Page | 2 field crops. There are no re sidential uses for oxamyl, and it is a member of the N -methyl carbamate (NMC) class of chemicals that shar e a common mechanism of toxicity and inhibit acetylcholinesterase.

The Interim Reregistration Eligibility Decision (IRED) for Oxamyl was completed in October 2000, and the Reregistration Eligibility Decision (RED) for Oxamyl 1 was finalized in September 2007 upon completion of the Revised N-Methyl Carbamate Cumulative Risk

Assessment. To evaluate dietary and drinking water exposures, the oxamyl RED used a combination of modeling, with the drinking wate r and dietary models typical of that time 2 , and available surface and ground water monitoring data. The oxamyl RED determined that estimated environmental concentrations of oxamyl residues in surface and ground water were less than the acute drinking water level of concern (DWL OC) for the general population. Estimated concentrations of oxamyl residue s in ground water were found to be potentially greater than the DWLOC for children 1 to 6 years of age, and of c oncern to EPA. To mitigate this potential risk and reduce dietary exposures for children in the ages 1 to 6 population subgroup, the registrant agreed to reduce the application rates for cotton and various othe r crops. Furthermore, the RED concluded that the food plus dr inking water dietary assessment used conservative underlying assumptions (i.e., not accounting fo r the reversibility of cholineste rase inhibition or more refined food consumption patterns) which resu lted in an overestimate of risk.

The September 2007 Revised N-Methyl Carbamate Cumulative Risk Assessment evaluated the effects of oxamyl together with all other NMC pesticides . The toxicological endpoints and modeling parameters for the cumulativ e assessment were diffe rent from those of

the individual chemical risk assessments to prevent the compounding of conservative assumptions. For drinking water, the cumulative risk assessment relies on typical application rates and considers percent crop treated for the va rious chemicals that can be co-located in a watershed. No food or drinking water risk conc erns were identified for oxamyl in the NMC

cumulative assessment.

In May 2007, DuPont Crop Protection (DuPont), the technical registrant for oxamyl, submitted a petition (PP6F7136) to EPA to estab lish a tolerance for the use of oxamyl on sugar beets, and in September 2007, they submitted another petition (PP7F7242) to establish a tolerance on wheat. In 2008, EPA received a pro posed label amendment from DuPont to expand several existing uses of oxamyl. The above ne w use requests triggered the need for new risk assessments to determine if the requested actions would pose an unreasonable adverse effect to

human health or the environment. The new assessments incorporated changes in methodology that had occurred since the previous assessmen t was completed for the RED. The primary change to the modeling was that instead of comparing a drinking water point estimate (the DWLOC) to estimated drinking water exposures , a 30-year distribution of drinking water exposure values was incorporated directly into the DEEM-FCID 3 model for dietary exposures.

1 The Oxamyl RED can be accessed at: http://www.epa.gov/pesticides/rereg istration/REDs/oxamyl_red.pdf

2 Pesticide Root Zone Model – Exposure Analysis Modeling System (PRZM-EXAMS) and Dietary Exposure

Evaluate Model (DEEM)

3 Dietary Exposure Evaluation Model – Food Consumption Intake Database, version 2.03Page | 3 DEEM-FCID modeling currently includes exposures from food plus drinking water and accounts for the reversibility of acetyl cho linesterase inhibition caused by oxamyl 4

.

Several rounds of drinking water and dietary risk assessm ents for approximately 20 use

sites were conducted from 2009 to 2011 with increasi ng levels of refinement to evaluate the new use requests and the currently la beled uses of oxamyl. The early risk assessments identified several existing use sites where modeling refinement s and/or mitigation measures were needed to

address risk estimates above EPA’s level of c oncern. In December 2009, DuPont withdrew all of the new and expanded use requests until risk con cerns identified with existing labeled uses of oxamyl were resolved. In October 2010, DuP ont submitted a mitigation proposal to EPA for nine existing use sites.

DuPont’s proposed mitigation, along with the Agency’s refined drinking water modeling

and better characterization of dr inking water exposure, led EPA to conclude that all dietary (food plus drinking water) risks of concern have been adequately addressed. Modeling conducted for all use site scenarios and refinements is explai ned in Section III of this document. Because exposure from food alone occupies only 13% of the acute dietary risk cup (i.e., aPAD) for infants and 16% for children ages 1 to 2, re finements focused on the drinking water exposure

assessment.

A chronic dietary assessment is not requi red for oxamyl because, as is typical for N

methyl carbamate pesticides, reactivation of the enzyme, and therefore, of acetyl cholinesterase activity, occurs within a period of hours. Therefor e, acute inhibition of the acetyl cholinesterase enzyme is the exposure duration of concern. Further, because oxamyl is a restricted use pesticide and has no homeowner uses or other residential exposures, the aggregate assessment consists of food and drinking water exposures only.

