United States     Prevention, Pesticides   EPA-738-R-06-031
           Environmental Protection  And Toxic Substances   August 2006
           Agency       (7508P)
xvEPA
          Interim Reregistration
          Eligibility Decision
          Carbofuran
                 List [A]

              Case No. 0101

-------
Interim Reregistration Eligibility Decision (IRED)
Document for Carbofuran
Approved by:  Debra Edwards, Ph. D.
             Director
             Special Review and Reregistration Division
Date:         August 3, 2006

-------
                             Table of Contents

Carbofuran Interim Reregi strati on Eligibility Decision Team	i
Glossary of Terms and Abbreviations	ii
I.   Introduction	1
II.     Chemical Overview	2
  A.   Regulatory History	2
  B.   Chemical Identification	3
  C.     Use Profile	4
  D.   Estimated Usage of Pesticide	5
III.     Summary of Carbofuran Risk Assessments	5
  A.   Human Health Risk Assessment	5
    1.   Toxicity of Carbofuran	5
    2.   Dietary Exposure and Risk from Food and Water	9
    3.   Residential and Other Non-occupational Risk	12
    4.   Aggregate Exposure and Risk	12
    5.   Occupational Exposure and Risk	13
    6.   Smoker Assessment	17
    7.   Human Incident Data	17
  B.   Environmental Risk Assessment	18
    1.   Environmental Fate and Transport	20
    2.   Ecological Risk Estimation	20
       a.   Terrestrial Organisms	20
         i)   Birds	20
         ii)  Mammals	22
         iii)    Non-target insects	23
       b.   Aquatic Organisms	24
         i)   Freshwater and Estuarine/Marine Fish	25
         ii)  Freshwater and Estuarine/Marine Invertebrates	26
    3.   Risk Characterization	28
    4.   Endangered Species Considerations	29
IV.     Interim Risk Management, Reregi strati on, and Tolerance Reassessment Decision
       29
  A.     Determination of Reregi strati on  Eligibility	29
  B.   Public Comments and Responses	30
  C.   Regulatory Position Under FIFRA  and FFDCA	30
    1.   Mitigation Summary	31
    2.   Regulatory Rationale	31
    3.   Significance  of Use	33
  D.   Endangered Species Considerations	35
  E.   Food Quality Protection Act Findings and Tolerance Summary	36
    1.   FQPA	36
       a.   Risk Cup Determination	36
       b.   Endocrine Disrupter Effects	37
    2.   Interim Tolerance Summary	37

-------
Carbofuran Interim Reregistration Eligibility Decision Team

Office of Pesticide Programs:

Biological and Economic Analysis Assessment

David Brassard
Angel Chiri
David Donaldson
Jin Kim
Andrew Lee
Stephen Smearman
TJ Wyatt
Nicole Zinn

Environmental Fate and Effects Risk Assessment

Edward Fite
Edward Odenkirchin
Melissa Panger
Donna Randall
Christopher Salice
Dirk Young

Health Effects Risk Assessment

Danette Drew
John Liccione
Susan Stanton
Stephen Weiss

Registration Support

JAita Kumar

Risk Management

Stephanie Plummer
Laura Parsons

-------
Glossary of Terms and Abbreviations
AGDCI
ai
aPAD
AR
BCF
BMD
CFR
cPAD
CSF
CSFII
DCI
DEEM
EC
EDWC
EEC
EPA
EUP
FCID
FDA
FIFRA
FFDCA
FQPA
FOB
G
GENEEC
GLN
HAFT
IR
LCso
LD50
LOC
LOD
LOAEL
MATC
Og/L
mg/kg/day
Agricultural Data Call-In
Active Ingredient
Acute Population Adjusted Dose
Anticipated Residue
Bioconcentration Factor
Benchmark Dose
Code of Federal Regulations
Chronic Population Adjusted Dose
Confidential Statement of Formula
USDA Continuing Surveys for Food Intake by Individuals
Data Call-In
Dietary Exposure Evaluation Model
Emulsifiable Concentrate Formulation
Estimated Drinking Water Concentration
Estimated Environmental Concentration
Environmental Protection Agency
End-Use Product
Food Commodity Intake Database
Food and Drug Administration
Federal Insecticide, Fungicide, and Rodenticide Act
Federal Food,  Drug, and Cosmetic Act
Food Quality Protection Act
Functional Observation Battery
Granular Formulation
Tier I  Surface Water Computer Model
Guideline Number
Highest Average Field Trial
Index  Reservoir
Median Lethal Concentration.  A statistically derived concentration
of a substance that can be expected to cause death in 50% of test
animals.  It is usually expressed as the weight of substance per
weight or volume of water, air or feed, e.g., mg/1, mg/kg or ppm.
Median Lethal Dose.  A statistically derived single dose that can be
expected to cause death in 50% of the test animals when
administered by the route indicated (oral, dermal, inhalation). It is
expressed as a weight of substance per unit weight of animal, e.g.,
mg/kg.
Level  of Concern
Limit  of Detection
Lowest Observed Adverse Effect Level
Maximum Acceptable Toxicant Concentration
Micrograms Per Gram
Micrograms Per Liter
Milligram Per Kilogram Per Day
                                      11

-------
mg/L
MOE
MRID

MUP
NA
NAWQA
NPDES
NR
NOAEL
OP
OPP
OPPTS
PAD
PCA
PDF
PHED
PHI
ppb
PPE
ppm
PRZM/EXAMS
Qi*

RAC
RED
REI
RfD
RQ
SCI-GROW
SAP
SF
SLC
SLN
TAP
TCPSA
TGAI
TRR
USDA
USGS
UF
UV
WPS
Milligrams Per Liter
Margin of Exposure
Master Record Identification (number). EPA's system of recording
and tracking studies submitted.
Manufacturing-Use Product
Not Applicable
USGS National Water Quality Assessment
National Pollutant Discharge Elimination System
Not Required
No Observed Adverse Effect Level
Organophosphate
EPA Office of Pesticide Programs
EPA Office of Prevention, Pesticides and Toxic Substances
Population Adjusted Dose
Percent Crop Area
USDA Pesticide Data Program
Pesticide Handler's Exposure Data
Preharvest Interval
Parts Per Billion
Personal Protective Equipment
Parts Per Million
Tier II Surface Water Computer Model
The Carcinogenic Potential of a Compound, Quantified by the
EPA's Cancer Risk Model
Raw Agriculture Commodity
Reregi strati on Eligibility Decision
Restricted Entry Interval
Reference Dose
Risk Quotient
Tier I Ground Water Computer Model
Science Advisory Panel
Safety Factor
Single Layer Clothing
Special Local Need (Registrations Under Section 24(c) of FIFRA)
Toxicity Adjustment Factor
2,3,3-trichloroprop-2-ene sulfonic acid (nitrapyrin Metabolite)
Technical Grade Active Ingredient
Total Radioactive Residue
United States Department of Agriculture
United States Geological  Survey
Uncertainty Factor
Ultraviolet
Worker Protection Standard
                                      in

-------
I.      Introduction

       The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was amended
in 1988 to accelerate the reregi strati on of products with active ingredients registered prior
to November 1, 1984.  The amended Act calls for the development and submission of
data to support the reregi strati on of an active ingredient, as well as a review of all
submitted data by the U.S. Environmental Protection Agency (hereafter referred to as
EPA or the Agency). Reregi strati on involves a thorough review of the scientific database
underlying a pesticide's registration.  The purpose of the Agency's review is to reassess
the potential risks arising from the currently registered uses of the pesticide, to determine
the need for additional data on health and environmental  effects, and to determine
whether or not the pesticide meets  the "no unreasonable adverse effects" criteria of
FIFRA.

       On August 3, 1996, the Food Quality Protection Act of 1996 (FQPA) was signed
into law.  This Act amends FIFRA to require reassessment of all tolerances in effect on
the day before it was enacted by August 2006.  EPA decided that, for those chemicals
that have tolerances and are undergoing reregi strati on, tolerance reassessment will be
accomplished through the reregi strati on process.  FQPA also amended the Federal Food,
Drug, and Cosmetic Act (FFDCA) to require a safety finding in tolerance reassessment
based on factors that include an assessment of cumulative effects of chemicals with a
common mechanism of toxicity. The reason for consideration of other substances is that
the possibility exists that low-level exposures to multiple chemicals that cause a common
toxic effect lead to the same adverse health effect as would a high level of exposure to
any one of the other substances individually.

       As mentioned above, FQPA requires EPA to consider "available information"
concerning the cumulative effects of a particular pesticide's residues and "other
substances that have a common mechanism of toxicity" when considering whether to
establish, modify, or revoke a tolerance. Carbofuran is a member of the N-methyl
carbamate (NMC) class of pesticides. This class also includes carbaryl, aldicarb,
methomyl, and oxamyl, among others.  The NMCs, as a group, have been determined to
share a common mechanism of toxicity (July 2001 memo from Office Director Marcia
Mulkey).  The preliminary cumulative risk assessment (CRA) for the NMC cumulative
Assessment Group, which includes carbofuran, was released in July 2005.  The revised
CRA is currently being developed  and will be completed during 2006.  The results of this
NMC cumulative  assessment, as well as the single chemical carbofuran assessment, will
be considered during the carbofuran reregi strati on process in which decisions regarding
establishing, modifying, or revoking carbofuran tolerances will be made.

    This document presents EPA's revised human health and ecological risk assessments
and its progress toward tolerance reassessment, and the interim reregi strati on eligibility
decision for carbofuran.  The document consists of six sections: section I contains the
regulatory framework for reregi strati on/tolerance reassessment; section II provides a
profile of the use and usage  of the chemical; section III gives  an overview of the revised

-------
human health and environmental effects risk assessments based on data, public
comments, and other information received in response to the preliminary risk
assessments, section IV presents the Agency's reregi strati on eligibility, tolerance
reassessment, and risk management decisions; section V summarizes label changes
necessary to implement the risk mitigation measures outlined in Section IV; and section
VI provides information on how to access related documents. Finally, the Appendices
list related and supporting documents and Data Call-In (DCI) information. The revised
risk assessment documents and related addenda are not included in this document, but are
available in the Public Docket under  docket number EPA-HQ-OPP-2005-0162.

II.     Chemical Overview

       A.     Regulatory History

       Carbofuran is a broad spectrum N-methyl carbamate insecticide and nematicide
registered for control of soil and foliar pests on a variety of field, fruit, and vegetable
crops.  It was first registered in the United States in 1969.  Through an agreement
between EPA and the technical registrant in 1991, granular carbofuran has been limited
to the sale of 2,500 Ibs of active ingredient per year in the U.S. since  1994, for use only
on certain crops.  Today granular carbofuran is limited to use on spinach grown for seed,
pine seedlings, bananas (in Hawaii only), and cucurbits  only.  Carbofuran is classified as
a restricted use pesticide.

       In the late 1990s, the technical registrant made a number of changes to labels in
order to reduce drinking water and ecological risks of concern.  These included reducing
application rates  and numbers of applications for alfalfa, cotton, corn, potatoes, soybeans,
sugarcane, and sunflowers. Numbers of applications were also restricted on some soils to
reduce groundwater concentrations.

       Three human studies have been conducted for carbofuran - one oral and two
dermal. Since the 1990s, the Agency has considered the appropriateness of these studies
for risk assessment purposes several times. Most recently, these studies were reviewed
by the Agency's  Human Studies Review Board (HSRB) in May 2006. The HSRB
concluded that, while informative, the studies are not  appropriate for  use by the Agency
in either the individual carbofuran or N-methyl carbamate cumulative risk assessment.
This decision was based upon the following, for all three studies:  small sample size, lack
of control subjects, and highly variable results for  red blood cell cholinesterase activity.
Additionally,  the board had concerns regarding inappropriate application methods in the
dermal studies and also determined that the conduct of the dermal studies was unethical.

       There are currently one technical, two manufacturing-use,  and six end-use
products  registered under Section 3 of the Federal  Insecticide, Fungicide and Rodenticide
Act (FIFRA).  There are also 77 active Special Local Need registrations under Section
24(c) of FIFRA.  This Interim Reregi strati on Eligibility Decision document evaluates
risks from all currently registered uses.

