Document ID: EPA-HQ-OPP-2005-0163-0157
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-11-15T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

MEMORANDUM

             PC Code:    098301

						                         DP Barcode: 332265

SUBJECT:		Environmental Fate and Effects Division

			Aldicarb Revised RED 

			

FROM:		Jonathan Angier

			Jeannette Martinez

			Donna Randall

			Environmental Risk Branch II

	Environmental Fate and Effects Division 

TO:			Bob McNally, Branch Chief

Ann Overstreet, Team Leader

Sherrie Kinard, Chemical Review Manager

Special Review Branch

			Special Review and Reregistration Division 

THROUGH:		Dana Spatz, RAPL

			Tom Bailey, Ph.D., Branch Chief

			Environmental Risk Branch II

			Environmental Fate and Effects Division 

DATE:			September 27th, 2006

The EFED revised risk assessment for aldicarb is attached.  

Risk conclusions can be found in the Executive Summary on page 4.

Data gaps are as follows:

Aldicarb

71-4(a) 		Avian reproduction study with aldicarb - Quail

71-4(b) 		Avian reproduction study with aldicarb - Duck

121-1(a)	Seedling emergence Tier I studies with aldicarb - 10 species

121-1(b)	Vegetative vigor Tier I studies with aldicarb - 10 species

122-2		Aquatic plant growth Tier I studies with aldicarb- 5 species



ALDICARB

Ecological Risk Assessment 

Jonathan Angier

Diana Eignor

Michelle Embry

Jeannette Martinez

Donna Randall

Dana Spatz

Nelson Thurman

Approved By:

Thomas A. Bailey, Chief

Environmental Risk Branch 2 

Environmental Fate and Effects Division

September 27th, 2006

TABLE OF CONTENTS

  TOC \f \* MERGEFORMAT \l "1-4"  I. 	EXECUTIVE SUMMARY	  PAGEREF
_Toc144089010 \h  3 

II.	PROBLEM FORMULATION	  PAGEREF _Toc144089011 \h  3 

A.	Introduction	  PAGEREF _Toc144089012 \h  3 

B.	Stressor Source and Distribution	  PAGEREF _Toc144089013 \h  3 

1.	Chemical and Physical Properties	  PAGEREF _Toc144089014 \h  3 

2.	Mode of Action	  PAGEREF _Toc144089015 \h  3 

3.	Regulatory History	  PAGEREF _Toc144089016 \h  3 

4.	Use Characterization	  PAGEREF _Toc144089017 \h  3 

5.	Measurement Endpoints	  PAGEREF _Toc144089018 \h  3 

6.	Listed Species	  PAGEREF _Toc144089019 \h  3 

C.	Conceptual Model	  PAGEREF _Toc144089020 \h  3 

1.	Terrestrial Environment	  PAGEREF _Toc144089021 \h  3 

a.	Exposure	  PAGEREF _Toc144089022 \h  3 

b.	Receptors of Concern	  PAGEREF _Toc144089023 \h  3 

c.	Terrestrial Environment Risk Hypotheses for Granular Aldicarb Uses	 
PAGEREF _Toc144089024 \h  3 

2.	Aquatic Environment	  PAGEREF _Toc144089025 \h  3 

a.	Exposure	  PAGEREF _Toc144089026 \h  3 

b.	Receptors of Concern	  PAGEREF _Toc144089027 \h  3 

c.	Aquatic Environment Risk Hypotheses for Granular Aldicarb Uses	 
PAGEREF _Toc144089028 \h  3 

D.	Key Uncertainties and Information Gaps	  PAGEREF _Toc144089029 \h  3 

1.	Ecotoxicity Information Gaps	  PAGEREF _Toc144089030 \h  3 

2.	Environmental Fate Information Gaps	  PAGEREF _Toc144089031 \h  3 

E.	Analysis Plan	  PAGEREF _Toc144089032 \h  3 

1.	Specific Considerations	  PAGEREF _Toc144089033 \h  3 

2.	Assessment Endpoints	  PAGEREF _Toc144089034 \h  3 

a.	Toxicity Endpoints	  PAGEREF _Toc144089035 \h  3 

3.	Planned Analyses	  PAGEREF _Toc144089036 \h  3 

a.	Fate and Exposure	  PAGEREF _Toc144089037 \h  3 

b.	Risk Quotient and Levels of Concern	  PAGEREF _Toc144089038 \h  3 

III. 	ANALYSIS	  PAGEREF _Toc144089039 \h  3 

A.	Exposure Characterization	  PAGEREF _Toc144089040 \h  3 

1.	Environmental Fate and Transport Characterization	  PAGEREF
_Toc144089041 \h  3 

a.	Persistence	  PAGEREF _Toc144089042 \h  3 

b.	Mobility	  PAGEREF _Toc144089043 \h  3 

2.	Aquatic Resource Exposure Assessment	  PAGEREF _Toc144089044 \h  3 

3.  	Terrestrial Organism Exposure Modeling	  PAGEREF _Toc144089045 \h 
3 

B.  	Ecological Effects Characterization	  PAGEREF _Toc144089046 \h  3 

1.	Evaluation of Aquatic Ecotoxicity Studies	  PAGEREF _Toc144089047 \h 
3 

a.	Toxicity to Freshwater Animals	  PAGEREF _Toc144089048 \h  3 

b.	Toxicity to Estuarine and Marine Animals	  PAGEREF _Toc144089049 \h 
3 

c.	Toxicity to Aquatic Plants	  PAGEREF _Toc144089050 \h  3 

2.	Evaluation of Terrestrial Ecotoxicity Studies	  PAGEREF _Toc144089051
\h  3 

a.	Toxicity to Terrestrial Animals	  PAGEREF _Toc144089052 \h  3 

b.	Toxicity to Terrestrial Plants	  PAGEREF _Toc144089053 \h  3 

3.	Terrestrial Behavioral Studies	  PAGEREF _Toc144089054 \h  3 

4.	Use of the Probit Slope Response Relationship	  PAGEREF _Toc144089055
\h  3 

5.	Incident Data Review	  PAGEREF _Toc144089056 \h  3 

IV.	RISK CHARACTERIZATION	  PAGEREF _Toc144089057 \h  3 

A.	Risk Estimation - Integration of Exposure and Effects Data	  PAGEREF
_Toc144089058 \h  3 

1.	Non-target Aquatic Animals	  PAGEREF _Toc144089059 \h  3 

a.	Freshwater Fish	  PAGEREF _Toc144089060 \h  3 

b.	Freshwater Invertebrates	  PAGEREF _Toc144089061 \h  3 

c.	Estuarine/Marine Fish	  PAGEREF _Toc144089062 \h  3 

d.	Estuarine/Marine Invertebrates	  PAGEREF _Toc144089063 \h  3 

e.	Risk Quotients Based on Surface Water Monitoring Data	  PAGEREF
_Toc144089064 \h  3 

2.	Non-target Terrestrial Animals	  PAGEREF _Toc144089065 \h  3 

3.	Non-target Terrestrial Invertebrates	  PAGEREF _Toc144089066 \h  3 

a.	Honeybee	  PAGEREF _Toc144089067 \h  3 

b.	Earthworm	  PAGEREF _Toc144089068 \h  3 

4.	Non-target Terrestrial and Aquatic Plants	  PAGEREF _Toc144089069 \h 
3 

B.	Risk Description - Interpretation of Direct Effects	  PAGEREF
_Toc144089070 \h  3 

1.	Risks to Aquatic Animals	  PAGEREF _Toc144089071 \h  3 

2.  	Risks to Terrestrial Animals	  PAGEREF _Toc144089072 \h  3 

C.	Threatened and Endangered Species Concerns	  PAGEREF _Toc144089073 \h
 3 

1.	Taxonomic Groups Potentially at Risk	  PAGEREF _Toc144089074 \h  3 

1.	USFWS Biological Opinions	  PAGEREF _Toc144089075 \h  3 

2.	Probit Slope Analysis	  PAGEREF _Toc144089076 \h  3 

4.	Critical Habitat	  PAGEREF _Toc144089077 \h  3 

5.	Indirect Effect Analyses	  PAGEREF _Toc144089078 \h  3 

a.	Aquatic Species	  PAGEREF _Toc144089079 \h  3 

b.	Terrestrial Species	  PAGEREF _Toc144089080 \h  3 

D.	Description of Assumptions, Uncertainties, Strengths, and Limitations
  PAGEREF _Toc144089081 \h  3 

1.	Assumptions and Limitations Related to Exposure for all Taxa	 
PAGEREF _Toc144089082 \h  3 

2.	 Assumptions and Limitations Related to Exposure for Aquatic Species	
 PAGEREF _Toc144089083 \h  3 

3.	Assumptions and Limitations Related to Exposure for Terrestrial
Species	  PAGEREF _Toc144089084 \h  3 

4.	Assumptions and Limitations Related to Effects Assessment	  PAGEREF
_Toc144089085 \h  3 

5.	Assumptions Associated with the Acute LOCs	  PAGEREF _Toc144089086 \h
 3 

6.	Data Gaps and Limitations of the Risk Assessment	  PAGEREF
_Toc144089087 \h  3 

V.	REFERENCES	  PAGEREF _Toc144089088 \h  3 

 

APPENDICES

Appendix A:	Aldicarb Registration Information

Appendix B:	Environmental Fate Data Requirements

Appendix C:	Ecotoxicity Data Requirements

Appendic D:	PRZM-EXAMS Modeling

Appendix E:	Terrestrial Exposure and RQ Calculation - T-REX Model

Appendix F:	Aldicarb Incidents

Appendix G:	Fugacity Approach for Earthworm Pesticide Residue Modeling

Appendix H:	Endangered Species

Appendix I:	Open Literature (ECOTOX) - Studies that passed OPP/EFED
screening

Appendix J:	Open Literature (ECOTOX) - Studies included in ECOTOX but
rejected by OPP/EFED screening

Appendix K:	Open Literature (ECOTOX) - Studies rejected by ECOTOX

Appendix L:	Rationale for use of open literature (ECOTOX) - Studies used
quantitatively and qualitatively

LIST OF TABLES

  TOC \f E\h    HYPERLINK \l "_Toc144089089"  Table 1.  Currently
registered aldicarb end-use products	  PAGEREF _Toc144089089 \h  3  

  HYPERLINK \l "_Toc144089090"  Table 2.  Maximum and average aldicarb
use rates for specific aldicarb formulations and crops	  PAGEREF
_Toc144089090 \h  3  

  HYPERLINK \l "_Toc144089091"  Table 3.  Aldicarb Typical State and
Crop Use Information - food-use crops (BEAD Quantitative Usage Analysis,
August 9, 2004)	  PAGEREF _Toc144089091 \h  3  

  HYPERLINK \l "_Toc144089092"  Table 4.  Summary of Assessment and
Measurement Endpoints used in calculations	  PAGEREF _Toc144089092 \h  3
 

  HYPERLINK \l "_Toc144089093"  Table 5.  Aldicarb application methods
and incorporation efficiency	  PAGEREF _Toc144089093 \h  3  

  HYPERLINK \l "_Toc144089094"  Table 6.  Formulas for RQ calculations
and LOC used for risk assessment of aldicarb	  PAGEREF _Toc144089094 \h 
3  

  HYPERLINK \l "_Toc144089095"  Table 7.  Selected physical and chemical
properties of aldicarb	  PAGEREF _Toc144089095 \h  3  

  HYPERLINK \l "_Toc144089096"  Table 8.  PRZM/EXAMS input parameters	 
PAGEREF _Toc144089096 \h  3  

  HYPERLINK \l "_Toc144089097"  Table 9.  Surface water EECs for
aldicarb	  PAGEREF _Toc144089097 \h  3  

  HYPERLINK \l "_Toc144089098"  Table 10.  Terrestrial EECs for
aldicarb, calculated based on application method, application rate
(maximum and average), and % unincorporation of granules	  PAGEREF
_Toc144089098 \h  3  

  HYPERLINK \l "_Toc144089099"  Table 11.  Acute Toxicity Endpoints for
Freshwater Fish	  PAGEREF _Toc144089099 \h  3  

  HYPERLINK \l "_Toc144089100"  Table 12.  Chronic Toxicity Endpoints
for Freshwater Fish	  PAGEREF _Toc144089100 \h  3  

  HYPERLINK \l "_Toc144089101"  Table 13.  Acute Toxicity Endpoints for
Freshwater Invertebrates	  PAGEREF _Toc144089101 \h  3  

  HYPERLINK \l "_Toc144089102"  Table 14.  Chronic Toxicity Endpoints
for Freshwater Invertebrates	  PAGEREF _Toc144089102 \h  3  

  HYPERLINK \l "_Toc144089103"  Table 15.  Acute Toxicity Endpoints for
Estuarine and Marine Fish	  PAGEREF _Toc144089103 \h  3  

  HYPERLINK \l "_Toc144089104"  Table 16.  Chronic Toxicity Endpoints
for Estuarine and Marine Fish	  PAGEREF _Toc144089104 \h  3  

  HYPERLINK \l "_Toc144089105"  Table 17.  Acute Toxicity Endpoints for
Estuarine and Marine Invertebrates	  PAGEREF _Toc144089105 \h  3  

  HYPERLINK \l "_Toc144089106"  Table 18.  Chronic Toxicity Endpoints
for Estuarine and Marine Invertebrates	  PAGEREF _Toc144089106 \h  3  

  HYPERLINK \l "_Toc144089107"  Table 19.  Toxicity Endpoints for
Aquatic Plants	  PAGEREF _Toc144089107 \h  3  

  HYPERLINK \l "_Toc144089108"  Table 20.   Toxicity Endpoints Used in
the Risk Assessment	  PAGEREF _Toc144089108 \h  3  

  HYPERLINK \l "_Toc144089109"  Table 21.  Acute and chronic risk
quotients for freshwater fish	  PAGEREF _Toc144089109 \h  3  

  HYPERLINK \l "_Toc144089110"  Table 22.  Acute Risk Quotients for
Freshwater Invertebrates	  PAGEREF _Toc144089110 \h  3  

  HYPERLINK \l "_Toc144089111"  Table 23.  Chronic risk quotients for
freshwater invertebrates.	  PAGEREF _Toc144089111 \h  3  

  HYPERLINK \l "_Toc144089112"  Table 24.   Acute and chronic risk
quotients for estuarine/ marine fish	  PAGEREF _Toc144089112 \h  3  

  HYPERLINK \l "_Toc144089113"  Table 25.   Acute and chronic risk
quotients for estuarine/ marine invertebrates	  PAGEREF _Toc144089113 \h
 3  

  HYPERLINK \l "_Toc144089114"  Table 26.  Acute risk quotients for
aquatic organisms based on actual field data.	  PAGEREF _Toc144089114 \h
 3  

  HYPERLINK \l "_Toc144089115"  Table 27.  Avian Acute Risk Quotients
for Aldicarb (maximum and average use rates).	  PAGEREF _Toc144089115 \h
 3  

  HYPERLINK \l "_Toc144089116"  Table 28.  Mammalian Acute Risk
Quotients for Aldicarb (maximum and average use rates	  PAGEREF
_Toc144089116 \h  3  

  HYPERLINK \l "_Toc144089117"  Table 29.  Ranges of Acute Avian and
Mammalian Risk Quotients	  PAGEREF _Toc144089117 \h  3  

  HYPERLINK \l "_Toc144089118"  Table 30.  Number of wildlife carcasses
found in a 1987 field study on the hazard of aldicarb to terrestrial
wildlife	  PAGEREF _Toc144089118 \h  3  

  HYPERLINK \l "_Toc144089119"  Table 31.  Tabulation by taxonomic group
and crop of listed species that occur in aldicarb use areas	  PAGEREF
_Toc144089119 \h  3  

 

LIST OF FIGURES

  TOC \f D\h    HYPERLINK \l "_Toc144028500"  Figure 1.  Chemical
structure of aldicarb and its oxidative transformation products	 
PAGEREF _Toc144028500 \h  3  

  HYPERLINK \l "_Toc144028501"  Figure 2.  Ecological conceptual model
for the application of aldicarb to agricultural fields.  Solid arrows
indicate pathways addressed in this assessment quantitatively.  Dashed
arrows indicate potential exposure pathways that were not addressed
quantitatively.	  PAGEREF _Toc144028501 \h  3  

 

I. 	EXECUTIVE SUMMARY  TC \l1 "I. 	EXECUTIVE SUMMARY 

Aldicarb (TEMIK®) is a granular systemic insecticide, acaricide, and
nematicide that was first registered for use in 1970, and belongs to the
carbamate class of cholinesterase-inhibiting chemicals.  Aldicarb is
registered for use on numerous crops, including cotton, peanuts,
potatoes, citrus, soybeans, tobacco, sugarcane, and sugar beets. 
Approximately 4.53 millions pounds of aldicarb active ingredient (ai)
are used per year on 5.45 million acres.  The emphasis of this risk
assessment is on aldicarb maximum label rates and average usage rates. 
This document includes an assessment of risks to terrestrial animals
resulting from the use of aldicarb on all federal-label (Section 3)
listed uses: dry beans, cotton, citrus, peanuts, pecans, potatoes,
sorghum, soybeans, sugarbeets, sugarcane, sugarbeets, sweet potatoes,
and ornamentals.  Additionally special local need (SLN; Section 24c)
aldicarb uses including alfalfa, beans, coffee, tobacco, and yams are
noted.  Risks to aquatic organisms are currently assessed based on
modeled estimated environmental concentrations (EECs) for the cotton,
potato, citrus, pecan, and soybean uses of the chemical.  These five
aquatic scenarios were chosen because they include the major aldicarb
use crops and are representative of specific geographic use areas as
well as application rates; other uses should be encompassed by these
scenarios as well.  Actual aldicarb concentrations monitored in a field
study were also used to determine risks to aquatic organisms.

Exposure and Risk to Terrestrial Organisms

The acute risk, acute restricted use, and acute endangered species LOCs
for birds and mammals are exceeded for all target crops at both maximum
allowed label rates and average use rates.  

Acute levels of concern are consistently exceeded by a factor of greater
than 100x and are frequently exceeded by more than 1000x.  

Granules left exposed on the surface appear to be the main source of
exposure, but other sources such as residues taken up by plants and soil
invertebrates (e.g., earthworms) may also serve as a means of exposure.

Aldicarb residues are sufficiently high to exceed levels demonstrated to
be life threatening (e.g., a single granule of TEMIK® 15G can kill a
small bird). 

Exposure and Risk to Aquatic Organisms

There is acute risk for freshwater fish and invertebrates and
estuarine/marine fish and invertebrates for all of the registered uses
with the exception of potatoes for freshwater fish and invertebrates and
estuarine/marine fish.  

The chronic level of concern is exceeded for freshwater invertebrates
(reproductive effects endpoint) and estuarine/marine invertebrates
(average number of offspring endpoint) for all of the registered uses.  

Based on the use of an estimated NOAEC for reproductive effects in
freshwater fish, the chronic level of concern is also exceeded for
freshwater fish (larval and juvenile survival) for soybean, cotton, and
pecan use patterns.

Based on the use of an estimated NOAEC for reproductive effects in
estuarine/marine fish, the chronic level of concern is exceeded for
estuarine/marine fish for all crop scenarios.

Aldicarb residues are most likely to exceed levels of concern for fish
and aquatic invertebrates in low-order streams because these streams are
dominated by baseflow conditions (where 100% of stream flow consists of
discharged groundwater), and most of the toxic residues are believed to
form within the subsurface (especially within the saturated zone) and
are conveyed by groundwater.  Higher-order streams are sustained by much
larger contributing land areas, so there should be a greater dilution
effect.

In addition to risk based exposure estimates from modeling, there were
also exceedances of the Agency levels of concern based monitoring data.

Using Multiple Lines of Evidence (such as use scenarios, average or
“typical” application rates, registrant submitted toxicity studies,
open literature data, and field monitoring data), lead to the same
conclusion: Aldicarb labeled uses pose acute risk (mortality) concerns
to birds, mammals, and aquatic organisms.  In addition, there are acute
and chronic reproductive concerns in fish and aquatic invertebrates.

II.	PROBLEM FORMULATION  TC \l1 "II.	PROBLEM FORMULATION 

	Introduction  TC \l2 "A.	Introduction 

Aldicarb (2-methyl-2-(methylthio)propionaldehyde
O-(methylcarbamoyl)oxime), also known by the trade name TEMIK®, is a
soil-incorporated granular pesticide that was first registered for use
on cotton in 1970.  Aldicarb is an insecticide, acaricide, and
nematicide, and is used in numerous countries on a variety of crops.  In
the U.S., aldicarb is used on alfalfa (in CA only), citrus, cotton, dry
beans, peanuts, pecans, potatoes, sorghum, soybeans, sugar beets,
sugarcane (LA only), sweet potatoes, tobacco (NC and VA only), and
ornamentals.  In U.S. territories, aldicarb is also used on coffee and
yams in Puerto Rico.  The objectives of the current ecological risk
assessment were to identify current registered aldicarb uses, identify
potential exposure pathways and ecological receptors, estimate exposure
concentrations, identify ecological endpoints, and characterize risks
for ecological receptors.  This screening-level risk assessment follows
the Agency’s Ecological Risk Assessment Guidelines (USEPA, 2000). 
This document includes an assessment of risks to terrestrial animals
resulting from the use of aldicarb on all federal-label listed (Section
3) uses: citrus, cotton, dry beans, sorghum, peanuts, pecans, potatoes,
soybeans, sugar beets, sugarcane, sweet potatoes, and ornamentals. 
Special local need (SLN, Section 24c) labels were examined, and the
crops and application rates were determined to be adequately represented
by the aforementioned scenarios.  Risks to aquatic organisms are
assessed based on modeled EECs for the cotton, potato, citrus, pecan,
and soybean uses of the chemical.  These five aquatic scenarios were
chosen because they are the major aldicarb use crops and are
representative of specific geographic use areas as well as application
rates and other uses should be encompassed by these scenarios as well. 
Actual aldicarb concentrations monitored in a field study were also used
to determine risks to aquatic organisms.

Due to the fact that aldicarb is rapidly degraded in the aquatic
environment to aldicarb sulfoxide and aldicarb sulfone, total toxic
aldicarb residues (aldicarb + aldicarb sulfoxide + aldicarb sulfone)
were modeled and evaluated in this screening-level assessment for
aquatic exposure.  Based on the acute toxicity studies for freshwater
fish and invertebrates, aldicarb sulfone is the least toxic of all three
compounds. The invertebrate study suggests that aldicarb and aldicarb
sulfoxide are approximately equally toxic. The fish study suggests that
aldicarb is slightly more toxic than aldicarb sulfoxide, leaving room
for speculation if the difference measured in toxicity is due to lab
variability or actual.  These degradates are unlikely to form in
significant quantities in the terrestrial environment, and therefore
were not modeled for terrestrial risk.  Chemical structures are shown in
Figure 1.  

	



	Stressor Source and Distribution  TC \l2 "B.	Stressor Source and
Distribution 

	Chemical and Physical Properties  TC \l3 "1.	Chemical and Physical
Properties 

	Common Name:				Aldicarb

Chemical Name:				2-methyl-2-(methylthio)propionaldehyde
O-(methylcarbamoyl)oxime

	CAS No.					116-06-3

	PC Code:					098301

	Molecular Formula: 				C7 H14 N2O2S

	Molecular Weight:				190.2 g/mol

	Density:					1.2 g/cm3	

	Melting Point:					100NC

	Boiling Point:					decomposes above 100NC

	Vapor Pressure: 				2.55 x 10-5 mm Hg at 25oC

	Water Solubility:				6,000 mg/L(pH 7, 25 oC)

	Henry's Law Const.: 				1.7x10-10 atm m3/mole

	Octanol-Water Partition Coefficient:		14		

	Formulations:				Granules (e.g. Active ingredient 15.0%, Inert
ingredients 85.0%)

 

Figure 1.  Chemical structure of aldicarb and its oxidative
transformation products  TC "Figure 1.  Chemical structure of aldicarb
and its oxidative transformation products" \f D \l "1"  

2.	Mode of Action  TC \l3 "2.	Mode of Action 

Aldicarb is a systemic insecticide, acaricide, and nematicide, and is
one of the most acutely toxic pesticides currently registered.  It is a
potent cholinesterase (ChE) inhibitor causing reversible inhibition of
erythrocyte acetylcholinesterase (RBC ChE) as well as plasma butyryl ChE
by binding to the active site of the enzyme.  Acetylcholinesterase is an
enzyme necessary for the degradation of the neurotransmitter
acetylcholine (ACh) and subsequent cessation of synaptic transmission. 
Inhibition of these enzymes results in the accumulation of ACh at
cholinergic nerve endings and continual nerve stimulation resulting in
insect death.

