exposed populations is measured by an MOE which

determines how close the occupational exposure comes to a NOAEL. In the case of 2,4-D, MOEs

greater than 100 do not exceed the Agency’s level of concern. For workers entering a treated site,

MOEs are calculated for each day after application to determine the minimum length of time required

before workers can safely reenter. 

Occupational risk estimates are expressed as MOEs, which are the ratio of estimated exposure

to an established dose level (NOAEL). 2,4-D MOEs are determined by a comparison of specific

exposure scenario estimates to the NOAELs for short-term assessment and intermediate-term

assessment, respectively. The NOAEL for short-term dermal and inhalation exposure is 25

mg/kg/day from a rat developmental toxicity study, and the NOAEL for intermediate-term dermal

and inhalation exposure is 15 mg/kg/day from a rat subchronic oral toxicity study. The dermal

absorption factor is 10 percent and the inhalation absorption factor is 100 percent. For 2,4-D users an

MOE of 100 has been determined to be adequately protective (for both short- and intermediate-term

exposure) based on the standard uncertainty factors of 10x for interspecies extrapolation and 10x for

intraspecies variability. Long-term worker exposure is not expected for 2,4-D.

Occupational risk is assessed for exposure at the time of application (termed “handler”

exposure) and assessed for exposure following application, or postapplication exposure. Application

parameters are generally defined by the physical nature of the formulation (e.g., formula and

packaging), by the equipment required to deliver the chemical to the use site, and by the application

rate required to achieve an efficacious dose. Post-application risk is assessed for activities such as

scouting, irrigating, pruning, and harvesting and is based primarily on dermal exposure estimates. 

Occupational risk estimates are calculated based on assumptions concerning acres treated per

day and the seasonal duration of exposure. For more information on the assumptions and calculations

of potential risk of 2,4-D to workers, see the Occupational Exposure Assessment (Section 7.0) in

“2,4-D: 3rd Revised Occupational and Residential Exposure and Risk Assessment and Response to

Public Comments for the Reregistration Eligibility Decision (RED) Document,” dated May 4, 2005.

a. Occupational Toxicity

Table 20 provides a listing of the toxicological endpoints used in the 2,4-D occupational risk

assessment.
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Table 20. Toxicological Endpoints for the Occupational Risk Assessment

Exposure

Scenario

Dose Used in Risk

Assessment, UF 

Level of Concern

for Risk

Assessment

Study and Toxicological Effects

Short-Term Dermal* Oral study NOAEL= 

25 mg/kg/day

Occupational

LOC for MOE =

100

Rat developmental toxicity study

LOAEL = 75 mg/kg/day based on decreased maternal

body-weight gain and skeletal abnormalities

Intermediate-Term

Dermal*

Oral study NOAEL = 15

mg/kg/day

Subchronic oral toxicity - rat

LOAEL = 100 mg/kg/day based on decreased body

weight/body-weight gain, alterations in some

hematology, and clinical chemistry parameters, and

cataract formation.

Long-Term

Dermal*

Oral study NOAEL= 

5 mg/kg/day

Rat Chronic Toxicity Study

LOAEL = 75 mg/kg/day based on decreased bodyweight gain (females) and food consumption (females),

alterations in hematology , and clinical chemistry

parameters, decreased T4 (both sexes), glucose

(females), cholesterol (both sexes), and triglycerides

(females)].

Short-Term

Inhalation*

Oral study NOAEL= 25

mg/kg/day

Rat developmental toxicity study (same as for dermal)

Intermediate-Term

Inhalation* 

Oral study NOAEL = 15

mg/kg/day

Subchronic oral toxicity - rat (same as incidental oral)

Long-Term

Inhalation*

Oral study NOAEL= 5

mg/kg/day

Rat chronic toxicity study (same as for chronic dietary)

Cancer Classification: Group D [not classifiable as to human carcinogenicity]

*The dermal absorption factor is 10 percent and the inhalation absorption factor is 100 percent. 

UF = uncertainty factor, FQPA SF = Special FQPA safety factor, NOAEL = no observed adverse effect level, LOAEL = lowest observed adverse

effect level, PAD = population adjusted dose (a = acute, c = chronic), RfD = reference dose, MOE = margin of exposure, LOC = level of concern, NA

= Not Applicable

For more occupational toxicity information, see “2,4-D: HED’s Revised Human Health Risk

Assessment for the Reregistration Eligibility Decision (RED) Revised to Reflect Public Comments,”

dated January 4, 2005. 

b. Occupational Handler Exposure

Occupational handler risk estimates have been assessed for both short- and intermediate-term

exposure durations. Because 2,4-D is typically applied only a few times per season and because the

agricultural scenarios occur for only a few months per year, it is anticipated that 2,4-D exposures

would primarily be short-term. Intermediate-term risk estimates are provided as an upper-bound

assessment.

Occupational handler assessments are conducted using increasing levels of protection. The
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Agency typically evaluates all exposures with minimal protection and then considers additional

protective measures using a tiered approach (going from minimal to maximum levels of protection). 

The lowest tier is represented by the baseline clothing scenario (i.e., single layer clothing, socks, and

shoes), followed by, if MOEs are of concern, increasing levels of risk mitigation such as personal

protective equipment (PPE) and engineering controls (EC). With the exception of mixing and

loading wettable powders, MOEs for most occupational exposure scenarios are above 100 at baseline

PPE (long-sleeved shirt, long pants, socks, and shoes) or single layer PPE (long-sleeved shirt, long

pants, socks, shoes, and gloves). The MOEs for handling wettable powder are acceptable with

engineering controls (i.e. water soluble bags). While the generic assessment for 2,4-D as an active

ingredient does not indicate a need for additional PPE, evaluation of end-use product toxicity data

may. End-use product PPE will be assessed on a product-by-product basis. 

c. Occupational Handler Risk Summary

The Agency has determined that there are potential exposures to individuals who mix, load,

apply, and otherwise handle 2,4-D during the usual use patterns associated with the pesticide’s use. 

Based on the use patterns, 18 major occupational handler exposure scenarios were identified as

follows:

Mixer/Loader

(1a) Mix/Load Wettable Powder for Aerial Application

(1b) Mix/Load Wettable Powder for Groundboom Application

(1c) Mix/Load Wettable Powder for Aquatic Subsurface Application

(1e) Mix/Load Wettable Powder for 10 Man Crew Backpack Application

(1f) Mix/Load Wettable Powder for Row Sprayer

(1g) Mix/Load Wettable Powder for Aquatic Foliar Application

(1h) Mix/Load Wettable Powder for Turfgun Application

(2a) Mix/Load Liquids for Aerial Application

(2b) Mix/Load Liquids for Groundboom

(2c) Mix/Load Liquids for Aquatic Subsurface Application

(2d) Mix/Load Liquids for Airblast Application

(2e) Mix/Load Liquids for 10 Man Crew Backpack Application

(2f) Mix/Load Liquids for Row Sprayer

(2g) Mix/Load Liquids for Aquatic Foliar Application

(2h) Mix/Load Liquids for Turfgun Application

(3) Load Granules for Broadcast Spreader

Applicator

(4) Aerial Application

(5) Groundboom Application

(6) Subsurface Application of Liquids to Submersed Aquatic Weeds

(7) Airblast Application

(8) Backpack Application

(9) Rights of Way (ROW) Application
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(10) Foliar Application of Liquids to Floating Aquatic Weeds

(11) Turfgun Application

(12) Broadcast Spreader Application

Mixer/Loader/Applicator

(13) Mix/Load/Apply Wettable Powder with a Turfgun

(14) Mix/Load/Apply Liquids with a Turfgun

(15) Mix/Load/Apply Water Dispersable Granules with a Turfgun

(16) Mix/Load/Apply Liquids with a Backpack Sprayer

(17) Load/Apply Granules with a Push Spreader

Flagger

(18) Flag Aerial Application

Occupational Handler Exposure Assumptions

When possible, the assumptions for daily areas treated are taken from the Health Effects

Division Science Advisory Committee on Exposure Policy 9: Standard Values for Daily Acres

Treated in Agriculture (July 5, 2000). In other instances, the daily areas treated were defined for each

handler scenario by best scientific judgement, or the best information available, as footnoted below in

Table 21. 

Analyses were completed using acceptable surrogate exposure data for the scenario assessed. 

Several handler assessments were completed using data from the Pesticide Handler Exposure

Database (PHED) (version 1.1). PHED data were used primarily for the large scale agricultural and

forestry scenarios. Some handler assessments (i.e., handheld handgun equipment, push-type spreader,

and other lawn care scenarios) were completed using data from the Outdoor Residential Exposure

Task Force (ORETF). California Department of Pesticide Regulation (CA DPR) data were used for

the backpack applicator forestry scenario where multiple applicators are supplied by a nurse tank. 

The following assumptions and factors were used in order to complete the exposure and risk

assessments for occupational handlers and applicators:

C The average work day was 8 hours.

C A listing of application methods and amounts of acreage treated per 8 hour day is

included in Table 22 and Table 23. 

C The application rate for submerged aquatic weeds is based upon the master label rate of

10.8 lbs a.e. per acre foot times an average lake depth of 5 feet.

C Maximum application rates and daily acreage were used to evaluate short term exposures.

C Average application rates were used to evaluate intermediate term exposures.

C A body weight of 60 kg was assumed for short-term exposures because the short-term

endpoint relates to females 13-50 years of age.

C A body weight of 70 kg was assumed for intermediate-term exposures because the
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intermediate-term endpoint is not gender-specific.

C The dermal absorption rate is 10%.

C The inhalation absorption rate is 100%.

C Baseline PPE includes long sleeve shirts, long pants and no gloves or respirator.

C Single Layer PPE includes baseline PPE with gloves.

C Double Layer PPE includes coveralls over single layer PPE. 

C Double Layer PPE PF5 includes above with a PF5 respirator (i.e. a dustmask).

C Double Layer PPE PF10 includes above with a PF10 cartridge respirator.

C Only closed cockpit airplanes are used for aerial application.

C There are very little exposure data to evaluate the exposure in helicopters; therefore, the

exposure data for fixed-wing aircraft are used as a surrogate.

C Airplane and helicopter pilots do not wear chemical resistant gloves.

Table 21. 2,4-D Application Methods and Assumptions

Application Method Typical Crops Treated Treated Area1

Aerial Small Grain, Field Corn, Sugarcane

Citrus Growth Regulation

1200

350

Groundboom Small Grains, Field Corn, Sugarcane

Orchard/Vineyard Floors

Strawberries

200

80

80

Subsurface Application of Liquids Submersed Aquatic Weeds 302

Airblast Citrus Growth Regulation 40

Backpack Sprayer - Mix/Load/Apply Christmas Tree Plantations 23

Backpack Sprayer - Apply Only Conifer Release 44

Right of Way (ROW) Sprayer Weed Control - 20 gallons per acre

Brush Control - 400 gallons per acre

505

2.55

Foliar Application of Liquids Floating Aquatic Weeds 106

Broadcast Spreader - Tractor Drawn or Boat

Mounted

Turf 

Submersed Aquatic Weeds

40

507

Turfgun Turf 5

Broadcast Spreader - Push Type Turf 5

1. Except as noted, the acres treated per day values are from ExpoSAC Policy #9 “Standard Values for Daily Acres

Treated in Agriculture”, Revised 7/5/2000.

2. The area treated for aquatic application of liquids to submersed aquatic weeds is based on information provided in an

email of 12/11/03 from Dr. Kurt Getsinger of the US Army Corps of Engineers to Timothy C. Dole of the US EPA Office

of Pesticide Programs.

3. The area treated for Backpack Sprayer (Mix/Load/Apply) is 40 gallons per day from ExpoSAC Policy #9 divided by the

label recommended spray volume of 20 gallons per acre.

4. The area treated for Backpack Sprayer (Apply Only) is 4 acres per day based upon the acreage treated in CA DPR HS1769 normalized to an 8 hour day. 

5. The area treated for ROW sprayers was determined by the dividing the daily spray volume handled (1000 gallons per
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day) from ExpoSAC Policy #9 by the label recommended spray volume of 20 gallons per acre for weed control and 400

gallons per acre for woody brush control.

6. The area treated for foliar application of liquids to floating aquatic weeds is based upon use information reported in the

HED Memorandum “Occupational and Residential Exposure Characterization/Risk Assessment for Triclopyr

Triethylamine for Aquatic Weed Control, DP Barcode D269448 of 7/22/2002.

7. The area treated for application of granules to submersed aquatic weeds is based upon information provided in an email

of 11/22/2000 from Jim Kannenburg of Marine Biochemists/Applied Biochemists to Troy Swackhammer of the US EPA

Office of Pesticide Programs.

Summary of Risk Concerns and Data Gaps for Handlers

The MOEs for handlers are summarized in Tables 22 and 23 below. With the exception of

mixing/loading wettable powder, all of the short-term and intermediate-term MOEs exceed the target

of 100 with baseline PPE (i.e., long-sleeved shirt, long pants, shoes plus socks, no respirator) or single

layer PPE (i.e., long-sleeved shirt, long pants, shoes plus socks, gloves, no respirator) and are not of

concern. The MOEs for handling wettable powder are adequate with engineering controls (i.e. water

soluble bags). 

Table 22. MOEs for Short-Term Risk to Occupational Handlers

Exposure Scenario Crop Type Application

Rate 

(lb ae/acre)

Acres/

Day

Base-line Single

Layer 

Eng. 

Control 

Mixer/Loader (M/L)

M/L WP All Crops 0.25 to 4 5 to 1200 >1 >5 >260

M/L Liquids All Crops 0.25 to 4 5 to 1200 >1 >89 >330

M/L Liquids Submersed Weeds 54 30 3.2 260 980

Load Granulars for Broadcast

Spreader

Golf Courses and

Aquatic Areas

2 to 54 40 or 50 >220 >230 >1000

Applicator (APP) 

Aerial Application All Crops 1.25 to 4.0 1200 ND ND >550

Groundboom Application All Crops 1.25 to 4 40 to 200 >1000 >1000 >1000

Subsurface Aquatic Application of

Liquids

Submersed Weeds 54 30 430 430 >1000

Airblast Application Citrus 0.1 40 >1000 >1000 >1000

Backpack Application Conifer Release 4 4 ND 140 ND

ROW Application Weed Control 2 50 110 350 ND

Foliar Aquatic Application of

Liquids

Floating Weeds 2 10 280 870 ND

Turfgun Application turf 1.5 5 ND >1000 >1000

Broadcast Spreader Application Golf Courses and

Aquatic Areas

1.5 or 54 40 or 50 >250 >290 >1000

Mixer/Loader/Applicator (M/L/A) 
Exposure Scenario Crop Type Application

Rate 

(lb ae/acre)

Acres/

Day

Base-line Single

Layer 

Eng. 

Control 

Page 49 of 304

M/L/A Liquids with Backpack

Sprayer 

Christmas Trees 4 2 ND 730 ND

M/L/A WD Granules with a Turfgun turf 1.5 5 ND >1000 ND

M/L/A Wettable Powder with a Turf

Gun

turf 1.5 5 ND >1000 >1000

M/L/A Liquid Flowables with a

Turfgun 

turf 1.5 5 ND >1000 ND

Load/Apply Granules with a Push

Spreader 

turf 1.5 5 ND 710 ND

Flagger 

Flag Aerial Liquid Application All Crops 1.25 to 4.0 1200 >210 >200 >1000

MOEs in bold font do not exceed the target MOE of 100 and are of concern

ND not determined

Table 23. MOEs for Intermediate-Term Risk to Occupational Handlers

Exposure Scenario Crop Type Application

Rate 

(lb ae/acre)

Acres/

Day

Base-line Single

Layer 

Eng. 

Control 

Mixer/Loader (M/L)

M/L WP All Crops 0.25 to 4 5 to 1200 >1.1 >7.3 >360

M/L Liquids All Crops 0.25 to 4 5 to 1200 >1.5 >130 >460

M/L Liquids Submersed Weeds 54 30 2.2 190 690

Load Granulars for Broadcast

Spreader

Golf Courses or Aquatic

Areas

1.5 or 54 40 or 50 >150 >160 >1000

Applicator (APP) 

Aerial Application All Crops 0.5 to 2.0 1200 ND ND >770

Groundboom Application All Crops 0.5 to 4 40 to 200 >1000 >1000 >1000

Subsurface Aquatic Application Submersed Weeds 54 30 300 300 >1000

Airblast Application Citrus 0.1 40 >1000 >1000 >1000

Backpack Application Conifer Release 2 4 ND 200 ND

ROW Application Weed Control 2 50 78 240 ND

Foliar Aquatic Application of

Liquids

Floating Weeds and Wild

Rice

4 or 0.25 10 >200 >610 ND

Turfgun Application turf 1.5 5 ND >1000 ND

Broadcast Spreader Application Golf Courses and

Aquatic Areas

1.5 or 54 40 or 50 >180 >200 ND

Mixer/Loader/Applicator (M/L/A) 
Exposure Scenario Crop Type Application

Rate 

(lb ae/acre)

Acres/

Day

Base-line Single

Layer 

Eng. 

Control 

Page 50 of 304

M/L/A Liquids with Backpack

Sprayer 

Conifer Plantations 4 2 ND 510 ND

M/L/A WD Granules with a

Turfgun 

turf 1.5 5 ND >1000 ND

M/L/A Wettable Powder with a

Turf Gun

turf 1.5 5 ND >1000 >1000

M/L/A Liquid Flowables with a

Turfgun 

turf 1.5 5 ND >1000 ND

Load/Apply Granules with a Push

Spreader

turf 1.5 5 ND 500 ND

Flagger 

Flag Aerial Liquid Application All Crops 0.50 to 2.0 1200 >660 >610 >1000

MOEs in bold font do not exceed the target MOE of 100 and are of concern

d. Occupational Postapplication Risk

Post application 2,4-D exposures can occur in the agricultural environment when workers enter

fields recently treated with 2,4-D to conduct tasks such as scouting and irrigation. In the Worker

Protection Standard (WPS), a restricted entry interval (REI) is defined as the duration of time which

must elapse before residues decline to a level so entry into a previously treated area and engaging in a

specific task or activity would not result in exposures that are of concern. The WPS REI for 2,4-D is

12 hours for the ester and sodium salt forms and is 48 hours for the acid and amine salt forms.

1) Exposure Scenarios, Data, and Assumptions

Postapplication dislodgeable foliar residue (DFR) data were submittted for 2,4-D as well as turf

transferable residue (TTR) data from treated turf. Three turf transferable residue (TTR) studies were

submitted by the Broadleaf Turf Herbicide TTR Task Force. These studies are described in “2,4-D:

3rd Revised Occupational and Residential Exposure (ORE) and Risk Assessment and Response to

Public Comments for the Reregistration Eligibility Decision (RED) Document”dated May 4, 2005,

and in Appendix F of that document. These data were used in the human health risk assessment

along with standard transfer coefficients based on EPA Science Advisory Council guidance to assess

potential exposures to workers reentering treated sites.

For all other postapplication activities, EPA used the EPA Science Advisory Council for

Exposure (Exposure SAC) policy on agricultural transfer coefficients.

The following assumptions were made regarding postapplication occupational exposure:

• Short term risks were assessed using master label rates.

• Intermediate term risks were assessed using average application rates when available.
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C The transfer coefficients are from an interim transfer coefficient policy developed by HED’s

Science Advisory Council for Exposure using proprietary data from the Agricultural Re-entry

Task Force (ARTF) database (US EPA, August 7, 2001). This policy will be periodically

updated to incorporate additional information about agricultural practices in crops and new data

on transfer coefficients. Much of this information will originate from exposure studies currently

being conducted by the ARTF, from further analysis of studies already submitted to the

Agency, and from studies in the published scientific literature. 

C The transfer coefficients for turf harvesting and maintenance are based upon recently conducted

ARTF studies that are being reviewed by EPA. 

C In cases where applications would be made in such a way as to minimize contact with crop

foliage postapplication exposures are expected to be negligible and are not assessed. These

cases are included in “2,4-D: 3rd Revised Occupational and Residential Exposure and Risk

Assessment and Response to Public Comments for the Reregistration Eligibility Decision

(RED) Document (PC Code 030001, DP Barcode D316596)”, dated May 4, 2005.

• The initial percent of application rate as Dislodgeable Foliar Residue (DFR) was assumed to be

20% for all crops except turf. This is the standard value used in the absence of chemical specific

data.

2) Occupational Postapplication Risk Estimates

All short- and intermediate-term MOEs are above 100 on day zero. All occupational

postapplication risk scenarios are not of concern. Short-term and intermediate-term risk estimates are

shown in Tables 24 and 25 below. 

Table 24. 2,4-D Postapplication Short-Term Worker Risks

Crop Group ShortTerm MOE on Day 0

Application Rate 

(lb a.e./acre)

Low Exposure

Scenarios

Medium

Exposure

Scenarios

High

Exposure

Scenarios

 Field/row crop, low/med (cereal grains) 1.25 6,700 450 NA

 Field/row crop, low/med (rice) 1.5 5,600 370 NA

 Field/row crop, tall (corn)

Pre-harvest rate for field corn

Post-emergence rate for sweet corn

1.5

0.5

5,600

17,000

1,400

4,200

560

NA

 Field/row crop, tall (sorghum) 1.0 8,400 2,100 NA

Sugarcane 2.0 NA 420 210

Turf - California

Turf - North Carolina

2.0

2.0

1,900

 860

NA

NA

950

430
Page 52 of 304

Table 25. 2,4-D Postapplication Intermediate Term Worker Risks

Crop Group Intermediate Term MOE on Day 0

Application Rate+ 

(lb a.e./acre)

Low Exposure

Scenarios

Medium

Exposure

Scenarios

High

Exposure

Scenarios

 Field/row crop, low/med (cereal grains) 0.5 12,000 780 NA

 Field/row crop, low/med (rice) 0.92 6,400 420 NA

 Field/row crop, tall (field corn) 0.44 13,000 3,300 1,300

 Field/row crop, tall (sweet corn) 0.48 13,000 3,100 NA

 Field/row crop, tall (sorghum) 0.46 13,000 3,100 NA

Sugarcane 0.75 NA 780 390

Turf - California

Turf - North Carolina

2.0

2.0

1,600

610

NA

NA

810

300

+ Average application rates as reported in the QUA report or NASS report were used when available.

7. Human Incident Data

In evaluating incidents to humans, the Agency reviewed reports from the National Poison

Control Centers, the EPA OPP’s Incident Data System (IDS), the California Pesticide Illness

Surveillance Program, and the National Pesticide Telecommunications Network (NPTN). 

The Agency reviewed 2,4-D incident reports in January 2004. A total of 45 incidents were

reported in the OPP Incident Data System and many of these incidents involved irritant effects to the

eyes, skin and occasionally respiratory passages. Poison Control Center Incident Data (1993 to1998)

indicated that 2,4-D is generally less likely than other pesticides to cause minor, moderate or life

threatening symptoms. The most common symptoms were dermal irritation and ocular problems. 

Incident data from the California Pesticide Illness Surveillance Program indicated that the number of

cases generally ranges from 0 to 3 per year and most of these cases were due to eye or skin effects. 

Incident data from the National Pesticide Information Center for the years 1996 to 2002 indicated

that an average of 3 cases definitely or probably related to 2,4-D exposure were reported per year. 

8. Cancer Epidemiology Studies

A Science Advisory Board/Scientific Advisory Panel Special Joint Committee reviewed

available epidemiological and other data on 2,4-D in 1992 and concluded that “the data are not

sufficient to conclude that there is a cause and effect relationship between exposure to 2,4-D and nonHodgkin’s lymphoma” and 2,4-D was classified as a Group D, not classifiable as to human

carcinogenicity. The Agency has twice recently reviewed epidemiological studies linking cancer to

2,4-D. In the first review, completed January 14, 2004, EPA concluded there is no additional

evidence that would implicate 2,4-D as a cause of cancer (EPA, 2004). The second recent review of

available epidemiological studies occurred in response to comments received during the Phase 3

Public Comment Period during the reregistration process for 2,4-D. EPA’s report, dated December 8,
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2004 and authored by Jerry Blondell, Ph.D., found that none of the more recent epidemiological

studies definitively linked human cancer cases to 2,4-D. 

B. Environmental Risk Assessment

A summary of the Agency’s environmental risk assessment for 2,4-D is presented below. The

Agency has conducted an assessment of potential risks to aquatic and terrestrial organisms resulting

from the use of 2,4-D and its associated chemical forms including 2,4-D dimethylamine salt (2,4-D

DMAS), 2,4-D isopropylamine salt (2,4-D IPA), 2,4-D triisopropanolamine salt (2,4-D TIPA), 2,4-D

ethylhexyl ester (2,4-D EHE), 2,4-D butoxyethyl ester (2,4-D BEE), 2,4-D-diethanolamine salt (2,4-

D DEA), 2,4-D isopropyl ester (2,4-D IPE) and 2,4-D sodium salt. In this document, the term

“chemical form” is used to refer to the supported technical formulations listed above, while the term

“formulation” refers to the physical nature (e.g. granular or emulsifiable concentrate) of the applied

product, and the term “end use product” is used to refer to any formulated product including mixtures

of pesticide sold in the United States. 

2,4-D has the following registered uses, which result in environmental exposures:

pasture/rangeland, turf, wheat, corn, soybeans, fallowland, hay other than alfalfa, noncropland

(roadways, rights-of-way, ditches, industrial sites, etc.), forestry, rice, sugarcane, pome fruits, stone

fruits, nut orchards, filberts, grass grown for seed and sod, aquatic weed control, potatoes, asparagus,

strawberries, blueberries, grapes, cranberries, and citrus.

This summary will present exposure estimates and hazard determinations associated with 2,4-D

and its various chemical forms. In addition, risks of concern, as determined in the environmental

assessment, will be identified and characterized. More detailed information associated with the

potential environmental risk from the use of 2,4-D can be found in the Environmental Fate and

Effects Division’s Risk Assessment for the Reregistration Eligibility Document for 2,4-

Dichlorphenoxyacetic Acid, (2,4-D), dated October 28, 2004. The complete environmental risk

assessment is not included in this RED, but may be accessed in the OPP Public Docket (OPP-2004-

0167) and on the Agency’s website at http://www.epa.gov/pesticides/reregistration/status.htm.

1. Environmental Exposure

a. Environmental Fate and Transport

The environmental fate database is sufficient to characterize the environmental exposure

associated with 2,4-D use. However, there are some studies that will be required as a result of the

reregistration process. An aerobic aquatic metabolism study for 2,4-D BEE in acidic aquatic

environments is required, along with several other dissipation studies. See section V.A.1 of this

reregistration eligibility decision (RED) document for a complete list of all required studies. EPA

intends to issue a DCI as part of this RED to require submission of additional data to address areas of

uncertainty. These data are expected to confirm the conclusions of this environmental risk

assessment.
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Database

A complete database has been assembled for 2,4-D acid. The dissipation of 2,4-D appears to be

dependent on oxidative microbial-mediated mineralization, photodegradation in water, and leaching. 

2,4-D is stable to abiotic hydrolysis. Photodegradation of 2,4-D was observed [half life (t1/2) =12.9

calendar days or 7.57 days of constant light] in pH 5 buffer solution. However, the 2,4-D

photodegradation half-life on soil was 68 days. 

Degradation Summary

The degradation of 2,4-D was rapid (t1/2= 6.2 days ) in aerobic mineral soils. The half-life of

2,4-D in aerobic aquatic environments was 15 days. 2,4-D was moderately persistent to persistent

(t1/2 = 41 to 333 days) in anaerobic aquatic laboratory studies. 

Several degradates were detected in the laboratory fate studies reviewed. The degradates

detected were 1,2,4-benzenetriol, 2,4-DCP, 2,4-DCA, chlorohydroquinone (CHQ), 4-chlorophenol,

volatile organics, bound residues, and carbon dioxide. For a complete listing of 2,4-D degradates for

each route of degradation, please see the environmental risk assessment. No degradates were

considered for further analysis in water or the terrestrial ecological assessment. 

Mobility

2,4-D has a low binding affinity (Kad < 3 and Kde < 1) in mineral soils and sediment. The

mobility of 2,4-D in supplemental soil thin layer chromatography (TLC) studies was classified as

intermediately mobile (Rf=0.41) to very mobile (Rf=1.00) in "sieved" mineral soils. Aged

radiolabeled residues of 2,4-D appeared to be immobile in supplemental soil column studies. 2,4-D

was studied in sandy loam, sand, silty clay loam and loam soil. Freundlich Kads values were 0.17 for

the sandy loam soil, 0.36 for the sand soil, 0.52 for the silty clay loam soil, and 0.28 for the loam soil. 

Corresponding Koc values were 70, 76, 59 and 117 mL/g. 

Bridging Strategy

The 1988 2,4-D Registration Standard proposed an environmental fate strategy for bridging the

degradation of 2,4-D esters and 2,4-D amine salts to 2,4-D acid. The bridging provides information

on the dissociation of 2,4-D amine salts and hydrolysis of 2,4-D esters is included in the ecological

risk assessment. The bridging data indicate esters of 2,4-D are rapidly hydrolyzed in alkaline aquatic

environments, soil/water slurries, and moist soils. The 2,4-D amine salts have been shown to

dissociate rapidly in water. However, 2,4-D esters may persist under sterile acidic aquatic conditions

and on dry soil. These bridging data indicate under most environmental conditions 2,4-D esters and

2,4-D amines will degrade rapidly to form 2,4-D acid.

2,4-D Amine Salts

Additional data submitted subsequent to establishment of the environmental fate bridging

strategy generally support the strategy for the amine salts. Direct evidence of the stability of 2,4-D

amine salts in soil and aquatic environments is difficult due to the lack of analytical methods. Based

on maximum application rates for 2,4-D amine salts (at 4 lbs ae/A), 2,4-D amine salts are expected to

fully dissociate in soil environments because their theoretical concentrations in soil solution does not

exceed water solubilities. Additionally, dissociation studies indicate the time for complete
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dissociation is rapid (less than 3 minutes). Although the analytical methods in the field studies for

2,4-D DMAS were not capable of separating and identifying 2,4-D DMAS from 2,4-D acid, the most

conservative half-lives of 2,4-D DMAS would be equivalent to the 2,4-D acid half-lives in field

studies. Half-lives of 2,4-D in 2,4-DMAS field studies ranged from 1.1 days to 30.5 days with a

median half-life of 5.6 days. 

2,4-D Esters

The conversion of 2,4-D esters to the acid and an associated alcohol moiety is more difficult to

generalize. Unlike the physical dissociation mechanism of 2,4-D amine salts, the de-esterification of

2,4-D esters is dependent on abiotic and microbial-mediated processes. Any environmental variable

influencing microbial populations or microbial activity could theoretically influence the persistence of

the 2,4-D ester. Soil properties including clay mineralogy, organic carbon content, temperature, and

moisture content are known to influence hydrolysis rates (Wolfe, et al, 1989 and Wolfe, 1990).

Registrant-sponsored research indicates the 2,4-D esters (ethylhexyl, isopropyl, butoxyethyl)

degrade rapidly (half life less than 24 hours) in soil slurries, aerobic aquatic environments, and

anaerobic, acidic aquatic environments. In terrestrial field dissipation studies for 2,4-D EHE, the

half-lives for 2,4-D EHE ranged from 1 to 14 days with median half-life of 2.9 days. 2,4-D BEE,

applied as a granule formulation, degraded rapidly in the water column in aquatic field dissipation

studies under alkaline conditions. However, the 2,4-D BEE residues were detected in sediment

samples from Day 0 (immediately posttreatment) to 186 days posttreatment. It is unclear whether

2,4-D BEE persistence in sediment is due to the slow release of the granule formulation or to slow deesterification of sediment bound 2,4-D BEE. Available open-literature and registrant sponsored

laboratory data would suggest slow granule dissolution prolonged the persistence of 2,4-D BEE. In

forest dissipation studies, the 2,4-D EHE ester degraded slowly on foliage and in leaf litter. 

Persistance of 2,4-D Amine Salts and 2,4-D Esters

The weight of evidence from open-literature and registrant sponsored data indicates that 2,4-D

amine salts and 2,4-D esters are not persistent under most environmental conditions including those

associated with most sustainable agricultural conditions. 2,4-D amine salt dissociation is expected to

be instantaneous (< 3 minutes) under most environmental conditions. Although the available data on

de-esterification of 2,4-D ester may not support instantaneous conversion from the 2,4-D ester to 2,4-

D acid under all conditions, it does show 2,4-D esters in normal agriculture soil and natural water

conditions are short lived compounds (< 2.9 days). Under these conditions, the environmental

exposure from 2,4-D esters and 2,4-D amines is expected to be minimal in both terrestrial and aquatic

environments.

b. Aquatic Organism Exposure

For exposure to aquatic fish and invertebrates, EPA considers surface water exposure only,

since most aquatic organisms are not found in ground water. Surface water models are used to

estimate exposure to freshwater aquatic animals. Unlike the drinking water assessment described in

the human health risk assessment section of this document, the ecological water resource assessment

does not include the Index Reservoir (IR) and Percent-Crop Area (PCA) factor refinements. The IR
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and PCA factors represent a drinking water reservoir, not the variety of aquatic habitats, such as

ponds adjacent to treated fields, relevant to a risk assessment for aquatic animals. Therefore, the EEC

values used to assess exposure to aquatic animals are not the same as the values used to assess human

dietary exposure from drinking water sources.

1) Exposure to 2,4-D Acid in Surface Water

The aquatic exposure assessment for 2,4-D has relied on a combination of monitoring data and

modeling. Both Tier I (SCIGROW and screening level models for aquatic uses) and Tier II

(PRZM/EXAMS) models have been used to estimate exposure to 2,4-D and its various chemical

forms in a variety of exposure scenarios. Concentrations used for ecological assessment are 62.8 ug

ae/L for peak, 55.1 ug ae/L for the 21-day average concentration, and 45.4 ug ae/L for the 60-day

average. The predicted 2,4-D concentrations in surface water are slightly higher than reported

monitoring data. The modeling predictions are expected to indicate upper bound concentration

ranges for 2,4-D. Model input and output files for the ecological assessment may be found in the

ecological risk assessment for 2,4-D.

2) Surface Water Modeling of 2,4-D Esters

 The Agency’s strategy for bridging the fate data requirements for the ester and amine salt forms

of 2,4-D to the acid form was supported by laboratory data which indicated rapid conversion of the

amine and ester forms of 2,4-D to the acid form. However, 2,4-D esters may persist under acidic

aquatic conditions. In order to account for the potential impact of the spray application of 2,4-D

esters to aquatic environments, and to account for runoff during the time in which 2,4-D EHE may

remain in the field, the Agency conducted additional modeling with PRZM/EXAMS to assess the

potential for aquatic organisms to be exposed to 2,4-D EHE through spray drift or runoff. The peak

(acute) estimated environmental concentrations (EECs) for the 2,4-D esters were estimated for each

scenario and range from 0.6 ug ae/L (CA citrus) to 7.4 ug ae/L (NC pasture). A chronic EEC was not

provided in this scenario because the hydrolysis soil slurry data indicate that dissipation in a nonsterile water body will occur at all pHs and therefore long-term exposures are unlikely.

3) Modeling of Direct Application of 2,4-D for Control of Aquatic Weeds

Because there are no aquatic herbicide model scenarios, a first approximation of an aquatic

ecological EEC was predicted assuming direct application to the standard pond. For this assessment,

the Agency developed a simple spreadsheet model that incorporates degradation based on an

acceptable aerobic aquatic metabolism study for the EFED standard pond with no flow. In this

model, the 21-day average and 60-day average concentrations were calculated assuming first-order

dissipation from aerobic aquatic degradation, but does not assume dissipation.

The interpretation of the label for aquatic weed control is that the target rate for 2,4-D amine

(2,4-D DMAS) and ester (2,4-D BEE) use is based on concentration and not application rate. In

order to account for this scenario it was assumed that 2,4-D would be applied at a rate to meet the

target concentration of 4000 ug/l. This assumption would be applicable across all water bodies since
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the target rate is based on a rate per acre foot of water (10.8 lbs ae/acre-foot) and would be

independent of water body geometry/volume. This scenario included the assumption of uniform

application across the entire water body; however, this application scenario will over-predict actual

concentrations because 2,4-D is not applied to more than 50% of a water body in a single treatment. 

Treating more than 50% of a water body will result in oxygen depletion due to decaying plant

material. Typically, 2,4-D is applied to control aquatic weeds in littoral zones that make up less than

50% of the water body. Modeling the 2,4-D concentration that results when 100% of the water body

is treated predicts direct water application of 2,4-D will yield surface water concentrations of 2,4-D

concentrations in the EFED standard pond of 4000 ug ae/L for peak, 3417 ug ae/L for the 21-day

average, and 2610 ug ae/L for the 60-day average. Actual concentrations are expected to be less

given the conservative treatment area assumption as described above, and the likely effects of

dispersion on 2,4-D concentrations. 

EFED evaluated the potential for exposure to 2,4-D BEE using a similar approach. Modeling

predicts direct water application of 2,4-D BEE will yield surface water concentrations of 2,4-D BEE

concentrations in the EFED standard pond of 624 ug/L for peak (24 hour average), 30 ug/L for the

21-day average, and 10 ug/L for the 60-day average. 

4) Modeling of 2,4-D Use on Rice

Finally, the use of 2,4-D on rice was evaluated using a screening level model. 2,4-D is

registered for use in rice paddies for the acid and amine salt forms of 2,4-D (esters are not registered

for rice use) with a maximum seasonal application rate of 1.5 pounds ae per acre. Modeling of this

use rate results in an estimated acute 2,4-D concentration in the rice paddy of 1431 ug ae/L. This

value is expected to represent upper percentile concentrations for edge of paddy concentrations

because of the lack of consideration for degradation, dilution and dispersion. EFED conducted a

preliminary evaluation of the effect of degradation and holding times on EECs for the use of 2,4-D on

rice. As with the previous rice model, this refined model provides a single EEC which represents

both an acute and chronic exposure and is an approximation of the EEC at the point of release into a

receiving water body. Modeling with all three scenarios predict initial concentrations in the paddy

water between 678 ug ae/L (California) and 762 ug ae/L (Louisiana) and decreasing concentrations

with holding times based on degradation due to aerobic aquatic metabolism. 

c. Terrestrial Organism Exposure

The Agency assessed exposure to terrestrial organisms by first predicting the amount of 2,4-D

residues found on animal food items and then by determining the amount of pesticide consumed by

using information on typical food consumption by various species of birds and mammals. The

amount of residues on animal feed items are based on the Fletcher nomogram (a model developed by

Fletcher, Hoerger, Kenaga, et al.)1

 and the current maximum application rate as stated in the Master

Label for 2,4-D. For terrestrial uses of 2,4-D, the Master Label allows a maximum single application

of 4 lbs ae/A and up to two 2 lbs ae/A applications per season for a total seasonal maximum rate of 4
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lbs ae/A. Therefore, for terrestrial uses, EPA modeled the maximum and mean residues of 2,4-D in

various food items immediately after the 4 lb lbs ae/A application. The Agency assumed no dilution

due to the growth of the plants or degradation of 2,4-D. EPA’s estimates of 2,4-D residues on various

wild animal food items are summarized in Table 26. EPA used these EECs and standard food

consumption values to estimate dietary exposure levels for 2,4-D to birds and mammals.

Table 26. Estimated Environmental Concentrations on Avian and Mammalian Food Items

(ppm) Following a Single Application at 1 lb ae/A

Food Items EEC (ppm)

Predicted Maximum Residue1

EEC (ppm)

Predicted Mean Residue1

Short grass 240 85

Tall grass 110 36

Broadleaf/forage plants and small

insects

135 45 

Fruits, pods, seeds, and large insects 15 7

1

 Predicted maximum and mean residues are for a 1 lb ae/a application rate and are based on Hoerger and Kenaga (1972) as modified

by Fletcher et al. (1994).

1) Birds and Mammals

The Agency expects exposure to birds and mammals from residues of 2,4-D on food items. 

Exposure is probable because 2,4-D is applied in many different environments that provide habitats

rich in food sources attractive to various avian and mammalian species.

a) Exposure to Nongranular (Liquid) Formulations

Toxicant concentrations on food items following multiple applications are predicted based on a

first-order residue decline using the Agency's FATE5 model. The FATE5 model allows

determination of residue dissipation over time by incorporating degradation half-life. Predicted

maximum and mean EECs resulting from multiple applications are calculated by taking into account

the maximum or mean initial EEC from the first application, the total number of applications, the time

interval between applications, and a first-order foliar degradation rate of 8.8 days. 

b) Exposure to Granular Formulations

Birds and small mammals may be exposed to granular formulations through ingestion of

granules. The number of lethal doses (LD50) that are available within one square foot immediately

after application (LD50/ft2

) is used as the risk quotient (RQ) for granular products. RQs are calculated

for three separate weight classes of birds (1000 g, 180 g, and 20 g) and mammals (15 g, 35 g, and

1000 g, 35 g, and 15 g).

2) Non-target Terrestrial Plants
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Due to the differences in the solubilities of the acid and amine salts when compared to the

solubilities of the esters, risks for these two groups were calculated separately for the non-target

terrestrial plant risk assessment. The terrestrial plant toxicity data for the 2,4-D acid and amine salts

were bridged as one group, while that of the esters were bridged as another group.

Terrestrial plants inhabiting dry and semi-aquatic areas may be exposed to pesticides from

runoff, spray drift or volatilization. EPA’s runoff exposure estimate assumes a 1-in-10 year rain event

and is based on a pesticide's water solubility and the amount of pesticide present on the soil surface

and its top one inch, characterized as "sheet runoff" (one treated acre to an adjacent acre) for dry

areas, characterized as "channelized runoff" (10 treated acres to a distant low-lying acre) for semiaquatic areas, and is based on percent runoff values of 0.01, 0.02, and 0.05 for water solubility of <10

ppm, 10-100 ppm, and >100 ppm, respectively. The modeled runoff exposure estimates likely overestimate actual exposures from runoff, given the conservative 1-in-10 year rain event assumption, and

also given that farming practices, intended to minimize soil loss from runoff, are not taken into

account.

Spray drift exposure from ground and overhead chemigation applications is assumed to be 1%

of the application rate. Spray drift from aerial, airblast, and forced-air applications is assumed to be

5% of the application rate with an application efficiency (i.e., the amount that lands on the target area)

of 60%. The effects of multiple applications are addressed by summing the application rates from

individual applications. 

Applications of granular formulations may pose risks to terrestrial plants inhabiting dry and

semi-aquatic areas. Exposure is assumed to be from runoff only, and drift is assumed not to occur

with granular applications of pesticides. Therefore, the Agency's runoff scenario is essentially the

same as that used in the non-granular scenario described above, with the exception that the drift

component is removed. 

The EECs for the acid and amine salts as well as the esters to dry and semi-aquatic areas are

tabulated in Appendix F of the 2,4-D ecological risk assessment for single applications to the targeted

use sites. The percent runoff value based on water solubility is assumed to be 5% for the acid and

amines and 1% for the esters.

2. Environmental Effects (Toxicity)

a. Toxicity to Aquatic Organisms

Freshwater and Estuarine/Marine Fish

The available acute toxicity data on 2,4-D indicate that the acid and amine salts are practically

non-toxic to freshwater or marine fish. The esters are highly to slightly toxic to marine or freshwater

fish. Toxicities for the acid and amine salts range from a LC50 of >80.24 to 2244 milligrams acid

equivalent per liter (mg ae/L). The ester toxicities range from a LC50 of >0.1564 to 14.5 mg ae/L.
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Chronic toxicity, based on length and larval survival from the early life stage studies, range

from a NOEC of 14.2 to 63.4 mg ae/L for 2,4-D acid, 2,4-D DEA and 2,4-D DMAS. The NOEC

based on larval fish survival for the fish full life cycle studies ranged from 0.0555 to 0.0792 mg ae/L

for 2,4-D BEE and 2,4-D EHE. 

Amphibians

Although not currently required by the Agency, freshwater amphibian studies were conducted

on frog tadpoles (Rana pipiens). Tests were conducted using the ASTM (American Society for

Testing and Materials) Standard E729-88a. Tests indicate that 2,4-D acid, 2,4-D DMA, and 2,4-D

EHE are practically non-toxic to tadpoles. 

Freshwater and Estuarine/Marine Invertebrates

Acute toxicity of 2,4-D acid and amine salts to freshwater aquatic invertebrates ranges from a

LC50 of 25 to 642.8 mg ae/L (slightly toxic to practically non-toxic). The freshwater toxicities of the

esters range from 2.2 mg ae/L for the 2,4-D IPE to 11.88 mg ae/L for the 2,4-D EHE (moderately

toxic to slightly toxic). Acute toxicity of 2,4-D acid and amine salts to marine invertebrates range

from an LC50 of 49.6 for 2,4-D IPA to 830 mg ae/L for 2,4-D DMA (slightly toxic to practically nontoxic). The marine invertebrate LC50 s range from >0.092 to >66 mg ae/L for the 2,4-D esters (highly

toxic to practically non-toxic). These toxicities indicate that the esters are more toxic than the acid and

amine salts. Although acute data are missing for some of the amine salts, these studies will not be

required because none of the RQs exceed the aquatic levels of concern for the acid amine salts.