-------
       EPA followed a 6-phase public participation process in developing this interim
decision. This means that there were two 60-day public comment periods on the risk
assessments. EPA released the revised human health and ecological risk assessments for
the second phase of public comment (Phase 5) on March 22, 2006. This IRED document
will be posted in the carbofuran reregi strati on docket, along with any revised risk
assessments and responses to public comments received.
       B.
Chemical Identification
Chemical Structure:
                 0
                       CH,
   0 ,.    _0
      _.NH
 H3C
Common Name: Carbofuran

Chemical Name: 2,3-dihydro-2,2-dimethyl-7-benzofuranyl-N-methylcarbamate

Chemical Family:  N-methyl Carbamate

Empirical Formula:  C^HisNOs

CAS Registry Number:     1563-66-2

Case Number:             0101
OPP Chemical Code:

Molecular weight:

Trade Names:

Basic Manufacturers:
             090601

             221.3

             Furadan

             FMC Corporation
       Carbofuran is an odorless, white, crystalline solid with a melting point range of
150-154 ° C. It is slightly soluble in water, and is highly soluble in N-methyl-2-
pyrrolidone, dimethylformamide, dimethyl sulfoxide, acetone, acetonitrile, methylene

-------
chloride, cyclohexanone, benzene, and xylene.  Carbofuran is stable under neutral and
acidic conditions, but decomposes under alkaline conditions.

       C.     Use Profile

       The following is information on the currently registered uses of carbofuran,
including an overview of use sites and application methods.

Type of Pesticide:         Restricted use systemic insecticide

Summary of Use:         Used for control of a variety of insect pests on a variety of
                          field, fruit, and vegetable crops.  Carbofuran is not used in
                          residential settings or food-handling establishments.

Food uses:                 Registered for use on the following crops/sites:

Alfalfa, artichoke, banana, barley, coffee, corn (field, pop, and sweet), cotton, cucurbits
(cucumber, melons, and squash), grapes, oats, pepper, plantain, potato, sorghum,
soybean, sugar beet, sugarcane, sunflower,  and wheat

Non-food uses:

Agricultural fallow land, cotton, ornamental and/or shade trees, ornamental herbaceous
plants, ornamental non-flowering plants, ornamental woody shrubs and vines, pine,
spinach grown for seed, and tobacco

Target Pests:              Alfalfa weevil, aphids, banana root borer, Colorado potato
                           beetle, corn rootworm, cribrate weevil, cucumber beetles,
                           European corn borer, flea beetles, grasshoppers,
                           leafhoppers, nematodes, potato tuberworms, Southwestern
                           corn borer, thrips, wireworms

Formulation Types:        Granular and flowable
Method and Rates of Application:

Application Methods:              Foliar, soil, seedling dip

Application Equipment:            Aerial equipment, chemigation systems,
                                  groundboom sprayers, airblast sprayers, tractor-
                                  drawn spreaders, and handheld equipment.

Application Rates:                 Application rates range from 0.19 (agricultural
                                  fallow land) to 10 Ibs a.i./A (grapes and potatoes),
                                  depending on the application scenario.

-------
Application Timing:
Use Classification:
                    At plant, post-plant

                    Restricted
       D.    Estimated Usage of Pesticide

       The estimate for total domestic use (annual average) of carbofuran is nearly 1
million pounds of active ingredient for the liquid formulation, with the majority of use
occurring on the following crops: corn, alfalfa, and potatoes. Under the existing terms
and conditions of the registration, sale of the granular formulation is limited to 2,500
pounds active ingredient per year, and use is limited to pine seedlings, cucurbits, bananas
(in Hawaii only), and spinach grown for seed.
III.
Summary of Carbofuran Risk Assessments
       The purpose of this summary is to assist the reader by identifying the key features
and findings of these risk assessments, and to help the reader better understand the
conclusions reached in the assessments. The human health and ecological risk
assessments form the basis of interim regulatory decisions for carbofuran. While the risk
assessments and related addenda are not included in this document, they are available
from the OPP Public Docket EPA-HQ-OPP-2005-0261 and may be accessed on the
internet at http://www.regulations.gov.
       A.
Human Health Risk Assessment
              1.     Toxicity of Carbofuran

Table 1. Acute Toxicity of Carbofuran
Guideline No./ Study Type
870. 1 100 Acute oral toxicity
870.1200 Acute dermal
toxicity
870 . 1 3 00 Acute inhalation
toxicity
870.2400 Acute eye irritation
870.2500 Primary dermal
irritation
870.2600 Skin sensitization
Species
Rat
Rabbit
Rat
Rabbit
Rabbit
Guinea
Pig
MRID No.
Gronning and
Kimmerle, 1974
44671601
Gronning and
Kimmerle, 1974
00070347
00054336
44827101
Results
LD50 = 7.8 mg/kg _
6.0 mg/kg
LD50 = 4403 (2900 - 6685)
mg/kg - intact skin
LC50 = 0.08 mg/L
Minimal irritation
Primary Irritation Score =
0.25
Non sensitizer
Toxicity
Category
I
III
I
III
IV
N/A

-------
       Animal toxicity studies show that, as with other N-methyl carbamate pesticides,
the critical effect of carbofuran for various exposure durations is cholinesterase
inhibition. Similar to other N-methyl carbamate pesticides, inhibition is followed by
rapid recovery of cholinesterase.

       The toxicology database is considered to be adequate for selection of endpoints
for risk assessment.

       EPA considered a human oral study as part of its deliberations; however, due to
serious scientific limitations, EPA has not included it in the carbofuran risk assessment
that supports the reregi strati on decision outlined in this document.  The results of the rat
comparative ChE study are considered to be the most suitable for risk assessment
purposes.

       Developmental toxicity studies in both the rat and rabbit show no evidence of
quantitative or qualitative increased susceptibility of the developing fetuses. There was
evidence of qualitative increased susceptibility in the rat multi-generation reproduction
study since offspring toxicity was manifested as decreased pup survival between birth
and post natal day (PND) 4, whereas parental toxicity was limited to decreased body
weight gain.

       The rat developmental neurotoxicity study also provided  evidence of a qualitative
increase in offspring susceptibility.  At the lowest observed adverse effects level
(LOAEL) of 75 ppm, maternal toxicity was manifested as decreased body weight gain
and food consumption, whereas offspring toxicity at this dose was manifested as
increased mortality, decreased pup viability, and decreased fetal weight.

       Carbofuran is primarily metabolized into three phenolic carbamate metabolites
and into 3-hydroxy carbofuran.  The trio of phenolic metabolites is not deemed to be of
toxicological significance. For risk assessment purposes, 3-hydroxy carbofuran is
considered to be of equal toxicity as parent carbofuran.

FOP A Safety Factor

       The FQPA Safely Factor (as mandated by the Food Quality Protection Act of
1996) is intended to provide up to an additional 10-fold safety factor (10X), to account
for potential pre- and post-natal toxicity and completeness of the data with respect to
exposure (food, water, and non-occupational) and toxicity to infants and children.  In the
case of carbofuran, there was no evidence of either quantitative or qualitative increased
susceptibility of fetus/pups in the rat or rabbit developmental toxicity studies.  There was
evidence of qualitative increased susceptibility in the rat multi-generation reproduction
study and the rat developmental neurotoxicity study. BMD (benchmark dose) analyses of
the comparative  ChE rat study revealed that the BMD values for the PND11 pups were
lower (i.e., more sensitive) than those of adult rats.  The Agency has retained a FQPA
factor (for database uncertainties) in the derivation of the carbofuran acute PAD, which is
based on brain ChE inhibition in rat pups.  The magnitude of this factor is 5X. This

-------
factor was based on the following rationale: the comparative ChE rat study measured
only brain ChE inhibition, red blood cell (RBC) ChE inhibition in adult rats is the more
sensitive endpoint; there is an observed 5-fold difference between brain ChE inhibition
and RBC ChE inhibition in adult rats; and the assumption is made that for rat pups, there
will be a similar 5-fold difference in RBC vs. brain ChE inhibition. See also the
discussion below under "Endpoints selected for risk assessment."

Cancer Classification

       Carbofuran does not appear to possess mutagenic activity and was negative in
both rat and mouse oncogenicity assays.  Carbofuran is classified as a "Not likely" human
carcinogen based on the lack of evidence of carcinogenicity in mice or rats.

Endpoints selected for risk assessment

       There are several studies available which measured  acute ChE inhibition at or
near the peak time of inhibition (15 to 45 minutes), and which the Agency was able to use
to determine the derivation of the acute RfD and acute PAD. These include two studies
performed by the registrant:   1) a time course study in which male and female rats were
dosed at 0.5 and 1.0 mg/kg,  and 2) a comparative ChE study where adult and juvenile
(PND11) rats were dosed at  0.3, 0.6, and  1.0 mg/kg.  A third ChE  study was performed in
support of the Agency's cumulative risk assessment for the N-methyl carbamates. In this
study, scientists from the USEPA National Health and Environmental Effects Research
Laboratory (NHEERL)  performed dose-response studies in male rats, where brain and
RBC ChE inhibition,  along with motor activity, were measured. This study included
doses of carbofuran ranging from 0.1 mg/kg to 1.5 mg/kg.

       The risk assessment for carbofuran is based on BMD values, rather than No
Observed Adverse Effect Level (NOAEL) or LOAEL values. The Agency used this
method because NOAELs and LOAELs do not necessarily  offer the best characterization
between dose and response for a given chemical, and are often limited by dose selection.
In order to evaluate the  appropriate point of departure (PoD) for ChE inhibition, EPA
performed a BMD analysis using the available comparative cholinesterase study in rats
(the most sensitive species).

       The dose at which 10% ChE inhibition is observed (BMDio) and the lower 95%
confidence intervals (BMDLio) were estimated from the comparative cholinesterase
study.  The BMDio was selected because it is generally at or near the limit of sensitivity
for discerning a statistically  significant decrease in ChE activity across the blood and
brain compartments, and is a response level close to the background ChE. Moreover, the
Agency believes that  10% is likely to be protective to other toxicities, such as clinical
signs and/or behavioral  endpoints.

       The BMDLio  of 0.03 mg/kg/day for inhibition of ChE in the brain of PND11 male
pups was selected for derivation of the acute RfD. The following uncertainty factors
were applied:  5X FQPA safety factor based on database uncertainties, 10X for variability

-------
      among individuals, and 10X for interspecies extrapolation.  The resulting aPAD for the
      general population and all population subgroups is 0.00006 mg/kg/day.

              The Agency's analysis of the brain ChE inhibition data from the comparative
      ChE study suggests that PND 11 pups are 2.5X more sensitive than adults (0.11 mg/kg
      and 0.12 mg/kg for male and female adult rats, respectively, as compared to 0.04 mg/kg
      and 0.05 mg/kg for male and female PND11 rats, respectively).  In addition, the
      following uncertainties exist: 1) RBC ChE inhibition may be a more sensitive endpoint
      compared to brain ChE; 2) pups appear to be more sensitive than adult rats; and 3) due to
      the lack of reliable RBC data in pups, there is residual uncertainty in the available
      toxicology database.  Given these uncertainties, the Agency has retained a 5X FQPA
      safety factor in the derivation of the carbofuran acute RfD.  Due to the fact that the RfD
      is based on a BMDLio in rat pups, there is no need to account for the  2.5X sensitivity
      observed in pups vs.  adults.

              A chronic RfD was not selected because the acute RfD  is considered protective
      of chronic exposures, given that carbofuran-induced inhibition of ChE activity is
      reversible (within 24 hours). The longer-term exposures could be considered a series of
      acute exposures.

