UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON,
D.C. 20460
OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION Methomyl (090301): Risk Mitigation Decision for Risks Due to Drinking Water Concerns Summary This document presents the mitigation measures that methomyl technical and end user registrants Chemtura Corporation, E.l. DuPont de Nemours and Company (DuPont), Glades Formulating Corporation, Rotam Limited, and Sinon Corporation, have voluntarily agreed
to implement

in order to mitigate estimated dietary risk due to drinking water exposure. To ensure timely implementation

of the changes
to several crops regarding number of applications and maximum seasonal rate, EPA
is taking steps to make sure that the new use restrictions appear on all methomyl product labels by the end of 2014. The mitigation measures will cancel the use of methomyl
on barley, oat, and rye and restrict its use on wheat to Idaho, Oregon, and Washington. For celery, head lettuce, and peppers the number of applications will be reduced by 20% and the seasonal maximum rate will be reduced by 12% to 20%

. For com, language will be added to labels that will change the timing of applications such that only two applications can occur prior to tassel push, at the 1-2 leaf stage, and applications will no longer be able to occur on bare soil. Additionally,
the number of applications
for leaf lettuce, field com, popcorn, and seed com will be reduced 25% to 50%. While Florida and California were the areas of greatest concern for risks to drinking water, the registrants have agreed to implement the mitigation nationwide. While the risk assessment phase of registration review for methomyl

is only just beginning, this effort to mitigate

a chemical's risks early in the registration review process

is consistent with the Agency's approach

to registration review. Where risks are identified early in the process and opportunities

for early mitigation exist, the Agency will pursue those opportunities

as they arise, rather than waiting for completion

of a chemical's registration review in order to mitigate risks. Background Methomyl

is anN-methyl carbamate insecticide currently registered for use on a wide variety of sites including field, vegetable, orchard crops, and on **~urf** (sod farms only). Methomyl is generally

a restricted use pesticide [based on percent active ingredient

(a.i

. )]. There are currently
no homeowner uses. However, certain low percentage
a.i. formulations
are not designated

as restricted use and can be used around livestock quarters, commercial premises, and refuse containers. Methomyl was first registered

in the United States in 1968. A Reregistration

1Eligibility Decision (RED) was completed

in 1998

1 • Methomyl

is the primary metabolite

of thiodicarb, which

is also an insecticide. Methomyl

is currently undergoing registration review, EPA's periodic reevaluation

of all registered pesticides

to ensure that they continue
to meet the statutory standard
of no unreasonable adverse effects. The risk assessment phase of registration review for methomyl begins in mid-2014 with the release for public comment
of the draft risk assessments anticipated in the summer of 2015. Results of the Agency's Dietary Risk Assessment The Agency's dietary risk assessment included drinking water exposure estimates that used the most refined regional percent cropped area (PCA) factors consistent with recommendations from the Scientific Advisory Panel's

2 peer review. This resulted
in a number of methomyl uses which caused the human health dietary assessment

to indicate potential risk of concern. The approach used for evaluating and characterizing
the drinking water exposure concerns for methomyl are consistent with the approach used during the mitigation

of oxamyl drinking water risks of concern.

3 This stands in contrast
to the assessment provided by DuPont

4 , which explored crop-by-crop
and region-by-region PCA factors. While DuPont's analysis looked at PCAs on a finer scale using the available data, their approach

is not currently
an Agency approved approach nor has their approach been informed by an SAP review, and thus, could not be used quantitatively

in the Agency's assessment. The Agency looked
at its drinking water simulations

in the context of recent methomyl usage data in an effort to further characterize
the risk. See Appendix

A for "MethomylSummary of Agency Drinking Water Assessment and Discussion
of Risk Management Options", which lays out the risk management analysis and options for resolution

. In general, methomyl's use, regardless
of crop, appears
to occur predominantly

in the southeast (primarily Florida and Georgia), the three west coast states (California, Washington,
and Oregon), the southwest (Texas and Arizona), and the northeast (New York, Pennsylvania,
and New Jersey)

. More specifically, geographically

on a state-by-state basis, methomyl's use in Florida and California significantly exceeds
its use in any other state. In fact, methomyl's use in those two states exceeds
its use in all the other states combined. The usage data also suggested that the application rate, retreatment intervals, and number of applications could be reduced below that on currently registered product labels in order to reduce drinking water exposure.

