Reregistration Eligibility
Decision for Dicamba and
Associated Salts

June 8, 2006

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Reregistration Eligibility Decision




               for




  Dicamba and Associated Salts
              List [B]




            Case No. 0065

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 Reregistration Eligibility Decision (RED) Document
          for Dicamba and Associated Salts
Approved by:
             Debra Edwards, Ph. D.
             Director
             Special Review and Reregistration Division
Date:

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Glossary of Terms and Abbreviations
AGDCI
ai
aPAD
AR
BCF
CFR
cPAD
CSF
CSFII
DCI
DEEM
DFR
DWLOC
EC
EEC
EPA
EUP
FDA
FIFRA
FFDCA
FQPA
FOB
G
GENEEC
GLN
HAFT
IR
LCso
LD50
LOC
LOD
LOAEL
MATC
Hg/L
mg/kg/day
mg/L
Agricultural Data Call-In
Active Ingredient
Acute Population Adjusted Dose
Anticipated Residue
Bioconcentration Factor
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
Dislodgeable Foliar Residue
Drinking Water Level of Comparison.
Emulsifiable Concentrate Formulation
Estimated Environmental Concentration
Environmental Protection Agency
End-Use Product
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
Milligrams Per Liter

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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
TGAI
TRR
USDA
USGS
UF
UV
WPS
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
Reregistration 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)
Technical Grade Active Ingredient
Total Radioactive Residue
United States Department of Agriculture
United States Geological Survey
Uncertainty Factor
Ultraviolet
Worker Protection Standard

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                                 Table of Contents

Dicamba Reregistration Eligibility Decision Team	2
I.   Introduction	3
II.    Chemical Overview	3
III.   Summary of Dicamba Risk Assessment	5
  A.  Human Health Risk Assessment	5
    1. Toxicology	6
    2.   Dietary Exposure and Risk from Food and Drinking Water	8
    3.    Residential Exposure and Risk                                          9
    4.   Aggregate Exposure and Risk	11
    5.   Occupational Exposure and Risk	11
    6.   Incidents reports	14
  B. Environmental Risk Assessment	14
    1. Environmental Fate and Transport	14
    2. Environmental Effects	15
    3. Ecological Incidents	19
    4. Risk to Endangered Species                                                 20
IV.   Risk Management, Reregistration, and Tolerance Reassessment Decision	20
  A.  Determination of Reregistration Eligibility	20
  B.   Public Comments and Responses	21
  C.  Regulatory Position	21
    1.   Food Quality Protection Act Findings	21
    2.   Endocrine Disrupter Effects                                              21
    3.   Cumulative Risks	22
    4.   Tolerance Reassessment Summary	22
  D.  Regulatory Rationale	22
    1.   Human Health Risk Assessment	22
    2.   Environmental Risk Mitigation	23
V.  What Registrants Need to Do                                                 24
  A.  Manufacturing Use Products	25
    1.   Additional Generic Data Requirements	25
    2.    Labeling for Manufacturing-Use Products                                25
  B.     End-Use Products	25
    1.    Additional Product-Specific Data Requirements	25
    2.    Labeling for End-Use Products                                          26
VI.   Conclusions	26

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Dicamba Reregistration Eligibility Decision Team


Office of Pesticide Programs:

Environmental Fate and Effects Risk Assessment

Bill Erickson
Ibrahim Abdel- Saheb
Shannon Borges

Health Effects Risk Assessment

Christine Olinger
Tim Dole

Biological and Economic Analysis Assessment

Nicole Zinn
Elisa Rim

Registration Support

Joanne Miller

Risk Management

Kendra Tyler
Laura Parsons

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I.      Introduction

       The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was amended in 1988
to accelerate the reregistration of products with active ingredients registered prior to November
1, 1984. The amended Act calls for the development and submission of data to support the
reregistration of an active ingredient, as well as a review of all data submitted to the
Environmental Protection Agency. Reregistration involves a thorough review of the scientific
database underlying a pesticide's registration.  The purpose of the Agency's review is to reassess
the potential risks arising from the currently registered uses of dicamba, 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. As a result of this
review, the Environmental Protection Agency (hereafter referred to as EPA or the Agency) has
determined that all products containing the active ingredient dicamba are eligible for
reregistration provided that the risk mitigation measures indicated in this document are adopted.
The completion of the dicamba RED does not result in any additional tolerances being reassessed
since all 60 existing tolerances were reassessed in 2000, when a new food use was established
for dicamba [65 FR 33709, (May 24, 2000)].

       Risks summarized in this document are those that result only from the use of dicamba. The
Food Quality Protection Act (FQPA) requires that, when considering whether to establish, modify,
or revoke a tolerance, the Agency consider "available  information" concerning the cumulative
effects of a particular pesticide's residues and "other substances that have a common mechanism
of toxicity." Unlike other pesticides for which EPA has followed a cumulative risk approach
based on a common mechanism of toxicity, EPA has not made a common mechanism of toxicity
finding as to dicamba, and dicamba does not appear to produce a toxic metabolite produced by
other substances. Therefore, for the purposes of reregistration, EPA has not assumed that dicamba
shares  a common mechanism of toxicity with other compounds. For information regarding EPA's
efforts to determine which chemicals have a common  mechanism of toxicity and to evaluate the
cumulative effects of such chemicals, see the policy statements released by EPA's Office of
Pesticide Programs concerning common mechanism determinations and procedures for cumulating
effects from substances found to have a common mechanism of toxicity on EPA's website at
http ://www. epa. gov/pesticides/cumulative/.

II.     Chemical Overview

   •   Common Name: Dicamba is an acid which forms salts in aqueous solutions. Various
       dicamba salts are formulated for herbicidal use and the following compounds are
       considered in this decision document: dimethylamine (DMA) salt, sodium (NA) salt,
       isopropylamine (IPA) salt, diglycolamine (DGA) salt, and potassium (K)  salt.

   •   Chemical Name: 3,6-dichloro-2-methoxybenzoic acid or 2-methoxy-3,6-dichlorobenzoic
       acid

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    •   CAS Registry Numbers:

    Dicamba Acid: 1918-00-9
    Dicamba DMA: 2300-66-5
    Dicamba NA: 1982-69-0
    Dicamba IPA: 555871-02-8
    Dicamba DGA: 1040440-79-1
    Dicamba K: 10007-85-9

    •   OPP Chemical Numbers:

    Dicamba Acid: 029801
    Dicamba DMA: 029802
    Dicamba NA: 029806
    Dicamba IPA: 128944
    Dicamba DGA: 128931
    Dicamba K: 129043

    •   Common Trade Names: Banvel; Trimec

    •   Basic Manufacturer: BASF

Dicamba (2-methoxy-3,6-dichlorobenzoic acid) is a selective benzoic acid herbicide registered
for the post emergent control of certain broadleaf weeds and woody plants.  It was first registered
in the United States in 1967 and is widely used in agricultural, industrial, and residential settings.
According to the EPA Pesticide Sales and Usage Report for 2000/2001, dicamba is the seventh
most commonly used conventional pesticide in the home and garden market sector. The
residential products are typically formulated as dry weed-and-feed products or as liquids in
concentrates or ready-to-use sprays. Many of these formulations include other herbicides to
provide a broader spectrum of weed control.

Use Sites:

    •   Dicamba salts have registered uses on right-of-way areas, asparagus, barley, corn, grasses
       grown in pasture and rangeland, oats, proso millet, rye, sorghum, soybeans, sugarcane,
       and wheat.  Golf courses and residential lawns are also registered.

Mode of Action:

    •   Dicamba is an auxin agonist and causes rapid and uncontrolled growth of the stems,
       petioles, and leaves of sensitive plants. This uncontrolled cell division and growth in turn
       results in the destruction of vascular tissue,  leading to plant death. Weed control is
       generally achieved in 5 to 7 days.

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Formulations:

    •   There are 434 dicamba products formulated as liquids, wettable powders, standard
       granules, and water dispersible granules. Residential products are typically formulated as
       granular weed-and-feed formulations or as liquids in concentrates or ready-to-use sprays.