Table 2. Toxicity Endpoints for Human Health Risk Assessment for Carbofuran	
      Exposure
       Scenario
    Dose Used in Risk
      Assessment,
          UF
                  FQPA SF and Endpoint
                   for Risk Assessment
   Study and Toxicological Effects
Acute Dietary
All Populations
BMDL10 = 0.03 mg/kg/day
       UF = 500
  Acute RfD = 0.00006
       mg/kg/day
                     FQPA SF = 5X

                     aPAD = 0.00006
                       mg/kg/day
Comparative ChE Study
BMDL10 = 0.03 mg/kg/day, based on
cholinesterase inhibition in the brain
of postnatal day 11 (PND 11) male
pups.
Short, Intermediate and
Long-Term Dermal


(Occupational)
BMDL10 = 0.01 mg/kg/day
        UF=100
Dermal absorption rate (rat
   dermal study) = 6%
                   MOE > 100 does not
                  exceed level of concern
Special ChE Study (USEPA 2005)

BMDL10 = 0.01 mg/kg/day, based on
RBC cholinesterase inhibition in adult
rat
Short, Intermediate and
Long-Term Inhalation
(Occupational)
BMDL10= 0.01 mg/kg/day
        UF=100
Inhalation absorption rate =
         100%
                   MOE > 100 does not
                  exceed level of concern
Special ChE Study (USEPA 2005)

BMDL10 = 0.01 mg/kg/day, based on
RBC cholinesterase inhibition in adult
rat
Cancer (oral, dermal,
inhalation)
"Not likely"
                                            Risk assessment not required

-------
             2.      Dietary Exposure and Risk from Food and Water

       A refined (Tier 3) acute probabilistic dietary risk assessment was conducted
using DEEM-FCID™, Version 2.02, which incorporates consumption data from
USDA's CSFII, 1994-1996 and 1998,  as well  as monitoring data from PDF and the FDA
Surveillance Monitoring Program, estimated percent crop treated information, and
processing/cooking factors, where applicable.  EPA has determined that, because of the
rapid reversibility of cholinesterase inhibition  related to carbofuran, the acute dietary
assessment would be protective of any chronic exposures in the diet.  Therefore, a
separate chronic dietary exposure assessment was not conducted. Exposure estimates
are reported in milligrams per kilogram of body weight per day, and risk is expressed as
a percent of the aPAD. Exposure estimates that are less than 100% of the PAD  are
below the EPA's level of concern.

       Combined anticipated residues of carbofuran and 3-hydroxycarbofuran on food
were included in the acute assessment.  Acute  anticipated residues for many foods
(artichoke, cucumber, melons, milk, peppers, potatoes, pumpkin, squash, strawberry and
sweet corn) were derived using USDA Pesticide Data Program (PDF) monitoring data
from recent years (through 2003  for all commodities except milk, for  which recently
available 2004 data were used).  For artichokes, PDF data for peppers were used as
surrogate data. Anticipated residues for bananas and grapes were derived using
monitoring data from the 2000 Carbamate Market Basket Survey.  Most of the samples
analyzed by the PDF and the Carbamate Market Basket Survey Task Force contained no
detectable residues of carbofuran or its 3-hydroxy metabolite.

       A value equal to /^ the combined limits of detection (LODs) of carbofuran and 3-
hydroxycarbofuran was assumed for samples with non-detectable residues, with zeros
incorporated to account for the percent of the crop not treated with carbofuran.  For
commodities with no monitoring data available (cranberries, coffee, sugar beets,
sugarcane and sunflowers) and for field crops  that are typically blended prior to
marketing (barley, field corn, oats, rice, soybean, and wheat), anticipated residues were
based on field trial data.  Although PDF data are generally assumed to provide more
refined estimates of exposure than field trial data, they  may sometimes overestimate
exposure, particularly for blended commodities, such as those listed above, with low
percent crop treated estimates, no detections in the PDF data and relatively high /^ LOD
values.  Therefore, field trial data were used, with adjustments  for percent crop treated,
to provide more refined exposure estimates for these commodities. Exposure estimates
are reported in milligrams per kilogram of body weight per day, and risk is expressed as
a percent of the aPAD. Exposure estimates that are less than 100% of the aPAD are
below the EPA's level of concern.

       The estimated acute dietary (food  only) exposure exceeds the  Agency's level of
concern for the U.S.  population and all reported population subgroups at the 99.9th
percentile of exposure. Carbofuran  dietary exposure at the 99.9th percentile was
estimated at 0.000154 mg/kg/day for the U.S.  population (260% of the aPAD)  and

-------
 0.000292 mg/kg/day (490% of the aPAD) for children 1-2 years old, the population
 subgroup with the highest estimated dietary exposure. See Table 3 below.

Table 3.  Summary of Acute Dietary Exposure and Risk for Carbofuran for Food Alone
(aPAD = 0.00006 mg/kg/day) at 99.9th Percentile of Exposure
Population Subgroup
General US Population
Infants < 1 year
Children 1-2 years old
Children 3-5 years old
Dietary Exposure (mg/kg/day)
0.000154
0.000182
0.000292
0.000290
%aPAD
260
300
490
480
 Surface Water Estimated Drinking Water Concentrations

       For surface water, estimated environmental drinking water concentrations
 (EDWCs) were calculated using the PRZM/EXAMS model. If appropriate, regional
 percent cropped area factors (PCA) were considered. EDWCs represent the range of
 concentrations that are expected to result from the annual use of carbofuran over a 30-
 year period at lowest and maximum application rates in different growing areas
 nationally, and vary over several orders of magnitude across use areas.  Only acute
 values are presented here since the Agency did not assess chronic or cancer dietary risks
 for carbofuran. For an in-depth discussion of modeling and the range of values, please
 see the carbofuran drinking water assessment.

Table 4. Acute EDWCs (ppb) for Carbofuran on Selected Agricultural Crops.
 (Ranges of acute concentrations based on a distribution of default PC As.)
Location/Crop
Potato
CA Grape
Alfalfa
Alfalfa
ID Potato
Tobacco
Cotton
Corn
Sorghum
Using Lowest Label Rate1
0.25-3.1
0.4
0.13-1.5
0.11-1.2
—
8-17
14-18
19-36
2.4-7.8
Using Highest Label Rate1
1.6-20
4.3
1.1-12
0.86-10
10
12-26
57-72
26-49
23-75
1. One-in-ten-year annual peak concentration

        3-Hydroxycarbofuran has not been shown to form in the majority of
 environmental fate studies, with the exception of one study in which it was detected in
 low amounts as a result of soil photolysis.  Therefore, 3-hydroxycarbofuran was not
 included in the Agency's human drinking water exposure assessment. While estimation
 of potential exposure to 3-hydroxycarbofuran remains an uncertainty in the human
 drinking water assessment, it is not expected to significantly add to exposure estimates
 (maximum concentrations in monitoring were approximately 6% of carbofuran
 concentrations).
                                       10

-------
Groundwater Estimated Drinking Water Concentrations

       Estimation of carbofuran in groundwater was based on a study conducted by the
registrant. Following detection of carbofuran in ground water in Long Island, NY, FMC
voluntarily conducted a prospective groundwater (PGW) monitoring study during 1981-
1983 near Salisbury, Maryland to assess impacts from the labeled use of carbofuran.
Soils at the study site are sandy and promote leaching to groundwater. A corn plot had
one application of Furadan 10G (totaling 3.0 Ibs a.i./A; the labeled rate has since been
reduced to 1  Ibs a.i./A on corn for these soils).

        Because this prospective ground water study was conducted over only one
growing season, the reported ground water concentrations do not represent impacts from
carbofuran use in multiple years.  Thus, EPA used superpositioning techniques to provide
estimates of concentrations following long-term (25 years) use of carbofuran at current
label rates. These estimation techniques assumed chemical transformation processes and
transport and interaction mechanisms are linear with respect to concentration. Based on
these assumptions, the carbofuran concentrations in groundwater for various application
rates were estimated (Table 5). EDWCs for ground water, estimated from PGW
monitoring data, range from 1.4 ppb (low application to alfalfa) to 110 ppb (high
application to grapes).

Table 5.  Estimated 90-day Average Concentrations of Carbofuran in Shallow
Groundwater for a Range of Application Rates
Crop
Alfalfa
Cotton
Corn
Corn
Tobacco
Grapes
Application Rate (Ibs a.i./A)
0.125
0.25
1.0
2.0
4.0
10.0
Groundwater EDWCs (ppb)
1.4
2.8
11
22
44
110
Water Monitoring Data

        Available groundwater monitoring studies conducted in the 1980s at locations
associated with carbofuran uses report peak carbofuran concentrations ranging from 1.4-
176 ppb. Several studies reported peak concentrations in the 50 ppb range resulting from
application rates comparable to currently used application rates. Non-targeted
monitoring tends to show detections at lower concentrations, rarely exceeding 1 ppb,
although higher concentrations have been reported. Over the last decade, non-targeted
ground water monitoring reports indicate fewer locations with detections.  Consistent
with its  environmental fate properties, carbofuran has been detected more frequently and
at higher concentrations  in acidic environments.  The most vulnerable drinking water
sites appear to be shallow private wells near carbofuran use areas, where the ground
water has a lower pH.
                                        11

-------
        Only non-targeted monitoring data are available for surface water; consequently,
detections cannot be directly associated with specific use sites or locations that are most
vulnerable to contamination. Few detections exceeding 1 ppb have been found since the
mid-1990s.

       Detectable residues of carbofuran (no 3-hydroxycarbofuran found) were found in
14 out of 1418 PDF water samples (data from 2001-2003).  Carbofuran residues ranged
from 0.001 ppb to 0.079 ppb. These data were not deemed appropriate for use in risk
assessment as the data may not be reflective of areas with significant carbofuran use and
the community water systems sampled by PDF are generally deep ground water or
surface water systems and do not include private wells. Since the highest carbofuran
concentrations are likely to occur in shallow, private wells in areas where carbofuran is
used, use of the PDF data would not be protective of people whose drinking water comes
from such wells.

       The Agency evaluated data from state, USGS and registrant monitoring programs.
The EPA Office of Water collected monitoring data for compliance with the Safe
Drinking Water Act and in a 2002 report described levels of carbofuran found in 16 states
in finished drinking water.  No system exceeded the carbofuran MCL of 40 ppb;
however, several systems exceeded concentrations of 7 and 4 ppb.  Because these data
were collected for compliance purposes (i.e., not to determine acute exposures) they are
not included directly into the risk calculations.  Some forms of drinking water treatment
such as softening may reduce concentrations of carbofuran in finished water, but other
water treatment methods do not affect concentrations.

              3.      Residential and Other Non-occupational Risk

       Carbofuran is a restricted use pesticide and is not registered for residential or
other non-occupational uses. Therefore, no residential exposure and risk assessment was
conducted for carbofuran.

              4.      Aggregate Exposure and Risk

       The Food Quality Protection Act (FQPA) amendments to the Federal Food, Drug
and Cosmetic Act (FFDCA, Section 408(b)(2)(A) (iii)  require "that there is a reasonable
certainty that no harm will result from aggregate exposure to the pesticide chemical
residue, including all  anticipated dietary exposures for which there is reliable
information."  Aggregate exposure will typically include dietary exposures (food plus
drinking water), residential uses of a pesticide, and other non-occupational sources of
exposure.

       There are no residential uses of carbofuran. Therefore, when evaluating
aggregate exposures,  only the dietary pathways of food and  drinking water would be
relevant.
                                        12

-------
       Acute dietary exposure and risk from food alone exceeds the Agency's level of
concern (i.e., >100% aPAD). For the most highly exposed subpopulation (children 1-2
years old), the acute dietary (food only) risk estimate is 490% of the aPAD. For the
general U.S. population, the acute dietary (food only) risk estimate is 260% of the aPAD.

       Using the PRZM/EXAMS model, the acute EDWCs in surface water range from
0.11 ppb (low application rate to alfalfa) to 75 ppb (maximum label application rate to
sorghum) for nine crop location scenarios. EDWCs for ground water, based on
prospective ground water monitoring data, range from 1.4 ppb (low application to alfalfa)
to 110  ppb (maximum application to grapes).

       If one assumes that there are no acute dietary food exposures to carbofuran and all
of the allowable exposure occurred through water sources (i.e., assuming the aPAD of
0.00006 mg/kg/day is completely allocated to exposure to residues in water), the drinking
water level of concern (DWLOC) would be 2.1 ppb for the general U.S. population and
0.6 ppb for infants and children.  These values are based on daily water consumption
estimates of two liters for adults  and one liter for infants and children. DWLOCs based
on consumption of a single 8 ounce serving of water would be 2.6 ppb for infants and
children and 18 ppb for adults.  Therefore, even if all of the allowable dietary exposure
(i.e., the entire aPAD or "risk cup") occurred through a single serving of drinking water,
the Agency would have concerns for acute exposure to carbofuran, particularly for
individuals (both adults and children) who may derive their water from vulnerable
watersheds that are highly cropped and where carbofuran applications may be made up to
the maximum label rates.  Exposure to individuals (adults) whose drinking water comes
from sources where crop/location scenarios result in lower EDWCs (scenarios with lower
applications) may not be of concern if the entire risk cup were available for water
exposures.