In addition, the usage data indicated that methomyl has very 1 Available

at http://www.epa.gov/oppsrrd l/REDs/0028red.pdf. 2 U.S. EPA (I 999). Scientific Advisory Panel Report- Sets of Scientific Issues Being Considered

by the Environmental Protection Agency Regarding: Session III- Use of Watershed-derived Percent Crop Areas as a Refinement Tool in FQPA Drinking Water Exposure Assessments

for Tolerance Reassessment. Available

at http:/ /www.epa. gov/scipo

I y/sap/meetings/ 1999/ma y/final.pdf

. 3 U

. S . EPA (2011) Oxamyl Mitigation

of Dietary (Drinking Water) Risks of Concern for Certain Use Sites

. Available

at http

: //www

. regulations

. gov/#!documentDetail

; D=EPA-HQ-OPP-20

I 0-0028-0021

. 4 N. Snyder,
A. Klemens,

K. Wright,

S . Zelonis

. Sponsored
by E
. I. duPont de Nemours and Company. Tier
2 Dietary and Drinking Water Risk Assessment
for Methomyl Under Current Use Guidance

. June 7, 2012. MRID 48859101.

2littleuseonseveralmajorrowcrops.Removalofthesecropsfromthemethomyllabelwillreducetheestimateddrinkingwaterconcentrationsinthenationwideriskassessment,andcouldopenuproomintheriskcupformethomylandthen-methylcarbamatecurpulativeassessment.RegistrantAgreed-toMitigationBasedupontheregistrantagreedtomitigation,identifiedinTables1and2below,whichcancelssomeusesandreducesthenumberofapplicationsandtheseasonalmaximumrateforsomecrops,drinkingwaterconcernshavebeensufficientlymitigatedatthistime.WhileFloridaandCaliforniawereidentifiedastheareaswhereweweremostconcernedaboutdrinkingwaterriskbecausemostofthemethomyluseoccursinthosetwostates,theregistrantshaveagreedtoimplementthemitigationnationwide.SeeAppendixBfortheAgency'scompleteanalysissupportingthesufficiencyofthemitigationtoaddressdrinkingwatercmwemsinFloridaandCalifornia.Tbl1 Ad tMit'fMtha e..gree-oIgaIOnore I R Comy1onowropsLabeledCropMitigationBarleyCancelUseOatsCancelUseRyeCancelUseWheatCancelUseExceptinID,OR,andWANumberofApplicationsCurrent*ProposedCom,Field105Com,Pop105Com,Seed105Timingofapplications:DonotmakemorethantwoCom,Sweet,applicationstocompriortotasselpush.Make1Field,Pop,andapplicationwhencomisat1-2leafstageforcontrolSeedofearlyseasonpests;makeasecondapplication,ifneeded,5-7dayslater.Tbl2A a e.lgreedtMiffMth- 0IgaIOnoreI VblomylonegetaesCropNumberofApplicationsSeasonalMaximumRateObsa.iJAcre)Current*ProposedCurrent*ProposedCelery1087.26.3HeadLettuce15127.26.3LeafLettuce863.63.6Peppers1084.53.6*Currentlyonlabels.ConclusionThisdocumentpresentsthemitigationmeasuresbeingtakenvoluntarilybyregistrantsinordertomitigateestimateddietaryriskduetodrinkingwaterexposurefrommethomyl.TheAgencybelievesthatthesereductionsinthemaximumseasonallabelratesformethomyl3mitigate our concerns about dietary risk due to drinking water exposure from methomyl. This and all other documents related
to methomyl registration review are located
at http://www.regulations.gov

under docket number EPA-OPP-2010-0751. **~~** Richard
P. Keigwin,
Jr. Director Pesticide Re-evaluation Division