	Regulatory History  TC \l3 "3.	Regulatory History 

First registered in 1970, aldicarb use was restricted and is in Special
Review due to ground water contamination concerns.  Position documents
(PD’s) 1 and 2/3 were published on 11-July-1984 and 29-June-1988,
respectively.  

In 1980, aldicarb was voluntarily withdrawn from use in Long Island, NY
due to groundwater contamination concerns

In 1981, aldicarb was classified as a Restricted Use Pesticide

In 1983, use of aldicarb in Del Norte and Humboldt counties (CA) and
Curry county (OR) was prohibited

Aldicarb was voluntarily withdrawn from use in Wisconsin in 1987 due to
drinking water concerns

In 1990, the sale and use of aldicarb on potatoes was voluntarily
suspended due to detection of tolerance-exceeding residues on individual
potatoes

Aldicarb was withdrawn from use in Wisconsin and nine northeastern
states (CT, ME, MA, NH, NJ, NY, PA, RI, VT) due to drinking water
concerns in 1995

Aldicarb use on potatoes was reinstated in Florida, Idaho, Washington,
Oregon, Montana, and several counties in Nevada and Utah in 1995 after
additional studies were conducted to alleviate concerns for dietary risk
due to high residues and implementation of the positive displacement
application method.

The European Union (EU) agreed to phase out the use of aldicarb on March
18, 2003.  Aldicarb will be removed from EU markets by mid-2007 and EU
farmers will stop all use of aldicarb by 2007.  The banning decision was
rendered because of possible impacts on non-target organisms.  In
particular, the high risk of granular aldicarb to small birds was
unacceptable, and the risk to earthworms indicates potential risk to
beneficial arthropods and other soil invertebrates.

	Use Characterization  TC \l3 "4.	Use Characterization 	

Approximately 4.53 millions pounds of aldicarb active ingredient (ai)
are used per year on 5.45 million acres (BEAD Quantitative Usage
Analysis, August 9, 2004).  Aldicarb is used for control of insects,
nematodes and mites on a variety of crops and is applied only in
granular form.  The five crops to which the most pounds of aldicarb are
applied within the United States are, in order, cotton, peanuts,
potatoes, oranges, and sugarbeets.  Aldicarb is also used on a variety
of other crops, such as pecans, sweet potatoes, dry beans, sorghum,
alfalfa, soybeans, sugarcane, tobacco, and other citrus crops (lemons,
limes, and grapefruits), as well as ornamental plants (herbaceous
plants, nonflowering plants, shade trees, woody vines and shrubs). 
States with the most aldicarb use are concentrated in the Southeast (FL,
NC, SC, GA) and the Northwest (WA, ID, CA).  In U.S. territories,
substantial aldicarb use also occurs on coffee in Puerto Rico. 
According to the product labels, aldicarb use is prohibited in
Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York,
Pennsylvania, Rhode Island, Vermont, and Wisconsin.  Also, its use is
prohibited in Del Norte and Humboldt Counties in California, and Curry
County, Oregon.  Additional use restrictions vary by state and by soil,
and prohibit application within some distance (50 to 500 feet; 1000 feet
for citrus crops in FL) of wells used for drinking water.  Technical
aldicarb is formulated and sold as 10 percent or 15 percent ai granules.
 The currently registered products are listed in Table 1. 

Table 1.  Currently registered aldicarb end-use products  TC "Table 1. 
Currently registered aldicarb end-use products" \f E \l "1"  

Registration #	Registration  Name	% of Active Ingredient

264-322	TEMIK® Brand 10G Aldicarb Pesticide	10

264-330	TEMIK® Brand 15G Aldicarb Pesticide	15

264-331	TEMIK® 10% Granular Aldicarb Pesticide for Agricultural Use	10

264-426	TEMIK® Brand 15G Aldicarb Pesticide for Sale and Use in
California only	15

264-417	TEMIK® Brand 15G CP Aldicarb Pesticide	15

264-523	TEMIK® Brand 15G NW Aldicarb Pesticide 	15

Aldicarb is applied by several different methods, all of which involve
soil incorporation of the granules.  Application methods at planting
include in-furrow, band, drill (just below seedline), hill drop, and
shank application.  Side-dressing is used to apply aldicarb to emergent
plants, and band application along the dripline is used for established
trees.  In most cases, aldicarb is applied only once per year to each
crop, with the exception of cotton (which may have 2 applications) and
sugar beets (which may have up to 3 applications).  In both of these
cases a maximum single-application rate and a total yearly application
rate are stated on the label.  Specific use information for each crop
based on maximum labeled use rates, average use rates, number of
applications, and application invervals, where appropriate are listed in
Table 2.  Nation-wide single application rates for aldicarb range from
0.15 lbs active ingredient per acre (lbs ai/A; average application rate)
for certain cotton applications to a maximum of 10.05 lbs ai/A for
pecans.  Aldicarb is effective against numerous pest species, including
aphids, thrips, fleahoppers, leafminers, mites, boll weevils, nematodes,
whiteflies, lygus, potato beetles, bud moths, greenbugs, chinch bugs,
and bean beetles, many of which affect specific crops.   Table 3
provides information on typical state and crop-specific aldicarb use
rates.  

Additionally, there are over 35 Section 24c “Special Local Need”
registrations (allowing use in a specific state) which are summarized in
Appendix A (Tables A-1 and A-2).  All of the use rates indicated on
Section 24c labels fall between the modeled application rates (average
and maximum Section 3 labeled use rates), and are therefore represented
in this risk assessment.

Table 2.  Maximum and average aldicarb use rates for specific aldicarb
formulations and crops  TC "Table 2.  Maximum and average aldicarb use
rates for specific aldicarb formulations and crops" \f E \l "1"  

Crop	TEMIK®

Formulation	EPA Reg #	# of applications (interval)	Maximum labeled rate
(lb ai/A)	Average rate3 (lb ai/A)	Restrictions

citrus	15G CP	264-417	1	4.95	3.7

	

cotton	15G CP	264-417	2 (30 days)	4.95 total

4.05 per app	0.6

15G Lock ‘n Load	264-330	2 (30 days)	4.95 total

4.05 per app	0.6

15G Lock ‘n Load	264-426	2 (30 days)	3.15 total

2.10 per app	0.6	CA only

dry beans	15G CP	264-417	1	2.1	1.0

15G Lock ‘n Load	264-330	1	2.1	1.0

15G Lock ‘n Load	264-330	1	1.05	1.0	CA only

	15G NW	264-523	1	2.10	1.0	ID, NV, OR, UT, WA only

sorghum	15G CP	264-417	1	1.05	0.4

15G Lock ‘n Load	264-330	1	1.05	0.4

15G Lock ‘n Load	264-426	1	1.05	0.4	CA only

peanuts	15G CP	264-417	1	3.0	0.9

15G Lock ‘n Load	264-330	1	3.0	0.9

15G Lock ‘n Load	264-426	1	3.0	0.9	CA only

pecans	15G CP	264-417	1	10.05	3.1	FL max = 4.95

AZ max = 7.05

	15G Lock ‘n Load	264-330	1	10.05	3.1	FL max = 4.95

AZ max = 7.05

potatoes	15G CP	264-417	1	3.0	2.7	FL only

	15G NW	264-523	1	3.0	2.7	ID, NV, OR, UT, WA only

	15G	264-330	1	3.0	2.7	FL, ID, MT, OR, WA, UT, NV

soybeans	15G CP	264-417	1	3.0	0.7

15G Lock ‘n Load	264-330	1	3.0	0.7

15G Lock ‘n Load	264-426	1	3.0	0.7	CA only

sugar beets	15G Lock ‘n Load	264-330	31 (NS)	4.95 total	1.8

15G Lock ‘n Load	264-426	31 (NS)	4.20 total	1.8	CA only

	15G NW	264-523	31 (NS)	4.95 total	1.8	ID, NV, OR, UT, WA only

sugarcane	15G	264-330	1	3.0	NA	LA only

sweet potatoes	15G CP	264-417	1	3.0	1.4

15G Lock ‘n Load	264-330	1	3.0	1.4

15G Lock ‘n Load	264-426	1	3.0	1.4	CA only

ornamentals2	10G Chipco®	264-322	1	5.0	NA	not for use in greenhouses or
potted plants

1Label specifies one at-planting application and 2 postemergence
applications per crop.  No interval is stated on the label.

2Ornamentals include flower crops (e.g. roses), bulbs (e.g. dahlia,
lily), and trees (e.g. birch, holly)

Table 3.  Aldicarb Typical State and Crop Use Information - food-use
crops (BEAD Quantitative Usage Analysis, August 9, 2004)  TC "Table 3. 
Aldicarb Typical State and Crop Use Information - food-use crops (BEAD
Quantitative Usage Analysis, August 9, 2004)" \f E \l "1"  

State

   crop	Acres grown	Total lbs ai applied/yr	Maximum state single
application

rate (lbs ai/A)	Percent

acreage treated

Alabama

   cotton

   peanuts

   pecans	

610,002

190,002

24,064	

180,000

60,000

1,300	

0.7

0.8

0.6	

40

16

3

Arizona

   cotton

   pecans	

242,999

14,502	

51,000

4,400	

1.1

5	

7

7

Arkansas

   cotton

   pecans	

999,995

9,062	

280,000

360	

0.6

1.2	

45

4

California

   alfalfa

   cotton

   dry beans/peas

   pecans

   sugar beets

   sweet potatoes	

943,847

1,056,457

91,420

2,057

159,523

7,420	

680

320,000

2,800

7,600

5,000

310	

0.8

0.8

1.1

5

1.1

3	

1

26

3

62

3

2

Colorado

   dry beans/peas

   sugar beets	

120,000

44,000	

2,600

17,000	

1

1.5	

3

27

Florida

   cotton

   grapefruit

   oranges

   peanuts

   potatoes	

121,001

128,015

727,192

90,000

39,995	

24,000

130,000

350,000

54,000

140,000	

0.8

3.8

3.8

1.1

2.9	

25

2

4

4

52

Georgia

   cotton

   peanuts

   pecans

   sorghum	

1,500,003

540,022

131,873

50,000	

310,000

280,000

180,000

90	

0.6

0.9

3

0.8	

33

37

10

1

Idaho

   dry beans/peas

   potatoes

   sugar beets	

185,000

415,004

210,001	

58,000

130,000

250,000	

1.5

2.9

1.9	

21

10

57

Kansas

   cotton	

29,001	

2,300	

0.6	

13

Louisiana

   cotton

   sugarcane	

569,993

509,999	

120,000

28,000	

0.6

1.7	

34

4

Michigan

   dry beans/peas

   sugar beets	

270,001

193,988	

19,000

11,000	

1

1.8	

7

4

Mississippi

   cotton

   pecans	

1,699,990

11,525	

240,000

3,600	

0.6

2.6	

26

13

Missouri

   cotton	

390,016	

73,000	

0.7	

28

Montana

   dry beans/peas

   sugar beets	

55,000

60,999	

3,800

16,000	

0.6

2.2	

11

12

Nebraska

   sugar beets	

47,998	

8,500	

1.9	

8

Nevada

   potatoes	

12,526	

1,200	

3	

4

New Mexico

   cotton

   peanuts

   pecans	

96,000

23,000

29,622	

17,000

4,800

8,600	

0.7

0.5

4.5	

26

39

2

North Carolina

   cotton

   peanuts

   tobacco	

880,001

125,001

175,801	

440,000

110,000

7,200	

0.7

1

1.6	

69

73

2

North Dakota

  sugar beets	

257,999	

2,200	

1.5	

1

Oklahoma

   cotton

   peanuts

   pecans	

230,006

80,007

83,837	

6,000

7,800

9,700	

0.5

0.9

2.3	

6

7

3

Oregon

   potatoes

   sugar beets	

57,957

15,000	

190,000

12,000	

3

2.6	

58

29

South Carolina

   cotton

   peanuts	

320,001

12,000	

140,000

2,900	

0.7

0.9	

59

23

Tennessee

    cotton	

600,005	

120,000	

0.6	

32

Texas

   cotton

   grapefruit

   oranges

   peanuts

   sorghum	

6,319,982

21,200

9,100

389,995

3,100,013	

520,000

150,000

24,000

32,000

2,400	

0.5

4.7

4.4

0.5

0.5	

17

71

57

6

1

Virginia

   cotton

   peanuts

   tobacco	

110,003

76,000

38,600	

53,000

63,000

14,000	

0.7

1

2.6	

67

58

10

Washington

   dry beans/peas

   potatoes	

110,999

164,998	

20,000

230,000	

1.2

2.9	

15

38

Wyoming

   sugar beets	

61,000	

15,000	

2.6	

9

5.	Measurement Endpoints  TC \l3 "5.	Measurement Endpoints 

Each assessment endpoint requires one or more “measures of ecological
effect,” which are defined as changes in the attributes of an
assessment endpoint itself or changes in a surrogate entity or attribute
in response to pesticide exposure.  Ecological measurement endpoints for
the screening level risk assessment are based on a suite of
registrant-submitted toxicity studies, as well as open literature
review.  The ECOTOX (ECOTOXicity) database is used to identify
additional data from the open literature.  The ECOTOX database is a
user-friendly, publicly-available, quality-assured, comprehensive tool
for locating toxicity data from the open literature and is maintained by
the EPA Mid-Atlantic Ecology Division.  More information on ECOTOX can
be found at:   HYPERLINK http://www.epa.gov/ecotox.
http://www.epa.gov/ecotox.   Research papers are thoroughly screened
using standard procedures before being accepted into ECOTOX, thereby
ensuring consistent, high quality information.  

Toxicity studies used in the risk assessment are needed for the
following broad groupings; typical registrant submitted studies received
for these groups are identified in parentheses:

Birds (mallard duck and bobwhite quail) used as surrogate species for
terrestrial-phase amphibians and reptiles

Mammals (laboratory rat)

Freshwater fish (bluegill sunfish and rainbow trout) used as a surrogate
for aquatic phase amphibians

Freshwater invertebrates (water flea - Daphnia magna)

Estuarine/marine fish (sheepshead minnow)

Estuarine/marine invertebrates (Eastern oyster and mysid shrimp)

Terrestrial plants (corn, onion, ryegrass, wheat, buckwheat, cucumber,
soybean, sunflower, tomato, and turnip)

Algae and aquatic plants (algae, diatoms, and duckweed)

 	Listed Species  TC \l3 "6.	Listed Species 

Potential risks posed by aldicarb use on listed species must be
evaluated.  The potential for individual effects at exposure levels
equivalent to the level of concern (LOC) is evaluated based on the
median lethal dose estimate and dose-response relationship established
for the effects study corresponding to each taxonomic group for which
the LOCs are exceeded.  Proximity of listed species habitats to areas
that grow target crops are also evaluated.

	Conceptual Model  TC \l2 "C.	Conceptual Model 

A conceptual model (CM), which summarizes graphically the results of the
problem formulation for evaluating risks to ecological receptors
following application of granular aldicarb to an agricultural field is
provided in Figure 2.  The CM is a working hypothesis about how aldicarb
is likely to reach (i.e., exposure pathways) and affect ecological
entities (i.e., attribute changes) of concern on and adjacent to a
treated agricultural field.  In order for a pesticide stressor to pose
an ecological risk, it must reach an ecological receptor in biologically
significant concentrations.  The CM outlines specifically which measures
of exposure, ecological receptors, and measures of effects or
measurement endpoints will be used to estimate risks from proposed
reregistration uses of aldicarb.

Based on the crop and pest uses, aldicarb is used on agricultural lands
located in a wide diversity of ecoregions and habitats spanning the
continental United States, Hawaii, and Puerto Rico.  The wide diversity
of land forms and vegetation types across aldicarb use areas also
provides for a large diversity of mammals, birds, reptiles, amphibians,
terrestrial invertebrates, and freshwater and estuarine/marine fish and
invertebrates that could potentially be exposed.  

1.	Terrestrial Environment  TC \l3 "1.	Terrestrial Environment 

	Exposure  TC \l4 "a.	Exposure 

Immediately following granular application of aldicarb and prior to soil
incorporation, granules are expected to be available at the soil surface
on agriculture sites.  Wildlife exposure could result from mistakenly
ingesting granules as seeds or ingesting them as part of incidental soil
ingestion while foraging for food.  Soil incorportion of the granules is
expected to result in the movement of aldicarb down into the soil column
but some granules will still remain available on the surface (i.e. soil
incorporation methods result in <100% incorporation).

Terrestrial organisms will be potentially exposed to aldicarb and
aldicarb residues through multiple pathways, including direct contact
with granules (ingestion, dermal), incidental ingestion of residues in
soil, and secondary contact through ingestion of residues in plant and
soil invertebrates.  Aldicarb is expected to be readily absorbed by
plant roots from the soil and transported through a plant via plant
fluids following application (based on physicochemical properties). 
Additionally, terrestrial organisms may be exposed to aldicarb dissolved
in drinking water pooled on the field surface if application is soon
followed by irrigation or rainfall.  This dissolved aldicarb should
eventually either infiltrate into the subsurface soil (vertical
leaching) or be transported offsite via runoff.  Toxic degradates are
unlikely to form at the surface because the conditions under which
degradation to toxic forms occurs do not commonly exist at the land
surface, so there is less risk of exposure to toxic degradates for
terrestrial organisms.  Currently in a screening-level risk assessment,
terrestrial wildlife exposure is estimated via the amount of toxicant
per unit area.  The level of concern value was developed considering
these other routes of exposure; however, they are not separately
accounted for in the screening-level risk index calculation.

b.	Receptors of Concern  TC \l4 "b.	Receptors of Concern 

Ecological receptors of concern identified for consideration in the
terrestrial environment include primary producers, represented by both
upland and wetland/riparian vegetation, and primary and secondary
consumers, both vertebrates and invertebrates, representing common
ecological functional feeding groups (i.e., herbivores and
insectivores).  Herbivores as used here include animals that feed on
foliage (stems and leaves), seeds, and/or fruit; the term granivore is
sometimes used to identify animals that feed primarily on seeds. 
Omnivores (i.e., consumers that feed on a mixed diet of animals and
plants) are also potentially exposed but are not specifically included
in the receptor list for a screening-level risk assessment because
exposure concentrations and risk levels will fall between the exclusive
feeding groups.  Food chain transfer through biomagnification or
bioaccumulation of aldicarb to higher trophic level predators (e.g.,
carnivores) is not considered as a viable significant exposure pathway
since aldicarb’s octanol-water partition coefficient is low.  A low
octanol-water partition coefficient indicates that the chemical has low
affinity for fatty tissues and is therefore unlikely to biomagnify up
the food chain (e.g., has a low bioconcentration factor, BCF).  However,
bioconcentration in those soil invertebrates and plants in contact with
soil residues or granules will occur.

Based on the sources/transport pathways, exposure media, and potential
receptors of concern, specific questions or risk hypotheses formulated
to characterize direct effects of granular aldicarb following
application on agricultural fields to selected assessment endpoints is
provided below. 

c.	Terrestrial Environment Risk Hypotheses for Granular Aldicarb Uses 
TC \l4 "c.	Terrestrial Environment Risk Hypotheses for Granular Aldicarb
Uses 

Birds and mammals are subject to reduced survival or reduced
reproduction when exposed to aldicarb and/or its metabolites (aldicarb
sulfoxide, aldicarb sulfone) as a result of labeled use.

Upland and riparian/wetland plants are subject to adverse effects
(reduced survival) when exposed to aldicarb and/or its metabolites
(aldicarb sulfoxide, aldicarb sulfone) as a result of labeled use.

	Aquatic Environment  TC \l3 "2.	Aquatic Environment 

	Exposure  TC \l4 "a.	Exposure 

Aldicarb rapidly degrades in the aquatic environment to aldicarb
sulfoxide and aldicarb sulfone, both of which are toxic to aquatic
organisms.  Therefore, exposure to all forms of aldicarb (parent +
sulfoxide + sulfone) must be considered.  Direct application of aldicarb
to streams, lakes, and ponds is forbidden by product labels.  However,
following a rain event, aldicarb may reach aquatic environments from
areas of application in sheet and channel flow runoff since aldicarb is
moderately persistent in terrestrial environments and soluble in water. 
It is unlikely that aquatic organisms will be directly exposed to
granules, both because of the highly soluble nature of the compound
(whole granules will dissolve rather than be transported intact) and the
application methods (directly onto field).  Aquatic organisms could also
be exposed to aldicarb residues and degradates from groundwater that is
subsequently discharged into a surface water body.

For the aquatic ecosystem ecological receptors include all aquatic life
(fish, amphibians, invertebrates, plants) and those terrestrial animals
(e.g., birds and mammals) that consume aquatic organisms.

	Receptors of Concern  TC \l4 "b.	Receptors of Concern 

Based on the above sources/transport pathways, exposure media, and
potential receptors of concern, specific questions or risk hypotheses
formulated to characterize direct effects of aldicarb following
application on agricultural fields to selected assessment endpoints is
provided below.

	Aquatic Environment Risk Hypotheses for Granular Aldicarb Uses  TC \l4
"c.	Aquatic Environment Risk Hypotheses for Granular Aldicarb Uses 

Aquatic invertebrates and fish are subject to adverse effects such as
reduced survival and reduced reproduction when exposed to aldicarb
and/or its metabolites (aldicarb sulfoxide, aldicarb sulfone) as a
result of labeled use.

Aquatic plants are subject to adverse effects (reduced survival) when
exposed to aldicarb and/or its metabolites (aldicarb sulfoxide, aldicarb
sulfone) as a result of labeled use.

 

Figure 2.  Ecological conceptual model for the application of aldicarb
to agricultural fields.  Solid arrows indicate pathways addressed in
this assessment quantitatively.  Dashed arrows indicate potential
exposure pathways that were not addressed quantitatively.  TC "Figure 2.
 Ecological conceptual model for the application of aldicarb to
agricultural fields." \f D \l "1"  



	Key Uncertainties and Information Gaps  TC \l2 "D.	Key Uncertainties
and Information Gaps 

The following uncertainties and information gaps were identified as part
of the problem formulation:

	Ecotoxicity Information Gaps  TC \l3 "1.	Ecotoxicity Information Gaps 

Aldicarb

No avian reproduction toxicity studies (71-4) were submitted to the
Agency.  Avian reproduction studies on the mallard duck and bobwhite
quail using the TGAI are required for aldicarb because the following
conditions are met: (1) birds may be subject to repeated or continuous
exposure to the pesticide, especially preceding or during the breeding
season, and (2) the pesticide is stable in the environment to the extent
that potentially toxic amounts may persist in animal feed.  The
following studies are requested:

71-4(a) Avian Reproduction - Quail

71-4(b) Avian Reproduction – Duck

No plant studies were submitted to the Agency.  Plant toxicity studies
with aldicarb TGAI are required because of potential phytotoxic effects
(delayed emergence and plant stand) identified by the registrant on the
label, the Agency is requesting Tier 1 studies.

121-1(a)	Seedling Emergence - 10 species

121-1(b)	Vegetative Vigor - 10 species

122-2		Aquatic Plant Growth - 5 species

 	Environmental Fate Information Gaps  TC \l3 "2.	Environmental Fate
Information Gaps 

Evaluation of photodegradation in water of aldicarb sulfone and
sulfoxide is important, since these compounds are more persistent than
the parent (aldicarb).  Although it is true that aldicarb sulfoxide and
aldicarb sulfone are more likely to be detected in ground water than
surface water (and thus generally not subject to photodegradation), most
local groundwater eventually discharges into surface water bodies under
baseflow conditions.  Nevertheless, this is unlikely to be a major
issue; although additional studies establishing rates of
photodegradation of aldicarb sulfoxide and aldicarb sulfone in water
would be useful, they are not expected to change risk conclusions.

Appendices B and C at the end of this document provides a summary status
of all the environmental fate and ecotoxicological data requirements,
respectively.

	Analysis Plan  TC \l2 "E.	Analysis Plan 

1.	Specific Considerations  TC \l3 "	1.	Specific Considerations 

This document includes an assessment of risks to terrestrial animals
resulting from the use of aldicarb on all federal-label listed (Section
3) uses:  citrus, cotton, dry beans, sorghum, peanuts, pecans, potatoes,
soybeans, sugar beets, sugarcane, sweet potatoes, and ornamentals. 
Special local need (SLN, Section 24c) labels were examined, and the
crops and application rates were determined to be adequately represented
by the aforementioned scenarios.  Risks to aquatic organisms are
assessed based on modeled EECs for the cotton, potato, citrus, pecan,
and soybean uses of the chemical.  These five aquatic scenarios were
chosen because they are the major aldicarb use crops and are
representative of specific geographic use areas as well as application
rates; other uses should be encompassed by these scenarios as well. 
Actual aldicarb concentrations monitored in a field study were also used
to determine risks to aquatic organisms. 