             5.     Occupational Exposure and Risk

       Workers can be exposed to a pesticide through mixing, loading, and/or applying a
pesticide, or re-entering treated sites. Occupational risk is measured by a Margin of
Exposure (MOE), which describes how close the occupational exposure comes to a point
of departure (e.g., BMD or NOAEL). The target MOE for carbofuran is 100, meaning
that MOEs that fall below 100 indicate a possible need for mitigation.

       Occupational  handler scenarios were  assessed using the short-term endpoint for
dermal and inhalation exposures. The short-term dermal and inhalation endpoint is a
BMDLio of 0.01 mg/kg/day, based on red blood cell ChE inhibition in adult male rats.
Additionally, a dermal absorption factor of 6% has been used, based on a 24-hour
exposure duration from a  dermal penetration study. The UF for both dermal and
inhalation endpoints is 100 (10X for intraspecies variability and 10X for interspecies
extrapolation). Dermal and inhalation exposures were combined to assess handler risk.

       Occupational  handler risk estimates have been assessed for short-term exposures.
Intermediate-term and long-term exposures were not assessed, as ChE inhibition does not
                                        13

-------
increase with continued exposure to carbofuran and because of the rapid reversibility of
ChE inhibition.
       No chemical-specific data for assessing human exposures during pesticide
handling activities were submitted, so short-term dermal and inhalation exposures for
handlers were developed using the Pesticide Handlers Exposure Database (PHED)
Version 1.1.

       The Agency has determined that there are potential exposures to individuals who
mix, load, apply, and otherwise handle carbofuran during the usual use patterns
associated with the pesticide.  Thirteen major occupational exposure scenarios were
identified based on the type of equipment that potentially can be used to make carbofuran
applications.  These scenarios are listed in Table 6 below.

       The calculations of short-term total risks indicate that most occupational handler
risks are above  the Agency's level of concern (i.e., MOEs less than 100), even at the
maximum mitigation level (engineering controls) for all handler scenarios except
mixing/loading granulars for tractor-drawn spreader application (cucurbits, spinach) and
flagging for spray application (corn,  sugarcane).  Additionally, total MOEs for
mixing/loading/applying liquids for application to any crop via backpack sprayer were
greater than 100 with baseline protection. Total MOEs for mixing/loading/applying
liquids for low-pressure handwand application were greater than 100 with PPE2
protection (single layer protection, gloves, and PF5 respirator).  Table 6 below shows
MOEs for the remaining handler scenarios, which do not reach 100, even with
engineering controls.

Table 6.  Summary of Handler Scenarios Total (Dermal and Inhalation) MOEs with
Engineering Controls (i.e., Maximum MOEs)
Exposure Scenario
Crop
Application
Rate (Ibs
a.i./A)
Daily Area
Treated
(Acres/day)
Total
MOE
MIXER/LOADER
Mixing/Loading
Liquids for Aerial
application
Mixing/Loading
Liquids for
Chemigation
application
Mixing/Loading
Liquids for
Groundboom
application
Alfalfa, Corn (field and pop),
Cotton
Potatoes
Sorghum
Small grains (wheat, barley,
oat), Soybeans
Ag Fallow/Idle land
Corn (sweet), Sunflowers
Sugarcane
Grapes
Grapes
Ornamentals
Coffee (seedbeds)
Tobacco
lib
21b
0.50
0.25
0.19
0.50
0.75
6
10
10
6.90
6
1200
350
1200
1200
350
350
350
350
80
40
80
80
0.96
1.7
2.0
3.9
18
6.8
4.4
0.56
1.5
2.9
2.1
2.4
                                        14

-------
Exposure Scenario

Crop
Peppers
Sugar Beets
Sunflowers
Alfalfa, Corn (field and pop),
Cotton
Potatoes
Sugarcane
Sorghum
Corn (sweet)
Artichoke
Small grains (wheat, barley,
oat), Soybeans
Application
Rate (Ibs
a.i./A)
o
3
2
1.40
1
o
3
0.75
0.50
1
1
0.25
Daily Area
Treated
(Acres/day)
80
200
80
200
80
80
200
80
80
200
Total
MOE
4.8
3.0
10
6.0
4.8
20
12
15
15
23
APPLICATOR
Aerial application
Groundboom
application
Applying Granulars for
Tractor-drawn
Spreaders application
Alfalfa, Corn (field and pop),
Cotton
Potatoes
Sorghum
Small grains (wheat, barley,
oat), Soybeans
Corn (sweet), Sunflowers
Ag Fallow/Idle land
Sugarcane
Grapes
Ornamentals
Coffee (seed beds)
Tobacco
Peppers
Sugar Beets
Sunflowers
Alfalfa, Corn (field and pop),
Cotton
Potatoes
Sugarcane
Sorghum
Corn (sweet)
Small grains (wheat, barley,
oat), Soybeans
Artichoke
Cucurbits, spinach
1
2
0.50
0.25
0.50
0.19
0.75
10
10
6.90
6
3
2
1.40
1
3
0.75
0.50
1
0.25
1
0.50
1200
350
1200
1200
350
350
350
80
40
80
80
80
200
80
200
80
80
200
80
200
80
80
1.6
2.7
3.2
6.4
11
29
7.2
2.6
5.2
3.2
4.4
8.4
5.2
18
10
8.4
34
20
26
40
26
52
FLAGGER
Flagging for Spray
application
Potatoes
Sorghum
Small grains (wheat, barley,
oat), Soybeans
2
2
2
350
1200
1200
48
14
14
15

-------
       The Agency did not assess risks to workers mixing, loading or applying flowable
carbofuran to pine seedlings as a slurry dip because there are no appropriate exposure
data to evaluate the risks at this time. In the absence of appropriate data, the exposure for
dipping pine seedlings is considered to be less than or similar to exposures from
handwand applications to ornamentals with regards to amount of product which could be
handled. Total MOEs for mixing/loading/applying liquids for low-pressure handwand
application were greater than 100 with single layer clothing, gloves, and a PF5 respirator.
As a conservative measure, this level of protective clothing will be required for flowable
carbofuran use on pine seedlings.

Postapplication Occupational Risk

       For workers entering a treated site, restricted entry intervals (REIs) are calculated
to determine the minimum length of time required before workers can safely reenter (i.e.,
MOEs > 100). Many of the registered uses of carbofuran involve applications to the soil
only and do not result in treatment of plant foliage.  Therefore, these scenarios were not
included in the postapplication risk assessment.  However, multiple applications of sprays
to foliage may occur for a number of crops.  EPA expects  harvesting for all these
particular crops to be fully mechanized.

       For those crops for which postapplication exposures are expected to occur,
exposure was estimated using dislodgeable foliar residue (DFR) data for carbofuran
applied to corn, cotton, and potatoes. MOEs failed to reach 100 within the currently
prescribed REIs for most of these crops.

       Short-term exposures may occur for several crops requiring reentry by crop
advisors. Such exposures also may occur for field workers involved in irrigation
activities, early season hoeing and thinning, and de-tasseling corn grown for seed.

       A 14-day restricted entry  interval is specified on current carbofuran labeling for
foliar application to corn, sunflowers, and sorghum.  A 48-hour REI is specified on
product labels for all other crops, based on the acute toxicity of carbofuran (per EPA's
Worker Protection Standard).

       Most crops with postapplication activities failed to reach MOEs of 100 within the
currently prescribed REIs. Only  sunflower and sorghum had postapplication MOEs of
100 within the label REI of 14 days.
                                        16

-------
  Table 7. Crop Groupings, Selected Transfer Coefficients, Treated Crops, Rates,
  Proposed REIs, Current REIs
Transfer
Coefficient
Group
Field/row
crops,
Low/medium
Field/row
crops,
Tall
Sugarcane
Vegetable, root
Crop
Soybeans
Small Grains
Alfalfa
Sugar Beets
Corn
(field and
pop)
Corn
(sweet)
Sunflowers
Sorghum
Sugarcane
Potatoes
Max
Foliar
Rate
(Ib
ai/acre)
0.25
0.25
1
2
1
0.5
0.5
0.5
0.75
1
DFR
Data Used
Cotton
Cotton
Potatoes
Potatoes
Corn (MN site)
Corn (CA site)
Corn (MN site)
Corn (CA site)
Potatoes
Potatoes
Potatoes
Potatoes
Transfer Coefficient
(cm2/hr)
Low
100
100
100
100
100
100
100
100
100
100
100
300
Med
1500
1500
1500
1500
1000
1000
1000
1000
1000
1000
1000
1500
High






17000
17000


2000

# of days until MOE
reaches 100
Low
6
6
4
8
7
25
2
18
0
0
2
4
Med
12
12
>14*
>14*
10
>32*
10
32
13
13
>14*
>14*
High






>11*
>32*




Studies ended at the number of days indicated, and MOEs still had not reached 100.

        Drench applications made to container grown nursery stock may result in dermal
  exposure to workers performing postapplication reentry tasks and for workers handling
  treated soil while moving containers.  However, the Agency has no exposure data to
  estimate these exposures.
               6.
Smoker Assessment
         A short-term inhalation risk assessment for adult smokers has been completed,
  since carbofuran is registered for use on tobacco.  Based on the short-term inhalation
  BMDL10 of 0.01 mg/kg/day (based on red blood cell ChE inhibition in adult male rats),
  the short-term MOE for carbofuran exposure from the use of tobacco is 12.  This
  conservative risk estimate is above HED's level of concern for inhalation exposure to
  carbofuran.
               7.
Human Incident Data
        For a review of the pesticide poisoning incident data for carbofuran, EPA
  consulted the following data bases: (1) OPP Incident Data System (IDS); (2) Poison
  Control Centers (PCC); (3) California Department of Pesticide Regulation; (4) National
  Pesticide Telecommunications Network (NPTN), and (5) National Institute of
  Occupational Safety and Health's Sentinel Even Notification System for Occupational
  Risks (NIOSH SENSOR).  In all, more than 700 possible carbofuran poisoning incidents
  were reported.

        In the IDS, from 1996 through 2003, there have been 42 reported incidents from
  carbofuran exposure.  Common among these reports is evidence that carbofuran is a
                                         17

-------
prevalent cause of eye problems, which was reported in about one quarter of all the cases.
Although data were often limited, most cases involved failure to wear proper protective
equipment, or they occurred when workers were cleaning or repairing spray equipment.

       PCC results for the years 1993 through 2001 for occupational and non-
occupational incidents involving adults and older children and for children under age six
were compared between carbofuran and all other reported pesticides.  The PCC data
indicate that carbofuran exposure is likely to result in more serious medical outcomes and
serious medical care than exposure to other pesticides. Most of the reported symptoms
for carbofuran incidents were specific to cholinergic poisoning and most resulted from
dermal and inhalation exposure, rather than oral exposure. While approximately four
percent of the non-occupational incidents could be attributed to misuse,  or misreading of
the label, it was not possible to determine what percentage of occupational incidents were
attributable to misuse.

       On the list of the top 200 chemicals for which NPTN received calls from 1984 to
1991 inclusively, carbofuran was ranked 37th, with 103 incidents in humans reported.

       In the NIOSH/SENSOR data (surveillance in seven states) there  were 19 reports
due to carbofuran alone,  out of 4,221 reports.

       A 1997 EPA incident review stated that, overall, carbofuran was judged second
among 28 pesticides on measures of hazard derived from  California and PCC data. Most
of the risk from this pesticide is due to use by pesticide handlers, especially mixer/loaders
who handle the concentrated material.  Less often, groups of people have been poisoned
from spray drift of from exposure to field residue.  A 1998 case in California illustrates
the effects from field residues when workers reentered treated cotton fields within two
hours, instead of the required 48 hours, after application.  Such residues  are capable of
causing moderate to relatively serious effects which require medical treatment.

       Detailed descriptions of incidents reported to the California Pesticide Illness
Surveillance Program from 1982 through 2002 identified  a total of 88 cases in which
carbofuran was either used alone or in combination with other chemicals, but was judged
to be responsible for the  reported health effects. The majority of illnesses were of a
systemic type. The majority of incidents occur among handlers who mix, load, and apply
carbofuran in agricultural fields.

       The number and rate of poisoning cases due to carbofuran exposure is sufficient
to warrant priority attention to risk reduction measures for this pesticide.