4APPENDIXAUNITEDSTATESENVIRONMENTALPROTECTIONAGENCYWASHINGTON,D.C.20460SENTVIAEMAILOFFICEOFCHEMICALSAFETYANDPOLLUTIONPREVENTIONTo:PatriciaG.Devine,ProductRegistrationManagerDuPontCropProtectionRe:Methomyl-SummaryofAgencyDrinkingWaterAssessmentandDiscussionofRiskManagementOptionsDate:March20,2013ThisdocumenthighlightsresultsofEPA'sdietaryriskassessmentformethomylasitrelatestospecificcropsandareasofthecountry.ItisourefforttonotethedifferencesbetweenDuPont'sdrinkingwaterassessmentandtheAgency'sassessment becausethesedifferencesresultinanumberofdietaryrisklevels-of-concernexceedancesinEPA'sassessment.Atthesametime,fromariskmanagementperspective,possibleoptionsformitigatingtherisksarediscussed.ResultsoftheAgency'sDietaryRiskAssessmentOurriskassessorsevaluatedthepotentialdietaryriskofmethomylusingPRZMIEXAMStosimulatedrinkingwaterexposure,andDEEMtocombineexposurethroughresiduesonfoodwithdrinkingwaterexposure.TheteamranPRZMIEXAMSsimulationsformostmethomylcropsusingtherepresentativestandardscenarioforanationalassessment,aswellasanumberofadditionalregionalassessments.Inaddition,drinkingwaterexposurewascalculatedforanumberofscenariosusingthelowestregionalpercentcroptreated(PCA)forregionseastoftheeasterndivideandwestofthewesterndivide(0.13),andusingthelowestregionalPCAformidcontinentregions(0.35).Thesewereconsideredlower-boundvaluestocomparewiththerepresentativescenariosandPCAsshowninTable1,below.EPA'sapproachtothemethomyldrinkingwaterassessmentusesthesameinputs(rates,numberofapplicationsandretreatmentintervals)asDuPontusedinitsassessment(June7,2012),butdidnotcalculatecropandwatershed-specificPCAfactors.EPA'suseofPCAsinitsdrinkingwaterassessmentisconsistentwiththeapproachdiscussedinthe1999ScientificAdvisory5Panel's report

5 on this subject. The PCAs shown in the table below are regional PCAs associated with the standard scenarios chosen
to represent nationwide methomyl use allowed by its labels. Due to the difference

in how the regional PCAs are utilized
in EPA's assessment,

a number of crops exceed the level of concern for dietary risk although they passed
in DuPont's assessment. As a rule of thumb, estimated drinking water concentrations above 10 ppb resulted
in failure of the DEEM aggregate simulation.
Of the example crops listed in Table

1, only apples and potatoes passed using the PCAs presented. Table

1

Representative Scenario States with highest methomyl use, descending

Peak ppb& Peak ppb & Crop
order Scenario* PCAGround PCAAerlal Lettuce
CA,AZ

CA lettuce STD 99.31 (0.6i)

-- Onion

OR, WA, CA, 10, NY, TX, CO GAOnion WirrigSTD 39.80 (0.41) 38.89 (0.41) FL, GA, CA, NY, PA, NJ, OH,

127.54 Sweet Corn MI,IL,WI

KS Corn STD (0.87) 124.93 (0.87) Tomatoes

CA, FL

FL tomato STD 37.50 (0.41) 36.82
(0

. 41) Potatoes WA,CA,OR,NY,PA,NC

ME potato STD 3.95 (0.13) 4.06 (0.13) Peppers

FL, AZ, CA, NJ, GA, NC, OH
FL pepper STD 50.79 (0.41) 49.22 (0.41) FL, NC, NY, TX, CA, CO, AR, Cabbage

Ml Brownsville

TX 74.24 (0.69)

-- Apples

VA, Ml, WV, PA, NY, OH, NC PA apples STD V2 8.38 (0.34) 8.52 (0.34) ground TX alfalfaOP; Alfalfa
CA,CO

aerial NC alfalfa OP 81.08
(0

. 69) 11.81 (0.41) Beans (Snap, Bush, Pole, String)