Methods and Timing of Application:

    •   Application methods include groundboom, rights-of-way sprayer, turfgun, backpack
       sprayer, tractor-drawn broadcast spreader, push-type broadcast spreader, and by fixed-
       wing aircraft. Typically one application is made per growing season.

Use Rates:

    •   Rates for all  salts and formulations are normalized to dicamba acid equivalents per acre
       (ae/A). Application rates range from 0.5 to 2.8 Ib ae/A.

III.    Summary of Dicamba Risk Assessment

       The following is a summary of EPA's human health and ecological risk findings and
conclusions for dicamba, as presented fully in the documents: "Dicamba: HED Chapter of the
Reregistration Eligibility Decision Document," written by C. Olinger, Y.Yang, T. Dole,  and M.
Hawkins (9/13/2005), and "Environmental Fate and Ecological Risk Assessment for the
Reregistration of Dicamba and Dicamba Sodium, Potassium, Diglycoamine, Dimethylamine, and
Isopropylamine Salts," written by W. Erickson, I. Abdel-Saheb, and S. Borges (11/15/05). There
were no public comments which required revisions to the risk assessments.

       The purpose of this section is to summarize the key  features and findings of the risk
assessments in order to help the reader better understand the risk management decision reached
by the Agency.  While the full risk assessments and related supporting documents are not
included in this document, they are available in the public docket at www.regulations.gov
(docket # EPA-HQ-OPP-2005-0479) and on the Agency's website at
http ://www. epa. gov/pesticides/reregistration/status.htm.

       A.   Human Health Risk Assessment

       The Agency  has conducted a human health risk assessment for dicamba for the purpose
of making a reregistration eligibility decision.  The Agency evaluated the toxicology, product
and residue chemistry, and occupational and residential exposure studies submitted for dicamba
and determined that the data are adequate to support a reregistration decision.  A summary of the
human health risk assessment findings and conclusions are below.

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              1.     Toxicology
The available toxicity data on dicamba are adequate to assess dicamba's hazard potential.  Table
1 below presents the acute toxicity profile for dicamba:
Table 1. Acute Toxicity Profile on Dicamba Acid
Guideline
870.1100
870.1200
870.1300
870.2400
870.2500
870.2600
Study Type
Acute oral toxicity / rat
Acute dermal toxicity / rat
Acute inhalation toxicity / rat
Primary eye irritation / rabbit
Primary dermal irritation / rabbit
Dermal sensitization / guinea pig
MRID
00078444
00241584
00263861
00241584
00237955
00263861
Results
LD50 => 2740 mg/kg
LD50 => 2000 mg/kg
LC50 => 5.3 mg/L
Irritant
Irritant
Non-Sensitizer
Toxicity Category
III
III
IV
II
II
-
See Table 2 for a summary of the toxicological endpoints used in the human health risk
assessment for dicamba.

FQPA Considerations

       Developmental studies were conducted on both rats and rabbits, following in utero and/or
pre-/post-natal exposure to dicamba. No evidence of increased susceptibility was observed. In
addition, no evidence of developmental anomalies of the fetal nervous system were observed in
the prenatal developmental toxicity studies in either rats or rabbits at maternally toxic doses of
up to 300 or 400 mg/kg/day.  Also, no evidence of behavioral or neurological effects on the
offspring was observed in the two-generation reproduction study in rats. Based on the weight of
evidence, a developmental neurotoxicity study (DNT)  is not required. Additionally, because the
dicamba dietary and residential risk assessments are not expected to underestimate exposure, the
special FQPA safety factor has been removed (reduced to IX) for the dicamba risk assessment.

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Table 2. Summary of Toxicological Endpoints Dicamba
Exposure Scenario
Factor Used in Risk Assessment
Study and Endpoint of Risk Assessment
Dietary Risk Assessment
Dietary (Acute)-
all populations
Dietary (Chronic)-
all populations
UF= 300x
aRID= l.Omg/kg/day
aPAD= 1.0 mg/kg/day
UF= lOOx
cRID= 0.45 mg/kg/day
cPAD= 0.45 mg/kg/day
MRID no: 42774104
Acute Neurotoxicity Study in Rats
The aRfd was determined based on a LOAEL of 300
mg/kg/day in the rat acute neurotoxicity study and an UF
of 300x (lOx for interspecies extrapolation, a lOx for
intraspecies variation, and a 3x for using a LOAEL,
instead of a NO AEL)
LOAEL = 300 mg/kg/day
Neurotoxicity signs such as impaired gaits and righting
reflex were seen in both male and females at the lowest
dose tested, 300 mg/kg/day
MRID no: 43137101
Multi-Generation Reproduction Study in Rats
The cRfD was established based on the NO AEL of 45
mg/kg/day in the multi-generation reproduction study and
an uncertainty factor of lOOx (lOx for interspecies
extrapolation, lOx for intraspecies variation).
NOAEL = 45 mg/kg/day
LOAEL = 136 mg/kg/day
Decreased pup weight was seen at the LOAEL of 136
mg/kg/day
Residential Risk Assessment (Adults and Toddlers)
Acute Oral
Exposure (Toddlers)
Dermal and
Inhalation
Short, Intermediate
& Long-term
Level of Concern MOE= 300
Level of Concern MOE= 100
15% dermal absorption factor
100% inhalation absorption
MRID no: 42774104
Acute Neurotoxicity Study in Rats
LOAEL = 300 mk/kg
MRID no: 43137101
Multi-Generation Reproduction Study in Rats
NOAEL = 45 mg/kg/day
LOAEL = 136 mg/kg/day
(Occupational) Non- Dietary Risk Assessment
Dermal-
Short &
Intermediate Term
(1-30 days)
Inhalation-
Short &
Intermediate Term
(1-30 days)
Cancer
Level of Concern= 100
15% dermal absorption factor
Level of Concern MOE= 100
100% inhalation absorption
Not likely to be carcinogenic to humans
MRID no: 43137101
NOAEL = 45 mg/kg/day
LOAEL =136 mg/kg/day
MRID no: 43137101
NOAEL = 45 mg/kg/day
LOAEL = 136 mg/kg/day
MRID no: 00146150
MRID no: 40872401
UF = uncertainty factor
aRfD = acute reference dose
LOAEL=lowest observed adverse effect level
MOE = margin of exposure
cRfD = chronic reference dose
NOAEL = no observed adverse effect level

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             2.     Dietary Exposure and Risk from Food and Drinking Water

       Dietary risk assessment incorporates both exposure to and toxicity of a given pesticide.
Dietary risk is expressed as a percentage of a level of concern. The level of concern is the dose
predicted to result in no unreasonable adverse health effects to any human population subgroup,
including sensitive members of such population subgroups. This level of concern is referred to
as the population adjusted does (PAD), which reflects the reference dose (RfD), either acute or
chronic, adjusted to account for the FQPA safety  factor.

       Estimated risks that are less than 100% of the PAD are below the EPA's level of concern.
The acute PAD (aPAD) is the highest predicted dose to which a person could be exposed on any
given day with no adverse health effect expected. The chronic PAD (cPAD) is the highest
predicted dose to which a person could be exposed over the course of a lifetime with no adverse
health effects expected.

                 a. Acute Dietary (Food and Drinking Water)

       Acute dietary risk is based on the quantity of food and water consumed in one day and
the estimated maximum residue values in food and water.  EPA evaluated the acute dietary risks
using the Dietary Exposure Evaluation Model (DEEM- FCID™, Version 2.03), which
incorporates food consumption data from the USDA's Continuing Surveys of Food Intakes by
Individuals (CSFII) from 1994-1996 and  1998.