Registration review is EPA’s program to peri odically reevaluate pes ticides to make sure that as the ability to assess risk evolves and as policies and practices change, products in the marketplace can continue to be used safely. The registration review pr ocess for oxamyl startedin September 2010 when the initial docket was opened for public comment (EPA-HQ-OPP2010-0028) and coincided with the ongoing oxamyl re gistration actions. The Preliminary Work Plan (September 2010) and Final Work Plan (F ebruary 2011) for the re gistration review of oxamyl both stated that EPA was in the process of working with DuPont to resolve concerns with some existing uses. Although new human health and ecological risk assessments are planned as part of the registra tion review process, they are not expected to be completed until Spring 2015. Due to the length of time before the registration review risk assessments and regulatory decision, EPA determined it was appropria te to resolve the known oxamyl dietary risk

concerns on an accelerated timeline.

4 The dietary modeling DEEM-FCID results were adjust ed to obtain “eating occasions” results using a SAS

algorithm to find the peak cholinesterase inhibition / exposure level in a day by accounting for the rise in exposure immediately upon eating and decay of the exposure to half its value after 150 minutes from ingestion.Page | 4 

### III. RESULTS OF REFINED DIET ARY (FOOD PLUS WATER)

MODELING AND PROPOSED MITI GATION FOR ALL EXISTING USE SITES, EXCLUDIN G TROPICAL CROPS

Results of the Agency’s refined dietary (food plus water) modeling are presented below in three groups: Group 1 use sites did not exceed EP A’s level of concern at the maximum labeled application rates and did not require mitigation; Group 2 use sites did not exceed EPA’s level of concern with mitigated use patterns (e.g., lowe r application rates); Gr oup 3 use sites with mitigated use patterns resulted in aPADs greater than 100% for infants only. However, as discussed later in this document, EPA believes that its analyses likely overestimate oxamyl exposures and therefore risks, a nd that actual oxamyl exposures for the Group 3 use sites will be below the level of concern for infants and children ages 1 to 2.

For additional details regarding the dri nking water and dietary modeling parameters and methodologies, please reference the following support documents located in the oxamyl registration review doc ket (EPA-HQ-OPP-2010-0028):

- Oxamyl: Acute Aggregate (Food and Drinking Water) Dietary Exposure and Risk Assessments for the Currently Registered Uses And Drinki ng Water Residue Distribu tions Resulting From Maximum and/or Reported Rates on Banana, Carro t, Celery, Cotton, Eggplant, Ginger, Peanut, Pear, Pineapple, Sweet Potato, Tobacco, and Yam . M. Sahafeyan. July 15, 2010.

- Update to Drinking Water Exposure Asse ssments for Current Uses of Oxamyl . G. Orrick. June 15, 2010.

a. GROUP 1 USE SITES

The use sites in Table 1 were below EPA’s level of concern at the maximum labeled application rates using the Envir onmental Fate and Effects Divisi on’s (EFED) standard Tier II drinking water modeling approach. These use sites did not require mitigation by the registrant

for EPA to conclude that continued use would be “safe.” Use patterns a nd application rates as currently labeled on oxamyl products are acceptable.

Table 1. Results of Oxamyl Acute Aggregate Dietary Risk Assessment at the 99.9 th Percentile of Exposure Distribution for Infants and Children 1 – 2 Years Old for Existing Labeled Use Sites at Maximum Application Rates.

Commodity %aPAD with Eating Occasions 5

Infants | Children 1 – 2 Worst-case Drinking Water HUC-2 Region 6 Percent Cropped Area (PCA)

Apple 34 21 n/a 7 (national default) 87

5 Data source for %aPAD: Oxamyl Acute Aggregate (Food and Drin king Water) Dietary Exposure and Risk

Assessments for the Currently-Registered Uses And Dr inking Water Residue Distributions Resulting From Maximum and/or Reported Rates on Banana, Carrot, Celery, Cotton, Eggplant, Ginger, Peanut, Pear, Pineapple, Sweet Potato, Tobacco, and Yam. M. Sahafeyan. July 15, 2010. DP Barcode 378341. (pgs. 14-15).

6 Data source for drinking water modeling: Update to Drinking Water Exposure Assessment for Current Uses of

Oxamyl. G. Orrick. June 15, 2010. DP Barcode 378338.Page | 5 Commodity %aPAD with Eating Occasions 5

Infants | Children 1 – 2 Worst-case Drinking Water HUC-2 Region 6 Percent Cropped Area (PCA)

Citrus 75 37 Region 3 8 38

Mint 19 18 n/a 7 (national default) 87 Onion 78 41 Region 12 8 67

Peanut 82 45 n/a 7 (national default) 87

Pear 42 25 n/a 7 (national default) 87 Sweet potato 71 39 n/a 7 (national default) 87

Tobacco 19 17 n/a 7 (national default) 87

b. GROUP 2 USE SITES

The use sites listed in Table 2 resulted in di etary risks of concern (i.e., aPADs greater than 100%) when modeled at the maximum current labeled rates using the standard Tier II drinking water modeling approach. DuPont s ubmitted a mitigation proposal to alter the use patterns for this group, which included lowering annual maximum application rates for certain states, reducing the number of applications per ye ar, and requiring a specific soil incorporation depth. The proposed mitigation measures are expl ained in further detail following Table 2. As a result of proposed mitigation, aPADs for the use s ites listed in Table 2 are below EPA’s level of

concern.