       B.     Environmental Risk Assessment

       The ecological risk assessment for carbofuran primarily focused  on the liquid
(flowable) formulation because it makes up the greatest portion (> 99%) of carbofuran's
uses. However, since some granular product uses remain, a summary of the associated
                                        18

-------
ecological risk of these uses is presented separately in the ecological risk assessment (see
section 4.0 of Appendix 1 of the ecological risk assessment).

       Terrestrial and aquatic plants were not a part of this risk assessment. Since the
mode of action of carbofuran is cholinesterase inhibition and both terrestrial and aquatic
plant studies show no phytotoxic effects, the Agency does not have concerns for plants as
a result of use of carbofuran.

       Three lines of evidence were examined to evaluate the risk of the use of flowable
carbofuran products to non-target animal species. They include a screening level risk
assessment (deterministic),  a refined assessment (probabilistic) for aquatic risks and acute
risks to birds, and the consideration of field  data for carbofuran.

       First, standard screening level quotient models were used for estimating the acute
and chronic risk to non-target aquatic and terrestrial organisms associated with the major
uses of flowable carbofuran. This screening level ecological risk assessment compared
toxicity endpoints from ecological toxicity studies to estimated environmental
concentrations (EECs) based on environmental fate characteristics and pesticide use data.
To evaluate the potential risk to non-target organisms from the use of carbofuran
products, the Agency calculated risk quotients (RQ), which are the ratio of the EEC to the
most sensitive toxicity endpoint values, such as the median lethal dose (LD50) for
terrestrial organisms or the median lethal concentration (LCso) for aquatic organisms.
These RQ values are then compared to the Agency's levels of concern (LOCs), given in
Table 8, which indicate whether a pesticide, when used as directed, has the potential to
cause adverse effects on non-target organisms. When the RQ exceeds the LOG for a
particular category, (e.g., endangered species), the Agency presumes a risk of concern to
that category. These risks of concern may be addressed by further refinements of the risk
assessment or mitigation. Use, toxicity, fate, and exposure are considered when
characterizing the risk, as well as the relative degree of uncertainty in the assessment.

Table 8. EPA's Levels of Concern and Associated Risk Presumptions
Risk Presumption
Acute Risk - there is potential for acute risk
Acute Endangered Species - endangered species may be
adversely affected
Chronic Risk - there is potential for chronic risk
LOC
terrestrial
animals
0.5
0.1
1
LOC
aquatic animals
0.5
0.05
1
       Secondly, to help understand the ecological risk estimates derived from the
screening level (deterministic) assessment, probabilistic methods were employed to
provide more refined risk estimates that move away from the protective assumptions of
the quotient model by using less conservative exposure scenarios and biological
information on wildlife species likely to be associated with carbofuran use.  The refined
probabilistic assessment models estimate the magnitude and probability of acute effects
                                        19

-------
to non-target species occurring from pesticides by integrating distributions of carbofuran
exposure with distributions of toxicity. The refined risk assessment addresses bird
mortality (acute), as well as survival and reproductive (chronic) effects to fish and aquatic
invertebrates following application of carbofuran. The probabilistic models and methods
were subjected to external  peer review by the FIFRA Science Advisory Panel.

       Lastly, available field data, including field studies, monitoring programs, and
well-documented wildlife kill incident reports attributed to the normal agricultural use of
flowable carbofuran were examined.

       All three lines of evidence support the conclusion that there are risk concerns to
both aquatic and terrestrial species from acute and chronic exposure following the use of
flowable carbofuran: risk concerns are particularly high for avian species.

       For a more detailed explanation of the ecological risks posed by the use of
carbofuran, refer to "Revised Ecological Carbofuran RED Chapter," dated March 8,
2006.

             1.    Environmental Fate and Transport

       Carbofuran is highly mobile in soils and can therefore leach into groundwater and
enter surface water as runoff.  Carbofuran breaks down into several degradates though
hydrolysis, photodegradation and moderate bacterial degradation at rates that depend on
environmental conditions.  Hydrolysis is faster in water with a pH > 7 (basic conditions),
with a half-life ranging from a few hours to 28 days.  Carbofuran is stable to hydrolysis in
acidic water. Photodegradation is fast in a thin water layer, with a half-life of 6 days.  In
the top few millimeters of a sandy loam soil, carbofuran degrades in 78 days.
There is low potential for bioconcentration of carbofuran and its metabolites/degradates.

             2.    Ecological Risk Estimation

                    a.     Terrestrial Organisms

       In its screening level (deterministic) assessment, the Agency assessed exposure to
terrestrial organisms by first predicting the amount of carbofuran residues found on
animal food items and then using information on typical food consumption by various
species of birds and mammals to determine the amount of pesticide consumed. The
amount of residues on animal feed items is based on the Fletcher nomogram and the
current maximum and minimum application rates, maximum numbers of applications,
and potential for residue dissipation between applications.  The Fletcher nomogram is a
model developed by Hoerger and Kenaga (1972) and modified by Fletcher (1994).

                           i)     Birds

       Carbofuran is characterized as "very highly toxic" to birds on an acute oral basis
and "highly toxic" on a sub-acute basis. Chronic toxicity testing in birds showed dose-
                                        20

-------
related parental mortality at all test concentrations, so a NOAEL and LOAEL could not
be established. A LOAEL of <2.0 mg/kg-diet was chosen as the toxicological risk
assessment for chronic risk assessment, since 2.0 mg/kg-diet was the lowest dose tested.

Table 9.  Summary of Avian Toxicity Data Used for Risk Assessment
Test Type
Avian acute effects (oral)

Avian chronic effects
(reproduction)

Species
(Citation)
Fulvous whistling duck
(Dendrocygna bicolor)
(Hudson et al., 1984)

Mallard duck (Anal
platyrhynchos)
(Roberts e/a/./1982b)

Endpoint
LD50 =
0.238 mg/kg
NOAEC:
not
determined
LOAEC = 2
ppm
Toxicity
Category
Very highly
toxic

NA

Affected
Endpoints
NA
Dose-related
parental
mortality at all
test
concentrations
       Acute RQs exceed the LOG for all uses of flowable and granular carbofuran.
Table 10 presents the RQs for flowable carbofuran as they relate to the minimum and
maximum use rates on various crops. The lower end of the range represents RQ values
associated with large birds whose body weight is equivalent to 1,000 g, while the higher
end of the RQ range is associated with small birds of 20 g. For RQs calculated for use of
granular carbofuran, see the Granular Carbofuran Risk Assessment.

Table 10.  Avian (Herbivore) Acute RQs for Flowable Carbofuran Based on Filvous
Whistling Duck LD50 of 0.238  mg/kg (Level of Concern = 0.5)
Crop
Alfalfa
Corn (all)
Cotton
Grapes
Potatoes
Small grains (wheat, oats, barley)
Sorghum
Soybeans
Sugarcane
Sunflowers
Tobacco
RQ Values at Minimum
Application Rates
Large Birds
17
67
28
201
67
17
20
17
67
17
80
Small Birds
144
575
241
1,724
575
144
5,633
144
575
241
690
RQ Values at Maximum
Application Rates
Large Birds
134
804
63
268
157
63
27
63
188
125
121
Small Birds
1,150
6,898
538
2,299
1,345
538
6,553
538
1,613
1,075
1,035
       The chronic risk LOG is also exceeded for all avian species in all application
scenarios. All scenarios compared four different feeding groups: short grass, tall grass,
broadleaf plants/insects and seeds.  The lower RQ values are associated with granivores
(seedeaters) and the higher values are associated with herbivores (short grass eaters). The
NOAEC was <2.0 mg/kg; the Lowest Observed Adverse Effect Concentration (LOAEC)
was 2.0 mg/kg; and at all other concentrations tested, the test birds died.
                                       21

-------
Table 11.  Avian Chronic RQs for Flowable Carbofuran Based on a Mallard NOAEC of
<2.0 mg/kg (Level of Concern = 1.0)
Crop
Alfalfa
Corn (all)
Cotton
Grapes
Potatoes
Small grains (wheat, oats, barley)
Sorghum
Soybeans
Sugarcane
Sunflowers
Tobacco
RQ Values at Minimum
Application Rates
Granivores
(Seed)
1
4
1
15
4
1
1
1
4
1
5
Herbivores
(Short Grass)
15
90
30
135
60
15
30
15
60
50
72
RQ Values at Maximum
Application Rates
Granivores
(Seed)
8
2
2
11
4
4
7
4
11
2
5
Herbivores
(Short Grass)
120
720
56
473
224
56
690
56
168
112
108
       The refined probabilistic assessment (second line of evidence), which assessed
acute avian risk associated with use on corn and alfalfa only, predicted high mortality in
at least some species, regardless of the application rate and method.  The analysis took
into consideration both foliar and soil applications at use rates that span the majority of
application rates for which carbofuran is registered (0.125 to 1.0 Ibs a.i./A).  Based on the
sensitivity distribution, the more sensitive the species, the higher the mortality predicted
from exposure.  It is possible that crops with a higher application rate of carbofuran
would result in greater avian morality. Results of the refined assessment show that from
55 to 95% of the bird species modeled will experience at least some mortality as a result
of the application of flowable carbofuran. At the highest application rate, if exposed,
62% of bird species will experience 10 % mortality on average, and 23% of bird species
will have 70% mortality or greater, with a predicted maximum mortality rate of 93%.
                    ii)
Mammals
       Carbofuran is considered to be highly toxic to mammals on an acute basis.
Chronic toxicity testing on laboratory rats showed reduced offspring survival and body
weight reductions.

Table 12.  Summary of Mammalian Toxicity Data for Terrestrial Animals Exposed to
Dimethoate
Test Type
Mammalian acute effects
(oral)
Mammalian chronic
effects (3 -generation
reproduction)
Species
(Citation)
Laboratory mouse (Mus
musculus)
(Fahmy et al. 1970)
Laboratory rat (Rattus
morvegicus)
(Goldenthal and Rapp/1979,
MRIDs 000305 14,
00030570, and 00079810)
Endpoint
LD50 = 2.0
mg/kg
(males)
NOAEC=
20ppm
LOAEL =
100 ppm
Toxicity
Category
Very highly
toxic
NA
Affected
Endpoints
NA
Decreased pup
survival and
pup body
weight decrease
                                       22

-------
       A refined assessment was not conducted for mammalian species. Few studies
exist on wild mammalian species; therefore, the laboratory mouse LD50 of 2.0 mg/kg/day
was used to calculate RQs. The deterministic assessment showed that the acute and
chronic LOCs are exceeded for herbivorous, insectivorous, and granivorous mammals.
RQs at the lower end of the range are associated with 1,000 g mammals, while the high
end of the range is associated with 15 g mammals.

Table 13. Acute RQs for all Mammal Groups LD50 2.0 mg/kg/day
Crop
Alfalfa
Corn
Potatoes
Sorghum
Cotton
Herbivores and Insectivores
Large Mammal
8
50
15
47
4
Small Mammal
114
684
213
650
53
Granivores
Large Mammal
0.2
1
0.4
1
0.1
Small Mammal
2
9
o
J
9
1
LOC = 0.5

       The chronic mammal LOC is exceeded for most uses. The lower RQ value is
associated with seedeaters (granivores) and the higher RQ is associated with short grass
eaters (herbivores). This is usually the case because short grass contains the highest
pesticide residues.

Table 14.  Mammalian Chronic RQs for Applications LDso 2.0 mg/kg/day
Crop
Alfalfa
Corn
Cotton
Grapes
Potatoes
Sorghum
Herbivores and Insectivores
Large Mammal
0.1
0.2
0.2
1
0.4
0.1
Small Mammal
2
3
3
13
6
2
Granivores
Large Mammal
0.8
5
0.3
5
1
4
Small Mammal
12
72
6
47
22
69
LOC =1.0

                    iii)    Non-target insects

       Carbofuran is characterized as highly toxic to honey bees, based on a honey bee
acute contact study (LD50 = 0.16 jig/bee).

Terrestrial Field Data and Incidents

       The field studies and incident data available for flowable carbofuran (third line of
evidence) support the conclusions of the deterministic and probabilistic risk assessments;
that is, acute risk from the use of flowable carbofuran to non-target terrestrial species is
high.

       The majority of controlled field studies conducted by the registrant support the
deterministic and probabilistic models. These studies demonstrated that bird mortality
occurs at typical to low-end application rates. Of the five studies submitted to the
Agency, four had study designs that were adequate to meet the Agency guideline
                                       23

-------
requirement for detecting significant mortality events. In the acceptably designed
studies, bird mortality in and around treated fields relative to untreated fields was great
enough to reasonably conclude that carbofuran treatment-related mortality was the cause
of death.

