SUBJECT: 

FROM: 

TO: 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

DATE: April 5, 2016 

Instructions for CErn enti on the Draft Biological Evaluations for Chlorpyrifos, 

Diazinon, and Mal ion 

Neil Anderson 

Branch Chief, Risk Management and Implementation Branch I 

Kelly Sherman \ J jn 0 I I 1\ r--____/ 

Branch Chief, ~~nVanHrnplementation Branch III 

Chlorpyrifos Registration Review Docket (EPA-HQ-OPP-2008-0850) 

Diazinon Registration Review Docket (EPA-HQ-OPP-2008-0351) 

Malathion Registration Review Docket (EPA-HQ-OPP-2009-0317) 

www.regulations.gov 

On March 31st, 2016, EPA is posting for public comment the draft biological evaluations (BEs) for 

chlorpyrifos, diazinon, and malathion in support of registration review. Registration review is EPA's 

periodic review of pesticide registrations to ensure that each pesticide continues to perform its intended 

function without unreasonable adverse effects. As part of the registration review process, the Agency 

has completed comprehensive draft BEs for all chlorpyrifos, diazinon, and malathion uses. These draft 

BEs represent the first nationwide assessments of these pesticides to federally endangered and 

threatened species (i.e., listed species) and designated critical habitat. The BEs also include analysis of 

impacts to candidate and proposed species and critical habitat proposed for listing under section 7 of 

the Endangered Species Act (ESA). The interim scientific methods used in these draft BEs were 

developed collaboratively with the U.S. Fish and Wildlife Service (USFWS) and the National Marine 

Fisheries Service (NMFS), hereafter referred to as the Services, based on recommendations from the 

April 2013 National Academy of Sciences (NAS) report titled "Assessing Risks to Endangered and 

Threatened Species from Pesticides". As part of this effort, the U.S. Department of Agriculture has 

provided information on crop production and pesticide uses and assistance with the use of the National 

Agricultural Statistics Service Cropland Data Layer to help define the footprint of agricultural use 

patterns. 

Through the registration review program, EPA is ensuring that each pesticide's registration is informed 

by the most current scientific data and methods. Furthermore, EPA is meeting its obligation under 

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Section 7 of the ESA by ensuring that each pesticide's registration is not likely to jeopardize the 

continued existence of any listed species or result in the destruction or adverse modification of 

designated critical habitat. More information about the endangered species program is available at: 

https://www.epa.gov/endangered-species/implementing-nas-report-recommendations-ecological-riskassessment -endangered -and 

The public comment period for the draft BEs will be open in April 2016. Because the file sizes of the 

draft BEs for chlorpyrifos, diazinon, and malathion exceed the docket system's file size limitation, the 

draft BEs will not be posted to the chlorpyrifos, diazinon, and malathion chemical dockets in 

www.regulations.gov. Instead, draft BEs for each ofthe three chemicals are posted on EPA's 

endangered species webpage. Comrnenters must post comments to each chemical's registration review 

docket at www.regulations.gov as detailed in Table 1. 

Table 1. Links to the Draft BEs and Where to Post Comments 

Chemical Link to the Draft BEs Where to Post Comments 

Chlorpyrifos https://www.epa.gov/endangered- EPA-HQ-OPP-2008-0850 

species/biological-evaluation-chapterschlorpyrifos 

Diazinon https :/ /www. epa. gov I endangered- EPA-HQ-OPP-2008-0351 

species/biological-evaluation-chaptersdiazinon 

Malathion https:/ /www.epa.gov/endangered- EPA-HQ-OPP-2009-0317 

species/biological-evaluation-chaptersmalathion 

Components of the Draft BEs 

Each draft BE for each of the three chemicals is grouped into four chapters. 

In Chapter 1 (the problem formulation), EPA outlines general information for each chemical (current 

registrations, use sites, application methods/rates, past risk mitigation, usage data, environmental fate 

characteristics) and its analysis plan. As part of its analysis plan, EPA outlines its approach for aquatic 

and terrestrial modeling to estimate exposure, the ecological effects data used to evaluate potential 

toxicity, and the various lines of evidence considered as part of its weight of evidence approach. Here, 

EPA also details the agency's approach for step 1 (making may affect [MA] or no effect [NE] 

determinations) and step 2 (making likely to adversely affect [LAA] or not likely to adversely affect 

[NLAA] determinations). 