Ecological risk assessment is a process that evaluates the likelihood
that adverse ecological effects may occur or are occurring as a result
of exposure to one or more stressors (US EPA, 1992a).  This risk
assessment examines the ecological risk of registered aldicarb use, and
attempts to determine at what level aldicarb can be used to minimize
deleterious effects on the environment.  These negative effects include
structural and/or functional characteristics or components of
ecosystems.  In order to estimate the ecological risk associated with
labeled aldicarb use, use information, chemical and physical properties,
and fate/transport data were evaluated.  Toxicity and fate data were
also examined for the aldicarb degradates (sulfone and sulfoxide), where
available.

	Assessment Endpoints  TC \l3 "	2.	Assessment Endpoints 

Assessment endpoints are defined as “explicit expressions of the
actual environmental value that is to be protected.”  Two criteria are
used to select the appropriate ecological assessment endpoints: 1)
identification of the valued attributes of the environment that are
considered to be at risk, and 2) the operational definition of
assessment endpoints in terms of an ecological entity (i.e., a community
of fish and aquatic invertebrates) and its attributes (i.e., survival
and reproduction).  Therefore, the selection of assessment endpoints is
based on valued entities (i.e., ecological receptors), the ecosystems
potentially at risk, the migration pathways of pesticides, and the
routes by which ecological receptors are exposed to pesticide-related
contamination.  The selection of clearly defined assessment endpoints is
important because they provide direction and boundaries in the risk
assessment for addressing risk management issues of concern.

	ToxicityEndpoints  TC \l4 "a.	Toxicity Endpoints 

An effects analysis will be performed to evaluate the available toxicity
data (registrant and public literature) to supply identified measurement
endpoints (Table 4).  Specific values for measurement endpoints will be
selected in the effects analysis from the available test data, as the
data sets allowed.  For this assessment, the most sensitive toxicity
endpoints for each surrogate taxa (ie. freshwater fish and
invertebrates, estuarine/marine fish and invertebrates, aquatic plants,
terrestrial plants, birds, and mammals) will be used in Risk Quotient
(RQ) calculations with appropriate exposure values.  Additional
ecological effects data available from public literature for aldicarb
were incorporated into the risk characterization as other lines of
evidence.

Table 4.  Summary of assessment endpoints and proposed measures of
effects for screening level risk assessment of aldicarb   TC "Table 4. 
Summary of assessment endpoints and proposed measures of effects for
screening level risk assessment of aldicarb" \f E \l "1"  

Assessment Endpoint	Measurement Endpoint

1.  Survival, reproduction, and growth of birds	Acute oral LD50 values

Subacute 5-d dietary LC50 values

Avian reproduction study NOAEL or NOAEC

2.  Survival, reproduction, and growth of mammals	Acute oral mammalian
LD50 values

Mammal chronic (reproduction) study NOAEC or NOAEL

3.  Survival and reproduction of freshwater fish and invertebrates	Acute
freshwater fish 96-h LC50

Acute freshwater invertebrate 96-h LC50 (48-h EC50 for cladocerans such
as Daphnia magna)

Early life-stage or life cycle freshwater fish NOAEC

Full life cycle or reproduction freshwater invertebrate NOAEC

4.    Survival and reproduction of estuarine/marine fish and
invertebrates	Acute estuarine/marine fish 96-h LC50

Early life-stage or life-cycle estuarine/marine fish NOAEC

Acute estuarine/marine invertebrate 96-h LC50

Full life cycle or reproduction estuarine/marine invertebrate NOAEC

5.  Perpetuation of non-target terrestrial plants (crops and non-crop
species)	Monocot and dicot seedling emergence EC25

Monocot and dicot seedling emergence EC05 or NOAEC

Monocot and dicot vegetative vigor IC25

Monocot and dicot vegetative vigor IC05 or NOAEC

6.  Survival of beneficial insect populations	Honey bee acute contact
LD50

7.  Maintenance and growth of aquatic plants from standing crop or
biomass	Aquatic plant growth and biomass 96-h IC50 (14-d for duckweed)

Aquatic plant growth and biomass 96-h IC05 or NOAEC (14-d for duckweed)

LD50 : Lethal dose to 50% of test population

LC50 : Lethal concentration to 50% of the test population

EC50 : median effect concentration is the concentration that results in
a specific effect (e.g., immobility, emergence) to 50% of the exposed
test population

EC05 and EC25 : the concentration that results in a specific effect to
5% and 25%, respectively, of the exposed test population.

IC05, IC25 , and IC50 : the concentration that results in a 5%, 25%, and
50%, respectively, inhibition of a given effect (e.g., weight, length).

NOAEC = No observed adverse effect concentration

ENEC = Estimated no effect concentration

	Planned Analyses

  TC \l3 "	3.	Planned Analyses 

a.	Fate and Exposure  TC \l4 "a.	Fate and Exposure 

Terrestrial Environment

The level of incorporation of aldicarb granules into the soil following
application has the strongest effect on subsequent environmental
exposure, especially to birds and mammals.  Ingestion of granules left
exposed in treated fields represents the most significant exposure
pathway in these animals.  Based on the EPA’s Comparative Analysis of
Acute Avian Risk from Granular Pesticides document (EPA, 1992),
different application methods result in variable incorporation
efficiency, as shown in Table 5.  Additionally, aldicarb granules may be
left exposed on the soil surface when 1) machinery is being loaded, 2)
planter shoes are lifted out of the furrows to permit turning, 3)
planter shoes rise out of the soils of irregularly contoured fields, and
4) machinery is worn or is not operating correctly (EPA, 1992).

The terrestrial screening-level risk assessment examined major crop
uses, including cotton, dry beans, sorghum, peanuts, potatoes, soybeans,
sugar beets, sweet potatoes, citrus, pecans, and ornamentals. Both
maximum labeled use rates and average application rates (BEAD
Quantitative Usage Analysis, August 9, 2004) were examined, using
labeled application methods and parameters (e.g. band width, row
spacing).  Average use rates were not available for ornamental aldicarb
use; therefore, only maximum rates were examined.  Incorporation of the
aldicarb granules was taken into consideration, assuming 99%
incorporation of granules applied in-furrow and 85% incorporation of
granules applied via broadcast soil incorporation or banded applications
(Table 5).  Aldicarb sulfone and aldicarb sulfoxide are not likely to
form in significant quantities in the terrestrial environment, therefore
only parent aldicarb was modeled for terrestrial exposure scenarios.

Table 5.  Aldicarb application methods and incorporation efficiency  TC
"Table 5.  Aldicarb application methods and incorporation efficiency" \f
E \l "1"  

Application Method	Incorporation efficiency

Banded

   covered with a specific amount of soil	99%

In-furrow, drilled, or shanked-in	99%

Side-dress, banded

   mixed or lightly incorporated into soil	85%

Broadcast

   mixed or lightly incorporated into soil	85%

Aquatic Environment

OPP generally uses computer simulation models to estimate exposure of
aquatic organisms, such as plants, fish, aquatic-phase amphibians, and
invertebrates, to a pesticide.  These models calculate estimated
environmental concentrations (EECs) in surface water using laboratory
data that describe the rate at which the pesticide breaks down and how
it moves into the environment.  Monitoring data, if available, may also
be used to determine EECs or to support the model’s calculations.  The
PRZM-EXAMS model is initially used to calculate high-end estimates of
surface water concentrations of pesticide in a generic pond.  This model
was used to generate EECs of total aldicarb residues (parent + sulfoxide
+ sulfone) in surface water.  The User’s Manual and PRZM-EXAMS Model
Description can be consulted for additional information at:   HYPERLINK
http://www.epa.gov www.epa.gov/oppefed1/models/water/index.htm

 

No EECs are generated in instances where no toxicity was observed at
concentrations above the active ingredient’s water solubility.

The following five scenarios representing cotton, potatoes, citrus,
soybeans, and pecans, were used in the standard Pesticide Root Zone
Model and Exposure Analysis Modeling System (PRZM-EXAMS) modeling.  The
modeled use sites (cotton, potatoes, citrus, soybeans, and pecans)
primarily represent the uses where high levels of aldicarb are applied
or sites that are particularly vulnerable to pesticide runoff, leading
to high potential aquatic exposure.  Additionally, the models were run
for each of these crops representing a particular region where it is
commonly grown. 

b.	Risk Quotient and Levels of Concern  TC \l4 "b.	Risk Quotient and
Levels of Concern 

Risk characterization integrates exposure and ecotoxicity data to
evaluate the likelihood of adverse effects.  For ecological effects, the
Agency accomplishes this integration using the quotient risk method. 
Risk quotients (RQs) are calculated by dividing exposure estimates by
acute and chronic ecotoxicity values.  

			RQ = EXPOSURE / TOXICITY

RQs are then compared to the Office of Pesticide Program’s levels of
concern (LOCs) to assess potential risk to non-target organisms and the
need to consider regulatory action.  Calculation of an RQ that exceeds
the LOC indicates that a particular pesticide use poses a presumed risk
to non-target organisms.  LOCs currently address the following
categories of presumed risk:

acute - potential for acute risk is high and regulatory action beyond
restricted use classification may be warranted

acute restricted - the potential for acute risk is high, but may be
mitigated through restricted use classification

acute endangered species - threatened and endangered species may be
adversely affected

chronic risk - the potential for chronic risk is high and regulatory
action may be warranted.  

The ecotoxicity values used in the acute and chronic risk quotients are
measurement endpoints derived from required laboratory toxicity studies
and public literature (Table 4).  Exposure values are those estimated
from planned modeling results and monitoring data discussed in previous
section on the Planned Analysis for Fate and Exposure.  Table 6 gives
LOCs and the specific formulas that will be used for calculating RQs to
evaluate risk presumptions in this screening-level risk assessment.

Table 6.  Formulas for RQ calculations and LOC used for risk assessment
of aldicarb  TC "Table 6.  Formulas for RQ calculations and LOC used for
risk assessment of aldicarb" \f E \l "1"  

Risk Presumption	RQ	LOC

Birds and Wild Mammals

Acute Risk	EEC(a)/LC50 or EEC(b)/LD50 (or EEC(c)/LD50 for exposure to
granules)	0.5

Acute Restricted Use	EEC(a)/LC50 or EEC(b)/LD50 (or EEC(c)/LD50 for
exposure to granules)	0.2

Acute Endangered Species	EEC(a)/LC50 or EEC(b)/LD50 (or EEC(c)/LD50 for
exposure to granules)	0.1

Chronic Risk	EEC (mg ai/kg-diet)/NOAEC (mg ai/kg-diet) or EEC (mg
ai/kg-bw)/NOAEL (mg ai/kg-bw)(d)	1.0

Aquatic Animals

Acute Risk	EEC (ppb ai)/LC50 (ppb ai) or EC50 (ppb ai)	0.5

Acute Restricted Use	EEC (ppb ai)/LC50 (ppb ai) or EC50 (ppb ai)	0.1

Acute Endangered Species	EEC (ppb ai)/LC50 (ppb ai) or EC50 (ppb ai)
0.05

Chronic Risk	EEC (ppb ai)/NOAEC (ppb ai)	1.0

Terrestrial and Plants Inhabiting Semi-Aquatic Areas

Acute Risk	EEC (lbs ai/A)/EC25 (lbs ai/A)	1.0

Acute Endangered Use	EEC (lbs ai/A)/EC05 (lbs ai/A) or NOAEC (lbs ai/A)
1.0

Aquatic Plants

Acute Risk	EEC (ppb ai)/EC50 (ppb ai)	1.0

Acute Endangered Species	EEC (ppb ai)/EC05 or NOAEC (ppb ai)	1.0

EEC: Estimated environmental concentration

(a) Units for EEC, LC50, and NOAEC are milligrams of active ingredient
per kilogram of diet (mg ai/kg-diet)

(b) Units for EEC, LD50, and NOAEL are milligrams of active ingredient
per kilogram of body weight (mg ai/kg-bw)

(c) Units for EEC are milligrams of active ingredient per foot square
(mg ai/ft2) and units for LD50 are mg ai/kg-bw

(d) No chronic RQ on a square foot basis has been developed for exposure
to granules

III. 	ANALYSIS  TC \l1 "III. 	ANALYSIS 

	Exposure Characterization  TC \l2 "A.	Exposure Characterization  

	Environmental Fate and Transport Characterization  TC \l3 "1.
Environmental Fate and Transport Characterization 

Acceptable studies for aldicarb (parent) are not available for all
guidelines, and there are major gaps in the fate data for the two
oxidation products (sulfoxide and sulfone).  However, in part due to the
availability of published studies, sufficient data are available to
allow a preliminary assessment of the environmental fate of aldicarb. 
The status of the data requirements is described in Appendix B. 
Selected physical and chemical properties are summarized in Table 7.

Table 7.  Selected physical and chemical properties of aldicarb  TC
"Table 7.  Selected physical and chemical properties of aldicarb" \f E
\l "1"  

C	Acc 255979

Boiling point	Decomposes above 100C	Acc 255979

Vapor pressure	2.55 10-5 @ 25C

110-4 @ 25C;	MRID 00152095

Acc 225979

Henry’s Law coefficient	1.7x10-10 atm-m3/mol	Acc 255979

Octanol-Water Partition coefficient (Kow) Do Coeff	14

19 (by reverse phase TLC)	Acc 255979

Solubility	6,000 mg/L	Acc 255979

CAS Number	116-06-3	MRID 00152095

a. 	Persistence  TC \l4 "a.	Persistence 

Aerobic soil metabolism is the primary dissipation route for parent
aldicarb in unsaturated soil.  For example, in a sandy loam soil,
aldicarb degraded with a half-life of 2.3 days (MRID 44005001) to the
major oxidative transformation products (85-90% of applied) aldicarb
sulfoxide and aldicarb sulfone.  No further degradation of these
compounds was observed through the end of the study (60 days).  Other
studies have reported half-lives for parent aldicarb ranging from 1 to
28 days (MRIDs 00102051, 00093642, 00080820, 00093640, 00053366,
00101934, 00035365, and 00102071).  At this time EFED lacks valid
guideline studies with data sufficient for estimating formation and
decline rates of the sulfoxide and sulfone.  However, the rapid
oxidation of parent aldicarb to these forms, and their substantially
greater persistence than the parent have been well documented in the
published literature (e.g. Bull et al., 1970; Smelt et al., 1979).  

Laboratory studies suggest that degradation of all three aldicarb forms
(parent, sulfoxide, and sulfone) to relatively non-toxic, non-carbamate
residues (oximes and nitriles) occurs slowly (t1/2 up to 3 months) in
aerobic soils, as a result of soil-catalyzed hydrolysis rather than
aerobic metabolism (Lightfoot et al., 1987; Bank and Tyrrell, 1984).  In
Guideline studies, parent aldicarb was generally stable to hydrolysis,
slowly (at a rate too slow to calculate a half-life – less than 10% at
30 days) hydrolyzing only at a pH of 9 (MRID 00102065).  Aldicarb
sulfoxide hydrolyzed more quickly (t1/2 = 2.3 days) at pH 9 than at pH 7
(about 6% at 28 days) (MRID 00102066).  Aqueous photolysis rapidly
degraded aldicarb to oxime and nitrile forms (i.e. with a t1/2 of four
days: MRID 42498201).  However, this process will only be dominant in
clear, shallow waters, and will not affect residues in the subsurface.

At this time, EFED lacks valid guideline data on the aquatic metabolism
of aldicarb.  However a published laboratory study reported half-lives
ranging from 70 to 173 days in aerobic Dutch surface waters (Vink et
al., 1997).  In a guideline laboratory anaerobic aquatic metabolism
study (MRID 43805701) aldicarb degraded into acid, nitrile and alcohol
forms, with a half life of 3 hours.  No sulfone or sulfoxide were formed
in this study, suggesting that anaerobic degradation can detoxify
aldicarb residues very rapidly.  The value of this study is in doubt,
though; redox potential was inconsistent and variable throughout the
study period (127 days), contrary to guideline requirements.  In
addition, no discernable pattern of formation and decline of degradates
was observed (data were highly variable and inconsistent).  However,
fate of the parent aldicarb under anaerobic aquatic conditions
(particularly groundwater) is of less concern than that of the
degradates (aldicarb sulfoxide and aldicarb sulfone), which have been
detected in groundwater long after application of the parent chemical
had ceased (e.g., degradates detected in Long Island, NY groundwater
decades after usage was stopped).  In addition, anaerobic aquatic
metabolism studies performed specifically on the toxic degradates
aldicarb sulfoxide and aldicarb sulfone (MRID 45592110 and 45592111),
which yielded half-lives of 3.4 and 3.5 days respectively, also
indicated that a potentially toxic metabolite of aldicarb sulfone,
hydroxymethyl aldicarb sulfone, was formed.  This compound comprised
15-19% of the starting material after 7 days, and did not measurably
decrease thereafter for the remainder of the 30-day study period
(half-life unknown).  This metabolite (hydroxymethyl aldicarb sulfone)
appears to be stable in both anaerobic and aerobic aquatic environments,
with no measurable decrease observed in a 37-day aerobic aquatic
metabolism study (MRID 45592109), and 25-28% of the starting material
(aldicarb sulfone) converted to this compound within the first 10 days. 
An aerobic aquatic metabolism study conducted for the aldicarb
degradation product aldicarb sulfoxide (MRID 45592108) indicated a
half-life of 5 days.  Published studies have also reported increased
degradation rates under low redox conditions, perhaps due to catalysis
by reduced metal species in these environments (Bromilow et al., 1986). 
For example, Smelt et al. (1983) reported laboratory half-lives of
aldicarb sulfone and sulfoxide ranging from 2 to 131 days in Dutch
subsoils under “anaerobic conditions” (310 mV), and from 84 to 1100
days under aerobic conditions.  Given this information, it is likely
that aldicarb sulfoxide and aldicarb sulfone, relatively slowly
degrading in aerobic soil (MRID 44005001), can gradually leach into
groundwater and continue to provide detectable levels of these materials
over long time periods.  The metabolite hydroxymethyl aldicarb sulfone,
which forms from aldicarb sulfone under both aerobic and anaerobic
aquatic conditions, can persist for long periods in oxic, suboxic, and
anoxic groundwater within aquifers, which may account for their
detection long after aboveground application of the parent aldicarb has
been terminated.

In published field studies, dissipation half-lives for total aldicarb
residues in soil have ranged from approximately 0.3 to 5 months in the
unsaturated zone, and 1 to 36 months in the saturated zone (Jones and
Estes, 1995), in apparent contradiction of the observation of faster
degradation under anaerobic (saturated) conditions.  The reasons for the
extreme variability in reported transformation rates (3 hours to 36
months) for aldicarb residues under anaerobic/saturated conditions are
not known, but may be related to temperature, pH, and the presence of
soils for surface catalysis (Lightfoot, et al., 1987).  However,
monitoring data in areas with historical aldicarb contamination confirm
the high persistence of total aldicarb residues in ground water.  For
example, twenty years after cessation of aldicarb use on Long Island,
aldicarb sulfone and sulfoxide are still the most frequently detected
pesticide compounds in ground water there (Suffolk County Dept. of
Health Services, 2000).

Degradation of parent compound aldicarb to aldicarb sulfoxide, and,
subsequently, aldicarb sulfoxide to aldicarb sulfone, each occur at
different rates and to varying extents under different conditions. 
Since each compound is toxic, and each is formed from the previous, it
is necessary to treat the half-lives for all additively.  Thus,
half-lives used for modeling the environmental fate of aldicarb account
for degradation of parent through each degradate of concern, for a
half-life reflecting total toxic residues.  The range for field
dissipation of total aldicarb residues considered in this document,
derived from Jones and Estes 1995, is 15-105 days.  The aerobic soil
half-life used for model inputs, however, is 55 days, derived from the
upper 90th pct bound on mean for total aldicarb residue half-lives from
19 soils.  Since differences in soil temperatures in the northern and
southern U.S. are muted during the summer (a growing season in both
north and south), and variations in soil temperatures diminish with
increasing depth, this value should apply throughout the country.

b. 	Mobility  TC \l4 "b.	Mobility 

Aldicarb and its oxidation products are all highly mobile in soil. 
Aldicarb itself had Freundlich Kads values ranging between 0.20 ml/g for
sand and 0.60 ml/g for clay (MRID 42498202).  Aldicarb sulfoxide had
Freundlich Kads values between 0.17 ml/g on a sandy loam soil and 0.36
ml/g on a sandy clay loam soil (MRID 43560301).  Aldicarb sulfone had
slightly lower values ranging between 0.12 ml/g and 0.22 ml/g on the
same set of soils used for the sulfoxide (MRID 43560302).

	Aquatic Resource Exposure Assessment  TC \l3 "2.	Aquatic Resource
Exposure Assessment 

Aquatic Organism Exposure Modeling:  Tier II EECs for aldicarb were
estimated using EFED’s aquatic models PRZM-EXAMS (EXposure Analysis
Modeling System).  PRZM is used to simulate pesticide transport as a
result of runoff and erosion from an 10-ha agricultural field, and EXAMS
considers environmental fate and transport of pesticides in surface
water and predicts EECs in a standard pond (10,000-m2 pond, 2-m deep),
with the assumption that the small field is cropped at 100%. 
Calculations are carried out with the linkage program shell - PE4VO1.pl
- which incorporates the standard scenarios developed by EFED. 
Additional information on these models can be found at:   HYPERLINK
http://www.epa.gov/oppefed1/models/water/index.htm
http://www.epa.gov/oppefed1/models/water/index.htm .and in Appendix D.

The terrestrial crops for which aldicarb is registered include cotton,
peanuts, potatoes, pecans, soybeans, and citrus.  To simulate these
uses, standard scenarios associated with states of the highest US
planted acreage (based on the data provided in USDA National Agriculture
Statistics Service, “2002  Census of Agriculture, Volume 1 Chapter 2: 
U.S. State Level Data” at   HYPERLINK
http://www.nass.usda.gov/census/census02/volume1/us/index2.htm
http://www.nass.usda.gov/census/census02/volume1/us/index2.htm ) and the
highest exposure (driven in part by the vulnerability of the soils, the
climate, and the agricultural practices) as well as average exposure
were chosen for the selected crops.  Maximum application rates were
selected to model environmental concentrations for this screening-level
deterministic (risk quotient-based) assessment.  

The decision to use 15% of seasonal application rate (from the label)
rather than soil incorporation in the top 2 cm is based partly on the
limitations of the PRZM model capabilities.  PRZM cannot model both
surface and soil-incorporated granules simultaneously, and since the
greater threat is from surface runoff, it is more conservative to model
with surface-only application rather than a soil-incorporated-only
setting.  Indeed, when the models were run comparing both methods
(surface and soil-incorporated), EECs were slightly higher in the
surface-applied runs.  The same scenarios were also run using an
incorporation efficiency of 99% (only 1% left on surface) rather than
85%, to account for more efficient methods such as in-furrow
application.  Inputs for the model are shown in Table 8, and results are
tabulated in Table 9.  For a more detailed explanation and outputs from
this model, see Appendix D. 

Table 8.  PRZM/EXAMS input parameters  TC "Table 8.  PRZM/EXAMS input
parameters" \f E \l "1"  .

Parameter	Input*	Source/Rationale

Aerobic soil t1/2 (days)	55	Revised from 2001 Aldicarb RED; Upper 90th
pct bound on mean for combined parent+sulfoxide+sulfone half-life from
19 soils

Aerobic aquatic t1/2 (days) 	12	MRID 44592107. Single acceptable
guideline study for parent / sulfoxide / sulfone (4 days) x 3;
corresponds with DT90

Kd (L/kg)	0.12	Minimum non-sand value for aldicarb sulfone (MRID
43560302)

Incorporation Depth (inches)	0	Only granules left on surface considered:
15% of app. rate, to be consistent with terrestrial assessment

Seasonal application rate, citrus (lb a.i./Acre) – 15% unincorporated
0.7425	15% of label - maximum label application rate, 4.95 lb/A
(264-417)

Seasonal application rate, citrus (lb a.i./Acre) – 1% unincorporated
0.0495	1% of label - max. label application rate, 4.95 lb/A 

Application date, citrus	3/31	Best estimate, based on region and
cropping practices

Seasonal application rate, potatoes (lb a.i./Acre) – 15%
unincorporated	0.45	15% of label - max. application  rate, 3 lb/A
(264-417)

Seasonal application rate, potatoes (lb a.i./Acre) – 1% unincorporated
0.03	1% of label - max. application  rate, 3 lb/A 

Application date, potatoes	5/7	Best estimate, based on region and
cropping practices

Seasonal application rate, cotton (lb a.i./Acre) – 15% unincorporated
0.7425	15% of label - max. application  rate for two applications, 4.95
lb/A (264-330)

Seasonal application rate, cotton (lb a.i./Acre) – 1% unincorporated
0.0495	1% of label - max. application  rate for two applications, 4.95
lb/A

Application dates, cotton	4/13, 5/13	Best estimate, based on region and
cropping practices

Seasonal application rate, soybeans (lb a.i./Acre) – 15%
unincorporated	0.449	15% of label - max. application  rate

Seasonal application rate, soybeans (lb a.i./Acre) – 1% unincorporated
0.03	1% of label - max. application  rate

Application dates, soybeans	05/01	Best estimate, based on region and
cropping practices

Seasonal application rate, pecans (lb a.i./Acre) – 15% unincorporated
1.50	15% of label - max. application  rate,10 lb/A

Seasonal application rate, pecans (lb a.i./Acre) – 1% unincorporated
0.1	1% of label - max. application  rate,10 lb/A

Application dates, pecans	4/15	Best estimate, based on region and
cropping practices

* Parameters were selected in accordance with the Proposed Interim
Guidance for Input Values document, dated April 6, 2000.