Chronic toxicity tests for freshwater and estuarine/marine invertebrates were performed on 2,4-

D acid, 2,4-D DEA, 2,4-D DMAS, and 2,4-D BEE. The toxicity ranged from a NOEC of 16.05 mg

ae/l for 2,4-D DEA (survival and reproduction) and 79 mg ae/L for the 2,4-D acid (number of young). 

The chronic freshwater NOEC is 0.20 mg ae/L for the 2,4-D BEE (survival and reproduction). There

are no freshwater or marine chronic toxicity data for any of the other 2,4-D esters. 

Although an estuarine/marine invertebrate life-cycle toxicity test using the TGAI is required to

establish the toxicity of products containing the 2,4-D acid, salts, and amines, a chronic study will not

be required. The data from the freshwater invertebrate studies will be bridged to the estuarine/marine

invertebrates for the 2,4-D acid and amine salts. The RQs for the freshwater chronic studies were

well below the levels of concern, and the chronic risk for estuarine/marine invertebrates would be

expected to be low. However, there is a risk concern for for estuarine/marine invertebrates for the

2,4-D esters. A chronic study will be required for 2,4-D BEE to reduce the uncertainty to

estuarine/marine invertebrates.

Aquatic Plants

The vascular plant EC50 toxicity data for the acid and amine salts range from 0.29 mg ae/L for

2,4-D DEA to 1.28 mg ae/L for 2,4-D TIPA. The EC50 toxicity data for the more toxic esters range

from 0.33 mg ae/L for 2,4-D EHE to 0.3974 mg ae/L for 2,4-D BEE. The same trend is shown for the
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non-vascular plant EC50. The nonvascular plant EC50 toxicity data range for the acid and amine salts is

3.88 to 156.5 mg ae/L for 2,4-D DMA. The range for the esters is 0.066 mg ae/L for 2,4-D EHE to

19.8 mg ae/L for 2,4-D EHE. In addition, based on the data available, it appears that the vascular

plants are more than two orders of magnitude more sensitive than the non-vascular plants.

b. Toxicity to Terrestrial Organisms

The bird and mammal toxicity values of the 2,4-D acid, salts, amine salts, and esters were

pooled because the toxicity values were within one to two orders of magnitude for all the chemical

forms. 

Birds

Toxicity ranges for birds do not show distinct differences between the acid, salts, amine salts,

and esters, as indicated for aquatic animals. All studies have been conducted with the active

ingredient, and have been converted to the acid equivalent since use rates on the master label are

given in pounds acid equivalent per acre. 

2,4-D is classified as moderately toxic to practically non-toxic to birds on an acute oral basis,

since the oral LD50 ranges from 500 mg ai/kg (415 mg ae/kg) for 2,4-D DMAS to >1000 mg ae/kg for

the 2,4-D acid. 

The chronic NOEC of 962 ppm is based on the endpoints of eggs cracked and a decreased

number of eggs laid for the 2,4-D acid. There is no comparable study for the mallard duck and no

other avian chronic study was performed on any of the other active ingredients. 

Mammals

The Agency expects exposure to mammals from residues of 2,4-D on food items, since 2,4-D is

used in many different mammalian habitats, including pasture and rangeland, and turf lawns. 

Toxicity ranges for mammals do not show distinct differences between the acid, salts, amine salts,

and esters as indicated for aquatic animals. All studies have been conducted with the active

ingredient, and have been converted to the acid equivalent since all use rates on the master label are

given in pounds acid equivalent per acre. The rat LD50 ranged from 579 to 1300 mg ae/kg.

Mammalian chronic toxicity values are from rat and rabbit developmental toxicity studies for

the 2,4-D acid and all amine salts, and esters. In addition, the 2-generation rat study is also available

for the 2,4-D acid. The NOAEL in the rat chronic toxicity study was 5 mg/kg/day, with a LOAEL of

75 mg/kg/day based on decreased body-weight gain and alterations in hematology. The NOAEL in

the rabbit developmental toxicity study was 30 mg/kg/day, and the LOAEL was 90 mg/kg/day based

on clinical signs, loss of righting reflex, and abortions. 
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Non-Target Insects

Available data from a honey bee acute toxicity study indicated that technical 2,4-D is practically

non-toxic to the honey bee. The LD50 in the honey bee acute toxicity study is greater than 10

micrograms per bee; see MRID 445173-04 for 2,4-D DMA and MRID 445173-01 for 2,4-D EHE. 

Minimal risk is expected to non-target insects from 2,4-D use. 

Terrestrial Plants

The terrestrial plant runoff exposure scenario is based on the solubility of the 2,4-D compound. 

The water solubilities differ greatly between 2,4-D esters and 2,4-D acid and amine salts. The

terrestrial plant toxicity values for 2,4-D acid and amine salts is summarized in Table 27, and have

been listed as the acid equivalent. The sensitivity ranges for the monocot and dicot species are listed

for the seedling emergence and vegetative vigor studies.

Table 27. Terrestrial Plant Toxicity Summary for 2,4-D Acid and amine salts

Study Type Most sensitive Crop /

Active Ingredient

EC25 / NOEC 

(lb ae/A)

Seedling Emergence Monocot Sorghum / 2,4-D DMAS 0.026 / 0.015

Dicot Mustard /2,4-D DEA 0.045 / <0.045

Vegetative Vigor Monocot Onion / 2,4-D Acid <0.0075 / <0.0075

Dicot Tomato / 2,4-D DEA 0.003 / 0.002

The terrestrial plant toxicity for the 2,4-D esters is summarized in Table 28. The sensitivity

ranges for the monocot and dicot species are listed for the seedling emergence and vegetative vigor

studies.

Table 28. Terrestrial Plant Toxicity Summary for 2,4-D Esters

Study Type Most sensitive Crop /

Active Ingredient

EC25 / NOEC 

(lb ae/A)

Seedling Emergence Monocot Onion / 2,4-D IPE 0.01 / 0.005628

Dicot Lettuce / 2,4-D IPE 0.00081 / 0.00047

Vegetative Vigor Monocot Corn /2,4-D IPE 0.2016 / 0.0252

Dicot Lettuce / 2,4-D IPE 0.00126 / 0.006132

3. Ecological Risk Estimation (RQs)

The Agency’s ecological risk assessment compares toxicity endpoints from ecological toxicity

studies to estimated environmental concentrations (EECs) based on environmental fate characteristics

and pesticide use data. To evaluate the potential risk to non-target organisms from the use of 2,4-D
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products, the Agency calculates a Risk Quotient (RQ), which is the ratio of the EEC to the most

sensitive toxicity endpoint values. These RQ values are then compared to the Agency’s levels of

concern (LOCs), given in Table 29, which indicate whether a pesticide, when used as directed, has

the potential to cause adverse effects on non-target organisms. When the RQ exceeds the LOC for a

particular category (e.g., endangered species), the Agency presumes a risk of concern to that category. 

These risks of concern may be addressed by further refinements of the risk assessment or by

mitigation. Use, toxicity, fate, exposure, and incidents are considered when characterizing the risk,

as well as the levels of uncertainty in the assessment. 

Table 29. EPA’s Levels of Concern and Associated Risk Presumptions.

Risk Presumption

LOC

terrestrial

animals

LOC 

aquatic

animals

LOC Plants

Acute Risk - there is potential for acute risk; regulatory action may be

warranted in addition to restricted use classification.

0.5 0.5 1

Acute Restricted Use - there is potential for acute risk, but may be

mitigated through restricted use classification.

0.2 0.1 N/A

Acute Endangered Species - endangered species may be adversely

affected; regulatory action may be warranted.

0.1 0.05 1

Chronic Risk - there is potential for chronic risk; regulatory action

may be warranted.

1 1 N/A

For a more detailed explanation of the ecological risks posed by the use of 2,4-D, refer to

Environmental Fate and Effects Division’s Risk Assessment for the Reregistration Eligibility

Document for 2,4- Dichlorophenoxyacetic Acid (2,4-D), dated October 28, 2004.

a. Risk to Aquatic Organisms

The RQs for aquatic organisms are presented in detail in Appendix F of the ecological risk

assessment for 2,4-D. 

1) Fish and Aquatic Invertebrates

There were no acute or chronic Level of Concern (LOC) exceedances for aquatic organisms

through use of 2,4-D acid and amine salts due to runoff/drift from use on terrestrial sites, no acute

LOC exceedances for aquatic organisms due to drift-only of 2,4-D esters to water bodies from use on

terrestrial sites, and, there were no acute LOC exceedances for aquatic organisms due to the

runoff/drift of 2,4-D esters to water bodies from use on terrestrial sites. Chronic concerns were not

evaluated for terrestrial uses of 2,4-D esters.

Estimated risk quotients (RQs) from use of 2,4-D acid and amine salts in aquatic weed control

through direct subsurface application to water bodies exceed the restricted use LOCs for freshwater
Page 64 of 304

invertebrates. There are no chronic LOC exceedances for this use. Estimated RQs for use of 2,4-D

BEE in weed control through direct subsurface application to water bodies exceed the acute risk LOC

for freshwater fish and invertebrates and chronic risk LOC for freshwater and estuarine fish and

freshwater invertebrates when compared on an acid equivalent basis. 

Additional characterization of the potential risk associated with the direct application of 2,4-D

for aquatic weed control was completed by back-calculating the target concentration needed to reduce

EECs below LOCs. This type of consideration provides context to the characterization of potential

risk and indicates that for all 2,4-D chemical forms target concentration reduction of up to 10-fold still

exceeds all LOCs for aquatic organisms. 

While noting the potential risks identified above, it is important to note the benefits gained

through the direct application of 2,4-D to aquatic bodies, for the control of invasive species. The U.S

Army Corps of Engineers (USACE), among others, has identified 2,4-D as an important tool for

protecting the nation's waters from the invasion and establishment of some of the world's worst

species of exotic nuisance vegetation. 2,4-D has a reputation as a selective and economical means to

remove invasive plants, enhance the growth and recovery of desirable native vegetation, restore water

quality, reduce sedimentation rates in reservoirs, and improve fish and wildlife habitat. 2,4-D

products are used to control invasive weeds, such as Eurasian watermilfoil (Myriophyllum spicatum)

in the northern tier states and water hyacinth (Eichhornia crassipes) in the Gulf Coast states. Effective

control of these plants can benefit public health with respect to reducing levels of mosquito habitat. In

addition, according to USACE, no other product (or alternative technique) can control these plants in

a more cost-effective manner (K. Getsinger, USACE, Public Comment; Docket ID# OPP-2004-0167-

0053).

Estimated RQs for use of 2,4-D acid and amine salts in rice paddies exceed the acute

endangered species LOCs for freshwater invertebrates. The rice model used to predict these EECs is

a screening level model which predicts concentration in tailwater at the point of release from the

paddy. It is anticipated that once released, the concentration will be reduced and subsequently is

expected to decrease away from the point of release. Additional characterization was conducted by

considering average application rates (average rates are presented in the quantitative usage analysis

dated August 9, 2001 prepared by the Biological and Economic Affairs Division of EPA/OPP) versus

maximum label rates and assuming a proportional reduction in EECs. Consideration of average

application rates results in EECs below the endangered species LOC.

2) Aquatic Plants

For non-target, aquatic plants, estimated RQs resulting from the runoff/drift of 2,4-D acid and

amine salts from use on terrestrial crops exceed the aquatic vascular plant endangered species LOCs

for use of 2,4-D acid and amine salts on pasture and apples. Consideration of average application

rates and assuming a proportional reduction in EECs results in RQs below the endangered species

LOC. Likewise, there are no LOC exceedances from the drift of the ester forms to aquatic water

bodies or from the runoff of the ester forms to water bodies from use on terrestrial sites. 
Page 65 of 304

Estimated RQs for the scenario of direct application to water for aquatic weed control for 2,4-D

acid and amine salts indicate acute and endangered species LOC exceedances for aquatic vascular

plants and acute LOC exceedances for non-vascular plants, while estimated RQs for the use of 2,4-D

BEE for direct application to water to control aquatic weeds exceed all LOCs for vascular and one

acute LOC exceedance for non-vascular plants. Risk to endangered non-vascular plants is not

evaluated because at this time there are no listed endangered nonvascular plant species. Additional

characterization of potential risk for the direct application of 2,4-D for aquatic weed control was

completed by back-calculating the target concentration needed to reduce the RQs below LOCs. This

type of consideration provides context to the characterization of potential risk and indicates that for all

2,4-D chemical forms target concentration reduction of up to 100-fold still exceeds all LOCs for

aquatic plants. 

While noting the potential risks identified above, it is important to note the benefits gained

through the direct application of 2,4-D to aquatic bodies, for the control of invasive species. The U.S

Army Corps of Engineers (USACE), among others, has identified 2,4-D as an important tool for

protecting the nation's waters from the invasion and establishment of some of the world's worst

species of exotic nuisance vegetation. 2,4-D has a reputation as a selective and economical means to

remove invasive plants, enhance the growth and recovery of desirable native vegetation, restore water

quality, reduce sedimentation rates in reservoirs, and improve fish and wildlife habitat. 2,4-D

products are used to control invasive weeds, such as Eurasian watermilfoil (Myriophyllum spicatum)

in the northern tier states and water hyacinth (Eichhornia crassipes) in the Gulf Coast states. Effective

control of these plants can benefit public health with respect to reducing levels of mosquito habitat. In

addition, according to USACE, no other product (or alternative technique) can control these plants in

a more cost-effective manner (K. Getsinger, USACE, Public Comment; Docket ID# OPP-2004-0167-

0053).

Estimated RQs for use of 2,4-D acid and amine salts in rice paddies exceed the acute and

endangered species LOCs for aquatic vascular plants. Consideration of average application rates

results in RQs below the endangered species LOCs. 

b. Risk to Non-target Terrestrial Organisms

1) Birds

The RQs for birds are presented in detail in Appendix F of the ecological risk assessment for

2,4-D. Potential risks were evaluated for non-granular and granular formulations applied both as

banded and broadcast applications. 

EPA has relied on risk estimates from oral gavage studies on birds (LD50 of 415 mg ae/kg-bw )

to assess risk because no definitive endpoint was determined from dietary studies. Therefore, it is

likely that the risk estimates associated with the gavage studies overestimate the actual exposure of

birds in the field. For predicted maximum exposures when compared with oral gavage data there are

exceedances of acute LOCs for all use sites except potatoes and citrus for most small birds and some

medium birds. There are also exceedances of acute restricted use and endangered species LOCs for

medium and large birds feeding on short grass, tall grass, and broadleaf forage/small insects at all use

sites except potatoes and citrus. However, comparison with the lowest dietary LC50 of >5620 mg
Page 66 of 304

ae/kg-diet would result in no acute LOC exceedances. As noted previously, no definitive endpoint

was available from the avian acute dietary studies and, hence, risk was not evaluated using this

endpoint. 

The RQs are presented below in Table 30 for the avian risk due to 2,4-D residues on various

food items. 

Table 30. Avian Risk Quotient Summaries for Non-granular Spray Applications of 2,4-D acid,

amine salts and esters

Use Site (Acute &

Chronic Risk)

Scenario

Short Grass Tall Grass Broadleaf, forage,

small insects

Fruit, large insects,

Fallow areas and Crop Stubble; Turf (Golf courses, Residential Lawns, Grasses Grown for Seed, and Sod); Pastures,

Rangeland, Perennial Grassland; Sugarcane (2 lbs ae/A/app, 2 app., ground/aerial, 30 day interval)

Acute RQ Exceedance 0.1* - 1.91*** 0.04 - 0.88*** 0.04 - 0.78*** -

Non-Cropland (Fencerows, Hedgerows, Roadsides, Ditches, Rights-of-Way, Utility Power Lines, Railroads, Airports,

Industrial Sites, etc.); Forest Uses, Cranberry (4.0 lbs ae/A/app, 1 app., ground/aerial,)

Acute RQ Exceedance 0.18* - 3.5*** 0.07 - 1.6*** 0.07 - 1.43*** 0.01 - 0.15*

Fruit, Small Grains (Except Corn), Asparagus (1.4 to 2.0 lbs ae/A/app)

Acute RQ Exceedance 0.09 - 1.75*** 0.04 - 0.81*** 0.03 - 0.72*** -

Corn (1.5 lbs ae/A/app, 2 app., 7 day interval, ground or aerial)

Acute RQ Exceedance 0.1* - 2.07*** 0.04 - 0.81*** 0.03 - 0.72*** -

* indicates an exceedance of Endangered Species Level of Concern (LOC).

** indicates an exceedance of Acute Restricted Use LOC.

*** indicates an exceedance of Acute Risk LOC.

Chronic risk calculations resulted in RQ’s of 1.0 to 1.1 on birds which forage on short grass

when the application rate of 2,4-D ranges from 2.0 to 4.0 lb ae/A such as seen with rights-of-way,

cranberries or asparagus. The chronic risk LOC is 1.0.

Non-granular Banded Applications - According to the Master Label for 2,4-D, products that allow

for banded applications of sprays to row crops require all formulators to adjust the application rates

according to a formula provided. Many current labels do not advise applicators to adjust the

application rates, and the resulting treatment can be interpreted to concentrate the per acre application

rate into a narrow band. Birds, at least in theory, could be exposed to the higher concentration of

toxicant by foraging or wandering into the treated band. EPA/OPP evaluated the banded risk by

comparing the RQs from unadjusted band rates to those using the adjusted band rates to illustrate the

increased risk. OPP assumed a 6 inch band and 30 inch row space as a typical banded application. 

The RQs indicate that levels of concern are not exceeded for 1000 g birds for rates adjusted due to

band widths. LOCs are also not exceeded for these adjusted rates for potatoes for all weight classes

of birds. The unadjusted band width rate, however, exceeds LOCs for all weight classes of birds for

all uses with the exception of potatoes. 

Granular Broadcast Applications - Acute RQs for granular products are calculated for three separate
Page 67 of 304

weight classes of birds using the LD50/ft2: 1000 g (e.g., waterfowl), 180 g (e.g., upland gamebird), and

20 g (e.g., songbird). The acute RQs for broadcast applications of granular products are tabulated

below for the use sites from the 2,4-D Master Label which support granular formulations. 

Table 31: Avian Acute Risk Quotient Calculations for Granular Broadcast Applications

Bird Body Weight (g) Acute RQ 

(LD50 per ft2

) a

Non-Cropland (4.0 lbs ae/A/app, 1 app., ground/aerial,)

Aquatic areas (4.0 lb ae/A/app. 3 wks between apps)

Cranberry (4.0 lbs ae/A/app, 1 app., ground)

20 5.02***

180 0.55***

1000 0.1*

Turf (2.0 lbs ae/A/app, 2 app., ground/aerial, 30 day interval)

Aquatic areas - Ditchbank applications (2.0 lb ae/A/app., 2 app.,

ground)

20 2.5***

180 0.3**

1000 0.05

Aquatic areas - Surface application or subsurface injection (10.8

lb ae/acre-foot to an average pond depth of 5 feet)

20 13.55***

180 1.5***

1000 0.27**

a

 RQ = App. Rate (lbs ae) x 453,590 mg x Acre x 1 x 1000 g x Kg 

 Acre Lb 43,560 ft2 Animal weight (g) 1 kg LD50 mg

* indicates an exceedance of Endangered Species Level of Concern (LOC).

** indicates an exceedance of Acute Restricted Use LOC.

*** indicates an exceedance of Acute Risk LOC.

Granular Banded Applications - In addition to broadcast applications of granular formulations, a

number of labels instruct the applicators to apply unincorporated banded treatments of granular

products to crops. As explained for banded spray treatments above, many labels adjust application

rates according to band width and row spaces, but many others do not. If banded granular

applications were used at the same sites as banded spray applications, the risk would be similar.

2) Mammals

Acute LOCs for mammals feeding on plants and insects were exceeded when considering nongranular formulations, for all uses assessed for small and medium size mammals, except potatoes and

citrus. There were no exceedances for granivores. Banded applications result in exceedances of

acute LOCs at all use sites. 

Mammalian chronic RQs range from 0.05 to 200 and chronic LOCs were exceeded in all cases

with the exception of potatoes and citrus (large insects, seeds). Consideration of average application

rates results in EECs below the LOCs for non-granular, granular, or banded applications. However,

consideration of average application rates for non-granular, granular and banded applications did not

result in exposure below the chronic LOC. 
Page 68 of 304

Acute Exposure from Nongranular 2,4-D Products The acute RQs for broadcast applications of

nongranular products are tabulated for herbivores/insectivores and granivores in Appendix F of the

ecological risk assessment for 2,4-D. When the LD50 of 1072 mg ai/kg (579 mg ae/kg) is used for in

herbivore/insectivore RQ calculations, endangered species LOCs are exceeded at many sites for

mammals foraging on short and tall grass, broadleaf plants, and small insects. The RQs range from

1.72 for asparagus to < 0.01 for potatoes. There are no LOC exceedances for granivorous mammals. 

As described above for avian risk, in addition to broadcast spray, a number of labels instruct the

applicators to apply unincorporated banded treatments of sprays to row crops. Using the same

assumptions as described above for birds, the RQs for mammals are presented in Table 32. Again,

for purposes of comparison, the unadjusted rates that appear on many of the current labels have been

included. Using the mammalian LD50 of 579 mg ae/kg, acute levels of concern are exceeded at all

use sites and for 15, 35, and 1000 g mammals when banded rates are not adjusted. When the banded

rates are adjusted, LOCs are not exceeded for 1000 g mammals. The results of these calculations are

tabulated in Appendix F of the ecological risk assessment for 2,4-D.

Acute Exposure to Granular 2,4-D Products - Mammalian species also may be exposed to granular

pesticides by ingesting granules. The number of lethal doses (LD50) that are available within one

square foot immediately after application can be used as a RQ (LD50/ft2) for the various types of

exposure to pesticides. RQs are calculated for three separate weight classes of mammals: 15 g, 35 g,

and 1000 g. The LOCs are exceeded for all sites with the following exceptions: no LOCs are

exceeded for 1000 g mammals in turf, aquatic areas (ditchbanks and surface applications), or

cranberries. 

The acute RQs for broadcast applications of granular products are tabulated below for the use

sites from the master label which support granular formulations.

Table 32: Mammalian Acute Risk Quotient Calculations for Granular Broadcast Applications

Animal Body Weight (g) Acute RQ (LD50 per ft2) 1

Non-Cropland (4.0 lbs ae/A/app, 1 app., ground/aerial,)

Aquatic areas (4.0 lb ae/acre/app. 3 weeks between

applications)

Cranberry (4.0 lbs ae/A/app, 1 app., ground)

15 4.8 *** 

35 2.1 *** 

1000 0.1 * 

Turf (2.0 lbs ae/A/app, 2 app., ground/aerial, 30 day interval)

Aquatic areas - Ditchbank applications (2.0 lb ae/acre/app., 2

app., ground

15 2.4 *** 

35 1.0 *** 

1000 ??

Aquatic areas - Surface application or subsurface injection 

(10.8 lb ae/acre foot to an average pond depth of 5 feet)

15 12.9 ***

35 5.5 ***

1000 0.2 **

1

 RQ = App. Rate (lbs ae) x 453,590 mg x Acre x 1 x 1000 g x Kg 

 Acre Lb 43,560 ft2 Animal weight (g) 1 kg LD50 mg

* indicates an exceedence of Endangered Species Level of Concern (LOC).

** indicates an exceedence of Acute Restricted Use LOC.

*** indicates an exceedence of Acute Risk LOC.
Page 69 of 304

Chronic Exposure to Mammals - The chronic RQs for broadcast applications of nongranular

products are tabulated in Appendix F of the 2,4-D ecological risk assessment for all classes of

mammals. The parental toxicity NOAELs ranged from 5 mg/kg/day based on female body weight

gain and male renal tubule alteration for the 2,4-D acid. The FATE program was used to determine

the maximum and 56-day average residues that occur in a one year time period. The application rate,

minimum number of applications, and the interval between applications were determined from the

2,4-D Master Label and represent the highest single application rates. Levels of concern were

exceeded in all cases with the exception of potatoes and citrus (large insects, seeds) and RQs ranged

from 0.1 to 200. 

3) Non-Target Insects

The Agency currently does not quantify risks to terrestrial non-target insects. RQs are therefore

not calculated for these organisms. Since the test results from one of the salts (2,4-D DMAS) and

2,4-D EHE was practically non-toxic to honey bees (LD50 of >100 μg/bee), the potential for 2,4-D

and its salts and esters is predicted to pose minimal risk to pollinators and other beneficial insects. 

4) Non-target Terrestrial Plants

Acute LOCs for both non-endangered and endangered terrestrial plants were exceeded for nongranular and granular uses at many use sites. Consideration of average application rates did not result

in exposure below LOCs. 

RQs for terrestrial plants in dry and semi-aquatic areas are calculated for multiple and single

spray applications for endangered and non-endangered species. As mentioned above in the exposure

section, the runoff scenarios are based on solubility, and as a consequence, the environmental

concentrations must be calculated separately for the esters and the acid and amine salts. The

environmental concentrations for the esters were calculated separately at a percent runoff value of

0.01, while that of the acid and amine salts were calculated at a value of 0.05. A 60% efficiency

factor is also included for aerial applications. In addition, banded applications granular and nongranular formulations are also calculated. The detailed calculations for terrestrial plants are tabulated

in Appendix F of the ecological risk assessment.

Risk Quotient (RQ) Calculations - To calculate the RQs for non-endangered plants the EC25 value of

the most sensitive species in the seedling emergence study is compared to runoff and drift exposure to

determine the RQ (EEC/toxicity value). The EC25 value of the most sensitive species in the

vegetative vigor study is compared to the drift exposure to determine the acute RQ. RQs are

calculated for the most sensitive monocot and dicot species.

RQs for Endangered Plants - To calculate the RQs for endangered plants the NOEC or EC05 value of

the most sensitive species in the seedling emergence study is compared to runoff and drift exposure

(EEC/toxicity value). The NOEC or EC05 value of the most sensitive species in the vegetative vigor

study is compared to the drift exposure to determine the acute RQ. RQs are calculated for the most

sensitive monocot and dicot species. The RQ ranges for single and multiple applications are

summarized below for non-endangered and endangered plants for the acid and amine salts, and
Page 70 of 304

separately for the esters. 

• Single Spray Applications - Most use sites on the 2,4-D Master Label allow multiple

applications. However, the following use sites are labeled for maximum application rate for a

single application. 

Table 33. 2,4-D Use Sites With Maximum Labeling for a Single Application

Use Site Application Rate/Method

Non-crop 1, Forest Uses, Cranberry Ground & Aerial Applications (4.0 lbs ae/A/app.,)

Strawberry, Rice Ground & Aerial Applications (1.5 lbs ae/ac/app.)

Grapes Ground Applications (1.36 lbs ae/A/app.)

Sorghum, Soybean Ground and Aerial Applications (1.0 lbs ae/A/app.)

 Soybean Ground & Aerial Applications (1.0 lbs ae/A/app.)

Citrus Ground or Aerial Applications (0.1 lbs ae/A/app.)

1

 Woody plants in rights-of-way. Other non-crop sites may have up to 2 applications of 2 lbs each.

The detailed RQ calculations for single applications are tabulated in detail in Appendix F of the

ecological assessment for 2,4-D, and a summary is presented below.

Table 34. Terrestrial Plant Risk Quotients for Single Applications 

Chemical Group (acid / ester) Plant Group (non-endangered /

endangered)

Risk Quotient Range

2,4-D Acid and Amine Salt non-endangered 0.18 - 67

endangered 0.13 - 136

2,4-D Ester

non-endangered <0.01 - 543.21

endangered 0.04 - 936.17

Multiple spray applications - Most of the 2,4-D products on the 2,4-D Master Label allow second

applications at prescribed intervals ranging from 7 to 30 days with the exception of pome fruit which

allows a 75 day interval. The RQs for multiple applications follow a linear pattern for changes in

application rates, and since a maximum of two applications is allowed, the RQ doubles for these

applications. The detailed calculations are tabulated in detail in Appendix F of the 2,4-D ecological

risk assessment, and a summary is presented below.

Table 35. Terrestrial Plant Risk Quotients for Multiple Applications

Chemical Group (acid / ester) Plant Group (non-endangered /

endangered)

Risk Quotient Range

2,4-D Acid and Amine Salt non-endangered 0.19 - 157

endangered 0.19 - 272
Chemical Group (acid / ester) Plant Group (non-endangered /

endangered)

Risk Quotient Range

Page 71 of 304

2,4-D Ester

non-endangered 0.01 - 12

endangered 0.01 - 33

Banded Spray Applications - Banded spray applications are allowed on a number of labels and

instruct the applicators to apply unincorporated banded treatments of sprays to row crops. Many

labels adjust application rates according to band width and row spaces, but others do not. For the

labels which do not adjust the application rates, the treatments could be more concentrated in the

bands. Since non-target plants do not migrate from treated to untreated bands as is the case with birds

and mammals, exposure to plants is characterized as "sheet runoff" (one treated acre to an adjacent

acre) for dry areas and "channelized runoff" (10 treated acres to a distant low-lying acre) for semiaquatic areas. Therefore, the higher per acre rates in the concentrated bands do not affect the

exposure to non-target plants when label rates are not adjusted.

The 2,4-D Task Force proposal to require all formulators to adjust the application rates for

banded applications will reduce the exposure to non-target plants. If we assume use of the same 6

inch band and 30 inch row space that we used for the analysis of birds and mammals, the per acre

banded application rate would be reduced by 1/5 of the broadcast application rate. The RQs are

detailed in Appendix F of the ecological risk assessment for 2,4-D, and summarized for multiple and

single applications in the following table.

Table 36. Non-target Plant Risk Quotient Summary of Adjusted Band Applications to Selected

Row Crops.

Chemical Group (acid /

ester)

Plant Group (nonendangered /

endangered)

Risk Quotient Range

(Single Applications)

Risk Quotient Range

(Multiple Applications)

2,4-D Acid and Amine Salt non-endangered 0.02 - 60 0.04 - 120

endangered 0.02 - 439 0.04 - 878

2,4-D Ester

non-endangered <0.01 - 27 <0.01 - 54

endangered <0.01 - 47 <0.01 - 94

Granular Applications - The only currently approved granular applications which are currently

allowed on the master label are on grass grown for seed or sod, turf, cranberries, non-crop land, and

aquatic weed control sites. The non-target terrestrial plant RQ summaries for the acid and amine salts

for the esters are presented below. Detailed RQs are presented in Appendix F of the ecological risk

assessment for 2,4-D.
Page 72 of 304

Table 37. Non-target Plant Risk Quotient Summary of Granular Applications to Selected Uses.

Chemical Group (acid /

ester)

Plant Group (non-endangered /

endangered)

Risk Quotient Range

(Single Applications)

Risk Quotient

Range (Multiple

Applications)1

2,4-D Acid and Amine Salt

non-endangered 2.2 - 77 4.4 - 154

endangered 2.2 - 133 4.4 - 266

2,4-D Ester

non-endangered 2.0- 494 4.0 - 987.62

endangered 3.57 - 851 7.14 - 1702.12

1

 Turf is only site for multiple applications of granular products.

4. Ecological Incidents

Aquatic Incidents

The EFED Ecological Incident Information System (EIIS) database reports pesticide incidents

that have been voluntarily submitted to EPA by state agencies. The report assigns a certainty index of

0 (unrelated), 1 (unlikely), 2 (possible) 3 (probable) or 4 (highly probable) to each incident. In

addition, a judgement of registered use, accidental misuse, intentional misuse, or undetermined is

assigned. There were 227 incidents reported for 2,4-D, and 24 of these incidents were reported as

aquatic incidents under the 2,4-D acid only.

The two “highly probable” registered use incidents occurred when 2,4-D was applied to corn

and a railroad right-of-way. The corn application resulted in bluegill and largemouth bass mortalities

in Missouri, while the right-of-way application resulted in a kill of 23,000 (presumably) fish. 

The corn incident affected bluegill, catfish, crappie, fox squirrel, greengill, largemouth bass,

silver minnow, smallmouth bass, sunfish and watersnake. This incident was determined to be “highly

probable” and was not listed as a misuse, however, no residue analysis was obtained. Another

incident was recorded as “possible” and the use was “undetermined.” The species affected included

bass, catfish, crappie, grass carp, and perch.

Results from these incidents should be regarded with caution since it is not clear exactly which

products or tank mixes might be involved. In addition, residue analysis was not available in almost

all instances.

Terrestrial Incidents

 There were 227 terrestrial incidents reported for 2,4-D, and 155 of these incidents were

reported as plant incidents under the acid form only. Two incidents were reported as both terrestrial

and aquatic.

Eighty-four incidents to plants were listed as registered uses and most were considered

“probable.” Crop damage was reported to have occurred on numerous crops, but most common nontarget plant damages occurred on grass and corn. However, most of these incidents resulted from

applications to lawns/turf and corn, respectively.

Results from the incident reports should be regarded with caution since it is not clear exactly

which products or tank mixes might be involved. In addition, residue analysis was not available in

almost all instances. 

5. Endangered Species Concerns
Page 73 of 304

The Agency has developed the Endangered Species Protection Program to identify pesticides

whose use may cause adverse impacts on endangered and threatened species, and to implement

mitigation measures that address these impacts. The Endangered Species Act requires federal

agencies to ensure that their actions are not likely to jeopardize listed species or adversely modify

designated critical habitat. To analyze the potential of registered pesticide uses to affect any

particular species, EPA puts basic toxicity and exposure data developed for REDs into context for

individual listed species and their locations by evaluating important ecological parameters, pesticide

use information, the geographic relationship between specific pesticide uses and species locations,

and biological requirements and behavioral aspects of the particular species. This analysis will take

into consideration any regulatory changes recommended in the RED that are being implemented at

this time. A determination that there is a likelihood of potential impact to a listed species may result

in limitations on use of the pesticide, other measures to mitigate any potential impact, or consultations

with the Fish and Wildlife Service and/or the National Marine Fisheries Service as necessary. 

The Endangered Species Protection Program as described in a Federal Register notice (54 FR

27984-28008, July 3, 1989) is currently being implemented on an interim basis. As part of the

interim program, the Agency has developed County Specific Pamphlets that articulate many of the

specific measures outlined in the Biological Opinions issued to date. The Pamphlets are available for

voluntary use by pesticide applicators on EPA’s website at www.epa.gov/espp. 

The preliminary risk assessment for endangered species indicates that 2,4-D exceeds the

endangered species LOCs for the following combinations of analyzed uses and species:

• Estimated risk quotients (RQs) from use of 2,4-D DMAS in weed control through direct

subsurface application to water bodies exceed the endangered species LOC for freshwater and

estuarine fish, and estuarine invertebrates. However, there are currently no endangered

estuarine/marine invertebrates.

• Estimated RQs from use of 2,4-D BEE in weed control through direct subsurface application to

water bodies exceed the endangered species LOC for freshwater fish and invertebrates and

estuarine fish. 

• Estimated RQs from use of 2,4-D acid and amine salts in rice paddies exceed endangered

species LOCs for freshwater invertebrates. The rice model used to predict these EECs is a

screening level model which predicts concentration in tailwater at the point of release from the

paddy. It is anticipated that once released, the concentration will be reduced and subsequently,

RQs will decrease. 

• The scenario of the direct application to water for weed control for the acid and amine salts

indicates a endangered species concern for aquatic vascular plants. Estimated RQs from use of

2,4-D BEE for direct application to water for weed control exceed all LOCs for both vascular

and non-vascular plants. Potential risk to endangered non-vascular plants is not evaluated

because at this time there are no listed endangered non-vascular plant species.

• Target acute RQs for birds and mammals were exceeded for endangered species risks for

multiple crops and multiple animal weights. Banded and granular applications result in higher

RQs at more use sites.

• Target acute LOCs for both non-endangered and endangered plants were exceeded for nongranular and granular for multiple uses, based on predicted EECs.
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In December 2004, EPA completed a refined assessment for 2,4-D's potential effects to 26

environmentally significant units (ESUs) of Pacific Salmonids (salmon and steelhead). That refined

assessment concluded that 2,4-D has "no effect" on these species when used according to label

directions on terrestrial sites. Further, that assessment concluded that use of 2,4-D on rice "may affect

but is not likely to adversely affect" 4 ESU's and will have "no effect" on 22 ESU's. That same

analysis concluded that use of 2,4-D "may affect" each of the 26 ESU's when used for aquatic weed

control purposes. As a result of that assessment, EPA is currently engaged in consultation with the

National Marine Fisheries Service regarding those scenarios that resulted in a determination that 2,4-

D "may affect but is not likely to adversely affect" the species, or "may affect" the species. 

The Agency’s level of concern for endangered and threatened freshwater fish and invertebrates,

estuarine invertebrates, birds, mammals, aquatic vascular plants, and terrestrial non-target plants is

exceeded for the use of 2,4-D. The Agency recognizes that there are no Federally listed

estuarine/marine invertebrates. The registrant must provide information on the proximity of Federally

listed freshwater vascular plants, birds, mammals, and non-target terrestrial plants (there are no listed

estuarine/marine invertebrates) to the 2,4-D use sites. This requirement may be satisfied in one of

three ways: 1) having membership in the FIFRA Endangered Species Task Force (Pesticide

Registration [PR] Notice 2000-2); 2) citing FIFRA Endangered Species Task Force data; or 3)

independently producing these data, provided the information is of sufficient quality to meet FIFRA

requirements. The information will be used by the OPP Endangered Species Protection Program to

develop recommendations to avoid adverse effects to listed species.

6. Risk Characterization

The Agency has considered available information on 2,4-D’s toxicity, use areas, usage, fate

properties, and application methods and formulations in characterizing ecological risks related to

normal use. Upon review and synthesis of this information, the Agency concludes use of 2,4-D for

aquatic weed control presents risk to aquatic organisms, while 2,4-D use on terrestrial sites presents

the greatest potential risks to small mammals, birds, and non-target terrestrial plants. 

a. Characterization of risk to aquatic organisms from direct aquatic

application

Whereas the maximum labeled target concentration for control of aquatic weeds is 4 ppm, the

typical target concentration is 2 ppm. Moreover, the risks to aquatic organisms were estimated based

on a 2,4-D application that resulted in a whole-reservoir concentration of 4 ppm. Treating 100% of

the water body would result in a large amount of decaying plant life, thereby creating an oxygendepleted environment that would most likely result in fish kills. To avoid that scenario, the 2,4-D

label advises the applicator to avoid treating more than 50% of a water body in a single application. 

In actual practice, aquatic weeds that 2,4-D controls tend to grow in littoral zones. As a result,

generally a maximum of 20-30% of a water body is treated in a single application. Applying the

typical rate of 2 ppm, and taking into account a typical maximum treated area of 30% would decrease

calculated RQs by approximately 6-fold. 

While noting the potential risks to aquatic organisms from the direct application of 2,4-D for the

control of aquatic weeds identified above, it is important to note the benefits gained through the direct

application of 2,4-D to aquatic bodies, for the control of invasive species. The U.S Army Corps of
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Engineers (USACE), among others, has identified 2,4-D as an important tool for protecting the

nation's waters from the invasion and establishment of some of the world's worst species of exotic

nuisance vegetation. 2,4-D has a reputation as a selective and economical means to remove invasive

plants, enhance the growth and recovery of desirable native vegetation, restore water quality, reduce

sedimentation rates in reservoirs, and improve fish and wildlife habitat. 2,4-D products are used to

control invasive weeds, such as Eurasian watermilfoil (Myriophyllum spicatum) in the northern tier

states and water hyacinth (Eichhornia crassipes) in the Gulf Coast states. Effective control of these

plants can benefit public health with respect to reducing levels of mosquito habitat. In addition,

according to USACE, no other product (or alternative technique) can control these plants in a more

cost-effective manner (K. Getsinger, USACE, Public Comment; Docket ID# OPP-2004-0167-0053).

b. Characterization of risk to mammals from terrestrial use

All of the calculated RQs for mammalian acute risk for the non-granular use of 2,4-D were

based on maximum labeled application rates. The QUA from BEAD (Quantitative Usage Analysis

for 2,4-D, Case Number: 0073, Date: 8-9-01, A. Halvorson) suggests that the average application

rates for many crops are considerably less than the modeled maximum application rates. For nongranular spray application mammalian acute concerns, the highest RQ was 1.72 for use on asparagus

for small mammals feeding on short grass based on a maximum application rate of 4 lbs ae/acre;

however, the average application rate was only 1.10 lbs ae/acre (BEAD QUA). If the modeled

application rate was reduced to the reported average application rate of 1.10 lbs ae/acre for asparagus,

the RQ would be 1.08 which is still above the acute LOC of 0.5. However, asparagus is

representative of a minor 2,4-D use, and risk to mammals from use of 2,4-D on asparagus would be

minimal, given that fact.

To add context to the acute mammalian assessment, the effect of assuming an average

application rate was determined. Major 2,4-D crops include pasture/rangeland, turf, wheat, corn, and

soybeans. For pasture/rangeland, the highest acute RQ was 0.86 for small mammals feeding on short

grass based on a maximum application rate of 4 lbs ae/acre. However, the average application rate

was only 0.62 lbs ae/acre (BEAD QUA). If the modeled application rate was reduced to 0.62 lbs

ae/acre for pasture/rangeland, the resulting RQ is 0.31 which is below the acute LOC, but above the

restricted use LOC of 0.2. Similar trends are noted for other major use sites.

Calculated chronic risks to mammals were greatest for small herbivores/insectivores. For 15 g

mammalian herbivores/insectivores, chronic RQs based on maximum residues and mean residues

ranged from <1 to 200 and <1 to 70, respectively. For major use sites, including rangeland/pasture,

RQs were approximately 100. These chronic risk estimates are likely conservative as described

below.

Exposure

The chronic RQs calculated for mammalian herbivores/insectivores are based on conservative

estimates of exposure that are not likely to occur in nature. In the example of pasture/rangeland, the

chronic RQ of approximately 100 for maximum residues (35 for mean residues) was calculated based

on an application rate of 4 lbs ae/A. This maximum application rate was determined based on the

knowledge that the maximum rate of 2 lbs ae/A may be applied twice per year, at a 30 day interval. 

However, the Biological and Economic Analysis Division within OPP has determined that the

average application rate on pasture/rangeland is only 0.62 lbs ae/acre (BEAD QUA). Moreover,

information from several state contacts indicate that a once per year application of less than 1 lb ae/A
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is typical (personal communications). As the typical rate is approximately 25% of the assessed rate,

use of the typical rate would be expected to decrease the RQ for the pasture/rangeland scenario to

approximately 25 for maximum residues and 9 for mean residues.

A second example of the conservative assumptions included in the assessment of exposure to

mammalian herbivores/insectivores is the assumption that 100% of the long term diet is limited to

single food types foraged only from treated fields. The assumption of 100% diet from a single food

type may be realistic for acute exposures, but diets are likely to be more variable over longer periods

of time. Moreover, currently Agency models do not account for the uptake of 2,4-D by plants and

therefore assume that all non-dissipated pesticide applied to the field is present for exposure to

organisms. In fact, many pesticides, including 2,4-D, are systemic and are absorbed by plants in the

field so that the current approach may overestimate the amount of 2,4-D available for exposure in

terrestrial systems. Therefore, the percent of diet assumption is likely to be conservative and will tend

to overestimate potential risks for chronic exposure, especially for larger organisms that have larger

home ranges.

Hazard

The mammalian chronic risk assessment utilized a toxicity endpoint from a rat two-generation

reproduction test. This endpoint was the NOAEL of 5 mg/kg-bw/day for growth rate reductions in

F1b offspring. The agency considers that reduced growth (reductions in pup body weight gains

relative to controls) in offspring as a potentially important effect with implications for the

survivability of offspring and therefore a potential impact on fecundity. Because the endpoint is the

no effect level for this measured parameter, evaluations of the significance of any exposures above

this endpoint were conducted. From the same two-generation rat reproduction study, the LOAEL

associated with F1b pup growth rate reduction was 20 mg/kg-bw/day. This LOAEL corresponds

with body-weight gain reductions of 15 to 17 % (males and females) relative to controls. The 20

mg/kg-bw/day dose level also represents a NOAEL for increased gestational length and incidents of

skeletal anomalies and reduced ossification in F1b pups. The LOAEL for these gestational and

skeletal effects is 80 mg/kg-bw/day.

In addition to the available rat two generation reproduction study, a number of developmental

toxicity studies are available in rats and rabbits for the acid, amine salts and esters. These data are

from studies involving short-term exposures during critical periods of fetal development and are

useful to determine if long-term or short-term exposure events are necessary for the types of effects

observed in the two-generation reproduction study. MRID 41747601, developmental toxicity in

rabbits with the acid, shows a NOAEL of 30 mg/kg-bw/day for increased rate of fetal abortions, with

a LOAEL 90 mg/kg-day. Similar NOAEL and LOAEL thresholds were observed in studies in

rabbits with the amine salts and esters of 2,4-D. MRID 000251031, developmental toxicity in rats

with the acid, showed a NOAEL of 25 mg/kg-bw/day and a LOAEL of 75 mg/kg-bw/day for

increased incidence of skeletal malformations. Similar results are reported in other studies with rats

involving the amine salt and esters of 2,4-D.

c. Characterization of risk to birds from terrestrial use

The assessment of risk to birds from exposure to 2,4-D is likely conservative as follows. 