       EPA conducted an unrefined, Tier 1 acute dietary food exposure/risk analysis for
dicamba using tolerance level residue values, default processing factors, and the assumption of
100% crop treated for all commodities. For Tier  1 analysis, which are based on upper-bound
pesticide residue value inputs (e.g., assuming 100% of registered crops are treated with the
pesticide, or that residues are present at tolerance level), EPA presents acute dietary results at the
95th percentile of exposure which provides a high-end estimate of risk  and is protective of the
general U.S. population and all population subgroups.

       The residues of concern for tolerance enforcement and risk assessment are dicamba, the
3,6-dichloro-5-hydroxybenzoic acid (5-OH dicamba) metabolite, and the 3,6-dichlorosalicylic
acid (DCSA) metabolite. The Agency assessed dietary risk from drinking water using the full
distribution of estimated residues in surface water, generated by PRZM-EXAMS models from
use of dicamba on sugarcane, which is the worst-case risk scenario.  Residues of dicamba acid
and it's degradate, DCSA, were combined for the risk assessment. The acute dietary estimates
are below the Agency's level of concern at the 95th exposure percentile for all population sub-
groups. When considering food alone, the most highly exposed subgroup for acute exposure is
children, aged 1-2, with 5.4% of the aPAD consumed.  When considering both food and water,
the most highly exposed subgroup  was infants with 11% of the aPAD consumed at the 95th
percentile.  See Table 3 for a  summary of dietary exposure and risk for dicamba.

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              b. Chronic Dietary (Food and Drinking Water)
       EPA conducted an unrefined Tier 1 chronic dietary food risk analysis using the average
consumption values for food and the average tolerance levels of those foods. Estimated
exposure to dicamba and its residues of concern for all population subgroups is well below the
level of concern. When considering food alone, or food and water, the most highly exposed
subgroup is children, aged 1-2, at 6.5% and 6.6% of the cPAD, respectively.

       Actual exposures to dicamba are likely to be considerably lower than these estimates.
These assessments assume all commodities have tolerance level residues; however, residues
sampled in most field trials were lower.  The assessments also assume 100% of all crops are
treated, but a screening level usage analysis indicates that the percent crop treated for most
commodities is less than 20%.  Only drinking water from surface water sources are considered,
but the model estimates for ground water are much lower than surface water estimates; therefore
the use of surface water is protective.  A summary of the dietary exposure and risk for dicamba is
presented in Table  3 below.
Table 3. Summary of Dietary Exposure and Risk for Dicamba: Food and Water
Population Subgroup
General U.S. Population
All Infants (< 1 year old)
Children 1-2 years old
Acute Dietary (95th Percentile)
Dietary exposure
mg/kg/day)
0.0435
0.108
0.0756
% aPAD
4.4
11
7.6
Chronic Dietary
Dietary Exposure
(mg/kg/day)
0.0118
0.0199
0.0297
% cPAD
2.6
4.4
6.6
       For additional information, please see Section 5.2 of the FLED risk assessment.

              3.     Residential Exposure and Risk

       Both spot and broadcast treatments are permitted by product labels.  Exposures from
lawn treatment are expected to be short-term in duration because the label allows only two
broadcast treatments per year and use directions for spot treatments recommend repeat
applications after two to three weeks for hard-to-kill weeds.

       Non-cancer risk estimates (such as residential estimates) are expressed as a margin of
exposure (MOE) which is a ratio of the dose from a toxicological study selected for risk
assessment, typically a NOAEL, to the predicted exposure. Estimated MOEs are compared to a
level of concern which reflects the dose selected for risk assessment and uncertainty factors
(UFs) applied to that dose. The standard UF is lOOx, which includes lOx for interspecies
extrapolation (to account for differences between laboratory animals and humans) and  lOx for
intraspecies variation (to account for differences within a species of laboratory animal).
Additional uncertainty or safety factors may also be applied.  In the case of dicamba, EPA's level
of concern for  residential exposure is an MOE of 100 for short-, intermediate-, and long-term
residential risk assessments for both dermal and inhalation routes of exposure. EPA's level of
concern for acute exposures is an MOE of 300, which incorporates the standard uncertainty

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factors and a 3X for using a LOAEL rather than a NOAEL as the endpoint. EPA determined that
the available data support the removal of the default 10X FQPA safety factor. Thus, scenarios
that yield MOEs that are less than 300 for acute exposure and less than 100 for all other
exposures may trigger concern. No scenarios resulted in exceedances of the levels of concern.

                     a. Residential Handler Exposure and Risk

       The handler exposure data were taken from the Pesticide Handler Exposure Database
(PHED) and the Outdoor Residential Exposure Task Force (ORETF) data.  The residential
handler risks were calculated using standard assumptions, the highest quality unit exposure data
available,  and the maximum label application rates. All the MOEs for residential handler
exposure are greater than the level of concern MOEs of 300 for acute exposures and 100 for
short-term exposures, and therefore the risks are below the EPA's level of concern. Seven
scenarios for residential handling and application of dicamba were assessed resulting in MOEs
ranging from 3,800 to 62,000.

                    b. Residential Postapplication Exposure and Risk

       Residential postapplication exposure data were taken from four turf transferable residue
studies. All of the studies were reviewed by the Agency and were found to meet the guidelines
for postapplication exposure monitoring. Acute MOEs for toddlers ingesting granules resulted in
acute MOEs > 1500. Please see the HED risk assessment for more details on granular ingestion.
The acute MOEs for toddlers playing on turf are greater than the MOE of 300 for dermal and
incidental ingestion risk, and are below EPA's level of concern.  Typically, the Agency does not
assess inhalation risk for postapplication exposures since inhalation is not considered to be an
important postapplication route of exposure for most active ingredients.  All short-term MOEs
for both adults and toddlers are greater than 100 and are below the EPA's level of concern. A
summary of the MOE estimates is included in Tables 5 and 6.
Table 5. Acute Dicamba MOEs for Turf Exposures (Application Rate = 1.0 Ib ae/acre)
Scenario
TTR
(ug/cm2)
TC
(cm2/hr)
Dermal
MOE
Hand-to-
Mouth
MOE
Object-to-
Mouth
MOE
Soil
Ingestion
MOE
Total
MOE
Toddlers
Playing
0.29
5,200
9,900
20,000
80,000
5,900,000
6,100
Target MOE is 300
Table 6. Short Term Dicamba MOEs for Turf Exposures (Application Rate = 1.0 Ib ae/acre)
Scenario
TTR
(ug/cm2)
TC
(cm2/hr)
Dermal
MOE
Hand-to-
Mouth
MOE
Object to
Mouth
MOE
Soil
Ingestion
MOE
Total
MOE
Toddlers
Playing
0.060
5,200
7,200
7,200
29,000
2,100,000
3,200
Adult
Yard work
Golf
0.060
0.060
14,500
500
12,000
170,000
N/A
Target MOE is 100
TTR = turf transferable residues                              TC = transfer coefficient
For more residential exposure information, please see the HED risk assessment.
                                           10

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              4.     Aggregate Exposure and Risk

       The FQPA amendments to the Federal Food, Drug and Cosmetic Act (FFDCA, Section
408(b)(2)(A)(ii)) require "that there is a reasonable certainty that no harm will result from
aggregate exposure to the pesticide chemical residue, including all anticipated dietary exposure
and other exposures for which there is reliable information."

       An aggregate risk assessment looks at the combined risk from dietary exposure (food and
drinking water pathways) as well as exposure from non-occupational sources (e.g., residential
uses).  Acute aggregate exposures (less than one day) may result from consuming treated food or
drinking water. Acute aggregate exposures may also result from residential exposures such as
adults doing yard work or playing golf on treated turf, or from children playing on treated turf.
Typically the Agency does not aggregate acute dietary exposures with acute residential
exposures, because it is very unlikely that high-end food and water exposures will occur on the
same day as the maximum residential exposures. Therefore, acute aggregate risks for dicamba
are equal to the acute dietary risks. As noted above, the acute dietary risk estimates for the U.S.
population and all subgroups are well below the Agency's level  of concern. The most highly
exposed subgroup is infants at  11% of the aPAD.