Table 9.  Surface water EECs for aldicarb  TC "Table 9.  Surface water
EECs for aldicarb" \f E \l "1"  

Scenario

(application)	Peak concentration (ppb ai)	21-day concentration (ppb ai)
60-day concentration (ppb ai)

	Max Rate	Avg Rate	Max Rate	Avg Rate	Max Rate	Avg Rate

MS Cotton

(4.05 lbs ai/A) (1 app) = max	28.04	NA	26.56	NA	24.55	NA

MS Cotton

(4.95 lbs ai/A)total (2 apps) = max

(0.6 lbs ai/A) = avg	18.40	4.46	17.53	4.25	15.90	3.86

ID Potato

(3.0 lbs ai/A) = max

(2.7 lbs ai/A) = avg	1.43	1.28	1.40	1.26	1.35	1.22

FL Citrus

(4.95 lbs ai/A) = max

(3.7 lbs ai/A) = avg	2.96	2.27	2.80	2.15	2.50	1.92

MS Soybean

(3.0 lbs ai/A) = max

(0.7 lbs ai/A) = avg	7.12	1.66	6.76	1.58	6.05	1.41

GA Pecan

(10.05 lbs ai/A)= max

(3.1 lbs ai/A) = ave	12.04	3.71	11.40	3.51	10.19	3.14

max: maximum use rate on the label

ave: average use rate

Surface Water Impacts:  Available surface water monitoring data indicate
that impacts to fish and aquatic invertebrates as a result of aldicarb
(including the sulfone and sulfoxide products) are likely to be confined
to smaller (lower-order) streams in high use areas.  Widespread
contamination of surface water is not expected in larger (higher-order)
streams.  In NAWQA monitoring sites, aldicarb and its sulfone and
sulfoxide transformation products were detected infrequently (about 0.1
percent of all samples) at low concentrations (total residues <1.6 ppb).
 However, results of targeted monitoring in smaller streams suggest that
aldicarb may occasionally pose a contamination hazard.  For example,
Williams and Harris (1996) found substantially higher aldicarb
concentrations in small southeastern streams after a rainfall
(concentrations up to 430, 68, and 14 µg/l for aldicarb, aldicarb
sulfoxide, and aldicarb sulfone, respectively).  Risk quotients based on
concentrations measured in this study indicate a potential for risk to
fish and aquatic invertebrates in low order streams.

3.  	Terrestrial Organism Exposure Modeling  TC \l3 "3.  	Terrestrial
Organism Exposure Modeling 

Terrestrial wildlife exposure estimates are typically calculated for
birds and mammals, emphasizing a dietary exposure route for uptake of
the pesticide.  These exposures are considered surrogates for
terrestrial-phase amphibians as well as reptiles.  In the case of
aldicarb, which is applied only in a granular form, the method used in
calculating terrestrial EECs took into account this granular formulation
and its soil incorporation.  The model assumes that only 1% (in-furrow
application) or 15% (banded application) of the applied granules remain
on the surface and have the potential for terrestrial animal exposure. 
EECs were calculated based on application method, application rate, band
width (where appropriate), and percent incorporation of the granules
into the soil.  Terrestrial EECs were calculated using T-REX v 1.1
(2004) and are shown in Table 10.  Terrestrial EECs were calculated
using the following equations :

banded applications

 

broadcast applications

 

Table 10.  Terrestrial EECs for aldicarb, calculated based on
application method, application rate (maximum and average), and %
unincorporation of granules  TC "Table 10.  Terrestrial EECs for
aldicarb, calculated based on application method, application rate
(maximum and average), and % unincorporation of granules" \f E \l "1"  

Crop	Application method 	Application rate

(lbs ai/A)	% Unincorporated	EEC

(mg ai/ft2)

Max	Avg(c)

Max	Avg

Cotton

(single application)	Banded(a)

(4" band width)

(40" row spacing)	4.05	0.6	15	64.1	9.5

Dry Beans	Banded

(6" band width)

(48" row spacing)	2.1	1.0	15	26.3	12.5

Sorghum	In-furrow

(2" band width)

(36" row spacing)	1.05	0.4	1	1.9	0.7

Peanuts	Banded

(6" band width)

(36" row spacing)	3.0	0.9	15	28.1	8.4

Potatoes	Banded

(6" band width)

(38" row spacing) (d)	3.0	2.7	15	29.7	26.7

Soybeans	Banded

(6" band width)

(30" row spacing)	3.0	0.7	15	23.5	5.5

Sugar Beets

(single application)	Banded

(6" band width)

(22" row spacing)	4.95	1.8	15	28.4	9.7

Sweet Potatoes	Banded

(12" band width)

(48" row spacing)	3.0	1.4	1	1.3	0.6

Citrus	Broadcast(b)	4.95	3.7	15	7.7	5.8

Pecans	Broadcast	10.05	3.1	15	15.7	4.8

Ornamentals	Broadcast	5.0	NA	15	7.8	NA

(a)EEC = oz. ai per 1000 ft.* 28349 mg/oz  * % Unincorporated /
(bandwidth (ft) * 1000 ft) 

(b)EEC = [App. Rate (lbs ai/A) * (% pesticide left on surface) *
(453,590 mg/lb)] / [# rows/A * bandwidth * row length]

(c)Average application rate based on usage data

(d)Typical Irish potato row spacing from NSF Center for Integrated Pest
Management (www.ipmcenters.org)

B.  	Ecological Effects Characterization  TC \l2 "B.  	Ecological
Effects Characterization 

In screening-level ecological risk assessments, effects characterization
describes the types of effects a pesticide can produce in an organism or
plant.  This characterization is based on registrant-submitted studies
that describe acute and chronic toxicity information for various aquatic
and terrestrial animals and plants.  In addition, other sources of
information, including reviews of the open literature and the Ecological
Incident Information System (EIIS), are conducted to further refine the
characterization of potential ecological effects.  

Appendix C presents the results of the registrant-submitted toxicity
studies and open literature studies used to characterize effects for
this risk assessment.  In addition to the data submitted in support of
registration and the information compiled through the Agency pesticide
review process, the ECOTOX (ECOTOXicity) database was used to identify
additional data from the open literature.  Toxicity testing reported in
this section does not represent all species of birds, mammals, or
aquatic organisms.  Only a few surrogate species for both freshwater
fish and birds are used to represent all freshwater fish (2000+) and
bird (680+) species in the United States.  Mammalian acute studies are
usually limited to Norway or New Zealand rat or the house mouse. 
Estuarine/marine testing is usually limited to a crustacean, a mollusk,
and a fish.  Also, neither reptiles nor amphibians are tested.  The risk
assessment assumes that avian and reptilian toxicities are similar.  The
same assumption is used for fish and amphibians.

1.	Evaluation of Aquatic Ecotoxicity Studies  TC \l3 "1.	Evaluation of
Aquatic Ecotoxicity Studies 

a.	Toxicity to Freshwater Animals  TC \l4 "a.	Toxicity to Freshwater
Animals" 

Freshwater Fish, Acute

Aldicarb

Since the 96-h LC50 values ranged from 52 to 110 ppb ai, aldicarb is
categorized as very highly toxic to highly toxic to freshwater fish on
an acute basis (Table 11).  The most sensitive of these results was the
52 ppb ai for the bluegill sunfish (Mayer and Ellersieck 1986) conducted
under static conditions.  A supplemental acute toxicity test conducted
under static conditions reported a 96-h LC50 for aldicarb of 110 ppb ai
for juvenile bluegill sunfish.  Because of the static conditions, it is
likely this value reflects contribution of parent aldicarb and its
degradates. The bluegill sunfish 96-h LC50 of 52 ppb ai was chosen to
calculate acute risk quotients from exposure to aldicarb because it is
the most sensitive endpoint of the 96-h LC50 values.  There was an acute
value for fathead minnow exposed to aldicarb found in the public
literature but it was only for a 48 hour study, therefore it is likely
an underestimate of aldicarb toxicity to this species at 96 hours (i.e.
expect the 96-h LC50 value for this species to be <8860 ppb) and is
therefore classified as supplemental information.

Table 11.  Acute Toxicity Endpoints for Freshwater Fish  TC "Table 11. 
Acute Toxicity Endpoints for Freshwater Fish" \f E \l "1"  

Species	Endpoint (ppb ai)	MRID/Reference

Aldicarb

Bluegill sunfish	96-h LC50 = 52 ppb ai	MRID 40098001and MRID 3503 (Mayer
and Ellersieck 1986)

Rainbow trout	96-h LC50 = 560 ppb ai	MRID 40098001and MRID 3503 (Mayer
and Ellersieck 1986)

Fathead minnow	48-hr LC50 = 8,860 ppb ai	Moore. et al. 1998 
(Supplemental information as this is only a 48-h study)

Aldicarb sulfoxide

Rainbow trout	96-h LC50 = 7,140 ppb ai	MRID 45592115

Aldicarb sulfone

Rainbow trout	96-h LC50 = 42,000 ppb ai	Acc# 096727 (Anonymous 1976) 

Rainbow trout	96-h LC50 > 106,000 ppb ai	MRID 45592117

Aldicarb sulfoxide

A flow through acute toxicity test using the degradate aldicarb
sulfoxide was conducted on rainbow trout.  A 96-h LC50 of 7,140 ppb was
reported which is classified as moderately toxic (MRID 45592115).  

Aldicarb sulfone

An acute toxicity test conducted on rainbow trout using the degradate
aldicarb sulfone had a 96-h LC50 of 42,000 ppb ai.  This is
characterized as slightly toxic [Acc# 096727 (Anonymous 1976)].  A flow
through acute toxicity test using aldicarb sulfone had a 96-h LC50
greater than 106,000 ppb ai for rainbow trout, which is characterized as
practically non toxic (MRID 45592117).  

Based on the acute toxicity studies for freshwater fish, the relative
toxicity relationship is: aldicarb>aldicarb sulfoxide> aldicarb sulfone.

Freshwater Fish, Chronic

Aldicarb

A freshwater fish early life-stage test using aldicarb (99% ai) has been
conducted with the fathead minnow.  The NOAEC was 78 ppb ai and the
LOAEC was 156 ppb ai.  The most sensitive endpoint was the survival of
larvae-juveniles after 30-days exposure (MRID 44598601 also known as
BOWOAL07/4 (Q.H. Pickering and W.T. Gilliam 1982)).  However, according
to the acute freshwater fish data the bluegill sunfish was the most
sensitive freshwater fish tested with a 96-h LC50 of 52 ppb ai.  This
96-h LC50 of 52 ppb ai is lower than the NOAEC of 78 ppb ai for the
fathead minnow, indicating that the bluegill is much more sensitive to
aldicarb than the fathead minnow.  Therefore, a screening level chronic
RQ for fish cannot be calculated using the fathead minnow chronic NOAEC
directly.  However since both a supplemental acute (48-h LC50= 8,860 ppb
ai; Moore. et al., 1998) and acceptable chronic (NOAEC = 78 ppb ai)
aldicarb value exist for fathead minnow, an acute-to-chronic ratio (ACR)
can be calculated for this species and then used to determine an
estimated NOAEC for the bluegill sunfish.

The ACR for the fathead minnow of 114 is calculated by dividing the
fathead minnow 48-hr EC50 of 8,860 ppb ai by the fathead chronic NOAEC
of 78 ppb ai.  The 96-h LC50 of 52 ppb ai for the bluegill sunfish is
then divided by the ACR of 114 which results in an estimate of the
chronic NOAEC for the bluegill sunfish of 0.46 ppb ai.  A 48-h LC50
value was used to calculate the ACR rather than a 96-h LC50 because none
was available, this potentially over estimates the ACR for fathead
minnow.  Additionally, a robust estimate of an ACR (i.e. geometric mean
of ACRs for at least three fish species with one at least a coldwater
and a second a warmwater species) for aldicarb could not be calculated
because only one fish species, the fathead minnow, had both acute and
chronic endpoints available for determination of an ACR.  While a more
robust estimate of the ACR is desirable, the use of the fathead minnow
ACR is a reasonable estimate but may be either a slight over or
underestimate of ACR for fish.

Table 12.  Chronic Toxicity Endpoints for Freshwater Fish  TC "Table 12.
 Chronic Toxicity Endpoints for Freshwater Fish" \f E \l "1"  

Species	Endpoint	MRID/Reference

Aldicarb

Fathead minnow	fish early life stage NOAEC = 78 ppb ai	MRID 44598601
also known as BOWOAL07/4 (Q.H. Pickering and W.T. Gilliam 1982)

Bluegill sunfish	Estimated NOAEC  = 0.46 ppb ai	96-h LC50 for bluegill
sunfish (52 ppb ai) divided by ACR (fathead minnow 48-h EC50 of 8860 ppb
ai divided by NOAEC of 78 ppb ai)

Freshwater Invertebrates, Acute

Aldicarb

A Daphnia magna core study determined the 48-h EC50 to be 410 ppb ai
(Acc #096683, also known as BOWOAL08 and MRID 107395 (Vilkas 1977),
categorizing aldicarb as highly toxic to aquatic freshwater
invertebrates on an acute basis.  Because this test was conducted under
static rather than flow-through conditions, it is likely that this value
reflects the contributions of a mixture of parent aldicarb and various
degradates.  A supplemental study from the literature reported the 48-h
LC50 of aldicarb to Daphnia magna, Aedes aegypti, Atermia sp., and Aedes
taeniorhynchus as 75, 290, 5460, and 150 ppb ai respectively, in 48 hour
static tests (Song et al., 1997).  A supplemental study from open
literature also concluded that aldicarb was very-highly toxic to Daphnia
magna with a reported 48-h EC50 of 583 ppb (Moore. et al. 1998).  This
same study reported a 48-h EC50 of 3990 ppb for Hyalella azteca
(categorized as moderately toxic) and a reported 48-h EC50 of 20 ppb for
Chironomus tentans.  A supplemental study obtained from open literature
(Foran et al. 1985) determined the 48-h EC50 of juvenile Daphnia laevis
to be 65 ppb and 51 ppb for adult Daphnia laevis categorizing aldicarb
as very highly toxic. 

Because Moore et al. (1998) is classified as a supplemental study of
high quality, the 48-h Chironomus tentans EC50 value of 20 ppb will be
used in the risk characterization. 

Aldicarb sulfoxide

Foran et al. 1985 also found that aldicarb sulfoxide is also very highly
toxic to Daphnia laevis, with a 48-h EC50 of 57 ppb for juveniles and 43
ppb for adults.  Thus, aldicarb sulfoxide toxicity to freshwater
invertebrates appears to be similar in toxicity to aldicarb.  A
supplemental static acute toxicity test was performed using the
degradate aldicarb sulfoxide with the test species Daphnia magna.  The
48-h EC50 was 696 ppb, which is classified as highly toxic to daphnids
[MRID 45592114].  

Aldicarb sulfone

Based on a core study, the 48-h EC50 for aldicarb sulfone is 280 ppb for
Daphnia magna which is categorized as highly toxic to freshwater
invertebrates on an acute basis  [Acc# 096727 (Anonymous 1976) ].  Foran
et al. (1985) also found that the toxicity of aldicarb sulfone to
daphnids is in the highly toxic category (juvenile 48-h EC50=556 ppb and
adult 48-h EC50=369 ppb).  

 aldicarb sulfoxide > aldicarb sulfone.

Table 13.  Acute Toxicity Endpoints for Freshwater Invertebrates  TC
"Table 13.  Acute Toxicity Endpoints for Freshwater Invertebrates" \f E
\l "1"  

Species	Endpoint	MRID/Reference

Aldicarb

Daphnia magna	48-h EC50 = 410 ppb	Acc #096683, also known as BOWOAL08
and MRID 107395 (Vilkas 1977),

Daphnia magna	48-hr LC50 = 75 ppb	Song et al., 1997

Aedes aegypti	48-hr LC50 = 290 ppb	Song et al., 1997

Atermia sp.	48-hr LC50 = 5460 ppb	Song et al., 1997

Aedes taeniorhynchus	48-hr LC50 = 150 ppb	Song et al., 1997

Daphnia magna	48-hr EC50 = 583 ppb 	Moore. et al. 1998

Hyalella azteca	48-hour EC50 = 3990 ppb	Moore. et al. 1998

Chironomus tentans	48-hour EC50 = 20 ppb	Moore. et al. 1998

Daphnia laevis (juvenile)	48 hr EC50 =65 ppb	Foran et al. 1985

Daphnia laevis (adult)	48 hr EC50 = 51 ppb	Foran et al. 1985

Aldicarb sulfoxide

Daphnia magna	48-h EC50 = 696 ppb	MRID 45592114

Daphnia laevis (adult)	48 hr EC50 =  43 ppb	Foran et al. 1985

Daphnia laevis (juvenile)	48 hr EC50 =57 ppb	Foran et al. 1985

Aldicarb sulfone

Daphnia magna	48-h EC50 = 280 ppb	Acc# 096727 (Anonymous 1976) 

Daphnia laevis (adult)	48-h EC50=369 ppb	Foran et al. (1985)

Daphnia laevis (juvenile)	48-h EC50=556 ppb	Foran et al. (1985)

Qualitative Studies

Midge, Chironomus riparius	Symptoms of intoxication	Kallander et al.
1997

Midge, Chironomus riparius	24-hr LC50  (water only) =  9.9 ppb

24-hr LC50 (spiked water) = 10.0 ppb, 

24-hr LC50 (spiked sediment) = 26.7 ppb	Lydy et al. 1990

Gammarus italicus Goedm. 	96-hr LC50 = 420 ppb	Pantani et al. 1997

Echinogammarus tibaldii Pink.	96-hr LC50 = 220 ppb 	Pantani et al. 1997

Midge Chironomus riparius	24 hr EC50 value = 23 ppb 	Sturm and Hansen
1999

Daphnid  Daphnia magna	24 hr EC50 value = 227.6 ppb 	Sturm and Hansen
1999

Aedes taeniorhynchus	48-hr LC50 = 150 ppb  (hyperosmotic condition)

72-hr LC50=200 ppb ( isosmotic conditions)	Song and Brown 1998

Artemia sp.	48-hr LC50 = 5460 ppb ( hyperosmotic)

72-hr LC50=17250 ppb (isosmotic conditions)	Song and Brown 1998

Pond snail Lymnaea acuminata	48-hr LC50 = 20000 ppb	Singh and Agarwal
1981

Apple snail Pila globosa Swainson	48-hour LC50 value could not be
determined	Singh and Agarwal 1981

Midge Chironomus riparius	None	Fisher et al. 1993

Midge Chironomus riparius	24-hour LC50 values ranged from 17-28 ppb  at
pH 4-8	Suorsa and Fisher 1986

Aldicarb sulfoxide

Daphnia magna	EC50 = 696 ppb	MRID 45592114

Daphnia laevis (adult)	48 hr EC50 =  43 ppb	Foran et al. 1985

Daphnia laevis (juvenile)	48 hr EC50 =57 ppb	Foran et al. 1985

Aldicarb sulfone

Daphnia magna	EC50 = 280 ppb	Acc# 096727 (Anonymous 1976) 

Daphnia laevis (adult)	EC50=369 ppb	Foran et al. (1985)

Daphnia laevis (juvenile)	EC50=556 ppb	Foran et al. (1985)

Freshwater Invertebrate Qualitative Studies

Using the database ECOTOX to identify additional data from the open
literature, several supplemental studies were identified that can be
used qualitatively to discuss the effects of aldicarb on freshwater
invertebrates.  These studies were not appropriate for quantitative use
in calculation of risk quotients (see Appendix L for more detailed
explanations).

A one day test identified aldicarb as very highly toxic to the midge and
daphnid on an acute toxicity basis under static conditions.  The 24-h
EC50 value was reported to be 23 ppb a.i. for the midge and 227.6 ppb
a.i. for the daphnid (Sturm and Hansen 1999).  

Several studies examined the effects of aldicarb to freshwater
invertebrates and the effects of pulse dosing, pH, and different modes
of exposure.  In a pulsed exposure test, Kallander et al. (1996) studied
midges (Chironomus riparus) exposed to aldicarb under static conditions.
 Midges exposed to aldicarb for two, pulsed 1-hour periods with a
recovery period in clean water for 6 or more hours showed significantly
fewer symptoms of intoxication than those exposed continuously for 2
hours.  This indicates that continuous exposure to aldicarb from runoff
events with no recovery time would exacerbate the symptoms of
intoxication for freshwater invertebrates.

The 24 hour acute toxicity of aldicarb to Chironomus riparus was studied
under static conditions at pH 4, 6, and 8 (Suorsa and Fisher 1986).  The
24-h LC50 values ranged from 17-28 ppb for aldicarb at pH 4-8.  
Toxicity of aldicarb to midges did not differ significantly as a
function of pH. 

A 24 hour static study by Lydy et al (1990) evaluated three modes of
exposure of aldicarb to Chironomus riparius: treated water only with no
sediment (water only); treated water with untreated sediment (spiked
water); and treated sediment with untreated water (spiked sediment). 
The reported 24-h LC50 for the water only, spiked water, and spiked
sediment treatments were 9.9, 10.0 and 26.7 ppb respectively, which
classifies aldicarb as very highly toxic to C. riparius on an acute
toxicity basis for all three routes of exposure.  In addition, these
tests indicate that the water exposure pathways produce more sensitive
endpoints than sediment exposure.  This affirms the use of acute aquatic
toxicity tests using aldicarb for freshwater invertebrates to be the
most sensitive route of exposure.

Fisher et al. 1993 studied the toxicity of aldicarb to the midge with
and without sediment.  Five molecular descriptors (molecular volume,
Henry’s law constant, n-octanol/water partition coefficient, molecular
connectivity, and linear solvation energy) were used in regression
analysis as potential predictors of pesticide activity.  Quantitative
structure activity relationships indicate sediment sorption plays a
large role in the ultimate toxicity of aldicarb to the midge.  

Several studies were identified that deal with species not normally
tested in registrant submitted studies. These studies classified
aldicarb in a range of slightly toxic to highly toxic.  The 96-hr acute
toxicity of aldicarb to Gammarus italicus Goedm and Echinogammarus
tibaldii Pink was studied under static conditions (Pantani et al. 
1997).  The 96-h LC50 value was determined to be 420 ppb a.i. and 220
ppb a.i., respectively, which categorizes aldicarb as highly toxic on an
acute toxicity basis.

The 240-h acute toxicity of Aldicarb to the pond snail Lymnaea acuminata
and the apple snail Pila globosa Swainson was studied under static
conditions (Singh and Agarwal 1981).  Paralysis was observed in the test
organisms within 24 hours of exposure even though the animals remained
alive for varying lengths of time; no mortality was observed in the
control group.  The 48-h LC50 value was 20000 ppb a.i., which
categorizes aldicarb as slightly toxic to L. acuminata on an acute
toxicity basis.  The 48-h LC50 value could not be determined for the
apple snail within the range of doses tested.  The LC50 values from 72
hours to 240 hours ranged from 210000-78000 ppb, which categorizes
aldicarb as practically non-toxic to slightly toxic to P. globosa on an
acute to subchronic toxicity basis.

The 48-h hyperosmotic and 72-hour isosmotic acute toxicities of Aldicarb
to the mosquito Aedes taeniorhynchus and brine shrimp Artemia sp. were
studied under static conditions (Song and Brown 1997). Mosquito and
nauplii larvae were exposed to the test material at two different
salinities, hyperosmotic and isosmotic.  Under hyperosmotic conditions,
the reported Aedes  48-hour LC50 was 150 ppb a.i and the Artemia 48-hour
LC50 was 5460 ppb a.i. Aldicarb is thus, classified as highly toxic to
Aedes and moderately toxic to Artemia sp.  Under isosmotic conditions,
the reported 72-hour LC50 was 200 ppb a.i. for Aedes (highly toxic) and
the 72-hour LC50 was 17250 ppb a.i. for Artemia (slightly toxic).