Currently, Agency models do not account for the uptake of 2,4-D by plants and therefore assume that
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all non-dissipated pesticide applied to the field is present for exposure to organisms. In fact, many

pesticides, including 2,4-D, are systemic and are absorbed by plants in the field and therefore, the

current approach may overestimate the amount of 2,4-D available for exposure in terrestrial and

aquatic systems. 

For non-granular spray application, the highest acute avian RQ (3.50) was from the cranberry

scenario, for birds feeding on short grass. That assessment was based on a maximum application rate

of 4 lbs ae/acre; however, the average application rate is 1.83 lbs ae/acre (see the BEAD QUA). If the

modeled application rate was reduced to 1.83 lbs ae/acre for cranberries, and an assumption made that

the resulting EEC will be reduced linearly, the RQ would be 1.60. 

To determine the hazard associated with acute exposures to birds, the assessment has

considered two types of data, a suite of dietary studies and a suite of gavage studies. For avian acute

exposures, the dietary studies result in non-definitive endpoints which are not appropriate for

estimating risk. Therefore, the assessment has relied on the gavage studies to estimate avian acute

risks. The Agency recognizes that this approach may overestimate risk to birds due to the fact that

birds would not typically be expected to consume 2,4-D in this manner.

Given the conservative assumptions in both exposure scenarios and hazard determinations, the

Agency finds that the acute risk to birds from 2,4-D exposure does not exceed the Agency’s level of

concern.

Potential chronic risks to birds is limited to a few use sites. These include non-cropland, forest,

asparagus, and cranberry. The RQs for these sites range from 1 -1.09. Further characterization of

these use sites by evaluating average application rates versus maximum application rates lower these

RQs to below the LOCs.

d. Characterization of risk to non-target plants from terrestrial use

Acute LOCs for both non-endangered and endangered terrestrial plants were exceeded for nongranular and granular uses at many use sites. Consideration of average application rates did not result

in exposure below LOCs. However, the exposure estimates used to develop the RQs were likely

conservative, as follows. 

In the exposure calculation for non-target plants, the major contributor is run-off from the

application site. The runoff and leaching vulnerability schemes used in this assessment were adapted

from a vulnerability scheme developed by the USDA (Kellogg et al, 1998), and incorporate several

conservative assumptions. For example, a 1-in-10 year rain event is modeled, resulting in 3 cm of

runoff water. USDA identified several caveats to be considered when using this vulnerability scheme

which could contribute to the uncertainty associated with this assessment. Among these are that

estimates of runoff and leaching vulnerability are estimated through the use of algorithms (i.e. they

represent estimates of vulnerability and not actual field measurements), fate and transport processes

(i.e. dilution and recharge) are not included, farm management practices are not considered, and some

watershed estimates are based on major crops only. The effect of these factors on the vulnerability

assessment is unknown, however, there is a low probability that a 1-in-10 year rain event will

coincide with the first few days following a 2,4-D application at the maximum application rate. Also,

it is likely that farm management practices would be in place to limit run-off, as run-off events are

detrimental to the farm as a whole for reasons other than pesticide damage.

Currently Agency models do not account for the uptake of 2,4-D by plants and therefore

assume that all non-dissipated pesticide applied to the field is present for exposure to organisms. In

fact, many pesticides, including 2,4-D, are systemic and are absorbed by plants in the field and
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therefore, the current approach may overestimate the amount of 2,4-D available for exposure in

terrestrial and aquatic systems. 
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IV. Risk Management, Reregistration, and Tolerance Reassessment Decision

A. Determination of Reregistration Eligibility

Section 4(g)(2)(A) of FIFRA calls for the Agency to determine, after submission of relevant

data concerning an active ingredient, whether or not products containing the active ingredient are

eligible for reregistration. The Agency has previously identified and required the submission of the

generic (i.e., active ingredient-specific) data to support reregistration of products containing 2,4-D 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 2,4-D .

The Agency has completed its assessment of the dietary, occupational, residential, and

ecological risk associated with the use of pesticide products containing the active ingredient 2,4-D . 

Based on a review of these data and on public comments on the Agency’s assessments for the active

ingredient 2,4-D , the Agency has sufficient information on the human health and ecological effects

of 2,4-D to make decisions as part of the tolerance reassessment process under FFDCA and

reregistration process under FIFRA, as amended by FQPA. The Agency has determined that 2,4-D

containing products are eligible for reregistration provided that: (i) current data gaps and confirmatory

data needs are addressed; (ii) the risk mitigation measures outlined in this document are adopted; and

(iii) label amendments are made to implement these measures. Label changes are described in

Section V. Appendix A summarizes the uses of 2,4-D that are eligible for reregistration. Appendix B

identifies the generic data requirements that the Agency reviewed as part of its determination of

reregistration eligibility of 2,4-D, and lists the submitted studies that the Agency found acceptable. 

Data gaps are identified as generic data requirements that have not been satisfied with acceptable

data.

Based on its evaluation of 2,4-D, the Agency has determined that 2,4-D products, unless labeled

and used as specified in this document, would present risks inconsistent with FIFRA. Accordingly,

should a registrant fail to implement any of the risk mitigation measures identified in this document,

the Agency may take regulatory action to address the risk concerns from the use of 2,4-D . If all

changes outlined in this document are incorporated into the product labels, then all current risks for

2,4-D will be adequately mitigated for the purposes of this determination.

B. Public Comments and Responses

Through the Agency’s public participation process, EPA worked extensively with stakeholders

and the public to reach the regulatory decisions for 2,4-D . During the public comment period on the

revised risk assessments, which closed on March 14, 2005, the Agency received comments from

numerous parties. These comments in their entirety are available in the public docket (OPP-2004-

0167) at http://www.epa.gov/edockets. Individual responses to these comments are also available in

the public docket (OPP-2004-0167).

The RED and technical supporting documents for 2,4-D are available to the public through

EPA’s electronic public docket and comment system, EPA Dockets, under docket identification

number OPP-2004-0167. The public may access EPA Dockets at http://www.epa.gov/edockets. In
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addition, the 2,4-D RED may be downloaded or viewed through the Agency’s website at

http://www.epa.gov/pesticides/reregistration/status.htm.

C. Regulatory Position

1. Food Quality Protection Act Findings

a. “Risk Cup” Determination

As part of the FQPA tolerance reassessment process, EPA assessed the risks associated with

this pesticide. EPA has determined that risk from dietary (food sources only) exposure to 2,4-D is

within its own “risk cup.” An aggregate assessment was conducted for exposures through food,

drinking water, and residential uses. The Agency has determined that the aggregate human health

risks from these combined exposures are within the risk cup. In other words, EPA has concluded that

the tolerances for 2,4-D meet FQPA safety standards. In reaching this determination, EPA has

considered the available information on the special sensitivity of infants and children, as well as

aggregate exposure from food, water, and residential uses. 

b. Determination of Safety to U.S. Population

The Agency has determined that the established tolerances for 2,4-D , 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 no harm will result to the

general population or any subgroup from the use of 2,4-D. In reaching this conclusion, the Agency

has considered all available information on the toxicity, use practices and exposure scenarios, and the

environmental behavior of 2,4-D . Both the acute dietary (food alone) and chronic dietary risk from

2,4-D are not of concern. 

Acute and chronic risks from drinking water exposures are not of concern. Models have been

used to estimate surface water concentrations. The surface water EECs are below the DWLOCs for

all population subgroups. Drinking water monitoring data from the USGS NAWQA Program

confirm that concentrations of 2,4-D are less than modeled estimates for surface water. The

maximum concentration detected in ground water monitoring (from USGS NAWQA) has been used

as the ground water EEC. The ground water EEC is below the DWLOCs for all populations

subgroups. 

EPA has determined that the established tolerances for 2,4-D, 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, 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 2,4-D residues in this population subgroup. FQPA directs EPA, in setting

pesticide tolerances, to use an additional tenfold margin of safety to protect infants and children,

taking into account the potential for pre- and postnatal toxicity and the completeness of the toxicology

and exposure databases. The statute authorizes EPA to replace this tenfold FQPA safety factor with a
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different FQPA factor only if reliable data demonstrate that the resulting level of exposure would be

safe for infants and children.

FQPA Special Safety Factor

EPA concludes that the toxicology database for 2,4-D is substantially complete since all

required studies have been submitted. After evaluating hazard and exposure data for 2,4-D, EPA

removed the default 10X FQPA special safety factor. The toxicity database for 2,4-D includes

acceptable developmental and reproductive toxicity studies. Developmental toxicity studies were

conducted in both rats and rabbits for most 2,4-D forms. There is qualitative evidence of

susceptibility in the rat developmental toxicity study with 2,4-D acid and DEA salt where fetal effects

(skeletal abnormalities) were observed at a dose level that produced less severe maternal toxicity

(decreased body-weight gain and food consumption). There is no evidence of increased (quantitative

or qualitative) susceptibility in the prenatal developmental toxicity study in rabbits or in the 2-

generation reproduction study in rats on 2,4-D. Regarding the 2,4-D amine salt and ester forms, no

evidence of increased susceptibility (quantitative or qualitative) was observed in the prenatal

developmental toxicity study in rat and rabbits (except for 2,4-D DEA) dosed with any of the amine

salts or esters of 2,4-D. There is evidence of increased susceptibility (qualitative) in the prenatal

developmental study in rabbits for 2,4-D DEA salt.

After establishing developmental toxicity endpoints to be used in the risk assessment with

traditional uncertainty factors (10x for interspecies variability and 10x for intraspecies variability), the

Agency has no residual concerns for the effects seen in the developmental toxicity studies. Therefore,

the 10X FQPA special safety factor was reduced to 1X.

Database Uncertainty Factor

The EPA has concluded that there is a concern for developmental neurotoxicity resulting from

exposure to 2,4-D, and that a developmental neurotoxicity (DNT) study in rats is required for 2,4-D. 

The Agency has also concluded that a 2-generation reproduction study is required to address both the

concern for thyroid effects and immunotoxicity, as well as a more thorough assessment of the gonads

and reproductive/developmental endpoints. EPA has determined that a 10X database uncertainty

factor (UFDB) is needed to account for the lack of these studies. This Uncertainty Factor is applied

only to exposure scenarios that are expected for children or pregnant women, and thus is not applied

to occupational exposure scenarios.

2. Endocrine Disruptor Effects

EPA is required under the FFDCA, as amended by FQPA, to develop a screening program to

determine whether certain substances (including all pesticide active and other ingredients) “may have

an effect in humans that is similar to an effect produced by a naturally occurring estrogen, or other

endocrine effects as the Administrator may designate.” When the appropriate screening and/or

testing protocols being considered under the EDSP have been developed, 2,4-D may be subject to

additional screening and/or testing to better characterize effects related to endocrine disruption.

3. Cumulative Risks
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The Food Quality Protection Act (FQPA) requires EPA to consider "available information"

concerning the cumulative effects of a particular pesticide's residues and "other substances that have a

common mechanism of toxicity" when considering whether to establish, modify, or revoke a

tolerance. Potential cumulative effects of chemicals with a common mechanism of toxicity are

considered because low-level exposures to multiple chemicals causing a common toxic effect by a

common mechanism could lead to the same adverse health effect as would a higher level of exposure

to any one of these individual chemicals. 2,4-D is a member of the alkylphenoxy herbicide class of

pesticides. A cumulative risk assessment has not been performed as part of this human health risk

assessment because the Agency has not yet made a determination of whether 2,4-D and other

alkylphenoxy compounds have a common mechanism of toxicity. For information regarding EPA’s

efforts to determine which chemicals have a common mechanism of toxicity and to evaluate the

cumulative effects of such chemicals, see the policy statements by the EPA’s Office of Pesticide

Programs concerning common mechanism determinations and procedures for cumulating effects

from substances found to have a common mechanism on EPA’s website at

http://epa.gov/pesticides/cumulative/.] 

4. Special Review Disposition

2,4-D has been in pre-Special Review status since September 22, 1986, because of

carcinogenicity concerns. In 1994 a Science Advisory Panel/Scientific Advisory Board classified

2,4-D as a Group D carcinogen (not classifiable to human carcinogenicity). The Agency requested

further histopathological examinations of rat brain tissues and mouse spleen tissues in question. 

These exams were submitted and reviewed, and on March 16, 1999, The Agency notified the 2,4-D

Task Force that the Agency would continue to classify 2,4-D as a Group D carcinogen. Also, in a

1994 review of all relevant epidemiological studies, EPA found that none of the more recent

epidemiological studies definitively linked human cancer cases to 2,4-D. A final notice of the

Agency’s intent not to initiate Special Review will be published in concert with the release of this

RED document.

5. Dioxin Contaminants

Exposure

In 1987, a DCI titled “Data Call-In Notice for Product Chemistry Relating to Potential

Formation of Halogenated Dibenzo-p-dioxin or Dibenzofuran Contaminants in Certain Active

Ingredients,” was issued to identify pesticides that may contain halogenated dibenzo-p-dioxin and

dibenzofuran contaminants. A second DCI in 1987, “Data Call-In for Analytical Chemistry Data on

Polyhalogenated Dibenzo-p-Dioxins/Dibenzofurans (HDDs and HDFs),” was issued, under which

registrants whose products did not qualify for an exemption or waiver were required to generate and

submit analytical methods and certification limits of dioxins and furans.

The specific results of analysis of multiple 2,4-D technical products, submitted to EPA in

response to both DCIs, are considered confidential business information (CBI) and cannot be released

by EPA to the public. In summary, two of eight technical products had concentrations of 2,3,7,8-

tetrachlorodibenzo-p-dioxin (TCDD; dioxin) greater than the limit of quantitation (LOQ; LOQ = 0.1

ppb) and three of eight had concentrations of 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PCDD) greater

than the LOQ (LOQ = 0.5 ppb). 

In 1991, the EPA’s Office of Research and Development (EPA/ORD) began an assessment of
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the health risks of exposure to dioxins. The most recent revision of that assessment has recently been

submitted to the National Academies of Science (NAS) for review. In that document and elsewhere,

a source inventory of dioxin was published. As a result of the 1987 DCI data, and the amount of 2,4-

D applied to agricultural and residential settings (approximately 50 million pounds per year), the

current draft dioxin source inventory (see The Inventory of Sources and Environmental Releases of

Dioxin-Like Compounds in the United States: The Year 2000 Update, EPA/600/P-03/002A, External

Review Draft, March 2005) identifies 2,4-D as a source of dioxin emissions (28.9 g TEQDFWHO98; TEQ = Toxic EQuivalent amount, or an amount of total dioxin equivalent to 28.9 g of the

most toxic dioxin congener, 2,3,7,8-TCDD). It should be noted that this estimate of dioxin release

assumes all products are contaminated and does not take into account manufacturing changes since

the DCI. Moreover, that estimate is specific for the year 1995, and therefore should not be considered

the current estimate of dioxin release. 

The 1995 estimate for dioxin emissions from 2,4-D, taken together with NAS estimates for

2002/2004 releases from other sources of dioxin in the U.S., suggest that 2,4-D applications to land

ranks seventh (2.6% of all dioxin sources) behind backyard burning (57%), sewage sludge application

(6.9%), residential wood burning (5.7%), coal-fired utilities (5.4%), diesel trucks (3.2%), and

secondary aluminum smelting (2.6%) in terms of dioxin emissions (see The Inventory of Sources and

Environmental Releases of Dioxin-Like Compounds in the United States: The Year 2000 Update,

EPA/600/P-03/002A, External Review Draft, March 2005). According to 2,4-D registrants, since the

1990’s, the manufacturing processes for 2,4-D and its chemical intermediate, dichlorophenol, have

been modified, and those modifications decrease the chance that TCDD and PCDD are formed during

the manufacturing process. The following description of the current 2,4-D manufacturing process

summarizes information submitted by the 2,4-D Task Force II. 

A key chemical intermediate in the manufacture of 2,4-D is 2,4-dichlorophenol (2,4-DCP) and

the purity of this intermediate has a strong correlation to the purity of 2,4-D acid produced from it. In

the manufacture of 2,4-DCP, multiple positions around the phenyl ring structure may be chlorinated.

The desired positions for chlorination are carbons two and four of the phenyl ring, but the reaction

may yield small quantities of compounds chlorinated at different positions. Certain combinations of

these chlorinated structures may form precursors to the dioxin 2,3,7,8-TCDD. 

Manufacture of the 2,4-DCP intermediate has been optimized by controlling processing

conditions necessary to drive the chlorination reaction to the preferred two and four carbon positions,

thereby limiting the formation of impurities that can lead to dioxin formation. Controlled temperature

and residence time during the chlorination reaction, programmed addition of the chlorinating agent,

and efficient agitation in the reaction vessel are processing factors that contribute to the purity of 2,4-

DCP. Additionally, distillation of 2,4-DCP is a technique that may be employed post-chlorination to

increase purity. Moreover, quality control sampling and analytical procedures are also utilized to

verify product quality at various steps of the 2,4-DCP process. According to Results of testing of 

2,4-DCP, performed in response to the Toxic Substances Control Act (TSCA) Dioxin/Furan Test

Rule, showed no detectable concentrations of 2,3,7,8-substituted tetra- through hepta-CDD/CDFs.

In the manufacture of 2,4-D acid per se, there are additional process conditions and procedures

that must be controlled to maximize yield and purity. Details regarding these measures are dependent

on specific manufacturing methodologies and, as such, are protected under FIFRA Section 10 as

Confidential Business Information. 

Anticipated Residues
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The Agency’s most recent evaluations of anticipated dioxin and furan residues resulting from

2,4-D applications are based on the concentrations of dioxins and furans present in technical grade

2,4-D as determined by review of analytical data submitted in response to the 1987 DCI. In those

evaluations, completed in the early 1990's, the ratios of individual chlorodibenzo-p-dioxin (CDD;

dioxin) or chlorodibenzo-p-furan (CDF; furan) contaminant concentrations to 2,4-D acid

concentrations were calculated, and those ratios were used with 2,4-D tolerance expressions to

calculate an anticipated residue in eggs, fruits, grains, kidney (hogs), meat (hogs), milk, nuts, poultry,

and sugarcane, for each detected dioxin or furan. For each technical 2,4-D formulation for which the

Agency received data, calculation of an anticipated dietary exposure was based on a worst-case

scenario in which the highest anticipated residue was used, and an assumption was made that 100%

of the diet consisted of the food item with the highest anticipated residue. 

Toxicological Significance

Based on the calculation of dietary exposures, using the worst-case scenario described above,

both the cancer and non-cancer risks from dietary exposure to dioxins and furans as contaminants of

2,4-D acid were considered to be of no toxicological concern at the time of the assessment.

Risk Management

Members of the 2,4-D Task Force II have submitted information about the current

manufacturing process for the 2,4-D intermediate, 2,4-DCP, as well as for 2,4-D acid itself, and have

included in their submissions explanatory text on how current manufacturing processes minimize the

chance of dioxin and furan formation. To confirm that the changes to the manufacturing processes

since the time of the 1987 DCI have resulted in lower concentrations of dioxin congeners in technical

2,4-D products, the Agency is requiring that five recent batches of all technical products be analyzed

for 2,3,7,8-TCDD, 2,3,7,8-TCDF and their respective higher substituted chlorinated congeners using

validated analytical methods. The Agency is specifying that the manufacturers use the most current

state-of-the art laboratory methods for measuring 2,3,7,8-TCDD and TCDF at levels less than 1 part

per trillion (EPA Method 1613, Tetra- through Octa-Chlorinated Dioxins and Furans by Isotope

Dilution HRGC/HRMS). Because 1,2,3,7,8-PeCDD is equi-potent to 2,3,7,8-TCDD in the TEF

scheme, the Agency is adding this compound to our testing requirements. The pentachloro-congener

was reported as present in 2,4-D in the 1987 Data Call-in. Registrants are encouraged to submit their

analytical methods and sampling plans to the Agency for review prior to commencing these studies.

D. Tolerance Reassessment Summary

1. Tolerances Currently Listed Under 40 CFR §180.142

Tolerances for residues of 2,4-D in/on plant RACs and processed commodities, fish, and

potable water are currently expressed in terms of 2,4-D per se [40 CFR §180.142(a)(1-6 and 9-12)

and (b)]. Tolerances for residues in livestock commodities are currently expressed in terms of 2,4-D

and/or its metabolite 2,4-dichlorophenol (2,4-DCP) [40 CFR §180.142(a)(8)]. EPA has concluded

that 2,4-D is the residue of concern and that tolerances listed in 40 CFR §180.142 are to be defined as

residues of 2,4-D, both free and conjugated, determined as the acid.

The listing for 2,4-D tolerances in 40 CFR §180.142 should be recodified into parts (a), (b), (c),

and (d). Part (a) should be reserved for commodities with permanent tolerances reflecting at least a
Page 85 of 304

preharvest (field) or postharvest use, part (b) for Section 18 emergency exemptions, part (c) for

tolerances with regional use registrations, and part (d) for commodities bearing 2,4-D residues solely

inadvertently, including irrigated crops. A summary of 2,4-D tolerance reassessments and

recommended recodifications is presented in Table 37 along with any recommended changes in

commodity definitions.

Note that some commodities currently are the subject of two or more separate tolerances

depending on the use pattern, the 2,4-D form applied, timing of treatment (preharvest or postharvest),

or degree of intent to deposit residues (direct treatment or inadvertent). Direct treatment involves

intentional field treatment of crop sites or postharvest treatment of harvested commodities on

registered labels. Inadvertent deposition involves the incidental exposure of crops when water

passing through 2,4-D-treated irrigation ditchbanks or diverted from 2,4-D-treated bodies of water is

used to irrigate crops. EPA is proposing to remove most such use-pattern or FIFRA-related language

at 180.142. Due to the complicated nature of the routes of residue deposition, we are proposing to

subsume the lower tolerances in the highest existing or reassessed tolerance established in the same

commodity - even if that results in 180.142(a) containing some tolerances that reflect 2,4-D residues

that could potentially result from two or more exposure routes. An example is citrus which has

tolerances for 2,4-D in the RAC resulting from preharvest use + postharvest use, irrigation ditchbank

treatment (inadvertent), and direct water body treatment (also inadvertent). If there are no registered

uses on a given commodity and residues are likely to occur on that commodity solely inadvertently,

i.e., via irrigation, then the tolerance in that commodity will be located under 180.142(d). In most

cases, residues, and hence the tolerance, resulting from a direct, registered use are higher than the

residues (and the tolerance) resulting inadvertently. EPA proposes these revisions because we know

that an enforcement agency, having detected 2,4-D residues in a commodity, would: (i) not be able to

distinguish which form of 2,4-D had been applied; (ii) rarely be able to determine who applied the

pesticide, when, or for what purpose; and (iii) not know whether a sample is violative if the 2,4-D

concentration falls between two tolerance levels.

Tolerances Listed Under 40 CFR §180.142(a)(1):

Adequate data are available to reassess the established tolerances for the following

commodities: apple, apricot, citrus fruit, pear, potato and quince.

The available apple and pear residue data will support a crop group tolerance at 0.05 ppm for

pome fruits under the redesignated section 180.142(a). The separate tolerances on apple, pear, and

quince should be revoked concomitant with establishing a new pome fruit crop group tolerance.

The 5 ppm tolerance on citrus fruits should be reassessed to 3.0 ppm to reflect any combination

of the preharvest use on citrus, the postharvest use of 2,4-D on lemons in the U.S., a similar

postharvest use on oranges imported into the U.S., and any inadvertent (irrigation) residues that may

be incurred as a result of 2,4-D use in aquatic sites. The tolerances in citrus fruit of 0.1 ppm at

180.142(a)(3) and 1.0 ppm at 180.142(a)(6), both reflecting inadvertent residues, should be revoked

as they will be subsumed by the reassessed tolerance of 3.0 ppm at 180.142(a). 

The tolerance for residues in/on apricots should be revoked as residues in/on apricots will be

covered by the tolerance in stone fruits.

Tolerances Listed Under 40 CFR §180.142(a)(2):
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Adequate data are available to reassess all the tolerances listed under 180.142(a)(2). All

reassessed tolerances should be recodified under the revised section 180.142(a). 

Based on the available residue data, the current tolerances on grass hay and tree nuts are

adequate. However, tolerances can be lowered on the following commodities: blueberry, sweet corn

(kernel plus cob with husks removed), corn forage and grain, cranberry, stone fruits, grape, grass

forage, pistachio, rice straw, sorghum forage, grain and stover, and sugarcane. Tolerances should be

increased on the following commodities: corn stover, rice grain, and wheat grain and forage. 

The available residue data for wheat commodities will be used to reassess tolerances on similar

commodities from barley, millet, oats, and rye. Tolerances should be increased accordingly on:

barley grain; millet grain, forage and straw; oat forage and grain; and rye forage and grain.

The tolerance for residues in sugarcane forage should be revoked because it is no longer

considered a significant livestock feed item (OPPTS GLN 860.1000).

Tolerances Listed Under 40 CFR §180.142(a)(3):

Tolerances listed in 40 CFR §180.142(a)(3) are established for negligible residues of 2,4-D in

irrigated crops from application of its dimethylamine salt to irrigation ditch banks in the Western

United States in programs of the Bureau of Reclamation, U.S. Department of Interior; cooperating

water user organizations; the Bureau of Sport Fisheries, U.S. Department of Interior; Agricultural

Research Service, U.S. Department of Agriculture; and the Corps of Engineers, U.S. Department of

Defense. Where tolerances are established at higher levels resulting from other uses of 2,4-D, the

higher tolerance applies also to residues in crops from the irrigation ditch bank use cited in this

paragraph.

The tolerances in crops or crop groups listed under 40 CFR §180.142(a)(3) that do not have a

direct treatment tolerance under 180.142(a) should be recodified as 180.142(d), i.e., inadvertent

residue tolerances. 

The available irrigated crop data support tolerances for inadvertent residues at 0.2 ppm in

foliage of legume vegetables (group 7) and non-grass animal feed (group 18) and at 0.05 ppm in/on

the following crops groups: bulb vegetables (group 3), legume vegetables (group 6), cucurbit

vegetables (group 9), and fruiting vegetables (group 8).

In addition, tolerances resulting from the primary use of 2,4-D on grasses, citrus fruits, and tree

nuts are high enough to cover any inadvertent residues in these crops that may result from the use of

2,4-D treated irrigation water. Therefore, separate tolerances for inadvertent residues in/on these

crops are not required.

Separate tolerances for inadvertent residues are unnecessary in pome fruits, stone fruits,

pistachios, grapes, blueberry, and strawberry as these crops all have tolerances resulting from the

direct use of 2,4-D. However, the tolerances in all of these commodities have been reassessed at 0.05

ppm, the limit of quantitation of the enforcement method, to reflect only direct treatment at this time.

It is reasonably possible that inadvertent residues resulting from irrigation with treated water could

contribute concentrations of 2,4-D in the commodities necessitating tolerances higher than 0.05 ppm. 

Therefore, confirmatory irrigated crop residue data are required for a representative perennial crop

(strawberry). Also, additional residue data on sugar beets and tops irrigated with water containing

2,4-D at 0.1 ppm are required to permit reassessment of the tolerances in the Root and Tuber

Vegetables Group and the Leaves of Root and Tuber Vegetables Group resulting inadvertently due to
Page 87 of 304

irrigation with 2,4-D-treated water. These data may also be used to reassess inadvertent tolerances

established at 180.142(d) as a result of the 2,4-D RED.

Tolerance Listed Under 40 CFR §180.142(a)(4):

The established tolerance for residues in/on asparagus is reassessed at the current level under

the revised tolerance expression and is to be recodified as 40 CFR §180.142(a).

Tolerance Listed Under 40 CFR §180.142(a)(5)

The established tolerance for residues in/on strawberry is reassessed at the current level under

the revised tolerance expression and is to be recodified as 40 CFR §180.142(a).

Tolerances Listed Under 40 CFR §180.142(a)(6):

Tolerances listed in 40 CFR §180.142(a)(6) are established for residues of 2,4-D from

application of its dimethylamine salt for water hyacinth control in ponds, lakes, reservoirs, marshes,

bayous, drainage ditches, canals, rivers, and streams that are quiescent or slow moving in programs

conducted by the Army Corps of Engineers or other Federal, State, or local public agencies. Where

tolerances are established at higher levels from other uses of the dimethylamine salt of 2,4-D on crops

included within these commodity groups, the higher tolerances also apply to residues from the aquatic

uses cited in this paragraph.

Based on the available residue data, the current tolerance in shellfish is adequate and the

tolerance in fish can be reduced to 0.1 ppm. Both tolerances should be recodified under the revised

section 180.142(a). 

Tolerances for residues in/on the irrigated crops and crop groups at the current §180.142(a)(6)

are set at 1.0 ppm whereas the tolerances in/on the identical crops/crop groups at §180.142(a)(3) are

at 0.1 ppm for the irrigation ditchbank use. The recommended/reassessed tolerances from

§180.142(a)(3) to be recodified under sections §180.142(a) or §180.142(d) concomitantly address the

reassessments/recodifications recommended for tolerances at §180.142(a)(6), depending on whether

residues are incurred directly and/or inadvertently, as explained above.

Tolerances Listed Under 40 CFR §180.142(a)(8):

Tolerances listed in 40 CFR §180.142(a)(8) are established for residues of 2,4-D and/or its

metabolite 2,4-DCP in livestock commodities. As indicated by the Agency, the regulated residue in

animal commodities is 2,4-D (free and conjugated). As a result of this residue definition change, all

reassessed livestock tolerances should be recodified to §180.142(a).

Based upon the available livestock feeding study, the 0.1 ppm tolerance in milk is reassessed at

0.05 ppm and the tolerances in cattle, goat, horse, and sheep commodities are reassessed at: 0.3 ppm

in fat, meat, and meat byproducts except kidney and 4.0 ppm in kidney.

The established tolerances for 2,4-D residues in hog commodities may be revoked. Based on

the MTDB for swine (1.6 ppm) and the results of the ruminant feeding study, there is no reasonable

expectation of finite 2,4-D residues occurring in hog commodities [Category 3 of 40 CFR

§180.6(a)(3)].

In addition, the established tolerances for 2,4-D residues in eggs and poultry tissues may be

revoked. Based on the results of the 2,4-D poultry metabolism study, there is no reasonable

expectation of finite residues in poultry tissues and eggs [Category 3 of 40 CFR §180.6(a)(3)].
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Tolerance Listed Under 40 CFR §180.142(a)(9):

Tolerances listed in 40 CFR §180.142(a)(9) are established for residues of 2,4-D from

applications of its dimethylamine salt or its butoxyethanol ester for Eurasian water milfoil control in

programs conducted by the Tennessee Valley Authority in dams and reservoirs of the TVA system.

The tolerance for 2,4-D residues in fish at 40 CFR §180.142(a)(9) should be revoked and this

section deleted. There is no need for two 2,4-D tolerances in fish. It has already been recommended

that the 1.0 ppm tolerance in fish currently at §180.142(a)(6) be reassessed at 0.1 ppm and that this

reassessed tolerance be recodified at the new 40 CFR §180.142(a).

Tolerance Listed Under 40 CFR §180.142(a)(10):

The tolerance listed in 40 CFR §180.142(a)(10) is a regional registration as defined in Sec.

180.1(n) and is established for the residues of 2,4-D in raspberries. The tolerance includes residues

from the application of 2,4-D and its N-oleyl-1,3-propylenediamine salt.

As the members of Task Force II are not supporting 2,4-D use on this commodity, the tolerance

for residues in/on raspberries should be revoked unless another party wishes to support a use on this

crop. 40 CFR §180.142(a)(10) should be deleted and any tolerances with regional use registration

should be established under the revised section 40 CFR §180.142(c).

Tolerance Listed Under 40 CFR §180.142(a)(11):

A time-limited tolerance of 0.02 ppm has been established for residues of 2,4-D resulting from

the preplant use of 2,4-D ester or amine in/on soybean seed [40 CFR §180.142(a)(11)], expired on

December 31, 2004. Adequate residue data are available to support permanent tolerances on soybean

commodities. Section 180.142(a)(11) should be deleted, and permanent tolerances for 2,4-D residues

in/on soybean seed, forage, and hay are recommended to be established under the revised section

180.142(a).

Tolerances Listed Under 40 CFR §180.142(a)(12):

Tolerances listed at 40 CFR §180.142(a)(12) are established for residues of 2,4-D in processed

feeds. Such residues may be present therein only as a result of application to the growing crop of the

herbicides identified in this section. Tolerances formerly listed at 40 CFR §180.1450 were moved to

40 CFR §180.142(a)(12) (63 FR 34829, 6/26/98).

The tolerance for residues in sugarcane bagasse should be revoked because it is no longer

considered a significant livestock feed item and has been deleted from Table 1 (OPPTS GLN

860.1000).

40 CFR §180.142(a)(12) should be deleted. The tolerance for 2,4-D residues in milled fractions

derived from barley, oats, rye, and wheat should be revoked as the commodity definition will change

and the tolerances will be increased and recodified at the revised 40 CFR §180.142(a) for residues in

barley bran, rye bran, and wheat bran. No tolerances in other processed products of small grains are

necessary because concentration of residues does not occur in them.

Tolerances Listed Under 40 CFR §180.142(a)(13):

Tolerances listed at CFR §180.142(a)(13) are established for residues of 2,4-D in processed

foods and potable water.
Page 89 of 304

40 CFR §180.142(a)(13) should be deleted. The tolerances for 2,4-D residues in sugarcane

molasses and in milled fractions derived from barley, oats, rye, and wheat should be revoked as

tolerances will be recodified under the revised 40 CFR §180.142(a) for residues in sugarcane

molasses, barley bran, rye bran, and wheat bran.

The established tolerance for residues of 2,4-D in potable water should be revoked as

EPA/OPPTS/OPP no longer establishes pesticide tolerances in potable water. Instead, the EPA

Office of Water establishes Maximum Contaminant Levels (MCLs). An MCL of 0.07 ppm has been

established for 2,4-D in drinking water.

Tolerances Listed Under 40 CFR §180.142(b):

The tolerance listed in 40 CFR §180.142(b) is a time-limited tolerance established for 2,4-D

in/on wild rice in connection with use of 2,4-D in MN under a Section 18 emergency exemption

granted by EPA. The tolerance is set to expire on December 31, 2005. As adequate residue data are

available on wild rice grown in MN, a permanent tolerance for rice, wild, grain should be established

at 0.05 ppm under 40 CFR §180.142(c).

2. Tolerances to Be Proposed Under 40 CFR §180.142

Tolerances Needed Under 40 CFR §180.142(a):

The revised section will include all permanent tolerances for residues of 2,4-D, defined as

residues of 2,4-D, both free and conjugated, determined as the acid. The section will include all plant

commodities (excluding crop commodities exposed solely inadvertently), livestock commodities,

fish, and shellfish at reassessed levels.

In addition, the available residue data indicate that new tolerances should be established for 2,4-

D residues in/on the following commodities: almond hulls; aspirated grain fractions; barley bran and

straw; oat straw; rice hulls; rye bran and straw; soybean forage, hay, and seeds; and wheat bran and

straw.

Once adequate residue data become available, new tolerances should also be established for

wheat hay. Wheat hay data will be translated to barley hay, millet hay, and oat hay.

Tolerances Needed Under 40 CFR §180.142(c):

Based on the available residue data, tolerances with regional use registrations should be

established for wild rice grain at 0.05 ppm, reflecting the use of 2,4-D on wild rice grown in MN.

Tolerances Needed Under 40 CFR §180.142(d):

Tolerances for inadvertent 2,4-D residues in irrigated crops that have no registered, direct uses

will be moved from paragraph §180.142(a)(3) to paragraph §180.142(d) and the commodity and crop

group listings will be revised to the current EPA definitions.

Table 38. Tolerance Reassessment Summary for 2,4-D.

Commodity Tolerance Listed

Under 40 CFR

§180.142 (ppm)

Reassessed

Tolerance (ppm)

Comment

[Corrected Commodity Definition]

Tolerances Listed Under 40 CFR §180.142 (a) (1) 2
Commodity Tolerance Listed

Under 40 CFR

§180.142 (ppm)

Reassessed

Tolerance (ppm)

Comment

[Corrected Commodity Definition]

Page 90 of 304

Apple 5 Revoke A single tolerance should be established at 0.05

ppm under 180.142(a) for direct and inadvertent

residues in/on the Fruit, pome, group 11.

Apricot 5 Revoke Residues in/on apricots will be covered by the

tolerance for direct and inadvertent residues in stone

fruits at 180.142(a).

Fruit, citrus 5

3.0

A tolerance should be established in Fruit, citrus,

group 10, recodified as 180.142(a), that will cover

the preharvest use on citrus, the postharvest use on

lemons in the U.S., the postharvest use on citrus

imported into the U.S., and the inadvertent residues

due to irrigation with treated water.

Pear 5 Revoke A single tolerance should be established at 0.05

ppm under 180.142(a) for direct and inadvertent

residues in/on the Fruit, pome, group 11.

Potato 0.2 0.40 Includes direct and inadvertent (irrigation) residues.

Recodify as 180.142(a).

Quince 5 Revoke Residues in/on quince will be included under the

0.05 ppm tolerance at 180.142(a) for direct and

inadvertent residues in/on the Fruit, pome, group

11.

Tolerances Listed Under 40 CFR §180.142 (a) (2) 2

Barley, grain 0.5 2.0 The submitted data for wheat grain may be

translated to barley grain. Recodify as 180.142(a).

Blueberry 0.1 Revoke To be included under the 0.2 ppm Berries group 13

tolerance to be recodified as 180.142(a).

Corn, fodder 20 50.0 Residue data from the 7-day PHI. Recodify as

180.142(a). Corn, stover

Corn, forage 20 6.0 Residue data from the 7-day PHI. Recodify as

180.142(a).

Corn, fresh, sweet,

kernel plus cob with

husks removed

0.5 0.05 Recodify as 180.142(a).

Corn, grain 0.5 0.05 Residue data from 7-day PHI. Recodify as

180.142(a).

Cranberry 0.5 Revoke To be included under the 0.2 ppm Berries group 13

tolerance to be recodified as 180.142(a).

Fruit, stone 0.2 0.05 Recodify as 180.142(a). This tolerance will now

cover both direct and inadvertent residues. Fruit,

stone, group 12

Grape 0.5 0.05 Residue data on grape are available for the entire

U.S. Recodify as 180.142(a).

Grass, hay 300 300 Residue data from the 7-day posttreatment interval

(PTI) for Grass, hay. Recodify as 180.142(a).
Commodity Tolerance Listed

Under 40 CFR

§180.142 (ppm)

Reassessed

Tolerance (ppm)

Comment

[Corrected Commodity Definition]

Page 91 of 304

Grass, pasture 1,000 360 Recodify as 180.142(a). Residue data from the 0-

day PTI. This new tolerance will now cover both

direct and inadvertent residues. Grass, forage Grass, rangeland 1,000

Millet, forage 20 25 The data for wheat forage, grain, and straw may be

translated to millet forage, grain, and straw. The

required wheat hay data will be translated to millet

hay. Recodify as 180.142(a). This new tolerance

will now cover both direct and inadvertent residues.

Millet, grain 0.5 2.0

Millet, straw 20 50

Nut 0.2 0.2 Recodify as 180.142(a). This new tolerance will

now cover both direct and inadvertent residues. 

Nut, tree, group 14

Oat, forage 20 25 The data for wheat forage may be translated to oat

forage. Recodify as 180.142(a). This new tolerance

will now cover both direct and inadvertent residues.

Oat, grain 0.5 2.0 The data for wheat grain may be translated to oat

grain. Recodify as 180.142(a). This new tolerance

will now cover both direct and inadvertent residues.

Pistachio 0.2 0.05 Recodify as 180.142(a). This new tolerance will

now cover both direct and inadvertent residues.

Rice 0.1 0.5 Recodify as 180.142(a). This new tolerance will

now cover both direct and inadvertent residues. 

Rice, grain

Rice, straw 20 10 Recodify as 180.142(a). This new tolerance will

now cover both direct and inadvertent residues.

Rye, forage 20 25 Recodify as 180.142(a). This new tolerance will

now cover both direct and inadvertent residues. The

data for wheat forage may be translated to rye

forage.

Rye, grain 0.5 2.0 Recodify as 180.142(a). This new tolerance will

now cover both direct and inadvertent residues. The

data for wheat grain may be translated to rye grain.

Sorghum, fodder 20 0.2 Recodify as 180.142(a). This new tolerance will

now cover both direct and inadvertent residues. 

Sorghum, stover

Sorghum, forage 20 0.2 Recodify as 180.142(a). This new tolerance will

now cover both direct and inadvertent residues.

Sorghum, grain 0.5 0.2 Recodify as 180.142(a). This new tolerance will

now cover both direct and inadvertent residues.

Sugarcane 2 0.05 Recodify as 180.142(a). Sugarcane, cane

Sugarcane, forage 20 Revoke Sugarcane forage is no longer considered a

significant livestock feed item.
Commodity Tolerance Listed

Under 40 CFR

§180.142 (ppm)

Reassessed

Tolerance (ppm)

Comment

[Corrected Commodity Definition]

Page 92 of 304

Wheat, forage 20 25 Recodify as 180.142(a). This new tolerance will

now cover both direct and inadvertent residues. The

14-day PHI residue data on wheat forage and grain

will be used to support tolerances for residues in/on

similar commodities of barley, millet, oats, and rye.

Wheat, grain 0.5 2.0

Tolerance Listed Under 40 CFR §180.142 (a)(3) 4

Avocado 0.1(N) 0.05 Recodify as 180.142(d).

Cottonseed 0.1(N) 0.05 Recodify as 180.142(d). Cotton, undelinted seed

Cucurbits 0.1(N) 0.05 Recodify as 180.142(d). Vegetable, cucurbit, group

9

Fruit, citrus 0.1(N) Revoke Inadvertent residues will be covered by the crop

group tolerance on citrus fruit at 180.142(a).

Fruit, pome 0.1(N) Revoke Inadvertent residues will be covered by the crop

group tolerance on pome fruit at 180.142(a).

Fruit, stone 0.1(N) Revoke Revocation of one strone fruit tolerance is

necessary to avoid duplication. Inadvertent residues

will be covered by the stone fruit group tolerance at

180.142(a)(2) to be recodified as 180.142(a).

Grain, crop 0.1(N) Revoke Separate tolerances in RACs of each grain will be

individually established and recodified as

180.142(a) in/on grain, forage, fodder, stover, or

hay, as applicable, to cover both direct and

inadvertent residues. Upon formal Agency

approval, a small grains subgroup tolerance may be

established.

Grass, forage 0.1(N) Revoke Inadvertent residues will be covered by the grass

forage tolerance for direct residues to be recodified

as 180.142(a).

Hop 0.1(N) 0.2 Inadvertent residues will be covered by the hop

tolerance for direct residues upon establishment at

180.142(a) in response to PP#2E6352.

Leafy vegetables 0.1(N) 0.4 Establish separate tolerances for inadvertent

residues in the Vegetable, leafy, except brassica,

group 4 and Vegetable, brassica, leafy, group 5 at

0.4 ppm under the revised 180.142(d)

Legume, forage 0.1(N) Group 7 - 0.2

Group 18 - 0.2

Establish separate tolerances for the Vegetable,

foliage of legume, group 7 and Animal feed,

nongrass, group 18 for inadvertent residues under

180.142(d).

Nut 0.1(N) Revoke Inadvertent residues will be covered by the

tolerance in the tree nuts crop group at 180.142(a)
Commodity Tolerance Listed

Under 40 CFR

§180.142 (ppm)

Reassessed

Tolerance (ppm)

Comment

[Corrected Commodity Definition]

Page 93 of 304

Root crop vegetables 0.1(N) Group 1 - TBD

Group 2 - TBD

Group 3 - 0.05

Additional data are required to determine

inadvertent residues in sugar beet roots and tops to

represent root and tuber vegetables. Establish

separate tolerances in the Vegetable, bulb, group 3.

When sugar beet data are received, establish

separate tolerances in the Vegetable, root and tuber,

group 1 and Vegetable, leaves of root and tuber,

group 2. Recodify as 180.142(a).

Seed and pod

vegetables

0.1(N) 0.05 Establish tolerance for inadvertent residues at

180.142(d) in the Vegetable, legume, group 6.

Small fruit 0.1(N) 0.2 The 0.2 ppm tolerance in the Berries group 13, to be

recodified at §180.142(a), will also cover

inadvertent residues. Inadvertent residues in/on

blueberry and cranberry will also be covered by this

group tolerance. Inadvertent residues in/on grape

and strawberry will be covered by separate

tolerances for direct uses on these crops

§180.142(a). 

Vegetable, fruiting 0.1(N) 0.05 Establish tolerance for inadvertent residues at 0.05

ppm in the Vegetable, fruiting, group 8 recodified

under §180.142(d).

