Docket Number: EPA-HQ-OPP-2010-0119 www.regulations.gov



## Chlorpyrifos-methyl Final Work Plan Registration Review July 2010CHLORPYRIFOS-METHYL FINAL WORK PLAN

Introduction :

This is the Environmental Protection Agency’s (EPA’s) Final Work Plan for the registration review of chlor pyifos-methyl. This work plan includes the expected registration review timeline. The work plan also addresses public comments received concerning the Preliminary Work Plan in the Summary Document , which was posted in the chlorpyrifos-methyl re gistration review docket (E PA-HQ-OPP-2010-0119), and any other comments concerning the in itial docket postings. The Summary Document provided information on what EPA knows about the pesticide and what additional risk analyses and data or information the Agency believes are needed to make a registration

review decision.

The Agency is implementing the registration re view program pursuant to Section 3(g) of the Federal Insecticide, Fungicide, and Rode nticide Act (FIFRA), and will review each registered pesticide every 15 years to determ ine whether it continues to meet the FIFRA standard for registration. Ch anges in science, public polic y, and pesticide use practices will occur over time. The registration review program is intended to make sure that, as the ability to assess risk e volves and as policies and pract ices change, all registered pesticides continue to meet the statutory standard. Th e public phase of registration review begins when the initial docket is opened for each case. Information on this program is provided at: http://www.epa.gov/oppsrr d1/registration_review/

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Chlorpyrifos-methyl (Case 8011) is an organopho sphate (OP) insecticide registered for use to control a variety of insects including beetles, weevils, moth s, and grain borers. Like other OP insecticides, chlorpyr ifos-methyl acts through inhibition of acetylcholinesterase. Chlorpyrifos-methyl wa s first registered in 1985 for use on stored grain, such as wheat, barley, oats, rice, and sorghum. There are two chlorpyrifos-methyl products currently registered: a technical-g rade product, and an end-use product. Chlorpyrifos-methyl is only registered for us e as an indoor treatment for small grains in storage bins and warehouses. A Tolera nce Reassessment and Risk Management Eligibility Decision document (TRED) was i ssued for chlorpyrifos-methyl in January 2001; the TRED was finalized with the OP cumulative in 2006.

Comments Received on Preliminary Work Plan :

Multiple comments were received during the 60-day public comment period on the Preliminary Work Plan

. These comments are summarized in this document and changes to the work plan set out in the Preliminary Work Plan are explained. In the Preliminary

Work Plan , EPA also solicited comments on three specific topics: environmental justice, water body impairment, and trade irritants. No comments or information were received during the comment period c oncerning these issues.

3Anticipated Risk Assessment and Data Needs:

The Agency anticipates that no quant itative ecological risk assessment, quantitative endangered species assessment, or drinking water assessment will be needed for chlorpyrifos-methyl because all register ed uses are indoor uses only. Chlorpyrifosmethyl is applied by manual and automatic sp rayer in self-containe d units with little potential for offsite transport. The app lication method does not allow for drift to terrestrial areas or to water bodies. The appl ication is not intended for moist areas and does not contain amounts of active ingredient sufficient for runoff to be a concern. In addition, the use pattern is unlikely to resu lt in exposure to aquatic resources or groundwater and thus drinking water is un likely to be impacted by this use.

The Agency anticipates conducting human heal th risk assessments for chlorpyrifosmethyl. Below is a summary of the issues relevant to the re gistration review of chlorpyrifos-methyl.

Human Health Risk:

• A comprehensive human health risk a ssessment was conducted in April 2000 to support the 2001 Tolerance Reassessment and Risk Management Decision (TRED).

• The TRED did not include a residential or drinking water risk assessment. There are no registered uses of chlorpyrifos-methyl that result in resi dential exposure or exposure from drinking water. Exposure to chlorpyrifos-methyl may occur via food, and occupational activities may result in dermal and inhalation exposures.

• During the reregistration of chlorpyrif os, the Agency determined that the metabolite TCP, common to both chlorpyrifos and chlorpyfios-methyl, is no longer considered to be of toxicologi cal concern, and recommended the removal

of TCP from the tolerance expression of chlorpyrifos -methyl. Tolerances for resides in/on plant and anim al commodities should be changed to be expressed in terms of parent chlorpyrifos-methyl only (40 CFR 180.419).

• During registration review, the chlorpyrif os-methyl tolerance expression (40 CFR 180.419) will be reviewed to ensure that it appropriately covers the metabolites and degradates of chlorpyrifos-methyl a nd that it specifies the residues to be measured for each commodity.