       The short-term aggregate assessment considered exposures from food, drinking water,
residential handler, and residential postapplication activities. Average food and water exposure
estimates were used in the assessment. The residential handler scenario that resulted in the
highest exposures, adults who mix/load/apply with a (mix-your-own) hose-end sprayer, was used
in the adult aggregate assessment.  The exposure from the yard work postapplication scenario
was used for the adult assessment, and the exposure from the toddler playing on turf scenario
was used in the child assessment.  The MOEs for all scenarios for the short-term aggregate
assessment range from 1,030 to 2,720.  Since the MOEs are greater than 100, the risks are below
the EPA's level of concern.

       There are no residential scenarios that would result in intermediate- or long-term
residential exposures. Therefore no intermediate-term aggregate assessment was necessary, and
chronic aggregate risks are equal to chronic dietary risks.  As discussed above, the chronic
dietary aggregate risk estimates for the U.S. population and all subgroups are well below the
Agency's level of concern.  The most highly exposed population subgroup is children, aged 1-2
years, at 6.6% of the cPAD.

              5.     Occupational Exposure and Risk

       Workers can be exposed by mixing, loading, or applying dicamba or by entering a
previously treated site.  Like residential risk, worker risk is also  measured by MOEs.  For
handlers, the Agency initially assesses risk at "baseline" which considers an individual's  normal
work clothing (e.g., long sleeve shirt and long pants), no gloves, and no respirator. If there is  a
concern at baseline, the Agency considers the use of protective measures (e.g., personal
protective equipment and engineering controls) to lower the risk. Personal protective equipment
(PPE) can include an additional layer of clothing, chemical-resistant gloves, or a respirator.
                                            11

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Common examples of engineering controls include enclosed tractor cabs, closed loading
systems, and water-soluble packaging.

                    a. Occupational Handler Risk

       The handler exposure data were taken from the Pesticide Handler Exposure Database
(PHED), the Outdoor Residential Exposure Task Force (ORETF) and the California Department
of Pesticide Regulations (CA DPR).  The PHED data were used primarily to assess the large
scale agricultural and forestry scenarios and the ORETF data were used for evaluating lawn care
scenarios.  The CA DPR data were used to assess the backpack applicator scenario for the forest
site preparation use, which includes multiple applicators that are supplied by a nurse tank.

       Several handler exposure scenarios were assessed, and can be found in the human health
risk assessment.  The MOEs for the baseline  exposure scenarios that are below the Agency's
level of concern are shown in Table 7 below. With the addition of chemical resistant gloves, all
of the occupational handler scenarios listed below have MOEs above 100, and are not of risk
concern.  All other mixer, loader, or applicator scenarios had an MOE greater than 100 for
workers at wearing single layer of clothing and no chemical resistant gloves (baseline).
                                           12

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Table 7. Dicamba Handler Combined MOEs
Exposure Scenario



Crop or Site



Application
Rate
(Ib ae/acre)

Acres/
Day


Margins of Exposure

Baseline


Baseline +
Gloves
Mixer/Loader (M/L)
M/L WP for turfgun application
M/L Liquids for Aerial
M/L Liquids for Aerial
M/L Liquids for Aerial
M/L Liquids for Groundboom
M/L Liquids for Groundboom
M/L Liquids for Groundboom

M/L Liquids for Groundboom
M/L Liquids for ROW Sprayer
M/L Liquids for Turf Gun
M/L Liquids for Backpack
Application
Backpack Application
Turfgun Application
M/L/A Wettable Powder with
Turfgun
M/L/A WDG with Turfgun
M/L/A Liquid Flowables with
Turfgun
M/L/A Liquids with Backpack
Sprayer
Load/ Apply Granules with a Push
Cyclone
Turf
Sugar Cane
Soybeans, RPF
Small Grains,
Sugar Cane
Soybean, RPF
Small Grains,
Corn
Sod Farms
ROW
Turf
Forest Site Prep
Forest Site Prep
Turf
Turf

Turf
Turf

ROW, RPF

Turf


1
2.8
2
0.5
2.8
2
0.5

1
2
1

2







2

1

100
1200
1200
1200
200
200
200

80
50
100

40
4
5
5

5
5

4

5

53
2
3
12
13
18
72

90
72
72

90
ND
ND
ND

ND
ND

ND

ND

>1000
200
280
>1000
>1000
>1000
>1000

>1000
>1000
>1000

>1000
410
>1000
>1000

>1000
>1000

970

>1000

RPF= Rangeland, Pastures, and Fallow Land              ND= Not Determined
ROW= Right of Way
                     b. Occupational Postapplication Risk

       Postapplication dicamba exposures can occur in the agricultural environment when
workers enter fields recently treated with dicamba to conduct tasks such as scouting and
irrigation. Because dicamba is typically applied once per season and the relevant agricultural
scenarios occur for only a few weeks per year, it is anticipated that dicamba exposures would be
primarily short-term, and, more rarely, intermediate-term.

       Occupational postapplication exposure data were taken from the three turf transferable
residue studies submitted.  All of the short- and intermediate-term MOEs are above 100 on day
of treatment, and therefore risks are not of concern. The current Worker Protection Standard
(WPS) Restricted Entry Interval (REI) for dicamba is 24 hours.
                                            13

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             6.      Incidents reports

       The incident analysis was prepared under a separate memo by Monica Spann, M.P.H.,
and Jerome Blondell, PhD., of the Office of Pesticide Programs. Only those incidents involving
products with dicamba as the sole active ingredient in a product were considered. There was
only a single report in the Incident Data System of minor eye irritation resulting from dicamba
flaked dust falling into a person's eye.

       Poison Control Center data for the years 1993 through 2003 indicate that there were 24
occupational exposures to dicamba.  Of these 24 cases, three had a moderate medical outcome
and one was considered a major medical outcome.  The major outcome case was a 15 year old
who was exposed in the eye and experienced blurred vision, irritation, non-reactive pupils, and a
visual defect.

       The Poison Control Center data indicated that there were 146 non-occupational (i.e.,
residential) exposure cases and 13 of these cases were classified as a moderate medical outcome
with primary symptoms of eye irritation, corneal abrasion, coughing, and difficulty breathing.
One case with major medical outcome was a 16 year-old with chest pain, dysrhythmia,
tachycardia (fast pulse), multiple seizures, and coma after inhalation. However, there were no
other cases with such serious symptoms among the 146 exposures.

       No incidents of dicamba poisoning were reported in California from 1982 through 2003.

       B.     Environmental Risk Assessment

       The Agency has conducted an environmental assessment for dicamba for the purpose of
making a reregistration decision.  The Agency evaluated environmental fate and ecological
studies submitted for dicamba and determined that the data are adequate to  support a
reregistration decision. More in-depth details of the studies used to develop the risk assessments
and to support the guideline studies are  provided in "Environmental Fate and Ecological Risk
Assessment for the Reregistration of Dicamba and  Dicamba Sodium, Potassium, Diglycoamine,
Dimethylamine, and Isopropylamine Salts," written by W. Erickson, I. Abdel  Saheb, and S.
Borges (11/15/05), which is found in the electronic docket.  A summary of the environmental
risk assessment findings  and conclusions is provided below.

             1.     Environmental Fate and Transport

       The Agency bridged the environmental fate data requirements for the dicamba sodium
and potassium salts, dimethylamine salt (DMA), isopropylamine salt, and diglycoamine salt
(DGA) to the dicamba acid since the dicamba salts rapidly convert to the free  acid of dicamba.
Dicamba acid is very soluble and very mobile in laboratory  soil studies.

       Aerobic soil metabolism is the main degradative process for dicamba acid.  The observed
half-life for dicamba acid was six days with formation of the non-persistent degradate DCSA.
DCSA degraded  at approximately the same rate as dicamba with the final metabolites being
                                          14

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carbon dioxide and microbial biomass. Dicamba is stable to abiotic hydrolysis at all pH levels
and photodegrades slowly in water and in soil.