Tolerance Listed Under 40 CFR §180.142 (a)(4) 2

Asparagus 5 5.0 Recodify as §180.142(a).

Tolerance Listed Under 40 CFR §180.142 (a)(5) 2

Strawberry 0.05 0.05 Recodify as §180.142(a). This tolerance will cover

direct and inadvertent residues.

Tolerance Listed Under 40 CFR §180.142 (a)(6) 2

Crops in paragraph

(c) of this section 

1.0 Revoke The tolerances to be established under paragraphs

§180.142(a) and §180.142(d) will be sufficient to

cover inadvertent residues in irrigated crops under

the recodified §180.142(a)(6).

Crop groupings in

paragraph (c) of this

section 

1.0 Revoke The tolerances to be established under paragraphs

§180.142(a) and §180.142(d) will be sufficient to

cover inadvertent residues in irrigated crops under

the recodified §180.142(a)(6).

Fish 1.0 0.10 Residue data for fish and shellfish are from recent

tests where fish and shellfish were exposed to 2,4-D

under static conditions at 6.0 ppm (1.5x). Recodify

to §180.142(a).

Shellfish 1.0 1.0

Tolerance Listed Under 40 CFR §180.142 (a)(8) 2

Cattle, fat 0.2 0.3 Recodify as §180.142(a).

Cattle, kidney 2 4.0 Recodify as §180.142(a).

Cattle, meat 0.2 0.3 Recodify as §180.142(a).
Commodity Tolerance Listed

Under 40 CFR

§180.142 (ppm)

Reassessed

Tolerance (ppm)

Comment

[Corrected Commodity Definition]

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Cattle, meat

byproducts, except

kidney

0.2 0.3 Recodify as §180.142(a).

Egg 0.05 Revoke Category 3 of 40 CFR §180.6(a)(3) applies. 

Goat, fat 0.2 0.3 Recodify as §180.142(a).

Goat, kidney 2 4.0 Recodify as §180.142(a).

Goat, meat 0.2 0.3 Recodify as §180.142(a).

Goat, meat

byproducts, except

kidney

0.2 0.3 Recodify as §180.142(a).

Hog, fat 0.2 Revoke Category 3 of 40 CFR §180.6(a)(3) applies.

Hog, kidney 2

Hog, meat 0.2

Hog, meat

byproducts, except

kidney

0.2

Horse, fat 0.2 0.3 Recodify as §180.142(a).

Horse, kidney 2 4.0 Recodify as §180.142(a).

Horse, meat 0.2 0.3 Recodify as §180.142(a).

Horse, meat

byproducts, except

kidney

0.2 0.3 Recodify as §180.142(a).

Milk 0.1 0.05 Residues in milk increased linearly with dose;

therefore, the 0.05 ppm tolerance will be adequate

for the 1x dose level. Recodify as §180.142(a).

Poultry 0.05 Revoke Category 3 of 40 CFR §180.6(a)(3) applies.

Sheep, fat 0.2 0.2 Recodify as §180.142(a).

Sheep, kidney 2 2.0 Recodify as §180.142(a).

Sheep, meat 0.2 0.2 Recodify as §180.142(a).

Sheep, meat

byproducts, except

kidney

0.2 0.2 Recodify as §180.142(a).

Tolerance Listed Under 40 CFR §180.142 (a)(9) 2

Fish 1.0 Revoke The reassessed tolerance of 0.1 ppm at

§180.142(a)(6) will be recodified as §180.142(a).

There is no need for duplication of tolerances.

Tolerance Listed Under 40 CFR §180.142 (a)(10) 2

Raspberry 1.0 Revoke Although there is no indication that IR-4 or the Task

Force II is supporting a use on raspberries, it would

be covered by the 0.2 ppm tolerance in the Berries

group 13 at §180.142(a).
Commodity Tolerance Listed

Under 40 CFR

§180.142 (ppm)

Reassessed

Tolerance (ppm)

Comment

[Corrected Commodity Definition]

Page 95 of 304

Tolerance Listed Under 40 CFR §180.142 (a)(11) 3

Soybean, seed 0.02 0.02 Tolerance expired on 12/31/04. Residue data

support a permanent tolerance. If established,

recodify as §180.142(a).

Tolerance Listed Under 40 CFR §180.142 (a)(12) 2

Sugarcane bagasse 5 Revoke Sugarcane bagasse is no longer considered a

significant livestock feed item.

Sugarcane molasses 5 0.20 Maximum residue value is based on HAFT residues

of 0.015 ppm in/on sugarcane and a 7x

concentration factor for molasses. Recodify as

§180.142(a). Sugarcane, molasses

Milled fractions

derived from barley,

oats, rye, and wheat

to be ingested as

animal feed or

converted into animal

feed

2 Revoke Tolerances for direct and inadvertent residues of

2,4-D in barley, bran; rye, bran; and wheat, bran are

to be established under revised 40 CFR 180.142(a). 

Tolerances in other small grain processed products

are not necessary as residues do not concentrate

upon processing.

Tolerance Listed Under 40 CFR §180.142 (a)(13) 2

Sugarcane molasses 5 Revoke The sugarcane molasses reassessed tolerance at

§180.142(a)(12) will be recodifed as §180.142(a). 

Duplication of tolerances is not necessary.

Milled fractions

derived from barley,

oats, rye, and wheat

to be ingested as

animal feed or

converted into animal

feed

2 Revoke Tolerances for direct and inadvertent residues of

2,4-D in barley, bran; rye, bran; and wheat, bran are

to be established under revised 40 CFR 180.142(a). 

Tolerances in other small grain processed products

are not necessary as residues do not concentrate

upon processing.

Potable water 0.1 (N) Revoke OPP no longer establishes tolerances in drinking

water. EPA’s Office of Water has established an

MCL for 2,4-D at 0.07 ppm.

Tolerances Needed Under 40 CFR §180.142 (a); this list does not include recodifications, etc. from above

Almond hulls None 0.10 Almond, hulls

Aspirated grain

fractions

None 40 Based on HAFT residues of 0.038 ppm for corn

grain and a 39x concentration factor, maximum

expected residues would be 1.48 ppm in aspirated

grain fractions (AGF) derived from corn grain. 

Based on HAFT residues of 3.24 ppm for wheat

grain and a 11.2x concentration factor, maximum

expected residues would be 36.3 ppm in AGF

derived from wheat grain. 

As sorghum and soybeans uses are early-season

uses, residue data on AGF were not generated for

these crops. Establish tolerance in AGF at 40 ppm.
Commodity Tolerance Listed

Under 40 CFR

§180.142 (ppm)

Reassessed

Tolerance (ppm)

Comment

[Corrected Commodity Definition]

Page 96 of 304

Barley, hay None TBD Data for wheat straw were translated to barley

straw. Required wheat wheat hay data will be

translated to barley hay. Barley, straw None 50

Barley, bran None 4.0 Data for wheat bran were translated to barley bran.

Millet, hay None TBD Required wheat wheat hay data will be translated to

millet hay.

Oat, hay None TBD Data for wheat straw were translated to oat straw.

Required wheat wheat hay data will be translated to

oat hay. Oat, straw -- 50

Rice, hulls None 2.0 Maximum residue value is based on HAFT residues

of 0.425 ppm in/on rice grain and a 3.3x

concentration factor for hulls.

Rye, straw None 50 Data for wheat straw were translated to rye straw.

Rye, bran None 4.0 Data for wheat bran were translated to rye bran.

Soybean, forage None 0.02 Adequate residue data are available to support

permanent tolerances on soybean commodities. Soybean, hay None 2.0

Soybean, seed None 0.02

Wheat, hay None TBD Data are required on wheat hay

Wheat, straw None 50

Wheat, bran None 4.0 Maximum residue value is based on HAFT residues

of 1.08 ppm in/on wheat grain (14-day PHI) and a

3.6x concentration factor for bran.

Tolerance Listed Under 40 CFR §180.142 (b) 5

Wild rice 0.1 0.05 Tolerance expires 12/31/05. Adequate data are

available to establish a permanent tolerance with a

regional registration to be recodified as §180.142(c)

for Rice, wild, grain at 0.05 ppm.

Tolerance Needed Under 40 CFR §180.142 (c) 6

Rice, wild, grain None 0.05 regional tolerance with use restricted to MN

Tolerances Needed Under 40 CFR §180.142 (d) 7

Commodities and

crop groups currently

listed under paragraph

(a)(3)

0.1 (N) NA See comments listed under §180.142(a)(3)

1 Maximum residue of treated RAC sample(s) following application of 2,4-D formulations according to use patterns

the Task Force II registrants intend to support for reregistration. 2 This subparagraph will be deleted and tolerances recodified under revised paragraph (a). 3 TBD = To be determined. Reassessment of tolerances(s) cannot be made at this time because additional data are

required. 4 Tolerances listed under §180.142 (a)(3) for inadvertent residues will be recodified as either §180.142(a) or

§180.142(d). 5 This paragraph will be reserved for future time-limited tolerances under Section 18 Emergency Exemptions. 6 Tolerances with regional use registration.
Page 97 of 304

7 Paragraph (d) will contain tolerances for inadvertent residues (e.g., residues in irrigated crops) only, i.e., there is no

registration for direct use in the U.S. If residues may result inadvertently as well as intentionally (direct, labeled

treatment), the tolerance is codified at §180.142(a)

3. Codex Harmonization

The Codex Alimentarius Commission has established several maximum residue limits (MRLs)

for residues of 2,4-D in/on various plant and animal commodities. The Codex MRLs are expressed in

terms of 2,4-D per se. The expression of residues for Codex MRLs and U.S. tolerances is

harmonized. A numerical comparison of the Codex MRLs and the corresponding reassessed U.S.

tolerances is presented in Table 39.

Table 39. Codex MRLs and applicable U.S. tolerances for 2,4-D. Recommendations for

compatibility are based on conclusions following reassessment of U.S. tolerances

Codex

Reassessed U.S. Tolerance,

ppm

Recommendation And Comments

Commodity, As Defined MRL

(mg/kg)

Barley 0.5 2.0

Blackberries 0.1 0.20 U.S. tolerance for Berries group 13

Citrus fruits 2.0 3.0

Eggs 0.05 (*) Revoked

Maize 0.05 (*) 0.05

Meat (from mammals other

than marine mammals) 0.05 (*) 0.30 Meat, fat, and mbyp except kidney

4.0 Kidney

Milk products 0.05 (*) 0.05

Milks 0.05 (*) 0.05

Oats 0.5 2.0

Potato 0.2 0.40

Raspberries, Red, Black 0.1 0.20 U.S. tolerance for Berries group 13

Rice 0.05 (*) 0.50

Rye 0.5 2.0

Sorghum 0.05 (*) 0.20 Forage, grain, and stover=0.2

Vaccinium berries, including

Bearberry 0.1 0.20 U.S. tolerance for Berries group 13

Wheat 0.5 2.0

(*) = At or about the limit of detection.

4. Residue Analytical Methods - Plants and Livestock (GLN 860.1340) 

For the purpose of reregistration, adequate methods are available for data collection and the

enforcement of plant commodity tolerances. The Pesticide Analytical Manual (PAM) Vol. II lists

three GC methods (designated as Methods A, B, and C) with microcoulometric detection and one GC
Page 98 of 304

method (designated as Method D) with electron capture detection (ECD). In a letter dated September

3, 1993 (CBRS No. 12270, DP Barcode D193335, 9/3/93, W. Smith), Task Force II indicated that the

enforcement methods currently listed in PAM Vol. II are unsuitable for determining residues of 2,4-D

in wheat and poultry commodities.

Plant Commodities: Task Force II submitted an adequate proposed GC/ECD enforcement method for

plants (designated as EN-CAS Method No. ENC-2/93) which has been independently validated. 

Adequate radiovalidation data have been submitted and evaluated for the proposed enforcement

method using samples from the wheat metabolism study. The proposed enforcement method or

modifications of the enforcement method were used for data collection purposes.

Livestock Commodities: Task Force II submitted two separate (but essentially comparable) proposed

enforcement methods (GC/ECD) for determination of 2,4-D in livestock commodities. Adequate

radiovalidation data have been submitted for the method using samples of fat, kidney, and milk from

the goat metabolism study and samples of eggs from the poultry metabolism study. The Agency

concluded that the methods are adequate provided the registrants satisfy the following requests: (i)

submit a revised method which combines the two methods into a single method; (ii) delete from the

method all references to the use of diazomethane as a derivatizing agent; and (iii) provide complete

raw data and sample calculations (including chromatograms showing peak areas, external standard

linearity curves and associated data, standard calculations, etc.). Once an adequate revised method is

submitted, the Agency will evaluate the tolerance method validation. Recently, it has been

determined that the technology to generate diazomethane has advanced such that it is no longer

considered to be a dangerous procedure; as a result, the use of diazomethane as a derivatizing agent is

now considered acceptable.

E. Regulatory Rationale

The following is a summary of the rationale for managing risks associated with the use of 2,4-

D. Where labeling revisions are warranted, specific language is set forth in the summary tables of

Section V of this document.

1. Human Health Risk Management

a. Residential Risk

1) Residential risk summary

A Margin of Exposure (MOE) of 1000 (10x for interspecies extrapolation, 10x for intraspecies

variation, and 10x database uncertainty factor) is considered adequately protective for this assessment

of residential risks. Residential handler risks are not of concern. All MOEs for post-application, oral

exposure to children from playing on treated lawns meet or exceed 1000; therefore, post-application

exposure to children is not of concern. Likewise, all adult acute/short term MOEs meet or exceed

1000, so post-application exposure is not of concern for adults.
Page 99 of 304

As discussed below, potential risks were identified to individuals who swim in water treated

with 2,4-D. Although the risk assessment is likely to be conservative, mitigation measures will be

required. 

2) Residential Post-application Mitigation

For residential, post-application exposures, when the calculated MOE of 1000 based on

modeling is considered in conjunction with biomonitoring results, it is clear that the modeled shortterm risks from post-application exposure are upper bound estimates. At one day post-treatment, the

MOEs for the volunteers who wore shorts and no shoes ranged from 1400 to 35000 with the lowest

MOE corresponding to the volunteer who removed his shirt during the exposure period. The MOEs

for the remaining volunteers ranged from 24000 to 37000. The Agency has concluded that no

further mitigation is needed for residential post-application exposures.

3) Residential Swimmer Mitigation

The acute MSWC of 9.8 ppm for exposures to 2,4-D acid or amine is greater than the proposed

maximum application rate of 4.0 ppm, therefore, acute exposures to acid or amine are not of concern.

The MSWC of 3.6 ppm for short-term exposures to acid or amine is also not of concern because

some dissipation or dispersion is likely to occur which would cause the 7-day average of 2,4-D

concentrations to be less than 3.6 ppm. Dissipation studies submitted to the Agency indicated that

the half lives following pond and lake liquid treatments ranged from 3.2 days to 27.8 days which

yield 7 day average concentrations of 1.9 ppm when the half life equals 3.2 days, to 3.6 ppm when the

half life equals 27.8 days. 

The MSWCs for 2,4-D BEE are less than the master label application rate of 4 ppm, but they

are unlikely to be of concern for the following reasons: 

C 2,4-D BEE degrades rapidly by abiotic hydrolysis in sterile water to form 2,4-D acid

particularly when the pH is 7.5 or above. 

C 2,4-D BEE degrades to 2,4-D acid by microbial hydrolysis with an average half life of 2.6 +

1.8 hours at a bacterial concentration of 5 x 10-8 organisms per liter. Therefore, degradation of 2,4-D

BEE to 2,4-D under typical environmental conditions will be rapid leading to significantly lower risk

estimates because the 2,4-D acid has a lower rate of dermal absorption.

C Modeling predicts direct water application of 2,4-D BEE will yield surface water concentrations

of 2,4-D BEE concentrations in the Agency standard pond of 624 ug/L for peak (24 hour average), 30

ug/L for the 21-day average, and 10 ug/L for the 60-day average. 

C The existing label rates for 2,4-D BEE products are also lower than the master label rate.
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Although the risk characterization above suggests that the risk estimates are conservative, a 24

hour post-application restriction on swimming is necessary to ensure the safety of children swimming

in water treated with 2,4-D BEE.

b. Aggregate Risk

The Food Quality Protection Act amendments to the Federal Food, Drug, and Cosmetic Act

(FFDCA, Section 408(b)(2)(A)(ii)) require “that there is a reasonable certainty that no harm will

result from aggregate exposure to pesticide chemical residue, including all anticipated dietary

exposures and other exposures for which there is reliable information.” Aggregate exposure will

typically include exposures from food, drinking water, residential uses of a pesticide, and other nonoccupational sources of exposure.

1) Aggregate Risk Summary

For 2,4-D, EPA conducted acute, short-term, and chronic aggregate risk assessments using the

reduced maximum application rate for residential turf (1.5 lbs ae/A). The aggregate risk assessment

compares the Drinking Water Level of Comparison (DWLOC) for each scenario with the appropriate

Estimated Drinking Water Concentration (EDWC) for the pesticide. The DWLOC is the maximum

concentration in drinking water which, when considered together with food, and, if appropriate,

residential exposure, does not exceed EPA’s level of concern. Generally, EDWCs that are less than

the corresponding DWLOC are not of concern to the Agency. 

It is important to note that the MCL for 2,4-D, established by EPA’s Office of Water under the

Safe Drinking Water Act (SDWA), is 70 ug/L. To minimize the possibility that direct aquatic

applications will result in drinking water concentrations in excess of the MCL, the Agency has

worked with the 2,4-D Task Force and water quality specialists to develop appropriate label

requirements for 2,4-D products registered for use to control aquatic weeds. 

2) Acute Aggregate Risk 

DWLOC Approach

Acute DWLOCs were calculated based upon acute dietary exposures. Acute residential

exposures from swimming in treated water bodies or playing on treated turf were not included

because exposures are unlikely to co-occur with acute dietary exposures. The acute DWLOCs are

range from 432 to 1932 with the most sensitive population being females 13 to 49 years old. The

EDWCs of 118 ug/liter for surface water and 15 ug/liter for groundwater are substantially less than

the DWLOCs which means that the risks are not of concern. 

Forward Calculation Approach

Acute aggregate risks were assessed by directly combining acute food exposures and estimates

of acute water exposures. The acute aggregate risks and are not of concern because they are less than

100 percent of the aPAD. The highest risks (58 percent of the aPAD) are for females 13-49 years old

because these risks are based upon the lower NOAEL of 25 mg/kg/day from a developmental study in
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rats. Whereas, estimates of other population groups are based on a NOAEL of 67 mg/kg/day from an

acute neurotoxicity study in rats. 

3) Short-term Aggregate Risk

DWLOC Approach

Short-term aggregate risks assessments were conducted by calculating DWLOCs based upon

short-term turf exposures, chronic food exposures and short-term endpoints. Short-term exposures

from swimming in treated water bodies were not included because these exposures represent high-end

unlikely scenarios. The short-term DWLOCs were calculated only for females 13-49 and children 1-

6 because these population subgroups have the highest exposure and estimates calculated for these

groups are protective of the other subgroups. The DWLOCs range from 24 to 36 ug/liter. The

EDWCs range from 15 to 23 ug/liter. Since the DWLOCs are all greater than the EDWCs, the short

term risks are not of concern.

Forward Calculation Approach

Short-term aggregate risks were assessed by aggregating short-term turf exposures, chronic

food exposures and chronic water exposures. Short-term aggregate risk were calculated only for

females 13-49 and children 1-6 because these population subgroups have the highest exposure and

estimates calculated for these groups are protective of the other subgroups. The short-term aggregate

MOEs indicate that the short term risks are not of concern because the MOEs equal or exceed the

target MOE of 1000.

4) Chronic (Non-Cancer) Aggregate Risk

DWLOC Approach

Chronic DWLOCs were calculated based upon chronic dietary exposures. As there are no

chronic residential exposures, residential exposures were not included in the chronic DWLOC

calculations. The chronic DWLOCs are 46 ug/L or greater with the most sensitive populations being

infants and children. The EDWCs, which range from 1.5 to 23 ug/L, are less than the DWLOCs

which means that the risks are not of concern. It should be noted that the master label indicates that

potable water consumption from a treated water body cannot begin until the 2,4-D concentration is 70

ug/L or below, therefore an annual average exposure at the MCL of 70 ug/L would not occur because

dissipation would reduce the initial concentration of 70 ug/L to an annual average concentration of 11

ug/L.

Forward Calculation Approach

Chronic aggregate risks were assessed by aggregating chronic food exposures and chronic

water exposures. The chronic aggregate risks are not of concern because they are less than 100

percent of the cPAD. The highest risks (38 percent of the cPAD) are for children 1-2 years old.
Page 102 of 304

5) Aggregate Risk Mitigation

 Given the reduced maximum application rate to residential lawns (1.5 lbs ae/A), the highest

aggregate risks are the risks from short-term exposures, which include the turf exposure scenarios. 

For the most sensitive subpopulation (females 13-49) these risks meet the target MOE of 1000 and

the turf exposure is the risk driver as it contributes 96 percent of the risk. 

Whereas calculated risks just meet the Agency’s target MOE, it is important to note that the turf

exposure estimate is based upon modeling and is greater than exposure measurements obtained from

biomonitoring. As described in the human health assessment, the results of a biomonitoring study

were used to calculated MOEs by assuming that all of the urinary 2,4-D measured in the 96 hours

after the exposure period was the result of the turf exposure. This assumption is protective because

2,4-D exposures due to inhalation and due to food and water ingestion would be counted as dermal

exposure. The biomonitoring results were adjusted by a factor of two to account for the SOP

assumption of two hours of daily exposure vs one hour of exposure during the study, and a factor of

1.7 to account for an application rate of 1.5 lbs ae/acre vs 0.88 lb ae/acre applied during the study. At

one day post-treatment, the MOEs for the volunteers who wore shorts and no shoes ranged from 1400

to 35000 with the lowest MOE corresponding to the volunteer who removed his shirt during the

exposure period. The MOEs for the remaining volunteers ranged from 24000 to 37000. If the

calculated MOE of 1000 based on modeling is considered in conjunction with the MOE calculated

based on biomonitoring results, it is clear that the modeled short-term risks are upper bound

estimates. The Agency has concluded that aggregate risks from acute, short-term and chronic

exposures are not of concern. No further mitigation beyond reducing the maximum application rate

from 2.0 to 1.5 lbs/ae per acre is needed.

c. Occupational Risk Mitigation

1) Handler Risk Mitigation

With the exception of mixing/loading wettable powder, the short-term and intermediate-term

Margin of Exposure estimates (MOEs) exceed 100 with baseline attire (i.e., long-sleeved shirt, long

pants, shoes plus socks) or single layer attire (i.e., long-sleeved shirt, long pants, shoes plus socks,

gloves) and are not of concern. The MOEs for handling wettable powder are acceptable with

engineering controls (i.e. water soluble bags). Water soluble bags will be required for wettable

powder formulations. 

2) Post-application Risk Mitigation

All short- and intermediate-term MOEs are above 100 on day zero. All occupational

postapplication risk scenarios are below EPA’s level of concern. Products containing 2,4-D salt and

ester forms as active ingredient with Worker Protection Standard (WPS) uses will require a re-entry

interval (REI) of 12 hours. Because of acute eye irritation concerns, products containing 2,4-D acid

and amine forms with WPS uses will require a REI of 48 hours and protective eyewear. The

requirements for individual products will be finalized based on product-specific chemistry and acute
Page 103 of 304

toxicity review. The exposure reduction program implemented in 1992 will be replaced with the

personal protective equipment described in section V.D. of this document. 

2. Environmental Risk Mitigation 

The Agency has considered available information on 2,4-D’s toxicity, use areas, usage, fate

properties, application methods, and formulations in calculating ecological risks. The resulting

assessment suggests that the use of 2,4-D for aquatic weed control presents risk to aquatic organisms,

while 2,4-D use on terrestrial sites presents greater potential risks to small mammals, birds, and nontarget terrestrial plants, than to other plants and animals. 

a. Birds

Acute Risk

Whereas the assessment of risk to birds from the terrestrial use of 2,4-D suggests risks of

concern, the assessed exposures to 2,4-D are likely conservative in the following ways. Currently,

Agency models do not account for the uptake of 2,4-D by plants and therefore assume that all nondissipated pesticide applied to the field is present for exposure to organisms. In fact, many pesticides,

including 2,4-D, are systemic and are absorbed by plants in the field and therefore, the current

approach may overestimate the amount of 2,4-D available for exposure in terrestrial and aquatic

systems. 

For non-granular spray application, the highest acute avian RQ (3.5) was from the cranberry

use-site scenario, for birds feeding on short grass. That assessment was based on a maximum

application rate of 4 lbs ae/acre; however, the average application rate is 1.83 lbs ae/acre (see the

Agency’s quantitative use assessment). If the modeled application rate was reduced to 1.83 lbs

ae/acre for cranberries, and an assumption made that the resulting EEC will be reduced linearly, the

RQ would be 1.6. 

To determine the hazard associated with acute exposures to birds, the assessment has relied on

two types of data, a suite of dietary studies and a suite of gavage studies. For avian acute exposures,

the dietary studies result in non-definitive endpoints which are not appropriate for estimating risk. 

Therefore, the assessment has relied on the gavage studies to estimate avian acute risks. The Agency

recognizes that this approach may overestimate risk to birds due to the fact that birds would not

typically be expected to consume 2,4-D in this manner.

Chronic Risk

Potential chronic risks to birds is limited to the following use sites: non-cropland, forest,

asparagus, and cranberry. The RQs for these sites range from one to slightly above one. Further

characterization of these use sites by evaluating average application rates versus maximum

application rates lower these RQs to below the LOCs.

Given the conservative assumptions in both exposure scenarios and hazard determinations, the

Agency finds that the acute and chronic risks to birds from 2,4-D exposure are not of concern.
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b. Mammals

Acute risk

All of the calculated RQs for mammalian acute risk for the non-granular use of 2,4-D were

based on maximum labeled application rates. The EPA’s quantitative use assessment (EPA QUA)

suggests that the average application rates for many crops are considerably less than the modeled

maximum application rates. For non-granular spray application mammalian acute concerns, the

highest RQ was 1.72 for use on asparagus for small mammals feeding on short grass based on a

maximum application rate of 2 lbs ae/A applied two times a year; however, the average application

rate was only 1.10 lbs ae/A (EPA QUA). If the modeled application rate was reduced to the reported

average application rate of 1.10 lbs ae/A for asparagus, the RQ would be 1.08 which is still above the

acute LOC of 0.5. However, asparagus is representative of a minor 2,4-D use, and risk to mammals

from use of 2,4-D on asparagus would be minimal, given that fact.

To add context to the acute mammalian assessment, the effect of assuming an average

application rate was determined. Major 2,4-D crops include pasture/rangeland, turf, wheat, corn, and

soybeans. For pasture/rangeland, the highest acute RQ was 0.86 for small mammals feeding on short

grass based on a maximum application rate of 4 lbs ae/A. However, the average application rate was

only 0.62 lbs ae/A (BEAD QUA). If the modeled application rate was reduced to 0.62 lbs ae/A for

pasture/rangeland, the resulting RQ is 0.31 which is below the acute LOC, but above the restricted

use LOC of 0.2. Similar trends are noted for other major use sites. 

Although the calculated RQ values still exceed the Agency’s level of concern when average

applications rates are considered, the Agency has concluded that the benefits from 2,4-D use

(including control of invasive and noxious weed species), taken together with the low toxicity of 2,4-

D to humans, outweigh the concerns of toxicity to small mammals. No additional mitigation steps

will be taken.

Chronic risk

Calculated chronic risks to mammals were greatest for small herbivores/insectivores. For 15 g

mammalian herbivores/insectivores, chronic RQs based on maximum residues and mean residues

ranged from <1 to 200 and <1 to 70, respectively. For major use sites, including rangeland/pasture,

RQs were approximately 100. These chronic risk estimates are likely conservative as described

below.

The chronic RQs calculated for mammalian herbivores/insectivores are based on conservative

estimates of exposure that are not likely to occur in nature. In the example of pasture/rangeland, the

chronic RQ of approximately 100 for maximum residues (35 for mean residues) was calculated based

on an application rate of 2 lbs ae/A applied twice per year, at a 30 day interval. However, the EPA

has determined that the average application rate on pasture/rangeland is only 0.62 lbs ae/A (EPA

QUA). Moreover, information from several of the Agency’s state contacts indicate that a once per

year application of less than 1 lb ae/A is typical (personal communications). As the typical rate is

approximately 25% of the assessed rate, use of the typical rate would be expected to decrease the RQ

for the pasture/rangeland scenario approximately four-fold, to approximately 25 for maximum

residues and 9 for mean residues.

A second example of the conservative assumptions included in the assessment of exposure to

mammalian herbivores/insectivores is the assumption that 100% of the long term diet is relegated to
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single food types foraged only from treated fields. The assumption of 100% diet from a single food

type may be realistic for acute exposures, but diets are likely to be more variable over longer periods

of time. The risk assessment assumed that 100% of the small mammals’ diet consists of short

grasses. Several published reports suggest that actual diets of small mammals are more varied, and

would likely include invertebrates, worms, fungi, and seeds, in addition to plant matter. 

Given the conservative assumptions in the exposure scenarios, the Agency finds that the risks

identified in the risk assessment are likely to overestimate actual risks to mammals from 2,4-D

applications. Based on information about average application rates and dietary patterns as described

above, the Agency has concluded that actual 2,4-D exposures to mammals are likely to be

significantly lower than those assessed but may still be above the chronic LOC for this screening

level assessment. However, the Agency has concluded that the benefits from 2,4-D use (including

control of invasive and noxious weed species), taken together with the low toxicity of 2,4-D to

humans, outweigh the concerns of toxicity to small mammals. No additional mitigation is being

required at this time.

c. Aquatic Organisms 

Whereas the assessment of risk to aquatic organisms suggests risks of concern, the assessed

exposures to 2,4-D are likely conservative as follows. Whereas the maximum labeled target

concentration for control of aquatic weeds is 4 ppm, the typical target concentration is 2 ppm. A rate

of 4 ppm is reserved for spot-treating new aquatic weed stands and hybrid weed species that tend to

be less susceptible to 2,4-D. Per the product label, re-application of 2,4-D can occur after 21 days. 

In the current assessment, the risks to aquatic organisms were estimated based on a 2,4-D

application that resulted in a whole-reservoir concentration of 4 ppm. Treating 100% of the water

body would likely result in a large amount of decaying plant life, thereby creating an oxygen-depleted

environment that would most likely result in fish kills. To avoid that scenario, the current 2,4-D label

advises that the applicator avoid treating more than 50% of a water body in a 21-day period. In actual

practice, aquatic weeds that 2,4-D controls tend to grow near the shore of lakes, ponds, and

reservoirs. As a result, generally a maximum of 20-30% of a water body is treated in a single

application. Applying the typical rate of 2 ppm, and taking into account a typical maximum treated

area of 30%, would decrease calculated RQs by approximately 6-fold. 

While noting the potential risks to aquatic organisms from the direct application of 2,4-D for the

control of aquatic weeds identified above, it is important to note the benefits gained through the direct

application of 2,4-D to aquatic bodies, for the control of invasive species. The U.S Army Corps of

Engineers (USACE) and state agencies have identified 2,4-D as an important tool for protecting water

bodies from the invasion and establishment of some species of exotic nuisance vegetation. 2,4-D has

a reputation as a selective and economical means to remove invasive plants, enhance the growth and

recovery of desirable native vegetation, restore water quality, reduce sedimentation rates in reservoirs,

and improve fish and wildlife habitat. 2,4-D products are used to control invasive weeds, such as

Eurasian water milfoil (Myriophyllum spicatum) in the northern tier states and water hyacinth

(Eichhornia crassipes) in the Gulf Coast states. Effective control of these plants can benefit public

health with respect to reducing levels of mosquito habitat. In addition, according to USACE, no other

product (or alternative technique) can control these plants in a more cost-effective manner (K.

Getsinger, USACE, Public Comment; Docket ID# OPP-2004-0167-0053).
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Given the typical application rates and treatment areas, and considering the beneficial aspects of

using 2,4-D to control invasive plant species, the Agency concludes that the benefits from direct

aquatic use of 2,4-D outweigh the risk concerns for aquatic organisms. No additional mitigation

measures will be required at this time to address risk to aquatic organisms.

d. Non-target Insects

Risk to non-target insects do not exceed the Agency’s level of concern. Available data from a

honey bee acute toxicity study indicated that technical 2,4-D is practically non-toxic to the honey bee. 

The potential for 2,4-D and its salts and esters to pose risk to pollinators and other beneficial insects is

expected to be minimal.

e. Non-target Terrestrial Plants 

Estimated RQs exceeded acute LOCs for both non-endangered and endangered terrestrial plants

for non-granular and granular uses at many use sites. Consideration of average application rates did

not result in exposure below LOCs. However, the exposure estimates used to develop the RQs were

likely conservative, as follows. 

In the exposure calculation for non-target aquatic plants and terrestrial plants in intermittently

flooded areas, the major contributor is run-off from the application site. The run-off and leaching

vulnerability schemes used in this assessment incorporate several conservative assumptions which are

fully discussed in the ecological risk assessment. Also, it is likely that farm management practices

would be in place to limit run-off, as run-off events are detrimental to the farm as a whole for reasons

other than pesticide damage.

Whereas the risk assessments are likely conservative as described above, the Agency is

concerned about the risk to non-target terrestrial plants from drift of 2,4-D during application. To

address that concern, the Agency is implementing spray drift controls that will decrease the risk that

2,4-D will drift onto non-target plants.

f. Summary of Environmental Risk Mitigation

Characterization of the risks identified in the Agency’s screening level risk assessment suggests

that risks from drift onto non-target plants exceeds the Agency’s level of concern. The Agency is

implementing spray drift controls that will decrease the risk that 2,4-D will drift onto non-target

plants.

F. Other Labeling Requirements

In order to be eligible for reregistration, various use and safety information will be included in

the labeling of all end-use products containing 2,4-D. For the specific labeling statements and a list of

outstanding data, refer to Section V of this RED document. 

1. Endangered Species Considerations
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The Agency has developed the Endangered Species Protection Program to identify pesticides

whose use may cause adverse impacts on endangered and threatened species, and to implement

mitigation measures that address these impacts. The Endangered Species Act requires federal

agencies to ensure that their actions are not likely to jeopardize listed species or adversely modify

designated critical habitat. To analyze the potential of registered pesticide uses that may affect any

particular species, EPA uses basic toxicity and exposure data and considers ecological parameters,

pesticide use information, geographic relationship between specific pesticide uses and species

locations, and biological requirements and behavioral aspects of the particular species. Based on

EPA’s screening level assessment for 2,4-D, RQs exceed levels of concern for mammals, birds,

aquatic plants, and terrestrial plants. However, these findings are based solely on EPA’s screening

level assessment and do not constitute “may affect” findings under the ESA. The Agency is requiring

additional data to further characterize and refine its ecological and endangered species risk

assessments. The 2,4-D Task Force has submitted a limited endangered species assessment on

several crops for the Agency’s consideration. This assessment was generated using the FIFRA

Endangered Species Task Force (FESTF) integrated management system (IMS). 

2. Spray Drift Management

The Agency has been working closely with stakeholders to develop improved approaches for

mitigating risks to human health and the environment from pesticide spray and dust drift. As part of

the reregistration process, we will continue to work with all interested parties on this important issue.

From its assessment of 2,4-D, as summarized in this document, the Agency concludes that

certain drift mitigation measures are needed to address the risks from off-target drift for 2,4-D. Label

statements implementing these measures are listed in the "spray drift management" section of the

Labeling Changes Summary Table in section V.D. of this RED document. In the future, 2,4-D

product labels may need to be revised to include additional or different drift label statements.

3. Consumer Labeling Initiative

The Consumer Labeling Initiative (CLI) is an effort among federal, state, and local government

agencies, industry, environmental groups, and other interested parties working to improve product

labels on residential pesticides in order to improve consumer understanding and compliance of

consumer labels. The CLI Work Group of the Pesticide Program Dialogue Committee (PPDC) is

working to revise consumer labels. In addition to the labeling changes presented in this RED, the

Agency will leave open the possibility that changes to residential product labeling may occur as the

result of the PPDC CLI. 
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V. What Registrants Need To Do

For 2,4-D technical grade active ingredient products, registrants need

to submit the following items.

Within 90 days from receipt of the generic data call-in (DCI): 

(1) completed response forms to the generic DCI (i.e., DCI response form and

requirements status and registrant’s response form); and

(2) submit any time extension and/or waiver requests with a full written

justification.

Within the time limit specified in the generic DCI:

(1) cite any existing generic data which address data requirements or submit new

generic data responding to the DCI.

Please contact Katie Hall at (703) 308-0166 with questions regarding generic reregistration

and/or the DCI. All materials submitted in response to the generic DCI should be addressed:

By US mail: By express or courier service:

Document Processing Desk (DCI/SRRD) Document Processing Desk (DCI/SRRD)

Katie Hall Katie Hall

US EPA (7508C) Office of Pesticide Programs (7508C)

1200 Pennsylvania Ave., NW Room 604, Crystal Mall 2

Washington, DC 20460 1801 S. Bell Street

Arlington, VA 22202 -4501

For products containing the active ingredient 2,4-D registrants need to

submit the following items for each product.

Within 90 days from the receipt of the product-specific data call-in (PDCI):

(1) completed response forms to the PDCI (i.e., PDCI response form and

requirements status and registrant’s response form); and

(2) submit any time extension or waiver requests with a full written justification.

Within eight months from the receipt of the PDCI:

(1) two copies of the confidential statement of formula (EPA Form 8570-4); 
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(2) a completed original application for reregistration (EPA Form 8570-1). 

Indicate on the form that it is an “application for reregistration”;

(3) five copies of the draft label incorporating all label amendments outlined in

Table 40 of this document;

(4) a completed form certifying compliance with data compensation requirements

(EPA Form 8570-34);

(5) if applicable, a completed form certifying compliance with cost share offer

requirements (EPA Form 8570-32); and

(6) the product-specific data responding to the PDCI.

Please contact Moana Appleyard at (703) 308-8175 with questions regarding product

reregistration and/or the PDCI. All materials submitted in response to the PDCI should be addressed:

By US mail: By express or courier service only:

Document Processing Desk (PDCI/PRB) Document Processing Desk (PDCI/PRB)

Moana Appleyard Moana Appleyard 

US EPA (7508C) Office of Pesticide Programs (7508C)

1200 Pennsylvania Ave., NW Room 266A, Crystal Mall 2

Washington, DC 20460 1801 Bell Street

Arlington, VA 22202

A. Manufacturing Use Products

1. Additional Generic Data Requirements

The generic data base supporting the reregistration of 2,4-D for eligible uses has been

reviewed and determined to be substantially complete. However the following data requirements are

necessary to confirm the reregistration eligibility decision documented in this RED. 

Table 40. Data Requirements for the Reregistration Eligibility Decision for 2,4-D

Guideline Study Name New OPPTS

Guideline No.

Old

Guideline

No.

Environmental Fate and Effects Data Requirements

Aquatic field dissipation studies (Behavior of 2,4-D BEE under acidic to neutral

aquatic conditions in a water/sediment system)

835.6200 164-2

Laboratory volatility study (2,4-D IPE) 835.1410 163-2

Terrestrial field dissipation studies (2,4-D IPA, 2,4-D TIPA, 2,4-D DEA, 2,4-D

BEE)

835.6100 164-1
Guideline Study Name New OPPTS

Guideline No.

Old

Guideline

No.

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Aquatic field dissipation studies in a rice use scenario (2,4-D IPA, 2,4-D TIPA, 2-

4-D DEA)

835.6200 164-2

Aquatic field dissipation studies in an aquatic weed control scenario (2,4-D IPA,

2,4-D TIPA, 2-4-D DEA)

835.6200 164-2

Forest field dissipation studies (2,4-D IPA, 2,4-D TIPA, 2,4-D BEE, and 2,4-D

DEA)

835.6300 164-3

Fish acute toxicity test, freshwater and marine with typical end-use product (TEP)

(2,4-D BEE)

850.1075 72-1

Oyster acute toxicity test with TEP (2,4-D BEE) 850.1025 72-3

Mysid acute toxicity test with TEP (2,4-D BEE) 850.1035 72-3

Penaid acute toxicity test with TEP (2,4-D BEE) 850.1045 72-3

Sediment and soil adsorption/desorption (2,4-D BEE granular formulation) 835.1230 163-1

Seedling Germination/Seedling Emergence

Vegetative Vigor

Non-target terrestrial plants - TEP representative testing from the acid and amine

salts group, and representative testing from the ester group. The test products

should include the most common and most active surfactants and adjuvants which

affect the toxicity of the product. The registrants should consult with the Agency

before finalizing which products to test. 

850.4225

850.4250

123-1(a)

123-1(b)

The registrant must provide information on the proximity of Federally listed

freshwater vascular plants, birds, mammals, and non-target terrestrial plants (there

are no listed estuarine/marine invertebrates) to the 2,4-D use sites. This

requirement may be satisfied in one of three ways: 1) having membership in the

FIFRA Endangered Species Task Force (Pesticide Registration [PR] Notice 2000-

2); 2) citing FIFRA Endangered Species Task Force data; or 3) independently

producing these data, provided the information is of sufficient quality to meet

FIFRA requirements. Registrants should consult with the Agency prior to

fulfilling this data requirement.

- -

Human Health Effects Data Requirements

Developmental neurotoxicity study 870.6300 83-6

Subchronic inhalation toxicity study (28-day) 870.3465 82-4

Repeat two-generation reproduction study (using the most recent Agency

protocol) addressing concerns for endocrine disruption (thyroid and

immunotoxicity measures)

870.3800 83-4

Product and Residue Chemistry Data Requirements

Crop field trials - wheat hay 860.1500 171-4k
Guideline Study Name New OPPTS

Guideline No.

Old

Guideline

No.

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Water, fish, and irrigated crops - irrigated crop studies in strawberries and sugar

beet roots and tops

860.1400 171-4f

Residue analytical method - revised enforcement method for determination of 2,4-

D in livestock commodities

860.1340 171-4c

Directions for Use 860.1200 171-3

Other Data Requirements

UV/Visible Absorption 830.7050 None

Droplet Size Spectrum 840.1100 201-1

Drift Field Evaluation 840.1200 202-1

The Agency is requiring that five recent batches of all technical products be

analyzed for 2,3,7,8-TCDD, 2,3,7,8-TCDF and their respective higher substituted

chlorinated congeners using validated analytical methods. The Agency specifies

that the manufacturers use the most current state-of-the art laboratory methods for

measuring 2,3,7,8-TCDD and TCDF at levels less than 1 part per trillion (EPA

Method 1613, Tetra- through Octa-Chlorinated Dioxins and Furans by Isotope

Dilution HRGC/HRMS). Because 1,2,3,7,8-PeCDD is equi-potent to 2,3,7,8-

TCDD in the TEF scheme, the Agency is adding this compound to our testing

requirements. 

- -

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. Registrants must review

previous data submissions to ensure that they meet current EPA acceptance criteria and if not, commit

to conduct new studies. If a registrant believes that previously submitted data meet current testing

standards, then the study MRID numbers should be cited according to the instructions in the

Requirement Status and Registrants Response Form provided for each product.

2. Labeling for End-Use Products

Labeling changes are necessary to implement the mitigation measures outlined in Section IV

above. Specific language to incorporate these changes is specified in Table 40.

C. Existing Stocks

Registrants may generally distribute and sell products bearing old labels/labeling for 12

months from the date of the issuance of this Reregistration Eligibility Decision document. Persons
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other than the registrant may generally distribute or sell such products for 24 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.
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D. Required Labeling Changes Summary TableIn order to be eligible for reregistration, all product labels must be amended to incorporate the risk mitigation measureIV. The following table describes how language on the labels should be amended.

Table 41: Summary of Labeling Changes for 2,4-D

Description Amended Labeling Language 

For all Manufacturing UseProducts

“Only for formulation into an herbicide or plant growth regulator for the following use(s)

[fill blank only with those uses that are being supported by MP registrant].”“Wettable powder formulations must be packaged in water-soluble packages.” 

One of these statements maybe added to a label to allowreformulation of the productfor a specific use or alladditional uses supported by aformulator or user group

“This product may be used to formulate products for specific use(s) not listed on the MPlabel if the formulator, user group, or grower has complied with U.S. EPA submissionrequirements regarding support of such use(s).”“This product may be used to formulate products for any additional use(s) not listed on theMP label if the formulator, user group, or grower has complied with U.S. EPA submissionrequirements regarding support of such use(s).”

Environmental HazardsStatements Required by theRED and Agency LabelPolicies

"This chemical is toxic to fish and aquatic invertebrates. Do not discharge effluent

containing this product into lakes, streams, ponds, estuaries, oceans, or other waters unlessin accordance with the requirements of a National Pollution Discharge Elimination System(NPDES) permit and the permitting authority has been notified in writing prior todischarge. Do not discharge effluent containing this product to sewer systems withoutpreviously notifying the local sewage treatment plant authority. For guidance contact yourState Water Board or Regional Office of the EPA."