FL, TX, GA, CA, PA, WI
Ml beansSTD
72.28 (0.81) 71.15 (0.81) Peaches

NJ, AL, PA, Ml, CA

GA Peaches STD 11.23 (0.41) 11.62 (0.41) Celery
CA,MI

CA cole crop RLF v2 86.68 (0.61)

-- *Where there

is a ground and aerial peak ppb and PCA, unless indicated, the scenario

is for both ground and aerial The consideration

of default regional PCAs represents the extent of refinement that could be done for the drinking water exposure assessment, given the wide variety of crops on methomyl labels and the fact that there are no geographical limitations
for the use of methomyl. However, we have taken

a closer look at where methomyl appears
to actually be used (geographically
and crop specific) based upon our use and usage information from the most recent available 5-year period. Upon this closer evaluation

of methomyl'

s apparent geographical
use and predominant crop specific use, there may be options for moving forward
to mitigate the issues driving the failure of certain crops. 5 U

. S. EPA (1999). Scientific Advisory Panel Report- Sets of Scientific Issues Being Considered

by the Environmental Protection Agency Regarding: Session III- Use of Watershed-derived Percent Crop Areas as a Refinement Tool in FQPA Drinking Water Exposure Assessments
for Tolerance Reassessment. Available

at http://www .epa

. gov/scipo

I y/sap/meetings/ 1999/may/final

. pdf

.

6In general, methomyl's use, regardless

of crop, appears
to occur predominantly

in the southeast (primarily Florida and Georgia), the three west coast states (California, Washington,
and Oregon), the southwest (Texas and Arizona), and the northeast (New York, Pennsylvania,
and New Jersey). MQre specifically, geographically

on a state-by-state basis, methomyl's use in California and Florida significantly exceeds
its use in any other state. In fact, methomyl'

s use in those two states exceeds
its use in all the other states combined. In addition, the use of methomyl appears
to be insignificant
for major crops which account for much of the area in default PCA calculations. For instance, the average percent crop treated for spring and winter wheat for the last five years has been 0.0, according

to our analysis. The same is true for both soybeans and field com. Use records suggest that what use has occurred has not been in the same regions where the major methomyl use occurred on sweet com and vegetables. Consideration

of drinking water exposure

in the **co~J.text** of methomyl usage data Given the usage data described above, we undertook

a "what-if' assessment along the lines of that performed
for the oxamyl drinking water assessment, exploring which use/region combinations might pose the greatest risk of drinking water contamination

. In this risk management exercise we looked
at modeling runs that best approximated
the areas of major use of methomyl, and applied combined PCA factors for crops on which methomyl has been used, most often those for vegetables and com (to account for sweet com). In the cases for which

a nearby scenario was not available, we took the results of the national standard scenario and applied the appropriate PCAs for the major use region being evaluated

. This exercise does not by itself change the risk assessment nor the status of the methomyl "risk cup."
It does, however, clarify which uses most require mitigation for protection

of drinking water, and where. Table

2 indicates which uses failed both with the national representative standard scenario and regional default PCAs, and under the "what-if' scenarios using more representative scenarios and smaller PCA factors.
In short, the main drinking water concerns which require resolution are the use of methomyl
on sweet com in Florida and Georgia, the use on vegetables (especially lettuce and brassicas)

in California, and the use on onions
in New York. The region-specific PCAs include EPA's recently released regional PCA adjustment factors

6 for vegetables along with regional PCAs for other crops for which there was reported methomyl use between 2007 and 2011. Table

2

PCARegion Crop

States Scenario Specific Sweet Corn

FL, GA

FL sweet corn OP 0.16, 0.30 Lettuce (and spinach)

CA

CA lettuce STD
>0.29 Peppers

CA

FL pepper STD
>0.29 6 Available

at http://www

. epa. gov/oppefed 1/models/water/pca adjustment dwa.html#

3 regional group

.