       Under anaerobic soil conditions, dicamba has a half-life of 141 days. The major
degradate under anaerobic conditions was DCSA, which is persistent in anaerobic systems.
There are no data for the aerobic aquatic metabolism in dicamba; however,  supplemental
information indicates that dicamba degrades more rapidly in aquatic systems when sediment is
present.

       Based on fate characteristics, dicamba and DCSA would be somewhat persistent in
aerobic and anaerobic conditions and would be expected to be persistent in groundwater.

             2.     Environmental Effects

                    a. Ecological Risk Estimation

       The Agency's ecological risk assessment compares toxicity endpoints from ecological
toxicity studies to estimated environmental concentrations (EECs) based on environmental fate
characteristics and pesticide use data. To evaluate the potential risk to non-target organisms
from the use of dicamba products, the Agency calculates a Risk Quotient (RQ), which is the ratio
of the EEC to the most  sensitive toxicity endpoint values, such as the median lethal dose (LDso)
or the median lethal concentration (LCso). These RQ values are then compared to the Agency's
levels of concern (LOCs), indicating whether a pesticide, when used as labeled, has the potential
to cause adverse effects on non-target organisms (see Table 8 below). When the RQ exceeds the
LOG for a particular category, 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 levels
of certainty and uncertainty in the assessment. EPA further characterizes ecological risk based
on any reported incidents to non-target terrestrial or aquatic organisms in the field (e.g., fish or
bird kills).
Table 8. EPA's Levels of Concern and Associated Risk Presumptions
Risk Presumption
Acute Risk - there is potential for acute risk
Acute Endangered Listed 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
LOC
Plants
1
1
Not Assessed
                    b. Aquatic Organism Risk

       The Agency used modeling to derive estimated environmental concentrations (EECs) for
dicamba in surface water to represent a variety of aquatic habitats, such as ponds adjacent to
treated fields, which are relevant to risk assessment for aquatic animals.
                                           15

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       Available acute toxicity data for aquatic species indicate that dicamba is slightly toxic to
fish and invertebrates with LCso and the median effect concentration (ECso) values for fish and
invertebrates of 28 mg/L and 34.6 mg/L respectively.  There were no exceedances of the aquatic
acute risk, endangered species, and chronic risk LOCs for fish and invertebrates with all RQs <
0.01, indicating that freshwater fish and invertebrates  inhabiting surface waters adjacent to a
treated field would not be at risk of adverse acute effects from use of dicamba.  However,  since
there are no chronic studies for fish and invertebrates which measure effects such as survival,
growth, and reproduction offish and invertebrates, chronic  risk to aquatic organisms is an
uncertainty. Likewise, due to insufficient invertebrate toxicity data, risk to sediment-dwelling
benthic organisms remains an uncertainty.

       Toxicity studies indicate that dicamba is not toxic to aquatic vascular plants with the ECso
for the freshwater vascular plant of 3.25 mg/L.  There were no exceedances of the acute risk
LOG for freshwater vascular plants. However, the LOCs for non-vascular plants were exceeded
for the application rates 2.8 Ibs ae/acre and 2.0 Ibs ae/acre.  Consequently, aquatic non-vascular
plants would potentially be at risk for adverse effects to growth and development from use of
dicamba at these labeled rates.
Table 9. Summarized Acute Aquatic Plant Risk Quotients for Dicamba Acid
Scenario
Michigan asparagus
(0.5 Ibs ae/A)
Texas pasture
(2.0 Ibs ae/A)
Florida sugarcane
(2.8 Ibs ae/A)
Listed
freshwater vascular
Ground app. <1
Aerial app . <1
Ground app. <1
Aerial app. <1
Ground app. <1
Aerial app. <1
Non-listed
Freshwater vascular
<1
<1
<1
<1
<1
<1
Freshwater
non-vascular
<1
<1
1.39
1.38
2.79
2.72
All aquatic plant RQs from other dicamba uses at rates of less than 2 Ib ae/A were less than 1 and
are below EPA's level of concern.
Birds
              c. Terrestrial Organism Risk
       Dicamba salts are categorized as practically non-toxic to avian species based on dietary
studies. However, oral gavage studies indicate dicamba acid was moderately toxic to bobwhite
quail and slightly toxic to mallard ducks.

       The acute risk LOG was exceeded for small birds consuming mean residues of dicamba
on short grass, tall grass, broadleaf forage, and small insects, and for large birds consuming short
grass.  See Table  10 for a listing of RQs calculated based on predicted mean residues from
application of dicamba at various rates. Levels of concern are set at 0.5 for acute risk and 0.1 for
acute endangered species risk.
                                            16

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Table 10. Avian Acute Risk Quotient Summary from Predicted Mean Residues
Food type
short grass
tall grass
broadleaf forage,
small insects
fruit, pods, seeds,
large insects
Weight
class (g)
20
100
1000
20
100
1000
20
100
1000
20
100
1000
RQs
2.8 Ibs ae/acre
2.04
0.91
0.29
0.86
0.39
0.12
1.08
0.48
0.15
0.17
0.08
0.02
2.0 Ibs ae/acre
1.46
0.65
0.21
0.62
0.28
0.09
0.77
0.35
0.11
0.12
0.05
0.02
1.0 Ibs ae/acre
0.72
0.32
0.10
0.30
0.14
0.04
0.38
0.17
0.05
0.06
0.03
0.01
0.75 Ib ae/acre
0.54
0.24
0.08
0.23
0.10
0.03
0.28
0.13
0.04
0.04
0.02
0.01
       The Agency assesses acute avian risks from granular formulations differently than for
liquid formulations with granular RQ's based on a ratio of the LD50 and the amount of active
ingredient applied to one square foot of ground.  Dicamba has several products which are
formulated with fertilizers and the avian  and mammalian risks from these products were assessed
after the risk assessment document was completed.  For products that are applied at 0.29 Ib ae/A
or greater, acute risk LOCs are exceeded for 20 gram birds with RQs ranging up to 7.5 for a 2.0
Ib ae/A application. Please see the EFED's Response to Comments document for the complete
granular assessment.

       The Chronic Risk LOG was not exceeded for any use with the maximum RQ of 1.0.
Consequently, birds are not expected to be at risk from chronic developmental/reproductive
effects when exposed to dicamba as a result of the labeled uses of the pesticide.

Mammals

       Dicamba acid is classified as practically non-toxic to small mammals on an acute oral
basis.  There were no exceedances of any acute LOG from predicted mean residues.

       The Agency assesses acute mammalian risks from use of granular formulations
differently than the use of liquid  formulations. Granular RQ's are based on the ratio of the LD50
and the amount of active ingredient applied to one  square foot of ground. Dicamba has several
products which are formulated with fertilizers.  Avian and mammalian risks from these products
were assessed after the risk assessment document was posted in EPA's public docket. For
products that  are applied at 1.0 and 2.0 Ib ae/A, mammalian endangered species LOCs are
exceeded for  15 gram mammals with RQs of 0.1 and 0.2, respectively.  This is solely based on
EPA's screening-level assessment. The assessment for larger mammals and lower application
rates resulted in no exceedances.  See EFED's Response to Comments document for the
complete granular assessment.