End Use Products Intended for Occupational Use
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PPE RequirementsEstablished by the RED1for liquids, wettable powdersformulated in water-solublepackages, and waterdispersible granules

“Personal Protective Equipment (PPE)“Some materials that are chemical-resistant to this product are” (registrant inserts correct

chemical-resistant material). “If you want more options, follow the instructions forcategory” [registrant inserts A,B,C,D,E,F,G,or H] “on an EPA chemical-resistance

category selection chart."“All mixers, loaders, applicators, flaggers, and other handlers must wear:- long-sleeved shirt and long pants,- shoes and socks, plus- chemical resistant gloves, when applying postharvest dips or sprays to citrus, applying

with any handheld nozzle or equipment, mixing or loading, cleaning up spills or

equipment, or otherwise exposed to the concentrate.- chemical resistant apron when applying postharvest dips or sprays to citrus, mixing or

loading, cleaning up spills or equipment, or otherwise exposed to the concentrate.See engineering controls for additional requirements.”

PPE RequirementsEstablished by the RED1

for granularformulations

“Personal Protective Equipment (PPE)All loaders, applicators, and other handlers must wear:

- long-sleeved shirt and long pants,- shoes plus socks.”

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.”
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Engineering Controls for aerial applications

Enclosed Cockpits“Engineering Controls: Pilots must use an enclosed cockpit that meets the requirements listed in the WPS for

agricultural pesticides [40 CFR 170.240(d)(6)]”

Engineering Controls for wettable powderformulations packaged inwater-soluble packages

“Engineering Controls”“Water-soluble packets when used correctly qualify as a closed loading system under the

WPS. Mixers and loaders using water-soluble packets (1) must wear the PPE specifiedabove for mixers and loaders and (2) must be provided, have immediately available for usein an emergency, such as a broken package, spill, or equipment breakdown a NIOSHapproved dust mist filtering respirator with MSHA/NIOSH approval number prefix TC21C or a NIOSH-approved respirator with any N 2, R, P, or HE filter.”

User SafetyRecommendations

“User Safety RecommendationsUsers should wash hands before eating, drinking, chewing gum, using tobacco, or using thetoilet.Users should remove clothing/PPE immediately if pesticide gets inside. Then washthoroughly and put on clean clothing. If pesticide gets on skin, wash immediately withsoap and water.Users should remove PPE immediately after handling this product. Wash the outside ofgloves before removing. As soon as possible, wash thoroughly and change into clean

clothing.”
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Environmental HazardStatement for Terrestrial Uses

“This pesticide may be toxic to fish and aquatic invertebrates. Do not apply directly to

water, to areas where surface water is present, or to intertidal areas below the mean highwater mark except as noted on appropriate labels. Drift and runoff may be hazardous toaquatic organisms in water adjacent to treated areas. Do not contaminate water whendisposing of equipment wash waters or rinsate. This chemical has properties and characteristics associated with chemicals detected ingroundwater. The use of this chemical in areas where soils are permeable, particularlywhere the water table is shallow, may result in groundwater contamination. Applicationaround a cistern or well may result in contamination of drinking water or groundwater.” 

Environmental HazardStatement for products usedfor aquatic weed control

“Fish breathe dissolved oxygen in the water and decaying weeds also use oxygen. Whentreating continuous, dense weed masses, it may be appropriate to treat only part of theinfestation at a time. For example, apply the product in lanes separated by untreated stripsthat can be treated after vegetation in treated lanes has disintegrated. During the growingseason, weeds decompose in a 2 to 3 week period following treatment. Begin treatmentalong the shore and proceed outwards in bands to allow fish to move into untreated areas. Waters having limited and less dense weed infestations may not require partial treatments.” 

Restricted-Entry Interval forproducts containing withdirections for use within thescope of the WPS andcontaining 2,4-D acid or amineforms

“Do not enter or allow worker entry into treated areas during the restricted entry interval

(REI) of 48 hours.”

Restricted-Entry Interval forproducts containing withdirections for use within thescope of the WPS andcontaining 2,4-D salt or esterforms

“Do not enter or allow worker entry into treated areas during the restricted entry interval

(REI) of 12 hours.”
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Early Entry PersonalProtective Equipmentestablished by the RED forproducts containing 2,4-D acidor amine forms and with WPSuses

“PPE required for early entry to treated areas that is permitted under the Worker Protection

Standard and that involves contact with anything that has been treated, such as plants, soil,or water is:- coveralls,- chemical-resistant gloves made of any water-proof material,- shoes plus socks,- protective eyewear.”

Early Entry PersonalProtective Equipmentestablished by the RED forproducts containing 2,4-D saltor ester forms and with WPSuses

“PPE required for early entry to treated areas that is permitted under the Worker Protection

Standard and that involves contact with anything that has been treated, such as plants, soil,or water is:- coveralls,- chemical-resistant gloves made of any water-proof material,- shoes plus socks.”

Entry Restrictions for GranularFormulations with directionsfor use outside the scope of theWPS

“Do not enter or allow people (or pets) to enter the treated area until dusts have settled.” 
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Entry Restrictions for liquids,water-dispersible granules, andwettable powders formulatedin water-soluble packages withdirections for use outside thescope of the WPS

“Do not enter or allow people (or pets) to enter the treated area until sprays have dried.” 

General ApplicationRestrictions for productsprimarily intended foroccupational (professional) use

“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.”
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Use-Specific ApplicationRestrictions(Note: The maximumallowable application rate mustbe listed as pounds or gallonsof formulated product persurface acre, not just as poundsacid equivalent per surfaceacre.)

“Aquatic weed control”For all acids, salts, amines, and butoxyethanol ester forms used for aquatic weed control,

the following statements must appear on the product label:> “Ditchbank applicationPostemergence: Limited to 2 applications per season.Maximum of 2.0 lbs ae/acre per application.Minimum of 30 days between applications.Spot treatment permitted.Do not use on small canals with a flow rate less than 10 cubic feet per second (CFS) wherewater will be used for drinking purposes. CFS may be estimated by using the formulabelow. The approximate velocity needed for the calculation can be determined byobserving the length of time that it takes a floating object to travel a defined distance. Divide the distance (ft.) by the time (sec.) to estimate velocity (ft. per sec.). Repeat 3 timesand use the average to calculate CFS. Average Width (ft.) x Average Depth (ft.) x Average Velocity (ft. per sec.) = CFSFor ditchbank weeds:Do not allow boom spray to be directed onto water surface.Do not spray across stream to opposite bank. 
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Use-Specific ApplicationRestrictions(Note: The maximumallowable application rate mustbe listed as pounds or gallonsof formulated product persurface acre, not just as poundsacid equivalent per surfaceacre.)

For shoreline weeds:Allow no more than 2 foot overspray onto water.”> “Floating and Emergent WeedsMaximum of 4.0 lbs ae/surface acre per application.Limited to 2 applications per season. Minimum of 21 days between applications.Spot treatments are permitted.Apply to emergent aquatic weeds in ponds, lakes, reservoirs, marshes, bayous, drainage

ditches, non-irrigation canals, rivers, and streams that are quiescent or slow moving.Coordination and approval of local and state authorities may be required, either by letter ofagreement or issuance of special permits for aquatic applications.Water Use

1. Water for irrigation or sprays:A. If treated water is intended to be used only for crops or non-crop areas that are labled for

direct treatment with 2,4-D such as pastures, turf, or cereal grains, the treated water may beused to irrigate and/or mix sprays for these sites at anytime after the 2,4-D aquaticapplication.
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Use-Specific ApplicationRestrictions

B. Due to potential phytotoxicity considerations, the following restrictions are applicable:

If treated water is intended to be used to irrigate or mix sprays for plants grown in commercial nurseries and greenhouses; and other plants or crops that are not labeled fordirect treatment with 2,4-D, the water must not be used unless one of the followingrestrictions has been observed:i. A setback distance from functional water intake(s) of greater than or equal to 600 ft. wasused for the application, or,ii. A waiting period of 7 days from the time of application has elapsed, or,iii. An approved assay indicates that the 2,4-D concentration is 100 ppb (0.1 ppm) or less at

the water intake. Wait at least 3 days after application before initial sampling at waterintake.2. Drinking water (potable water):A. Consult with appropriate state or local water authorities before applying this product

to public waters. State or local agencies may require permits. The potable water userestrictions on this label are to ensure that consumption of water by the public is allowed

only when the concentration of 2,4-D in the water is less than the MCL (MaximumContaminant Level) of 70 ppb. Applicators should consider the unique characteristics of thetreated waters to assure that 2,4-D concentrations in potable water do not exceed 70 ppb atthe time of consumption.
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Use-Specific ApplicationRestrictions

B. For floating and emergent weed applications, the drinking water setback 

distance from functioning potable water intakes is greater than or equal to 600 ft.

C. If no setback distance of greater than or equal to 600 ft. is used for application, 

applicators or the authorizing organization must provide a drinking water notification priorto a 2,4-D application to the party responsible for public water supply or to individual

private water uses. Notification to the party responsible for a public water supply or toindividual private water users must be done in a manner to assure that the party is aware ofthe water use restrictions when this product is applied to potable water.The following is an example of a notification via posting, but other methods of notification

which convey the above restrictions may be used and may be required in some cases under

state or local law or as a condition of a permit.Example:Posting notification should be located every 250 feet including the shoreline of the treatedarea and up to 250 feet of shoreline past the application site to include immediate publicaccess points. Posting must include the day and time of application. Posting may beremoved if analysis of a sample collected at the intake 3 or more days following applicationshows that the concentration in the water is less than 70 ppb (100 ppb for irrigation or

sprays), or after 7 days following application, whichever occurs first.
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Use-Specific ApplicationRestrictions

Text of notification: Wait 7 days before diverting functioning surface water intakes

from the treated aquatic site to use as drinking water, irrigation, or sprays, unless water at

functioning drinking water intakes is tested at least 3 days after application and isdemonstrated by assay to contain not more than 70 ppb 2,4-D (100 ppb for irrigation orsprays). Application Date:_____ Time:______D. Following each application of this product, treated water must not be used for drinking water unless one of the following restrictions has been observed:

i. A setback distance from functional water intake(s) of greater than or equal to 600 ft. was

used for the application, or,ii. A waiting period of at least 7 days from the time of application has elapsed, or,

iii. An approved assay indicates that the 2,4-D concentration is 70 ppb (0.07 ppm) or less atthe water intake. Sampling for drinking water analysis should occur no sooner than 3 daysafter 2,4-D application. Analysis of samples must be completed by a laboratory that iscertified under the Safe Drinking Water Act to perform drinking water analysis using acurrently approved version of analytical Method Number 515, 555, other methods for 2,4-D as may be listed in Title 40 CFR, Part 141.24, or Method Number 4015 (immunoassay

of 2,4-D) from U.S. EPA Test Methods for Evaluating Solid Waste SW-846.E. Note: Existing potable water intakes that are no longer in use, such as those replacedby a connection to a municipal water system or a potable water well, are notconsidered to be functioning potable water intakes.
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Use-Specific ApplicationRestrictions

F. Drinking water setback distances do not apply to terrestrial applications of 2,4-D

adjacent to water bodies with potable water intakes.3. Swimming (2,4-D butoxyethanol ester only):A. Do not swim in treated water for a minimum of 24 hours after application.

B. Users must provide notification prior to performing a 2,4-D BEE application.Notification to the party responsible for the public swimming area or to individual privateusers must be done in a manner to assure that the party is aware of the water use swimmingrestrictions when this product is applied to water. The following is an example of anotification via posting, but other methods of notification which convey the aboverestrictions may be used and may be required in some cases under state or local law or as a

condition of a permit.Example:Posting notification should be located every 250 feet including the shoreline of the treatedarea and up to 250 feet of shoreline past the application site to include immediate publicaccess points.Text of Notification: Do not swim in treated water for a minimum of 24 hours afterapplication. Application Date: ______ Time: _____ .4. Except as stated above, there are no restrictions on using water from treated areas for

swimming, fishing, watering livestock or domestic purposes.”
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Use-Specific ApplicationRestrictions(Note: The maximumallowable application rate mustbe listed as pounds or gallonsof formulated product per acrefoot, not just as pounds acidequivalent per acre-foot.)

> “Submersed WeedsMaximum of 10.8 lbs ae/per acre-foot per application.Limited to 2 applications per season.Apply to aquatic weeds in ponds, lakes, reservoirs, marshes, bayous, drainage ditches, nonirrigation canals, rivers, and streams that are quiescent or slow moving.

Do not apply within 21 days of previous application.When treating moving bodies of water, applications must be made while travelingupstream to prevent concentration of 2,4-D downstream from the application.Coordination and approval of local and state authorities may be required, either by letter ofagreement or issuance of special permits for such use. 

Table 1. Amount of 2,4-D to Apply for a Target Subsurface Concentration

Surface Area Average Depth For typical

conditions - 2 ppm2,4-D ae/acre-foot

For difficultconditions* - 4ppm 2,4-D ae/acrefoot

1 acre

1 ft. 5.4 lbs 10.8 lbs2 ft. 10.8 lbs 21.6 lbs3 ft. 16.2 lbs 32.4 lbs4 ft. 21.6 lbs 43.2 lbs5 ft. 27.0 lbs 54.0 lbs

* Examples include spot treatment of pioneer colonies of Eurasian Water Milfoil andcertain difficult to control aquatic species. 
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Use-Specific ApplicationRestrictions

Water Use:

1. Water for irrigation or sprays:A. If treated water is intended to be used only for crops or non-crop areas that are labeledfor direct treatment with 2,4-D such as pastures, turf, or cereal grains, the treated water maybe used to irrigate and/or mix sprays for these sites at anytime after the 2,4-D aquaticapplication.B. Due to potential phytotoxicity and/or residue considerations, the following restrictions

are applicable:If treated water is intended to be used to irrigate or mix sprays for unlabeled crops, noncrop areas or other plants not labeled for direct treatment with 2,4-D, the water must not beused unless one of the following restrictions has been observed:i. A setback distance described in the Drinking Water Setback Table was used for theapplication, or,ii. A waiting period of 21 days from the time of application has elapsed, or,iii. An approved assay indicates that the 2,4-D concentration is 100 ppb (0.1 ppm) or less atthe water intake. See Table 3 for the waiting period after application but before taking theinitial sampling at water intake.2. Drinking water (potable water):A. Consult with appropriate state or local water authorities before applying this product to

public waters. State or local agencies may require permits.
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Use-Specific ApplicationRestrictions

The potable water use restrictions on this label are to ensure that consumption of water by

the public is allowed only when the concentration of 2,4-D in the water is less than theMCL (Maximum Contaminant Level) of 70 ppb. Applicators should consider the uniquecharacteristics of the treated waters to assure that 2,4-D concentrations in potable water donot exceed 70 ppb at the time of consumption.B. For submersed weed applications, the drinking water setback distances fromfunctioning potable water intakes are provided in Table 2. Drinking Water SetbackDistance (below).C. If no setback distance from the Drinking Water Setback Table (Table 2) is to be used forthe application, applicators or the authorizing organization must provide a drinking waternotification and an advisory to shut off all potable water intakes prior to a 2,4-Dapplication. Notification to the party responsible for a public water supply or to individualprivate water users must be done in a manner to assure that the party is aware of the wateruse restrictions when this product is applied to potable water. The following is an exampleof a notification via posting, but other methods of notification which convey the aboverestrictions may be used and may be required in some cases under state or local law or as a

condition of a permit.
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Use-Specific ApplicationRestrictions

Example:Posting notification should be located every 250 feet including the shoreline of the treatedarea and up to 250 feet of shoreline past the application site to include immediate public

access points. Posting should include the day and time of application. Posting may beremoved if analysis of a sample collected at the intake no sooner than stated in Table 3(below) shows that the concentration in the water is less than 70 ppb (100 ppb for irrigationor sprays), or after 21 days following application, whichever occurs first.Text of notification: Wait 21 days before diverting functioning surface water intakes from

the treated aquatic site to use as drinking water, irrigation, or sprays, unless water atfunctioning drinking water intakes is tested no sooner than (insert days from Table 3) and is

demonstrated by assay to contain not more than 70 ppb 2,4-D (100 ppb for irrigation or

sprays).Application Date: ______ Time: _____ .D. Following each application of this product, treated water must not be used for drinking

water unless one of the following restrictions has been observed:i. A setback distance described in the Drinking Water Setback Distance Table was used for

the application, or,ii. A waiting period of at least 21 days from the time of application has elapsed, or,
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Use-Specific ApplicationRestrictions

iii. An approved assay indicates that the 2,4-D concentration is 70 ppb (0.07 ppm) or less at

the water intake. Sampling for drinking water analysis should occur no sooner than statedin Table 3. Analysis of samples must be completed by a laboratory that is certified underthe Safe Drinking Water Act to perform drinking water analysis using a currently approvedversion of analytical Method Number 515, 555, other methods for 2,4-D as may be listed inTitle 40 CFR, Part 141.24, or Method Number 4015 (immunoassay of 2,4-D) from U.S.EPA Test Methods for Evaluating Solid Waste SW-846.E. Note: Existing potable water intakes that are no longer in use, such as those replaced bya connection to a municipal water system or a potable water well, are not considered to befunctioning potable water intakes.F. Drinking water setback distances do not apply to terrestrial applications of 2,4-Dadjacent to water bodies with potable water intakes.
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Use-Specific ApplicationRestrictions

3. Swimming (2,4-D butoxyethanol ester only):A. Do not swim in treated water for a minimum of 24 hours after application.B. Users must provide the following notification prior to performing a 2,4-D BEEapplication. Notification to the party responsible for the public swimming area or toindividual private users must be done in a manner to assure that the party is aware of thewater use swimming restrictions when this product is applied to water. The following is an

example of a notification via posting, but other methods of notification which convey theabove restrictions may be used and may be required in some cases under state or local lawor as a condition of a permit.Example:Posting notification should be located every 250 feet including the shoreline of the treatedarea and up to 250 feet of shoreline past the application site to include immediate publicaccess points.Text of Notification: Do not swim in treated water for a minimum of 24 hours afterapplication. Application Date: ______ Time: _____ .4. Except as stated above, there are no restrictions on using water from treated areas for

swimming, fishing, watering livestock or domestic purposes.”

Use-Specific ApplicationRestrictions

Table 2. Drinking Water Setback Distance 

for Submersed Weed Applications

Application Rate and Minimum Setback Distance (feet) From Functioning Potable Water

Intake
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1 ppm* 2 ppm* 3 ppm* 4 ppm*600 1200 1800 2400* ppm acid equivalent target water concentration

Table 3. Sampling for Drinking Water Analysis After 2,4-D Application for

Submersed Weed Applications

Minimum Days After Application Before Initial Water Sampling at the Functioning

Potable Water Intake

1 ppm* 2 ppm* 3 ppm* 4 ppm*5 10 10 14* ppm acid equivalent target water concentration”
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Use-Specific ApplicationRestrictions(Note: The maximumallowable application rate mustbe listed as pounds or gallonsof formulated product per acre,not just as pounds acidequivalent per acre.

“Asparagus”

Permitted forms of 2,4-D include acid, salts, and amines.“The preharvest interval (PHI) is 3 days.Limited to 2 applications per crop cycle. Maximum of 2.0 lb ae/acre per applicationMinimum of 30 days between applications.”“Blueberry, low bush”Permitted forms of 2,4-D include acid, salts, and amines.“Postemergence:Limited to one postemergence application per year. Maximum of 0.0375 lbs ae/gallons of spray solution per application.Postharvest:Limited to one postharvest application per year. Maximum of 1.0 lbs ae/gallon spray solution per application.For spot or directed wipe treatment only.Apply only in non-bearing years.”
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Use-Specific ApplicationRestrictions(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Blueberry, high bush”Permitted forms of 2,4-D include acid, salts, and amines.“The preharvest interval (PHI) is 30 days.Postemergence and postharvest: Limited to 2 applications per year.Maximum of 1.4 lbs ae/acre per application.”“Cereal Grains (wheat, barley, millet, oats, and rye)”Permitted forms of 2,4-D include acid, salts, amines, and esters.“The preharvest interval (PHI) is 14 days.Postemergence:Limited to one postemergence application per crop cycle.Maximum of 1.25 lbs ae/acre per application.Preharvest:Limited to one preharvest application per crop cycle.Maximum of 0.5 lbs ae/acre per application.Limited to 1.75 lbs ae/acre per crop cycle.”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Citrus (growing fruit)Permitted form of 2,4-D is isopropyl ester.“The preharvest interval (PHI) is 7 days.-To increase fruit size on growing Navel oranges, Valencia oranges, and grapefruit: 

Limited to one application per crop cycle. Maximum of 45 grams ae per acre (0.1 lbs ae/acre).-To reduce pre-harvest fruit drop on growing Navel oranges, Valencia oranges, and

grapefruit:

Limited to one application per crop cycle. Maximum rate of 200 ppm per application.-To prevent pre-harvest drop of mature fruit and leaves on lemons, Navel oranges, Valencia

oranges, and Tangelos:

Limited to one application per crop cycle. Maximum rate of 24 ppm per application.”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

Postharvest Citrus TreatmentPermitted form of 2,4-D is isopropyl ester.“Permitted application methods include dip or spray.Postharvest packing house application to lemons:

Limited to one application per crop.Maximum rate of 500 ppm per application.”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Corn, field and pop”Permitted forms of 2,4-D include acid, salts, amines, and esters.“Do not use treated crop as fodder for 7 days following application.The preharvest interval (PHI) is 7 days. Maximum of 3 lbs ae/acre per crop cycle. 

Preplant or preemergence:

Limited to one preplant or preemergence application per crop cycle.Maximum of 1.0 lb ae/acre per application. Postemergence:

Limited to one postemergence application per crop cycle.Maximum of 0.5 lb ae/acre per application.Preharvest:

Limited to one preharvest application per crop cycle.Maximum of 1.5 lbs ae/acre per application.” 
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Corn, sweet”Permitted forms of 2,4-D include acid, salts, amines, and esters.“Do not use treated crop as fodder for 7 days following application.The preharvest interval (PHI) is 45 days.Minimum of 21 days between applications.Maximum of 1.5 lbs ae/acre per crop cycle.Preplant or preemergence:

Limited to one preplant or preemergence application per crop cycle.Maximim of 1.0 lb ae/acre per application. Postemergence:

Limited to one postemergence application per crop cycle.Maximum of to 0.5 lb ae/acre per application.”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Cranberries”Permitted forms of 2,4-D include acid, salts, amines, and esters.“The preharvest interval (PHI) is 30 days.Dormant Season: 

Limited to one application per crop cycle.Maximum of 4.0 lbs ae/acre per dormant seasonPostemergence: 

Limited to 2 applications per crop cycle.Maximum of 1.2 lbs ae/acre per postemergence application.”“Filberts”Permitted forms of 2,4-D include acid, salts, and amines.“The preharvest interval (PHI) is 45 days.Minimum of 30 days between applications.Limited to 4 applications per year.Maximum of 1.0 lbs ae per 100 gallons of spray solution per application.

“Fallowland (crop stubble on idle land, or postharvest to crops, or between crops)”

Permitted forms of 2,4-D include acid, salts, amines, and esters.“Plant only labeled crops within 29 days following application.Limited to 2 applications per year.Maximum of 2.0 lbs ae/acre per application. Minimum of 30 days between applications.”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Forestry (forest site preparation, forest roadsides, brush control, established conifer

release, Chrismas trees, reforestation areas)”Permitted forms of 2,4-D include acid, salts, amines, and esters.Broadcast application: Limited to 1 broadcast application per year.Maximum of 4.0 lbs ae/acre per broadcast application.Basal spray, Cut Surface - Stumps, and Frill:Limit of one basal spray or cut surface application per year.Maximum of 8.0 lbs ae per 100 gallons of spray solution.Injection:Limit to one injection application per year.Maximum of 2 ml of 4.0 lbs ae formulation per injection site.”“Grapes”Permitted forms of 2,4-D include acid, salts, and amines.“For use only in California.The preharvest interval (PHI) is 100 days.Limited to 1 application per crop cycle.Maximum of 1.36 lbs ae/acre per application.”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Grasses (pastures and rangeland not in agricultural production)”

Permitted forms of 2.4-D include acid, salts, amines, and esters.“The preharvest interval (PHI) is 7 days (cut forage for hay).Postemergence: 

Limited to 2 applications per year.Maximum of 2.0 lbs ae/acre per application. Minimum of 30 days between applications.If grass is to be cut for hay, Agricultural Use Requirements for the Worker ProtectionStandard are applicable.For program lands, such as Conservation Reserve Program, consult program rules todetermine whether grass or hay may be used. The more restrictive requirements of theprogram rules or this label must be followed.”“Hops”Permitted forms of 2,4-D include acid and amines.“The preharvest interval (PHI) is 28 days.Postemergence: Limited to 3 applications per crop cycle.Maximum of 0.5 lb ae/acre per application. Maximum of 1.5 lbs ae/acre per crop cycle.Minimum of 30 days between applications.”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Non-Cropland (fencerows, hedgerows, roadsides, ditches, rights-of-way, utility

power lines, railroads, airports, and industrial sites)”Permitted forms of 2,4-D include acid, salts, amines, and esters.“Postemergence (annual and perennial weeds): 

Limited to 2 applications per year.Maximum of 2.0 lbs ae/acre per application.Minimum of 30 days between applications.Postemergence (woody plants): 

Limited to 1 application per year.Maximum of 4.0 lbs ae/acre per year.Applications to non-cropland areas are not applicable to treatment of commercial timber orother plants being grown for sale or other commercial use, or for commercial seedproduction, or for research purposes.” 
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Pasture and Rangeland (established grass pastures, rangeland, and perennial

grasslands not in agricultural production)”Permitted forms of 2,4-D include acid, salt, amines, and esters.“Do not cut forage for hay within 7 days of application.

Postemergence: 

For susceptible annual and biennial broadleaf weeds: Use 1.0 lbs ae/acre per application.

For moderately susceptible biennial and perennial broadleaf weeds: Use 1.0 to 2.0 lbsae/acre per application.For difficult to control weeds and woody plants: Use 2.0 lbs ae/acre per application.Spot treatment: Use 2.0 lbs ae/acre.Maximum of two applications per year.Maximum of 4.0 lbs ae/acre per year. Minimum of 30 days between applications.If grass is to be cut for hay, Agricultural Use Requirements for the Worker ProtectionStandard are applicable.”“Pistachios”Permitted forms of 2,4-D include acid, salts, and amines.“Do not cut orchard floor forage for hay within 7 days of application.The preharvest interval (PHI) is 60 days.Postemergence: 

Limited to 2 applications per year.Maximum of 2.0 lbs ae/acre per application. Minimum of 30 days between applications.”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Pome Fruits”Permitted forms of 2,4-D include acid, salts, and amines. “The preharvest interval (PHI) is 14 days.Do not cut orchard floor forage for hay within 7 days of application.Postemergence: 

Limited to 2 applications per crop cycle.Maximum of 2.0 lbs ae/acre per application. Minimum of 75 days between applications.”“Potatoes”Permitted forms of 2,4-D include acid, salts, amines, and esters.“Only for use on potatoes intended for fresh market.The preharvest interval (PHI) is 45 days.Postemergence: Limited to 2 applications per crop cycle.Maximum of 0.07 lb ae/acre per application.Minimum of 10 days between applications.”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Rice”Permitted forms of 2,4-D include acid, salts, and amines.“The preharvest interval (PHI) is 60 days.Maximum of 1.5 lbs ae/acre per crop cycle.”Preplant:

Limited to one preplant application per crop cycle.Maximum of 1.0 lbs ae/acre per preplant application..Postemergence: 

Limited to one postemergence application per crop cycle.Maximum of 1.5 lbs ae/acre per postemergence application.“Rice, wild”Permitted forms of 2,4-D include acid, salts, and amines.“For use in Minnesota only.The preharvest interval (PHI) is 60 days.Postemergence: Limited to 1 application per crop cycle .Maximum of 0.25 lb ae/acre per application.” 
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Sorghum”Permitted forms of 2,4-D include acid, salts, amines, and esters.“The preharvest interval (PHI) is 30 days.Do not permit meat or dairy animals to consume treated crop as fodder or forage for 30days following application.Postemergence (acid, salts, and amines): 

Limited to 1 application per crop cycle.Maximum of 1.0 lb ae/acre per application.Postemergence (esters): 

Limited to 1 application per crop cycle.Maximum of 0.5 lb ae/acre per application.”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Soybeans”

Permitted forms of 2,4-D include acid, salts, amines, and esters.“The maximum rate per crop cycle is 1.0 lb ae/acre.Preplant: 

Limited to 2 preplant applications per crop cycle.Maximum of 0.5 lb ae/acre per preplant application.> Esters: Apply not less than 7 days prior to planting soybeans.>Amines, acid, salts: Apply not less than 15 days prior to planting soybeans.” or“Preplant: 

Limited to 1 application per crop cycle.Maximum of 1.0 ae/acre per preplant application. >Esters: Apply not less than 15 days prior to planting soybeans.>Amines, acid, salts: Apply not less than 30 days prior to planting soybeans.”“Stone Fruits”Permitted forms of 2,4-D include acid, salts, and amines.“The preharvest interval (PHI) is 40 days.Do not cut orchard floor forage for hay within 7 days of application.Postemergence: 

Limited to 2 applications per crop cycle.Maximum of 2.0 lb ae/acre per application.Minimum of 75 days between applications.”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Strawberry”Permitted forms of 2,4-D include acid, salts, and amines.“Do not apply in California or Florida.Dormant or after last picking: 

Limited to 1 application per crop cycle.Maximum of 1.5 lbs ae/acre per application.”“Sugarcane”Permitted forms of 2,4-D include acid, salts, and amines.“Do not harvest cane prior to crop maturity.Do not apply more than 4 lbs ae/acre per crop cycle.Preemergence:

Limited to one application per crop cycle.Maximum of 2.0 lbs ae/acre per application.Postemergence: 

Limited to one application per crop cycle. Maximum of 2.0 lbs ae/acre per application..”
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Other Application Restrictions(Risk Mitigation)(Note: The maximumallowable application rate andmaximum allowable rate peryear must be listed as poundsor gallons of formulatedproduct per acre, not just aspounds acid equivalent peracre.)

“Tree Nuts”Permitted forms of 2,4-D include acid, salts, and amines.“The preharvest interval (PHI) is 60 days.Do not cut orchard floor forage for harvest within 7 days of application.

Postemergence: 

Limited to 2 applications per crop cycleMaximum of 2.0 lbs ae/acre per application.Minimum of 30 days between applications.” “Turf, ornamental (golf courses, cemetaries, parks, sports fields, turfgrass, lawns and

other grass areas)”Permitted forms of 2,4-D include acid, salts, amines, and esters.“Postemergence: 

Limited to 2 applications per year.Maximum of 1.5 lbs ae/acre per application. The maximum seasonal rate is 3.0 lbs ae/acre, excluding spot treatments.”“Turf, grown for seed or sod”Permitted forms of 2,4-d include acid, salts, amines, and esters.“Limited to 2 applications per year.Maximum of 2.0 lbs ae/acre per application.Minimum of 21 days between applications.”
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Spray Drift “SPRAY DRIFT MANAGEMENT”

 “A variety of factors including weather conditions (e.g., wind direction, wind speed,temperature, relative humidity) and method of application (e.g., ground, aerial, airblast,

chemigation) can influence pesticide drift. The applicator must evaluate all factors andmake appropriate adjustments when applying this product.” Droplet Size “When applying sprays that contain 2,4-D as the sole active ingredient, or when applyingsprays that contain 2,4-D mixed with active ingredients that require a Coarse or coarserspray, apply only as a Coarse or coarser spray (ASAE standard 572) or a volume meandiameter of 385 microns or greater for spinning atomizer nozzles.” “When applying sprays that contain 2,4-D mixed with other active ingredients that requirea Medium or more fine spray, apply only as a Medium or coarser spray (ASAE standard572) or a volume mean diameter of 300 microns or greater for spinning atomizer nozzles.”Wind Speed “Do not apply at wind speeds greater than 15 mph. Only apply this product if the winddirection favors on-target deposition and there are not sensitive areas (including, but notlimited to, residential areas, bodies of water, known habitat for nontarget species, nontargetcrops) within 250 feet downwind. If applying a Medium spray, leave one swath unsprayedat the downwind edge of the treated field.” 
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Temperature Inversions “If applying at wind speeds less than 3 mph, the applicator must determine if: a)conditions of temperature inversion exist, or b) stable atmospheric conditions exist at orbelow nozzle height. Do not make applications into areas of temperature inversions orstable atmospheric conditions.”Susceptible Plants “Do not apply under circumstances where spray drift may occur to food, forage, or otherplantings that might be damaged or crops thereof rendered unfit for sale, use orconsumption. Susceptible crops include, but are not limited to, cotton, okra, flowers,grapes (in growing stage), fruit trees (foliage), soybeans (vegetative stage), ornamentals,sunflowers, tomatoes, beans, and other vegetables, or tobacco. Small amounts of spraydrift that might not be visible may injure susceptible broadleaf plants.” Other State and Local Requirements “Applicators must follow all state and local pesticide drift requirements regardingapplication of 2,4-D herbicides. Where states have more stringent regulations, they must beobserved.”Equipment “All aerial and ground application equipment must be properly maintained and calibratedusing appropriate carriers or surrogates.”Additional requirements for aerial applications: “The boom length must not exceed 75% of the wingspan or 90% of the rotor bladediameter.”
Page 151 of 304

 “Release spray at the lowest height consistent with efficacy and flight safety. Do notrelease spray at a height greater than 10 feet above the crop canopy unless a greater heightis required for aircraft safety. This requirement does not apply to forestry or rights-of-wayapplications.” “When applications are made with a crosswind, the swath will be displaced downwind. The applicator must compensate for this by adjusting the path of the aircraft upwind.”Additional requirements for ground boom application: “Do not apply with a nozzle height greater than 4 feet above the crop canopy.”Additional requirements for liquid products applied as a spray and containing an esterform of 2,4-D (e.g. 2,4-D butoxyethyl ester, 2,4-D ethylhexyl ester, 2,4-D isopropyl ester): “2,4-D esters may volatilize during conditions of low humidity and high temperatures. Do not apply during conditions of low humidity and high temperatures.”

End Use Products Intended for Residential Use

Application Restrictions “Do not apply this product in a way that will contact any person or pet, either directly or

through drift. Keep people and pets out of the area during application.”

Entry Restrictions for liquids,water-dispersible granules, andwettable powders formulatedin water-soluble packages

“Do not allow people or pets to enter the treated area until sprays have dried.” 
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Entry Restrictions for granularformulations

“Do not allow people or pets to enter the treated area until dusts have settled.” 

Environmental HazardStatement for Residential Uselabels

“This pesticide is toxic to fish and aquatic invertebrates. Do not apply directly to water, to

areas where surface water is present, or to intertidal areas below the mean high water markexcept as noted on appropriate labels. Drift and runoff may be hazardous to aquaticorganisms in water adjacent to treated areas. Do not contaminate water when disposing ofequipment wash waters or rinsate.2

This chemical has properties and characteristics associated with chemicals detected ingroundwater. The use of this chemical in areas where soils are permeable, particularlywhere the water table is shallow, may result in groundwater contamination. Applicationaround a cistern or well may result in contamination of drinking water or groundwater.” 

1 PPE that is established on the basis of Acute Toxicity of the end-use product must be compared to the active ingredient PPE in th

protective PPE must be placed in the product labeling. For guidance on which PPE is considered more protective, see PR Notice 

2 May be deleted for ready-to-use products. 
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VI. Appendicies
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Appendix A. Table of 2,4-D Use Patterns Eligible for Reregistration (Case 0073)
Page 155 of 304

Appendix A. Use Patterns Subject to Reregistration for 2,4-D (Case 0073)

Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Aquaticweed control- Ditchbankapplication

Wettable powder,Emulsifiableconcentrate,Solubleconcentrate -liquid,Solubleconcentrate -solid,Granular

2.0 Lbs ae/acre 2 per season 4.0 lbs

ae/acre

30 NA NA 

Aquaticweed control- floatingandemergentweeds

Wettable powder,Emulsifiableconcentrate,Solubleconcentrate -liquid,Solubleconcentrate -solid,Granular

4.0 Lbs

ae/surfaceacre

2 per season 8.0 lbs

ae/surfaceacre

21 NA NA 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 156 of 304

Aquaticweed control- submersedweeds

Wettable powder,Emulsifiableconcentrate,Solubleconcentrate -liquid,Solubleconcentrate -solid,Granular

10.8 Lbs ae per

acre-foot

2 per season 21.6 lbs ae

per acre-footper season

21 24 hour

swimmingrestriction for2,4-D BEE form

NA 

Asparagus Wettable powder,

Emulsifiableconcentrate,solubleconcentrate -liquid, solubleconcentrate - solid

2.0 Lbs ae/acre 2 per crop

cycle

4.0 lbsae/acre

30 2,4-D acid and

amines -48hours;2,4-D salt andesters - 12 hours 

NA 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 157 of 304

Blueberry,low bush

Wettable powder,Emulsifiableconcentrate,solubleconcentrate -liquid, solubleconcentrate - solid

Postemergence:0.0375 Postharvest:1.0

lbs ae pergallon spraysolution perapplication

Postemergence: 1Postharvest:1

0.0375 lbs aeper gallonspraysolution

NA 2,4-D acid and

amines -48hours;2,4-D salt andesters - 12 hours 

NA 

Blueberry,high bush

Wettable powder,Emulsifiableconcentrate,solubleconcentrate -liquid, solubleconcentrate - solid

1.4 Lbs ae/acre 2 per year 2.8 lbs

ae/acre

NS 2,4-D acid and

amines -48hours;2,4-D salt andesters - 12 hours 

PHI - 30 days 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 158 of 304

Citrus,growing fruit

Emulsifiableconcentrate

Toincreasefruit sizeongrowingNaveloranges,Valenciaoranges,andgrapefruit:0.1To reducepreharvestfruit dropongrowingNaveloranges,Valenciaoranges,andgrapefruit: 200

To increasefruit size ongrowingNaveloranges,Valenciaoranges, andgrapefruit:lbs ae/acreTo reducepre-harvestfruit drop ongrowingNaveloranges,Valenciaoranges, andgrapefruit:ppm

1 per cropcycle

same asmax. singleapp. rate

NA 12 hours PHI - 7 days 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 159 of 304

Topreventpreharvestdrop ofmaturefruit andleaves onlemons,Naveloranges,Valenciaoranges,andTangelos:24

To preventpre-harvestdrop ofmature fruitand leaveson lemons,Naveloranges,Valenciaoranges, andTangelos:ppm

1 same as

max. singleapp. rate

Citrus,postharvesttreatement

Emulsifiableconcentrate

500 ppm 1 500 ppm NA NA NA 

Corn, fieldand pop

Wettable powder,Emulsifiableconcentrate,Granular, Solubleconcentrate -liquid, Solubleconcentrate - solid

Preplantorpreemergence: 1.0Postemergence: 0.5Preharvest: 1.5

Lbs ae/acre Preplant or

preemergence: 1Postemergence: 1Preharvest: 1

3.0 lbsae/acre

NA 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

PHI - 7 daysPGI - 7 days
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 160 of 304

Corn, sweet Wettable powder,

Emulsifiableconcentrate,Granular, Solubleconcentrate -liquid, Solubleconcentrate - solid

Preplantorpreemergence: 1.0 Postemergence: 0.5

Lbs ae/acre Preplant or

preemergence: 1 Postemergence: 1

1.5 lbsae/acre percrop cycle

21 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

PHI - 45 daysPGI - 7 days

Cranberries Wettable powder,

Emulsifiableconcentrate,Granular, Solubleconcentrate -liquid, Solubleconcentrate - solid

Dormantseason:4.0Postemergence: 1.2

Dormantseason: lbsae/acre perdormantseasonPostemergence: lbsae/acre perpostemergenceapplication 

Dormantseason: 1Postemergence: 2

Dormantseason: 4 lbsae/acre perdormantseasonPostemergence: 2.4 lbsae/acre perpostemergenceapplication 

NS 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

PHI - 30 days 

Filberts Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

1.0 lbs ae per

100 gallonsof spraysolution 

4 4.0 lbs ae per

100 gallonsof spraysolution peryear

30 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

PHI - 45 days 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 161 of 304

Fallowland(crop stubbleon idle land,orpostharvestto crops, orbetweencrops)

Wettable powder,Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

2.0 Lbs ae/acre 2 per year 4.0 lbs

ae/acre peryear

30 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

NS 

Forestry(forest sitepreparation,forestroadsides,brushcontrol,establishedconiferrelease,Christmastrees,reforestationareas)

Wettable powder,Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

Broadcast:4.0Basalspray, cutsurface -stumps,frill: 8.0Injection:2

Broadcast:lbs ae/acreBasal spray,cut surface -stumps, frill:lbs ae per100 gallonsof spraysolutionInjection: mlof 4.0 lbs aeformulationper injectionsite

1 per year Broadcast:

4.0 lbsae/acre peryearBasal spray,cut surface -stumps, frill:lbs ae per100 gallonsof spraysolutionInjection: mlof 4.0 lbs aeformulationper injectionsite 

NA 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

NA 

Grapes Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

1.36 lbs ae/acre 1 per crop

cycle

1.36 lbsae/acre peryear

NA 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

PHI - 100 days 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 162 of 304

Grasses(pastures andrangelandnot inagriculturalproduction)

Wettable powder,Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

2.0 Lbs ae/acre 2 per year 4.0 lbs

ae/acre peryear

30 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

PHI - 7 days 

Hops Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

0.5 Lbs ae/acre 3 per crop

cycle

1.5 lbsae/acre percrop cycle

NS 2,4-D acid and

amines - 48hours

PHI - 28 days 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 163 of 304

NonCropland(fenecrows,hedgerows,roadsides,ditches,rights-ofway, utilitypower lines,railroads,airports, andindustrialsites)

Wettable powder,Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate -solid, Granular

Postemergence(annualandperennialplants): 2Postemergence(woodyplants): 4

lbs ae/acre Postemergen

ce (annualandperennialplants): 2Postemergence (woodyplants): 1

4.0 lbsae/acre

Postemergence(annualandperennialplants): 30daysPostemergence(woodyplants):NA

2,4-D acid andamines - 48hours;2,4-D salt andesters - 12 hours

NA 

NutOrchards 

Wettable powder,Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

2.0 Lbs ae/acre 2 per year 4.0 lbs

ae/acre peryear

30 2,4-D acid and

amines - 48hours;2,4-D salt - 12hours

NS 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 164 of 304

Pasture andRangeland(establishedgrasspastures,rangeland,andperennialgrasslandsnot inagriculturalproduction)

Wettable powder,Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

Susceptible annualandbiennialbroadleafweeds: 1.0Moderatelysusceptible biennialandperennialbroadleafweeds: 1.0to 2.0Difficultto controlweeds andwoodyplants: 2.0Spottreatment:2.0

Lbs ae/acre 2 per year 4.0 lbs

ae/acre

30 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

Pome fruits Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

2.0 Lbs ae/acre 2 per crop

cycle

4.0 lbsae/acre

75 2,4-D acid and

amines - 48hours;2,4-D salt - 12hours

PHI - 14 days 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 165 of 304

Potatoes Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

0.07 Lbs ae/acre 2 per crop

cycle

0.14 per cropcycle

10 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

PHI - 45 days 

Rice Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

Preplant:1.0Postemergence:1.5

Lbs ae/acre Preplant: 1

per cropcyclePostemergence: 1 percrop cycle

1.5 lbsae/acre percrop cycle

NA 2,4-D acid and

amines - 48hours;2,4-D salt - 12hours

PHI - 60 days 

Rice, wild Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

0.25 Lbs ae/acre 1 per crop

cycle

0.25 lbsae/acre percrop cycle

NA 2,4-D acid and

amines - 48hours;2,4-D salt - 12hours

PHI - 60 days 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 166 of 304

Sorghum Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

Postemergence(acid,salts, andamines):1.0Postemergence(esters):0.5

Lbs ae/acre 1 per crop

cycle

Postemergence (acid,salts, andamines): 1.0lbs ae/acreper cropcyclePostemergence (esters):0.5 lbsae/acre percrop cycle

NA 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

PHI - 30 days 

Soybean Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

1.0 Lbs ae/acre 1 app. of 1.0

lbs ae/acreper cropcycleOR2 apps. Of0.5 lbsae/acre percrop cycle

1.0 lbsae/acre percrop cycle 

NS 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

- 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 167 of 304

Stone fruits Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

2.0 Lbs ae/acre 2 4.0 lbs

ae/acre percrop cycle

75 2,4-D acid and

amines - 48hours;2,4-D salt - 12hours

PHI - 40 days 

Strawberry Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

1.5 Lbs ae/acre 1 1.5 lbs

ae/acre percop cycle

NA 2,4-D acid and

amines - 48hours;2,4-D salt - 12hours

- 

Sugarcane Wettable powder,

Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate - solid

Preemergence: 2.0Postemergence: 2.0

Lbs ae/acre Preemergenc

e: 1Postemergence: 1

4 lbs ae/acreper cropcycle

NS 2,4-D acid and

amines - 48hours;2,4-D salt - 12hours

- 
Use Site Formulation Max.