       From 1972 to 2000, 31 bird kill incidents have been reported following the use of
flowable carbofuran on five of the major crops where it is registered, and these are almost
exclusively bird kills as a result of direct exposure. A majority (27) of the kills were
reported following carbofuran use on corn and alfalfa, the two major crops where
carbofuran is used. Thirty-seven species with a total  of 7,300 carcasses were reported
found in twelve different states, with both primary and secondary poisonings suspected.

       In the late 1990s, the technical registrant made a number of label changes in order
to reduce drinking water and ecological risks of concern.  These included reducing
application rates and numbers of applications for alfalfa, cotton, corn, potatoes, soybeans,
sugarcane, and sunflowers. EPA therefore  evaluated incidents that have occurred since
1998.  Since 1998, there have been 47 carbofuran incidents reported in EPA's Ecological
Incident Information System (EIIS).  Four of these incidents were from registered uses:

1) 1998 in PA, use on corn (flowable), 2 grackles
2) 1998 in PA, use on corn (flowable), 12 grackles
3) 2000 in NM, use on alfalfa (flowable), 800-1200 snow geese and ducks, and
4) 2000 in CA, use on alfalfa (flowable), 4  bee hives.

The remaining incidents were from intentional misuse (28) or the legality of use  was
undetermined (14).  Of the 47 incidents, 13 were attributed to flowable carbofuran, two
were attributed to granular carbofuran, and for the remaining incidents (32) the
formulation was not reported.

       Additionally, three incidents since 2000 (two  in 2000 and one in 2004) were
reported aggregately by the registrant, and are not in the EIIS. Details are not available
on these incidents.

                     b.     Aquatic Organisms

       For exposure to aquatic fish and invertebrates, EPA considers surface water only,
since most aquatic organisms are not found in groundwater. Surface water models are
used to estimate exposure to freshwater aquatic animals, since monitoring data are
generally not from studies targeted on small water bodies and primary streams within
agroecosystems where the pesticide is used and where many aquatic animals are  found.
The modeling results used in risk calculations for carbofuran are detailed in "Revised
Ecological Carbofuran RED Chapter," dated March 8, 2006.

       Carbofuran concentrations in surface water bodies were estimated using PRZM
and EXAMS and several crop/location scenarios and application rates which were  chosen
to ensure that: (1) the greatest acreage treated with flowable carbofuran was assessed; (2)
                                        24

-------
application rates covered all label use rates; and (3) PRZM/EXAMS scenario site
vulnerability was at the high-end for the crop and carbofuran use combination.  These
crop scenarios are outlined in Table 15 below.

Table 15.  Estimated Environmental Concentrations (ug ai/L)* of Carbofuran in Surface
Water for Selected Use Patterns
Crop/Location
Alfalfa, California
Alfalfa, Pennsylvania
Corn, Illinois
Cotton, Mississippi
Grape, California
Potato, Maine
Potato, Idaho
Sorghum, Texas
Tobacco, North Carolina
Using Minimum Rate
Acute
0.7
0.7
17
10
0.31
3.6
4.5
36
-
21 -day Avg
0.6
0.6
14
7.9
0.24
2.9
3.4
27
~
60-day
Avg
0.4
0.4
9.4
5.5
0.15
2.0
2.2
18
-
Using Maximum Rate
Acute
5.2
5.7
25
11
7.0
26
6.7
36
10
21 -day Avg
4.5
4.6
20
8.2
5.4
21
5.1
27
7.7
60-day Avg
3.0
3.0
17
5.7
3.5
14
3.3
19
5.0
* EEC values represent the l-in-10 year maximum concentration for the designated time interval.
                           i)
Freshwater and Estuarine/Marine Fish
       Carbofuran is very highly toxic to freshwater and estuarine/marine fish on an
acute basis.  Chronic toxicity testing with freshwater fish revealed larval survival as the
most sensitive endpoint (NOAEC = 24.8 ppb a.i., LOAEC = 56.7 ppb a.i.).  The
available chronic test showed estuarine/marine fish were more sensitive than fresh water
fish with embryo hatching as the most sensitive endpoint (NOAEC = 2.6 ppb a.i.,
LOAEC = 6.0 ppb a.i.).  Table  16 summarizes the data that support the toxicity endpoints
used in assessing the risks to fish.

Table 16.  Summary of Measurement Endpoint Values Used to Calculate Screening
Level RQs for Fish
Assessment Endpoint
Freshwater fish acute
effects
Freshwater fish chronic
effects
Estuarine/marine fish
acute effects
Estuarine/marine fish
chronic effects
Test Species
(Citation)
Bluegill sunfish (Lepomis
macrochirus)
(MRID 400980-01)
Rainbow trout
(Oncorhynchus mykiss)
(Ace. GEOCAR08)
Atlantic silverside (Menidia
menidia)
(Ace. 260899)
Sheepshead minnow
(Cyprindodon varigatus)
(MRID 432505-01)
Endpoint
LC50 = 88
NOAEC=
5.7 ppb a.i.
LC50 = 33
NOAEC=
2.6 ppb a.i.
Toxicity
Category
Very highly
toxic
NCa
Very highly
toxic
NCa
Affected Endpoints
NA
Larval survival,
scoliosis
NA
Embryo hatching
aNot characterized

       According to the deterministic assessment, carbofuran is not expected to reach
surface water concentrations high enough to exceed the acute risk LOG for any crop
                                        25

-------
application for freshwater fish.  The chronic risk LOG is exceeded; however, for use on
corn, sorghum, and potatoes. For estuarine/marine fish, there were acute and chronic
LOG exceedences resulting from all uses.

Table 17.  Acute and Chronic RQ Ranges for Fish at Maximum and Minimum
Application Rates
Crop
Alfalfa
Corn
Cotton
Grapes
Potatoes
Sorghum
Tobacco
Freshwater
Acute
0.01-0.06
0.19-0.28
0.11-0.13
0.01-0.08
0.04-0.3
0.41
0.11
Chronic
0.07-0.53
1.6-3.0
0.96-1.0
0.03-0.61
0.35-2.5
3.2-3.3
0.88
Estuarine/Marine
Acute
0.02-0.17
0.52-0.76
0.3-0.33
0.01-2.1
0.11-0.79
1.1
0.3
Chronic
0.15-1.2
3.6-6.5
2.1-2.2
0.06-1.3
0.77-5.4
6.9-7.3
1.9
       Results of the refined probabilistic assessment show that for all uses of carbofuran
modeled for surface water, at least 95% of exposed freshwater fish species will
experience less than 0.5% mortality for any given use.  Reproductive effect levels for the
most sensitive freshwater species, bluegill sunfish, are exceeded in at least 4%
(approximately 1 out of 25 years) of application years for all crops and up to 89% of
application years (approximately 9 out of 10 years) for use on corn.

       For exposed Atlantic silverside fish (estuarine), use on corn and sorghum is
estimated in modeled surface waters to, on average, result in greater than 18% mortality.
However, for the other crop uses modeled, the results indicated no demonstrable
mortality (<1 case of mortality in a million) for the minimum application rate on cotton to
9% mortality for the maximum application to potatoes.
                           ii)
Freshwater and Estuarine/Marine Invertebrates
       Carbofuran is considered to be very highly toxic to freshwater and
estuarine/marine invertebrates on an acute basis.  Table 18 summarizes the data that
support the toxicity endpoints used in assessing the risks to invertebrates.

Table 18.  Summary of Measurement Endpoint Values Used to Calculate Screening
Level RQs for Aquatic Invertebrates
Study Type
Freshwater invertebrate
acute effects
Freshwater invertebrate
chronic effects
Test Species
(Citation)
Water flea (Ceriodaphnia
dubia)
(Bailey etal., 1996)
(Daphnia magna and
Ceriodaphnia dubia)
(Ace. 262093, GEOCAR10)
Endpoint
EC50 = 2.23
ENEC
0.75
Toxicity
Category
Very highly
toxic
Not
classified
Affected
Endpoints
Mortality
Reproduction
                                       26

-------
Study Type
Estuarine/marine
invertebrate acute effects
Estuarine/marine
invertebrate chronic
effects
Test Species
(Citation)
Pink shrimp
(Penaeus duoramm)
(MRID 40228401)
Mysid shrimp
(Americanysis bahia)
(MRID 40536001)
Endpoint
LC50 = 4.6
NOAEC =
0.4
Toxicity
Category
Very highly
toxic
Not
classified
Affected
Endpoints
Mortality
Reproduction
ENEC = Estimated No Effect Concentration

       According to the deterministic assessment, carbofuran is not expected to reach
surface water concentrations high enough to exceed the acute risk LOG or chronic risk
LOG for freshwater invertebrates at minimum label rates for alfalfa and grapes. All other
uses exceed the acute and chronic risk LOCs. For estuarine/marine invertebrates, the
acute LOG was exceeded for saltwater fish for corn, potatoes, and sorghum uses, with the
chronic LOG exceeded for all uses except at minimum application rates to alfalfa and
grapes.

Table 19.  Acute and Chronic RQ Ranges for Invertebrates at Maximum and Minimum
Application Rates
Crop
Alfalfa
Corn
Cotton
Grapes
Potatoes
Sorghum
Tobacco
Freshwater
Acute
0.31-2.6
7.6-11
4.5-4.9
0.14-3.1
1.6-12
16
4.5
Chronic
0.8-6.1
19-27
11
0.32-7.2
3.9-28
36
11
Estuarine/Marine
Acute
0.15-1.2
3.7-5.4
2.2-2.4
0.07-1.5
0.78-5.7
7.8
2.2
Chronic
1.5-12
35-50
20-21
0.6-14
7.2-53
68
19
       In the refined probabilistic assessment, for modeled surface water, on average at
least 5% of exposed freshwater invertebrate species were estimated to experience greater
than 80% mortality and 25% of exposed freshwater species were estimated to have up to
28% mortality for most uses of carbofuran, except for the Idaho and Washington Special
Local Need (SLN) labeled rate on potatoes. Reproductive effect levels for C. dubia, the
most sensitive freshwater invertebrate tested, were exceeded for nearly all uses, except
cotton and the Idaho and Washington SLN labeled rate for potatoes, in all application
years. The frequency of exceedences of the reproductive level was in the range of 70%
for cotton and 43% for the Idaho and Washington SLN labeled rates.

       For exposed pink shrimp, results of the refined assessment show essentially 100%
mortality in modeled surface waters for use on corn and sorghum and greater than 83%
mortality for use on potatoes.  For the other application rates, methods and crops, the
median percent mortality estimate for exposed pink shrimp populations ranges from 0.6%
for the minimum application rate for cotton to 69% for the maximum application rate on
grapes.
                                       27

-------
Aquatic Field Data and Incidents
       In comparison to birds, relatively few incidents with fish and shellfish have been
reported, and only limited monitoring has been conducted in association with the use of
liquid carbofuran in aquatic habitats.  In California, elevated levels of carbofuran in the
Colusa Basin resulted in the listing of that area for Total Maximum Daily Load (TMDL)
development. Eight incidents have been attributed to carbofuran use according to the
label directions.  Two of these incidents were associated with flowable carbofuran
formulations, two with granular, and for the remainder, the formulation was not reported.
More than 600 fish were killed in two ponds following use of liquid carbofuran spray on
alfalfa in Clark County, Missouri, following a rain event in May 1981.  Another incident,
involving liquid carbofuran chemigation to grapes, occurred in San Joaquin County,
California.  In that incident (November 1991), more than 3,000 fish, 4,000 crayfish and
frogs, and 5,000 other large aquatic invertebrates were killed in a creek near a vineyard.

              3.      Risk Characterization

       The Agency has taken action in the past for avian risks from the granular
formulation of carbofuran.  To arrive at the current decision, the Agency used multiple
lines of evidence, including refined probabilistic risk estimates, to conclude that the
flowable formulation of carbofuran also poses significant acute risks to birds. In
addition, based on the previously conducted risk assessments, and extrapolating from the
assessments on the flowable formulation, EPA continues to believe that the granular
formulation poses significant acute risks to birds.

