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Docket Number EPA-HQ-OPP-2010-0751 

www.regulations.gov

Methomyl Summary Document 

Registration Review: Initial Docket 

September 2010 

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TABLE OF CONTENTS 

 Page # 

I. Preliminary Work Plan (PWP) 4 

II. Fact Sheet 11 

III. Summary of Data Gaps 17 

 

This Preliminary Work Plan and Fact Sheet summarize the Environmental Protection Agency’s 

current position based on the following documents: 

1. Registration Review: Preliminary Problem Formulation for Environmental Fate, 

Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments for 

Methomyl, July 16, 2010. 

2. Methomyl: Registration Review Scoping Document for Human Health Assessments, 

 July 13, 2010. 

3. Methomyl Screening Level Usage Analysis (SLUA), October 19, 2009. 

4. Methomyl: Review of Human Incidents, May 20, 2010. 

All supporting documents for the registration review of methomyl are located in docket EPAHQ-OPP-2010-0751 at www.regulations.gov. 
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I. PRELIMINARY WORK PLAN – METHOMYL 

Introduction

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review 

program. All pesticides distributed or sold in the United States (U.S.) generally must be 

registered by the Environmental Protection Agency (EPA or the Agency), based on scientific 

data showing that they will not cause unreasonable risks to human health or the environment 

when used as directed on product labeling. The registration review program is intended to make 

sure that, as the ability to assess risk evolves and as policies and practices change, all registered 

pesticides continue to meet the statutory standard of no unreasonable adverse effects to human 

health or the environment. Changes in science, public policy, and pesticide use practices will 

occur over time. Through the registration review program, the Agency periodically reevaluates 

pesticides to make sure that as change occurs, products in the marketplace can be used safely. 

Information on this program is provided at: http://www.epa.gov/oppsrrd1/registration_review/. 

The Agency is implementing the registration review program pursuant to Section 3(g) of 

the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each 

registered pesticide every 15 years to determine whether it continues to meet the FIFRA standard 

for registration. The Agency will consider benefits information and data as required by FIFRA. 

The public phase of registration review begins when the initial docket is opened for each case. 

The docket is the Agency’s opportunity to state what it knows about the pesticide and what 

additional risk analyses and data or information it believes are needed to make a registration 

review decision. After reviewing and responding to comments and data received in the docket 

during this initial comment period, the Agency will develop and commit to a final work plan and 

schedule for the registration review of methomyl. 

Methomyl is an N-methyl carbamate insecticide currently registered for use on a wide 

variety of sites including field, vegetable, and orchard crops, and on turf (sod farms only). 

Methomyl is generally a restricted use pesticide [based on percent active ingredient (a.i.)] and 

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 Eligibility Decision (RED) was completed in 1998. Methomyl is the primary 

metabolite of thiodicarb, which is also an insecticide. The thiodicarb registration review docket 

(EPA-HQ-OPP-2009-0432) opened on December 16, 2009. 

Methomyl and thiodicarb are members of the N-methyl carbamate (NMC) class of 

chemicals that share a common mechanism of toxicity and inhibit acetylcholinesterase (AChE) 

by carbamylation of the serine hydroxyl group located in the active site of the enzyme. The 

“Revised N-Methyl Carbamate Cumulative Risk Assessment” was completed in September 2007 

and is available in the docket at EPA-HQ-OPP-2007-0935. 
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Anticipated Risk Assessment and Data Needs

The Agency intends to require data needed to conduct a comprehensive ecological risk 

assessment, including an endangered species risk assessment, and a revised human health risk 

assessment for all uses of methomyl. Below is a summary of the issues relevant to the 

registration review of methomyl and the data the Agency anticipates requiring. 

Ecological Risk: 

 The most recent comprehensive risk assessment for methomyl was conducted in 1998 in 

support of the Reregistration Eligibility Decision (RED) document. 