SingleApp.Rate 

Unit Max. #

App. PerCropCycle/Year

Max. App.Rate PerCropCycle/Year 

Min.RetreatmentInterval(days)

ReentryInterval (REI)

PreharvestInterval (PHI)PregrazingInterval (PGI)PreslaughteringInterval (PSI)

Page 168 of 304

Turf,ornamental(golfcourses,cemetaries,parks, sportsfields,turfgrass,lawns, andother grassareas)

Wettable powder,Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate -solid, Granular

1.5 Lbs ae/acre 2 3.0 lbs

ae/acre peryear,excludingspottreatments

NS NS - 

Turf, grownfor seed orsod

Wettable powder,Emulsifiableconcentrate, Solubleconcentrate -liquid, Solubleconcentrate -solid, Granular

2.0 Lbs ae/acre 2 4.0 lbs

ae/acre percrop cycle

21 2,4-D acid and

amines - 48hours;2,4-D salt andesters - 12 hours

- 
Page 169 of 304

Appendix B. Data Supporting Guideline Requirements for the Reregistration of 2,4-D
Page 170 of 304

Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)PRODUCT CHEMISTRYNewGuidelineNumber

OldGuidelineNumber

830.1550 61-1 Product Identity and Composition All

41219701, 41223801, 41926201, 4343981801, 40808301, 41219601, 4141220101, 41973501, 41055801, 4141973501, 41067001, 41203301, 4141055810, 41964401, 41055815, 4144807001, 41055818, 41055819, 4141961301, 41055806, 41055807, 4142188601, 42786501, 40443301, 41

830.1600 61-2A Description of materials used to produce the product All

41223801, 41637501, 41790601, 4443516401, 40808301, 41246701, 4141055804, 41496701, 41055801, 4141067001, 41599401, 42537501, 4441055815, 41055818, 41055812, 4441055806, 44982101, 41015001, 4240443301, 41224201

830.1620 61-2B Description of production process

41223801, 41790601, 44149301, 4440808301, 41246701, 41796201, 4141973501, 41067001, 41599401, 4144184201, 41055809, 41055815, 4441055818, 44228301, 41055812, 4441055806, 44982101, 41015001, 4240443301, 41224201
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 171 of 304

830.1670 61-2B Formation of Impurities All

41223801, 41790601, 44149301, 4440808301, 41246701, 41496701, 441067001, 41599401, 41789901, 4142537501, 44184201, 41055809, 4141055815, 41978001, 42798301, 441055818, 42798201, 44228301, 4144584501, 44963803, 41055806, 4141015001, 42188601, 42786501, 40

830.1700 62-1 Preliminary Analysis All

41219701, 41926201, 41790602, 4444543503, 44932701, 43516401, 4340808301, 41724201, 41724202, 4141796202, 41219601, 41796202, 4141496701, 41973501, 43777501, 4441220101, 41496701, 41973501, 4341067001, 41203301, 41735701, 4141964401, 43314701, 41055816, 4141055813, 44963801, 41349002, 4141055807, 45014801, 41015002, 4241206901

830.1750 62-2 Certification of limits All

41219701, 41223801, 41926201, 4343981801, 40808301, 41219601, 4141220101, 41496701, 41973501, 4141220101, 41496701, 41973501, 441599401, 41123601, 41055809, 4141055815, 41055816, 41978001, 4441055819, 41055812, 41055813, 4141055806, 41055807, 41968301, 4140443301, 41206901
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 172 of 304

830.1800 62-3 Analytical Method All

41219701, 41223801, 41637501, 4144543503, 43516401, 43516402, 4341219601, 41796202, 41055802, 4141055802, 41220101, 41496701, 4141599401, 41789902, 41123601, 4141055819, 41055813, 449638034, 444982102, 41015002, 42188601, 4241206901

830.6302 63-2 Color All

41223801, 44543504, 43516403, 4341055803, 41067001, 41123601, 4241055817, 41055820, 41055814, 4441015003, 40443301, 41224201

830.6303 63-3 Physical State All

41223801, 44543504, 43516403, 441055803, 41067001, 41123601, 4241055817, 41055820, 41055814, 4441015003, 40443301, 41224201

830.6304 63-4 Odor All

41223801, 44543504, 43516403, 441055803, 41067001, 41123601, 4241055817, 41055820, 41055814, 4441015003, 40443301, 41224201

830.6313 63-13 Stability to normal and elevated temperatures, metals, and metal ions All

41223801, 41745301, 42023601, 4441855701, 42023601, 42795401, 4340808301, 41055803, 41855701, 4241055803, 42795401, 41973502, 4142857209, 41978002, 42487901, 4141015003, 42116702, 42786501, 40

830.6314 Oxidation/Reduction: Chemical Incompatibility All 42023601, 43516403, 43516404, 40

41067001, 41055811, 41055817, 4141968303, 44963802, 41055808, 40
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 173 of 304

830.6315 Flammability All 41055811, 41055817, 41055820, 41

41015003, 40443301, 41224201

830.6316 Explodability All

41745302, 43516403, 43516404, 4041067001, 42537501, 41055811, 4141055814, 41055808, 41015003, 40

830.6317 Storage stability All

41745301, 41926203, 43516403, 4343260501, 41067001, 41123601, 4245642701, 41055817, 43874601, 4141055808, 41015003, 42786501, 40

830.6319 Miscibility All 40443301, 41224201830.6320 Corrosion characteristics

42023601, 43516403, 43516404, 4041973501, 41067001, 41123601, 4245642701, 41055817, 41055820, 4141015003, 40443301, 41224201

830.7000 63-12 pH All

41926202, 44543504, 43516403, 4341123601, 42857208, 41055811, 4141015003, 40443301, 41224201

830.7050 None UV/Visable Absorption All 44543504, Datagap

830.7100 Viscosity All 41055811, 41055817, 41055820, 41

41015003, 40443301, 41224201

830.7200 63-5 Melting Point All

41223801, 44543504, 41055803, 4143516403, 43516404, 40808301, 4142537501, 42857209, 42829901, 42

830.7220 63-6 Boiling Point All 43325001, 42830901, 43325001, 44

44963802, 42831101, 41015003, 40
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 174 of 304

830.7300 63-7 Density All

41223801, 44543504, 43516403, 4341055803, 41973501, 41067001, 4142857204, 41055811, 41055817, 4144963802, 41055808, 41015003, 40

830.7370 63-10 Dissociation constants in water All

41223801, 41308901, 44543504, 4141972501, 44543504, 43516403, 4341055803, 41067001, 41332009, 41

830.7550 63-11 Partition coefficient, shake flask method All

41332004, 44543504, 41332004, 4340808301, 41055803, 41067001, 4241647001, 44963802, 41055808, 4441015003, 42116702, 40443301, 41

830.7840 63-8 Solubility All

41223801, 42023601, 41332002, 4441055803, 45692501, 43516403, 4345692501, 41055803, 41067001, 4142537501, 42857205, 43358801, 4141978001, 43358802, 41669501, 4244963802, 41055808, 41968302, 41

42786501, 43302001, 40443301, 41

830.7950 63-9 Vapor Pressure All

41223801, 44543504, 41055803, 4143516403, 43516404, 40808301, 4142537501, 42857206, 42021001, 4144963802, 41055808, 44963802, 4140443301, 41224201

ECOLOGICAL FATE AND EFFECTS835.2120 161-1 Hydrolysis A, B 410073-01, 413537-01, 414831-01, 41

427354-01, 427705-02, 427705-01

835.2240 161-2 Photodegradation in Water A, B 411253-06, 414831-02, 427497-02835.2410 161-3 Photodegradation on Soil A, B 411253-05, 427497-02
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 175 of 304

835.2370 161-4 Photodegradation in Air A, B 414831-03

835.4100 162-1 Aerobic Soil Metabolism A, B 431675-01, 437991-01, 431496-01, 43

437991-02, 438215-01

835.4200 162-2 Anaerobic Soil Metabolism A, B 433560-01, 434159-01, 835.4400 162-3 Anaerobic Aquatic Metabolism A, B 415579-01, 433560-01, 425747-01, 4

438829-01, 439083-01, 437991-05, 43

835.4300 162-4 Aerobic Aquatic Metabolism A, B

420453-01, 429792-01, 441886-01, 436910-01, 436859-02, 444394-01, 437991-07 

835.1230 163-1 Leaching-Adsorption/Desorption A, B 420253-02, 441179-01, 441585-01, 

835.1410 163-2 Laboratory Volatility A, B 417180-01, 420596-01, Datagap

835.8100 163-3 Field Volatility A, B835.6100 164-1 Terrestrial Field Dissipation A, B

435146-01, 435334-01, 435428-01, 436437624-04, 437624-03, 437624-01, 438438491-02, 438640-01, 439147-01, 438446031-01, 434704-01, 436697-02, 435435928-02, 436121-01, 436768-03, 437438107-01, 438317-03, 438343-01, 438438727-02, 438727-01, 438724-01, 446

835.6200 164-2 Aquatic Field Dissipation A, B 445250-01, 439083-02, 439547-01, 434

439083-02, 439547-01, Datagap

835.6300 164-3 Forestry Dissipation A, B 439083-03, 439271-01, 439547-02, Da

840.1100 201-1 Droplet Size Spectrum A, B Datagap

840.1200 202-1 Drift Field Evaluation A, B Datagap

850.2100 71-1A Avian Acute Oral Toxicity A, B 415462-02, 419751-01, 415462-01, 233

414541-01, 411583-03, 72472, 226397
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 176 of 304

850.2200

71-2A71-2B Avian Dietary Toxicity A, B

415861-01, 415462-02, 419751-02, 419233351, 417495-02, 00138870, 001388414484-01, 414290-07, 411583-05, 450439349-01, 439352-01

850.2300

71-4A71-4B Avian Reproduction A, B 453364-01

850.1075 72-1 Fish Toxicity Bluegill A, B

411583-01, 53986, 419751-05, 419751411583-11, 419751-04, 234027, 41975413538-04, 413538-01, 00050674, 00045069, 439331-01, 439332-01, 439307439103-01, Datagap

850.1010 72-2A Invertebrate Toxicity A, B 411583-01, 419751-06, 232630, 41353

850.1075 72-3A Estuarine/Marine Toxicity - Fish A, B

429797-01, 417373-06, 420183-02, 419419734-01, 411583-11, 418252-08, 232414290-06, 411583-10, 418352-04, 418418352-06, 418352-03

850.1025 72-3B Estuarine/Marine Toxicity - Mollusk A, B 429797-01, 420183-02, 411583-11, 419

414290-06, 411583-10, 418352-04, 418

850.1035 72-3C Estuarine/Marine Toxicity - Shrimp A, B 417373-06, 419751-07, 411583-11, 419

414290-05, 418352-06, 418352-03, Da

850.1045 72-3 Estuarine/Marine Toxicity - Penaid A, B Datagap

850.1300 72-4A Fish Early Life Stage - Daphnid A, B 417373-04, 420183-04, 417677-01

850.1350 72-4B Estuarine/Marine Invertebrate Life Cycle A, B 418352-11, 420183-03, 418352-10, 413850.1400 72-4C Freshwater Fish- Acute Toxicity A, B850.1500 72-5 Life Cycle Fish A, B 413457-01, 417373–05850.4100 122-1A Terrestrial Plant Toxicity, Seedling Emergence A, B
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 177 of 304

850.5400 122-2 Aquatic Plant Growth A, B850.4225 123-1A Seedling Germination and Seedling Emergence A, B 424168-02, 426091-1, 442756-01, 430

03, 431970-02, 431970-01, 424492-01, 

850.4250 123-1B Vegetative Vigor A, B 424168-01, 426091-02, 423439-02, 437

439821-01, Datagap

850.4400 123-2 Aquatic Plant Growth A, B

442951-01, 427122-04, 427122-05, 427427122-03, 415059-04, 414200-02, 415415059-02, 417321-02, 434886-02, 417434886-04, 434886-01, 420684-04, 417420684-03, 417352-03, 417352-06, 417417352-02

850.3020 141-1 Honey Bee Acute Contact A, B 445173-04, 445173-01TOXICOLOGY870.1100 81-1 Acute Oral Toxicity-Rat A, B 00101605, 41920901, 00157512, 00252

40629801, 41209001

870.1200 81-2 Acute Dermal Toxicity-Rabbit/Rat A, B 00101596, 41920911, 00157513, 00252

40629802, 41209002

870.1300 81-3 Acute Inhalation Toxicity-Rat A, B 00161660, 41986601, 00157514, 40085

40629803, 42605202

870.2400 81-4 Primary Eye Irritation-Rabbit A, B 41125302, 41920902, 00157515, 00252

40629804, 44725303

870.2500 81-5 Primary Skin Irritation A, B 42232701, 41920903, 00157516, 00252

40629805, 41413505

870.2600 81-6 Dermal Sensitization A, B 00161659, 41920904, 41642805, 41233

40629806, 41209006

870.3100 82-1A Subchronic Oral Toxicity: 90-Day Study Rodent A, B 41991501, 41928101, 41994001, 4189

43515901, 42021402
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 178 of 304

870.3150 82-1B Subchronic Oral Toxicity: 90-Day Study Non-rodent A, B 41737301, 42780001, 42780003, 4351870.3200 82-2 21-Day Dermal - Rabbit/Rat A, B 41735304, 41735301, 41407901, 4192

41735302, 41735305, 41407903, 4140

870.3465 82-4 90-Day Inhalation-Rat A, B Datagap

870.4100 83-1B Chronic Feeding Toxicity A, B 43612001, 430490001

870.3700 83-3A Developmental Toxicity - Rat A, B

00130407, 00130408, 41527101, 41527

41735201, 42304601, 42304602, 4352341527106, 41527102; 41527105

870.3700 83-3B Developmental Toxicity - Rabbit A, B 41747601, 42158703, 42158706, 4205

42304603, 42304604, 42158702; 4215

870.3800 83-4 2-Generation Reproduction - Rat A, B 00150557, 00163996, Repeat Study R870.4300 83-5 Combined Chronic Toxicity/ Carcinogenicity: Rats A, B 43879801, 43597201870.4200 83-2B Carcinogenicity Mice A, B 43612001870.5265 84-2 Gene Mutation A, B

 41409801, 41388204, 41797903, 441388203, 41797902, 42015701, 4341797901

870.5300 84-2 In vitro Mammalian Cell Gene Mutation Test A, B 43394201, 43327304, 43327302

870.5375 84-2 In vitro Chromosome Aberration A, B 43327305, 43327303, 43327301

870.5385 84-2B In vivo chromosome aberration A, B

Mustonen, et al., 41478301, 42015741409805, 41870102, 41409806, 4142015701, 42015703, 42015706, 4342015701, 42015702, 42015705

870.5395 84-2 Micronucleus Assay A, B 41409804, 41870101
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 179 of 304

870.5450 84-2 Rodent Dominant Lethal Assay A, B 41409807, 41498101, 41409808, 41

43930501, 41498102

870.6200 81-8, 82-7, 83-1 Neurotoxicity Screening Battery A, B 43115201, 43293901

870.6300 83-6 Developmental Neurotoxicity A, B Datagap

870.7485 85-1 General Metabolism A, B 41737302

870.7600 85-3 Dermal Penetration and Absorption A, B Feldman. R. J. And Maibach, H. I. (197OCCUPATIONAL/RESIDENTIAL EXPOSURE875.1100 231 Estimation of Dermal Exposure at Outdoor Sites A, B 449722-01, 444598-01

875.1300 232 Estimation of Inhalation Exposure at Outdoor Sites A, B 449722-01, 444598-01

875.2200 132-1b Soil Residue Dissipation A, B 446557-01, 446557-04, 446557-03, 

RESIDUE CHEMISTRY860.1200 Directions for Use A, B Datagap

860.1300 171-4A Plant Metabolism A, B

00004666, 00004667, 00004669, 000004677, 00004680, 00004681, 0000004689, 00004693, 00004698, 0000004723, 00004960, 00004996, 0000074216, 00074217, 00102675, 0000102717, 00123973, Blacktop and  Feung, et al. (1972), 41991503, 424

42615601, 43290501, 43496101

860.1300 171-4B Livestock Metabolism A, B 00004705, 00068891, 42605201, 42
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 180 of 304

860.1340 171-4C Residue Analytical Method - Plant commodities A, B

00004720, 00033119, 00036171, 0000045364, 00045365, 00046125, 0000059027, 00059033, 00060113, 0000060872, 00060880, 00061012, 0000061017, 00061018, 00061645, 0000075715, 00075716, 00075719, 0000102710, 00102717, 00102719, 0000102862, 00102865, 00109535, 0000120057, 00121733, 00123269, 0000133938, 00136845, 00138635, 0000140092, 00156264, PP#6E2606 ((1964), Bontoyan (1985), Freed (1943691101, 43893701

860.1340 171-4C Residue Analytical Method - Livestock commodities A, B

00004701, 00004707, 00004719, 0000055485, 00066156, 00068011, 0000071787, 00078237, 00102713, 0000102816, 00102821, 00115509, 00Otto et al (1982), 44016501, 44016

860.1340 171-4C Residue Analytical Method - Water A, B 00035913, 00115509, 00121711, 00

et al (1982)

860.1380 171-4E Storage Stability - Plant commodities A, B

00136845, 00140092, 00145248, 4343879901, 43879902, 43879903, 4343886401, 43886402, 43886403, 4343886406, 43943101, 43963801, 4345245601

860.1380 171-4E Storage Stability - Livestock commodities A, B 44024801, 44967401

860.1380 171-4E Storage Stability - Water A, B 00035913, 00139511860.1400 171-4F Water, Fish, and Irrigated Crops - Irrigated Crops A, B 00052597, 00139511, Datagap
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 181 of 304

860.1400 171-4F Water, Fish, and Irrigated Crops - Fish and Shellfish A, B 00028443, 00035913, 00043759, 00

00115741, 43378801, 44135201, 44

860.1400 171-4F Water, Fish, and Irrigated Crops - Water A, B 00035913, 00038429, 00052597, 00

00118549, 42968501, 42968502

860.1480 171-4J

Meat, Milk, Poultry, Eggs - Milk andthe Fat, Meat, and Meat Byproducts ofCattle, Goats, Hogs, Horses, and Sheep

A, B 00004701, 00004707, 00004719, 00

00068893, 00102714, 44024801

860.1480 171-4J

Meat, Milk, Poultry, Eggs - Eggs andthe Fat, Meat, and Meat Byproducts ofPoultry

A, B 00102719

860.1500 171-4K Crop Field Trials (Root and Tuber Vegetables Group - Potatoes) A, B 00060876, 00102814, 00102862, 00

860.1500 171-4K

Crop Field Trials (Legume Vegetables(Succulent or Dried) Group - Soybeanseed)

A, B 43356301, 43356302, 43356303, 43

860.1500 171-4K

Crop Field Trials (Foliage of LegumeVegetables Group - Soybean forageand hay)

A, B 43356301, 43356302, 43356303, 43

860.1500 171-4K Crop Field Trials (Citrus - Grapefruits, Lemons, Oranges) A, B 00102605, 43870303, 00102879, 00

45462201, 00042526, 00102605, 0000163903, 43870303, 45462201, 45

860.1500 171-4K Crop Field Trials (Pome Fruits Group - Apples, Pears, Quinces) A, B 00102824, 43943101, 00102824, 43

860.1500 171-4K Crop Field Trials (Stone Fruits Group - Cherry, Peach, Plum/Fresh Prune) A, B 00088176, 43879902, 43879901, 43

860.1500 171-4K Crop Field Trials (Berries Group - Blueberries, Raspberries) A, B 00061010, 00061012, 43886403, 44
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 182 of 304

860.1500 171-4K Crop Field Trials (Tree Nut Group - Almond, Filbert, Pecan, Walnut) A, B 00088176, 44211901, 43963801, 43

860.1500 171-4K

Crop Field Trials (Cereal GrainsGroup - Barley, grain; Corn, field,grain; Corn, sweet (K+CWHR);Millet, grain; Oats, grain; Rice, grain;Rice, wild, grain; Rye, grain;Sorghum, grain; Wheat, grain)

A, B

00004610, 00036168, 00036169, 0000059025, 00059027, 00059029, 0000021755, 00022329, 00025383, 0043676801, 43686001, 43693702, 0000025330, 00161187, 00036169, 0000004594, 00120057, 43747901, 4300102719, 00102889, 00120057, 4343718002, 00022622, 00036168, 0000045369, 00046127, 00059029, 0000078482, 00090361, 00127226, 0043665202, 43676802, 43797901, 4344190302, Datagap

860.1500 171-4K

Crop Field Trials (Forage, Fodder, andStraw of Cereal Grains Group -Barley, haw and straw; Corn, field,forage, and stover; Corn, sweet, forageand stover; Millet, forage, hay, andstraw; Oat, forage, hay, and straw;Rice, straw; Rye, forage and straw;Sorghum, forage and stover; Wheat,forage, hay, and straw)

A, B

00036168, 00036171, 00059025, 0000022622, 00025383, 00028385, 0000075715, 00075724, 00102865, 0043676801, 43686001, 43693702, 0043747901, 43785901, 00102719, 043697801, 43718001, 43718002, 0000028200, 00042288, 00061010, 0000102712, 00120057, 00138635, 0043665201, 43665202, 43676802, 4344190301, 44190302, Datagap

860.1500 171-4K

Crop Field Trials (Grass Forage,Fodder, and Hay Group - Grass(pastures and rangeland) forage andhay)

A, B

00004485, 00028173, 00028200, 0000063507, 00090360, 00102712, 0000144791, 00147047, 43592101, 4343665203, 43665204, 43665205, 4343779503, 43779504
Appendix B

Data Supporting Guideline Requirements for the Reregistration of 2,4-D

REQUIREMENT Use Patterns CITATION(S)

Page 183 of 304

860.1500 171-4K

Crop Field Trials (MiscellaneousCommodities - Asparagus; AspiratedGrain Fractions; Cranberries; Grapes;Hops; Pistachios; Strawberries;Sugarcane)

A, B

00025338, 00060870, 43879905, 4300061010, 00061012, 43886402, 0043947901, 45245601, 45647101, 4543879904, 00102717, 00102812, 4300079738, 00102640, 00102794, 0043736101, 43736102

860.1520 171-4L

Processed Food/Feed (Apples; Barley;Citrus; Corn, field; Grape; Oats;Potato; Prunes; Rice; Rye; Sorghum;Soybean; Sugarcane; Wheat)

A, B

43943101, 43870302, 43709701, 4543879903, 43755402, 43709702, 0043755401, 43693701 

860.1850 165-1 Confined Rotational Crops A, B 43356002

OTHER840.1100 201-1 Droplet Size Spectrum A, B Reserved840.1200 202-1 Drift Field Deposition Evaluation A, B Reserved
Page 184 of 304

Appendix C. Technical Support Documents
Page 185 of 304

Appendix C. TECHNICAL SUPPORT DOCUMENTS

Additional documentation in support of this RED is maintained in the OPP docket, located

in Room 119, Crystal Mall #2, 1801 South Bell Street, Arlington, VA. It is open Monday through

Friday, excluding legal holidays, from 8:30 am to 4 pm.

The docket initially contained preliminary risk assessments and related documents as of

June 23, 2004. Sixty days later the first public comment period closed. The EPA then considered

comments, revised the risk assessment, and added the response to comments documents,

preliminary mitigation strategies, and the revised risk assessments to the docket on January 12,

2005. The second sixty day public comment period closed on March 14, 2005. The 2,4-D

Reregistration Eligibility Decision (RED), revised risk assessments, and response to comments

documents were made available in the summer of 2005.

All documents, in hard copy form, may be viewed in the OPP docket room or downloaded

or viewed via the Internet at the following site:

www.epa.gov/pesticides/reregistration

These documents include:

HED Documents:

1. 2,4-D. HED’s Revised Human Health Risk Assessment for the Reregistration Eligibility

Decision (RED) Revised to Reflect Public Comments. PC Code 030001; DP Barcode D316597. 

May 12, 2005.

2. 2,4-D. Revised Acute and Chronic Dietary Exposure Assessments Including Proposed

New Uses Hops and Potatoes for the Reregistration Eligibility Decision. April 18, 2005.

3. 2,4-D: 3rd Revised Occupational and Residential Exposure and Risk Assessment and

Response to Public Comments for the Registration Eligibility Decision (RED) Document (PC Code

030001, DP Barcode D316596). May 4, 2005.

4. 2,4-D: Response to Phase 5 Public Comments (PC Code 030001, DP Barcode D315562). 

June 7, 2005.

5. 2,4-D. Revised Acute and Chronic Dietary Exposure Assessments for the Reregisration

Eligibility Decision. October 13, 2004.

6. 2,4-D: Health Effects Division (HED) Metabolism Assessment Review Committee

(MARC) Decision Document-Revised. DP Barcodes D309452 Chemical I.D. No. 030001. Case No.

0073. Meeting date 9/3/03. October 13. 2004.

7. 2,4-D. Revisions to the Product and Residue Chemistry Chatpers of the Reregistration

Eligibility Decision; Reregistration Case no. 0073. Chemical I. D. No. 030001; DP Barcode No.

D309450 and D309451. October 12, 2004.

8. 2,4-D PC Code 030001, Case No. 0073 DP Barcode D309450 Reregistration Eligibility

Decision Revised Chemistry Considerations. October 12, 2004.
Page 186 of 304

9. 2,4-D Case 0073 Reregistration Eligibility Decision: Revised Product Chemistry

Considerations (DP Barcode D309451). October 12, 2004. 

10. 2,4-D - Phase 3 Toxicology Chapter Revision. December 9, 2004.

11. 2,4-D: Response to Public Comments [PC Code 030001, DP Barcode D307717]. 

December 16, 2004.

EFED Documents:

1. Revised Environmental Fate and Effects Division Revised Preliminary Risk Assessment

for the 2,4-Dichlorophenoxyacetic acid (2,4-D) Reregistration Eligibility Decision Document. 

October 28, 2004.

2. Revised EFED Revised Preliminary Risk Assesssment for the 2,4-D Reregistration

Eligibility Document. October 28, 2004.

3. 2,4-D - Response to Public Comments on the Revised EFED Science Chapter for the

Reregistration Eligibility Decision Document. October 28, 2004.

4. 2,4-D - Response to Public Comments from the San Francisco Department of the

Environment on the EFED Science Chapter for the Reregistration Eligibility Decision Document. 

November 1, 2004.
Page 187 of 304

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

Eligibility Decision (Bibliography) for 2,4-D
2,4-D Bibliography

Page 188 of 304

Toxicology References

Arbuckle, T. E., Schrader, S. M., Cole, D., et al. (1999). 2,4-Dichlorophenoxyacetic Acid Residues in

Semen of Ontario Farmers. Reproductive Toxicology 13: 421-429].

Bortolozzi, A. A.; Duffard, R. O.; and Evangelista De Duffard, A. M. (1999). Behavioral Alterations

Induced in Rats by a Pre- and Postnatal Exposure to 2,4-Dichlorophenoxyacetic Acid.

Neurotoxicology and Teratology, 21 (4): 451-465

Brusco, A.; Saavedra, J. P.; Garcia, G; et al. (1997). 2,4-Dichlorophenoxyacetic Acid Through

Lactation Induces Astrogliosis in Rat Brain.Mol. Chem. Neuropathol. 30, 175-185

Cavieres, M. F. Jaeger, J. and Porter, W. (2002). Developmental Toxicity of a Commercial Herbicide

Mixture in Mice: I. Effects on Embryo Implantation and Litter Size. Environmental Hlth Perspectives

110 (11), 1081-1085.

Duffard, R.; Garcia, G.; Rosso, S.; et al. (1996). Central Nervous System Myelin Deficit in Rats

Exposed to 2,4-Dichlorophenoxyacetic Acid Throughout Lactation. Neurotoxicology and Teratology,

18 (6):691-696 

Evangelista de Duffard, A. M. , N. De Aldrete, M., and Duffard, R. (1990)]. Changes in brain

serotonin and 5-hydroxyindoleacetic acid levels induced by 2,4-dichlorophenoxyacetic acid butyl

ester. Toxicol. 64, 265-270.

Faustini, A., Settimi, L., Pacifici, R., et al. (1996). Immunological changes among farmers exposed to

phenoxy herbicides: preliminary observations. Occupational and Environmental Medicine 53, 583-

585.

Garabrant, D. H. and Philbert, M. A. (2002). Review of 2,4-Dichlorophenoxyacetic Acid (2,4-D)

Epidemiology and Toxicology. Crit Rev Toxicol 32 (4): 233-57.

Garry, V. F.; Tarone, R. E.; Kirsch, I. R.; et al. (2001). Biomarker Correlations of Urinary 2,4-D

Levels in Foresters: Genomic Instability and Endocrine Disruption. Environmental Health

Perspectives (2001). 109 (5): 495-500.

Griffin, R. J. ; Godfrey, V. B.; Kim, Y-C ; et al. (1997). Sex-Dependent Differences in the

Disposition of 2,4-Dichlorophenoxyacetic Acid in Sprague-Dawley Rats, B6C3F1 Mice, and Syrian

Hamsters. Drug Metabolism and Disposition. The American Society for Pharmacology and

Experimental Therapeutics, Vol. 25, No. 9. 

Lee, K., Johnson, V., and Blakley, B. (2001). The Effect of Exposure to a Commercial 2,4-D

Formulation During Gestation on the Immune Response in CD-1 Mice. Toxicology: 165 (1): 39-49.

Sandberg, J. A. (1996). Distribution of 2,4-Dichlorophenoxyacetic Acid (2,4-D) in Maternal and Fetal

Rabbits. J. Toxicology and Environmental Health. 49: 497-509.

Arias, E (2003). Sister chromatid exchange induction by the herbicide 2,4-dichlorophenoxyacetic

acid in chick embryos. Ecotox and Environ Safety 55:338-343.
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Page 189 of 304

Amer, SM and Aly, FAE (2001). Genotoxic effect of 2,4-dichlorophenoxyacetic acid and its

metabolite 2,4-dichlorophenol in mouse. Mutat Res 494:1-12.

Charles, JM, Cifone, MA, Lawlor, T, Murli, H, Young, RR, Leeming, NM (2000). Evaluation of the

in vitro genetic toxicity of 4-(2,4-dichlorophenoxy) butyric acid. Mutat Res 472: 75-83.

Galloway, SM, Armstrong, MJ, Reuben, C, Colman, S, Brown, B, Cannon, C, et al. (1987). 

Chromosome aberrations and sister chromatid exchanges in Chinese hamster ovary cells: evaluation

of 108 chemicals. Environ Mol Mutagen 10:1-175, Suppl. 10.

Holland, NT, Duramad, P, Rothman, N, Figgs, LW, Blair, A, Hubbard, A, Smith, MT. (2002). 

Micronucleus frequency and proliferation in human lymphocytes after exposure to herbicide 2,4-

dichlorophenoxyacetic acid in vitro and in vivo. Mutat Res 512:165-178.

Madrigal-Bujaidar, E, Hernandez-Ceruelos, A, Chamorro, G (2001). Induction of sister chromatid

exchanges by 2,4-dichlorophenoxyacetic acid in somatic nd germ cells of mice exposed in vivo. 

Food and Chem Toxicol 39:941-946.

Mustonen, R, Kangas, J, Vuojolahti, P and Linnainmaa, K (1986). Effects of phenoxyacetic acid on

the induction of chromosome aberrations in vitro and in vivo. Mutagenesis, 4:241-245.

Venkov, P, Topashka-Ancheva, M, Georgieva, M, Alexieva, V, Karanov, E (2000). Genotoxic

effects of substituted phenoxyacetic acids. Arch Toxicol 74:560-566.

Waters, MD, Sandhu, SS , Simmons, VF, Mortelmans, KE Mitchell, AD, Jorgenson, Jones, DCL,

Valencia, R, Garrett, NE. (1982). Study of pesticide genotoxicity, in R.Fleck, A Hollaender (Eds),

Genetic Toxicology - An Agricultural Perspective, Plenum Press, New York, pp. 275-326.

Zeljezic, D and Garaj-Vrhovac,V (2004). Chromosomal aberrations, micronuclei and nuclear buds

induced in human lymphocytes by 2,4-dichlorophenoxyacetic acid pesticide formulation. Toxicol

200:39-47. 

Occupational and Residential References

2,4-D Smart Meeting , March 6, 2001, Industry Task Force II on 2,4-D Research Data and the USDA

Office of Pest Management Policy.

2,4-D Master Label, September 24, 2004, Industry Task Force II on 2,4-D Research Data and the

USDA Office of Pest Management Policy.

Abbott, et. al., 1987 “Worker Exposure to a Herbicide Applied with Ground Sprayers in the United

Kingdom”, AIHA Journal 48 (2): 167-175 

Bothwell, Max L. and Daley, Ralph J. “Selected Observations on the Persistence and Transport of

Residues from Aqua-Kleen 20 (2,4-D) Treatments in Wood and Kalamalka Lakes, B.C.” The

National Water Research Institute, Inland Waters Directorate, Pacific and Yukon Region, West

Vancouver, B.C. August, 1981.

Burnside, Oliver C. et al, Biologic and Economic Assessment of Benefits from Use of Phenoxy

Herbicides in the United States, NAPIAP Report Number 1-PA-96, November 1996
2,4-D Bibliography

Page 190 of 304

Crowell, Wendy J., November 1999, “Minnesota DNR Tests the Use of 2,4-D in Managing Eurasian

Watermilfoil.” Aquatic Nuisance Species Digest,, Volume 3, No. 4, pp 42-43.

Feldmann and Maibach, “Percutaneous Penetration of Pesticides and Herbicides in Man”, Toxicology

and Applied Pharmacology 28, 126-132 (1974)

Harris and Solomon, 1992, “Human Exposure to 2,4-D Following Controlled Activities on Recently

Sprayed Turf,” Journal of Environmental Science and Health, B27 (1), 9-22 (1992).

Industry Task Force II on 2,4-D Research Data, “EPA/SRRD and 2,4-D Task Force Lawn and Turf

Application Rate”, May 2, 2005.

Maroni et al./Chapter 6 -Phenoxyacetate Herbicides, Toxicology 143 (2000), 77-83.

Paris et. al. “Second Order Model to Predict Microbial Degradation of Organic Compounds in

Natural Waters”, Applied and Environmental Microbiology, Vol. 41, No. 3, March 1981, p. 603-609

USFS, September 20, 1998, 2,4-Dichlorophenoxyacetic acid Formulation - Human Health and

Ecological Risk Assessment Final Report, Prepared for the USFS by Syracuse Environmental

Research Associates, Inc.

U.S. EPA, August, 1997 Exposure Factors Handbook Volume I - General Factors. U.S.

Environmental Protection Agency, Office of Research and Development, EPA/600/P-95/002Fa.

U.S. EPA, February 10, 1998 Draft Standard Operating Procedures for Residential Exposure

Assessments. U.S. Environmental Protection Agency, Office of Pesticide Programs.

U.S. EPA, 1998. PHED Surrogate Exposure Guide, V1.1. U.S. Environmental Protection Agency,

Office of Pesticide Programs, August 1998.

U.S. EPA SAP, “Exposure Data Requirement for Assessing Risks from Pesticide Exposure of

Children”, SAP Meeting of March 8, 1999, page 60. 

U.S. EPA, 1999, “Use of Values from the PHED Surrogate Table and Chemical-Specific Data.” 

Science Advisory Council for Exposure, Policy.007, U.S. Environmental Protection Agency, Office

of Pesticide Programs.

U.S. EPA, August 7, 2000, "Agricultural Default Transfer Coefficients" Science Advisory Council

for Exposure, SOP 003.1, .U.S. Environmental Protection Agency, Office of Pesticide Programs.

U.S. EPA, July 5, 2000, “Standard Values for Daily Acres Treated in Agriculture” HED Science

Advisory Council for Exposure, Policy.009, U.S. Environmental Protection Agency, Office of

Pesticide Programs.

U.S. EPA, 8/9/2001, Quantitative Usage Analysis for 2,4-D.

U.S. EPA, December 5, 2001 “A Pilot Study to Determine the Water Volume Ingested by

Recreational Swimmers”, Paper Presented at the 2001 Annual Meeting of the Society of Risk

Analysis by Otis Evans et. al. of the U.S. EPA Office of Research and Development, National

Exposure Research Laboratory.

U.S. EPA, August 23, 2002, Master Label for the Reregistration of 2,4-Dichlorophenoxyacetic Acid

Uses Supported by the 2,4-D Industry and IR-4
2,4-D Bibliography

Page 191 of 304

U.S. EPA, March 18, 2003, Maximum Application Rates for 2,4-D Risk Assessments

U.S. EPA, May 1, 2003, 2,4-D Report of Hazard Identification And Review Committee; Author:

Linda Taylor, Ph.D., TXR NO. 0051866

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study received May 2, 1975 under 476-2156; prepared by Univ. of Nebraska,

submitted by Stauffer Chemical Co., Richmond, Calif.; CDL:009609-K) 

00022329 Grage, D.; Dietz, B.; Dietze, R.; et al. (1976) Sequential Appli- cations of

Eradicane 6.7-E (PPI) and 2,4-D (POES): Summary of Crop Residue Data on

Corn. (Unpublished study received Apr 20, 1976 under 476-2157; prepared in

cooperation with Morse Laboratories, Inc., submitted by Stauffer Chemical Co.,

Richmond, Calif.; CDL:224614-E) 

00022622 Woofter, D.; Appleby, A.P.; Watson, V.H.; et al. (1972) ?Chemical Sprays on

Corn, Sorghum and Wheat|. (Unpublished study received Jan 3, 1973 under

876-25; prepared in cooperation with Oregon State Univ. and others, submitted

by Velsicol Chemical Corp., Chicago, Ill.; CDL:005052-C) 

00025330 Suzuki, H.K.; Fenster, C.R. (1976) Dicamba: Residue Tolerance Peti- tion--

Proso Millet. (Unpublished study received Jan 24, 1979 under 9E2166; prepared

in cooperation with Univ. of Nebraska, submitted by Velsicol Chemical Corp.,

Chicago, Ill.; CDL: 097773-A) 

00025338 Klausen-Rogers, G.; Renfrow, J.; Slater, L.; et al. (1970) Residue Results:

?Dicamba|. (Unpublished study received Jun 15, 1973 under 1F1131; prepared

in cooperation with Del Monte Corp. and others, submitted by Velsicol

Chemical Corp., Chicago, Ill.; CDL:090907-F) 

00025383 Suzuki, H.K.; Behrens, R.; Kilmer, D. (1975) Residue Chemistry: ?Dicamba|.

(Unpublished study including report no. 404000, nos. 174, 176 and 179,

received Nov 18, 1976 under 876-255; prepared in cooperation with

International Research and Development Corp. and Univ. of Wisconsin,

submitted by Velsicol Chemical Corp., Chicago, Ill.; CDL:226930-A) 

00028173 Hoffman, C.; Haas, R.; Criswell, T.; et al. (1970) Grass: Project No. 404000.

(Unpublished study received Jun 15, 1970 under 876- 25; submitted by Velsicol

Chemical Corp., Chicago, Ill.; CDL: 004524-D) 

00028200 Tullos, B.; Martin, L.; Morse, R.; et al. (1975) Weedmaster Herbi- cide Residue

Data. (Unpublished study received Oct 2, 1975 un- der 876-203; prepared in

cooperation with Kerr Foundation and others, submitted by Velsicol Chemical

Corp., Chicago, Ill.; CDL:195015-A) 
2,4-D Bibliography

Page 201 of 304

00030692

Suzuki, H.K.; Whitacre, D.M.; Wellman, J.; et al. (1978) Residue Data: Banvel|.

(Unpublished study received Sep 14, 1979 under SD79-13; prepared in

cooperation with Craven Laboratories and others, submitted by state of South

Dakota for Velsicol Chemical Corp., Chicago, Ill.; CDL:241007-E) 

00028443 Duke, T. (1971) Technical Report on the Effect of 2,4-D Formula- tions on

Estuarine Organisms. (Unpublished study received Jul 13, 1971 under 1E1046;

prepared by U.S. Environmental Protection Agency, Gulf Breeze Laboratory,

submitted by U.S. Dept. of the Army, Office of the Chief of Engineers,

Washington, D.C.; CDL: 091865-H) 

00030697 Suzuki, H.K.; Whitacre, D.M.; Anderson, R.F.; et al. (1976) Resi- due Project

75-1-D, Banvel^(R)I: Corn-Harvest Aid. (Unpublished study received Aug 30,

1979 under 876-25; prepared in cooperation with International Research and

Development Corp. and ABC Laboratories, submitted by Velsicol Chemical

Corp., Chicago, Ill.; CDL:240896-A) 

00030701 Suzuki, H.K.; Whitacre, D.M.; Boudreaux, H.; et al. (1980) Weedmaster^(R)IHerbicide on Sugarcane: Residue Data and Processing Studies.

(Unpublished study received Apr 12, 1980 under 876- 203; prepared in

cooperation with International Research & Development Corp. and T. Lanaux &

Sons, submitted by Velsicol Chemical Corp., Chicago, Ill.; CDL:242414-B) 

00033119 Washington State University (1963) ?Residues of 2,4D in Apples and Pears|.

(Unpublished study received Dec 24, 1963 under 264-37; submitted by Union

Carbide Agricultural Products Co., Ambler, Pa.; CDL:001835-B) 

00035913 Gangstad, E.O.; Zimmerman, P.W.; Hitchcock, A.E.; et al. (1974) Aquatic-Use

Patterns for 2,4-D Dimethylamine and Integrated Control. By U.S. Dept. of the

Army, Office of the Chief of Engineers, Aquatic Plant Control Program.

Vicksburg, Miss.: U.S. Army Engineer, Waterways Experiment Station. (APCP

technical report 7; published study; CDL:096474-C) 

00036168 Bjerke, E.L.; Ervick, D.K.; Stymiest, C.; et al. (1973) A Residue Study of the

Disappearance of Picloram and 2,4-Dichlorophenoxy- acetic acid in Small Grain

following Application of Tordon Herbicide: GH-C 683. (Unpublished study

received Jul 3, 1975 under 6F1653; prepared in cooperation with South Dakota

State Univ. and others, submitted by Dow Chemical Co., Indianapolis, Ind.;

CDL:094498-C) 

00036169 Southwick, L.; Hartman, G.P.; Stritzke, J.; et al. (1975) A Residue Study of

Picloram and 2,4-D in Oats and Barley following Post- emergence Application

of Tordon^(R)I 202 Herbicide: GHP-912. (Unpublished study received Jul 3,

1975 under 6F1653; prepared in cooperation with Univ. of Montana and others,

submitted by Dow Chemical Co., Indianapolis, Ind.; CDL:094498-D) 
2,4-D Bibliography

Page 202 of 304

00036170 Southwick, L.; Behrens, R.; Hartman, G.P. (1975) A Residue Study of Picloram

and 2,4-Dichlorophenoxyacetic acid in Wheat follow- ing One, Two and Three

Years Use of Picloram and 2,4-D (Tor- don^(R)I 202 Mixture): GHP-913.

(Unpublished study received Jul 3, 1975 under 6F1653; prepared in cooperation

with Univ. of Minnesota and Univ. of Montana, submitted by Dow Chemical

Co., Indianapolis, Ind.; CDL:094498-E) 

00036171 Bjerke, E.L.; Dietrich, I.; Baker, L.O.; et al. (1975) A Residue Study of Picloram

and 2,4-D in Wheat and Barley following Post- emergence Application of

Tordon 22K Weed Killer plus Formula 40 Herbicide: GH-C 821. (Unpublished

study received Jul 3, 1975 under 6F1653; prepared in cooperation with Univ. of

Montana and Montana State Univ., submitted by Dow Chemical Co.,

Indianapolis, Ind.; CDL:094498-F) 

00037169 Marquardt, R.P.; Luce, E.N. (1961) A new basic procedure for determining

phenoxy acid herbicides in agricultural products. Journal of Agricultural and

Food Chemistry 9(4):266-270. (Also In unpublished submission received Dec 6,

1972 under 3G1339; submitted by Interregional Research Project No. 4, New

Brunswick, N.J.; CDL:093578-A) 

00038429 Smith, G.E.; Isom, B.G. (1967) Investigation of effects of large- scale

applications of 2,4-D on aquatic fauna and water quality. Pesticides Monitoring

Journal 1(3):16-21. (Also in unpublished submission received Jul 11, 1971

under 1E1046; submitted by U.S. Dept. of the Army, Washington, D.C.;

CDL:093359-Y) 

00042288 Grigsby, B.H.; Farwell, E.D. (1950) Some Effects of Herbicides on Pasture and

on Grazing Livestock. Michigan Agricultural Experiment Station Quarterly

Bulletin 32(3): 378-385. (Submitter ACD file no. HF-19; also in unpublished

submission received Oct 3, 1966 under unknown admin. no.; submitted by Dow

Chemical U.S.A., Midland, Mich.; CDL:106349-A) 

00042526 Meagher, W.G.; Phillips, R.L. (1966) Physiological Effects and Chemical

Residues Resulting from 2,4-TP and 2,4,5-TP Sprays used for Control of

Preharvest Fruit Drop in Pineapple Oranges. Progress rept., Jun 30, 1966.