Freshwater Invertebrate, Chronic

Aldicarb

The chronic risk to freshwater invertebrates is based on the
estuarine/marine chronic study using Mysidopsis bahia.  The reason for
using this endpoint is based on the memorandum dated December 14, 1993,
from A. Maciorowski, EFED to P. Poli, SRRD (D196663): “EEB has
previously received and reviewed a valid Mysid shrimp chronic toxicity
study that resulted in a calculated MATC of 1-1.5 ppb. Since the acute
data indicates that the Mysid shrimp is more sensitive to aldicarb than
Daphnia magna (Mysid shrimp LC50 = 16 ppb, Daphnia magna LC50 = 410.7
ppb) and EEB does have valid Mysid shrimp chronic toxicity data, EEB is
willing to waive the requirement for the Guideline 72-4(b) Freshwater
Invertebrate Life Cycle Study. However, as a result all aquatic risk
assessments utilizing invertebrate chronic toxicity data will be based
on the Mysid shrimp data.”  The mysid shrimp NOAEC equals 1.0 ppb.

A supplemental chronic toxicity study was submitted that evaluated the
effect of aldicarb (99.9% a.i.) on Daphnia magna.  An EC50 of 90 ppb,
NOAEC of 20 ppb, and LOAEC of 60 ppb were reported for mortality and
immobilization.  An EC50 with a range of 190 to 570 ppb, NOAEC of 190
ppb and LOAEC greater than 190 ppb were reported for reproductive
effects.  The most sensitive endpoint was reproductive effects [MRID
45592112]. This study is classified as supplemental and is not
upgradeable to core due to the study’s deviations.  Therefore, the
aquatic risk assessment will utilize the mysid shrimp data (NOAEC = 1.0
ppb)

Table 14.  Chronic Toxicity Endpoints for Freshwater Invertebrates  TC
"Table 14.  Chronic Toxicity Endpoints for Freshwater Invertebrates" \f
E \l "1"   

Species	Endpoint	MRID/Reference

Aldicarb

Mysidopsis bahia	NOAEC = 1 ppb	MRID 00066341(U.S. EPA 1981b)

Daphnia magna	NOAEC = 20 ppb	MRID 45592112

b.	Toxicity to Estuarine and Marine Animals  TC \l4 "b.	Toxicity to
Estuarine and Marine Animals 

Estuarine and Marine Fish, Acute

Aldicarb

Based on results from the preferred test species, sheepshead minnow,
96-h LC50 values range from 41 to 170 ppb. Therefore, aldicarb is
categorized very highly to highly toxic to estuarine/marine fish on an
acute basis.  The most sensitive estuarine/marine fish species tested
was the sheepshead minnow with a 96-h LC50 of 41 ppb [MRID 40228401
(U.S. EPA 1986)].  A supplemental study obtained from open literature
(Landau and Tucker 1984) found a similar magnitude value for a snook
(Centropomus undecimalis) embryo/larva bioassays with a 36-hr LC50 of 40
ppb. After 96-hr of exposure the snook should have an even lower LC50;
therefore, the snook is more sensitive than the sheepshead minnow.

Table 15.  Acute Toxicity Endpoints for Estuarine and Marine Fish  TC
"Table 15.  Acute Toxicity Endpoints for Estuarine and Marine Fish" \f E
\l "1"  

Species	Endpoint	MRID/Reference

Aldicarb

Sheepshead minnow	96-h LC50 = 41 ppb	MRID 40228401 (U.S. EPA 1986)

Snook (Centropomus undecimalis)	36-h LC50 = 40 ppb	Landau and Tucker
1984

Sheepshead minnow (Cyprinodin variegates)	96-h  LC50 = 170 ppb	MRID
40228401 (U.S. EPA 1986)

Estuarine and Marine Fish, Chronic

Aldicarb

A chronic estuarine/marine fish early life-stage test using aldicarb
(99% ai) has been conducted with the sheepshead minnow.  The NOAEC was
50 ppb and the LOAEC was 88 ppb.  The most sensitive endpoint was growth
based on the mean standard length [MRID 00066341 (U.S. EPA 1981b)]. The
lowest chronic endpoint value available for sheephead minnow is higher
than the lowest acute endpoint value for sheepshead minnow.  Therefore,
it not appropriate to screen for chronic risks to estuarine/marine fish
with this value.  However, since there is an ACR of 114 available for
fish (freshwater fathead minnow ACR, see the Freshwater Fish, Chronic
Aldicarb section above) this value was used to estimate a chronic NOAEC
using the acute 96-h LC50 for sheepshead minnow from MRID 40228401.

The estimated chronic NOAEC for the sheepshead minnow is 0.36 ppb and is
calculated by dividing the 96-h LC50 of 41 ppb for the sheepshead minnow
by the ACR for fathead minnow of 114.  As discussed in the Freshwater
Fish, Chronic Aldicarb section above a 48-h LC50 value was used to
calculate the ACR rather than a 96-h LC50 because none was available,
this potentially over estimates the ACR for fathead minnow. 
Additionally, a robust estimate of an ACR (i.e. geometric mean of ACRs
for at least three fish species with one at least a coldwater and a
second a warmwater species and one a saltwater species) for aldicarb
could not be calculated because only one fish species, the fathead
minnow, had both acute and chronic acceptable endpoints available for
determination of an ACR.  While a more robust estimate of the ACR is
desirable, the use of the fathead minnow ACR is a reasonable estimate
but may be either a slight over or underestimate of ACR for fish. 

Table 16.  Chronic Toxicity Endpoints for Estuarine and Marine Fish  TC
"Table 16.  Chronic Toxicity Endpoints for Estuarine and Marine Fish" \f
E \l "1"  

Species	Endpoint (NOAEC)	MRID/Reference

Aldicarb

Sheepshead minnow	Early life stage NOAEC = 50 ppb 	MRID 00066341 (U.S.
EPA 1981b)

Sheepshead minnow	Estimated NOAEC = 0.36 ppb 	96-h LC50 for sheepshead
minnow (41 ppb ai) divided by ACR (fathead minnow 48-h EC50 of 8860 ppb
ai divided by NOAEC of 78 ppb ai)

Estuarine and Marine Invertebrates, Acute

Aldicarb

Based on results from the preferred test species, pink shrimp and
Eastern oyster, following test guidelines, the toxicity values fall in
the range of 12 to 8800 ppb.  Therefore, aldicarb is categorized as very
highly to moderately toxic to estuarine/marine invertebrates on an acute
basis.  The 48-h EC50 for the Eastern oyster is reported as 8800 ppb. 
Therefore, the most sensitive estuarine/marine invertebrate tested was
the pink shrimp, with a 96-h LC50 of 12 ppb [MRID 40228401 (U.S. EPA
1986)].

Table 17.  Acute Toxicity Endpoints for Estuarine and Marine
Invertebrates  TC "Table 17.  Acute Toxicity Endpoints for Estuarine and
Marine Invertebrates" \f E \l "1"  

Species	Endpoint	MRID/Reference

Aldicarb

Eastern oyster	48-h EC50 = 8800 ppb	MRID 40228401 (U.S. EPA 1986)

Pink shrimp	96-h LC50 = 12 ppb	MRID 40228401 (U.S. EPA 1986)

Estuarine and Marine Invertebrate, Chronic

Aldicarb

A chronic estuarine/marine invertebrate full life-cycle test using
aldicarb (99% ai) has been conducted with the mysid shrimp. The NOAEC
was 1 ppb and the LOAEC was 1.5 ppb.  The most sensitive endpoint was
average number of offspring [MRID 00066341(U.S. EPA 1981b)].

Table 18.  Chronic Toxicity Endpoints for Estuarine and Marine
Invertebrates  TC "Table 18.  Chronic Toxicity Endpoints for Estuarine
and Marine Invertebrates" \f E \l "1"   

Species	Endpoint	MRID/Reference

Aldicarb

Mysid shrimp	Full life cycle NOAEC = 1 ppb	MRID 00066341(U.S. EPA 1981b)

c.	Toxicity to Aquatic Plants  TC \l4 "c.	Toxicity to Aquatic Plants 

Aldicarb

According to CFR 40 Part 158.540, aquatic plant testing is generally not
required for non-herbicides unless there is evidence of potential
phytotoxicity at use rates from other lines of evidence. The most recent
TEMIK® label (EPA Reg. No.264-330) states that “treatments in excess
of 7 [and 5] pounds per acre made directly in the seed furrow may delay
plant emergence and reduce plant stand”.  Because of potential effects
to plants, EFED requests that Tier I studies should be conducted.  

At this time, EFED does have one study conducted on the marine diatom,
Skeletonema costatum [MRID No.40228401 (U.S. EPA 1986)].  The EC50 is
>50000 ppb.  This EC50 value is greater than the modeled peak, 21 day,
and 60 day EEC values for cotton of 18.40, 17.53, and 15.90 ppb,
respectively.  The EC50 value is also greater than the monitoring peak
value of 454 ppb.

Table 19.  Toxicity Endpoints for Aquatic Plants  TC "Table 19. 
Toxicity Endpoints for Aquatic Plants" \f E \l "1"  

Species	Endpoint	MRID/Reference

Aldicarb

Marine diatom, Skeletonema costatum	EC50  > 50000 ppb	MRID No. 40228401
(U.S. EPA 1986)

	Evaluation of Terrestrial Ecotoxicity Studies  TC \l3 "2.	Evaluation of
Terrestrial Ecotoxicity Studies 

	Toxicity to Terrestrial Animals  TC \l4 "a.	Toxicity to Terrestrial
Animals 

Birds, Acute and Subacute

The acute oral LD50 is 1.0 mg/kg-bw for aldicarb, and 33.5 mg/kg-bw for
aldicarb sulfone.  The most sensitive species tested for both aldicarb
and aldicarb sulfone is the mallard duck.  Aldicarb and aldicarb sulfone
are categorized as very highly toxic and highly toxic to avian species
on an acute oral basis, respectively (MRID 107398).

The most sensitive species tested on a subacute 5-d dietary basis for
both aldicarb and aldicarb sulfone is the bobwhite quail.  The 5-d LC50
is 71 ppm for aldicarb, and 5706 ppm for aldicarb sulfone (or
sulfocarb).  Aldicarb and aldicarb sulfone are categorized as very
highly toxic and practically nontoxic to avian species, respectively
(MRID: 00102132; 1096727).

Birds, Chronic 

No avian reproduction studies were submitted by the registrant.  Avian
reproduction studies on the mallard duck and bobwhite quail using the
TGAI are required for aldicarb because the following conditions are met:
(1) birds may be subject to repeated or continuous exposure to the
pesticide, especially preceding or during the breeding season, and (2)
the pesticide is stable in the environment to the extent that
potentially toxic amounts may persist in animal feed.

Mammals, Acute

Rat toxicity values obtained from the Agency's Health Effects Division
(HED) substitute for wild mammal testing.  Aldicarb is categorized as
very highly toxic to small mammals on an acute oral basis with a rat
LD50 of 0.9 mg/kg-bw (MRID 00057333).

Mammals, Chronic

In a 2-generation reproduction study (MRID 42148401), rats were exposed
to aldicarb in their diet at concentrations of 0, 2, 5, 10, and 20 ppm. 
Exposure consistently led to decreased dam body weight gain (parental
LOAEL = 0.7 - 0.9 mg/kg-bw; NOAEL = 0.4 mg/kg-bw).  Aldicarb treatment
also caused lower survivability and pup weights in offspring of all
litters (reproductive LOAEL = 1.4 - 1.7 mg/kg-bw; NOAEL = 0.7 - 0.9
mg/kg-bw).  These toxicity values are similar to the acute oral LD50
mammalian values and suggest that mammals that survive acute aldicarb
exposure may suffer adverse reproductive effects from chronic exposure.

Beneficial Insects

A honey bee acute contact study using the TGAI is not required for
aldicarb due to its granular formulation.  However, aldicarb is
categorized highly toxic to bees on an acute contact basis with an LD50
of 0.285 g/bee (MRID 00036935).  It is recognized that potential
honeybee exposure may occur due to the systemic nature of aldicarb. 
Because of its granular formulation, it is unlikely that there is a
direct contact exposure scenario for honeybees; however, these and other
beneficial insects could be exposed to aldicarb and aldicarb residues
through contact with plants and soil.  

Earthworms

Soil-dwelling invertebrates, such as earthworms, can play important
roles in maintaining soil fertility and facilitating organic matter
degradation, as well as an important food source for birds and mammals. 
A study by Mosleh et al (2003) demonstrated an earthworm (Aporrectodea
caliginosa) 28-day LC50 of 0.68 ppm.  

	Toxicity to Terrestrial Plants  TC \l4 "b.	Toxicity to Terrestrial
Plants 

Terrestrial plant testing is required for pesticides other than
herbicides if data from the literature indicate that a pesticide is
phytotoxic.  The most recent TEMIK® label (EPA Reg. No.264-330) states
that “treatments in excess of 7 [and 5] pounds per acre made directly
in the seed furrow may delay plant emergence and reduce plant stand”. 
Because of potential effects to plants, EFED requests that Tier I
studies should be conducted.

Terrestrial plant exposure characterization is calculated using OPP’s
TerrPlant model.  Exposure calculations are based on a pesticide’s
water solubility and the amount of pesticide present on the soil surface
within the first inch of depth.  For granular pesticides, only seedling
emergence toxicity endpoints are used for RQ calculations, and exposure
is modeled using TerrPlant assuming a no-drift scenario.

Palaniswamy et al (1974) examined the effects of aldicarb on germination
of okra and results indicated no adverse effects on seed germination in
aldicarb-treated seeds up to a concentration of 1.32 lbs ai/A.  Because
no effects were seen with this study, the results could not be used to
calculate terrestrial plant risk.

Ellis et al (1986) studied rye seedling emergence following aldicarb
application and found significant reduction in emergence in all
treatment groups (17.6 - 176 lbs ai/A).  A second test was performed
with aldicarb concentrations ranging from 0.5 - 17.6 lb ai/A, and no
effects were seen at any of the dose levels.  Because no effects were
seen with this study, the results could not be used to calculate
terrestrial plant risk.

Table 20 summarizes the most sensitive ecological toxicity endpoints for
aquatic and terrestrial organisms.  Discussions of the effects of
aldicarb on aquatic and terrestrial taxonomic groups are presented
below.

Table 20.   Toxicity Endpoints Used in the Risk Assessment  TC "Table
20.   Toxicity Endpoints Used in the Risk Assessment" \f E \l "1"  

Toxicity Test/Species	Toxicity Endpoint	MRID Number/References

Avian acute oral/  Mallard duck	 LD50 = 1.0 mg/kg

g/bee	MRID #00036935

Terrestrial Plants	N/A	N/A

Fish (freshwater) acute/ Bluegill sunfish	LC50 = 52 ppb

	MRID # 400098001 and MRID 3503

Fish (freshwater) chronic/Bluegill sunfish	ENEC = 0.46 ppb 	Extrapolated
from fathead minnow study (MRID # 44598601)

Fish (estuarine) acute/ Sheepshead minnow		LC50 = 41 ppb	MRID # 40228401

Fish (estuarine) chronic/Sheepshead minnow	ENEC = 0.36 ppb	Extrapolated
from fathead minnow study (MRID #44598601)

Invertebrate (freshwater) acute/Chironomus tetans	EC50 = 20 ppb	Moore et
al., 1998

Invertebrate (freshwater) chronic/ Mysid shrimp	NOAEC = 1.0 ppb	MRID #
00066341

Invertebrate (estuarine) acute/Pink shrimp	LC50 = 12 ppb	MRID # 40228401

Invertebrate (estuarine) chronic/ Mysid shrimp	NOAEC = 1.0 ppb	MRID #
00066341

Aquatic plants/ Marine diatom			EC50 > 50000 ppb	MRID # 40228401

	Terrestrial Behavioral Studies  TC \l3 "3.	Terrestrial Behavioral
Studies 

Several studies from the open literature provide information on the
effects of aldicarb exposure on terrestrial animal behavior.  A field
study by Hawkes et al. (1996) demonstrated reduced cover-seeking in
mourning doves and bobwhite quail following exposure to a lethal
aldicarb dose.  Birds in the study became immobolized before they were
able to seek cover.  Palumbo et al. (2001) showed that rats exposed to
low levels of aldicarb (10 and 100 ppb) demonstrated decreased motor
activity and exploration and  improved water maze performance.  This
study, although preliminary, suggests that rats exposed to aldicarb may
have changes in learning and motor behavior.

4.	Use of the Probit Slope Response Relationship  TC \l3 "4.	Use of the
Probit Slope Response Relationship 

The Agency uses the probit dose response relationship as a tool for
providing additional information on the listed animal species acute
levels of concern (LOC).  The acute listed species LOCs of 0.1 and 0.05
are used for terrestrial and aquatic animals, respectively.  As part of
the risk characterization, an interpretation of acute LOCs for listed
species is discussed.  This interpretation is presented in terms of the
chance of an individual event (i.e., mortality or immobilization) should
exposure at the estimated environmental concentration actually occur for
a species with sensitivity to aldicarb on par with the acute toxicity
endpoint selected for RQ calculation.  To accomplish this
interpretation, the Agency uses the slope of the dose response
relationship available from the toxicity study used to establish the
acute toxicity measurement endpoints for each taxonomic group.  The
individual effects probability associated with the LOCs is based on the
mean estimate of the  slope and an assumption of a probit dose response
relationship.  In addition to a single effects probability estimate
based on the mean, upper and lower estimates of the effects probability
are also provided to account for variance in the slope.  The upper and
lower bounds of the effects probability are based on available
information on the 95% confidence interval of the slope.  A statement
regarding the confidence in the applicability of the assumed probit dose
response relationship for predicting individual event probabilities is
also included.  Studies with good probit fit characteristics (i.e.,
statistically appropriate for the data set) are associated with a high
degree of confidence. Conversely, a low degree of confidence is
associated with data from studies that do not statistically support a
probit dose response relationship.  In addition, confidence in the data
set may be reduced by high variance in the slope (i.e., large 95%
confidence intervals), despite good probit fit characteristics.

Individual effect probabilities are calculated based on an Excel
spreadsheet tool IECV1.1 (Individual Effect Chance Model Version 1.1)
developed by the U.S. EPA, OPP, Environmental Fate and Effects Division
(June 22, 2004).  The model allows for such calculations by entering the
mean slope estimate (and the 95% confidence bounds of that estimate) as
the slope parameter for the spreadsheet.  In addition, the LOC (0.1 for
terrestrial animals and 0.05 for aquatic animals) is entered as the
desired threshold. 

	Incident Data Review  

.   TC \l3 "5.	Incident Data Review 

There have been 29 incidents related to aldicarb reported in the
Environmental Incident Information System (EIIS) database (reported to
the Agency from 1988 to 2005).   Of these 29 incidents, 16 were from
misuse (accidental or intentional), 11 were of undetermined use, and 2
were registered agricultural uses.  Approximately 17 of the 29 incidents
reported included bird kills. Fourteen bird kill incidents were from
intentional misuse, and 3 were of undetermined use.  Eight incidents
resulted in mammal kills (all misuse or undetermined use). The presence
of aldicarb in the tissue residue analysis was confirmed on 4 of the 17
bird kill incidents and 2 of the 8 mammal kill incidents.  Two aquatic
incidents in North Carolina involving fish kills were reported, one as a
result of registered use and one of undetermined use.  The remaining 6
incidents reported to the database involved deleterious effects on
agricultural plant species (cotton, peanuts, and potatoes) resulting
from undetermined aldicarb exposure.  Of these 6 plant incidents, only
one could be conclusively attributed to aldicarb use; the other
incidents involved the application of several chemicals, including
aldicarb.

Currently, no systematic or reliable mechanism exists for the accurate
monitoring and reporting of wildlife kill incidents to the Agency. 
Moreover, before a pesticide incident can be reported or investigated,
the dead animals must first be found.  In the absence of monitoring
following pesticide applications, kills are not likely to be noticed in
agro-environments which are generally away from human activity. Even if
onlookers are present, dead wildlife species, particularly small song
birds and mammals, are easily overlooked, even by experienced and highly
motivated observers. Even in sparse vegetative cover, wildlife carcass
detection is difficult and as vegetative cover increases the difficulty
in detection is exacerbated.  Under some circumstances intoxicated
animals may seek heavy cover before dying which decreases the
probability of detection further. Poisoned birds may fly from the sites,
succumbing outside of the area or scavengers may remove carcasses before
they can be observed, significantly reducing the chance of detection. 

Balcomb (1986) reported that songbird carcasses removal rate ranged from
62 to 92 percent in the first 24 hours following placement, with a mean
loss at 24 hours of 75% (S.D. = 12.4). Overall, by the end of the 5-day
monitoring period, 72 of the 78 carcasses had been removed by
scavengers. In addition, the number of birds per acre alone, not
considering these other factors, makes detection of kills difficult.
Best (1990) reported from 0.57 live birds per acre in the center to 2.8
live birds per acres in the perimeter of corn fields in Iowa and
Illinois. Even if all the birds in a field were killed and remained on
the field, the probability of  observing carcasses, particularly when
not systematically searching,  at these densities, is not high. Research
has shown that even when intense systematic searches are conducted by
highly trained individuals for placed carcasses in agro-environments,
recovery rates rarely exceed 50 percent (Madrigal et al.1996).

Even if dead animals are observed, they might not be reported to the
Agency. Persons unfamiliar with the toxicity of pesticides to non-target
species may fail to associate the finding with the pesticide
application, especially if the two events are separated by several days
and only a few birds are observed dead.  Even if the association is
made, the observer must be aware or have the motivation to find out
where to report the incident. Therefore, the reporting of a few dead
birds associated with the use of a chemical is believed to provide
evidence that substantial effects may be occurring.

European Incidents:	Data from Europe indicate that some wildlife
mortality incidents are attributed to the use of aldicarb, although it
is not known how well the associated uses correspond with conditions in
the United States.  The Aldicarb Terrestrial Risk Assessment for the
Position Document 1 (23 September 1991) (PD1) cites incidents occurring
in Germany where >600 birds were killed in 1977 by aldicarb use on sugar
beets, and 7 incidents occurring in Great Britain during 1975-76 which
killed >200 birds.  In Great Britain, Greig-Smith (1987) reports one
bird kill incident attributed to aldicarb occurring between the years
1980 and 1987, and Greig-Smith et al. (1989) reported an additional
incident in which two partridges died in a sugar beet field after
aldicarb was applied with poor incorporation into the soil.

It is important to note there are differences between the reporting of
incidences and wildlife kills in Europe and the United States. 
Reporting of wildlife kills is voluntary in the United States. 
Therefore, if someone observes bird or mammal carcasses near a field, it
is a voluntary effort to report this incident to the appropriate
authorities.  In the United Kingdom, the process is mandatory and
incidences and wildlife kills are more frequently reported.  In
addition, there are many birding clubs in the U.K. that regularly report
incidences. A study by Mineau et al. 1999 studied the poisoning of
raptors by pesticides with emphasis on Canada, U.S. and the U.K. A high
proportion of reported cases in the U.K. resulted from abuse uses of
pesticides (willful poisoning) compared to a very low proportion
occurring in North America (U.S. plus Canadian incidences).

	RISK CHARACTERIZATION  TC \l1 "IV.	RISK CHARACTERIZATION 

Risk characterization is the integration of exposure and effects
characterization to determine the ecological risk from the use of
aldicarb and the likelihood of effects on aquatic life, wildlife, and
plants based on varying pesticide-use scenarios.  The risk
characterization provides an estimation and a description of the risk;
articulates risk assessment assumptions, limitations, and uncertainties;
synthesizes an overall conclusion; and provides the risk managers with
information to make regulatory decisions.

	Risk Estimation - Integration of Exposure and Effects Data  TC \l2 "A.
Risk Estimation - Integration of Exposure and Effects Data 

Results of the exposure and toxicity effects data are used to evaluate
the likelihood of adverse ecological effects on non-target species.  For
the assessment of aldicarb risk, the risk quotient (RQ) method is used
to compare exposure and measured toxicity values.  Estimated
environmental concentrations (EECs) are divided by acute and chronic
toxicity values.  The RQs are compared to the Agency’s levels of
concern (LOCs).  These LOCs are the Agency’s interpretive policy and
are used to analyze potential risk to non-target organisms and assess
the need to consider regulatory action.  These criteria are used to
indicate when a pesticide’s directed label use has the potential to
cause adverse effects on non-target organisms.  Table 4 of this document
summarizes the LOCs used in this risk assessment. 