• Because of the use pattern for chlorpyrif os-methyl (on stored grains and inside grain storage facilities), residues in water are not anticipated. Therefore, a drinking water exposure analysis was not conducted and will not be required under registration review. If acute and chr onic points of departure are revised, the Agency will conduct a food-only dietar y assessment under registration review.

• The Agency anticipates updated occupa tional handler and occupational postapplication risk assessments will be needed for chlorpyrifos-methyl. The concentration of active ingredient ha s changed in the single remaining chlorpyrifos-methyl end-use product.

• The database is complete with the exception of the following studies, which the Agency anticipates requiring in orde r to conduct a complete human health

assessment:

4○ 870 Series acute toxicity studies (acute oral, acute dermal, acute inhalation, primary eye irritation, primary skin irritation). The dermal sensitization study will not be required.

○ 870.3250 Subchronic inhalation study

○ 870.7800 Immunotoxicity (rats)

○ Non-guideline study: Comparative cholinesterase assay (CCA): required for organophosphates incl uding chlorpyrifos-methyl.

○ 860.1500 Magnitude of the residue data were identified as outstanding in the 2000 TRED for as pirated grain fractions. Those data will be required in registration review.

• The recent cumulative risk assessmen t for the organophosphates includes a comprehensive assessment of OP exposu re and no risks of concern were identified for chlorpyrifos-methyl. Should the Agency determine that new information on chlorpyrifos-methyl is av ailable which could potentially impact

the cumulative risk assessment and resu lt in a risk of concern, the Agency will

revisit the cumulative risk assessment.

• Please refer to Chlorpyrifos Methyl. Human Health Assessment Scoping Document in Support of Registration Review, dated January 12, 2010, located in the chlorpyrifos-methyl docket, for a deta iled discussion of the anticipated human

health risk assessment needs.

Other Data Needs:

• OPPTS GLN 830.7050 UV/Visible Light Absorption – this study is a new data requirement under 40 CFR part 158 (Produc t Chemistry Data Requirements) for registration of a pesticid e (food and non-food uses). The Agency anticipates requiring this study to obtain basi c information a bout 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), EP A has developed the Endocrine Disruptor Screening Program (EDSP) to determine whet her 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 em ploys a two-tiered approach to making the statutorily required determinations. Tier 1 cons ists of a battery of 11 screening assays to identify the potential of a chemical substan ce to interact with th e estrogen, androgen, or thyroid (E, A, or T) hormona l 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. Ti er 2 testing is designed to identify any

5adverse endocrine related effects caused by th e substance, and esta blish a quantitative relationship between the dose a nd the E, A, or T effect.

Between October 2009 and February 2010, EPA issu ed 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 wa ter, residential activity, and certain postapplication agricultural s cenarios. This list should not be construed as a list of known or likely endocrine disruptors.

Chlorpyrifos-methyl is not among the group of 58 pesticide active ingredients on the

initial list to be screened under the EDSP. Under FFDCA sec. 408(p) the Agency must screen all pesticide chemicals. Accord ingly, EPA anticipates issuing future EDSP

orders/data call-ins for all Re gistration Review cases, incl uding those for which EPA has already opened a Registration Review docke t for a pesticide active ingredient.

For further information on the status of the ED SP, the policies and procedures, the list of 67 chemicals, the test guidelines and the Tier 1 screening battery, please visit our website: http://www.epa.gov/endo/.

Timeline :

EPA has created the following estimated ti meline for completion of the registration review for chlorpyrifos-methyl.

Registration Review for Chlorpyrifos-m ethyl – Projected Registration Review

Timeline

Activities Estimated Date
Opening the Docket Open Docket and Public Comment Period March 2010

Close Public Comment June 2010
Case Development Issue Final Work Plan (FWP) August 2010 Issue Data Call-in (DCI) April – June 2011

Data Submission April – June 2013 Open Public Comment Period for Preliminary Risk

Assessments October – December 2014

Close Public Comment Period January – March 2015

Registration Review Decision Open Public Comment Period for Proposed Registration

Review Decision April – June 2015

Close Public Comment Period July – September 2015 Final Registration Review Decision & Begin PostDecision Follow-up 2016

6Registration Review for Chlorpyrifos-m ethyl – Projected Registration Review

Timeline

Activities Estimated Date

Total (years) 6

Summary of Comments and Agency Responses :

The chlorpyrifos-methyl registration revi ew docket was open for a 60-day comment period beginning on March 31, 2010. During the comment period, multiple comments were received, which are summarized below. None of the comments received prompted a change in the work plan. This docum ent makes final the work plan for the chlorpyrifos-methyl regist ration review process.