(Unpublished study received Mar 4, 1974 under 4E1476; prepared by Univ. of

Florida, Citrus Experiment Station, submitted by Interregional Research Project

No. 4, New Brunswick, N.J.; CDL:093925-D) 

00043280 Whitney, E.W.; Montgomery, A.B.; Martin, E.C.; et al. (1968) The effects of a

2,4-D application on the biota and water quality in Currituck Sound, North

Carolina. Without title| ? (? ):13- 17. (Also in unpublished submission received

Aug 4, 1976 under 876-222; submitted by Velsicol Chemical Corp., Chicago,

Ill.; CDL:242936-D) 

00043759 Sikka, H.C. (1976) Fate of 2,4-D in Fish and Blue Crabs: Contract No.

DACW39-74-C-0068. (Syracuse Research Corp. for U.S. Army, Office of the

Chief of Engineers, Environmental Characterization Branch, MESL, Waterways

Experiment Station, unpublished study; CDL:099544-D) 
2,4-D Bibliography

Page 203 of 304

00045364 Swann, R.L.; Pettyjohn, M.A.; Bjerke, E.L. (1972) Determination of Residues of

2,4-D in Wheat, Barley and Oat Green Forage, Grain and Straw by Gas

Chromatography. Method ACR 72.8 dated May 12, 1972. (Unpublished study

received Jul 3, 1975 under 6F1653; prepared in cooperation with International

Research and Development Corp., submitted by Dow Chemical U.S.A.,

Midland, Mich.; CDL:094500-B) 

00045365 Bjerke, E.L. (1973) A Study of Extraction of Picloram and 2,4-D from Small

Cereal Grains: GH-C 680. (Unpublished study received Jul 3, 1975 under

6F1653; submitted by Dow Chemical U.S.A., Mid- land, Mich.; CDL:094500-

C) 

00045369 Bjerke, E.L.; Ervick, D.K. (1975) A Residue Study of Picloram and 2,4-D in

Milled Wheat Fractions: GH-C 798. (Unpublished study received Jul 3, 1975

under 6F1653; submitted by Dow Chemical U.S.A., Midland, Mich.;

CDL:094501-B) 

00046125 Yip, G. (1964) Herbicides and plant growth regulators: Determina- tion of

herbicides in oils. Journal of the Association of Official Analytical Chemists

47(6):1116-1119. (Also in unpublished submission received on unknown date

under 6F0459; submitted by U.S. Dept. of Agriculture, Agricultural Research

Service, unknown location; CDL:098165-I) 

00046127 Phillips, W.M.; Yip, G.; Finney, K.F.; et al. (1964) The Effects and Residue

Status of Applications of Amine and Ester; Applica- tions of 2,4-D at Three

Preharvest Growth Stages on Hard Red Winter Wheat. (Unpublished study

received on unknown date under 6F0459; prepared in cooperation with Kansas

State Univ., Agricultural Experiment Station, Dept. of Flour and Feed Milling

Industries and others, submitted by U.S. Dept. of Agriculture, Agricultural

Research Service, unknown location; CDL:098165-L) 

00052597 Frank, P.A. (1969) Residues of 2,4-D in Irrigation Water and Ir- rigated Crops.

(U.S. Dept. of Agriculture, Crops Protection Branch, unpublished study;

CDL:091863-D) 

00055485 Khajeh-Noori, K. (19??) Method for Analysis of Residues of N,N- Dimethyl2,4-dichlorophenoxyacetamide on Whole Fish. Undated method. (Unpublished

study received Nov 22, 1971 under 16133-1; prepared by Thornton

Laboratories, Inc., submitted by Clearwater Chemical Corp., Ft. Myers, Fla.;

CDL:015056-K) 

00055755 Whitney, E.W.; Montgomery, A.B.; Martin, E.C.; et al. (19??) The effects of a

2,4-D application on the biota and water quality in Currituck Sound, North

Carolina. ?Without Title| ? (? ):13-17. (Also in unpublished submission received

May 19, 1975 under 2E1221; submitted by U.S. Dept. of the Army,

Washington, D.C.; CDL:094080-J) 
2,4-D Bibliography

Page 204 of 304

00059025 Glas, R.D. (1975) Residues of Dowco 290 and 2,4-D in Wheat and Barley

following Postemergence Application of Lontrel 205 Herbicide: GH-C 836.

(Unpublished study received Nov 12, 1980 under 464-563; submitted by Dow

Chemical U.S.A., Midland, Mich.; CDL:099735-D) 

00059026 Gardner, R.C.; Bjerke, E.L. (1975) Residues of Dowco 290, 2,4-D and MCPA

in Green Forage, Straw and Grain of Wheat and Barley after Postemergence

Treatment with Lontrel Herbicides: GH-C 850. (Unpublished study received

Nov 12, 1980 under 464-563; submit- ted by Dow Chemical U.S.A., Midland,

Mich.; CDL:099735-E) 

00059027 Kutschinski, A.H. (1979) Residues of Dowco 290 and 2,4-D in Barley and

Wheat following Postemergence Application of Lontrel 205 Herbicide by

Ground vs Aerial Sprayer: GH-C 1208. (Unpublished study received Nov 12,

1980 under 464-563; submitted by Dow Chemical U.S.A., Midland, Mich.;

CDL:099735-F) 

00059028 Kutschinski, A.H. (1979) Residues of Dowco 290 and 2,4-D in Oats following

Postemergence Application of Lontrel 205 Herbicide: GH-C 1217.

(Unpublished study received Nov 12, 1980 under 464- 563; submitted by Dow

Chemical U.S.A., Midland, Mich.; CDL: 099735-G) 

00059029 Glas, R.D. (1978) Residues of 3,6-Dichloropicolinic acid and 2,4-D in Milling

and Malting Fractions following Postemergence Application of Lontrel 205

Herbicide to Wheat and Barley: GH-C 977. (Unpublished study received Nov

12, 1980 under 464-563; sub- mitted by Dow Chemical U.S.A., Midland,

Mich.; CDL:099735-H)

00059033 Kutschinski, A.H. (1979) Determination of Residues of 3,6-Dichloro- picolinic

acid and 2,4-D in Barley and Wheat by Gas Chromatography. Method ACR

79.5 dated Apr 18, 1979. (Unpublished study received Nov 12, 1980 under 464-

563; submitted by Dow Chemical U.S.A., Midland, Mich.; CDL:099735-L) 

00059034 Miller, P.W. (1975) Residues of 2,4-D and 2,4-Dichlorophenol in Milk from

Cows Fed 2,4-D in Conjunction with Dowco 290: GH-C 804. (Unpublished

study received Nov 12, 1980 under 464-563; submitted by Dow Chemical

U.S.A., Midland, Mich.; CDL:099736-A) 

00060111 American Cyanamid Company (1977) General Summary: Avenge in Wheat

Grain and Straw|. (Compilation; unpublished study received Apr 26, 1977 under

241-250; CDL:229617-A) 

00060113 Peterson, R.P. (1976) CL 84,777 Combination: Gas Chromatographic

Procedure for the Determination of 2,4-D Residues in Wheat. Method M-733

dated Oct 8, 1976. (Unpublished study received Apr 26, 1977 under 241-250;

submitted by American Cyanamid Co., Princeton, N.J.; CDL:229617-D) 

00060117 American Cyanamid Company (1975) General Summary: ?Studies to Determine Avenge and 2,4-D Residues in Barley Grain and Straw|. (Compilation;

unpublished study received Apr 26, 1977 under 241- 250; CDL:229616-A) 
2,4-D Bibliography

Page 205 of 304

00060120 Peterson, R.P. (1976) CL 84,777 Combination: Gas Chromatographic

Procedure for the Determination of 2,4-D Residues in Barley. Method M-738

dated Oct 8, 1976. (Unpublished study received Apr 26, 1977 under 241-250;

submitted by American Cyanamid Co., Princeton, N.J.; CDL:229616-D) 

00060870 Dow Chemical U.S.A. (1956) Residue Study on Samples from Washington and

California Trials: 2,4-D for Weed Control in Asparagus Cul- ture. (Unpublished

study received Jan 2, 1958 under PP0162; CDL:090188-K) 

00060872 Dow Chemical U.S.A. (1955?) Method of Analysis for 2,4-D on Treated

Asparagus. (Unpublished study received Jan 2, 1958 under PP0162;

CDL:092439-C) 

00060876 Florida Fruit & Vegetable Association (1960) The Results of Tests on the

Amount of Residue Remaining, Including a Description of the Analytical

Method Used: (2,4-D). (Unpublished study received Oct 12, 1963 under

PP0272; CDL:090295-B) 

00060880 University of California--Davis (19??) Analysis for Combined 2,4-D esters in

Potatoes. Undated method. (Unpublished study received Oct 12, 1963 under

PP0272; prepared by Agricultural Extension Service, Dept. of Agronomy,

submitted by Florida Fruit & Vegetable Association, Orlando, Fla.;

CDL:090295-G) 

00061010 National Agricultural Chemical Association (1965?) The Results of Tests on the

Amount of Residue Remaining, Including a Description of the Analytical

Method Used: (2,4-Dichlorophenoxyacetic acid). (Compilation; unpublished

study received May 15, 1967 under 8F0670; CDL:091172-AL) 

00061012 National Agricultural Chemical Association (1967) Summary of Residues.

(Compilation; unpublished study received May 15, 1967 un- der 8F0670;

CDL:091172-AN) 

00061014 Dow Chemical Company (1959) Analytical Method: Determination of Trace

Amounts of 2,4-Dichlorophenoxyacetic acid in Sugar Cane Juice. Method no.

MLE.59.4 dated Apr 23, 1959. (Unpublished study received May 15, 1967

under 8F0670; submitted by National Agricultual Chemical Association,

unknown location; CDL: 091172-AR) 

00061016 Dow Chemical Company (1964) Determination of 2,4-Dichlorophenoxya- cetic

acid in Peanut Hay and Immature Peanut Vines. Method no. MLE.64.16 dated

Aug 20, 1964. (Unpublished study received May 15, 1967 under 8F0670;

submitted by National Agricultural Chemical Association, unknown location;

CDL:091172-AT) 

00061017 Dow Chemical Company (1964) Analytical Method: Determination of 2,4-

Dichlorophenoxyacetic acid in Peanuts. Method no. MLE.64.21 dated Apr 17,

1964. (Unpublished study received May 15, 1967 under 8F0670; submitted by

National Agricultural Chemical Association, unknown location; CDL:091172-

AU) 
2,4-D Bibliography

Page 206 of 304

00061018 Marquardt, R.P.; Luce, E.N. (1955) Determination of 2,4-Dichlorophenoxyacetic acid (2,4-D) in grain and seed. Agricultural and Food Chemistry

3(1):51-53. (Also In unpublished submission received May 15, 1967 under

8F0670; submitted by National Agricultural Chemical Association, unknown

location; CDL:091172-AV) 

00061645 Munro, H.E. (1972) Determination of 2,4-Dichlorophenoxyacetic acid and

2,4,5-Trichlorophenoxyacetic acid in tomato plants and other commercial crops

by microcoulometric gas chromatography. Pesti- cide Science 3(4):371-377;

taken from Weed Abstracts, 1973 22(2):38. (Abstract no. 376).

(Also~In~unpublished submission received Dec 9, 1974 under 33652-1;

submitted by Chemie Linz AG, Chemie, Austria; CDL:230516-U) 

00063507 Colorado. Department of Agriculture (1979) Residue Test No. 1734: Range

Grass from York, Nebraska. (Unpublished study; CDL: 244533-J) 

00066156 Duffy, J.R.; Shelfoon, P. (1967) Determination of 2,4-D and its butoxyethanol

ester in oysters by gas chromatography. Journal of the Association of Official

Analytical Chemists 50(5):1098- 1102. (Also~In~unpublished submission

received Aug 4, 1976 under 876-222; submitted by Velsicol Chemical Corp.,

Chicago, Ill.; CDL:229171-E) 

00068011 Diamond Shamrock Agricultural Chemicals (1975) Residue Studies in Grass

and Hay. (Compilation; unpublished study, including published data, received

Nov 19, 1980 under unknown admin. no.; CDL:244821-A) 

00068889 Kutschinski, A.H.; Bates, T.W.; Swann, R.L. (1971) Residues of 2,4-D in

Sugarcane and Its Factory Products Resulting from Applications of Amine or

Ester Formulations of the Herbicides. Final rept. (Unpublished study received

Oct 9, 1971 under 8F0670; prepared by Dow Chemical Co. in cooperation with

International Research and Development Corp., submitted by National

Agricultural Chemicals Association, Industry Task Force on Phenoxy Herbicide

Tolerances, Washington, D.C.; CDL:091173-D) 

00068891 Miller, P.W.; Jensen, D.J. (1971) Identification of 2,4,6-Tri- chlorophenol and

2,6-Dichlorophenol Residues in Milk from Cows Fed 2,4-

Dichlorophenoxyacetic acid. (Unpublished study re- ceived Oct 9, 1971 under

8F0670; prepared by Dow Chemical Co., submitted by National Agricultural

Chemicals Association, Industry Task Force on Phenoxy Herbicide Tolerances,

Washington, D.C.; CDL:091173-G) 

00068892 Miller, P.W.; Jensen, D.J.; Gentry, W.M. (1971) Residues of 2,4-

Dichlorophenoxyacetic acid and 2,4-Dichlorophenol in Tissues of Beef Calves

Fed 2,4-D. Final rept. (Unpublished study received Oct 9, 1971 under 8F0670;

prepared by Dow Chemical Co., submitted by National Agricultural Chemicals

Association, Industry Task Force on Phenoxy Herbicide Tolerances,

Washington, D.C.; CDL:091173-H) 
2,4-D Bibliography

Page 207 of 304

00068893 Jensen, D.J.; Miller, P.W.; Palmer, J.S. (1971) Residues of 2,4-

Dichlorophenoxyacetic acid and 2,4-Dichlorophenol in Tissues of Sheep Fed

2,4-D. (Unpublished study received Oct 9, 1971 under 8F0670; prepared by

Dow Chemical Co. in cooperation with U.S. Agricultural Research Service,

Animal Disease and Parasite Research Div., submitted by National Agricultural

Chemicals Association, Industry Task Force on Phenoxy Herbicide Tolerances, Washington, D.C.; CDL:091173-I) 

00071787 Toetz, D. (1976) Residues of 2,4-D in Flesh of Selected Fish Species in Lake

Fort Cobb as a Result of Herbicide Use on Eurasian

Watermilfoil~Myriophyllum spicatum. (Oklahoma State Univ., School of

Biological Sciences, Research Foundation for U.S. Dept. of the Interior, Bureau

of Reclamation; unpublished study; CDL:099179-D) 

00073273 Anon. (1979) A Comparison of Dicamba Dimethylamine Salt Emulsifiable

Concentrate with Dicamba Acid Granules in Terms of Stand Reduction and

Residues. (Reports by various sources; unpublished study received Nov 3, 1980

under OK 80/13; submitted by Oklahoma, Dept. of Agriculture, Oklahoma City,

Okla.; CDL: 243740-A) 

00074214 Feung, C.; Hamilton, R.H.; Mumma, R.O. (1975) Metabolism of 2,4-

dichlorophenoxyacetic acid. VII. Comparison of metabolites from five species

of plant callus tissue cultures. Journal of Agri- cultural and Food Chemistry

23(3):373-376. (Also in unpublished submission received Apr 14, 1981 under

0F2404; submitted by Dow Chemical Co., Indianapolis, Ind.; CDL:070006-D) 

00074215 Feung, C.; Hamilton, R.H.; Mumma, R.O. (1973) Metabolism of 2,4-dichlorophenoxyacetic acid. V. Identification of metabolites in soybean callus

tissue cultures. Journal of Agricultural and Food Chemistry 21(4):637-640.

(Also in unpublished submission received Apr 14, 1981 under 0F2404;

submitted by Dow Chemical Co., Indianapolis, Ind.; CDL:070006-E) 

00074216 Feung, C.; Hamilton, R.H.; Witham, F.H. (1971) Metabolism of 2,4-

dichlorophenoxyacetic acid by soybean cotyledon callus tissue cultures. Journal

of Agricultural and Food Chemistry 19(3):475, 479. (Also in unpublished

submission received Apr 14, 1981 under 0F2404; submitted by Dow Chemical

Co., Indianapolis, Ind.; CDL:070006-F) 

00074217 Hamilton, R.H.; Hurter, J.; Hall, J.K.; et al. (1971) Metabolism of 2,4-

dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid by bean

plants. Journal of Agricultural and Food Chemistry 19(3):480-483.

(Also~In~unpublished submission received Apr 14, 1981 under 0F2404;

submitted by Dow Chemical Co., Indianapolis, Ind.; CDL:070006-G) 

00074219 Lokke, H. (1975) Analysis of free and bound chlorophenoxy acids in cereals.

Bulletin of Environmental Contamination & Toxicology 13(6):730-736.

(Also~In~unpublished submission received Apr 14, 1981 under 0F2404;

submitted by Dow Chemical Co., Indianapolis, Ind.; CDL:070006-J) 
2,4-D Bibliography

Page 208 of 304

00075198 Carlile, B.L. (1968) Degradation and Depletion of Herbicides in Drainage

Waters and Accumulation of Residues in Crops Irrigated with Treated Water:

Annual Report--2,4-D and Silvex. (Battelle Memorial Institute for U.S. Dept. of

Agriculture; unpublished study; CDL:090913-D) 

00075715 Velsicol Chemical Corporation (1981) ?Residues in Corn|. Includes undated

method AM-0691. (Compilation, unpublished study received Jun 12, 1981

under 876-25; CDL:245471-B) 

00075716 Velsicol Chemical Corporation (1981) ?Residues in Wheat|. In- cludes undated

method AM-0691. (Compilation; unpublished study received Jun 12, 1981

under 876-25; CDL:245471-C) 

00075719 Velsicol Chemical Corporation (1981) ?Determination of Banvel and Dicamba

in Sorghum|. (Compilation; unpublished study received Jun 12, 1981 under 876-

25; CDL:245471-F) 

00075724 Velsicol (1981) (Determination of Banvel and Dicamba in Various Crops).

Includes method AM-0691 dated Jul 25, 1979. (Compila- tion; unpublished

study received Jun 22, 1981 under CO 81/11; CDL:245581-A) 

00078237 Bjerke, E.L.; Herman, J.L.; Miller, P.W.; et al. (1971) A Residue Study of

Phenoxy Herbicides in Milk and Cream. (Unpublished study received on

unknown date under 1E1123; prepared by Dow Chemical U.S.A., submitted by

Interregional Research Project No. 4, New Brunswick, N.J.; CDL:098798-A) 

00078482 Montana, Department of Agriculture (1974) ?Residue Tests for Picloram in

Grains|. (Compilation; unpublished study received on unknown date under

4E1489; CDL:093948-F) 

00079738 Velsicol Chemical Corporation (1981) Sugarcane Residue Studies.

(Compilation; unpublished study received Sep 11, 1981 under 876- 25;

CDL:070319-D) 

00088176 Interregional Research Project Number 4 (1978) ?Residues Study of Envy 2,4-D

on Stone Fruit|. (Compilation; unpublished study re- ceived Nov 18, 1981 under

2E2606; CDL:070506-A) 

00090360 Klingman, D.L.; Gordon, C.H.; Yip, G.; et al. (1966) Residues in the forage and

in milk from cows grazing forage treated with esters of 2,4-D. Weeds 14(2):164-

167. (Also~In~unpublished submission received May 31, 1966 under 6F0459;

submitted by U.S. Dept. of Agriculture, Agricultural Research Service, unknown address; CDL:090505-A) 

00090361 Hilton, J.L.; Phillips, W.M.; Shaw, W.C. (1960) A Summary of the Effects of

Amine and Ester Formulations of 2,4-Dichlorophenoxy- acetic Acid ?2,4-D| on

Small Grains, Including the Status of Residues When 2,4-D is Applied to the

Crop at Various Stage of Growth: Line Project No. CR FL-16. (U.S.

Agricultural Research Service, Crops Research Div.; unpublished study;

CDL:090505-C) 
2,4-D Bibliography

Page 209 of 304

00102605 Phillips, R. (1970) 2,4-D--Oranges and Grapefruit--CES (Lake Alfred) 1969.

(Unpublished study received Sep 28, 1970 under 359-177; prepared by Univ. of

Florida, Dept. of Food Science, Pesticide Research Laboratory, submitted by

Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL:026724-A) 

00102640 National Agricultural Chemicals Assoc. (1970) (2,4-D: Residues in Sugarcane).

(Compilation; unpublished study received Jan 18, 1971 under 8F0670;

CDL:091176-A) 

00102675 Canny, M.; Markus, K. (1960) The breakdown of 2,4-dichlorophenoxy- acetic

acid in shoots and roots. Australian J. Biol. Sci. 13 (4):486-502. (Also In

unpublished submission received Sep 12, 1968 under 8F0670; submitted by

National Agricultural Chemicals Assoc., Industry Task Force on Phenoxy

Herbicide Tolerances, Washington, DC; CDL:092089-L) 

00102676 National Agricultural Chemicals Assoc. (1968) (Phenoxy Herbicides: Residues

in Various Crops). (Compilation; unpublished study received Sep 12, 1968

under 8F0670; CDL:092089-O) 

00102679 Luckwill, L.; Lloyd-Jones, C. (1960) Metabolism of plant growth regulators I.

2,4-dichlorophenoxyacetic acid in leaves of red and of black currant. II.

Decarboxylation of 2,4-dichlorophen- oxyacetic acid in leaves of apple and

strawberry. Ann. Appl. Biol. 48(3):613-636. (Also In unpublished submission

received Sep 12, 1968 under 8F0670; submitted by National Agricultural

Chemicals Assoc., Industry Task Force on Phenoxy Herbicide Tol- erances,

Washington, DC; CDL:092089-AC) 

00102710 Florida Fruit & Vegetable Assoc. (1960) (Analyses for 2,4-D Residue in

Potatoes). (Compilation; unpublished study received Sep 26, 1960 under

PP0272; CDL:092551-D) 

00102712 Gentry, W. (1971) Residues of 2,4-Dichlorophenoxyacetic Acid, 2,4,5-

Trichlorophenoxyacetic Acid, and 2-(2,4,5-Trichloro- phenoxy)propionic Acid

in Grass Treated with Phenoxy Herbicides. (Unpublished study received Sep 7,

1973 under 8F0670; prepared by Dow Chemical Co., submitted by National

Agricultural Chemicals Assoc., Industry Task Force on Phenoxy Herbicide

Tolerances, Washington, DC; CDL:092965-C) 

00102713 National Agricultural Chemicals Assoc. (1973) Discussion of Anal- yses for

Residues of 2,4-D and 2,4-Dichlorophenol in Animal Tissues, July 1973.

Summary of study 092142-AD. (Compilation; unpublished study received Sep

7, 1973 under 8F0670; CDL: 092965-D) 

00102714 National Agricultural Chemicals Assoc. (1973) Discussion of Anal- yses for

Residues of 2,4-D and 2,4-Dichlorophenol in Milk, July 1973. (Compilation;

unpublished study received Sep 7, 1973 under 8F0670; CDL:092965-F) 
2,4-D Bibliography

Page 210 of 304

00102717 Crabtree, G.; Sheets, W.; Montgomery, M.; et al. (1974) Residue Study: 2,4-D

for Control of Broadleaf Weeds in Strawberries. (Unpublished study received on

unknown date under 5E1544; pre- pared by Oregon State Univ., submitted by

Interregional Research Project No. 4, New Brunswick, NJ; CDL:094206-A) 

00102719 National Agricultural Chemicals Assoc. (1975) Summary of Additional Residue

Data for 2,4-D in Sorghum, Poultry and Eggs, and Discussion on Residues in/on

Forage Grasses. (Compilation; unpublished study received Jul 16, 1975 under

8F0670; CDL: 094530-A) 

00102737 Honse, C.; Yoh, J.; Moye, H.; et al. (1973) (Alkanolamine Salt of 2,4-D:

Residues in Organs). (Unpublished study received Sep 25, 1975 under 6E1678;

prepared by Univ. of Florida, Pesticide Research Laboratory, submitted by

Interregional Research Project No. 4, New Brunswick, NJ; CDL:097352-B) 

00102760 Rawls, C. (1968) The Accumulation and Loss of Field-applied Butoxy- ethanol

Ester of 2,4-dichlorophenoxyacetic Acid in Eastern Oysters, ... and Soft-shelled

Clams, Mya arenaria. (Unpublished study received Jan 5, 1972 under 2E1221;

prepared by Univ. of Maryland, Natural Resources Institute, Chesapeake

Biological Laboratory, submitted by U.S. Dept. of the Army, Washington, DC;

CDL:097882-Z) 

00102788 Bartley, T.; Gangstad, E. (1975) Dissipation of Residues of 2,4-D in Irrigation

Canals. (U.S. Dept. of the Interior, Bureau of Reclamation, Office of the Chief

Engineer, Division of Research and U.S. Dept. of the Army, Office of the Chief

of Engineers, Directorate of Civil Works, Planning Div.; unpublished study;

CDL:097921-A) 

00102794 Kutschinski, A. (1972) Residues of 2,4-D in Louisiana Sugarcane Resulting

from Multiple Applications of Amine Formulations In- cluding a Late Summer

Treatment: GH-C 512. (Unpublished study received Dec 6, 1973 under 464-1;

submitted by Dow Chemical U.S.A., Midland, MI; CDL:101303-A) 

00102812 Reasor Hill Corp. (1960) ?Residues of 2,4-D in Strawberries and Cranberries|.

(Compilation; unpublished study received Feb 27, 1961 under 347-136;

CDL:120079-A) 

00102814 Zweig, G. (1962) Letter sent to J. McLean dated Nov 27, 1962 ?Re- port of

analysis for 2,4-D in potatoes|. (Unpublished study received Dec 17, 1962 under

unknown admin. no.; prepared by Univ. of California--Davis, Presticide Residue

Research, sub- mitted by Chemical Machines, Winnipeg, Canada; CDL:120204-

A) 

00102815 Brannock, D.; Freed, V. (1965) Analysis of Pears and Apples for Residues of

2,4-D from Dacamine-D. (Unpublished study received May 18, 1965 under

677-200; prepared by Oregon State Univ., Dept. of Agricultural Chemistry,

submitted by Diamond Shamrock Agricultural Chemicals, Cleveland, OH;

CDL:120205-A) 
2,4-D Bibliography

Page 211 of 304

00102816 Dow Chemical Co. (1955?) Studies on Raw Agricultural Commodities for

Residues of 2,4-Dichlorophenoxyacetic Acid (2,4-D). (Un- published study

received on unknown date under unknown admin. no.; CDL:120208-A) 

00102821 Boyce Thompson Institute for Plant Research, Inc. (1962) Residues of 2,4-D in

Milk from Cows Grazing on Sprague Pastures. (Un- published study received

Mar 22, 1962 under unknown admin. no.; submitted by Rhone-Poulenc, Inc.,

Monmouth Junction, NJ; CDL: 122170-A) 

00102824 Legault, R.; Benson, N.; Reynolds, D.; et al. (1963) Pesticide Res- idue

Analysis. (Unpublished study received 1964 under 264-37; prepared by

Washington State Univ., Dept. of Agricultural Chem- istry, submitted by Union

Carbide Agricultural Products Co., Inc., Research Triangle Park, NC;

CDL:122187-A) 

00102833 Rhone-Poulenc, Inc. (1964) Use of Weedez Bar (2,4-D) in Grape Vineyards--

Application to USDA for Registration on no Residue Basis. (Unpublished study

received Mar 23, 1964 under 359- EX-42; CDL:125194-B) 

00102862 Chemical Machines (1964) ?2,4-D: Residues in Potatoes|. (Compi- lation;

unpublished study received Mar 24, 1964 under 3462-8; CDL:221908-B) 

00102865 Leng, M.; Jensen, D.; Miller, P. (1973) Residues of 2,4-D in Field Corn and

Sweet Corn from Preemergence or Postemergence Treatments with the

Herbicide. (Unpublished study received Mar 4, 1976 under 464-201; submitted

by Dow Chemical U.S.A., Midland, MI; CDL:223616-A) 

00102879 Bice, J. (1961) Physiological Effect of 2,4-D on Lemons. (Unpub- lished study

received Jun 15, 1967 under 5202-18; submitted by Brogdex Co., Pomona, CA;

CDL:230582-A) 

00102889 Wisconsin Alumni Research Foundation (1969) Assay Report: W.A.R.F. No.

8110601-630. (Unpublished study received Oct 5, 1976 under 11275-2;

submitted by Guth Corp., Naperville, IL; CDL:235811-A) 

00109535 Velsicol Chemical Corp. (1982) ?Dicamba: Residues in Cows & Other

Subjects|. (Compilation; unpublished study received Aug 6, 1982 under 876-

168; CDL:248024-A) 

00115499 Dow Chemical Co. (1972) Amendment to PP 1F1102 Requesting Toler- ances

for Residues of ... (2,4,5-T). (Compilation; unpublished study received Jul 21,

1972 under 1F1102; CDL:090864-A) 

00115509 National Agricultural Chemicals Assoc. (1967) (Study: 2,4-D Resi- due in

Crops, Animal Tissue of Animal Products). (Compilation; unpublished study

received Sep 16, 1968 under 8F0669; CDL: 092964-Q) 
2,4-D Bibliography

Page 212 of 304

00115515 Dow Chemical Co. (1971) Study: 2,4,5-T Residues in Animals and Se- lected

Crops|. (Compilation; unpublished study received Sep 29, 1971 under 1F1102;

CDL:093415-A) 

00115741 Otto, N. (1982) Letter sent to Chief, Applied Sciences Branch dated Sep 8,

1982: Herbicidal residues and environmental effects re- sulting from the

experimental application of two 2,4-D formula- tions to control eurasian

watermilfoil. (U.S. Bureau of Recla- mation, Engineering and Research Center;

unpublished study; CDL: 248613-B) 

00115793 Ciba-Geigy Corp. (1977) Residues of Ametryn and 2,4-D Amine in or on

Sugarcane from Single and Multiple Applications--Louisiana. (Compilation;

unpublished study received Jan 16, 1978 under 100- 473; CDL:232676-A) 

00118549 Amchem Products, Inc. (1971) Fenac Residue Data--Total Water Treat- ment.

(Compilation; unpublished study received Jul 7, 1972 under 2F1213;

CDL:091039-T) 

00120057 National Agricultural Chemicals Assoc. (1970) The Results of Tests on the

Amount of Residue Remaining, Including a Description of the Analytical

Method Used: (2,4-Dichlorophenoxyacetic Acid). (Compilation; unpublished

study received Jan 18, 1971 under 8F0670; CDL:091174-A) 

00121711 Washington, Dept. of Game (1967) ?DDT: Residues in Seafood|. (Compilation;

unpublished study received 1967 under 4F0419; CDL:092706-A) 

00121733 Thompson Chemicals Corp. (19??) Method: ?Residues of Phenoxyacids and

Their Amine Salts in Apples and Other Crops|. (Unpublished study received Apr

3, 1967 under 7F0589; CDL:092877-A) 

00123269 Interregional Research Project No. 4 (1973) ?2,4-D Residues in Asparagus and

Other Subjects|. (Compilation; unpublished study received Mar 1, 1974 under

4E1475; CDL:093923-A) 

00123973 U.S. Fish and Wildlife Service (1972) Metabolism of Pesticides: ?2,4-D|.

(Unpublished study received 1972 under 4G1487; CDL: 093950-A) 

00126684 PBI-Gordon Corp. (1982) ?Ultra-Sulv (2,4-D) Residues in Wheat and Corn and

Rate of Decline in Soil|. (Compilation; unpublished study received Apr 1, 1983

under 2217-703; CDL:249863-G) 

00127226 U.A. Agricultural Research Service (1961) ?Residues: 2,4-D|. (Compilation;

unpublished study received Mar 16, 1964 under 6F0459; CDL:092748-A) 

00127273 PBI-Gordon Corp. (1982) Residues: (MCPP--Soil and Other Subjects).

(Compilation; unpublished study received Apr 1, 1983 under 2271-EX-3;

CDL:071501-Z) 
2,4-D Bibliography

Page 213 of 304

00127823 Velsicol Chemical Co. (1981) Hawaiian Sugarcane Residue Data: ?Banvel|.

(Compilation; unpublished study received Apr 15, 1983 under 876-25;

CDL:249983-A) 

00128778 Uniroyal Chemical (1981) Residue: ?2,4-D Amine|. (Compilation; unpublished

study received Jun 27, 1983 under 400-390; CDL: 250616-A) 

00133938 Stauffer Chemical Co. (1976) Residue Chemistry Data: ?Eradicane 6.7-E and

Other Chemicals in Corn|. (Compilation; unpublished study received Apr 20,

1976 under 476-2157; CDL:224095-A) 

00136845 Interregional Research Project No. 4 (1974) ?Residue Levels of 2,4-

Dichlorophenoxyacetic Acid and 2,4-Dichlorophenol in Red Potato Tubers|.

(Compilation; unpublished study received 1974 under 1E1122; CDL:093432-A) 

00136848 U.S. Dept. of the Interior (1962?) Residues: Method of Analysis of 2,4-D in

Water and Crop Plants. (Compilation; unpublished study received Jan 22, 1971

under 1E1136; CDL:093444-A) 

00138635 Velsicol Chemical Corp. (1983) The Results of Tests on the Amount of Residue

Remaining, Including a Description of the Analytical Method Used: ?Dicamba

and 5-Hydroxy Dicamba Residue in Vege- tables, Forage Crops, Legumes,

Cottonseed and Cottonseed Frac- tions and Grains|. (Compilation; unpublished

study received Feb 2, 1984 under 876-449; CDL:072332-A) 

00139059 California. (1975) ?Residue of 2,4-Dichlorophenoxyacetic Acid Iso- propyl

Ester in Oranges|. (Compilation; unpublished study re- ceived Feb 29, 1984

under CA 83/69; CDL:252533-A) 

00139511 U.S. Dept. of the Interior (1973) ?Residue Studies: 2,4-D: Crops|. (Compilation;

unpublished study received Apr 21, 1983 under 3E2876; CDL:071564-F) 

00139951 International Research and Development Corporation (19??) Determi- nation of

Residues of 2,4 Dichlorophenoxyacetic Acid (2,4-D) in Asparagus-gas

Chromatography. Undated method IRDC 6. (Un- published study received Jan

11, 1971 under 1F1131; submitted by Velsicol Chemical Corp., Chicago, Ill.;

CDL:091953-P) 

00140032 Union Carbide Agricultural Products Company, Incorporated (1965?)

Analytical Methods. (Unpublished study received Apr 19, 1968 under 264-EX30G; CDL:123220-E) 

00140092 National Agricultural Chemicals Assoc. (1970) Residue Studies on Sugarcane.

(Compilation; unpublished study received Jul 19, 1973 under 8F0670;

CDL:092966-A) 

00144791 Uniroyal Chemical (1985) DED-WEED SULV Residues in Pasture Grass and

Wheat Forage. Unpublished study. 14 p. 
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00145248 Velsicol Chemical Corp. (1984) Foliar Absorption, Metabolism and

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00147047 PBI Gordon Corp. (1984) Residue Analysis. Unpublished study. 25 p. 

00156264 Interregional Research Project No. 4 (1985) The Results of Tests on the Amount

of 2,4-D Residues Remaining in or on Soybeans Includ- ing a Description of the

Analytical Method Used. Unpublished compilation. 62 p. 

00161187 Interregional Research Project No. 4 (1977) The Results of Tests on the Amount

of Residues 2,4-D and its Metabolite Remaining in or on Millet Including a

Description of the Analytical Method Used. Unpublished compilation. 10 p. 

00163903 FMC Corp. (1986) Freshgard 26 Product Data: Residue Chemistry Data.

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40881401 Baron, J. (1988) 2,4-D--Magnitude of Residue on Rasberry: Laborato- ry

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41991503 Smith, G. (1991) Metabolism of 14 Carbon-(2,4-Dichlorophenoxy) Acetic Acid,

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42423101 Puglis, J.; Smith, G. (1992) Metabolism of Uniformly Ring Labeled ?carbon 14|

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42439701 Puvanesarajah, V. (1992) Metabolism of Uniformly ?carbon 14|-Ring Labeled

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42605201 Puvanesarajah, V.; Bliss, M. (1992) Metabolism of Uniformly Ring Labeled

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42615601 Puvanesarajah, V.; Ilkka, D. (1992) Metabolism of Uniformly (carbon 14)-Ring

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42749701 Guo, M.; Stewart, S. (1993) Metabolism of Uniformly (carbon 14)-Ring

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Army Corps of Engineers. Unpublished study prepared by Rhone-Poulenc Ag

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42968502 Rhone-Poulenc Ag Co. (1993) Miscellaneous Data on Residues and Persistence

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43160201 Guo, M.; Stewart, S. (1994) Supplemental Data for the Study, Metab- olism of

Uniformly (Carbon 14)-Ring Labeled 2, 4-Dichlorophen- oxyacetic Acid in

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43289301 James, J. (1994) Radiovalidation of EN-CAS Method ENC-2/93 for the

Determination of 2,4-Dichlorophenoxyacetic Acid (2,4-D) in/on Wheat Forage,

Straw, and Grain Treated with (Phenyl (U)(carbon 14))-2,4-Dichlorophenoxy

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Unpublished study prepared by EN-CAS Analytical Labs. 211 p. 

43290501 Wu, D. (1994) Metabolism of (carbon 14)-2,4-D IPE in Stored Lemons-Nature

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43356002 Burnett, T.; Ling, K. (1994) Confined Rotational Crop Study on Uniformly

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43356301 Carringer, R. (1994) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Soybeans Following Ground Application with

2,4-D Acid: Lab Project Number: 93-0022-0227: AA930227. Unpublished

study prepared by American Agricultural Services, Inc. and EN-CAS Analytical

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43356302 Carringer, R. (1994) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Soybeans Following Ground Application with

2,4-D 2-Ethylhexyl Ester: Lab Project Number: 93-0022-0226: AA930226.

Unpublished study prepared by American Agricultural Services, Inc. and ENCAS Analytical Labs. 450 p. 

43356303 Carringer, R. (1994) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Soybeans Following Ground Application with

2,4-D Dimethylamine Salt: Lab Project Number: 93-0022-0225: AA930225.

Unpublished study prepared by American Agricultural Services, Inc. and ENCAS Analytical Labs. 370 p. 

43378801 Premkumar, N.; Stewart, S. (1994) Uniformly (carbon 14)-Ring Labeled 2,4-

Dichlorophenoxyacetic Acid: A Metabolism Study in Bluegill Sunfish: Final

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43496101 Premkumar, N.; Vengurlekar, S. (1994) Uniformly (carbon 14)- Ring Labeled

2,4-Dichlorophenoxyacetic Acid 2-Ethylhexyl Ester: Nature of the Residue in

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43592101 Rosemond, J. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Rangelands Following Ground Applications

with 2,4-D 2-Ethylhexyl Ester: (Final Report): Lab Project Number: AA930220:

93-0025-0220. Unpublished study prepared by American Agricultural Services,

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43610801 Rosemond, J. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxyacetic Acid) in Rangelands Following Ground Applications

with 2,4-D Dimethylamine Salt: Lab Project Number: 93-0025-0219:

AA930219. Unpublished study prepared by American Agricultural Services and

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43610802 Rosemond, J. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxyacetic Acid) in Grass Pastures Following Ground Applications

with 2,4-D 2-Ethylhexyl Ester: Lab Project Number: AA930217: 93-0026-0217.

Unpublished study prepared by American Agricultural Services and EN-CAS

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43665201 Carringer, S. (1995) Magnitude of the Residue of 2,4-D (2,4-Dichlorophenoxy

Acetic Acid) in/on Wheat (Winter and Spring) Following Ground Applications

with 2,4-D 2-Ethylhexyl Ester: Lab Project Number: AA930204: 93-0019-1054:

47509. Unpublished study prepared by American Agricultural Services, Inc. and

En-Cas Analytical Labs. 705 p. 

43665202 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in/on Wheat (Winter and Spring) Following

Ground Applications with 2,4-D Acid: Lab Project Number: AA930205: 93-

0019-0205: ENC-2/93. Unpublished study prepared by American Agricultural

Services, Inc. and En-Cas Analytical Labs. 403 p. 

43665203 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Grass Pastures Following Ground

Applications with 2,4-D Dimethylamine Salt: Lab Project Number: AA930216:

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43665204 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Grass Pastures Following Ground

Applications with 2,4-D Acid: Lab Project Number: AA930218: 93-0026-0218:

ENC-2/93. Unpublished study prepared by American Agricultural Services, Inc.

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43665205 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Rangelands Following Ground Applications

with 2,4-D Acid: Lab Project Number: AA930221: 93-0025-0221: ENC-2/93.

Unpublished study prepared by American Agricultural Services, Inc. and EnCas Analytical Labs. 368 p. 

43669801 Carringer, R. (1994) Magnitude of the Residue of 2,4-D (2,4-Dichlorophenoxy

Acetic Acid) in Soybeans Following Ground Applications with 2,4-D

Ethylhexyl Ester: Amendment to Final Report: Lab Project Number:

AA930226: 60635: 60636. Unpublished study prepared by American

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43676801 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Field Corn Following Ground Applications

with 2,4-D-Ethlhexyl Ester: Lab Project Number: AA930209: ENC-2/93: 93-

0020-0209. Unpublished study prepared by American Agricultural Services and

EN-CAS Analytical Labs. 708 p. 

43676802 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Wheat (Winter and Spring) Following Ground

Applications with 2,4-D Dimethylamine Salt: Lab Project Number: AA930207:

93-0019-0207: ENC-2/93. Unpublished study prepared by American

Agricultural Services, Inc. and EN-CAS Analytical Labs. 569 p. 

43686001 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Field Corn Following Ground Applications

with 2,4-D Dimethylamine Salt: Lab Project Number: AA930208: 93-0020-

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EN-CAS Analytical Labs. 709 p. 

43691101 Zheng, S. (1995) Independent Laboratory Validation of EN-CAS Method No.

ENC-2/93, the Determination of 2,4-Dichlorophenoxy Acetic Acid (2,4-D)

in/on Various Raw Agricultural Commodities and Their Processed Fractions:

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Centre Analytical Labs, Inc. 95 p. 

43693701 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid, 2-Ethylhexyl

Ester in Processed Wheat (Winter and Spring) Fractions (Bran, Flour,

Middlings, and Shorts) Following Ground Applications with 2,4-D 2-Ethylhexyl

Ester: Lab Project Number: AA930206: 93-0019-0206. Unpublished study

prepared by American Agricultural Services, Inc.; Texas A&M Univ.; and ENCAS Analytical Labs. 700 p. 

43693702 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Field Corn Following Applications with 2,4-D

Acid: Lab Project Number: AA930210: 93-0020-0210. Unpublished study

prepared by American Agricultural Services, Inc. and EN-CAS Analytical Labs.

584 p. 
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43697801 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Grain Sorghum Following Ground

Applications with 2,4-D 2-Ethylhexyl Ester: Lab Project Number: AA930214:

93-0021-0214: F93196531. Unpublished study prepared by American

Agricultural Services, Inc. and EN-CAS Analytical Labs. 554 p. 

43709701 Carringer, S. (1995) Magnitude of the Residue of 2,4-D 2-Ethylhexyl Ester, 2,4-

D Acid in Processed Field Corn Fractions Following Ground Applications with

2,4-D 2-Ethylhexyl Ester: Lab Project Number: AA930211: 93-0020-0211:

ENC-2/93. Unpublished study prepared by American Agricultural Services, Inc.

and EN-CAS Analytical Labs. 658 p. 

43709702 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Processed Grain Sorghum Fractions (Starch

and Flour) Following Ground Applications with 2,4-D Dimethylamine Salt: Lab

Project Number: AA930213: 93-0021-0213: ENC-2/93. Unpublished study

prepared by American Agricultural Services, Inc. and EN-CAS Analytical Labs.

539 p. 

43718001

Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Grain Sorghum Following Ground

Applications with 2,4-D Dimethylamine Salt: Lab Project Number: AA930212:

93-0021-0212. Unpublished study prepared by American Agricultural Services,

Inc. and EN-CAS Analytical Labs. 567 p.

43718002 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Grain Sorghum Following Ground

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Unpublished study prepared by American Agricultural Services, Inc. and ENCAS Analytical Labs. 518 p.

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Dichlorophenoxy Acetic Acid) in Sugarcane Following Ground Application

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43747901 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

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43755402 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid (2,4-

Dichlorophenoxy Acetic Acid) in Processed Rice Fractions (Hulls, Bran, and

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43779501 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid in Grass Pastures

Following Ground Applications with 2,4-D 2-Ethylhexyl Ester: (Final Report):

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43779502 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid in Grass Pastures

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43779503 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid in Rangelands

Following Ground Applications with 2,4-D 2-Ethylhexyl Ester: (Final Report):

Lab Project Numbers: AA940505: 6397-156. Unpublished study prepared by

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43779504 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid in Rangelands

Following Ground Applications with 2,4-D Dimethylamine Salt: (Final Report):

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360 p. 