 

 The Agency has conducted several assessments on some endangered species, but has not 

conducted an ecological risk assessment that supports a complete endangered species 

determination for methomyl. The ecological risk assessment planned during registration 

review will allow the Agency to determine whether methomyl’s use has “no effect” or 

“may affect” federally listed threatened or endangered species (listed species) or their 

designated critical habitats. When an assessment concludes that a pesticide’s use “may 

affect” a listed species or its designated critical habitat, the Agency will consult with the 

U.S. Fish and Wildlife Service (FWS) and/or National Marine Fisheries Service (NMFS) 

(the Services), as appropriate. 

 The Agency anticipates needing the following data in order to conduct a complete 

ecological risk assessment, including a complete endangered species assessment, for 

methomyl: 

 GDLN 835.2240 – Aqueous photolysis 

 GDLN 835.4100 – Aerobic soil metabolism 

 GDLN 835.4300 – Aerobic aquatic metabolism 

 GDLN 835.4400 – Anaerobic aquatic metabolism 

 GDLN 850.2100 – Avian oral toxicity (passerine species) 

 GDLN 850.2300 – Avian reproduction study (mallard duck) 

 GDLN 850.4100 – Terrestrial plant toxicity: Tier II Seedling Emergence 

 GDLN 850.4150 – Terrestrial plant toxicity: Tier II Vegetative Vigor 

 GDLN 850.4400 – Aquatic plant growth: vascular plants 

 GDLN 850.5400 – Aquatic plant growth: nonvascular plants 

Please refer to the “Registration Review: Preliminary Problem Formulation for Environmental 

Fate, Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments for 

Methomyl,” dated July16, 2010, for a more detailed discussion of the anticipated ecological risk 

assessment and data needs. 
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Human Health Risk: 

 The most recent comprehensive human health risk assessment for methomyl was 

completed in support of the 1998 RED. A dietary assessment was completed for 

methomyl as part of the NMC Cumulative Risk Assessment. 

 Since the last human health exposure and risk assessment in support of the 1998 RED the 

crop use sites and application scenarios have remained the same with the exception of the 

cancellation of methomyl use on strawberries, the pending cancellation of the grape use, 

and the restriction on handheld devices. 

 A revised dietary risk assessment, may be needed to include updated percent crop treated 

estimates, updated monitoring data, changes in toxicological endpoints, and revised 

estimated drinking water concentrations. 

 The methomyl tolerance expression in 40 CFR 180.253 will be reviewed during 

registration review to ensure that it appropriately covers the metabolites and degradates 

of methomyl and that it specifies the residues to be measured for each commodity. Any 

proposed revisions would be to the chemical description rather than the individual 

tolerance levels. 

 A residential handler exposure assessment may be needed during registration review. 

Even though there are currently no homeowner uses for methomyl, there is a potential for 

exposure to baits in public areas. In addition, a residential post-application assessment 

may be needed to support the use of methomyl on sod farms. 

 Revised occupational handler and postapplication assessment may be needed based on 

the most current toxicity profile and Agency policies. 

 Due to the rapid onset and recovery of AChE effects from methomyl, an acute aggregate 

risk assessment is the only appropriate aggregate assessment that may be needed to 

support registration review. This acute assessment would incorporate any new point of 

departures or uncertainty factors identified for methomyl. 

 The Agency anticipates requiring the following data in order to conduct a complete 

human health risk assessment for methomyl: 

o GDLN 870.7800 – Immunotoxicity Study 

o Non-guideline – Acute Inhalation Study This acute inhalation study would 

provide AChE data showing the time to peak AChE inhibition as well as the doseresponse of AChE inhibition at the peak inhibition. A study protocol should be 

provided to the Agency for review before the onset of such study. 
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 Prior to a final registration review decision for methomyl, the Agency will determine if 

there is any new information, such as new hazard or exposure data or information on 

changes to the use pattern, that would affect the cumulative risk assessment. Should the 

Agency determine that new information on methomyl is available that could potentially 

impact the cumulative risk assessment and result in a risk of concern, the Agency will 

revisit the cumulative risk assessment. 

 Please refer to the “Methomyl: Registration Review Scoping Document for Human Health 

Assessments,” dated July 13, 2010, available in the docket, for a detailed discussion of the 

anticipated human health risk assessment and data needs for methomyl. 