       The Chronic Risk LOG of 1.0 was exceeded for mammals consuming maximum and
mean predicted dicamba residues on short grass for application rates greater than or equal to 0.75
                                          17

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Ib ae/A. For a listing of RQs for mean foliar residues on different food items, please see Table
11.  For tall grass, broadleaf forage, and small insects, the chronic risk LOG was exceeded as
well.  There were no exceedances of the chronic risk LOG for mammals consuming the
maximum residues on fruit, seeds, and large insects.  As a result, mammals could potentially be
at risk for developmental/reproductive effects or for direct effects on foraging behavior when
chronically exposed to dicamba as a result of the labeled uses of the herbicide.
Table 11. Mammalian Chronic Risk Quotient Summary from Predicted Mean Residues
Food type
short grass
tall grass
broadleaf forage,
small insects
fruit, pods, seeds,
large insects
Weight
class (g)
15
35
1000
15
35
1000
15
35
1000
15
35
1000
RQs
2.8 Ib ae/acre
2.29
1.96
1.03
0.97
0.83
0.44
1.21
1.04
0.55
0.19
0.16
0.08
2.0 Ib ae/acre
1.63
1.40
0.74
0.69
0.59
0.31
0.86
0.74
0.39
0.13
0.12
0.06
1.0 Ib ae/acre
0.82
0.70
0.37
0.35
0.30
0.16
0.43
0.37
0.20
0.07
0.06
0.003
0.75 Ib ae/acre
0.61
0.53
0.28
0.26
0.22
0.12
0.32
0.28
0.15
0.05
0.04
0.02
       Dicamba is an herbicide; as expected, terrestrial non-target plants are potentially at risk
from its use.  Seedling emergence and vegetative vigor are impacted by exposure to dicamba
acid; adverse effects include stunting, chlorosis,  and plant death. Plant LOCs are 1.0 for both
non-listed and listed plants. Dicots are much more sensitive to dicamba than monocots. See
Table 12 for a listing of RQs.
Table 12. Summarized Terrestrial Plant Acute Risk Quotients
Scenario
Acute Non-listed RQs
Adjacent to
treated sites
Semi-aquatic
areas
Drift
Acute Listed RQs
Adjacent to
treated sites
Semi-aquatic
areas
Drift
Sugarcane (2.8 Ibs ae/A)
Ground spray application
Monocot
Dicot
3.96
62.22
33.68
528.89
0.19
4.12
5.25
76.36
44.63
649.09
0.22
7.00
Aerial spray application
Monocot
Dicot
5.28
82.96
23.11
362.96
0.93
20.59
7.00
101.82
30.63
445.45
1.08
35.00
Hay, pasture/rangeland, soybean and agricultural fallowland (2.0 Ibs ae/A)
Ground spray application
Monocot
Dicot
1.42
22.22
12.03
188.89
0.07
1.40
1.88
27.27
15.94
231.82
0.08
2.50
Aerial spray application
Monocot
Dicot
1.89
29.63
8.25
129.63
0.33
7.35
2.50
36.36
10.94
159.09
0.38
12.50
                                           18

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Table 12. Summarized Terrestrial Plant Acute Risk Quotients
Scenario
Acute Non-listed RQs
Adjacent to
treated sites
Semi-aquatic
areas
Drift
Acute Listed RQs
Adjacent to
treated sites
Semi-aquatic
areas
Drift
Corn (0.751bs as/A)
Ground spray application
Monocot
Dicot
1.06
16.67
9.02
141.67
0.05
1.10
1.41
20.45
11.95
173.86
0.06
1.88
Aerial spray application
Monocot
Dicot
1.42
22.22
6.19
97.22
0.25
5.50
1.88
27.27
8.20
119.32
0.29
9.38
       3.      Ecological Incidents

Dicamba acid: Thirty-five ecological incidents attributed to dicamba use have been recorded in
the Ecological Incident Information System (EIIS) as of June 1, 2005.  Incidents reported include
terrestrial, plant, and aquatic impacts.  Although the database lists a terrestrial mammalian
incident in Utah where dicamba was applied, the database states that dicamba is "unlikely" to
have caused the incident. Impacts to plants included a wide range of crops (soybeans, corn,
wheat) as well as non-agricultural application. The specific impacts varied from browning and
plant damage to mortality of all plants within the treated area.  Aquatic impacts consist of two
fish kill incidents associated with agricultural and residential turf application.

Dicamba Sodium Salt: Fifteen incidents attributed to dicamba sodium salt use have been
recorded in the EIIS as of June 1, 2005. All reported incidents were associated with plant
damage to crops including sorghum, soybean, corn, and sugar beets.

Dicamba Dimethylamine Salt: Forty-six incidents attributed to dicamba dimethylamine salt use
have been recorded in the EIIS as of June 1, 2005. Incidents reported include plant and aquatic
impacts.  The majority of incidents to plants (40 of 45) were associated with residential turf
application and ranged from browning to mortality. Agricultural application resulted in plant
damage to cotton, corn and soybeans. The single reported aquatic incident was a fish kill of
unknown magnitude resulting from turf application.

Dicamba Potassium Salt: Three incidents attributed to dicamba, potassium salt use have been
recorded in the EIIS as of June 1, 2005. There were 2 incidents reported of impacts to plants,
both associated with application on corn resulting in plant damage. The sole aquatic impact was
associated with agricultural application which resulted in the mortality of 2,000 perch.

Dicamba Diglycoamine Salt: Two incidents attributed to dicamba, diglycoamine salt use have
been recorded in the EIIS as of June 1, 2005. Both incidents were associated with impacts to
plants (soybeans) which resulted in plant damage.
                                           19

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       4.      Risk to Endangered Species

       The Agency's screening level ecological risk assessment for endangered species results
in the determination that dicamba will have no direct acute effects on threatened and endangered
freshwater fish, estuarine fish, and aquatic invertebrates.  However, the assessment indicates that
dicamba has the potential for causing risk to endangered birds, mammals, and non-target plants.
Further, potential indirect effect to any species dependent upon a species that experiences effects
cannot be precluded from use of dicamba. These findings are based solely on EPA's screening
level assessment and do not constitute "may effect" findings under the Endangered Species Act.
Chronic RQs exceeded LOCs for endangered mammals at all application rates modeled. Acute
LOCs were exceeded for endangered birds at all application rates. LOCs were exceeded for
terrestrial plants adjacent to treated areas and in semi-aquatic areas at all application rates.

IV.    Risk Management, Reregistration, and Tolerance Reassessment Decision

       A.     Determination of Reregistration Eligibility

       Section 4(g)(2)(A) of FIFRA calls for the Agency to  determine, after  submission of
relevant data concerning an active ingredient, whether or not products containing the active
ingredient are eligible for reregistration.  The Agency has previously identified and required the
submission of the generic (i.e., active ingredient-specific) data required to support reregistration
of products containing dicamba  as an active ingredient.  The Agency has reviewed these generic
data, and has determined that the data are sufficient to support reregistration of all products
containing dicamba.

       The Agency has completed its review of submitted data and its assessment of the dietary,
residential, occupational, and ecological risks associated with the use of pesticide products
containing the active ingredient  dicamba. Based on these data, the Agency has sufficient
information on the human health and ecological effects of dicamba to make its decision as part of
the reregistration process under FIFRA, as amended by FQPA. The Agency has determined that
products containing dicamba will be eligible for reregistration provided that (i) required product
specific data are submitted,  (ii) the risk mitigation measures outlined in this document are
adopted, and  (iii) label amendments are made to reflect these measures. Needed label changes
and language are listed in Section V. Appendix A is a detailed table listing all dicamba uses that
are eligible for reregistration. Appendix B identifies generic data requirements that the Agency
reviewed as part of its determination of the reregistration eligibility of dicamba, and lists the
submitted studies the Agency found acceptable. Data gaps are identified as either outstanding
generic data requirements that have not been satisfied with acceptable data or additional data
necessary to confirm the decision presented here.

       Based on its evaluation of dicamba, the Agency has determined that dicamba products,
unless labeled and used as specified in this document, would present risks inconsistent with
FIFRA and FFDCA. Accordingly, should a registrant fail to implement any of the risk
mitigation measures identified in this document, the Agency may take regulatory action to
address the risk concerns from the use of dicamba. If all changes outlined in  this document are
incorporated into the product labels, then all current risks for dicamba will be adequately
                                           20

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mitigated for the purposes of this interim determination under FIFRA. Additionally, once an
endangered species assessment is completed, further changes to these registrations may be
necessary as explained in Section IV.D.S.a of this document.