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Dichlorophenoxy Acetic Acid) in Rice Following Ground Application with 2,4-

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EN-CAS Analytical Labs. 582 p.

43797901 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid in Wheat (Winter

and Spring) Following Ground Applications with 2,4-D 2-Ethylhexyl Ester:

(Final Report): Lab Project Number: AA940501: HWI 6397-151. Unpublished

study prepared by American Agricultural Services, Inc. and Hazleton

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43797903 Carringer, S. (1995) Magnitude of the Residue of 2,4-D Acid in Wheat (Winter

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(Final Report): Lab Project Number: AA940502: HWI 6397-152. Unpublished

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Wisconsin, Inc. 607 p. 

43809901 Barker, W. (1995) Determination of Frozen Storage Stability for 2,4-

Dichlorophenoxy Acetic Acid (2,4-D) in/on Crops: Final Report: Lab Project

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43853601 Kunkel, D. (1995) 2,4-D: Magnitude of Residue on Wild Rice (Zizania palustris

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43870301 Johnson, G.; Strickland, M. (1995) Storage Stability of (2,4-

Dichlorophenoxy)Acetic Acid Residues in/on Raw Orange, Grapefruit, Lemon

Fruit and Processed Lemon Products: Final Report: Lab Project Number: 101-

006: R289408: CCQC 94-03. Unpublished study prepared by Western

EcoSystems Technology; Research for Hire; and Corning Hazleton. 205 p. 

43870302 Johnson, G.; Strickland, M. (1995) Magnitude of Residues in/on Products

Processed from Lemons Treated with (2,4-Dichlorophenoxy)Acetic Acid

Isopropyl Ester: Final Report: Lab Project Number: 101-005: R289407:

R289409. Unpublished study prepared by Western EcoSystems Technology;

Research for Hire; and Corning Hazleton. 267 p. 

43870303 Johnson, G.; Strickland, M. (1995) Magnitude of Residues in/on California

Citrus Fruit after Growth Regulator Treatments with (2,4-

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EcoSystems Technology; Research for Hire; and Corning Hazleton. 337 p. 

43879901 Barney, W.; Kunkel, D. (1995) 2,4-D: Magnitude of the Residue on Peach: Lab

Project Number: 4255.93-CAR05: 4255.93-GA08: 4255.93-NJ01. Unpublished

study prepared by Environmental Technologies Institute, Inc. and Interregional

Research Project No. 4. 282 p. 

43879902 Barney, W.; Kunkel, D. (1995) 2,4-D: Magnitude of the Residue on Cherry: Lab

Project Number: 4254.92-NDR03: 4254.94-CA49: 4254.92-MI10.

Unpublished study prepared by Environmental Technologies Institute, Inc. and

Interregional Research Project No. 4. 264 p. 

43879903 Barney, W.; Kunkel, D. (1995) 2,4-D: Magnitude of the Residue on Plum: Lab

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43879904 Barney, W.; Kunkel, D. (1995) 2,4-D: Magnitude of the Residue on Pistachios:

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Interregional Research Project No. 4. 215 p. 

43879905 Kunkel, D. (1995) 2,4-D: Magnitude of Residue on Asparagus: Lab Project

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43886401 Barney, W.; Kunkel, D. (1995) 2,4-D: Magnitude of the Residue on Potato

(Reregistration): Lab Project Number: 04302: .92-ND04: .92-CA24.

Unpublished study prepared by University of Idaho; University of Maine; and

University of Wisconsin. 783 p. 

43886402 Barney, W.; Kunkel, D. (1995) 2,4-D: Magnitude of Residue on Cranberry

(Reregistration): Lab Project Number: 4297.92-NDR08: 4297.92-MA01:

4297.92-WI07. Unpublished study prepared by University of Massachusetts and

University of Wisconsin. 303 p. 

43886403 Kunkel, D. (1995) 2,4-D: Magnitude of Residue on Blueberry (Lowbush): Lab

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43886404 Kunkel, D. (1995) 2,4-D: Magnitude of Residue on Strawberry (Reregistration):

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43886405 Kunkel, D. (1995) 2,4-D: Magnitude of Residue on Pear (Reregistration): Lab

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43886406 Kunkel, D. (1995) 2,4-D: Magnitude of Residue on Corn (Sweet): Lab Project

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43893701 Siirila, A. (1995) Method Validation for the Determination of (2,4-

Dichlorophenoxy)Acetic Acid in/on California Citrus Fruit and Lemon

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Hazleton Wisconsin, Inc. 149 p. 

43943101 Barney, W.; Kunkel, D. (1995) 2,4-D: Magnitude of the Residue on Apple: Lab

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43947901 Kunkel, D. (1996) 2,4-D: Magnitude of the Residue on Grape: Lab Project

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43963801 Kunkel, D. (1996) 2,4-D: Magnitude of the Residue on Filberts (Reregistration):

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43963802 Kunkel, D. (1996) 2,4-D: Magnitude of the Residue on Pecan (Reregistration):

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44016501 Howard, J. (1996) Development, Validation and Radiovalidation of Analytical

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44016502 Howard, J. (1996) Development and Validation of Analytical Methodology for

the Quantitation of Residues of 2,4-Dichlorophenoxyacetic Acid (2,4-D) in Beef

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44024801 Krautter, G.; Downs, J. (1996) 2,4-D: Magnitude of Residues in Meat and Milk

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44135201 Biever, R. (1996) A Freshwater Fish and Shellfish Magnitude of Residues Study

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44190301 Carringer, S. (1996) Magnitude of the Residue of 2,4-D Acid in Wheat (Winter

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44211901 Kunkel, D. (1997) 2,4-D: Magnitude of the Residue on Almond: (Draft Report):

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44268501 Kunkel, D. (1997) 2,4-D: Magnitude of the Residue on Blueberry (High Bush):

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Moore, R. (1990) 2,4-Dichlorophenoxyacetic acid, butoxyethyl ester: Aqueous

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Bulk Density, Solubility, Vapor Pressure, Dissociation Constant, Octanol/Water

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44620501 Hamilton, T. (1998) Group A: Product Identity and Composition of TIPA-4

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41478302 Gollapudi, B.; Samson, Y.; McClintock, M. (1990) Evaluation of a Formulation

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41797901 Samson, Y.; Gollapudi, B. (1990) Response to the Comments by the U. S. EPA

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Ames Salmonella/Mammalian-Microsome Bacte- rial Mutagenicity Assay: Lab

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41797902 Samson, Y.; Gollapudi, B. (1990) Response to the Comments by the U. S. EPA

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41797903 Samson, Y.; Gollapudi, B. (1990) Response to the Comments by the U. S. EPA

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41870101 Ivett, J. (1990) Mutagenicity Test on 2,4-Dichlorophenoxyacetic Acid in vivo

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41870102 Ivett, J. (1990) Mutagenicity Test on 2,4-Dimethylamine Salt in vivo Mouse

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41870103 Ivett, J. (1990) Mutagenicity Test on 2,4-D-2-Ethylhexyl Ester in vivo Mouse

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41896701 Schulze, G. (1991) Subchronic Toxicity Study in Rats with 2,4-Dichlorophenoxyacetate Acid-2-Ethylhexyl Ester: Final Report: Lab Project

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41896702 Schulze, G. (1991) Subchronic Toxicity Study in Rats with the Di- methylamine

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481 p. 

41920901 Shults, S.; Brock, A.; Killeen, J. (1990) Acute Oral Toxicity (LD50) Study in

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41920902 Shults, S.; Brock,A.; Killeen, J. (1990) Primary Eye Irritation Study in Albino

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41920903 Shults, S.; Brock, A.; Killeen, J. (1990) Primary Dermal Irritation Study in

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41920904 Shults, S.; Brock, A.; Killeen, J. (1990) Dermal Sensitization Study (Closed

Patch Repeated Insult) in Guinea Pigs with Di- ethanolamine Salt of 2,4-D: Lab

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41920905 Siglin, J. (1991) 21-DAy Dermal Toxicity Study in Rabbits with Diethanolamine Salt of 2,4-D DEA: Final Report: Lab Project Num- ber: 3229.1.

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41920909 McKeon, M. (1990) Mutagenicity Test on Diethanolamine Salt of 2,4-D in the

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41920910 Lawlor, T.; Holloway, P. (1990) Mutagenicity Test on Diethanolamine Salt of

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41920911 Shults, S.; Brock, A.; Killeen, J. (1991) Acute Dermal Toxicity Study in Albino

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41928101 Szabo, J.; Rachunek, B. (1991) 2,4-D, Butoxyethyl Ester: 13-Week Dietary

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41986601 Jackson, G.; Hardy, C. (1991) Diethanolamine Salt of 2,4-D: Acute Inhalation

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41986602 Siglin, J. (1991) Range-Finding Teratology Study in Rats with Diethanolamine

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41994001 Serrone, D.; Killeen, J.; Benz, G. (1991) A Subchronic Toxicity Study in Rats

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798 p. 

42013501 Rodwell, D. (1991) Range Finding Teratology Study in Rabbits with

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42015701 Gollapudi, B. (1991) Response to Comments by U.S. EPA: Evaluation of 2,4-D

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42015702 Gollapudi, B. (1991) Response to Comments by U. S. EPA: Evaluation of 2,4-

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Mouse Bone Marrow Micronuleus Test: Lab Project Number: TXT:K-008866-

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42015703 Gollapudi, B. (1991) Response to Comments by U. S. EPA: Evaluation of 2,4-

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42015704 Gollapudi, B. (1991) Response to Comments by U. S. EPA: Evaluation of 2,4-

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42015705 Gollapudi, B. (1991) Response to Comments by U. S. EPA: Evaluation of 2,4-

Dichlorophenoxyacetic Acid Triisopropanolamine Salt (2,4- D TIPA) in the

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42015706 Gollapudi, B. (1991) Response to Comments by U.S. EPA: Evaluation of 2,4-

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42021401 Yano, B.; Cosse, P.; Corley, R. (1991) 2,4-D Isopropylamine Salt (2,4-D IPA):

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42021402 Yano, B.; Cosse, P.; Markham, D. (1991) 2,4-D Triisopropylamine Salt (2,4-D

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42055501 Rodwell, D. (1991) Teratology Study in Rabbits with Diethanolamine Salt of

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42158701 Liberacki, A.; Breslin, W.; Yano, B. (1991) Triisopropanolam- ine Salt of 2,4-D:

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42158702 Liberacki, A.; Breslin, W.; Yano, B. (1991) Isopropylamine Salt of 2,4-D: Oral

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42158704 Breslin, W.; Liberacki, A.; Yano, B. (1991) Isopropylamine Salt of 2,4-D: Oral

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42158706 Zablotny, C.; Yano, B.; Breslin, W. (1991) 2,4-D 2-Butoxyethyl Ester: Oral

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42220301 Dryzga, M.; Bormett, G.; Nolan, R. (1992) 2,4-Dichlorophenoxyacetate,

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42224001 Martin, T. (1991) Developmental Toxicity (Embryo-Fetal Toxicity and

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Administered Orally via Stomach Tube to New Zealand White Rabbits: Lab

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42304601 Martin, T. (1992) Developmental Toxicity (Embryo-Fetal Toxicity and

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42304602 Martin, T. (1992) Dosage-Range Developmental Toxicity (Embryo-Fetal

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Isooctyl Ester) Administered Orally Via Gavage to Crl:CD BR VAF/Plus

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42579701 Dryzga, M.; Bormett, G.; Stewart, H.; et al. (1992) 2,4-Dichlorophenoxyacetate,

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42605202 Cieszlak, F. (1992) 2,4-Dichlorophenoxyacetic Acid, 2-Ethylhexyl Ester: Acute

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42780001 Dalgard, D. (1993) 13-Week Dietary Toxicity Study of 2,4-D in Dogs: Final

Report: Lab Project Number: HWA 2184-125. Unpublished study prepared by

Hazleton Washington, Inc. 302 p. 

42780002 Dalgard, D. (1993) 13-Week Dietary Toxicity Study with the Dimethylamine

Salt of 2,4-D in Dogs: Final Report: Lab Project Number: HWA 2184-126.

Unpublished study prepared by Hazleton Washington, Inc. 267 p. 

42780003 Dalgard, D. (1993) 13-Week Dietary Toxicity Study with the 2-Ethylhexyl Ester

of 2,4-D in Dogs: Final Report: Lab Project Number: HWA 2184-127.

Unpublished study prepared by Hazleton Washington, Inc. 271 p. 

42780004 Dalgard, D. (1992) 4-Week Exploratory Rangefinding Study in Dogs with 2,4-

D: Final Report: Lab Project Number: HWA 2184-121. Unpublished study

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42780005 Dalgard, D. (1992) 4-Week Exploratory Rangefinding Study in Dogs with 2-

Ethylhexyl Ester of 2,4-D: Final Report: Lab Project Number: HWA 2184-122.

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42780006 Dalgard, D. (1992) 4-Week Exploratory Rangefinding Study in Dogs with the

Dimethylamine Salt of 2,4-D: Final Report: Lab Project Number: HWA 2184-

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42865301 Dryzga, M.; Freshour, N.; Nolan, R. (1993) 2,4-Dichlorophenoxy- acetate,

Isopropylamine Salt: Dissociation and Metabolism in Male Fischer 344 Rats:

Lab Project Number: M-004725-014. Unpub- lished study prepared by The

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43049001 Dalgard, D. (1993) 52-Week Dietary Toxicity Study with 2,4-D in Dogs: Final

Report: Lab Project Number: HWA 2184-124: 2184124. Unpublished study

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43115201 Mattsson, J.; McGuirk, R.; Yano, B. (1994) 2,4-Dichlorophenoxyacetic Acid

(2,4-D): Acute Neurotoxicity Study in Fischer 344 Rats: Lab Project Number:

K-002372-066. Unpublished study prepared by The Dow Chemical Co. 451 p. 

43327301 Linscombe, V.; Lick, S. (1994) Evaluation of 2,4-D Triisopropanolamine Salt in

an In vitro Chromosomal Aberration Assay Utilizing Rat Lymphocytes:

Amended Final Report: Lab Project Number: K-008866-017: 10233.

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43327302 Linscombe, V.; Lick, S. (1994) Evaluation of 2,4-D Triisopropanolamine Salt in

the Chinese Hamster Ovary Cell/Hypoxanthine-Guanine-Phosphoribosyl

Transferase (CHO/HGPRT) Forward Mutation Assay: Amended Final Report:

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43327303 Linscombe, V.; Lick, S. (1994) Evaluation of 2,4-Dichlorophenoxyacetic Acid

Isopropylamine Salt in an In vitro Chromosomal Aberration Assay Utilizing Rat

Lymphocytes: Lab Project Number: M-004725-016: 10233. Unpublished study

prepared by Dow Chemical Co. 45 p. 

43327304 Linscombe, V.; Lick, S. (1994) Evaluation of 2,4-Dichlorophenoxyacetic Acid

Isopropylamine Salt in the Chinese Hamster Ovary Cell/HypoxanthineGuanine-Phosphoribosyl Transferase (CHO/HGPRT) Forward Mutation Assay:

Lab Project Number: M-004725-017: 10233. Unpublished study prepared by

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43327305 Linscombe, V.; Lick, S. (1994) Evaluation of the 2,4-Dichlorophenoxyacetic

Acid Butoxyethyl Ester in an In vitro Chromosomal Aberration Assay Utilizing

Rat Lymphocytes: Lab Project Number: K-007722-022: 10233. Unpublished

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43394201 Linscombe, V.; Lick, S. (1994) Evaluation of 2,4-Dichlorophenoxyacetic Acid

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43515501 Tompkins, E. (1994) A 90-Day Oral (Capsule) Toxicity Study of 2,4-D

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43515901 Tompkins, E. (1995) A 90-Day Dietary Subchronic Toxicity Study of 2,4-D

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43523001 Nemec, M. (1994) A Dose Range-finding Developmental Toxicity Study of 2,4-

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43523101 Nemec, M. (1995) A Developmental Toxicity Study of 2,4-D Isopropyl Ester in

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43597201 Stott, W.; Johnson, K.; Gilbert, K.; et al. (1995) 2,4-Dichlorophenoxyacetic

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43612001 Jeffries, T.; Yano, B.; Ormand, J. et al. (1995) 2,4-Dichlorophenoxyacetic Acid:

Chronic Toxicity/Oncogenicity Study in Fischer 344 Rats: Final Report: Lab

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43879801

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Report: Lab Project Number: K-002372-063M: 33475: 913. Unpublished study

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43930501 Ham, A. (1996) Genotoxicity Test on Isopropyl Ester of 2,4-DichloroPhenoxyacetic Acid in the Assay for Unscheduled DNA Synthesis in Rat Liver

Primary Cell Cultures: Lab Project Number: 16692-0-447: 2731-100: 615.

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43930801 Murli, H. (1996) Mutagenicity Test on Isopropyl Ester of 2,4-Dichloro Phenoxy

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43935101 Lawlor, T. (1996) Mutagenicity Test on Isopropyl Ester of 2,4-Dichlorophenoxy

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Histopathology--Brains from Low- and Mid-Dose Level Rats Sacrificed for the

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44725303 Cieszlak, F.; Brooks, K. (1998) Esteron 6E: Acute Primary Eye Irritation Study

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45761210 Gollapudi, B.; Charles, J.; Linscombe, V.; et al. (1999) Evaluation of the

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44972201 Klonne, D. (1999) Integrated Report for Evaluation of Potential Exposures to

Homeowners and Professional Lawn Care Operators Mixing, Loading, and

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44655701 Wilson, R. (1998) Comparison of Transferable Turf Residues from the

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44655704 Hughes, D.; Read, S. (1998) Validation of a Method for the Determination of

2,4-D 2-EHE (2,4-dichlorophenoxyacetic acid 2-ethylhexyl ester); 2,4-DP 2-

EHE ?2-(2,4-dichlorophenoxy) propionic acid 2-ethylhexyl ester|; MCPA 2-

EHE (4-chloro-2-methylphenoxyacetic acid 2-ethylhexyl ester); 2,4-D (2,4-

dichlorophenoxyacetic acid), MCPP ?(RS)-2-(4-chloro-methylphenoxy)

propionic acid|, and Dicamba (3,6-dichloro-2-methoxybenzoic acid)(In

Combination); and MCPA (4-chloro-2-methylphenoxyacetic acid), MCPP

?(RS)-2-(4-chloro-2-methylphenoxy) propionic acid|, and 2,4-DP ?(RS)-2-(2,4-

dichlorophenoxy) propionic acid| (In Combination on Percale Cloth: Lab Project

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International Ltd. 68 p. 

41835211 Ward, T.; Boeri, R. (1991) Chronic Toxicity of 2,4-D to the Daphnid Daphnia

magna: Lab Project Number: 9040-D. Unpublished study prepared by Resource

Analysts, Inc./EnviroSystems Div. 38 p.

42018303 Holmes, C.; Peters, G. (1991) Diethanolamine Salt 2,4-D: A Flow- through

Life-Cycle Toxicity Test with the Cladoceran (Daphnia magna): Final Report:

Lab Project Number: 281A/106. Unpublished study prepared by Wildlife

International Ltd. 51 p. 
2,4-D Bibliography

Page 284 of 304

41835210 Ward, G. (1991) 2,4-D, Dimethylamine Salt: Chronic Toxicity to the Water

Flea, Daphnia magna, Under Flow-through Test Conditions: Lab Project

Number: J9002003D. Unpublished study prepared by Toxikon Environmental

Sciences. 45 p.

41353802 Gersich, F.; Gorzinski, S.; Harms, D.; et al. (1989) 2,4-Dichloro- phenoxy

Acetic Acid (2-Butoxyethyl Ester): Evaluation of the Chronic Toxicity to

Daphnia magna Straus: Final Report: Project No. ES-DR-0131-3037-2.

Unpublished study prepared by The Dow Chemical Co. 36 p. 

42979701 Ward, T.; Magazu, J.; Boeri, R. (1993) 2,4-D: Acute Flow-Through Mollusc

Shell Deposition Test: Lab Project Number: 286-DE. Unpublished study

prepared by T.R. Wilbury Labs, Inc. 38 p.

41737306 Vaishnav, D.; Yurk, J.; Wade, B. (1990) 2,4-Dichlorophenoxyacetic Acid:

Acute Toxicity to Pink Shrimp (Penaeus Duorarum) Under Flow-through

Conditions: Lab Project Number: 3903008000-0200- 3140. Unpublished study

prepared by Environmental Science and Engineering Inc. 37 p. 

42018302 Graves, W.; Peters, G. (1991) Diethanolamine Salt of 2,4-D: A 96- Hour Shell

Deposition Test with the Eastern Oyster (Crassostrea virginica): Lab Project

Number: 281A/115. Unpublished study prepared by Wildlife International Ltd.

39 p. 

41975107 Graves, W.; Peters, G. (1991) Diethanolamine Salt of 2,4-D: A 96- Hour FlowThrough Acute Toxicity Test With the Pink Shrimp (Pen- aeus Duorarum):

Final Report: Lab Project Number: 281A-104A. Unpublished study prepared by

Wildlife International. 37 p. 

41158310 Heitmuller, T. (1975) Acute Toxicity of DMA-4 to Larvae of the Eastern Oyster

(Crassostrea virginica), Pink Shrimp (Penaeus duorarum), and Fiddler Crabs

(UCA pugilator): Project Study ID: GH-RC-10. Unpublished study prepared by

Bionomics--EG&G, Inc. 12 p. 

41973401 Ward, G. (1991) 2,4-D, Dimethylamine Salt: Acute Effect on New Shell Growth

of, the Eastern Oyster, Crassostrea virginica, Under Floow-through Conditions:

Lab Project Number: J9002003C. Unpublished study prepared by Toxikon

Environmental Sciences. 41 p. 

41429003 Dionne, E. (1990) Acute Toxicity to Eastern Oyster (Crassostrea virginica)

under Flow-through Conditions: (2,4-D IPA): Lab Proj- ject Number: 89-11-

3134: 236.0689.6101.504: ES-2227. Unpublish- ed study prepared by

Springborn Laboratories, Inc. 39 p.

41429002 Sousa, J. (1990) Acute Toxicity to Pink Shrimp (Penaeus duorarum) Under

Flow-through Conditions: (2,4-D IPA): Lab Project Number: 89-11-3154: 236.

0689. 6101. 516: ES-2229. Unpublished study prepared by Springborn

Laboratories, Inc. 40 p. 
2,4-D Bibliography

Page 285 of 304

41429006 Dionne, E. (1990) Acute Toxicity to Eastern Oyster (Crassostrea virginica)

under Flow-through Conditions: (2,4-D TIPA): Lab Pro- ject Number: 89-9-

3092: 236.0689.6100.504: ES-2226. Unpublished study prepared by Springborn

Laboratories, Inc. 37 p. 

41429005 Sousa, J. (1990) Acute Toxicity to Pink Shrimp (Penaeus duorarum) Under

Flow-through Conditions: (2,4-D TIPA): Lab Project Number: 89-12-3169:

236.0689.6100.516: ES-2228. Unpublished study pre- pared by Springborn

Laboratories, Inc. 37 p. 

41835204 Ward, T.; Boeri, R. (1991) Acute Flow-through Mollusc Shell Deposi- tion Test

with 2,4-D, 2-Ethylhexyl Ester: Lab Project Number: 9034-D. Unpublished

study prepared by Resource Analysts, Inc./ EnviroSystems Div. 25 p. 

41835201 Ward, T.; Boeri, R. (1991) Acute Flow-through Mollusc shell Deposi- tion Test

with Esteron 99 Herbicide: Lab Project Number: 9037-D. Unpublished study

prepared by Resource Analysts, Inc./Enviro- Systems Div. 25 p. 

41835206 Ward, T.; Boeri, R. (1991) Acute Flow-through Toxicity of 2,4-D, 2- Ehtylhexyl

Ester to the Grass Shrimp, Palaemonetes pugio: Lab Project Number: 9036-D.

Unpublished study prepared by Resource Analysts, Inc. 25 p. 

41835203 Ward, T.; Boeri, R. (1991) Acute Flow-through Toxicity of Esteron 99

Herbicide to the Grass Shrimp, Palaemonetes pugio: Lab Pro- ject Number:

9039-D. Unpublished study prepared by Resource Analysts, Inc./EnviroSystems

Div. 25 p.

41420001 Hughes, J. (1989) The Toxicity of 2,4-D to Selenastrum capricorn- utum: Lab

Project Number: 0460-05-1100-1. Unpublished study prepared by Malcolm

Pirnie, Inc. 33 p. 

43307901 Hughes, J.; Williams, T.; Conder, L. (1994) The Toxicity of 2,4-D to Anabaena

flos-aquae: Lab Project Number: 10/01/1. Unpublished study prepared by

Carolina Ecotox, Inc. 57 p. 

43307902 Hughes, J.; Williams, T.; Conder, L. (1994) The Toxicity of 2,4-D to Navicula

pelliculosa: Lab Project Number: 10/01/2. Unpublished study prepared by

Carolina Ecotox, Inc. 55 p. 

43307903 Hughes, J.; Williams, T.; Conder, L. (1994) The Toxicity of 2,4-D to

Skeletonema costatum: Lab Project Number: 10/01/3. Unpublished study

prepared by Carolina Ecotox, Inc. 57 p. 

43768001 Hughes, J.; Williams, T.; Alexander, M. (1995) The Toxicity of Isopropyl Ester

of 2,4-Dichlorophenoxyacetic Acid to Selenastrum capricornutum: Lab Project

Number: 17-01-1. Unpublished study prepared by Carolina Ecotox, Inc. 56 p. 
2,4-D Bibliography

Page 286 of 304

44295101 Hughes, J.; Williams, T.; Conder, L. (1997) Effect of 2,4-

Dichlorophenoxyacetic Acid on the Growth and Reproduction of Lemna gibba

G3: (Final Report): Lab Project Number: 10-05-1. Unpublished study prepared

by Carolina Ecotox, Inc. 72 p. 

42712204 Thompson, S.; Swigert, J. (1993) Diethanolamine Salt of 2,4-D: A 14-Day

Toxicity Test with Duckweed (Lemna gibba G3): Final Report: Lab Project

Number: 281A-116. Unpublished study prepared by Wildlife International, Ltd.

45 p. 

42712205 Thompson, S.; Swigert, J. (1993) Diethanolamine Salt of 2,4-D: A 5-Day

Toxicity Test with the Freshwater Alga (Selenastrum capricornutum): Final

Report: Lab Project Number: 281A-117A. Unpublished study prepared by

Wildlife International, Ltd. 39 p. 

42712201 Thompson, S.; Swigert, J. (1993) Diethanolamine Salt of 2,4-D: A 5-Day

Toxicity Test with the Marine Diatom (Skeletonema costatum): Final Report:

Lab Project Number: 281A-119. Unpublished study prepared by Wildlife

International, Ltd. 38 p. 

42712202 Thompson, S.; Swigert, J. (1993) Diethanolamine Salt of 2,4-D: A 5-Day

Toxicity Test with the Freshwater Diatom (Navicula pelliculosa): Final Report:

Lab Project Number: 281A-120. Unpublished study prepared by Wildlife

International, Ltd. 39 p. 

42712203 Thompson, S.; Swigert, J. (1993) Diethanolamine Salt of 2,4-D: A 5-Day

Toxicity Test with the Freshwater Alga (Anabaena flos-aquae): Final Report:

Lab Project Number: 281A-118. Unpublished study prepared by Wildlife

International, Ltd. 39 p. 

41505904 Hughes, J. (1989) The Toxicity of 2,4-D, Dimethylamine Salt to Lemna gibba:

Lab Project Number: 0460-05-1100-7. Unpublished prepared by Malcolm

Pirnie, Inc. 33 p. 

41420002 Hughes, J. (1989) The Toxicity of 2,4-D, Dimethylamine Salt to Selenastrum

capricornutum: Lab Project Number: 0460-05-1100-3. Unpublished study

prepared by Malcolm Pirnie, Inc. 33 p. 

41505901 Hughes, J. (1990) The Toxicity of 2,4-D, Dimethylamine Salt to Skeletonema

costatum: Lab Project Number: 0460-05-1100-6. Un- published study prepared

by Malcolm Pirnie, Inc. 34 p. 

41505903 Hughes, J. (1990) The Toxicity of 2,4-D, Dimethylamine Salt to Navicula

pelliculosa: Lab Project Number: 0460-05-1100-5. Unpub- lished study

prepared by Malcolm Pirnie, Inc. 32 p. 

41505902 Hughes, J. (1989) The Toxicity of 2,4-D, Dimethtylamine Salt to Anabaena flosaquae: Lab Project Number: 0460-05-1100-4. Unpub- lished study prepared by

Malcolm Pirnie, Inc. 33 p. 
2,4-D Bibliography

Page 287 of 304

41732102 Hughes, J. (1990) The Toxicity of 2,4-D, Isopropylamine Salt to Selenastrum

capricornutum: Lab Project Number: B460-10-1. Un- published study prepared

by Malcolm Pirnie, Inc. 34 p. 

43488602 Hughes, J.; Williams, T.; Conder, L. (1994) The Toxicity of 2,4-D TIPA to

Lemna gibba: Lab Project Number: 10-02-4: ES-2838. Unpublished study

prepared by Carolina Ecotox, Inc. 66 p. 

41732101 Hughes, J. (1990) The Toxicity of 2,4-D, Triisopropanolamine Salt to

Selenastrum capricornutum: Lab Project Number: B460-09-1. Unpublished

study prepared by Malcolm Pirnie, Inc. 34 p. 

43488603 Hughes, J.; Williams, T.; Conder, L. (1994) The Toxicity of 2,4-D TIPA to

Skeletonema costatum: Lab Project Number: 10-02-3: ES-2837. Unpublished

study prepared by Carolina Ecotox, Inc. 65 p. 

43488601 Hughes, J.; Williams, T.; Conder, L. (1994) The Toxicity of 2,4-D TIPA to

Navicula pelliculosa: Lab Project Number: 10-02-2: ES-2836. Unpublished

study prepared by Carolina Ecotox, Inc. 66 p. 

43488604 Hughes, J.; Williams, T.; Conder, L. (1994) The Toxicity of 2,4-D TIPA to

Anabaena flos-aquae: Lab Project Number: 10-02-1: ES-2807. Unpublished

study prepared by Carolina Ecotox, Inc. 64 p.

43188201 Selim, S. (1994) Hydrolysis of Pyrethrin 1 as a Function of pH at 25 degrees C:

Lab Project Number: P1092011: 93-1147.BTC. Unpublished study prepared by

Biological Test Center. 83 p. 

42068403 Hughes, J. (1990) The Toxicity of 2,4-D, Butoxyethyl Ester to Navi- cula

pelliculosa: Lab Project Number: B460-08-2. Unpublished study prepared by

Malcolm Pirnie, Inc. 35 p. 

41735203 Hughes, J. (1990) The Toxicity of 2,4-D,2-Ethylhexyl Ester to Lemna gibba:

Lab Project Number: B460-07-4. Unpublished study pre- pared by Malcolm

Pirnie, Inc. 36 p. 

41735206 Hughes, J. (1990) The Toxicity of 2,4-D,2-Ethylhexyl Ester to Sele- nastrum

capricornutum: Lab Project Number: 0460-05-1100-2. Un- published study

prepared by Malcolm Pirnie, Inc. 38 p. 

41735204 Hughes, J. (1990) The Toxicity of 2,4-D,2-Ethylhexyl to Skeletonema costatum:

Lab Project Number: B460-07-3. Unpublished study pre- pared by Malcolm

Pirnie, Inc. 38 p. 

41735205 Hughes, J. (1990) The Toxicity of 2,4-D,2-Ethylhexyl Ester to Navi- cula

pelliculosa: Lab Project Number: B460-07-2. Unpublished study prepared by

Malcolm Pirnie, Inc. 38 p. 
2,4-D Bibliography

Page 288 of 304

41735202 Hughes, J. (1990) The Toxicity of 2,4-D,2-Ethylhexyl Ester to Ana- baena flosaquae: Lab Project Number: B460-07-1. Unpublished study prepared by

Malcolm Pirnie, Inc. 37 p. 

0016000 Shell Chemical Company (1975) Data Supporting the Use of Nudrin 1.8

Insecticide Solution for the Control of Insect Pests on Squash. Summary of

studies 232410-T through 232410-V. (Unpublished study received Jun 29, 1976

under 201-347; CDL:232410-B) 

41975101 Campbell, S.; Grimes, J.; Smith, G. (1991) Diethanolamine Salt of 2,4-D: An

Acute Toxicity Study with the Northern Bobwhite: Lab Project Number: 281-

109. Unpublished study prepared by Wildlife International. 29 p.

41546201 Hoxter, K.; Culotta, J.; Jaber, M. (1990) An Acute Oral Toxicity Study with the

Northern Bobwhite: Final Report: Lab Project Num- ber: 103-310. Unpublished

study prepared by Wildlife Inter- national Ltd. 21 p. 

00138871 Beavers, J.; Jaber, M.; Joiner, G.; et al. (1983) An Acute Oral Toxicity Study in

the Mallard with 2,4-D Isopropylamine Salt: Project No. 103-226. Final rept.

(Unpublished study received Jan 18, 1984 under 464-596; prepared by Wildlife

International Ltd., submitted by Dow Chemical U.S.A., Midland, MI; CDL:

252291-F) 

41644401 Culotta, J.; Campbell, S.; Hoxter, K. et al. (1990) 2,4-Dichloro- phenoxyacetic

Acid, Triisopropanolamine Salt: An Acute Oral Toxicity Study with the

Northern Bobwhite: Lab Project Number: 103/329. Unpublished study prepared

by Wildlife International Ltd. 19 p. 

41454101 Lloyd, D.; Grimes, J.; Hoxter, K. (1990) 2, 4-Dichlorophenoxy- acetic Acid,

Butoxyethyl Ester: An Acute Oral Toxicity Study with the Northern Bobwhite:

Final Report: Lab Project Number: 103-318. Unpublished study prepared by

Wildlife International Ltd. 20 p. 

41158303 Beavers, J. (1984) (2,4-Dichlorophenoxy) Acetic Acid Isooctyl Ester: An Acute

Oral Toxicity Study with the Mallard: Project Study ID: 103-229. Unpublished

study prepared by Wildlife International Ltd. 20 p.

72472 Gleich, J.; Wei?ss|e, G.; Unkelbach, H.D.; et al. (1981) Teratogen- icity Study in

Himalayan Rabbits after Oral Administration: Experiment No. T 9127.

(Translation; unpublished study re- ceived Mar 31, 1981 under 21137-4;

prepared by E. Merck, W. Germany, submitted by EM Laboratories, Inc.,

Elmsford, N.Y.; CDL:244977-A) 

43935001 Palmer, S.; Beavers, J. (1996) 2,4-D Isopropyl Ester: An Acute Oral Toxicity

Study with the Northern Bobwhite: Lab Project Number: 435-103:

435/100295/QLD.NC/CHP105. Unpublished study prepared by Wildlife

International Ltd. 50 p.
2,4-D Bibliography

Page 289 of 304

41586101 Culotta, J.; Hoxter, K.; Foster, J.; et al. (1990) 2,4-D (2,4-Dich- loroxyacetic

Acid): A Dietary LC50 Study with the Northern Bob- white. Lab Project

Number: 103-306. Unpublished study prepared by Wildlife International Ltd. 55

p.

41546202 Culotta, J.; Foster, J.; Grimes, J. et al. (1990) A Dietary LC50 Study with the

Mallard: Lab Project Number: 103-307. Unpub- lished study prepared by

Wildlife International Ltd. 42 p. 

41975102 Hoxter, K.; Grimes, J.; Smith, G. ; et al. (1991) Diethanolamine Salt of 2,4-D: A

Dietary LC50 Study with the Northhern Bobwhite: Lab Project Number: 281-

107. Unpublished study prepared by Wil- dlife International. 32 p. 

41975103 Hoxter, K.; Grimes, J.; Smith, G.; et al. (1991) Diethanolamine Salt of 2,4-D: A

Dietary LC50 Study with the Northern Bobwhite: Lab Project Number: 281-

108. Unpublished study prepared by Wil- dlife International. 32 p. 

41749501 Long, R.; Foster, J.; Hoxter, K.; et al. (1990) 2,4-D Dimethylamine Salt: A

Dietary LC50 Study with the Northern Bobwhite: Lab Pro- ject Number: 103-

308. Unpublished study prepared by Wildlife International Ltd. 42 p. 

41749502 Long, R.; Foster, J.; Hoxter, K.; et al. (1990) 2,4-D Dimethylamine Salt: A

Dietary LC50 Study with the Northern Bobwhite: Lab Pro- ject Number: 103-

309. Unpublished study prepared by Wildlife International Ltd. 42 p. 

00138870 Beavers, J.; Jaber, M.; Joiner, G.; et al. (1983) A Dietary LC50 in the Bobwhite

with 2,4-D Isopropylamine Salt: Project No. 103- 224. Final rept. (Unpublished

study received Jan 18, 1984 un- der 464-596; prepared by Wildlife International

Ltd., submitted by Dow Chemical U.S.A., Midland, MI; CDL:252291-E) 

00138872 Beavers, J.; Jaber, M.; Joiner, G.; et al. (1983) A Dietary LC50 in the Mallard

with 2,4-D Isopropylamine Salt: Project No. 103-225. Final rept. (Unpublished

study received Jan 18, 1984 under 464- 596; prepared by Wildlife International

Ltd., submitted by Dow Chemical U.S.A., Midland, MI; CDL:252291-G) 

41644402 Driscoll, C.; Foster, J.; Hoxter, K. et al. (1990) 2,4-Dichlorophe- noxyacetic

Acid, Triisopropanolamine Salt: A Dietary LC50 Study with the Northern

Bobwhite: Lab Project Number: 103/327. Unpub- lished study prepared by

WildLife International Ltd. 17 p. 

41644403 Driscoll, C.; Foster, J.; Hoxter, K. et al. (1990) 2,4-Dichlorophe- noxyacetic

Acid, Triisopropanolamine Salt: A Dietary LC50 Study with the Mallard: Lab

Project Number: 103/328. Unpublished study prepared by Wildlife International

Ltd. 17 p. 

41448401 Grimes, J.; Culotta, J.; Hoxter, K.; et al. (1990) 2,4-Dichloro- phenoxyacetate

Acid, Butoxyethyl Ester: A Dietary LC50 Study with the Northern Bobwhite:

Lab Project Number: 103-316. Unpub- lished study prepared by Wildlife

International Ltd. 20 p. 
2,4-D Bibliography

Page 290 of 304

41429007 Grimes, J.; Culotta, J.; Hoxter, K. et al. (1990) 2,4-Dichlorophe- noxyacetic

Acid, Butoxyethyl Ester: A Dietary LC50 Study with the Mallard: Lab Project

Number: 103-317. Unpublished study prepared by Wildlife International Ltd. 20

p.

41158305 Beavers, J. (1984) (2,4-Dichlorophenoxy) Acetic Acid Isooctyl Ester: A Dietary

LC50 Study with the Bobwhite Quail: Project Study ID: 103-227. Unpublished

study prepared by Wildlife International Ltd. 16 p. 

45070 Fink, R. (1976) Final Report: Eight-Day Dietary LC50--Mallard Duck: Project

No. 117-114. (Unpublished study received Oct 28, 1976 under 400-134;

prepared by Wildlife International, Ltd., sub- mitted by Uniroyal Chemical,

Bethany, Conn.; CDL:226397-E) 

41158304 Beavers, J. (1984) (2,4-Dichlorophenoxy) Acetic Acid Isooctyl Ester: A Dietary

LC50 Study with the Mallard: Project Study ID: 103-228. Unpublished study

prepared by Wildlife International Ltd. 17 p. 

43934901 Palmer, S.; Beavers, J. (1996) 2,4-D Isopropyl Ester: A Dietary LC50 Study

with the Northern Bobwhite: Lab Project Number: 435-101: WIL-233002:

435/100292/QLCSDT.WC/CHP105. Unpublished study prepared by Wildlife

International Ltd. 68 p. 

43935201 Palmer, S.; Beavers, J. (1996) 2,4-D Isopropyl Ester: A Dietary LC50 Study

with the Mallard: Lab Project Number: 435-102:

435/100295/MLCSDT.WC/CHP105. Unpublished study prepared by Wildlife

International Ltd. 68 p. 

45336401 Mitchell, L.; Beavers, J.; Martin, K. et al. (1999) 2,4-D Acid: A Reproduction

Study with the Northern Bobwhite: Final Report: Lab Project Number: 467-106.

Unpublished study prepared by Wildlife International, Ltd. 181 p. 

44517304 Palmer, S.; Krueger, H. (1997) 2,4-D Dimethylamine Salt: An Acute Contact

Toxicity Study with the Honey Bee: Lab Project Number: 467-102:

467/052297/BLDNC.EFA/SUB467. Unpublished study prepared by Wildlife

International Ltd. 32 p. {OPPTS 850.3020} 

44517301 Palmer, S.; Krueger, H. (1997) 2,4-D 2-Ethylhexyl Ester: An Acute Contact

Toxicity Study with the Honey Bee: Lab Project Number: 467-104.

Unpublished study prepared by Wildlife International Ltd. 34 p._{OPPTS

850.3020}

42416802 Backus, P. (1992) Effect of 2,4-D Acid on Seed Germination/Seedling

Emergence: Tier II: Lab Project Number: 5097-91-0389-BE-001: 91-0389.

Unpublished study prepared by Ricerca, Inc. 223 p. 

42416801 Backus, P. (1992) Effect of 2,4-D Acid on Vegetative Vigor of Plants: Tier II:

Lab Project Number: 91-0390: 5097-91-0390-BE-001. Unpublished study

prepared by Ricerca, Inc. 124 p. 
2,4-D Bibliography

Page 291 of 304

42609101 Backus, P. (1992) Effect of 2,4-D DEAS on Seed Germination/Seedling

Emergence (Tier II): Lab Project Number: 5283-92-0155-BE-001: 92-0155.

Unpublished study prepared by Ricerca, Inc. 210 p. 
Page 292 of 304

Appendix E. Generic Data Call-In
Page 293 of 304

Appendix E.

The generic data call-in will be posted at a later date.
Page 294 of 304

Appendix F. Product Specific Data Call-In
Page 295 of 304

Appendix F.

The product specific data call-in will be posted at a later date.
Page 296 of 304

Appendix G. EPA’s Batching of 2,4-D Products for Meeting Acute Toxicity Data

Requirements for Reregistration
Page 297 of 304

Appendix G. 

The batching of 2,4-D products for meeting acute toxicity data requirements for reregistration will be

posted at a later date.
Page 298 of 304

Appendix H. List of Registrants Sent This Data Call-In
Page 299 of 304

Appendix H. 

A list of registrants sent this data call-in will be posted at a later date. 
Page 300 of 304

Appendix I. List Of Available Related Documents And Electronically Available Forms
Page 301 of 304

Appendix I. 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@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

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 Registrants

for Development of Data

http://www.epa.gov/opprd001/forms/8570-32.pdf

8570-34 Certification with Respect to Citations

of Data (PR Notice 98-5)

http://www.epa.gov/opppmsd1/PR_Notices/pr98-

5.pdf
Page 302 of 304

8570-35 Data Matrix (PR Notice 98-5) http://www.epa.gov/opppmsd1/PR_Notices/pr98-

5.pdf

8570-36 Summary of the Physical/Chemical

Properties (PR Notice 98-1)

http://www.epa.gov/opppmsd1/PR_Notices/pr98-

1.pdf

8570-37 Self-Certification Statement for the

Physical/Chemical Properties (PR

Notice 98-1)

http://www.epa.gov/opppmsd1/PR_Notices/pr98-

1.pdf

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 

4. General Pesticide Information (Some of these forms are in PDF format and will

require the Acrobat reader). 

a. Registration Division Personnel Contact List

b. Biopesticides and Pollution Prevention Division (BPPD) Contacts

c. Antimicrobials Division Organizational Structure/Contact List 

d. 53 F.R. 15952, Pesticide Registration Procedures; Pesticide Data Requirements (PDF format) e. 40 CFR Part 156, Labeling Requirements for Pesticides and Devices (PDF format) 

f. 40 CFR Part 158, Data Requirements for Registration (PDF format) 

g. 50 F.R. 48833, Disclosure of Reviews of Pesticide Data (November 27, 1985) 
Page 303 of 304

Before submitting your application for registration, you may wish to consult some additional

sources of information. These include: 

1. The Office of Pesticide Programs' website. 

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. 

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 website. 

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 (800) 858-7378 or through their website:

ace.orst.edu/info/nptn.

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; and

• 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 chemical abstract system (CAS)

number if one has been assigned.

Documents Associated with this RED 

The following documents are part of the Administrative Record for this RED document and

may be 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

respective Chemical Status Sheet.

1. Detailed Label Usage Information System (LUIS) Report.
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