Other Anticipated Data Needs: 

 GDLN 830.7050 UV/Visible Light Absorption – this study is a new data requirement 

under 40 CFR part 158 (Product Chemistry Data Requirements) for registration of a 

pesticide (food and non-food uses). The Agency anticipates requiring this study to obtain 

basic information about the compound’s identity/composition and the wavelengths at 

which the compound may be susceptible to photochemical degradation.

Endocrine Disruptor Screening Program

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 

Screening Program (EDSP) to determine whether certain substances (including pesticide active 

and other ingredients) may have an effect in humans or wildlife similar to an effect produced by 

a “naturally occurring estrogen, or other such endocrine effects as the Administrator may 

designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine related effects caused by the substance, and 

establish a quantitative relationship between the dose and the E, A, or T effect. 

Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first 

group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. 

This list of chemicals was selected based on the potential for human exposure through pathways 

such as food and water, residential activity, and certain post-application agricultural scenarios. 

This list should not be construed as a list of known or likely endocrine disruptors. 

Methomyl is among the group of 58 pesticide active ingredients on the initial list to be screened 

under the EDSP. For information on the status of the orders issued under the EDSP for each 

chemical, please visit our website at http://www.epa.gov/endo/ and click on the "Status of EDSP 
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Orders/DCIs" in the Highlights Box. Additional information on the EDSP, including the policies 

and procedures, the list of 67 chemicals, the test guidelines and the Tier 1 screening battery, can 

also be found at this website. 

Timeline

 

The Agency has created the following estimated timeline for the completion of the methomyl 

registration review. 

Registration Review for Methomyl – Projected Registration Review Timeline

Activities Estimated Date 

Opening the Docket 

Open Docket and Public Comment Period 2010 – September 

Close Public Comment 2010 – November 

Case Development 

Final Work Plan 2011 – February 

Issue DCI 2011 – Oct – Dec 

Data Submission 2013 – Oct –Dec 

Open Public Comment Period for Draft Risk Assessments 2015 – April – June 

Close Public Comment Period 2015 – July – Sept 

Registration Review Decision 

Open Public Comment Period for Proposed Registration Review 

Decision 

 

2015 – Oct – Dec 

Close Public Comment Period 2016 – Jan - March 

Registration Review Decision and Begin Post-Decision Follow-up 2016 

Total (years)1 6 

1. An assessment of the potential cumulative risk from the NMC class of insecticides may impact this time estimate. 

Guidance for Commenters

The public is invited to comment on EPA’s preliminary registration review work plan and 

rationale. The Agency will carefully consider all comments, as well as any additional 

information or data provided in a timely manner, prior to issuing a final work plan for the 

methomyl case. 

Trade Irritants

Through the registration review process, the Agency intends to solicit information on trade 

irritants and, to the extent feasible, take steps toward facilitating irritant resolution. Growers and 

other stakeholders are asked to comment on any trade irritant issues resulting from lack of 
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Maximum Residue Limits (MRLs) or disparities between U.S. tolerances and MRLs in key 

export markets, providing as much specificity as possible regarding the nature of the concern. 

Environmental Justice

EPA seeks to achieve environmental justice, the fair treatment and meaningful involvement of all 

people, regardless of race, color, national origin, or income, in the development, implementation, 

and enforcement of environmental laws, regulations, and policies. To help address potential 

environmental justice issues, the Agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have 

atypical, unusually high exposure to methomyl compared to the general population. Please 

comment if you are aware of any sub-populations that may have atypical, unusually high 

exposure, compared to the general population. 

Water Quality

Methomyl and thiodicarb are not identified as causes for any water bodies listed as impaired 

under section 303(d) of the Clean Water Act (based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=88

5, accessed April 22, 2010). In addition, no Total Maximum Daily Loads (TMDL) have been 

developed for thiodicarb or methomyl (based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id

=885&p_pollutant_group_name=PESTICIDES, accessed April 22, 2010). More information on 

impaired water bodies and TMDLs can be found at http://www.epa.gov/owow/tmdl/. The 

Agency invites submission of water quality data for these pesticides. To the extent possible, data 

should conform to the quality standards in Appendix A of the OPP Standard Operating 

Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in OPP’s 

Registration Review Risk Assessment and Management Process (see: 

http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf), in order to ensure 

they can be used quantitatively or qualitatively in pesticide risk assessments. 

