OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

RE: Meeting between Dow AgroSciences (DAS) and EPA to Discuss DAS’ Proposal 

for Developing a Chlorpyrifos Higher Tier Ecological Risk Assessment

List of Documents

1. Meeting Summary Page 1

2. Meeting Sign in Sheet Page 2

3. DAS Talking Points for the Meeting Page 3

Meeting Summary

On Monday, December 12, 2011, EPA’s Office of Pesticide Programs met with Dow 

AgroSciences (DAS) to discuss their proposal for developing a chlorpyrifos higher tier 

ecological risk assessment. DAS is planning to convene its own panel to generate a higher-tier 

ecological risk assessment in the next 1-2 years and wanted to discuss this proposal with the 

Agency. Areas discussed included fate and transport of chlorpyrifos and the chlorpyrifos oxon, 

endangered species, modeling of exposures in aquatic and terrestrial systems, and effects in 

aquatic and terrestrial systems. DAS will also be submitting to the Agency a bibliography of 

published papers since 2000 dealing with chlorpyrifos.
Name 

J~L Wo 

Dow AgroSciences and EPA 

Chlorpyrifos Ecorisk Meeting 

December 12,2011 

Affiliation Phone Number E-mail 

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Talking points for the meeting of Dow AgroSciences 

Chlorpyrifos Panel with EPA on December 12, 2011 

Participants in the Meeting 

Prof. John P. Giesy, Chair, DAS Chlorpyrifos Panel 

Prof. Keith Solomon, Co-Chair, DAS Chlorpyrifos Panel 

Dr. Nick Poletika, Science Leader, DAS 

Dr. Darin Lickfeldt, Regulatory Manager, DAS 

1 Purpose of the meeting 

Dow AgroSciences will be using our own panel over the next 1-2 years to generate a 

higher-tier risk assessment much like we did for the Human Health risk assessment 

submitted in October 2011. We want to be open and transparent throughout this 

process to make sure the areas of greatest concern with regards to Chlorpyrifos are 

addressed by our analysis. Therefore, we need a better understanding of areas of 

greatest concern or areas that need better definition. We hope to get a better 

understanding of where data gaps exist from EFEDs perspective. What additional 

data/analysis' would be useful to have 1-2 years from now? 

Members of the panel include: 

Prof. John P. Giesy, Ph.D., FRSC, Prof. & Canada Research Chair in Environmental 

Toxicology 

University of Saskatchewan 

Prof. Keith R. Solomon, Ph.D., Emeritus Prof. 

University of Guelph 

Dr. Jeff Giddings, Ph.D. 

Compliance Services, Inc. 

Dr. Dwayne Moore, Ph.D. 

lntrinsik Environmental Sciences, Inc 

Other expert(s) will be added as needed and as issues are identified at this meeting and 

when the data are assembled. 

Page 1 of 4 
2 Questions of clarification from the problem formulation 

2.1 Mode(s) of action 

1. How will EPA incorporate metabolic activation of chlorpyrifos into the conceptual 

model for exposure and/or effects? 

2. Is EPA considering synergism of chlorpyrifos in its conceptual model of effects? 

3. How will EPA integrate other potential effects such as those modulated by the 

endocrine system into the conceptual model of effects? 

2.2 Fate and transport of chlorpyrifos 

1. How will EPA consider movement to and accumulation in distant locations in the 

conceptual model for exposures? 

2.3 Fate, transport, and toxicity of chlorpyrifos oxon and other 

products of degradation 

1. How is EPA planning to consider fate of chlorpyrifos oxon in environmental 

media? 

2. How will exposures to the oxon be incorporated into the conceptual model of 

exposures? 

3. How does the EPA plan to consider degradates such as trichlorophenol? 

2.4 Bioconcentration and bioaccumulation 

1 . What will the approach be for aquatic systems? 

2. What will the approach be for terrestrial systems? 

2.5 Modeling of exposures in aquatic and terrestrial systems 

1. Will EPA model both maximum and typical application rates and intervals? What 

use patterns are of particular interest to EPA in their assessment? 