       The terrestrial  risk assessments also show acute and chronic risks to mammals and
chronic risks to birds.  The aquatic assessments show some risks to fish and significant
risks to aquatic invertebrates.  There is lower confidence in the estuarine/marine aquatic
risk conclusions relative to the other non-target organism assessments.

       Carbofuran has often been misused to poison predators, including foxes, coyotes,
wolves, and bears. The technical registrant has conducted an educational/stewardship
program to deter misuse, but intentional baiting continues to be a concern with
carbofuran.

       Many carbofuran incidents which have been classified as "misuse" or "off-label"
appear to be the result of mistakes in application, rather than deliberate misuse. Given
the high toxicity of carbofuran, the margin of error is small so that a minor mistake can
have serious consequences.

       There is high confidence in these risk assessment findings since the deterministic
and probabilistic risk assessments, as well as controlled field studies and incident
reviews, all support the same conclusion: that  carbofuran use poses potentially serious
risks to non-target organisms.
                                        28

-------
              4.     Endangered Species Considerations

       The Agency's preliminary risk assessment for endangered species indicates that
RQs exceed the endangered species LOG for terrestrial and aquatic animals, indicating
the potential for direct effects. Further, potential indirect effects to any species dependent
upon a species that experiences effects from use of carbofuran can not be precluded based
on the screening level ecological risk assessment. These findings are based solely on
EPA's screening level assessment and, because they do not take into account such factors
as whether the species would be expected to be exposed to carbofuran, do not constitute
"may affect" findings under the Endangered Species Act.

       EPA is currently engaging in informal consultations with the Fish and Wildlife
Service and the National Marine Fisheries Service, which is a part of the National
Oceanic and Atmospheric Administration.  This means that the Agencies are working
together to conduct a full endangered species assessment for carbofuran, which is
separate from this IRED.  The likelihood of potential impacts to endangered species will
need to be assessed for all counties in which: 1) crops registered for carbofuran use are
grown; and 2) contain habitat for at least one listed species.
IV.    Interim Risk Management, Reregistration, and Tolerance Reassessment
Decision

       A.     Determination of Reregistration Eligibility

       Section 4(g)(2)(A) of FIFRA calls for the Agency to determine, after submission
of relevant data concerning an active ingredient, whether or not products containing the
active ingredient are eligible for reregi strati on. The Agency has previously identified and
required the submission of the generic (technical or manufacturing-use grade) data
required to support reregi strati on of products containing carbofuran as an active
ingredient.

       The Agency has completed its review of submitted data and its assessment of the
ecological, occupational, and dietary risks associated with the use of pesticide products
containing the active ingredient carbofuran. Based on these data, the Agency has
sufficient information on the human health and ecological effects of carbofuran to make
its interim decisions as part of the tolerance reassessment process under FFDCA, as
amended by FQPA, and the reregi strati on process under FIFRA, pending completion of
the cumulative assessment of the N-methyl carbamate class of pesticides, of which
carbofuran is a member.  Additional mitigation may be necessary after this cumulative
assessment is completed.

       The Agency has determined that all products containing carbofuran are not
eligible for reregi strati on. Some uses  have been identified as providing moderate benefits
to growers, and those will be subject to a phase-out.
                                       29

-------
       B.     Public Comments and Responses

      Through the Agency's public participation process, EPA worked extensively with
stakeholders and the public to reach the regulatory decisions for carbofuran.  During the
most recent public comment period on the risk assessments, which closed on May 22,
2006, the Agency  received many sets of comments from stakeholders. These included
comments from the technical registrant, growers, the Fish and Wildlife Service, the
National Agricultural Aviation Association, the Natural Resource Defense Council, and
others. The comments included some urging the Agency to regulate carbofuran more
stringently, as well as some requesting that the Agency retain certain uses. These
comments, in their entirety, are available in the public docket (docket # OPP-2005-0162)
at http://www.regulations.gov. EPA has prepared responses to these comments and they
are posted in the docket, along with this IRED.  The Agency also received comments
after the comment period closed, including 23 additional grower comments in support of
carbofuran and several thousand comments from private citizens requesting that the
Agency cancel use of carbofuran.

      In addition, EPA worked with USDA to solicit input from the grower community
on the importance of carbofuran use for those crops with < 1% of cropped area treated
with carbofuran. EPA received many comments from growers through this process.
EPA has considered these comments, and will be responding to them through a formal
response to comments memo, which will be placed in the public docket,  along with this
document.

       The IRED and technical supporting documents for carbofuran are also available
to the public through EPA's electronic public docket and comment system, the Federal
Docket Management System (FDMS), under [legacy] docket identification (ID) number
EPA-HQ-OPP-2005-0162. In addition, the carbofuran IRED may be downloaded or
viewed through the Agency's website at
http://www.epa.gov/pesticides/reregistration/status.htm.

       C.    Regulatory Position Under FIFRA and FFDCA

       The following is a summary of the rationale for managing risks associated with
the use of carbofuran.  Under FIFRA, the Agency is proposing to cancel all uses of
carbofuran, due to ecological and occupational risks of concern (See the ecological and
human health risk assessments for carbofuran).  In addition, there are dietary risks of
concern from some crops. See the  first listing of crops under Mitigation Summary below.
Benefits are low to moderate for all of these uses, and do not outweigh the risks.

       There are several uses for which residues do not pose dietary risks of concern and
which have moderate benefits to growers [artichokes, chile peppers in the Southwestern
U.S., cucurbits (granular formulation only), spinach grown for seed, sunflowers, and pine
seedlings in the  Southeastern U.S.]. For these uses, EPA is allowing a 4-year phase-out
in order to allow time for new alternatives to become available to growers. In addition,
import tolerances will be maintained for bananas, coffee, rice,  and sugarcane. Dietary
                                       30

-------
risks from the imported foods are below the level of concern for these crops when
considered together. For bananas, sugarcane, and coffee, however, benefits to U.S.
growers are low when compared to ecological and occupational risks from domestic uses
of these crops.  Carbofuran is no longer registered for use on rice in the U.S. Dietary
risks of phase-out crops plus these imported foods are below the Agency's level of
concern.

              1.      Mitigation Summary

       •       Cancellation based on high ecological and worker risks and low
              economic benefits for growers

              Sorghum            Alfalfa              Sweet corn
              Cotton               Grapes              Field corn and popcorn
              Wheat               Potatoes            Bananas/plantains
              Cucurbits (flowable)  Oats                Soybeans
              Barley               Tobacco            Fallow/idle land
              Sugarcane           Ornamentals         Sugar beets
              Peppers (except chile)

       •       4-year  Phase-out for the crops which have moderate benefits to
              growers.

              Artichokes, chile peppers in the Southwestern U.S.,  cucurbits (granular
              formulation only), sunflowers, spinach grown for seed, and pine seedlings
              in the Southeastern U.S.

              2.      Regulatory Rationale

       The Agency evaluated the relationship of risks and benefits for all carbofuran uses
on a use-by-use basis.  These analyses show high ecological and occupational risks for all
carbofuran uses. In addition, as discussed below, the benefits associated with most crops
are low, although some uses have moderate benefits. Based on the assessment of
ecological and human  health risks associated with carbofuran uses, the Agency has
determined that all uses of carbofuran do not meet the standard for  continued registration
under FIFRA.

       The Agency has identified a few niche uses, however, for which there are
moderate benefits to growers. In the short term, at least, these moderate benefits would
justify retaining uses for a limited time.  The Agency believes that there are not enough
affordable alternatives to provide effective pest control for artichokes, chile peppers
grown in the Southwestern U.S., cucurbits (granular formulation only), spinach grown for
seed, pine seedlings grown in the Southeastern U.S., and sunflowers. EPA believes,
however, that with the development of newer chemistries and other alternative pest
control practices, the benefits of these uses will decrease. Therefore, a phase-out period
of four years, with some additional restrictions to ensure the risks are reduced to

-------
acceptable levels, is appropriate, given the current risk/benefit analyses. Cancellation of
all but the phase-out crops reduces 98% of the total annual carbofuran use.

       Additionally, some uses of carbofuran result in dietary risks above the Agency's
level of concern under FFDCA. Therefore, EPA has determined that, in addition to
significant occupational and ecological risks, these uses would not be eligible for
reregi strati on because the Agency cannot determine that the tolerances for such crops
meet the FQPA safety standard, based on the contribution of these uses to the aggregate
risks for carbofuran. The uses which do not fit within the dietary risk cup based on food
residues alone from the individual commodity are: sweet corn, potatoes, and flowable
carbofuran on the following cucurbits:  pumpkins, squash (summer and winter), casaba
melons, cucumbers, honeydew, and watermelon. Additionally, the dietary contribution
of carbofuran in milk exceeds the Agency's level of concern for infants and children with
corn and alfalfa being cattle feed items which are assumed to be the primary sources of
residues in milk.  The risk estimates for cucurbits are based on both granular and
flowable carbofuran treatments at current usage levels.  Estimated dietary risks based on
the granular use only, with the current production cap of 2,500 pounds  per year, are
below the level of concern.

       The Agency also has dietary risk concerns posed by exposure from drinking water
sources. Since food alone completely fills the risk cup (i.e. exposure is greater than
100% of the aPAD), any level of carbofuran residues in drinking water would result in
additional risks of concern.  Modeling estimates of residues in surface and ground water
from all uses result in residue values above EPA's level of concern.  In addition, recent
USGS NAWQA monitoring data show multiple detections at low concentrations.  The
Agency recognizes that shallow, slightly acidic  groundwater sources are the most
vulnerable to  carbofuran contamination. Such groundwater sources are located primarily
in portions of the Southeast and the east coast of the United States.  The uses for which
EPA is not proposing immediate cancellation are those that are not expected to
significantly contribute to groundwater contamination since they are limited in spatial
extent of production (artichokes, chile peppers), applied in arid regions or in areas where
pH is higher (chile peppers,  sunflowers), or limited due to method of treatment (pine
seedling dip).  Cancellation of all other uses will reduce the amount of carbofuran applied
from approximately 1 million pounds annually to approximately 19,500 pounds of use
remaining for four years.

       Additionally, because dietary risks from use  of flowable carbofuran on cucurbits
alone exceed the risk cup based on PDF food residue monitoring data and a high percent
crop treated, the four year phase-out for cucurbits applies only to granular carbofuran.

       The Agency will maintain import tolerances  for bananas, coffee, rice, and
sugarcane.  Dietary risks from the import tolerances are below the Agency's level of
concern when considered together with the food residues from the phase-out crops (56 %
of the aPAD).  There are currently domestic uses for bananas, sugarcane, and coffee, but
they are ineligible for reregi strati on based on low benefits and ecological and
occupational risks of concern.
                                        32

-------
              3.     Significance of Use

       Carbofuran is a systemic insecticide which is used to control pests on a variety of
fruit, vegetable, and field crops.  Use has been declining in recent years and is now
mostly limited to niche uses. Adequate alternatives exist for all crops except artichokes,
chile peppers in the Southwestern U.S., cucurbits, spinach grown for seed, sunflowers,
and pine seedlings in the Southeastern U.S. Use on cucurbits will be limited to the
granular formulation based on dietary risks.

       During the two public comment periods  on the carbofuran risk assessments, the
Agency received many grower comments in support of retaining carbofuran use for
various crops.

       EPA divided uses into two groups based on percent crop treated. If a low
percentage of a crop is treated, the Agency makes the preliminary assumption that the
significance of use on that crop is also low. For these crops, the Agency consulted with
the USD A Office of Pest Management Policy (OPMP) to determine whether there were
niche uses which should be considered in any mitigation plan. The nineteen use sites in
this category are:  bananas, barley, coffee, cotton, cranberry, flax, grapes, oats,
ornamentals, pine forests, plantains, sorghum, soybeans, spinach grown for seed, sugar
beets, sugarcane, sunflowers, tobacco, and wheat.  OPMP received comments from the
Integrated Pest Management Centers on carbofuran use on these crops. In general, these
comments supported the conclusion that minimal impacts would be expected if
carbofuran were no longer available for those crops with less than one percent crop
treated.