In Chapter 2 (effects characterization), EPA reviews the existing toxicological database based on 

information submitted by pesticide applicants as well as studies from the open literature for each 

chemical and describes effects to various taxa, including effects to fish/aquatic amphibians, aquatic 

invertebrates, aquatic plants, birds, reptiles, terrestrial amphibians, mammals, terrestrial invertebrates, 

and terrestrial plants. Here EPA also identifies the thresholds used to evaluate direct and indirect 

effects to listed species and designated critical habitat. 

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In Chapter 3 (environmental transport and fate characterization), EPA describes the existing 

environmental fate and transport data, the model inputs used to estimate aquatic and terrestrial 

exposure, and the results of aquatic and terrestrial modeling including a characterization of available 

monitoring data for each chemical. 

In Chapter 4 (effects determinations), EPA makes NE, LAA, or NLAA determinations for each listed 

species and NE, LAA, and NLAA determinations for each designated critical habitat. There are 

approximately 1800 listed species and approximately 800 critical habitats for which effects 

determinations are concluded. 

Topics for Consideration and Comment 

When considering the 2013 NAS Report recommendations, EPA, FWS, and NMFS developed interim 

scientific methods to conduct national level pesticide risk assessments for listed species and their 

designated critical habitats. As the EPA and Services worked together to complete first drafts of the 

national-levellisted species assessments of chlorpyrifos, diazinon, and malathion, they built upon these 

interim methods. The three assessments describe a weight of evidence approach that integrates 

methods for assessing exposure and effects. Although many of these methods build upon existing 

models and approaches used by EPA, much of these methods are new to regulatory risk assessment 

and are considered draft at this time. The best available science has been used to inform the risk 

assessment and comments from the stakeholder community on how to improve on these interim 

scientific methods and approaches is encouraged. Public comments pertaining to following subject 

areas are of particular interest: 

• Identification of "best available" spatial data to represent potential pesticide use sites and 

species locations (Attachments 1-2 and 1-3) 

• Methods used to identify potential overlaps (and extent) of species locations and potential use 

sites and their applications in effects determinations made in Steps 1 and 2 (Attachment 1-6) 

• Estimation of exposure in various aquatic environments (bins) that have been regionally 

delineated and the parameterization of the bins and their relevance across the landscape 

(Attachment 3-1) 

• Evaluation of exposures in flowing water bodies and in non-freshwater habitats (e.g. , tidal 

pools, estuaries) (Attachment 3-1) 

• Evaluation of exposure to terrestrial organisms, including dietary and non-dietary routes of 

exposure (Attachment 1-7) 

• Evaluation of mosquito adulticide applications including potential exposure and impact on the 

aquatic and terrestrial environments (Appendix 3-3 for chlorpyrifos and malathion) 

• Use of species sensitivity distributions to evaluate effects (Attachment 1-5) 

• Characterization of toxicity data from registrant submitted toxicity data and scientific literature 

and utility of sublethal effects data (Attachments 1-4, and 1-22) 

• Use of mortality effects thresholds based on a chance of effects (i.e., l-in-a-million chance for 

direct effects and 10% chance of effect for indirect effects) (Attachment 1-4) 

• Methodology for assessing risks to plants (Attachment 1-21) 

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• Weight-of-evidence approach used, including the high, medium, and low weighting 

assignments to the various lines of evidence to evaluate risk and make effects determinations 

(Attachment 1-9) 

• "Qualitative" assessments for marine species and cave-dwelling terrestrial species. 

These draft biological evaluations for chlorpyrifos, diazinon and malathion represent the first nationallevellisted species assessments. It is expected that, over time, the methods used by the EPA and 

Services will evolve through experience and input from stakeholders and the public. In these drafts, 

many of the NAS recommendations are implemented where possible in the time since the report was 

published. Several of the recommendations will take time to develop sufficient methods and tools to 

implement for all listed species. One ofthose recommendations includes the use of probabilistic 

methods for assessing risks of pesticides to individuals and populations of listed species. To that end, a 

refined risk assessment is conducted for a subset oflisted birds using available tools (i.e., TIM and 

MCnest; Appendix 4-7). Also of great interest is the weight of evidence approach used for all listed 

species as implemented in the WoE tools. Although this approach integrated a great deal of 

information on several types of effects (i.e., survival, growth, reproduction, sensory, behavior), it relied 

heavily upon thresholds for making the effects determination. Based on this WoE analysis, few species 

considered in step 2 resulted in NLAA determinations. For some taxa, e.g. , plants that are not 

dependent upon animal pollinators, this conclusion seems to contradict the weight of evidence. 