Additional Information

Stakeholders are also specifically asked to provide information and data that will assist the 

Agency in refining risk assessments, including any species-specific ecological effects 

determinations. The Agency is interested in receiving the following information: 

1. Confirmation on the following label information. 

a. sites of application 

b. formulations 

c. application methods and equipment 

d. maximum application rates 
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e. frequency of application, application intervals, and maximum number of 

applications per season and per year 

f. geographic limitations on use 

2. Use or potential use distribution (e.g. geographical distribution of relevant uses). 

3. Use history. 

4. Median and 90th percentile reported use rates (lb/A, lb 1K sq.ft) from usage data – 

national, state and county. 

5. Application timing (date of first application and application intervals) by use – national, 

state, and county. 

6. Usage/use information for non-agricultural uses. 

7. Directly acquired county-level usage data (not derived from state level data). 

a. maximum reported use rate (lb/cc) from usage data – county 

b. median and 90th percentile number of applications – county 

c. total pounds per year – county 

d. the year the pesticide was last used in the county/sub-county area 

e. the years in which the pesticide was applied in the county/sub-county area 

8. Typical application interval (days). 

9. State or local use restrictions. 

10. Ecological incidents specific to methomyl (non-target plant damage and avian, fish, 

reptilian, amphibian, mammalian mortalities, and bee or beneficial insect mortalities) not 

already reported to the Agency. 

Next Steps

After the 60-day comment period closes, the Agency will consider and respond to any comments 

received in a timely manner and then expects to issue a Final Work Plan in February of 2011 for 

methomyl. 
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II. FACT SHEET 

Background Information

 The registration review case number for methomyl is: 0028. 

 Methomyl PC Code: 090301; CAS # 16752-77-5. 

 Methomyl was first registered in the United States in 1968. 

 A Reregistration Eligibility Decision (RED) was completed in 1998. 

 Technical registrant: E.I du Pont de Nemours and Company 

 There are 9 FIFRA Section 3 product registrations and 18 Special Local Needs (24c). 

 The non-agricultural products are formulated with cis-9-Tricosene that acts as a fly 

attractrant. 

 Pesticide Re-evaluation Division Contact: Yan Donovan (donovan.yan@epa.gov). 

 Registration Division Contact: Thomas Harris (harris.thomas@epa.gov) 

Use and Usage Information

 Methomyl is registered for use as an insecticide to control a number of pests in agricultural 

and non-agricultural areas, but it does not have any registered residential uses. Methomyl is 

used primarily on sweet corn, lettuce, onions, and tomatoes. 

 All methomyl agricultural products are designated as a restricted use pesticide due to high 

acute toxicity to humans.

 

 Methomyl has low percentage formulations (less than 1% a.i.), used as scatter bait, bait 

station, and paste formulations that are not designated as restricted use.

 Based on a Screening Level Usage Analysis conducted by the Agency (USEPA 2009a), 

using data from 2001 to 2007, there is an estimated 800,000 pounds of methomyl used 

per year. 

Recent and Pending Actions 

 The use of methomyl on strawberries was deleted from labels in October 2007. 

 The use of methomyl on grapes is going through the process of being deleted from labels. 

 Methomyl was included in the cumulative risk assessment completed for the N-methyl 

carbamate group of pesticides in September 2007. 
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Ecological Risk Assessment Status

The following are key findings from the most recent ecological risk assessments regarding the 

environmental fate, ecological effects and risks of methomyl. Please refer to “Registration 

Review: Preliminary Problem Formulation for Environmental Fate, Ecological Risk, 

Endangered Species, and Drinking Water Exposure Assessments for Methomyl,” dated July16, 

2010, located in the docket, for a detailed discussion. 

Ecological Risks: 

 The most recent comprehensive risk assessment was conducted to support the 

Reregistration Eligibility Decision (RED) document in 1998. In this assessment the 

Agency determined that acute and chronic risk quotients (RQ) exceeded risk levels of 

concern (LOC) for endangered/threatened birds (and, thus, reptiles and terrestrial-phase 

amphibians), mammals, and aquatic vertebrates (and, thus, aquatic-phase amphibians) 

and invertebrates. 