Table 2. Results of Oxamyl Acute Aggregate Dietary Risk Assessment at the 99.9 th Percentile of Exposure Distribution for Infants and Children 1 – 2 Years Old for Existing Labeled Use Sites at DuPont’s Proposed Mitigated Application Rates.

Commodity %aPAD with Eating Occasions Worst-case Drinking Water HUC-2 Region 9 Percent Cropped Area (PCA) Infants Children 1 – 2

Cotton 80 44 Region 11 80

Cucurbits 10 85 43 Region 12 67 Non-bearing fruit 74 39 Region 3 38 Peppers 72 38 Region 8 85

DuPont proposed changes to existing labe led use sites on a regional basis depending on the regional areas of con cern. EFED’s June 15, 2010 “Update to Drinking Water Exposure Assessments for Current Uses of Oxamyl” calculated 1-in-10-year p eak estimated drinking water concentrations (EDWCs) for each crop for each HUC-2 region where that crop is grown and

7 National level modeling c onducted for this use site.

8 There are eighteen HUC-2 watershed basins within the contiguous United States. Where estimated drinking water

concentrations were high for a national, screening-leve l assessment using a default PCA of 87%, the drinking water modeling was refined to a regional basis using regional PCA factors. The HUC-2 region listed in the table represents the worst-case scenar io which is assumed to be protective of all other regions.

9 The HUC-2 region listed in the table represents the wors t-case scenario which is assumed to be protective of all

other regions.

10 Oxamyl is labeled for use on the following cucurb it crops only: cucumber, cantaloupe, honeydew melon,

watermelon, squash, and pumpkin.Page | 6 labeled for use. Regions were identified as pot entially of concern if the EDWC exceeded the threshold concentration of 80 μg/L. Therefor e, DuPont’s proposed mitigation was targeted towards the HUC-2 regions identified to have 1-in-10 year peak EDWCs > 80 μg/L. Proposed mitigations for Group 2 use sites are listed below.

i. General Label Statement proposed by DuPont:

As part of its mitigation proposal, DuPont proposed to add the following general label statement to specify soil incorporation to a par ticular depth for all soil applications, including infurrow and shank applications. This proposed add itional language would apply to directions for use for all oxamyl applications and would allo w EPA to accurately specify a soil incorporation depth in the PRZM-EXAMS model.

“All applications to the soil must be inco rporated immediately after application to a depth of at least 2 inches by mechanical means or by water. For best results, Vydate® should be placed in the root zone of the plant. If irrigation is used to water in the application, use sufficient wate r to move the applie d Vydate® at least 2 inches deep in the soil. However, do not apply irrigation water such that the

water moves off the field.”

ii. Mitigation proposed by DuPont for cotton:

 In AR, KS, LA, MS (west of I-55), OK, and TX, apply up to 0.5 pounds active ingredient per acre (lbs a.i./A) of oxamyl per individual application with a maximum of 4 foliar applications.

 The minimum retreatment interval between all applications is 7 days.

 Do not apply more than 1 gallon of produc t (2 lbs a.i. of oxamyl) per acre per

season.

 For all other states, application rates stay as specified on the current product label.

iii. Mitigation proposed by DuPont for cucurbits:

 In AL, FL, GA, MS, NC, SC, and TX (excep t Rio Grande Valley), apply up to 1 lb

a.i./A oxamyl pre-plant, at-plant, or transplant. Foliar, drip and/or soil injection applications can also be made. Apply up to 1 lb a.i./A oxamyl with a maximum of

3 applications. The minimum retreatment interval between all applications is 7 days.

 In AL, FL, GA, MS, NC, SC, and TX (excep t Rio Grande Valley), up to 2 lbs a.i./A oxamyl pre-plant, at-plant or transplant may be applied. However, if more than 1 lb a.i./A is applied pre-plant, at-plant, or transplant, a llow at least 14 days before making subsequent foliar, drip and/or so il injection applications. Foliar, drip, and/or soil injection applicati ons may be applied at a rate of up to 1 lb a.i./A of oxamyl with a maximum of 2 applications and a minimum retreatment interval of 7 days..

 Do not apply more than 2 gallons of produc t (4 lbs a.i. of oxamyl) per acre per

season.