       For those use sites with either greater than 1% crop treated or at least 100,000 Ibs
carbofuran applied each year, the Agency assumed that the higher use frequency implied
significance of use.  For these sites, the Agency  examined carbofuran use patterns,
available alternatives, and the impacts of cancellation to growers. Analyses were
conducted for artichokes, potatoes, field corn, alfalfa, cucurbits, and peppers.  Through
conducting these in-depth benefits analyses, the Agency was able to determine that, with
the exception of artichokes,  certain cucurbits,  and chile peppers, minimal impacts would
also be expected if carbofuran were no longer available for use on those crops with
greater than  1% crop treated or 100,000 Ibs applied annually. The Agency's benefits
assessments will be posted to the carbofuran docket, along with this IRED.

       In addition, after the most recent public comment period closed, the Agency
received some new information from corn growers regarding the use of carbofuran as a
rescue treatment for corn rootworm damage. The Agency therefore took particular care
to examine potential benefits from this use. Corn rootworm pressure has been increasing
for a variety of reasons, including rotation resistance (i.e., rootworms have become
resistant to the control offered by rotating soybeans with corn) and the uncertain
performance of seed treatments under high rootworm pressure.  In addition, increasingly
higher production of corn and continuous corn production are being practiced due to
                                       33

-------
increasing demand for ethanol. When high rootworm pressure is likely, most growers
will use at-plant insecticides, such as tefluthrin, or plant genetically modified Bt corn.
When low to moderate rootworm pressure is likely, growers will typically rely on seed
treatments and survey for root damage instead of rootworm larvae. Clothianidin acts as a
feeding depressant, and thus growers sampling soil in corn fields for larvae may
misinterpret the presence of moribund (inactive) larvae as a control failure.  Extension
entomologists have recommended that growers look for root pruning and damage (rather
than rootworm larvae) to assess the success of seed treatments. In limited circumstances,
some growers may experience yield losses as a result of rootworm damage and have used
carbofuran as a rescue treatment over the corn canopy. However, based on information
from a variety of state extension publications and experts and the general lack of
supporting data, the Agency believes that rescue treatments of carbofuran applied over
the canopy to control corn rootworm damage perform erratically and are not a sound
investment for growers.

        There are  several crops for which the Agency believes there are moderate
benefits to growers: artichokes, chile peppers in the Southwestern U.S., cucurbits,
spinach grown for  seed,  sunflowers, and pine seedlings.  Some moderate benefits have
also been identified for sweet corn for control of the wheat curl mite, which transmits
High Plains  disease. However, the Agency is not planning to allow a phase-out of this
use due to the fact that there are dietary risks  of concern.

Flow able formulation

       Growers apply carbofuran to artichokes for control of cribrate weevils, proba
       bugs, and artichoke aphids.  Effective alternatives exist for aphids; however, the
       alternatives for cribrate weevil and proba bugs are not as effective (see
       Alternatives Assessment for Carbofuran on Artichoke, D. Brassard and S.
       Smearman, July  14,  2006).

•      Carbofuran is used on chile peppers for control of flea beetles, thrips, and
       leafhoppers, as well  as the green peach aphid in Arizona  and Texas. There are
       adequate alternatives available; however, EPA acknowledges that some growers
       would face higher production costs without the availability of carbofuran. In
       addition, use of carbofuran on chile peppers is limited to  Arizona, New Mexico,
       and Texas (see Impact Assessment for Carbofuran on Peppers, N. Zinn and E.
       Rim, June 28, 2006).

•      Carbofuran is used on sunflowers to control stem weevils.  Alternatives are
       available for the  post plant foliar use, but not for the soil  at-plant use.  There are
       also a number of natural enemies available; however, it is unclear whether they
       can achieve adequate control of stem weevils (see Carbofuran Response to
       Comments  and Alternatives Analysis for Crops with Low Usage, D. Brassard et
       al, July 7, 2006).
                                        34

-------
       Only limited alternatives are available for control of pales and pitch weevil in
       pine seedlings (see Carbofuran Response to Comments and Alternatives Analysis
       for Crops with Low Usage, D. Brassard et al, July 7, 2006).

Granular formulation

       The Agency and the technical registrant reached an agreement in 1991 that sales
of granular carbofuran would be limited to 2,500 Ibs a year. This agreement was based
on the ecological risks of concern posed by use of carbofuran, and phase-out use is
limited to cucurbits, spinach for seed,  and pine seedlings only.

       Only limited alternatives are available for control of pales and pitch weevil in
       pine seedlings (see Carbofuran Response to Comments and Alternatives Analysis
       for Crops with Low Usage, D. Brassard et al, July 7, 2006).

       In spinach grown for seed, springtails and European craneflies can cause yield
       losses of 100%, and carbofuran is the only pesticide available for control of these
       pests (see Carbofuran Response to Comments and Alternatives Analysis for Crops
       with Low Usage, D. Brassard et al, July 7, 2006).

       There are adequate alternatives available for cucurbits; however, EPA
       acknowledges that some growers would face higher production costs without the
       availability of carbofuran. [see Impact Assessment for Carbofuran on Cucurbits
       (Cucumbers, Pumpkins, Squash, and Watermelon), N. Zinn and E. Rim, June 14,
       2006.]

       D.     Endangered Species Considerations

       Endangered species acute and chronic LOCs are exceeded for all groups of
terrestrial animals (birds, mammals, and invertebrates) for all uses and for all rates of
flowable and granular formulations of carbofuran, indicating a potential for direct effects
on listed species.  Endangered species acute and chronic LOG are also exceeded for all
groups of aquatic organisms for most uses of flowable and the limited remaining granular
formulations of carbofuran.  Exceedences of the LOCs indicate a potential for effects to
listed species.

       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 (ESA) requires federal agencies to ensure that their actions are
not likely to jeopardize listed species or adversely modify designated critical habitat. To
analyze the potential  of registered pesticide uses that may affect any particular species,
EPA uses basic toxicity and exposure data developed for the REDs/IREDs and considers
these data in relation  to individual species and their locations by evaluating important
ecological parameters, pesticide use information, geographic relationship between
specific pesticide uses and species locations, and biological requirements and behavioral
                                        35

-------
aspects of the particular species, as part of a refined species-specific analysis.
Carbofuran is one of the first chemicals for which the Agency has begun a full, species-
specific endangered species analysis.  The Agency is currently participating in informal
consultations with the Fish and Wildlife Service and the National Marine Fisheries
Service within the National Oceanic and Atmospheric Administration.  The Agencies
hold monthly meetings to exchange information. This species-specific analysis is being
completed separately from this IRED, and will take into consideration any regulatory
changes recommended in this IRED that are being implemented at that time.

       Following this future species-specific analysis, a determination that there is a
likelihood of potential impact to a listed species or its critical habitat may result in:
limitations on the use of carbofuran, other measures to mitigate any potential impact, or
consultations with the Fish and Wildlife Service or the National Marine Fisheries Service
as necessary. If the Agency determines use of carbofuran "may affect" listed species or
their designated critical habitat, EPA will employ the  provisions in the Services
regulations (50 CFR Part 402). Until that species-specific analysis is completed, the risk
mitigation measures being implemented through this IRED will reduce the likelihood that
endangered and threatened species may be exposed to carbofuran at levels of concern.
EPA is not requiring specific carbofuran label language at the present time relative to
threatened and endangered species.  If, in the future, specific measures are necessary for
the protection of listed species, the Agency will implement them through the Endangered
Species Protection Program.

       E.     Food Quality Protection Act Findings and Tolerance Summary

              1.     FQPA

                    a.     Risk Cup Determination

      As part of the FQPA tolerance reassessment process, EPA assessed the risks
associated with this N-methyl carbamate (NMC). The assessment is for this individual
NMC, and does not attempt to fully reassess these tolerances as required under FQPA.
FQPA requires the Agency to evaluate food tolerances on the basis of cumulative risk
from substances sharing a common mechanism of toxicity, such as the toxicity expressed
by the NMCs through a common biochemical interaction with the cholinesterase enzyme.
The preliminary cumulative risk assessment for the NMC Cumulative Assessment Group,
which includes carbofuran, was released in July 2005. The revised cumulative risk
assessment is currently being developed and will be completed  during 2006. The results
of this NMC cumulative assessment, as well as the single chemical carbofuran
assessment, will be considered in the final tolerance reassessment decision for
carbofuran.

      EPA has determined that risk from food (dietary sources  only) exposure to
carbofuran exceeds its own "risk cup" (490% of the aPAD for children). Therefore,
residues in drinking water will be of concern.  Exposure from the crops allowed for four-
year phase-out plus the four crops maintained as import tolerances is estimated at 56% of
                                       36

-------
the aPAD for infants, the population subgroup with the highest exposure. Residues in
water are expected to decline when use ceases.

                    b.    Endocrine Disrupter Effects

       EPA is required under the FFDCA, as amended by FQPA, to develop a screening
program to determine whether certain substances (including all pesticide active and other
ingredients) "may have an effect in humans that is  similar to an effect produced by a
naturally occurring estrogen, or other endocrine effects as the Administrator may
designate." Following recommendations of its Endocrine Disrupter Screening and
Testing Advisory Committee (EDSTAC), EPA determined that there was a scientific
basis for including, as part of the program, the androgen and thyroid hormone systems, in
addition to the estrogen hormone system. EPA also adopted EDSTAC's recommendation
that EPA include evaluations of potential effects in wildlife. For pesticides, EPA will use
FIFRA and, to the extent that effects in wildlife may help determine whether a substance
may have an effect in humans, FFDCA authority to require the wildlife evaluations.  As
the science develops and resources allow, screening of additional hormone systems may
be added to the Endocrine Disrupter Screening Program (EDSP).

              2.     Interim Tolerance Summary

       The Agency is proposing to cancel all uses  of carbofuran based on ecological,
occupational, and dietary risks of concern,  and to revoke all tolerances, with the
exception of bananas, rice, sugarcane, and coffee.  These tolerances will be maintained
for import purposes only. Several uses were identified as having moderate benefits to
growers, and the Agency is proposing to implement a 4-year phase-out for those crops.
Therefore EPA is proposing to delay the effective date of revocation of the tolerances for
artichokes,  corn, peppers, and sunflowers until 2010. All other tolerances will be
proposed for revocation following completion of this IRED.

       A summary of the dietary aggregate assessment for food and drinking water that
supports the finding that the (1) time-limited retention of the uses to be phased out and
(2) retention of the import tolerances  meets the FQPA safety standard is presented in the
Regulatory Rationale section of this document, and in the carbofuran reregi strati on
docket (EPA-HQ-OPP-2005-0162).
                                       37

-------
Table 20. Interim Tolerance Summary for Carbofuran
Commodity
Current Tolerance,
ppm
Tolerance
Reassessment, ppm
Comment/
[Correct Commodity Definition]
Tolerances Listed Under 40 CFR §180.254 (a)
Alfalfa , fresh; alfalfa, hay;
barley, grain; barley, straw;
beet, sugar; beet, sugar,
tops; corn, forage; corn,
fresh (including sweet corn)
(K+CWHR); corn, grain
(including popcorn); corn,
stover; cotton, undelinted
seed; cranberry; grape;
grape, raisin; milk; oat,
grain; oat, straw; potato,
raisins, waste; sorghum,
fodder; sorghum, forage;
sorghum, grain; soybean;
soybean, forage; soybean,
hay; strawberry; wheat,
grain; wheat, straw
Banana
Coffee bean
Cucumber
Melons
Pumpkin
Squash
Pepper
Rice, grain
Sugarcane, cane
Sunflower, seed
10(5)
0.1
0.1
0.4 (0.2)
0.4 (0.2)
0.8 (0.6)
0.8 (0.6)
1 (0.2)
0.2
0.1
1.0 (0.5)
Revoke
0.1
0.1
Revoke
(Maintain at current
level until expiration in
2010.)
Revoke
(Maintain at current
level until expiration in
2010.)
0.2
0.2
Revoke
(Maintain at current
level until expiration in
2010.)

Maintained for import purposes.
[Coffee, green bean] Maintained for
import purposes.
Revoke individual tolerances and
establish a crop group tolerance for
Cucurbit Vegetables Group 9.
Tolerance will expire in 2010.
[pepper, nonbell]
Tolerance will expire in 2010.
No Section 3 registrations.
Maintained for import purposes.
Maintained for import purposes.
Tolerance will expire in 2010.
Tolerances Listed Under 40 CFR §180.254 (c)
Artichoke, globe
0.4 (0.2)
Revoke
(Maintain at current
level until expiration in
2010.)
Tolerance will expire in 2010.
(Number in parentheses reflects the ppm level that residues of carbamates may not exceed.)
                                          38

-------