 The Agency consulted with the U.S. Fish and Wildlife Service (USFWS) in 1989 

regarding methomyl impacts on some endangered species. As a result, the USFWS 

issued a formal Biological Opinion (BiOp) that identified reasonable and prudent 

measures and alternatives to mitigate effects of methomyl use on endangered species. 

The reasonable and prudent measures and alternatives noted in the biological opinion 

were considered in EPA's County Bulletins. While pesticide users were encouraged to 

follow the measures in the County Bulletins, they were not enforceable under FIFRA. 

That biological opinion was based on what are now outdated label instructions and use 

sites for methomyl and the Agency's assessment was based on methodologies that have 

since been refined. Therefore, the agency will be reassessing the uses of methomyl 

during registration review and initiating consultation as appropriate, to determine 

ultimately what if any enforceable limitations on its use are necessary to ensure 

protection of federally listed threatened or endangered species and their designated 

critical habitat. 

 

 On April 1, 2003, the Agency initiated formal consultation with the National Marine 

Fisheries Service (NMFS) relative to an effects determination regarding methomyl’s 

potential effects to 26 Environmentally Significant Units (ESUs) of Pacific salmon and 

steelhead. In response to the Agency's effects determination and consultation, NMFS 

issued a BiOp in 2009. In the BiOp, NMFS concluded that the use of methomyl is likely 

to jeopardize the continued existence of 18 salmonid ESUs and destroy or adversely 

modify designated critical habitat for 16 ESUs. To achieve the protections sought under 

the reasonable and prudent alternatives proposed by NMFS, the Agency plans to 

implement several measures that would be accomplished by changes to pesticide 

labeling. These include buffers, wind speed restrictions, and soil moisture restrictions. 
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 On July 20, 2007, the Agency submitted a risk assessment and effects determination to 

the USFWS for the California red-legged frog (Rana aurora draytonii) (CRLF) (and its 

designated critical habitat) relative to the use of methomyl in California. A Likely to 

Adversely Affect (LAA) effects determination was made based on the potential for direct 

effects to both aquatic- and terrestrial-phase CRLF and the potential for indirect effects to 

prey taxa (for both aquatic- and terrestrial-phase CRLF). Additionally, a ‘habitat 

modification’ effects determination was made for CRLF designated critical habitat based 

on the potential for effects to prey items for both aquatic- and terrestrial-phase CRLF. 

Human Health Risk Assessment Status

The following are key findings from the human health risk assessments conducted for methomyl 

registered uses. Please refer to the “Methomyl: Registration Review Scoping Document for Human 

Health Assessments,” dated July 13, 2010, located in the docket for a detailed discussion of the human 

health risk assessment status. 

Hazard Characterization: 

 Methomyl is a member of the N-methyl carbamate (NMC) class of chemicals sharing a 

common mode of action with other NMC pesticides that act to inhibit the 

acetylcholinesterase enzyme (AChE), typically within 30-60 minutes, at low dose levels 

and across species. Reactivation of the enzyme and therefore recovery of AChE activity 

occurs within hours for methomyl as is typical for the NMCs. Acute exposure, therefore, 

is the main duration of concern for methomyl. 

 Methomyl is classified as “not likely” to be a human carcinogen based on carcinogenicity 

studies in rats and mice. 

Dietary (Food and Drinking Water): 

 A dietary assessment was conducted in association with the 1998 RED. Dietary risk 

estimates for methomyl were below EPA’s level of concern for all population subgroups. 