1.	Non-target Aquatic Animals  TC \l3 "1.	Non-target Aquatic Animals 

	Freshwater Fish  TC \l4 "a.	Freshwater Fish 

An analysis of the results indicate that aquatic acute restricted use
and endangered species levels of concern are exceeded for freshwater
fish for the cotton (2 applications), soybean and pecan uses, while
endangered species levels of concern are exceeded for the citrus use
patterns. Aquatic acute risk, acute restricted use and endangered
species levels of concern are exceeded for freshwater fish for the
cotton (1 application). Freshwater fish risk quotients are listed in
Table 21.

Table 21.  Acute and chronic risk quotients for freshwater fish  TC
"Table 21.  Acute and chronic risk quotients for freshwater fish" \f E
\l "1"   

Site/

Rate in lbs ai/A/year (No. of apps.)	

LC50

(ppb)	Estimated

ENEC 

( ACR calculation)

(ppb)	EEC

Initial/Peak

(ppb)	EEC

60-Day Avg.

(ppb)	Acute RQ 

(EEC/LC50)	Estimated

Chronic RQ

(EEC/ENEC) 

cotton

4.05 ( 1 app)	52	0.46	28.04	24.55	0.54***	53.36****

cotton

4.95 total (2 apps)  	52	0.46	18.40	15.90	0.35**	34.57****

potato

3.00 (1 app) 	52	0.46	1.43	1.35	0.03	2.93****

citrus

4.95 (1 app) 	52	0.46	2.96	2.50	0.06*	5.43****

soybeans

3.00 (1 app)	52	0.46	7.12	6.05	0.14**	13.15****

pecans

10.05 (1 app)

	52	0.46	12.04	10.19	0.23**	22.15****

Risk quotients for freshwater fish based on a (bluegill sunfish MRID
No.: 40098001) LC50 of  52 ppb. Fathead minnow NOAEC of 78 ppb (MRID
4459860) for technical grade Aldicarb could not be used to calculate an
RQ because it was higher than the LC50 for bluegill sunfish. Therefore,
chronic RQs could only be estimated using the ACR method. A bluegill
sunfish ENEC of 0.46 ppb (calculated in Acute to Chronic ratio as
described in text) was estimated for this purpose.

*exceeds endangered species LOC (LOC = 0.05)

**exceeds endangered species and acute restricted use LOC (LOC = 0.1)

***exceeds endangered species, restricted use and acute risk LOC  (LOC =
0.5)

****exceeds chronic LOC (LOC = 1)

Chronic freshwater fish LOCs are not exceeded if the fathead minnow
NOAEC of 78 ppb is used in the calculations. However, according to the
acute freshwater fish data, the bluegill sunfish is the most sensitive
freshwater fish tested with an LC50 of 52 ppb.  Therefore, chronic risk
to fish was also assessed using a predicted chronic ENEC for the
bluegill sunfish estimated using the acute-to-chronic ratio for the
fathead minnow.  Using a predicted ENEC for the bluegill sunfish in the
RQ calculations produces freshwater fish chronic RQs that exceed the
chronic LOCs for all crop scenarios.

	Freshwater Invertebrates  TC \l4 "b.	Freshwater Invertebrates 

An analysis of the results indicate that aquatic acute restricted use,
and endangered species levels of concern are exceeded for freshwater
invertebrates for citrus and soybeans. The endangered species LOC is
exceeded for the potato use pattern.  Aquatic acute risk, restricted
use, and endangered species levels of concern are exceeded for
freshwater invertebrates for cotton (1 and 2 applications) and pecans.
However, the chronic level of concern is exceeded for all of the
registered aldicarb uses (Tables 22 and 23).

Table 22.  Acute Risk Quotients for Freshwater Invertebrates  TC "Table
22.  Acute Risk Quotients for Freshwater Invertebrates" \f E \l "1"  

Site/

Rate in lbs ai/A/year 

(No. of Apps.)	EC50

(ppb)	EEC

Initial/Peak

(ppb)	Acute RQ

(EEC/EC50)

cotton

4.05 (1 app)	20	28.04	1.40***

cotton

4.95 total (2 apps)  	20	18.40	0.92***

potato

3.00 (1 app) 	20	1.43	0.07*

citrus

4.95 (1 app) 	20	2.96	0.15**

soybeans

3.00 (1 app)	20	7.12	0.36**

pecans

10.05 (1 app)

	20	12.04	0.60***

Risk quotients for freshwater invertebrates based on an adult Chironomus
tetansEC50 of 20 ppb using technical grade Aldicarb (Moore et al. 1998) 

*exceeds endangered species LOC (LOC = 0.05)

**exceeds endangered species and restricted use LOC (LOC = 0.1)

***exceeds endangered species, restricted use and acute risk LOC  (LOC =
0.5)

Table 23.  Chronic risk quotients for freshwater invertebrates.  TC
"Table 23.  Chronic risk quotients for freshwater invertebrates." \f E
\l "1"  

Site/

Rate in lbs ai/A/year 

(No. of Apps.)	NOAEC

(ppb)	EEC

21-Day Avg.

(ppb)	Chronic RQ

(EEC/NOAEC)

cotton

4.05 ( 1 app)	1	26.56	26.56*

cotton

4.95 total (2 apps)  	1	17.53	17.53*

potato

3.00 (1 app) 	1	1.40	1.40*

citrus

4.95 (1 app) 	1	2.80	2.80*

soybeans

3.00 (1 app)	1	6.76	6.76*

pecans

10.05 (1 app)

	1	11.40	11.40*

Chronic RQ calculated using NOAEC for mysid shrimp (Americamysis bahia)
(1.0 ppb).

*exceeds chronic LOC

	Estuarine/Marine Fish  TC \l4 "c.	Estuarine/Marine Fish 

An analysis of the estuarine/marine fish species results indicate that
aquatic acute endangered species LOC are exceeded for citrus, while the
cotton (2 applications), soybean, and pecan uses exceed the acute
restricted use LOC.  The cotton (1 application) scenario exceeds the
acute, restricted, and endangered species LOC.  Chronic levels of
concern could not be reliably determined with the available data. 
Estuarine/marine risk quotients are listed in Table 24.

Table 24.   Acute and chronic risk quotients for estuarine/ marine fish
 TC "Table 24.   Acute and chronic risk quotients for estuarine/ marine
fish" \f E \l "1"  

Site/

Rate in lbs ai/A/year 

(No. of Apps.)	

LC50

(ppb)	

NOAEC

(ppb)	EEC

Initial/Peak

(ppb)	EEC

60-Day Ave.

(ppb)	Acute RQ

(EEC/LC50)	Chronic RQ

(EEC/ENEC)

cotton

4.05 ( 1 app)	41	0.36	28.04	24.55	0.68****	68.19

cotton

4.95 total (2 apps)  	41	0.36	18.40	15.90	0.45***	44.17

potato

3.00 (1 app) 	41	0.36	1.43	1.35	0.03	3.75

citrus

4.95 (1 app) 	41	0.36	2.96	2.50	0.07**	6.94

soybeans

3.00 (1 app)	41	0.36	7.12	6.05	0.17***	16.81

pecans

10.05 (1 app)

	41	0.36	12.04	10.19	0.29***	28.30

Risk quotients for estuarine/marine fish based on a sheepshead minnow
(MRID No.: 40228401) LC50 of 41 ppb and a sheepshead minnow ENEC of 0.36
ppb using technical grade aldicarb

**exceeds listed species LOC (LOC = 0.05)

***exceeds listed species LOC and acute restricted use LOC (LOC = 0.1)

****exceeds listed species, restricted use, and acute risk LOC  (LOC =
0.5)

bold type indicates chronic LOC exceedances

	Estuarine/Marine Invertebrates  TC \l4 "d.	Estuarine/Marine
Invertebrates 

An analysis of the results indicate that aquatic acute risk, restricted
use, and endangered species LOCs are exceeded for the cotton, soybean,
and pecan uses, while the acute restricted and endangered species LOCs
are exceeded for the potato and citrus uses.  Chronic levels of concern
are exceeded for marine/estuarine invertebrates for all registered uses
and rates.

Table 25.   Acute and chronic risk quotients for estuarine/ marine
invertebrates  TC "Table 25.   Acute and chronic risk quotients for
estuarine/ marine invertebrates" \f E \l "1"  .

Site/

Application

Method/ Rate in lbs ai/A/year

(No. of Apps.)	LC50

(ppb)	NOAEC

(ppb)	EEC

Initial/Peak

(ppb)	EEC

21-Day Avg.

(ppb)	Acute RQ

(EEC/LC50)	Chronic RQ

(EEC/NOAEC)

cotton

4.05 ( 1 app)	12	1	28.04	26.56	2.34***	26.56

cotton

4.95 total (2 apps)  	12	1	18.40	17.53	1.53***	17.53

potato

3.00 (1 app) 	12	1	1.43	1.40	0.12**	1.40

citrus

4.95 (1 app) 	12	1	2.96	2.80	0.25**	2.80

soybeans

3.00 (1 app)	12	1	7.12	6.76	0.59***	6.76

pecans

10.05 (1 app)

	12	1	12.04	11.40	1***	11.40

Risk quotients for estuarine/marine invertebrates based on a Pink Shrimp
(Penaeus duorarum MRID No.: 40228401) LC50 of 12 ppb and a Mysid Shrimp
(Americamysis bahia MRID No.: 00066341) NOAEC of 1 ppb using technical
grade aldicarb.

*exceeds endangered species LOC (LOC = 0.05)

**exceeds endangered species and restricted use LOC (LOC = 0.1)

***exceeds endangered species, restricted use and acute risk LOC  (LOC =
0.5)

bold type indicates chronic LOC exceedances

	Risk Quotients Based on Surface Water Monitoring Data  TC \l4 "e.	Risk
Quotients Based on Surface Water Monitoring Data 

In addition to the surface water EECs based on modeling, it is possible
to assess exposure to aquatic organisms using published data on pulse
concentrations of aldicarb following rainfall runoff events.  The Beaver
Creek study took place in western Tennessee in low order streams
draining watersheds ranging from 28 to 422 acres.  The streams were
monitored at five minute intervals for approximately 12 hours after the
start of each storm.  As previously described, high concentrations of
aldicarb (up to 430 ppb parent, and 454 ppb total toxic residues) were
detected following storm events.  Short term exposures to such
concentrations might pose an acute hazard to fish and other organisms in
these systems.  Therefore, risk quotients were calculated for aquatic
animals using the acute endpoint and measured concentrations based on a
12 hour average (0.105 ppm) and the peak concentration of total
aldicarb.  These risk quotients are given in Table 26 below.

Table 26.  Acute risk quotients for aquatic organisms based on actual
field data.  TC "Table 26.  Acute risk quotients for aquatic organisms
based on actual field data." \f E \l "1"  

Test Species	LC50

(ppb)	12 Hour Average EEC

(ppb)	Peak EEC

(ppb)	12 Hour Avg. Risk Quotient

(EEC/LC50)	Peak Risk Quotient

(EEC/LC50)

Bluegill Sunfish

(Freshwater Fish)	52	105	454	2.0*	8.7*

Daphnia magna

(Freshwater Invertebrate)	51	105	454	2.1*	8.9*

Sheepshead Minnow

(Estuarine/Marine Fish)	41	105	454	2.6*	11.1*

Pink Shrimp

(Estuarine/Marine Invertebrate)	12	105	454	8.8*	37.8*

* exceeds acute risk,  restricted use, and endangered species LOC 

**exceeds restricted use and endangered species LOC

Based on both the 12 hour and peak EECs the acute risk, restricted use,
and endangered species levels of concern are exceeded for freshwater
fish, freshwater invertebrates, estuarine/marine invertebrates, and
estuarine/marine fish. 

	Non-target Terrestrial Animals  TC \l3 "	2.	Non-target Terrestrial
Animals 

In the case of aldicarb, which is applied only in a granular form, the
method used in calculating terrestrial EECs took into account this
granular formulation and its soil incorporation.  The model assumes that
only 1% (in-furrow application) or 15% (banded application) of the
applied granules remain on the surface and have the potential for
terrestrial animal exposure.  EECs were calculated based on application
method, application rate, band width (where appropriate), and percent
incorporation of the granules into the soil. 

The LD50 values entered into T-REX are adjusted for animal class (20,
100, and 1000g birds and 15, 35, and 1000g mammals) using the following
equations:

Avian LD50:	Adjusted LD50 = LD50 x (AW/TW) (1.15-1)

  ADVANCE \u 13 

Mammal LD50:  Adjusted LD50 = LD50 x (TW/AW) (0.25)

  ADVANCE \u 13 

Where TW = test weight (specific to animal size) and AW = adjusted
weight (adjusted for animal class).  

The risk assessment indicates that aldicarb poses acute risk to birds
and mammals.  As previously stated, the method used in calculating
terrestrial EECs took into account the granular formulation of the
product and its soil incorporation.  The model assumes that only 1%
(in-furrow application) or 15% (banded application) of the applied
granules remain on the surface and have the potential for terrestrial
animal exposure.  Quantitative chronic risk assessments are not
currently performed for granular pesticides on terrestrial organisms.

The following tables (27 & 28) provide risk quotients that were
calculated based on maximum labeled application rates and the average
application rates taken from the Biological and Economic Analysis
Division’s Quantitative Usage Analysis dated August 9, 2004, as well
as label-indicated band widths and row spacing.  These rates could be
considered more typical of the application rates applied under some use
conditions.  Based on this information, it is evident that risk levels
of concern are exceeded even at rates that are less than the application
rates allowed by the product labels.  

Table 27.  Avian Acute Risk Quotients for Aldicarb (maximum and average
use rates).  TC "Table 27.  Avian Acute Risk Quotients for Aldicarb
(maximum and average use rates)." \f E \l "1"    

Crop Scenario	Bird Type	Maximum Application	Average Application

Rate

 (lbs ai/A)	EEC 

(mg ai/ft2)	RQ	Rate

 (lbs ai/A)	EEC 

(mg ai/ft2)	RQ

Cotton

Banded/Sidedress

4" band width

40" row spacing

15% unincorporated	Small Bird (20g)	4.05	64.1	6395.9	0.6	9.5	947.5

	Medium Bird (80g)	4.05	64.1	1004.8	0.6	9.5	148.9

	Large Bird (1000g)	4.05	64.1	71.1	0.6	9.5	10.5

Dry Beans

Banded

6" band width

48" row spacing

15% unincorporated	Small Bird (20g)	2.1	26.3	2619.9	1.0	12.5	1247.6

	Medium Bird (80g)	2.1	26.3	411.6	1.0	12.5	196.0

	Large Bird (1000g)	2.1	26.3	29.1	1.0	12.5	13.4

Sorghum

Banded

2" band width

36" row spacing

1% unincorporated	Small Bird (20g)	1.05	1.9	192.6	0.4	0.7	73.4

	Medium Bird (80g)	1.05	1.9	30.3	0.4	0.7	11.5

	Large Bird (1000g)	1.05	1.9	2.1	0.4	0.7	0.8

Peanuts

Banded

6" band width

36" row spacing

15% unincorporated	Small Bird (20g)	3.0	28.1	2807.1	0.9	8.4	842.1

	Medium Bird (80g)	3.0	28.1	441.0	0.9	8.4	132.3

	Large Bird (1000g)	3.0	28.1	31.2	0.9	8.4	9.4

Potatoes

Banded

6" band width

38" row spacing

15% unincorporated	Small Bird (20g)	3.0	29.7	2963.0	2.7	26.7	2666.7

	Medium Bird (80g)	3.0	29.7	465.5	2.7	26.7	419.0

	Large Bird (1000g)	3.0	29.7	33.0	2.7	26.7	29.7

Soybeans

Banded

6" band width

30" row spacing

15% unincorporated	Small Bird (20g)	3.0	23.5	2339.2	0.7	5.5	545.8

	Medium Bird (80g)	3.0	23.5	365.5	0.7	5.5	85.8

	Large Bird (1000g)	3.0	23.5	26.0	0.7	5.5	6.1

Sugar Beets

Banded

6" band width

22" row spacing

15% unincorporated	Small Bird (20g)	4.95	28.4	2830.5	1.8	9.7	972.1

	Medium Bird (80g)	4.95	28.4	444.7	1.8	9.7	152.7

	Large Bird (1000g)	4.95	28.4	31.5	1.8	9.7	10.8

Sweet Potatoes

Banded

12" band width

48" row spacing

1% unincorporated	Small Bird (20g)	3.0	1.3	124.8	1.4	0.6	58.2

	Medium Bird (80g)	3.0	1.3	19.6	1.4	0.6	9.2

	Large Bird (1000g)	3.0	1.3	1.4	1.4	0.6	0.7

Citrus

Broadcast

15% unincorporated	Small Bird (20g)	4.95	7.7	771.3	3.7	5.8	576.6

	Medium Bird (80g)	4.95	7.7	121.2	3.7	5.8	90.6

	Large Bird (1000g)	4.95	7.7	8.6	3.7	5.8	6.4

Pecans

Broadcast

15% unincorporated	Small Bird (20g)	10.05	15.7	1566.0	3.1	4.8	483.1

	Medium Bird (80g)	10.05	15.7	246.0	3.1	4.8	75.9

	Large Bird (1000g)	10.05	15.7	17.4	3.1	4.8	5.4

Ornamentals

Broadcast

15% unincorporated	Small Bird (20g)	5.0	7.8	779.1	NA*	NA	NA

	Medium Bird (80g)	5.0	7.8	122.4	NA	NA	NA

	Large Bird (1000g)	5.0	7.8	8.7	NA	NA	NA

Based on Mallard Duck LD50 of 1.0 mg/kg1

bold type indicates LOC exceedances

*Average use rates not available for ornamental applications

1Based on scaling factor of 1.15 (default) in T-REX

The avian T-REX default scaling factor (based on the slope of the
regression of Log (LD50) against Log (weight)) of 1.15 was used in the
RQ calculations (see above equation) to adjust for size-influenced
sensitivity (e.g., smaller birds are more sensitive to aldicarb toxicity
than larger birds).  However, research by Mineau et al. (1996) suggests
that the scaling factor for aldicarb should be 1.4, rather than 1.15. 
Substituting the aldicarb-specific scaling factor of 1.4 into the above
avian equation results in RQ values as high as 22,000 (20g bird, maximum
cotton application rate).  It is therefore possible that the RQ
calculations presented in this risk assessment are underestimated.  

Table 28.  Mammalian Acute Risk Quotients for Aldicarb (maximum and
average use rates  TC "Table 28.  Mammalian Acute Risk Quotients for
Aldicarb (maximum and average use rates" \f E \l "1"  ).  

Crop Scenario	Mammal Size	Maximum Application	Average Application

Rate

 (lbs ai/A)	EEC 

(mg ai/ft2)	RQ	Rate

 (lbs ai/A)	EEC 

(mg ai/ft2)	RQ

Cotton

Banded/Sidedress

4" band width

40" row spacing

15% unincorporated	15g	4.05	64.1	2160.7	0.6	9.5	320.1

	35g	4.05	64.1	1144.5	0.6	9.5	169.6

	1000g	4.05	64.1	92.6	0.6	9.5	13.7

Dry Beans

Banded

6" band width

48" row spacing

15% unincorporated	15g	2.1	26.3	885.1	1.0	12.5	421.5

	35g	2.1	26.3	468.8	1.0	12.5	223.3

	1000g	2.1	26.3	37.9	1.0	12.5	18.1

Sorghum

Banded

2" band width

36" row spacing

1% unincorporated	15g	1.05	1.9	65.1	0.4	0.7	24.8

	35g	1.05	1.9	34.5	0.4	0.7	13.1

	1000g	1.05	1.9	2.8	0.4	0.7	1.1

Peanuts

Banded

6" band width

36" row spacing

15% unincorporated	15g	3.0	28.1	948.3	0.9	8.4	284.5

	35g	3.0	28.1	502.3	0.9	8.4	150.7

	1000g	3.0	28.1	40.6	0.9	8.4	12.2

Potatoes

Banded

6" band width

38" row spacing

15% unincorporated	15g	3.0	29.7	1001.0	2.7	26.7	900.9

	35g	3.0	29.7	530.2	2.7	26.7	477.2

	1000g	3.0	29.7	42.9	2.7	26.7	38.6

Soybeans

Banded

6" band width

30" row spacing

15% unincorporated	15g	3.0	23.5	790.3	0.7	5.5	184.4

	35g	3.0	23.5	418.6	0.7	5.5	97.7

	1000g	3.0	23.5	33.9	0.7	5.5	7.9

Sugar Beets

Banded

6" band width

22" row spacing

15% unincorporated	15g	4.95	28.4	956.2	1.8	9.7	328.4

	35g	4.95	28.4	506.5	1.8	9.7	174.0

	1000g	4.95	28.4	41.0	1.8	9.7	14.1

Sweet Potatoes

Banded

12" band width

48" row spacing

1% unincorporated	15g	3.0	1.25	42.1	1.4	0.6	19.7

35g	35g	3.0	1.25	22.3	1.4	0.6	10.4

1000g	1000g	3.0	1.25	1.8	1.4	0.6	0.8

Citrus

Broadcast

15% unincorporated	15g	4.95	7.7	260.6	3.7	5.8	194.8

	35g	4.95	7.7	138.0	3.7	5.8	103.2

	1000g	4.95	7.7	11.2	3.7	5.8	8.3

Pecans

Broadcast

15% unincorporated	15g	10.05	15.7	529.1	3.1	4.8	163.2

	35g	10.05	15.7	280.2	3.1	4.8	86.4

	1000g	10.05	15.7	22.7	3.1	4.8	7.0

Ornamentals

Broadcast

15% unincorporated	15g	5.0	7.8	263.2	NA*	NA	NA

	35g	5.0	7.8	139.4	NA	NA	NA

	1000g	5.0	7.8	11.3	NA	NA	NA

Based on Rat LD50 of 0.9 mg/kg.

bold type indicates LOC exceedances

*Average use rates not available for ornamental applications

Risk quotients for birds and mammals all exceed the acute risk,
restricted use, and endangered species levels of concern.  Acute avian
and mammalian risk quotients exceed the acute risk level of concern of
0.5 by from 1 to 12,000 fold and 1 to 4,300 fold, respectively.  Listed
below (Table 29) are the ranges of acute avian and mammalian risk
quotients from both average and maximum labeled use rates.

Table 29.  Ranges of Acute Avian and Mammalian Risk Quotients  TC "Table
29.  Ranges of Acute Avian and Mammalian Risk Quotients" \f E \l "1"  

Crop	Avian	Mammalian

Citrus	6.4 - 771.3	8.3 - 260.6

Cotton	10.5 - 6395.9	13.7 - 2160.7

Dry Beans	13.9 - 2619.9	18.1 - 885.1

Sorghum	0.8 - 192.6	1.1 - 65.1

Peanuts	9.4 - 2807.1	12.2 - 948.3

Pecans	5.4 - 1566.0	7.0 - 529.1

Potatoes	29.7 - 2963.0	38.6 - 1001.0

Soybeans	6.1 - 2339.2	7.9 - 790.3

Sugar beets	10.8 - 2830.5	14.1 - 956.2

Sweet potatoes	0.7 - 124.8	0.8 - 42.4

Ornamental	8.7 - 779	11 - 263

Risk quotients (RQs) for aldicarb range from 0.7 (sweet potatoes) to
6395.9 (cotton) for birds and mammals.  All of these RQs exceed the
acute risk LOC of 0.5.  The methodology that is used to calculate the
risk index takes into account application methods and aldicarb’s
formulation.  In the case of aldicarb, this chemical is applied as a
granule and then is incorporated into the soil.  Even under these
conditions aldicarb exceeds the acute risk, restricted use, and
endangered species levels of concern.  However, label language requiring
soil incorporation and the use of only granular formulations aids in
reducing exposure to terrestrial organisms.