7Cabbage

CA

CA cole crop RLF v2 >0.29 Celery

CA

CA cole crop RLF v2 >0.29 Onions

NY GAOnion WirrigSTD

Up to 0.41 Options for Moving Forward Sweet corn in Florida and Georgia Methomyl's major uses in Florida appear to be on vegetables and sweet com, with no reported use on wheat, soybeans, citrus, or field com. A Florida sweet com scenario was run with the default regional PCA of 0.41, which resulted
in residues that caused the human health aggregate assessment

to fail. In looking

at the regional vegetable PCA, the maximum

is 0.07 and the maximum
for com is 0.09. If one were to conservatively combine these two maximum PCA factors, recognizing that the com value may in part represent land cropped
to field com, the resulting drinking water concentration

is near to that which would result in an acceptable dietary risk. The major use of methomyl

in Georgia

is on sweet com, with lesser amounts used on vegetables and cotton. According

to 2007 Census of Agriculture maps, major cotton, vegetable and sweet com growing areas coincide
in the southwestern portion of the state. When considered with the additional reported use on watermelons and cantaloupe,
the default regional PCA could be as high as 0.30, but in any case would be higher than that needed
to result in acceptable dietary risk. Methomyl usage data for sweet com suggest that actual usage
is significantly less than modeled by both the Agency and DuPont. Modeled concentrations

for sweet com were derived using an application rate of 0.45lb/A applied
14 times with

a 1-day application interval. Usage data indicate that the average application rate in Florida and Georgia was 0.3 lb/ A, with an average of about

9 applications

a year. It appears that there
is room to reduce the rate, number of applications and perhaps application interval
to reduce the potential for risk
to drinking water. Vegetables

in California Lettuce: Lettuce would fail using the California lettuce scenario and the regional vegetable PCA of 0.29 alone, which does not account for reported use on sweet com, cotton and citrus crops. The lettuce scenario was also used to represent use on spinach, which therefore also would fail in this "what-if' exercise. Methomyl usage data for lettuce suggest that actual usage
is significantly less than simulated by both the Agency and DuPont. Modeled concentrations

for lettuce were derived using an application rate of 0.9lb/A applied

6 times

a year with

a 2-day application interval. Usage data indicate that the average application rate in California was 0.8lb/A, with an average of about

2 applications

a year.
It appears that there
is room to reduce the number of applications and perhaps the interval
to reduce the potential for risk to drinking water.

8Peppers: Because there
is not
a standard scenario for California peppers, we considered the Florida pepper scenario deemed representative

by EPA for this exercise. DEEM calculated exposure
of 103% of the aPad for a PCA of0.35 (one of the bounding assumptions explored

as described above). Given the regional PCA of 0.29 for vegetables, and the use of methomyl
on sweet com, cotton and citrus in the same region of California, one cannot dismiss risk

. from pepp.ers
in this "what-if' exercise. Methomyl usage data for peppers suggest that actual usage
is significantly less than modeled by both the Agency and DuPont. Modeled concentrations were derived using an application rate for peppers of 0.9lb/A applied

5 times

a year with

a 5-day application interval. Usage data indicate that the average application rate for peppers
in California was 0.7lb/A, with an average of about 2 applications

a year.
It appears that there
is room to reduce the rate, number of applications and perhaps application interval
to reduce the potential for risk to drinking water. Cabbage:

A California standard scenario was available for cabbage, and it resulted
in higher peak concentrations than the scenario chosen
as representative

of the rest of the country. DEEM calculated exposure
of 102% of the aPad for a lower-bound PCA of0.13. California cabbage would therefore still fail with

a regional vegetable PCA of 0.29, and more so if one considered use of sweet com, cotton and citrus crops in the PCA. Methomyl usage data for cabbage suggest that actual usage
is significantly less than modeled by both the Agency and DuPont. Modeled concentrations were derived using an application rate for cabbage
of 0.9lb/A applied