Comments from Dow AgroScie nces [EPA-HQ-OPP-2010-0119-0012]

Comment 1: Dow AgroSciences (DAS) commen ted that the 1999 and 2002 NASS data supporting the chlorpyrifos-methyl preliminary wo rk plan is out of date in light of the 2004 and 2007 cancellations of chlorpyrifos-m ethyl sole active ingredient end-use products, and the 2004 registration of a chlo rpyrifos-methyl/deltamethrin combination product. Currently, the only re maining chlorpyrifos-methyl e nd-use product registered is for Storcide II, a combination product of chlo rpyrifos-methyl and deltamethrin registered during 2004 and with maximum chlorpyrifos-met hyl application rate of 3 mg ai/kg on grain. Additionally, chlorpyrifos-methyl is onl y registered in the U.S. for post-harvest use on barley, oats, rice, sorghum, and wheat, and there are no uses or tolerances of chlorpyrifos-methyl on corn.

Response 1: The Agency thanks DAS for their co mment, which may be considered in future chlorpyrifos-methyl assessments.

Comment 2: DAS cites EPA documents on the toxici ty of chlorpyrifos and chlorpyrifosmethyl. DAS states that the intrinsic t oxicological profiles an d characteristics for chlorpyrifos and chlorpyrifos-methyl have not changed, and DAS believes that the bridging approach suggested as a cour se of action by EPA in the 2003 and 2010 memoranda is relevant and appropriate fo r the current requests for the subchronic inhalation, immunotoxicity, and CCA studies. DAS requests that instead of requiring separate studies for each of these guidelines to be conducted with chlorpyrifos-methyl, EPA instead refer to studies already on file or about to be submitted to the Agency as part of the parallel Registration Review process for chlorpyrifos.

Response 2: The guideline immunotoxicity (870. 7800), subchronic inhalation (870.3465) and the non-guideline comparative cholinesterase studies currently remain as data gaps for chlorpyrifos methyl. EPA will consider the results as presented in the final reports of these study types conducted with the closely re lated organophosphate ch lorpyrifos (ethyl analog) when these studies are received as their final report. If these studies with chlorpyrifos (ethyl analog) are determined to satisfy the Agency’s standards for

7acceptable criteria, they will be considered fo r bridging to satisfying the requirements for chlorpyrifos-methyl.

Comments from Physicians Committee for Responsible Medicine (PCRM) [EPA-HQ-OPP-2010-0119-0014]

Comment 1: The chlorpyrifos-methyl human health scoping document, as well as the cited EPA 2003 and 2010 memoranda, state that bridging data from chlorpyrifos (CPY) would be considered for purposes of satisfyi ng chlorpyrifos-methyl data requirements. PCRM encourages DAS and the Agency to maximize this. The subchronic inhalation, immunotoxicity, and CCA studies can be waived using this approach.

Response 1: Please see the EPA response to DAS Comment 2 above.

Comment 2: For the 870 acute toxicity series (a cute oral, acute dermal, acute inhalation, primary eye irritation, primary skin irritation) PCRM challenges the Agency to look at a

number of validated and otherw ise scientifically appropriate nonanimal alternatives and strategies to fulfill CPM data requirements.

Response 2: Response 2: Reducing the use of animal-based testing is one of the Agency's ongoing goals as EPA is an activ e member of the Interagency Coordinating

Committee on the Validation of Alternative Methods (ICCVAM). EPA does currently accept the use of several test methods or tes ting approaches which result in the reduction of test animal usage, and the Agency will continue expanding the acceptance of such methods as they are approved by ICCVAM and associated internati onal organizations.

Comments from various university extensio n agents, crop specialists, and growers [EPA-HQ-OPP-2010-0119-0009, -0010, -0011, -0013]

Comment : Each of these comments stress the importance of the use chlorpyrifos-methyl on stored grain to protect against insect damage. Several comments mention that particularly in the southeastern U.S., alte rnative stored grain in secticides, including fumigants and diatomaceous earth, do not provide adequate protection.

Response: EPA thanks the commenters for their comments. The comments may be

considered in future chlor ypyrifos-methyl assessments.

Comment from Bayer CropScience [EPA-HQ-OPP-2010-0119-0015]

Comment: Bayer CropScience is the registrant for Storicide II, the sole remaining chlorpyrifos-methyl end-use product. This comment provides information on the usage

of Storicide II.

Response: EPA thanks Bayer CropScience for their comment, which may be considered in future chlorypyrifos-methyl assessments.

8Next Steps :

o The Agency plans to issue a DCI in mid 2011, requiring the chlorpyrifos-methyl studies needed to complete the human health risk assessment.

o The Agency will conduct a human health ri sk assessment for chlorpyrifos-methyl.

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