Field Studies

Several field studies have been conducted that assess the impact of
aldicarb to terrestrial organisms.  In general, these studies support
the Agency conclusion of acute risk to birds and mammals.

a) Clarkson et al. (1969): Determined the mortality of bobwhite quail
housed for seven days on hard soil that had been treated with 10%
aldicarb granules using different application methods. When plots were
not irrigated, the mortality of quail was very high (6 out of 6 in a
plot with in-furrow application, and 5 out of 6 in a plot with
broadcast/incorporated application).  Mortality was lower when the
application was followed by irrigation (0 out of 6 in a plot with
in-furrow application and 3 out of 6 in a plot with
broadcast/incorporated application).  These findings suggest that the
risk of aldicarb to terrestrial wildlife may be reduced by application
irrigation immediately following application. 	

b) Bunyan et al (1981): Aldicarb was applied to sugar beets during a
field test (1 lb/A), and chemical analysis indicated that both birds and
mammals were exposed to the chemical.  Additionally, one bird
(red-legged partridge) died from granule ingestion.  Results also
indicated that although aldicarb is not particularly persistent that it
is very mobile in wet soil, systemic in plants, and can be found in
local vertebrate fauna for up to 90 days post-application. 
Additionally, ingestion of earthworms that come to the soil surface
following aldicarb application poses an additional dietary hazard to
birds

c) Report #222473 (1987): At the Agency’s request, a field study was
conducted to determine the acute risk of aldicarb to birds and mammals. 
This study assessed the hazard posed by the use of TEMIK® 15G on
citrus, cotton, and potatoes in five states.  The studies suffered from
many deficiencies, including the use of treatments that did not
represent upper end exposure conditions, and the use of inadequate
carcass searching methods.  For these reasons, the finding were
considered inadequate for drawing conclusions on the high end impact of
aldicarb use on populations of terrestrial wildlife.  Rather, the
results provide an indication of what the minimum impacts to birds and
mammals might be under typical use conditions.  In every state and every
crop studied, considerable numbers of dead birds, mammals, and
amphibians were found in and around fields after treatment with aldicarb
(Table 30).  Significantly, residue analysis confirmed aldicarb to be
the cause of death for several of the mortalities in each plot.  Thus,
despite the deficiencies, the Agency review of the study concluded that
“aldicarb use in the listed crops poses a hazard (both lethal and
sublethal) of unknown significance to a variety of non-target wildlife
species.

Table 30.  Number of wildlife carcasses found in a 1987 field study on
the hazard of aldicarb to terrestrial wildlife  TC "Table 30.  Number of
wildlife carcasses found in a 1987 field study on the hazard of aldicarb
to terrestrial wildlife" \f E \l "1"   (Report #222473)

CROP	STATE	RESULTS FROM 1987 FIELD STUDY

Total reported # of wildlife carcasses found	# of carcasses which the
Agency concluded could be attributed to aldicarb	# of carcasses linked
to aldicarb poisoning by residue analysis

Citrus	FL	17	16	9

Citrus	TX	16	16	2

Cotton	TX	16	15	2

Cotton	AZ	5	5	1

Potatoes	DE	5	5	3

Potatoes	ID	11	9	1

Potatoes	MI	6	6	4

d) Pest Infestation Control Laboratory.  1978: Seven bird die-off
incidences were reported in Great Britian from 1975 to 1976 involving
from 3 to 100 birds each.  The die-offs involved several species and
were largely attributed to the ingestion of granules from the soil
surface.

e) RPAC. 1988.(MRID No. 406075-03):  This study confirms that non-target
organism exposure to aldicarb granules on soil surface is reduced by
incorporation, disengaging the applicator before row end, and disking
spilled granules.  As a qualitative assessment study, the degree that
exposure is reduced can not be defined.

f)  Kendall, R.J. 1990. (MRID No.417086-04):  This study is
scientifically sound.  A pen study produced an LD50 of 0.804 while a
dose-release study produced an LD50 of approximately of 1 mg/kg,
classifying aldicarb as very highly toxic to mourning doves.  This
magnitude of toxicity, combined with the steep slope of the dose
response curve (6.2), indicates a high risk of toxicity even at
extremely low concentrations in the environment.  With a very small
sample size in the dose-release study where 5 doves died, apparently
from acute toxicity, and 3 doves died from predators (including a car),
it is difficult to draw any conclusions as to carcass search efficacy.

g) Kendall 1992. (MRID No. 42446501):  The dose-release studies indicate
that a single oral dose of aldicarb, at less than one half the published
LD50 (2 mg/kg), significantly reduces the survival of quail after
release under field conditions.  It appears that most receiving lethal
doses would not be able to obtain cover before death, making the
recovery more likely using standard carcass searches.  However, quail
receiving sublethal doses may experience high mortality that would not
be evident by using standard carcass searches.

	Non-target Terrestrial Invertebrates  TC \l3 "3.	Non-target Terrestrial
Invertebrates 

	Honeybee  TC \l4 "a.	Honeybee 

Honeybee toxicity values indicate that aldicarb is highly toxic to this
insect species.  This indicates that there is potential risk to
honeybees as well as other beneficial insects.

	Earthworm  TC \l4 "b.	Earthworm 

This estimation of earthworm concentration was calculated using a
fugacity-based (equilibrium partitioning) approach based on the work of
Trapp and McFarlane (1995) and Mackay and Paterson (1981).  Earthworms
dwelling within the soil are exposed to contaminants in both soil pore
water and via the ingestion of soil (Belfroid et al. 1994).  The
concentrations of aldicarb and its degradates in earthworms were
calculated as a combination of uptake from soil pore water and
gastrointestinal absorption from ingested soil:

		C earthworm = [(Csoil)(Zearthworm/Zsoil)]+[(Csoil
water)(Zearthworm/Zwater)]

earthworm)/H

		Zsoil is the fugacity capacity of chemical in soil = (Kd)(soil)/H

		Zwater is the fugacity capacity of chemical in water = 1/H

		Csoil water is the concentration of chemical in soil water = Csoil/Kbw

		Kbw  is the bulk soil-to-water partitioning coefficient =
(soil)(Kd)+ +(-)(Kaw)

		Kaw is the air-to-water partitioning coefficient = H/RT

		H = Henry’s Constant specific to aldicarb

		R = universal gas constant, 8.31 Joules-m3/mol-oK

		T = temperature oK, assumed to be 298 oK

		Kd = soil partitioning coefficient = (chemical Koc)(0.02 assumed
fraction of soil organic carbon)

		soil = bulk density of soil, assumed to be 1.3 g/cm3

		 = volumetric fraction of the soil, assumed to be 0.30

		 = volumetric total porosity of the soil, assumed to be 0.50

		lipid = fraction of lipid in organism 0.01 (Cobb et al. 1995)

		Kow = aldicarb or degradate octanol to water partitioning coefficient

		earthworm = the density of the organism g/cm3, assumed to be 1
g/cm3

Assuming the maximum application rate of aldicarb of 10.0 lb/acre (11.2
kg/ha) to a bare, very low density soil (1.3 g/cm3) incorporated to
15-cm depth (actual incorporation depths may range from 5 to 20 cm), the
following soil concentrations can be calculated for a depth of 15 cm:

 

Based on this soil concentration calculation of 9.7 mg/kg, the
concentration of aldicarb in an earthworm based on the above earthworm
fugacity model equation (using the maximum application rate) would be
11.7 mg/kg (for detailed calculations, see Appendix G).  

Assuming the lowest average aldicarb application rate (cotton) of 0.6
lbs ai/A (0.675 kg./ha) to the same soil, the soil concentration at a
depth of 15 cm would be 0.6 mg/kg.  Based on this concentration, the
concentration of aldicarb in an earthworm following application to
cotton at the lowest average rate would be 0.7 mg/kg.  According to the
study by Mosleh et al. (2003), the earthworm LC50 is 0.68 mg/kg,
indicating that following maximum aldicarb application rate (pecans) as
well as the lowest average application rate (cotton), there is
substantial risk to earthworm species based on this toxicity endpoint.

The calculated earthworm tissue concentrations of aldicarb suggest that
ingestion of earthworms by birds and mammals (aldicarb LD50 = 1.0 mg/kg
and 0.9 mg/kg, respectively) could be a significant exposure pathway
resulting in high acute risk.  The European Union has placed a ban on
aldicarb.  One of the primary reasons for this legal action is the high
acute toxicity of aldicarb to earthworms.  

	Non-target Terrestrial and Aquatic Plants  TC \l3 "4.	Non-target
Terrestrial and Aquatic Plants 

As described in the analysis section, there were no registrant-submitted
terrestrial plant studies, and those studies found in the open
literature (ECOTOX) did not provide the necessary endpoints to
quantitatively calculate risk. However, results of the open literature
studies indicated low toxicity of aldicarb to terrestrial plants due to
the lack of effects (seedling emergence) in the studies.  

There is one aquatic plant study (diatom) that was used descriptively to
discuss potential risk to aquatic plants. Comparisons of the diatom
toxicity study and the aquatic EEC values indicated minimal aquatic
plant risk.

B.	Risk Description - Interpretation of Direct Effects  TC \l2 "B.	Risk
Description - Interpretation of Direct Effects  

1.	Risks to Aquatic Animals   TC \l3 "1.	Risks to Aquatic Animals  

Summary of Major Conclusions

Acute Risk

There is acute risk for freshwater fish with RQs ranging from 0.06 to
0.54.  The bluegill fish LC50 value of 52 ppb was used in the
calculations.  Based on comparison of various fish toxicities of
bluegill, rainbow trout and fathead minnow, it appears the bluegill is
the most sensitive species. There is also acute risk to freshwater
invertebrates (RQ range of 0.07 to 1.40) using the most sensitive
endpoint of EC50 of 20 ppb for Chronomus tetans.  A comparison of
freshwater invertebrate toxicities indicates Chronomus tetans is more
sensitive than other invertebrate species including Daphnia magna, Aedes
aegypti, Atermia sp., Aedes taeniorhynchus, and Hyalella azteca.  

There is acute risk to estuarine/marine fish with RQs ranging from 0.07
to 0.68.  The LC50 value of 41 ppb for the sheepshead minnow were used
in calculations and appears representative of  estuarine/marine fish (an
additional study for the snook reported LC50 value of 40 ppb). Acute
risk to estuarine/marine invertebrates was observed (RQ range of 0.12 to
2.34).  The pink shrimp was the most sensitive estuarine/marine
invertebrate tested.

Chronic Risk

The chronic level of concern is not exceeded for freshwater fish when
the fathead minnow NOAEC value of 78 ppb is used in calculations. 
However, the fathead minnow was not the most sensitive species in the
acute toxicity testing.  The bluegill was identified as the most
sensitive freshwater fish species.  Therefore, when an acute to chronic
ratio is calculated and an estimated ENEC of 0.46 ppb for the bluegill
is used for RQ calculations, the chronic level of concern is exceeded
for all crop scenarios. The endpoint identified was larval and juvenile
survival after 30 days. There is some uncertainty involved in using
acute to chronic ratios for toxicity endpoints determination.  However,
the use of the less sensitive fathead minnow NOAEC does not address
potential chronic risk to more sensitive freshwater fish species.

The chronic level of concern is exceeded for freshwater invertebrates
(reproductive effects endpoint) for all crop scenarios (RQ range of 1.40
to 26.56).  The RQ calculation used a mysid shrimp NOAEC of 1 ppb. 
There is some uncertainty with the use of an estuarine/marine
invertebrate NOAEC, however, this was agreed to by the Agency and
registrant to waive a study requirement 

Chronic risk to estuarine/marine fish could not be determined using the
sheepshead NOAEC because the available data indicates the NOAEC is
greater than the acute LC50.  Therefore, an ENEC was derived for the
sheepshead minnow using the fathead minnow ACR. The chronic level of
concern is exceeded for estuarine/marine fish for all crop scenarios
based on the ENEC of 0.36. There is some uncertainty involved in using
acute to chronic ratios for toxicity endpoints determination.  

The chronic level of concern is exceeded for estuarine/marine
invertebrates (average number of offspring endpoint) for all of the
registered uses.  The RQ calculation used a mysid shrimp NOAEC of 1 ppb

Risk using Monitoring Data

Monitoring data indicate that aldicarb residues (including the sulfone
and sulfoxide products) are likely to exceed levels of concern for fish
and aquatic invertebrates only in smaller (lower-order) streams in high
use areas.  Risk quotient exceedances of aquatic levels of concern are
based on monitoring data and not on modeling.

2.  	Risks to Terrestrial Animals   TC \l3 "	2.  	Risks to Terrestrial
Animals  

Summary of Major Conclusions

Comparison of the acute oral LD50s for rats indicates that aldicarb is
the most toxic of the carbamate and organophosphate pesticides to
mammalian species (Smith, 1987).  The conclusions of this
screening-level risk assessment indicate that aldicarb use, at both
maximum and average rates on all crops, may pose significant risk to
mammals and birds.  The acute risk, acute restricted use, and acute
endangered species LOCs for mammals and birds are exceeded for all
target crops at all modeled application rates.  These acute LOCs are
consistently exceeded by a factor of greater than 100x and are
frequently exceeded by more than 1000x.  

The most sensitive bird species tested on an acute basis is the mallard
duck with an LD50 of 1.0 ppm.  On a subacute basis, it appears the
bobwhite quail is the most sensitive species (LC50 = 71 ppm). Based on
the acute and subacute toxicity studies for birds, the relative toxicity
relationship is: aldicarb>aldicarb sulfoxide> aldicarb sulfone.

Aldicarb field data studies support the conclusions of the risk
assessment.  Seven field studies (see pages 50 - 51) showed bird,
mammal, amphibian, and earthworm mortalities following aldicarb
application.  

	Threatened and Endangered Species Concerns

  TC \l2 "C.	Threatened and Endangered Species Concerns 

	Taxonomic Groups Potentially at Risk  TC \l3 "1.	Taxonomic Groups
Potentially at Risk 

The Agency’s levels of concern for endangered and threatened
freshwater fish and invertebrates, estuarine/marine fish and
invertebrates, birds, and mammals for aldicarb use.  Appendix H provides
a list of endangered and threatened species for each crop where aldicarb
is used.  The Agency recognized that there are no Federally listed
estuarine/marine invertebrates or mollusks.  A summary of the endangered
species taxonomic groups potentially at risk from aldicarb use are
listed in Table 31.

The preliminary risk assessment for endangered species indicates that
aldicarb exceeds the endangered species LOCs for the following
combinations of analyzed uses and species:

Freshwater fish (acute): use on cotton, citrus, soybean, and pecan crops
at maximum labeled use rates

Freshwater invertebrates (acute):  use on cotton, citrus, soybean, and
pecan crops at maximum labeled use rates

Estuarine/marine fish (acute): use on cotton, citrus, pecan, and soybean
crops at maximum use rates

Estuarine/marine invertebrates (acute):  use on cotton, potato, citrus,
pecan, and soybean crops at maximum use rates

Birds (acute):  use on dry beans, citrus, cotton, peanuts, pecans,
potatoes, sorghum, soybeans, sugar beets, and sweet potatoes at maximum
and average use rates

Mammals (acute): use on dry beans, citrus, cotton, peanuts, pecans,
potatoes, sorghum, soybeans, sugar beets, and sweet potatoes at maximum
and average use rates

Table 31.  Tabulation by taxonomic group and crop of listed species
that occur in aldicarb use areas  TC "Table 31.  Tabulation by taxonomic
group and crop of listed species that occur in aldicarb use areas" \f E
\l "1"  

Crop	Taxonomic Group

	Birds	Mammals	Reptiles	Amphibians	Fish	Crustaceans	Arachnids	Insects
Snails	Clams	Plants

Dry Beans (edible)	19	27	8	7	29	5	0	13	7	2	118

Citrus, all	45	31	18	7	22	9	1	17	2	0	326

Cotton	25	29	16	13	49	8	4	12	12	44	129

Peanuts	15	10	7	4	12	1	6	6	0	26	28

Pecans	31	35	20	15	65	11	10	18	15	48	179

Potatoes	32	39	19	13	57	11	1	22	12	45	217

Sorghum	22	29	14	11	52	11	10	17	5	55	120

Soybeans	19	17	13	6	40	8	1	8	15	68	93

Sugar Beets	14	15	5	4	20	4	0	9	6	1	63

Sweet Potatoes	28	15	10	4	25	5	1	7	2	38	183

Total Unique Species	56	57	27	18	87	20	12	40	28	70	490

Total States	38	37	17	11	32	11	3	19	13	22	38

	USFWS Biological Opinions  TC \l3 "1.	USFWS Biological Opinions 

In 1982 the U.S. Fish and Wildlife Service (USFWS) issued a case-by-case
biological opinion (USFWS 1982) for aldicarb  in response to the U. S.
Environmental Protection Agency’s request for consultation for use of
TEMIK® in tomatoes, sorghum, grapefruit, lemons and limes.  In issuing
its opinion the USFWS considered the following factors in terms of
potential exposure to endangered species: (1) direct ingestion of
granules (2) indirect exposure through ingestion of invertebrates,
birds, or other small mammals, which have died from exposure to TEMIK®,
(3) ingestion of earthworms that have granules adhering to their mucoid
epidermis, and (4) because of the systemic action of the chemical to
translocate via the root system-ingestion of vegetation.

Based on dietary habits, habitat requirements, crop use patterns and
distributions of the species the USFWS concluded that… “with the
exception of the San Joaquin kit fox (Vulpes macrotis mutica) and the
Attwater’s greater prairie chicken (Tympanuchus cupido attwateri),
listed species would be precluded from adverse exposure”.  They
further concluded that although there was a potential for secondary
poisoning, the impact was... “not likely to jeopardize the continued
existence of the San Joaquin kit fox.” However, because of the
extensive use of sorghum fields by the Attwater’s greater prairie
chicken and because just one granule of either the 10G or 15G
formulation exceeded the LD50 for 2-week old chicks, the opinion
concluded that the use of aldicarb on sorghum was likely to jeopardize
the continued existence of the Attwater’s greater prairie chicken.

In addition to the 1982 case-by-case opinion the USFWS also completed a
“cluster opinion for aldicarb for cotton, soybeans, sorghum, and small
grains (USFWS , 1983). In its’ opinion the service identified two
avian species: the Attwater’s greater prairie chicken, Tympanuchus
cupido attwateri  and the Aleutian Canada goose (Branta canadensis
leucopareia) , two freshwater fish species: the Woundfin, (Plagopterus
argentissimus) and the Slackwater darter, (Etheostoma boschungi) and
twelve freshwater mussels: the Alabama lamp pearly mussel, (Lampsilis
virescent), the  Appalachian monkeyface pearly mussel (Quadrula sparsa),
the Cumberlan monkeyfaced pearly mussel, (Q. intermedia), the dromedary
pearly mussel (Dromus dromas), the birdwing pearly mussel (Conradilla
caelata), the Cumberland bean pearly mussel (Villosa [=Micromya]
trabalis), green-blossom pearly mussel (Epioblasma [=Dysnomia]
torulose/gubernaculum), turgid blossum pearly mussel (E. [Dysnomia]
turgidula), tan riffle shell (E. walkeri), pale lillyput pearly mussel
(Toxolasma [= Carunculina cylindrella), fine-rayed pigtoe (Fusconaia
cuneolus) and shiny pigtoe (F. edgariana) as likely to be in jeopardy
from the use of aldicarb on those crops identified in the cluster
opinion. To preclude jeopardy to these species the opinion, the USFWS
recommended that certain specific reasonable and prudent alternatives to
be implemented as a condition of use.

Since these two biological opinions have been issued, many additional
species, especially aquatic species, have been federally listed as
endangered/threatened.  As such additional consultations with the USFWS
may be required in order to determine jeopardy and/or reasonable and
prudent alternatives. Toward this end, 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 this 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.  A final Endangered
Species Protection Program, which may be altered from the interim
program, was proposed for public comment in the Federal Register
December 2, 2002.

	Probit Slope Analysis  TC \l3 "2.	Probit Slope Analysis 

The probit slope response relationship is evaluated to calculate the
change of an individual event corresponding to the listed species acute
LOCs.  If information is unavailable to estimate a slope for a
particular study, a default slope assumption of 4.5 is used as per
original Agency assumptions of typical slope cited in Urban and Cook
(1986).

Freshwater Fish

Raw data is not provided in the bluegill sunfish acute LC50 study (MRID
400098001) to calculate a slope.  Therefore, the event probability was
calculated for aquatic LOC based on a default slope of 4.5.  RQ
exceedances occur for freshwater fish species at all aldicarb
application scenarios with the exception of the potato.  The individual
mortality associated with the minimum and maximum calculated RQ values
(0.06 and 0.54) result in an estimated chance of individual mortality
ranging from of 1 in 8 (12.5%) to 1 in 5.20E +07, respectively. Based on
an assumption of a probit dose response relationship with a mean
estimated slope of 4.5, the corresponding estimated chance of individual
mortality associated with the listed species LOC of 0.05 is 1 in 4.17E
+08.  

Freshwater Invertebrates

Raw data is not provided in the daphnid acute EC50 study (Foran et al.
1985) to calculate a slope.  RQ exceedances occur for freshwater
invertebrate species at all aldicarb application scenarios with the
exception of the potato.  Based on the default slope assumption of 4.5,
the individual mortality associated with the minimum and maximum
calculated RQ values (0.06 and 0.55) result in an estimated chance of
individual mortality ranging from of 1 in 8 (12.5%) to 1 in 5.20E +07,
respectively. The corresponding estimated chance of individual mortality
associated with the listed species LOC of 0.05 is 1 in 4.17E +08.

Estuarine and Marine Fish

Raw data is not provided in the sheepshead minnow acute LC50 study (MRID
40228401) to calculate a slope.  Therefore, the event probability was
calculated for aquatic LOC based on a default slope of 4.5.  RQ
exceedances occur for estuarine and marine fish species at all aldicarb
application scenarios with the exception of the potato.  The individual
mortality associated with the minimum and maximum calculated RQ values
(0.07 and 0.68) result in an estimated chance of individual mortality
ranging from of 1 in 4 (25 %) to 1 in 9.86E +06, respectively.  The
corresponding estimated chance of individual mortality associated with
the listed species LOC of 0.05 is 1 in 4.17E +08.

Estuarine and Marine Invertebrates

Raw data is not provided in the pink shrimp acute LC50 study (MRID
40228401) to calculate a slope.  The default slope assumption of 4.5 was
used.  RQ exceedances occur for estuarine and marine invertebrate
species at all aldicarb application scenarios.  The individual mortality
associated with the minimum and maximum calculated RQ values (0.12 and
2.34) result in an estimated chance of individual mortality ranging from
of 1 in 1 (100 %) to 1 in 5.85E +04, respectively.  The corresponding
estimated chance of individual mortality associated with the listed
species LOC of 0.05 is 1 in 4.17E +08.

Based on these calculations, any RQ value that is above a value of 1.1
results in an estimated chance of individual mortality of 100%.
Therefore, with the cotton (1 application) and cotton (2 applications)
scenarios with RQs of 2.34 and 1.53, respectively, indicates 100% chance
of individual mortality.

Birds

Analysis of raw data from the Mallard duck acute toxicity study (MRID
107398) estimate a slope of 8.49 (95% C.I. 3.73 - 13.26).  Based on this
slope, and taking into account the RQ exceedances that occur for avian
species at all aldicarb application rates (maximum and average) and with
all application scenarios,  the individual mortality associated with the
maximum and minimum calculated RQ values (0.6 and 6395.9) result in an
estimated chance of individual mortality of 1 in 33.5 (3%) and 1 in 1
(100%), respectively. Based on these calculations, any RQ value that is
above a value of 1.6 results in an estimated chance of individual
mortality of 100%.  Only 4 out of the 63 calculated RQ values for avian
species are below this value, indicating that for both maximum and
average application rates on all modeled crops, nearly all scenarios
estimate individual mortality of endangered avian species exposed to
aldicarb to be 100%.  

Based on this slope and the endangered species avian acute LOC of 0.1,
the corresponding estimate chance of individual mortality of avian
species following aldicarb application is 1 in 10,000,000,000.  To
explore possible bounds to such estimates, the upper and lower values
for the mean slope estimate (3.73 - 13.26) can be used to calculate
upper and lower estimates of the effects probability associated with the
listed species LOC.  These values are 1 in 10,400 and 1 in 1x1016.  

Mammals

Raw data is not provided in the rat acute LD50 study (MRID 00057333) to
calculate a slope.  Therefore, the event probability was calculated for
mammalian LOC based on a default slope of 4.5 (with a range from 2 - 9).
 RQ exceedances occur for mammalian species at all aldicarb application
rates (maximum and average) and with all application scenarios.  The
individual mortality associated with the minimum and maximum calculated
RQ values (0.8 and 2160.7) result in an estimated chance of individual
mortality of 1 in 3 (33%) and 1 in 1 (100%), respectively. Based on
these calculations, any RQ value that is above a value of 2.5 results in
an estimated chance of individual mortality of 100%.  Only 3 out of the
63 calculated RQ values for mammalian species are below this value,
indicating that for both maximum and average application rates on all
modeled crops, nearly all scenarios estimate individual mortality of
endangered mammalian species exposed to aldicarb to be 100%.    

Based on an assumption of a probit dose response relationship with a
mean estimated slope of 4.5, the corresponding estimated chance of
individual mortality associated with the mammalian listed species LOC of
0.1 is 1 in 294,000.  