 In conjunction with the 2007 NMC cumulative assessment, a highly refined acute single 

chemical dietary risk assessment was conducted using updated estimated environmental 

concentrations. The results of the analysis indicated that estimated acute dietary 

exposure and risk exceeded EPA's level of concern. A sensitivity analysis was also 

conducted to determine the foods or food forms which contribute the most to the 

exposure estimates. Methomyl residues in grapes were the most significant source of 

dietary exposure. When grapes are excluded from the dietary assessment, dietary risk 

estimates are below EPA’s level of concern. The use on grapes is being deleted from 

methomyl labels due to dietary risk concerns and will be effective in 2010. 
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 Tier II drinking water exposure assessments were completed for methomyl in 2007, 2009, 

and 2010 to evaluate currently labeled uses. The assessments used data submitted after 

the 1998 RED, maximum application rates identified on product labels, percent cropped 

area factors, and current aquatic exposure models. Exposure estimates for use on some 

crops, such as lettuce, were higher than those previously assessed. Additional assessment 

refinements are necessary to clarify which currently labeled use patterns may result in 

drinking water exposure that may exceed dietary levels of concern. 

Residential: 

 Three post-application exposure scenarios were assessed in the 1998 RED. All three 

scenarios resulted in risks that were below the Agency’s concern. 

 

Aggregate: 

 The aggregate risk assessment evaluates the combined risk from dietary exposure (food 

and water) and any non-occupational (residential) uses. An acute aggregate dietary 

exposure assessment (food plus drinking water) resulted in risks above the Agency’s 

level of concern for one drinking water scenario. As mentioned previously, additional 

refinements are necessary for the labeled use patterns that will result in a highly refined 

water assessment for methomyl. 

Occupational: 

 All occupational handler exposures considered in the 1998 RED did not exceed the 

Agency’s level of concern with varying levels of personal protective equipment (i.e., 

double layer clothing, chemical resistant gloves, dust/mist respirators) and/or engineering 

controls (i.e., water soluble bags). 

 Past methomyl risk assessments rely in part on data from studies in which adult human 

subjects were intentionally exposed to a pesticide to determine their dermal and 

inhalation exposure. Many such studies, involving exposure to many different pesticides, 

comprise generic pesticide exposure databases such as the Pesticide Handlers Exposure 

Database (PHED) and the Agricultural Reentry Task Force (ARTF) Database. EPA has 

reviewed all the studies supporting these multi-pesticide generic exposure databases, and 

has found no clear and convincing evidence that the conduct of any of them was either 

fundamentally unethical or significantly deficient relative to the ethical standards 

prevailing at the time the research was conducted. All applicable requirements of EPA’s 

Rule for the Protection of Human Subjects of Research (40 CFR Part 26) have been 

satisfied, and there is no regulatory barrier to continued reliance on these studies. 

 Past methomyl risk assessments have also relied in part on a single human study which 

may have involved intentional exposure tomethomyl. In the course of registration 
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review EPA will reconsider these studies, as well as any other research involving 

intentional exposure of human subjects to methomyl brought to its attention. If EPA 

decides to rely on any of these studies, EPA will ensure that all applicable regulatory 

requirements are met, including but not limited to the requirements for EPA ethics review 

and Human Studies Review Board review of certain research involving intentional 

exposure of human subjects 

Cumulative Risk Characterization (CRA): 

 The Food Quality Protection Act (FQPA) requires the Agency to consider the cumulative 

risks of chemicals sharing a common mechanism of toxicity. Methomyl is a member of 

the N-methyl carbamate common mechanism group. The most recent cumulative risk 

assessment for the NMC carbamates was issued for comment on September 26, 2007 and 

is available at http://www.epa.gov/oppsrrd1/REDs/nmc_revised_cra.pdf. The cumulative 

assessment did not result in any mitigation for methomyl. 

Incidents

Ecological:

 Preliminary reviews of the Ecological Incident Information System (EIIS, version 2.1) 

and the Avian Incident Monitoring System (AIMS) were conducted on February 17, 

2010. A total of 10 incidents associated with methomyl use have been reported (8 

involving birds and 2 involving fish). The reported incidents occurred between 1976 and 

2006. 

 

 In addition to the incidents recorded in EIIS and AIMS, registrants have reported 7 minor 

fish and wildlife incidents as of February 17, 2010, all of which occurred between 2000 

and 2007. 