 For all other states, application rates stay as specified on the current product label.Page | 7 iv. Mitigation proposed by DuPo nt for non-bearing fruit:

 In AL, FL, GA, IN, KY, MS, NC, OH, SC, TX (except Rio Grande Valley), and WV, apply up to 2 lbs a.i./A oxamyl pre-plant, at-plant, or transplant. Foliar, drip, and/or soil injection applica tions can also be made. Apply up to 1 lb a.i./A oxamyl with a maximum of 5 applications. The minimum retreatment interval between all applications is 14 days. Do not apply mo re than 3.5 gallons of product (7 lbs a.i. oxamyl) per acre per season.

 In AR, KS, and OK, apply up to 2 lbs a.i. /A of oxamyl pre-plant, at-plant, or transplant. Foliar, drip, and/ or soil injection applications can also be made. Apply up to 1 lb a.i./A with a maximum of 3 applications. The minimum retreatment interval between all ap plications is 14 days. Do not apply more than 2.5 gallons of product (5 lbs a.i. oxamy l) per acre per season.

 For all other states, application rates stay as specified on the current product label.

v. Mitigation proposed by DuPont for peppers:

 In AR, KS, LA, MS, OK, and TX (except Ri o Grande Valley), apply up to 1 lb a.i./A oxamyl at-plant or transplant. Folia r, drip, and/or soil in jection applications can also be made. Apply up to 0.5 lb s a.i./A oxamyl with a maximum of 4 applications. The minimum retreatment in terval between all applications is 10 days. Do not apply more than 1.5 gallons of product (3 lbs a.i. oxamyl) per acre per

season.

 In NM and TX (Rio Grande Valley), apply up to 1 lb a.i./A of oxamyl at-plant or transplant. Foliar, drip and/or soil inject ion applications can al so be made. Apply up to 0.5 lbs a.i./A of oxamyl with a maximum of 5 applications. The minimum retreatment interval between all applicatio ns is 7 days. Do not apply more than 1.75 gallons of product (3.5 lbs a. i. oxamyl) per acre per season.

 For all other states, application rates stay as specified on the current product label.

c. GROUP 3 USE SITES

The use sites listed in Table 3 below, result ed in dietary risks of concern (i.e., aPADs greater than 100%) when modeled at the maximum current labeled rates and using the standard Tier II drinking water modeling approach. Du Pont submitted a proposal to mitigate risks by altering the use patterns for these crops, wh ich included lowering annua l maximum application rates in certain states, reducing the number of applications per year, and requiri ng a specific soil incorporation depth. The proposed mitigation measur es for each use site are explained in further detail below. Although the mitigation measures proposed for these crops greatly reduced the food plus drinking water dietary exposures for bot h infants and children, the modeling resulted in aPADs greater than 100% for infants. For child ren ages 1-2, the proposed mitigation reduced all modeled exposures to less than 100% of the aPAD, but for infant s, the calculated aPADs were greater than 100%. See the mode ling results in Table 3 below.Page | 8 Table 3. Results of Oxamyl Acute Aggregate Dietary Risk Assessment at the 99.9 th Percentile of Exposure Distribution for Infants and Children 1 – 2 Years Old for Existing Labeled Use Sites at DuPont Proposed Mitigated Application Rates.

Commodity %aPAD with Eating Occasions

Infants | Children 1 – 2 Worst-case Drinking Water HUC-2 Region 11 Percent Cropped Area (PCA)

Carrot 105 53 Region 8 85 Celery 121 64 Region 5 82 Eggplant 132 70 Region 8 85 Potato 102 54 Region 8 85 Tomato 143 77 Region 7 85

i. Mitigation proposed by DuPont for carrots:

 In AR, CO, IA, IL, KS, LA, MN, MO, MS , MT, ND, NE, OK, SD, TN, TX (except Rio Grande Valley), WI and WY, apply up to 2 lbs a.i./A oxamyl pre-plant, at-plant or prior to emergence. All applicati ons to the soil must be incorporated immediately to a minimum depth of 2 inches either by mechanical means or water.

 Foliar applications can be made. In AR, CO, IA, IL, KS, LA, MN, MO, MS, MT, ND, NE, OK, SD, TN, TX (except Rio Gra nde Valley), WI and WY, apply up to 1 lb a.i./A oxamyl with a maximum of 3 foliar applications.

 The minimum retreatment interval between all applications is 14 days.

 Do not apply more than 2.5 gallons of pr oduct (5 lbs a.i. oxamyl) per acre per

season.

 For all other states, application rates stay as specified on the current product label (except California, where use on carrots is not registered).

ii. Mitigation proposed by DuPont for celery:

 In MI, OH, PA, and TX (except Rio Grande Valley), apply up to 2 lbs a.i./A oxamyl pre-plant, at-plant or transplant. All applications to the soil must be incorporated immediately to a minimum de pth of 2 inches either by mechanical

means or water. Allow at least 14 da ys prior to making foliar applications.

 Foliar applications can be made. In MI, OH, PA, and TX (except Rio Grande Valley), apply up to 1 lb a.i./A oxamyl w ith a maximum of 4 foliar applications. The minimum retreatment interval between foliar applications is 7 days.