       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 dicamba.  During the public
comment period on the risk assessments, which closed on February 27, 2006, the Agency
received five comments from five sources: BASF, the University of Hawaii at Manoa,
Department of the Environment San Francisco, The Thurston County, Washington, Public
Health and Social  Services Department, and a citizen.  BASF's comments pertained to ecological
and water risks in the dicamba science chapters. The City of San Francisco and Thurston County
both emphasized the importance of risk reduction measures for dicamba through alternative
pesticides. The University of Hawaii's comment was  in support of benefits of use of dicamba on
golf courses, seed  corn, sugarcane, and asparagus. The citizen comment pertained to adverse
effects from using dicamba.  The comments in their entirety are available in the public docket
(EPA-HQ-OPP-0479) at http://www.regulations.gov.  A detailed Response to Comments
document is available in the public docket as well.

       C.     Regulatory Position

             1.     Food Quality Protection Act Findings

                    a. "Risk Cup" Determination

       Dicamba tolerances were reassessed in 2000 when a new food use was added.  However,
as part of the FIFRA reregistration, EPA assessed the risks associated with this pesticide. EPA
has determined that aggregate risk from food, drinking water, and residential exposures to
dicamba is within  is own "risk cup"  and that the human health risks from these combined
exposures are within acceptable levels. In other words, EPA has  concluded that the tolerances
for dicamba  meet FQPA safety standards. In reaching this determination,  EPA has considered
the available information on the special sensitivity of infants and children, as well as aggregate
exposure from food, drinking water, and residential uses. The FQPA Safety Factor has not been
retained for dicamba because acceptable developmental and reproduction studies have been
submitted and reviewed, there is a low concern and no residual uncertainties for pre- and
postnatal toxicity,  and the dietary and the residential assessments are not expected to
underestimate exposure.

             2.     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
                                          21

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(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 for additional hormone systems may be added to the Endocrine Disrupter Screening
Program (EDSP).

       In the available toxicity studies on dicamba, there was no evidence of endocrine
disruption effects. When additional appropriate screening and/or testing protocols being
considered under the Agency's EDSP have been developed, dicamba may be subjected to further
screening and/or testing to better characterize effects related to endocrine disruption

             3.     Cumulative Risks

       Unlike other pesticides for which EPA has followed a cumulative risk approach based on
a common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding
as to dicamba and any other substances. For the purposes of this reregistration decision,
therefore, EPA has not assumed that dicamba has a common mechanism of toxicity with other
substances.

             4.     Tolerance Reassessment Summary

       The completion of the dicamba RED does not result in any additional tolerances being
reassessed. All 60 existing tolerances were reassessed at the time a new food use was
established for dicamba.  Please see Federal Register Notice 65 FR 33709 (May 24, 2000), for
further reference.

       D.    Regulatory Rationale

             1.     Human Health Risk Assessment

                    a.  Aggregate Risk

       As discussed in Chapter 3, aggregate risk refers to the combined risk from food, drinking
water, and residential exposures.  In addition, aggregate risk can result from one-time (acute),
short-term and/or chronic exposures. For dicamba, aggregate risk for food, drinking water, and
residential exposures are below the Agency's level of concern for acute, short term, and chronic
exposure. No mitigation is necessary for dietary, drinking water, or residential exposure to
dicamba.
                    b.  Occupational Risk

                           (i)     Handlers
       Due to risk exceedances for scenarios such as mixing/loading/applying,  dicamba labels
must be amended to add chemical resistant gloves to all mixers,  loaders, applicators, and any
                                          22

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other handlers.  The addition of gloves to the assessment resulted in MOEs > 280 for all
exposure scenarios.
                           (ii)    Postapplication

       There are no short/intermediate re-entry risks for dicamba on the day of application.
However, due to a toxicity category II for acute eye irritation, the current REI of 24 hours will
remain unchanged.

       2.      Environmental Risk Mitigation

       Because of the potential non-target animal and plant risks, the Agency is requiring that
the maximum application rate be reduced to 1.0 Ib ae/acre for a single application and reduced to
2.0 Ib ae/acre per year for all use patterns. This will result in lowering the potential risks of
concern to aquatic plants. This rate reduction will also lower acute risks to all animals (except
small herbivorous birds), as well as chronic risk to mammals.  Assessed risks to terrestrial plants
will be lowered, but not eliminated.

                     a. Spray Drift

       The Agency has been working with the Spray Drift Task Force, EPA Regional Offices
and State Lead Agencies for pesticide regulation and other parties to develop the best spray drift
management practices. The Agency has completed its evaluation of the new data base submitted
by the Spray Drift Task Force, a membership of U.S. pesticide registrants, and is developing a
policy on how to appropriately apply the data and the AgDRIFT computer  model to its risk
assessments for pesticides applied by air, orchard airblast and ground hydraulic methods. After
the policy is in place, the Agency may impose further refinements in spray drift management
practices to reduce off-target drift and risks associated with aerial as well as other application
types where appropriate.

       From its assessment of dicamba, as summarized in this document, the Agency concludes
that no specific additional drift mitigation measures are needed at this time.  In the future,
dicamba product labels may need to be revised to include additional or different drift label
statements.  The Agency encourages the inclusion of best management practices on labels to
reduce spray drift.

                     b. Endangered  Species Considerations

       The Agency's  screening level ecological risk assessment for endangered species results
in the determination that dicamba will have no direct acute effects on threatened and endangered
freshwater fish, estuarine fish, and aquatic invertebrates.  However, the Agency's level of
concern was exceeded for endangered birds, mammals, and non-target plants. Further, potential
indirect effect to any species dependent upon a species that experiences effect cannot be
precluded from use of dicamba. These findings are based solely on EPA's screening level
assessment and do not constitute "may effect" findings under the Endangered Species Act.
Chronic RQs exceeded LOCs for endangered mammals at all application rates modeled. Acute
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LOCs were exceeded for endangered birds at all application rates. LOCs were exceeded for
terrestrial plants adjacent to treated areas and in semi-aquatic areas at all application rates.

       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 and considers it 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 aspects
of the particular species, as part of a refined species-specific analysis. When conducted, this
species-specific analysis will take into consideration any regulatory changes recommended in
this RED 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
dicamba, 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 dicamba "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 RED will reduce the
likelihood that endangered and threatened species may be exposed to dicamba at levels of
concern. EPA is not requiring specific  dicamba 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.

V.     What Registrants Need to Do

       The Agency has determined that dicamba is eligible for reregistration; however,
additional data are required to confirm this decision.  In the near future, the Agency intends to
issue Data Call-In Notices (DCIs) requiring product specific data and generic (technical grade)
data.  Generally, registrants will have 90 days from receipt of a DCI to complete and submit
response forms or request time extension and/or waiver requests with a full written justification.
For product specific data, the registrant will have 8 months to submit data and amended labels.
For generic data, due dates can vary depending on the specific studies being required.  Below are
tables of additional generic data that the Agency intends to require for dicamba to be eligible for
reregistration.
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       A.    Manufacturing Use Products

             1.     Additional Generic Data Requirements

       The generic data base supporting the reregistration of dicamba for the above eligible uses
has been reviewed and determined to be substantially complete. However, the data listed below
are necessary to confirm the reregistration eligibility decision documented in this RED.

Guideline    Study Description

Residue Chemistry

860.1340     Residue Analytical method for barley grain and  straw, wheat straw, and soybean
             seeds.

860.1360     Multiresidue methods data for the dicamba metabolites of concern (5-OH
             dicamba and DCSA).

860.1380     Storage stability data for sugarcane molasses and animal commodities.

860.1500     Crop Field Trials for soybean forage and hay (if no feeding restrictions appear on
             the label).

860.1500     Crop Field Trials for sugarcane

Ecological Exposure

850.4225     Seedling emergence for end use products.

850.4250     Vegetative vigor studies for end use products

            2.      Labeling for Manufacturing-Use Products

       To ensure compliance with FIFRA, manufacturing use product (MUP) labeling should be
revised to comply with all current EPA regulations, PR Notices, and applicable policies.