8 times

a year with

a 2-day application interval. Usage data indicate that the average application rate in California for cabbage was 0.7lb/A, with an average of about 2 applications

a year. It appears that there
is room to reduce the rate, number of applications and perhaps application interval
to reduce the potential for risk to drinking water. Celery: Use on celery was simulated using the same standard scenario

as for cabbage, but with

a different application interval. DEEM calculated exposure
of 97% of the aPad for a lower-bound PCA of 0.13, and exceedance

of the aPad from water alone using

a PCA of 0.35. Given the regional PCA of 0.29 for vegetables, and the use of methomyl
on sweet com, cotton and citrus in the same region of California, one cannot dismiss risk from celery in this "what-if' exercise. Methomyl usage data for celery suggest that actual usage
is significantly less than modeled by both the Agency and DuPont. Modeled concentrations were derived using an application rate for celery of 0.9lb/A applied

8 times

a year with

a 5-day application interval. Usage data indicate that the average application rate for celery in California was 0.7lb/A, with an average of about

2 applications

a year.
It appears that there
is room to reduce the rate, number of applications and perhaps application interval
to reduce the potential for risk to drinking water. Onions
in New York Usage data indicate that the second most important state for methomyl use on onions

is New York. Onions and sweet com seem to be grown in the same area, much of it in the Great Lakes region, and methomyl use on apples was reported for New York, as well. Drinking water concentrations derived using the representative standard scenario caused the dietary assessment

9to fail whether considering

a PCA of 0.41 or 0.35. Whether the vegetable and corn PCAs for Region

2 or Region

4 are considered
for New York, one cannot dismiss the potential for dietary risk with this "what-if' scenario. However, while the usage data for onions indicates that the 0.9 lb/ A rate modeled
in the modeling

is the actual average use rate for New York, the average

of 3 applications per year is half the 6 applications simulated

in the modeling. Do low-benefit uses need to be retained? As described above,

a risk management exercise considering PCA factors without the inclusion of major row crops was only possible because our usage data indicate that methomyl

is not used much on these crops. The average percent crop treated for wheat, soybeans and corn all were calculated

to be 0.0 for the most recent 5-year period reviewed, suggesting that there
is little benefit associated with these methomyl registrations. However, these crops do contribute greatly to the national and regional default PCAs used for the human health dietary risk assessment. We suggest that DuPont consider removing these registered uses from methomyl.labels

to provide room in the "risk cup" for the existing high-use crops, and perhaps then-methyl carbamate cumulative assessment. Conclusion The Agency's dietary risk assessment included drinking water exposure estimates that used the most refined regional PCA factors that are permissible
by the recommendations provided through SAP peer review. This results in a number of methomyl uses which cause the human health dietary assessment

to indicate potential risk of concern. This stands in contrast
to the assessment provided by DuPont, which explored crop-by-crop and region-by-region PCA factors that are not consistent with SAP recommendations. The Agency looked
at its drinking water simulations

in the context of recent methomyl usage data as a risk management exercise. Identification

of where methomyl was used most, and on which crops, allowed
us to perform

a "what-if' evaluation consistent

with that done for oxamyl. Through this we identified which crop-location combinations would still result in estimated dietary risk due to drinking water exposure. The usage data used in this exercise also suggests that the application rate, retreatment intervals, and number of applications
for these crops could be reduced below that modeled

in order to reduce drinking water exposure.

In addition, the usage data indicate that methomyl has very little use on several major row crops. Removal
of these crops from the methomyllabel would go a long way in reducing the estimated drinking water concentrations

in the nationwide risk assessment, and could open space in the risk cup for methomyl and the n-methyl carbamate cumulative assessment.

10APPENDIXB Analysis Indicating Sufficiency

of Mitigation

to Address Drinking Water Risk Concerns

in Florida and California Florida The main concern for possible methomyl

in drinking water in Florida

is associated with use on vegetables. Although

it can be used on orchard crops, usage data available

to the Agency does not indicate use in Florida. In its response

to the Agency's request, DuPont provided information
on the co-occurrence

of other potential methomyl crops in areas of Florida where vegetables are grown. These maps indicate that sweet com is grown more in Georgia and up the southeastern seaboard than in Florida. USDA Agricultural Census maps from 2007 indicate that vegetables and sweet com are both grown in Palm Beach County (most likely the Everglades Agricultural Area. However,

as indicated by the Palm Beach County Water Utilities Department's 2012 report, "Palm Beach County Water Utilities Department's drinking water
is drawn from wells extending approximately
150 feet underground." Furthermore,
the City of West Palm Beach,
in their 2012 report, indicated that "the City of West Palm Beach gets its water from rainfall captured and stored in a part of the Everglades Ecosystem known
as the Grassy Waters Preserve. This system feeds and sustains Lake Mangonia and Clear Lake. In past years the City has, at times, been able to supplement

its water supply from Lake Okeechobee."