 Do not apply more than 3 gallons of produc t (6 lbs a.i. oxamyl) per acre per season.

 For all other states, application rates stay as specified on the current product label.

iii. Mitigation proposed by DuPont for eggplant:

 In AL, CO, FL, GA, IA, IL, IN, KS, KY, MI, MN, MO, MS, MT, NC, ND, NE, OH, SC, SD,TN, WI, WV, and WY, apply up to 1 lb a.i./A oxamyl as a foliar, drip, or soil injection application with a maximu m of 4 foliar applications. Do not apply more than 2 gallons of product (4 lb s a.i. oxamyl) per acre per season.

11 The HUC-2 region listed in the table represents the wors t-case scenario which is assumed to be protective of all

other regions.Page | 9  In AR, KS, LA, OK, and TX (except Rio Gr ande Valley), apply up to 1 lb a.i./A oxamyl as a foliar, drip, or soil injecti on application with a maximum of 3 foliar applications. Do not apply more than 1.5 gallons of product (3 lbs a.i. oxamyl) per

acre per season.

 The minimum retreatment interval between all applications is 10 days.

 For all other states, application rates stay as specified on the current product label.

iv. Mitigation proposed by DuPont for potato:

 In AL, AR, FL, GA, KS, LA, MS, NC, OK, SC and TX (except Rio Grande Valley), apply up to 2 lbs a.i./A oxamyl at planting. Incorporate to a minimum depth of 2 inches either by mechanical means or water.

 Foliar applications can be made. Apply up to 1 lb a.i./A oxamyl with a maximum of 4 applications.

 The minimum retreatment interval between all applications is 14 days.

 Do not apply more than 3 gallons of produc t (6 lbs a.i. oxamyl) per acre per season.

 For all other states, application rates stay as specified on the current product label.

v. Mitigation proposed by DuPont for tomato:

 In AL, AR, DE, FL, GA, IA, IL, IN, KY, LA, MD, MI, MN, MS, NC, NJ, NY, OH, PA, SC, TN, TX (except Rio Grande Valley), WV, VA, and WI, apply up to 2 lbs a.i./A oxamyl at-plant or transplant. In corporate to a minimum depth of 2 inches either by mechanical means or water.

 Foliar, drip and/or soil injection applicati ons can be made. Appl y up to 1 lb a.i./A oxamyl with a maximum of 7 applications.

 The minimum retreatment interval between all applications is 7 days.

 Do not apply more than 4 gallons of produc t (8 lbs a.i. oxamyl) per acre per season.

 For all other states, application rates stay as specified on the current product label.

For several reasons, discussed in further deta il below, EPA believes that actual dietary exposures of infants to oxamyl residues on carrots , celery, eggplant, potato, and tomato are less

than 100% of the aPAD and below EPA’s level of concern. Sensitivity analyses and the weightof-evidence suggests that, provided mitigation is incorporated into oxamyl product labels, actual exposures to infants are expected to be less than 100% of the aPAD. Specifically, the registrant conducted an assessment (MRID 48462501), which includes proposed mitigations (i.e. reductions in label guidance for both rates and numbers of applications on selected crops and regions) and regional PCA refinements excluding major crops (i.e., corn, soybeans, and wheat) to demonstrate that the exposures to infants for Group 3 use sites are expected to be less than 100% of the aPAD. DuPont will submit revised oxamy l product labels with the proposed mitigation, and once an on-going project to revise EPA’s PCA policy is completed, modeling for use of oxamyl on carrots, celery, eggplant, potato, and to mato will be reevaluated to confirm that

aPADs are below the level of concern.

There are three major factors in EPA’s dr inking water modeling that influence the amount of a pesticide active ingredient and the estimated drinking water concentrations (EDWC) in a given watershed. The three factors are the a pplication rate, estimates of the percent of the crop treated in a watershed (PCT), and the estimated percent of th e cropped area in a watershedPage | 10 (PCA). For screening-level drinking water modeling, EPA make s certain assumptions about

each of these factors which are intended to be conservative and protective of all scenarios. However, application of these standard paramete rs to the oxamyl case likely overestimates drinking water exposures and thus risk, due to th e relatively small acreage of most of the crops for which oxamyl is registered for use.

EPA models all applications of a pesticide at the maximum labeled application rate because that rate may be legally applied by pe sticide users. The Agency acknowledges that actual application rates are depende nt on pest pressure, weather, a nd other factors, and that rates lower than the maximum are frequently used to c ontrol pests. For oxamyl, EPA has survey data indicating that rates lower than the legally-all owed maximum are often applied by growers, but

these data are difficult to convert to a national or regional value th at can be input to the drinking water model. For all of these reasons, EPA models all applications, for ox amyl and other single chemical assessments, at the maximum rate.