It is recognized that extrapolation of very low probability events is
associated with considerable uncertainty in the resulting estimates.  To
explore possible bounds to such estimates, the upper and lower values
for the mean slope estimate can be used to calculate upper and lower
estimates of the effects probability associated with the listed species
LOC.  However, since slope is based on a default assumption of 4.5, the
95 percent confidence intervals for the slopes are unavailable.  

	Critical Habitat  TC \l3 "4.	Critical Habitat 

In the evaluation of pesticide effects on designated critical habitat,
consideration is given to the physical and biological features
(constituent elements) of a critical habitat identified by the FWS and
NMFS as essential to the conservation of a listed species and which may
require special management considerations or protection.  The evaluation
of impacts for a screening level pesticide risk assessment focuses on
the biological features that are constituent elements and is
accomplished using the screening level taxonomic analysis (risk
quotients, RQs) and listed species levels of concern (LOCs) that are
used to evaluate direct and indirect effects to listed organisms.

The screening level risk assessment has identified potential concerns
for indirect effects on listed species for those organisms dependent
upon freshwater fish and invertebrates, estuarine/marine fish and
invertebrates, birds, and mammals..  In light of the potential for
indirect effects, the next step for EPA, FWS, and the NMFS is to
identify which listed species and critical habitat are potentially
implicated.

Analytically, the identification of such species and critical habitat
can occur in either of two ways.  First, the agencies could determine
whether the action area overlaps critical habitat or the occupied range
of any listed species.  If so, EPA would examine whether the
pesticide’s potential impacts on non-endangered species would affect
the listed species indirectly or directly affect a constituent element
of the critical habitat.  Alternatively, the agencies could determine
which listed species depend on biological resources, or have constituent
elements that fall into, the taxa that may be directly or indirectly
impacted by the pesticide.  Then EPA would determine whether use of the
pesticide overlaps with the critical habitat or the occupied range of
those listed species.  At present, the information reviewed by EPA does
not permit use of either analytical approach to make a definitive
identification of species that are potentially impacted indirectly or
critical habitats that are potentially impacted directly by the use of
the pesticide.  EPA and the Service(s) are working together to conduct
the necessary analysis.  

This screening level risk assessment for critical habitat provides a
listing of potential biological features that, if the are constituent
elements of one or more critical habitats, would be of potential
concern.  These correspond to the taxa identified above as being of
potential concern for indirect effects and include the following:
freshwater fish and invertebrates, estuarine/marine fish and
invertebrates, birds, and mammals.  This list should serve as an initial
step in problem formulation for further assessment of critical habitat
impacts outlined above, should additional work be necessary.  

	Indirect Effect Analyses  TC \l3 "5.	Indirect Effect Analyses 

The Agency acknowledges that pesticides have the potential to exert
indirect effects upon the listed organisms by, for example, perturbing
forage or prey availability, altering the extent of nesting habitat,
creating gaps in the food chain, etc.  In conducting a screen for
indirect effects, direct effect LOCs for each taxonomic group are used
to make inferences concerning the potential for indirect effects upon
listed species that rely upon non-endangered organisms in these
taxonomic groups as resources critical to their life cycle.

Because screening-level acute RQs for freshwater fish, freshwater
invertebrates, estuarine/marine invertebrates, birds, and mammals exceed
the endangered species acute LOCs, the Agency uses the dose response
relationship from the toxicity study used for calculating the RQ to
estimate the probability of acute effects associated with an exposure
equivalent to the EEC.  This information serves as a guide to establish
the need for and extent of additional analysis that may be performed
using Services-provided “species profiles” as well as evaluations of
the geographical and temporal nature of the exposure to ascertain if a
“not likely to adversely affect” determination can be made.  The
degree to which additional analyses are performed is commensurate with
the predicted probability of adverse effects from the comparison of the
dose response information with the EECs.  The greater the probability
that exposures will produce effects on a taxa, the greater the concern
for potential indirect effects for listed species dependent upon that
taxa, and therefore, the more intensive the analysis on the potential
listed species of concern, their locations relative to the use site, and
information regarding the use scenario (e.g., timing, frequency, and
geographical extent of pesticide application).

Screening-level acute RQs for aquatic invertebrates, aquatic and
terrestrial plants, birds, mammals and fish are above the non-endangered
species LOCs.  The Agency considers this to be indicative of a potential
for adverse effects to those listed species that rely either on a
specific plant species (plant species obligate) or multiple plant
species (plant dependent) for some important aspect of their life cycle.
 The Agency may determine if listed organisms for which plants are a
critical component of their resource needs are within the pesticide use
area.  This is accomplished through a comparison of Service-provided
“species profiles” and listed species location data.  If no listed
organisms that are either plant species obligates or plant dependent
reside within the pesticide use area, a no effect determination on
listed species is made.  If plant species obligate or dependent organism
may reside within the pesticide use area, the Agency may consider
temporal and geographical nature of exposure, and the scope of the
effects data, to determine if any potential effects can be determined to
not likely adversely affect a plant species obligate or dependent listed
organism.

	Aquatic Species  TC \l4 "a.	Aquatic Species 

Indirect effects to endangered/threatened fish that depend on freshwater
fish as a primary source of food, as well as larger aquatic animals that
rely on aquatic (freshwater and estuarine/marine) invertebrate
populations as a food source may occur in areas of the aldicarb
regulatory action.

	Terrestrial Species  TC \l4 "b.	Terrestrial Species 

Although RQs were not calculated for plants, aldicarb’s mode of
action, use, and open literature information (ECOTOX) showing no
terrestrial plant toxicity based on seedling emergence, this assessment
concludes that plant-dependent species will not be affected indirectly
from aldicarb use.

The Agency acknowledges that pesticides have the potential to exert
indirect effects upon endangered or threatened species, by, for example,
perturbing forage or prey availability, altering the extent of nesting
habitat, etc.  The screen for indirect effects includes using direct
effect LOCs for non-endangered species to infer the potential for
indirect effects upon listed species that rely upon non-endangered
organisms as resources critical to their life cycle.

Because at intended use rates aldicarb may cause mortality in exposed
bird and mammal populations, there are potential concerns for indirect
effects on those listed terrestrial organisms that are dependant upon
vertebrate species (birds, mammals, reptiles) as prey items. 
Additionally, indirect effects to endangered/threatened piscivorus
birds, mammals that depend on freshwater fish as a primary source of
food may occur in areas of the aldicarb regulatory action.

Aldicarb may also cause mortality in terrestrial invertebrate species
(aldicarb is highly toxic to earthworms).  Listed species dependent upon
invertebrates as a food source for all or part of their life cycle may
be indirectly affected by the loss of all or part of these populations. 
Feeding on earthworms and other terrestrial invertebrates whose bodies
contain high aldicarb levels (See section IVA3b) may also provide
substantial risk to birds and mammals.

The high acute toxicity of aldicarb to honeybees may lead to mortality
to this and other insect-pollinators.  Listed plant species dependant
upon insect pollination may be indirectly affected by the loss of all or
part of such insect populations.  Additionally, the potential risk to
bird species from aldicarb use could also affect bird-pollinated plant
species.

A potential drop in both vertebrate and invertebrate biomass associated
with aldicarb use may reduce a significant portion of the prey base.  If
this prey base is removed at a critical life-cycle juncture, over a
large area, or it if is removed for a long enough duration, some species
may have difficulty meeting energy needs.  Some species may be
particularly sensitive during reproductive or developmental periods.	

	Description of Assumptions, Uncertainties, Strengths, and Limitations 
TC \l2 "D.	Description of Assumptions, Uncertainties, Strengths, and
Limitations 

	Assumptions and Limitations Related to Exposure for all Taxa  TC \l3
"1.	Assumptions and Limitations Related to Exposure for all Taxa 

Maximum Use Scenario

This screening-level risk assessment relies on labeled statements of the
maximum rate of aldicarb application, the maximum number of
applications, and the shortest interval between applications (when
applicable).  Together, these assumptions constitute a maximum use
scenario and can overestimate risk. However, the maximum use scenario
must be considered because it is a reflection of the allowable use of 

aldicarb.

	Assumptions and Limitations Related to Exposure for Aquatic Species  TC
\l3 "2.		Assumptions and Limitations Related to Exposure for Aquatic
Species 

Lack of Averaging Time for Exposure

For an acute risk assessment, there is no averaging time for exposure. 
An instantaneous peak concentration, with a 1 in 10 year return
frequency, is assumed.  The use of the instantaneous peak assumes that
instantaneous exposure is of sufficient duration to elicit acute effects
comparable to those observed over more protracted exposure periods
tested in the laboratory, typically 48 to 96 hours.  In the absence of
data regarding time-to-toxic event analyses and latent responses to
instantaneous exposure, the degree to which risk is overestimated cannot
be quantified.

Routes of exposure

Screening-level risk assessments pesticide application for aquatic
organisms consider exposure through the gills.  Other potential routes
of exposure, not considered in this assessment, are discussed below:

Dietary consumption

The screening assessment does not consider the ingestion pathway.  This
exposure may occur through ingestion of contaminated vegetation,
invertebrates, or other exposed prey items.

Dermal exposure 

The screening assessment does not consider dermal exposure.  Dermal
exposure may occur through one potential source: contact with
contaminated water.  The available measured data related to aquatic
wildlife dermal contact with pesticides are extremely limited. 

	Assumptions and Limitations Related to Exposure for Terrestrial Species
 TC \l3 "3.	Assumptions and Limitations Related to Exposure for
Terrestrial Species 

The LD50/sq. ft. Index

The LD50/sq.ft. index was developed by Felthousen (1977).  The concept
was based upon field observations made by DeWitt (1966) who suggested
that ecological effects are expected to occur when exposure residues
that equal or exceed the LD50 value for a pesticide, as determined from
laboratory studies, are reached in the field.  The index was developed,
in response to the Registration Divisions’ request for guidance for
classifying use patterns,  involving granulated formulations, baits, and
seed treatments, for labeling purposes.  At that time risk criteria
considerations were typically based on the amount of residues likely to
occur, immediately following application, in or on feed items likely to
be consumed by non-target wildlife species. In so much as granular
formulations, baits and seed treatments  leave very little residue in or
on non-target food items,  a hazard index had to be developed to address
theses routes of exposure. It’s important to note that the LD50/sq.
ft. concept is an index to hazard that presumes exposure will occur on
the treated areas (a deterministic assessment) rather than a tool that
attempts to quantify the temporal and spatial relationship of exposure
(i.e., a probabilistic assessment tool) to a non-target organism.  

The LD50/sq.ft. index used to predict risk to non-target wildlife
species has been peer reviewed by numerous scientists, both within and
outside of the Agency and, in general, has been accepted as a useful
tool for addressing ecological hazard from the use of granulated 
formulations.  In March of 1992, the Agency used this index in its
“Comparative Analysis of Acute Avian Risk from Granular Pesticides”
document.  This document provided explanation, discussion and analysis
of the index as well as specific examples of risk quotients derived from
the index.  In 1996 the FIFRA Science Advisory Panel (SAP) reviewed and
approved the environmental assessments derived from the index for those
chemicals evaluated in the corn cluster document.  The SAP even
suggested that the acute risk indices calculated from the index may
actually underestimate risk.  Again, in January of 1998 , in reviewing
the Carbofuran Technical Support Document 1 , the SAP supported the risk
index as an acceptable initial approach to characterize avian risk and
as a useful indication of potential risks of granular pesticides to
birds. 

Based on this long history of scientific peer review, which has
repeatedly supported the use of the LD50/sq. ft. risk index in
ecological hazard assessments, we believe that the index is appropriate
for determining and classifying  ecological risk to terrestrial wildlife
from the use of granular formulations.  

Uncertainties Associated with the LD50/sq. ft. Index

Risk quotients based on the LD50/sq.ft. hazard index have been
criticized as being too conservative and overestimating “real world”
risk.  It has been argued that the method greatly oversimplifies the
exposure component to hazard assessment by not specifically addressing
the temporal and spatial situations  that non-target wildlife species
experience under field conditions. Although this is somewhat correct
there are still many other exposure related and toxicological factors
that are not accounted for by the index which may actually underestimate
risk from this method.  

For example, the LD50/sq.ft. index is based solely on acute mortality as
derived from acute oral exposure from laboratory tests.  It does not
address subacute behavioral or physiological effects that may occur
prior to mortality and yet can still have a profound sub-lethal effects
on an organisms ability to survive and reproduce. As such, this index
may underestimate ecological hazard from sub-lethal exposures.  For
instance, it is common in clinical observations,  conducted during acute
tests, to observe such symptoms as wing droop, goose-stepping ataxia,
dyspnea (labored breathing), diarrhea, apnea, weight loss, salivation,
convulsions and hyperactivity prior to mortality occurring.  Even if an
organism survives this exposure to the toxicant, these symptoms indicate
the organism is under extreme stress that could greatly affect both its
survival (susceptibility to disease and parasites, ability to avoid
predation, nest desertion and abandonment) and ability to reproduce
under actual field conditions.  Necropsy data also indicate that many
organisms are experiencing extreme physiological changes even though
they may not die from exposure to the toxicant. Liver damage, renal
failure, lesions, hemorrhage and other tissue damage are indications of
severe physiological impairment that could adversely affect both the
survival and reproductive capability of the organisms.  These sub-lethal
effects are not really addressed by the LD50/sq. ft. index.  In fact,
although the SAP (1996) approved the LD50/sq.ft. index as a method for
determining and classifying  ecological risk to terrestrial wildlife
from the use of granular formulations, it questioned the use of
mortality as the primary end-point for addressing ecological risk. The
SAP stated that, “Many chemicals evoke toxicity through the
interference with the physiological state of the animal including
behaviors important to continued reproduction and survival.  Each
chemical may have certain unique qualities that may influence their
potential hazard to wildlife.”  These comments suggest that basing
ecological hazard assessments solely on direct effects, as determined by
acute indices,  may be under protective for predicting indirect effects
from sub-lethal exposures.  

The systemic nature of aldicarb, especially the major degradates which
are also highly toxic to non-target wildlife, is another exposure factor
that is not accounted for by the LD50/sq.ft. hazard index.  For
instance, to be efficacious, aldicarb must translocate, via the root
system to those portions of the plant that are likely to be attacked by
the pest species.  Non-target organisms feeding on these plant parts
(and/or other non-crop plant species that have been exposed to
treatment)  are now exposed to subacute dietary concentrations of the
pesticide,  as well as acute exposure from feeding directly on the
granules. Whether or not this will result in an increase in total body
burden residues is unknown but it definitely increases the routes of
exposure.

Although it is presumed that the LD50/sq.ft. index accounts for acute
exposure from oral, dermal and inhalation exposure, it was not intended
to address exposure from drinking water where runoff, from either rain
events or irrigation, to low areas may create puddles that contain very
high concentrations of the pesticide.  The contribution of this route of
exposure to overall body burden residues is unknown but it will clearly
be additive to exposure from direct consumption of the granules and/or
exposure from eating contaminated vegetation.

The Likelihood of Wildlife Presence at Time of Application 

Birds and mammals may utilize fields that have been treated with
aldicarb and therefore may be exposed.  Birds have been seen feeding in
fields during planting.  This may be due to the invertebrates and seeds
brought to the surface by tillage.  Also, birds and mammals foraging for
seeds, insects, and annelids (e.g., earthworms) may be unable to avoid
ingesting granular aldicarb.  Birds may also ingest granules in treated
areas when foraging for grit.

Significance of Wildlife Utilization of Crop Fields

Characterizing risk to non-target wildlife from the use of aldicarb on
the numerous crops in which it is registered, requires a clear
understanding of the many limitations of identifying exactly what
species are most likely to use treated fields and for what purpose. The
ultimate value of agricultural croplands to terrestrial wildlife
species, depends greatly on the suitability of these “managed
ecosystems” to simultaneously satisfy a species temporal and spatial
habitat requirements.  In fact, in many areas of the United States where
farming and/or ranching is extensive, agricultural croplands provide the
only suitable habitat for many species of wildlife.  Although numerous
avian (e.g., upland game birds, waterfowl, songbirds and shorebirds) and
mammalian (e.g., small mammals to large ungulates) species utilize
agricultural croplands for loafing, feeding , nesting, cover, breeding 
and escape habitats (Gusey and Maturgo, 1973), such utilization greatly
depends on numerous biotic and abiotic factors, and how they interact to
satisfy both the daily and/or seasonal habitat requirements for the
particular species utilizing these areas.  For instance, resident
species probably utilize croplands to a greater extent than migratory
species because they are reproducing their young in or near agricultural
fields.  There can even be a large variation in use patterns among
resident species depending on the areas suitability to meet the specific
survival and reproduction for each of the species.  However,  there may
be times when these same croplands are just as useful and crucial to the
survival of migratory species as they are to resident species in that
they provide critical resting, “stop-over” and/or “staging”
areas along their migration route. The simple fact is, wildlife
utilization of agricultural areas is highly variable and difficult to
predict and, as such, there is a great deal of uncertainty surrounding
this issue when conducting an ecological hazard evaluation.

Routes of Exposure

Screening-level risk assessments for pesticides consider dietary
exposure alone.  Other routes of exposure, not considered in this
assessment, are discussed below:

Incidental soil ingestion exposure

This risk assessment does not consider incidental soil ingestion. 
Available data suggests that up to 15% of the diet can consist of
incidentally ingested soil depending on the species and feeding strategy
(Beyer et al., 1994).  A simple first approximation of soil
concentration of pesticide shows the effect of not considering
incidental soil ingestion:

Assuming the maximum application rate of aldicarb of 10.0 lb/acre (11.2
kg/ha) to a bare, very low density soil (1 g/cm3) incorporated to 3
inches (7.62 cm - the most commonly label-specified soil incorporation
depth, the aldicarb soil concentration at a depth of 7.62 cm is:

 

Including this concentration into the standard screening-level method
and assumptions for food item pesticide residues shows that ingestion of
soil at an incidental rate of up to 15% of the diet would increase
dietary exposure.

Dermal Exposure

The screening assessment does not consider dermal exposure, except as it
is indirectly included in calculations of RQs based on lethal doses per
unit of pesticide treated area.  Dermal exposure may occur through two
potential sources: (1) incidental contact with contaminated vegetation,
or (2) contact with contaminated water or soil.

The available measured data related to wildlife dermal contact with
pesticides are extremely limited.  The Agency is actively pursuing
modeling techniques to account for dermal exposure via incidental
contact with vegetation.

Drinking Water Exposure

Drinking water exposure to a pesticide active ingredient may be the
result of consumption of surface water or consumption of the pesticide
in dew or other water on the surface of treated soil.  For pesticide
active ingredients with a potential to dissolve in runoff, puddles on
the treated field may contain the chemical.  Given its high water
solubility, aldicarb is expected to dissolve in dew and other water
associated with plant surfaces. However, the likelihood of exposure to
aldicarb via drinking water is not quantified in the exposure modeling.

Incidental Pesticide Releases Associated with Use

This risk assessment is based on the assumption that the entire
treatment area is subject to aldicarb application at the rates specified
on the label.  In reality, there is the potential for uneven application
of aldicarb through such plausible incidents as changes in calibration
of application equipment, spillage, and localized releases at specific
areas of the treated field that are associated with specifics of the
type of application equipment used.

	Assumptions and Limitations Related to Effects Assessment  TC \l3 "4.
Assumptions and Limitations Related to Effects Assessment 

Age class and sensitivity of effects thresholds

It is generally recognized that test organism age may have a significant
impact on the observed sensitivity to a toxicant.  The screening risk
assessment acute toxicity data for fish are collected on juvenile fish
between 0.1 and 5 grams.  Aquatic invertebrate acute testing is
performed on recommended immature age classes (e.g., first instar for
daphnids, second instar for amphipods, stoneflies and mayflies, and
third instar for midges).  Similarly, acute dietary testing with birds
is also performed on juveniles, with mallard being 5-10 days old and
quail 10-14 days old.

Testing of juveniles may overestimate toxicity at older age classes for
pesticidal active ingredients, such as aldicarb, that act directly 
because younger age classes may not have the enzymatic systems
associated with detoxifying xenobiotics.  The screening risk assessment
has no current provisions for a generally applied method that accounts
for this uncertainty.  In so far as the available toxicity data may
provide ranges of sensitivity information with respect to age class, the
risk assessment uses the most sensitive life-stage information as the
conservative screening endpoint.

Additional Lines of Evidence for Aldicarb Toxicity

Terrestrial Studies

Several studies obtained through ECOTOX suggest that mammalian aldicarb
exposure may lead to changes in sublethal endpoints.  Yarsan et al.
(1999) demonstrated a significant decrease in Cu-Zn superoxide disumtase
activity in Swiss albino mice following subacute (15d), subchronic
(45d), and chronic (120d) dietary aldicarb exposure (0.3 - 1.2 mg/kg
body weight).  Additionally, a significant decrease in glutathione
peroxidase was seen in these mice following subchronic and chronic
aldicarb exposure.  These results suggest that aldicarb may decrease the
antioxidant capacity in mammals, leaving the animals  to cellular
oxidative damage, such as cellular membrane damage (e.g., lipid
peroxidation).  

A study by Wei et al., (1997) demonstrated and induction of micronuclei
in both in vitro and in vivo mammalian systems exposed to aldicarb. 
Both Chinese hamster ovary cells (CHO) and BALB/c mice exposed to
aldicarb showed increases in micronuclei and mouse bone marrow
micronucleated reticulocytes, respectively.  These results suggest the
potential for aldicarb-induced genotoxic damage, although these results
are preliminary. 

Aquatic Studies

Several endpoints that are not survival, growth, or reproductive
endpoints were identified for aquatic organisms.  Pant et al.(1987) also
studied hematological and biochemical effects on the rosy barb, Puntius
conchonius exposed to a commercial formulation of aldicarb.  Chronic
aldicarb exposure caused moderate polycythemia, increase in hemoglobin
content, lowered blood glucose levels, and increase in liver and ovary
cholesterol.  Gill et al. (1991) found similar adverse effects of
aldicarb on the rosy barb, Puntius conchonius.  Circulating populations
of leucocytes, erythrocytes, and hemoglobin content were chosen as
parameters after 4 week exposures to sublethal concentrations of
aldicarb. Aldicarb caused statistically significant (P<0.05)
polycythemia and an increase in hemoglobin content.  An increase in
large lymphocyte populations and small lymphocyte counts were observed. 
Overall, the exposed fish would suffer from immunosuppression causing
decreased disease and parasite resistance, inability to secure and
assimilate food for basal energy requirements, lack of physical strength
to escape predators, and physiological impairments affecting vital
processes.

Use of the Most Sensitive Species Tested

Although the screening-level risk assessment relies on a selected
toxicity endpoint from the most sensitive species tested, it does not
necessarily mean that the selected toxicity endpoints reflect
sensitivity of the most sensitive species existing in a given
environment.  The relative position of the most sensitive species tested
in the distribution of all possible species is a function of the overall
variability among species to a particular chemical.  In the case of
listed species, there is uncertainty regarding the relationship of the
listed species’ sensitivity and the most sensitive species tested.

The Agency is not limited to a base set of surrogate toxicity
information in establishing risk assessment conclusions. The Agency also
considers toxicity data on non-standard test species when available.

	Assumptions Associated with the Acute LOCs  TC \l3 "5.	Assumptions
Associated with the Acute LOCs 

The risk characterization section of the assessment document includes an
evaluation of the potential for individual effects at an exposure level
equivalent to the LOC.  This evaluation is based on the median lethal
dose estimate and dose/response relationship established for the effects
study corresponding to each taxonomic group for which the LOCs are
exceeded.  

The avian T-REX default scaling factor (based on the slope of the
regression of Log (LD50) against Log (weight)) of 1.15 was used in the
RQ calculations (see above equation) to adjust for size-influenced
sensitivity (e.g., smaller birds are more sensitive to aldicarb toxicity
than larger birds).  However, research by Mineau et al. (1996) suggests
that the scaling factor for aldicarb should be 1.4, rather than 1.15. 
Substituting the aldicarb-specific scaling factor of 1.4 into the above
avian equation results in RQ values as high as 22,000 (20g bird, maximum
cotton application rate).  It is therefore possible that the RQ
calculations presented in this risk assessment are underestimated.  

	Data Gaps and Limitations of the Risk Assessment  TC \l3 "6.	Data Gaps
and Limitations of the Risk Assessment 

The following data gaps were identified:

Ecotoxicity Data Gaps

	71-4(a) Avian Reproduction - Quail

	71-4(b) Avian Reproduction - Duck

	121-1(a)	Seedling Emergence - 10 species

	121-1(b)	Vegetative Vigor - 10 species

	122-2		Aquatic Plant Growth - 5 species

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