Human Health: 

 Both the OPP Incident Data System (IDS) and the Centers for Disease Control and 

Prevention/National Institute for Occupational Safety and Health (CDC/NIOSH) Sentinel 

Event Notification System for Occupational Risk-Pesticides (SENSOR) database were 

consulted for pesticide incident data on the active ingredient methomyl. 

 43 cases were reported in IDS from 2002 to 2010. Of these cases, thirteen resulted from 

single chemical (methomyl) use only. Five of the incidents involved intentional 

ingestion/misuse of the product. Six incidents involved agricultural handlers using 

methomyl: four in seemingly typical ways and two where equipment 

malfunctioned/leaked. The symptoms most often reported were neurological (27%) 

followed by gastrointestinal (23%) and ocular (20%). 
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 60 cases were reported in NIOSH SENSOR from 1998 to 2006. Of these cases, 21 were 

reviewed because methomyl was the only chemical used in these cases. All of the 

reviewed cases were classified as low or moderate severity. 

Tolerances and International Harmonization

 A table listing the differences between U.S. tolerances, Canadian, and CODEX MRLs for 

methomyl is included in the Methomyl: Registration Review Scoping Document for 

Human Health Assessments. Mexico has not currently established MRLs for methomyl, 

but will adopt the U.S. tolerance and\or Codex MRL for its export purposes. Any 

methomyl tolerances reassessed during the registration review process will be considered 

for possible harmonization with international MRLs. 

 Tolerances are established under 40 CFR §180.253 for residues of the insecticide 

methomyl, including its metabolites and degradates, in or on a variety of food and feed 

crops. 

Data Call-In Status 

 In response to the DCI that was issued after completion of the RED, the registrant has 

submitted multiple studies and waiver requests that are currently under review by the 

Agency. Depending upon the outcome of these reviews, additional data may be required 

to support registration review. 

 860.1300 Nature of the Residue – Plants (Tomato MRID 46387701) 

 860.1340 Residue Analytical Method (MRID 45297106) 

 860.1380 Storage Stability 

Bean seed, potato tubers, peanut nutmeat (MRID 45297101) 

Dry bulb onions (MRID 45297102) 

Sorghum grain (MRID 45297103) 

 860.1500 Crop Field Trials 

Bermudagrass and Sorghum Forage (Waiver Request)

Cotton gin trash (MRID 45297104) 

Turnip tops (MRID 45297105) 

 860.1850 Confined Rotational Crop Study (Waiver Request)

 Labels 

 Active Section 3 labels for methomyl can be obtained from the Pesticide Product Label 

System (PPLS) website: http://oaspub.epa.gov/pestlabl/ppls.home . 
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III. Summary of Data Gaps – Methomyl 

The table below summarizes all outstanding data needs for methomyl in Section I of this 

Preliminary Work Plan. 

Guideline 

Number Data Requirement 

Test 

Material 

Estimated 

Timeframe 

(Months) 

835.2240 Aqueous photolysis TGAI 24 

835.4100 Aerobic Soil Metabolism* TGAI 24 

835.4300 Aerobic Aquatic Metabolism TGAI 24 

835.4400 Anaerobic Aquatic Metabolism TGAI 24 

850.2100 Avian Oral Toxicity (passerine species) TGAI 12 

850.2300 Avian Reproduction Study (Mallard duck) TGAI 12 

850.4100 Terrestrial Plant toxicity: Tier I Seedling Emergence** TGAI 12 

850.4150 Terrestrial Plant toxicity: Tier I Vegetative Vigor** TGAI 12 

850.4400 Aquatic Plant Growth: Tier II Vascular Plants** TGAI 12 

850.5400 Aquatic Plant Growth: Tier II Algae** TGAI 12 

Non-GDLN Acute Inhalation Study TGAI 12 

870.7800 Immunotoxicity Study TGAI 12 

* Foreign Soil Taxonomic Classification. Soil taxonomic classifications for foreign soils studied 

in MRID 45473401 are necessary in order to compare the studied soils to domestic soils 

representative of methomyl use sites. 

**Registrants may opt to conduct a Tier I study, with the understanding that any adverse effects 

(even if <25%) will necessitate a Tier II study. A Tier II study will enable the Agency to 

conduct an endangered species assessment for nontarget plants.