For the second factor, percent crop treated in a watershed, the Agency’s drinking water assessment assumes 100 percent of the cropped area is treated with the pa rticular pesticide of interest. Although EPA knows that realistically less than 100% of planted acres of the Group 3 crops are likely treated with oxa myl at the large HUC-2 watershed level, EPA lacks the data to confidently quantify the PCT on a small watershed scale. Thus, the default assumption of 100% is used in drinking water modeling. However, nati onal survey data indicate s that the percent of the crop treated for Group 3 use site s is significantly le ss than 100%. For a five year period from 2006 to 2010, the average PCT for celery treated with oxamyl was approximately 40%; for potatoes, less than 20%; and for carrots and to matoes, less than 5% of the crop was treated (Source: GfK Kynetec, 2006-2010). While the PCT does vary regionally, the highest PCT reported at the state level in the survey da ta for any of the Group 3 use sites was 52%.

The third major factor that affects dr inking water modeling, PCA, represents the percentage of total agricultural land area within a watershed, and except for four main crops, PCAs do not distinguish between different crops grown within th at area. The national default

PCA of 87% is used as a cons ervative screening-level estimate for national-level drinking water assessments. This represents the HUC-8 waters hed with the maximum amount of agriculture in

the nation. At the next level of refinement, EPA uses regional default PCAs for each of the 18 largest hydrologic regions (HUC-2 12 ) in the contiguous United States 13 . Because PCAs for the HUC-2 regions are selected from the highest PCA observed in any of its constituent HUC-8 watersheds, they are the highest estimates for the entire region.

To date, EPA has determined crop-specific PC As only for four major field crops: corn, soybeans, wheat, and cotton. However, when modeling any crop other than corn, soybeans, wheat, or cotton, a default PCA, comprised of all agricultural land, is us ed. In 1999, the Federal Insecticide, Fungicide, and R odenticide Act (FIFRA) Scien tific Advisory Panel (SAP) determined that EPA did not have enough data to select crop-specific PCAs for crops other than the four field crops mentioned above. Out of th e four major field crops, oxamyl is registered for use on cotton only. All other use sites for oxamy l are smaller acreage crops such as vegetables

12 HUC-2 = 2-digit hydrological unit codes, HUC8 = 8-digit hydrological unit codes (smaller watershed area)

13 See the HUC-2 map provided in Attachment 1.Page | 11 and fruits. Because the majority of crops la beled for oxamyl use are relatively small acreage specialty crops rather than high acreage field crop s, EPA believes that it is unlikely that 87% of any HUC-2 watershed will be dedicated to the smaller acreage fruit and vegetable crops of Group 3 use sites. Consequentl y, the standard PCAs can be e xpected to overestimate the land area to which oxamyl can be applied.

Carrots: The default PCA for HUC-2 Region 8 is 85%, and this region represents the worst-case modeling scenario for carrots, resulting in the highest EDWC. Due to similar soil and weather patterns, HUC-2 Regions 11 and 12 also had similarly high EDWCs. HUC-2 Regions 8, 11, and 12 are made up of Oklahoma, Louisiana, Ar kansas, most of Texas, and smaller parts of Kansas, Mississippi, and several other neighbor ing states. Although EPA has not determined a specific PCA for carrots, carrot acreage in these re gions is extremely small and limited to several counties, and oxamyl treated ca rrot acreage is even smaller (MRID 48462501). The major crops grown in HUC-2 Regions 8, 11, and 12 are soyb eans, corn, cotton, rice, small grains, and pastureland, with carrots occupying only a ve ry small portion of available cropland. As mentioned earlier, out of four major field crops, oxamyl is registered for use on cotton only, but all four major crops contribute to the default regional PCA. From what is known about carrot and other crop acreage and usage of oxamyl in these regions, EPA be lieves that the actual PCAs for oxamyl-registered crops based on HUC-8 wate rsheds are well below the currently used 85% PCA adjustment factor.

EPA conducted a sensitivity analysis for HUC-2 Region 8, using a PCA of 65% to

determine whether the estimated PCAs would n eed to be significantly lower for dietary exposures to be below EPA’s level of concern; this number was origin ally proposed by the oxamyl technical registrant, and while EPA cannot definitively c onfirm this figure, the lower

number is not inconsistent with the nationa l average and other av ailable crop-specific information. Based on this analysis, dietary exposu re to infants was calculated to be 80% of the aPAD. With DuPont’s proposed mitigation for us e of oxamyl on carrots and actual use intensity of oxamyl on carrots and other cr ops, EPA believes that exposure in drinking water would be

lower than the assumed threshold concentration of 80 μg/L and would have a low potential to exceed dietary risks of concern from oxamyl use on carrots. EPA will confirm that the aPAD for carrots is below the level of concern once ongoi ng revisions to EPA’s PCA policy have been completed.