Refinements to the WoE method and the thresholds and their roles in making effects determinations 

will be considered. 

How to Group Comments 

EPA anticipates a large volume of stakeholder comments. To help facilitate EPA's review of 

stakeholder comments, EPA is encouraging commenters to group their comments according to the 

following topics: 

1) Comments on the environmental models used in the draft BEs 

a. Comments addressing terrestrial models (ex. TIM/MCnest, TED tool) 

i. Model inputs 

b. Comments addressing aquatic models (ex. Pesticide in Water Calculator [PWC1

] , 

Downstream Dilution tool) 

1. Parameterization of the various aquatic bins 

ii. Model inputs 

iii. Spray drift parameterization, particularly for mosquito adulticide applications 

2) Comments on the approach used for Step 1 (making may affect [MA] or no effect [NE] 

determinations) 

3) Comments on the approach used for Step 2 (making likely to adversely affect [LAA] or not 

likely to adversely affect [NLAA] determinations) and the weight of evidence approach. 

4) Areas of consideration for further refinement 

a. Comments addressing aquatic exposure 

b. Comments addressing terrestrial exposure 

c. Comments addressing effects endpoints and derivation of thresholds 

1 The Pesticide in Water Calculator is a graphical user interface shell that facilitates the running of our Pesticide Root Zone 

Model (PRZM v 5.02) and Variable Volume Water Model (VVWM v 1.02). 

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5) Comments on the use/usage of chlorpyrifos, diazinon, or malathion 

6) Non-technical comments of a broader regulatory nature concerning the registration review 

program or the endangered species program 

7) Document errors and technical corrections 

Company A, for example, should submit one submission that contains several comments grouped in 

these categories. These categories are meant to be broad suggestions instead of firm guides. In 

general, commenters should keep chemical-specific comments separate from methodology-based 

comments that are applicable to all three chemicals. 

Points of Contact for Each Chemical 

For all questions related to this effort or concerning the registration reviews for chlorpyrifos, diazinon, 

and malathion, please direct questions to the chemical review manager identified in Table 2. 

T a bl e 2 . P es f ICI . d e C on t t ac s f or Chi orpyn os, 1azmon, an d M a a I th' IOn 

Registration Review Pesticide Docket ID Chemical Review Manager, 

Case Name and Number Number Telephone Number, Email Address 

Chlorpyrifos, case 1 00 EPA-HQ-OPP-2008-0850 Dana Friedman, 703-347-8827, 

friedman.dana@epa.gov 

Diazinon, case 238 EPA-HQ-OPP-2008-0351 Khue Nguyen, 703-347-0248, 

nguyen.khue@epa.gov 

Malathion, case 248 EPA-HQ-OPP-2009-0317 Steven Snyderman, 703-347-0249, 

snyderman.steven@epa.gov 

Anticipated Next Steps 

After reviewing comments received during the public comment period, EPA will issue revised final 

BEs, explain any changes, and respond to comments. For those species and designated critical habitats 

where registered uses of the pesticides are "likely to adversely affect" species and/or habitat, USFWS 

and NMFS will utilize the analyses and data from the biological evaluations in their final Biological 

Opinions for each of the three chemicals. Final BiOPs are scheduled to be completed in December 

2017. 

EPA will be holding a public webinar in April 2016 to provide a technical briefing of the 

analysis/interim methods used to make the effects determinations. This webinar will also provide 

guidance to stakeholders on how to navigate the BEs and address questions from the public. EPA will 

publish instructions shortly for this webinar. 

EPA will be holding a stakeholder workshop in 2016 to discuss the methods used in this interim 

approach and possibilities for refinement. EPA will publish additional information on this stakeholder 

workshop in spring 2016. 

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