       B.    End-Use Products

            1.      Additional Product-Specific Data Requirements

       Section 4(g)(2)(B) of FIFRA calls for the Agency to obtain any needed product-specific
data regarding the pesticide after a determination of eligibility has been made.  The Registrant
must review previous data submissions to ensure that they meet current EPA acceptance  criteria
and if not, commit to conduct new studies. If a registrant believes that previously submitted data
meet current testing standards, then the study MRID numbers should be cited according to the
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instructions in the Requirement Status and Registrants Response Form provided for each
product.  The Agency intends to issue a separate product-specific data call-in (PDCI), outlining
specific data requirements.

             2.     Labeling for End-Use Products

       In order to be eligible for reregistration, amend all product labels to incorporate the risk
mitigation measures outlined in the Risk Mitigation Summary section.  The following table
describes how language on the labels should be amended.

       Conclusions

       The Agency is issuing this Reregistration Eligibility Decision (RED) document for
dicamba, as announced in a Notice of Availability published in the Federal Register.  This
RED document includes guidance and time frames for complying with any required label
changes for products containing dicamba.  The Agency has determined that all currently
registered uses of dicamba are eligible for reregistration provided that the mitigation measures
are adopted on product labels.

       The risk assessments for dicamba are based on the best scientific data currently available
to the Agency and are adequate for regulatory decision making.

VI.    Appendices
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Labeling Changes Summary Table
In order to be eligible for reregistration, amend all product labels to incorporate the risk mitigation measures outlined in Section IV.
The following table describes how language on the labels should be amended.
Table 13: Summary of Labeling Changes for Dicamba
Description
For all Manufacturing
Use Products
One of these statements
may be added to a label
to allow reformulation
of the product for a
specific use or all
additional uses
supported by a
formulator or user
group
Environmental Hazards
Statements Required
by the RED and
Agency Label Policies
Amended Labeling Language
"Only for formulation into an herbicide for the following use(s) [small
grains, corn, sorghum, sugar cane, golf course and residential lawns, sod
farms, pastures, rangeland and rights of ways]."
"This product may be used to formulate products for specific use(s) not
listed on the MP label if the formulator, user group, or grower has
complied with U.S. EPA submission requirements regarding support of
such use(s)."
"This product may be used to formulate products for any additional
use(s) not listed on the MP label if the formulator, user group, or grower
has complied with U.S. EPA submission requirements regarding support
of suchuse(s)."
"Do not discharge effluent containing this product into lakes, streams,
ponds, estuaries, oceans, or other waters unless in accordance with the
requirements of a National Pollution Discharge Elimination System
(NPDES) permit and the permitting authority has been notified in writing
prior to discharge. Do not discharge effluent containing this product to
sewer systems without previously notifying the local sewage treatment
plant authority. For guidance contact your State Water Board or
Regional Office of the EPA."
Placement on Label
Directions for Use
Directions for Use
Precautionary Statements
End Use Products Intended for Occupational Use (WPS and Non WPS uses)
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PPE Requirements
Established by the
RED1
For Liquid, Wettable
Powder, Granulars and
Water Dispersible
Granular
Formulations
"Personal Protective Equipment (PPE)
Some materials that are chemical-resistant to this product are (registrant
inserts correct chemical-resistant material). If you want more options,
follow the instructions for category" [registrant inserts A,B,C,D,E,F,G,or
H\ on an EPA chemical-resistance category selection chart."

All mixers, loaders, and applicators and other handlers must wear :
< Long-sleeved shirt and long pants
< Shoes plus socks, and
< Chemical-resistant gloves (except for applicators using groundboom
equipment, pilots and flaggers)

"See engineering controls for additional requirements and exceptions."
Immediately following/below
Precautionary Statements: Hazards to
Humans and Domestic Animals
User Safety
Requirements
"Follow manufacturer's instructions for cleaning/maintaining PPE. If no
such instructions for washables exist, use detergent and hot water. Keep
and wash PPE separately from other laundry."
Precautionary Statements: Hazards to
Humans and Domestic Animals
immediately following the PPE
requirements
Engineering Controls
for Liquid, Wettable
Powder, Granulars and
Water Dispersible
Granular
Formulations
Pilots must use cockpits in a manner that meets the requirements listed in
the Worker Protection Standard (WPS) for agricultural pesticides (40
CFR 170.240(d)(4-6).
Precautionary Statements: Hazards to
Humans and Domestic Animals
(Immediately following PPE and User
Safety Requirements.)
User Safety
Recommendations
"USER SAFETY RECOMMENDATIONS"

"Users should wash hands before eating, drinking, chewing gum, using
tobacco, or using the toilet."

"Users should remove clothing/PPE immediately if pesticide gets inside.
Precautionary Statements under:
Hazards to Humans and Domestic
Animals immediately following
Engineering Controls

(Must be placed in a box.)
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                        Then wash thoroughly and put on clean clothing."

                        "Users should remove PPE immediately after handling this product.
                        Wash the outside of gloves before removing.  As soon as possible, wash
                        thoroughly and change into clean clothing."
Environmental Hazards
"Do not apply directly to water, or to areas where surface water is present
or to intertidal areas below the mean high water mark. Do not
contaminate water when disposing of equipment washwater or rinsate."
Precautionary Statements immediately
following the User Safety
Recommendations
Restricted-Entry
Interval for products
with directions for use
within scope of the
Worker Protection
Standard for
Agricultural Pesticides
(WPS)
"Do not enter or allow worker entry into treated areas during the
restricted entry interval (REI) of 24 hours."
Directions for Use, Under Agricultural
Use Requirements Box
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Early Entry Personal
Protective Equipment
for products with
directions for use
within the scope of the
WPS
For minimum early entry PPE use the following:
"PPE required for early entry to treated areas that is permitted under the
Worker Protection Standard and that involves contact with anything that
has been treated, such as plants, soil, or water, is:
* coveralls worn over short-sleeve shirt and short pants,
* chemical resistant footwear plus socks
* chemical-resistant gloves made of any waterproof material
* chemical-resistant headgear for overhead exposure.
* protective eyewear

"Notify workers of the application by warning them orally and by posting
warning signs at entrances to  treated area."
Direction for Use
Agricultural Use Requirements box
Entry Restrictions for
products having
occupational uses on
the label not subject to
the WPS
For products applied as sprays

"Do not enter or allow others to enter until sprays have dried."

For products applied dry

"Do not enter or allow others to enter until dusts have settled."
If no WPS use on the product label,
place the appropriate statement in the
Directions for Use Under General
Precautions and Restrictions. If the
product also contains WPS uses, then
create a Non-Agricultural Use
Requirements box as directed in PR
Notice 93-7 and place the appropriate
statement inside that box.
General Application
Restrictions
"Do not apply this product in a way that will contact workers or other
persons, either directly or through drift.  Only protected handlers may be
in the area during application."
Place in the Direction for Use directly
above the Agricultural Use Box.
Other Application
Restrictions (Risk
Labels must be amended to reflect the following maximum application
Directions for Use
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Mitigation)
rates and the maximum number of treatments per year:

Maximum single application rate: 1.0 Ib ai/acre and no more than 2
applications per year.
Spray Drift
"Do not apply this product in a way that will contact workers or other
persons, either directly or through drift."
Directions for Use
                                            End Use Products Intended for Residential Use
Environmental
Hazards
"Do not apply to water.  Do not contaminate water when disposing of
equipment washwaters or rinsate."
Precautionary Statements Immediately
Following the User Safety
Recommendations
Application
Restrictions
"Do not apply this product in a way that will contact any person, pet,
either directly or through drift. Keep people and pets out of the area
during application."
Directions for Use under General
Precautions and Restrictions
Entry Restrictions
For products applied as sprays:

"Do not allow people or pets to enter the treated area until sprays have
dried."

For products applied dried

"Do not allow people or pets to enter the treated area until dusts have
settled."
Directions for use under General
Precautions and Restrictions
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1 PPE that is established on the basis of Acute Toxicity of the end-use product must be compared to the active ingredient PPE in this document.
The more protective PPE must be placed in the product labeling. For guidance on which PPE is considered more protective, see PR Notice 93-7.
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