Celery: HUC-2 Region 5, comprised of large parts of Ohio, Indiana, Kentucky, Pennsylvania, and West Virginia and small pa rts of Illinois, Tennessee, and other surrounding states, was the worst-case modeling scenario, wi th the highest EDWC for celery. The default PCA for this region is 82%. HUC-2 Regions 4 (Michigan) and 11 (Oklahoma and parts of Texas, Kansas, and Arkansas) also had high EDWC s. The major agricultural uses in HUC-2 Regions 4, 5, and 11 are corn, soybeans, small grains, and pasturela nd with celery occupying only a very small portion of av ailable cropland. All major cr ops, however, contribute to the default regional PCA. From what is known a bout celery and other oxamy l-registered crops in these regions, actual PCAs based on HUC-8 wate rsheds are expected to be well below the currently used 82% PCA adjustment factor.Page | 12 EPA conducted a sensitivity analysis for HUC -2 Region 5 using a PCA of 53%. This number was proposed by the technical registrant , and while EPA cannot definitively confirm this figure, it is not inconsistent w ith the national average and other available information. Based on this analysis, dietary exposure to infants from celery was calculated to be 78% of the aPAD. With DuPont’s proposed mitigation for use of oxamyl on celery and the actual use intensity of oxamyl on celery and other crops in the region, EPA believes that exposure in drinking water

would be lower than the assumed threshold concen tration of 80 μg/L and has a low potential to exceed dietary risks of concern from oxamyl uses on celery. EPA will confirm that the aPAD for celery is below the level of concern once ongoing revisions to EPA’s PCA policy have been completed.

Eggplant: HUC-2 Region 8, with a default PCA of 85%, resulted in the worst-case modeling scenario for eggplant. HUC-2 Regi ons 11 and 12 also had notably high EDWCs. Eggplant production in these regions is limited to a few counties and encompasses extremely low acreage (MRID 46482501). Again, the major agricultural uses in these regions, which consume a large share of available cropl and and contribute to the defaul t regional PCA, are soybeans, corn, cotton, rice, small grains , and pastureland. From what is known about eggplant and other oxamyl-registered crop acreage, actual PCAs ba sed on HUC-8 watersheds are expected to be well below the currently used 85% PCA adjustment factor.

EPA conducted a sensitivity analysis for HUC-2 Region 8 using a PCA of 44%, and dietary exposure to infants from eggplant was calculated to be 69% of the aPAD. The PCA adjustment factor used in the sensitivity analysis was estimated by removing the major field crops corn, soybeans, and wheat from the calculati on because they are not registered use sites for oxamyl. With DuPont’s proposed mitigation fo r use of oxamyl on eggplant and the actual use intensity of oxamyl on eggplant, EPA believes th at exposure in drinking water would be lower

than the assumed threshold con centration of 80 μg/L and has a low potential to exceed dietary risks of concern from oxamyl uses on eggplant. EPA will confirm that the aPAD for eggplant is below the level of concern once ongoing revision s to EPA’s PCA policy have been completed.

Potato 14 : For potato, HUC-2 Region 8, with a de fault PCA of 85%, resulted in the worst-case modeling scenario. Due to similar soil and weather patterns in HUC-2 Regions 11 and 12, these regions also had high calculated ED WCs. Again, the major agricultural uses in these regions, which consume a large share of available cropland, are soybeans, corn, cotton, rice, small grains, and pastureland. Potatoes ar e not a major crop produced in these regions, and account for only a very small portion of av ailable cropland (MRID 48462501). However, presence of major crops like corn, soybean, and small grains contribute to the default regional PCA calculations and consequent ly, higher EDWCs. From what is known about potato and other oxamyl-registered crops in these regions, actual PCAs based on HUC-8 watersheds are expected to be well below the curren tly used 85% PCA adjustment factor.

EPA conducted a sensitivity analysis for HUC -2 Region 8 using a PCA of 69%. This number was proposed by the technical registrant , and while EPA cannot definitively confirm this

14 HUC-2 Region 17 for the Pacific No rthwest, including Idaho, had an estimated drinking water concentration

below the 80 μg/L threshold based on currently labeled use directions, and thus is not expected to be of risk

concern.Page | 13 figure, it is not inconsistent w ith the national average, and othe r available information. Based on this analysis, dietary exposure to infants from potato was calculated to be 83% of the aPAD. With DuPont’s proposed mitigation for use of oxa myl on potatoes and the actual use intensity of oxamyl in these regions, EPA believes that exposur e in drinking water would be lower than the assumed threshold concentration of 80 μg/L and has a low potential to exceed dietary risks of concern from oxamyl uses on potato. EPA will confirm that the aPAD for potatoes is below the level of concern once ongoing revisions to EPA’s PCA policy have been completed.

Tomato: HUC-2 Region 7, with a default PCA of 85%, resulted in the worst-case modeling scenario for tomato, although Regions 3, 4, and 5 also had high EDWCs. The regions are made up of the southeastern and Great La kes states along with pa rts of Kentucky, West Virginia and several other states. The major ag ricultural uses in these regions are pastureland, soybeans, corn, cotton, and small grains with to matoes accounting for only a very small portion of available cropland. From what is known a bout tomato and other oxamyl-registered crop acreage, actual PCAs based on HUC-8 watersheds are expected to be well below the currently used 85% PCA adjustment factor.