2. Is EPA planning to refine the conceptual model(s) for direct and indirect 

exposures in aquatic systems? 

3. Is EPA planning to refine the conceptual model for exposures of terrestrial 

organisms? 

4. Is EPA planning on conducting food web modeling for assessing risk to avian 

predators, such as through relay toxicity? 

5. How will EPA refine the conceptual model for exposure of birds to the oxon? 

6. Will EPA consider using chlorpyrifos-specific nomograms instead of the standard 

Kenaga nomograms? 

7. Will EPA consider using more advanced methods than the current LD50s/ff 

method for characterizing exposures to granular formulations in birds? 

8. For the flowable formulation, will EPA conduct higher tier assessments for birds 

and mammals (i.e., beyond standard T-REX analysis)? 

9. Will herps, such as frogs and salamanders be included in the terrestrial 

assessment? 

10. Will EPA model the concentrations of chlorpyrifos in flowing water, estuaries, and 

other water bodies where exposure will differ from the standard pond scenario? 

11. How is EPA planning to model the exposure of sediment-dwelling organisms? 

Page 2 of 4 

t 
2.6 Effects in aquatic systems 

1. Is EPA planning to refine the conceptual model(s) for direct and indirect effects in 

aquatic systems? 

2. How will data from microcosms, mesocosms and field studies be incorporated 

into the characterization of effects? 

3. How will EPA assess risk to aquatic vascular plants if toxicity data are 

unavailable? 

4. How will bioavailability of chlorpyrifos in different kinds of sediment be taken into 

account in assessing effects on benthic organisms? 

5. When results of toxicity tests are available from multiple studies on the same 

species, possibly including both GLP and non-GLP studies, what criteria will EPA 

use in selecting endpoints for the risk assessment (e.g., lowest reported value, 

geometric mean, ecological relevance, reliability)? 

6. Is EPA planning to use population models to estimate risk to sensitive aquatic 

species? 

2. 7 Effects in terrestrial systems 

1. Will EPA be refining the conceptual model(s) for direct and effects? 

2. How will EPA incorporate incident data and field studies into the conceptual 

model for effects? 

3. When results of toxicity test are available from both GLP and non-GLP studies on 

the same species and endpoint, will EPA give preference to the GLP study 

results? 

4. Can EPA provide insight into how the pollinators portion of the assessment will 

be conducted? 

5. Are effects on plants a concern and if so how will they be evaluated? 

2.8 Endangered species 

1. Will EPA be issuing guidance on the conduct of National Endangered Species 

Assessments in the near future so that we can better understand their planned 

approach? 

2. How will information provided by registrants about the location, biology, and 

ecology of T&E species be incorporated into EPA's ES assessment? 

3. To what level of resolution will spatial modeling of exposures be considered? 

4. How will habitat preference be considered (e.g., if the T&E species only found at 

higher elevations and thus not susceptible to runoff exposure)? 

5. How will sensitivity be considered (e.g., T&E plants likely not be at risk for 

chlorpyrifos even in close proximity)? Said another way, will risk to T&E species 

be estimated using toxicity data for closely related surrogate species, or will only 

the most sensitive species in each major taxonomic group (e.g., fish, aquatic 

invertebrates, birds, mammals) be used? 

6. Will indirect effects be assessed in the context of the specific food and habitat 

requirements of individual T&E species? 

7. Does EPA intend to work with registrants to develop mitigations to reduce risk to 

T&E species before requesting consultation with the Services? 

Page 3 of 4 
2.9 Concentrations in aquatic systems 

1. How will EPA be updating the data on concentrations in aquatic systems from the 

situation in 2007? 

2. Does the EPA plan to use data on concentrations measured in targeted 

monitoring programs from states such as CA and the Pacific Northwest? 

3. If concentrations measured in targeted monitoring programs indicate that the 

standard aquatic exposure model overestimates chlorpyrifos concentrations, will 

the monitoring data be used to support more realistic assumptions in the model? 

3 Published papers for 2000-present 

1. The panel will describe for EPA the database of papers that has been developed. 

The panel is willing to share all of this information and our summaries of the 

information contained in the papers with EPA. 

Page 4 of 4