It states further **th~t** "in 2012 the Florida Department

of Environmental Protection performed

a Source Water Assessment

on our system. These assessments were conducted

to provide information
on any potential sources of contamination

in the vicinity of our wells and source water intake.
A search of the data sources indicated
no potential sources of contamination within the assessment area for our system." The DuPont response also provided information

on potential co-occurrence

of vegetables with alfalfa and pasture grass. This memo did not indicate co-occurrence with alfalfa, which

is consistent with usage data available
to the Agency. There
is co-occurrence

of pastureland

in watersheds

in which vegetables
are grown, but the predominant pasture grass grown in Florida

is bahia grass, and methomyl

is only labeled for use on bermudagrass. The Agency believes that, to the extent that surface water
is used as a drinking water source in Florida, that potential drinking water exposure

to methomyl

is best characterized

by the use on vegetables. The proposed reduction

in the maximum label rates for methomyl use on vegetables is sufficient

to mitigate concerns for drinking water in Florida for methomyl itself. The potential cumulative exposure

to methomyl and other n-methyl carbamates

is currently being reassessed. California When the Agency first identified use on vegetables

in California and Florida
as the most likely causes of significant drinking water exposure

to methomyl,

it was based on available methomyl

11usage data and the use of a 0.29 percent cropped area (PCA) factor for vegetables

in California. DuPont responded
by pointing out that the most appropriate PCA for vegetables

in Region
18 (which includes California)

is 0.10, and the Agency agreed. DuPont calculated that, when this PCA was used and DEEM run considering "eating occasion exposure," the use on vegetables resulted
in acceptable aggregate exposure. While the PCA for vegetables

is 0.10,
it is important

to consider other crops on which methomyl is registered. The orchard crop group could be important

in California, except that 1) the PCA for orchards includes use on grapes, for which methomyl

is no longer registered, and 2) the assessment
for the various orchard crops passed the dietary screen. In addition, available data indicate that
a small amount of methomyl

is used on orchard crops in California, and only on a small percentage

of the crops grown. Use on cotton also is much less significant than on vegetables, with

a very small percentage

of the crop in California treated. The Agency acknowledged
that the corrected PCA for vegetables improved the picture for drinking water exposure

to methomyl

in California, but requested additional information

on potential co-occurrence with areas in which alfalfa

is grown, even though the assessment
for alfalfa itself passed the dietary screen. DuPont provided information

on the co-occurrence

of alfalfa and vegetables

in California watersheds, which indicated that the percent cropped
to alfalfa in the great majority
of watersheds

in California was below 5%, with

a maximum
.of 9.6%. The highest PCAs for alfalfa do not correspond with the maximum PCAs for vegetables. Furthermore, while there
is a significant amount of methomyl used on alfalfa
in California,
the percent of the crop treated

is only around 10%. Therefore, while DuPont indicated that the dietary assessment
for vegetables would pass if one applies the vegetable PCA of 0.10 to the drinking water exposure values for vegetables, the PCA should perhaps be adjusted slightly higher for use on alfalfa

. However,

it is important

to acknowledge that the screening drinking water exposure values were derived using the highest application rates, maximum number of applications and shortest retreatment intervals allowed on the labels. Usage data for California indicate that less methomyl

is applied
in practice, and the percent of each crop treated

is significantly less than the 100% assumed

in the screen. The proposed reduction

in the maximum label rates for methomyl use on vegetables

is sufficient

to mitigate concerns for drinking water in California for methomyl itself. The potential cumulative exposure

to methomyl and other n-methyl carbamates

is currently being reassessed.

12