EPA conducted a sensitivity analysis for HUC-2 Region 7 using a PCA of 56%, and dietary exposure to infants from tomatoes was calculated to be 94% of the aPAD. The PCA adjustment factor used in the sensitivity analysis was estimated by removing the major field crops corn, soybeans, and wheat from the calculati on because they are not registered use sites for oxamyl. With DuPont’s proposed mitigation for use of oxamyl on tomato and actual use intensity of oxamyl in these regions, EPA belie ves that exposure in dr inking water would be

lower than the assumed threshold concentration of 80 μg/L and has a low potential to exceed dietary risks of concern from oxamyl uses on tomato. EPA will confirm that the aPAD for tomatoes is below the level of concern once ong oing revisions to EPA’s PCA policy have been completed.

EPA’s default assumptions for application rate, PCT, and PCA within the oxamyl modeling generated upper-bound con centrations of oxamyl in drinking water for the five use sites discussed above. With DuPont’s proposed mitigation for use of oxamyl on the Group 3 use sites and considering the actual use intensity of oxamyl in various HUC-2 regions, EPA believes that dietary exposure of infants to oxamyl resi dues in drinking water would be lower than the threshold concentration of 80 μg/L and below EP A’s level of concern. Furthermore, EPA will confirm this conclusion, once an on-going project to develop a vege table-specific PCA factor is completed by the Office of Pesticide Program’s Environmental Fate and Effects Division.



### IV. TROPICAL CROPS GROWN IN HAWAII AND PUERTO RICO

For additional details regarding the use of oxamyl on certain tropical crops grown in Hawaii (HI) and Puerto Rico (PR) (bananas/plant ains, ginger, pineapple, and yams), please see the following document in the oxa myl docket (EPA-HQ-OPP-2010-0028):Page | 14 - Review of Assessment of th e Potential Oxamyl Exposure to Surface Water Drinking Water Supplies in the United State, Hawaii and Puerto Rico Under Current and Proposed Mitigation

Use Guidance . F. Khan. June 29, 2011.

Except for a few particular cases, EPA has only developed PCA adjustment factors and Tier II drinking water modeling for scenarios that occur within the continental United States. For most scenarios modeled outside of the continental US, such as oxamyl scenarios for yams and pineapple grown in PR and ginger and pine apple grown in HI, Tier I modeling using the

FIRST 15 model is typically conducted. FIRST is a screening-level model which simulates upperend exposures and makes conservative assumptions . For bananas/plantain s grown in PR, more refined Tier II modeling was conduc ted, but it used a very conser vative 100% PCA adjustment

factor.

Drinking water modeling for ginger, pineappl e, and yams scenarios in HI and PR, conducted with the FIRST model, resulted in diet ary exposures above EPA’s level of concern.

Due to the conservative nature of this basic m odel, further refinement of these scenarios was used to more accurately assess real-world conditi ons relative to oxamyl use on these crops. Tier II drinking water modeling for bana nas/plantains also resulted in dietary exposures above EPA’s

level of concern due to the conservative assumption that 100% of land area is cropped.

EPA used a simplified version of the Agency’s standard procedures for calculating PCA adjustment factors for HI and PR and determin ed that the EDWCs would be lower than the threshold concentration of 80 μg/L for bananas/pl antains, ginger, pineapple, and yams and would have low potential to exceed diet ary risks of concern. EPA previously determined that EDWCs of 80μg/L or lower would result in aPADs below 100%, and thus not be of concern.



### V. SUMMARY OF RISKS / DECISION

Based on refinements to the drinking water e xposure assessment, char acterization of the use of oxamyl on specific crops, and mitigati on measures proposed by DuPont, the risks of concern associated with use of oxamyl on existi ng use sites have been adequately addressed, provided that labels are revise d as agreed upon with DuPont and submitted to the Agency for approval.

Once an on-going project to develop a vegetabl e-specific PCA factor is completed by the Office of Pesticide Program’s Environmental Fate and Effects Division, drinking water and dietary modeling for use of oxamyl on carrots, celery, eggplant, potato, and tomato will be

reevaluated to confirm that aPADs are below the level of concern. A weight-of-evidence approach, as discussed in this document, supports the finding that that actu al dietary exposures of infants and children ages 1 – 2 to oxa myl are below EPA’s level of concern.

15 FIRST = FQPA Index Reservoir Screening ToolPage | 15 

### Attachment 1 The Eighteen HUC-2 Watershed Basins of the Contiguous United States

Source: G. Orrick. Update to Drinking Wa ter Exposure Assessments for Current Uses of Oxamyl. June 15, 2010. DP Barcode 378338.