Review of California's Risk-Assessment Process for Pesticides (2015) / Chapter Skim
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3 Risk-Assessment Practices for Pesticides
3 Risk-Assessment Practices for Pesticides
Pages 15-33
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From page 15... ...
, and DPR has asked the present committee to offer guidance on some of the ways in which those recommendations might be used to enhance its program. The Silver Book reaffirms most of the risk-assessment principles and concepts first elucidated in the National Research Council's 1983 report Risk Assessment in the Federal Government: Managing the Process (the "Red Book")
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From page 16... ...
DPR provided the committee with the guidance documents that it has developed (see Appendix B) and indicated that its guidance on uncertainty factors and calculation of reference values (DPR 2011)
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From page 17... ...
EPA efforts to adopt the the Silver Book's recommendations offer useful examples and practical guidance (see EPA 2014)
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18 FIGURE 3-1 A framework for risk-based decision-making that maximizes the utility of risk assessment. Source: NRC (2009, p.
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From page 19... ...
The proper course, if such circumstances arise, is to return to Phase I planning and the development of a more useful risk assessment. Stakeholder Involvement The Silver Book emphasizes the importance of stakeholder involvement in all phases of the decision framework (see box at the bottom of Figure 3-1)
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From page 20... ...
The Silver Book makes a number of recommendations for improving the selection and use of defaults, which DPR should consider in updating its guidance documents. For example, the agency should begin developing explicit defaults to use in place of missing defaults, such as defaults for human variation in susceptibility to cancer and for risks to susceptible subpopulations (during early life for other stages)
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From page 21... ...
As stressed in the Silver Book, problem formulation is critical for determining the level of complexity and quantification that would be needed for a cumulative risk assessment in light of the decision context. Lessons from Other National Research Council Reports National Research Council reports published after the Silver Book provide more detailed guidance on how to address issues raised in it.
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From page 22... ...
. CALIFORNIA'S RISK-ASSESSMENT PRACTICES The committee reviewed DPR's risk-assessment guidance documents and three examples of recent pesticide risk assessments -- of carbaryl, chloropicrin, and methyl iodide -- for the purpose of understanding the procedures and practices of DPR (see Appendix B for a list of documents reviewed)
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From page 23... ...
The documents reflect established practices and current trends in regulatory risk assessment as evidenced by several state-of-the-art approaches used to assess dose–response relationships and to model exposure. DPR uses several assets to develop and validate its risk assessments, primarily its collection of California-specific data on exposure, such as data obtained through its Pesticide Use Reporting program, Toxic Air Contaminants Program, and Pesticide Illness Surveillance Program.
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From page 24... ...
. Seven guidance documents on how DPR conducts its exposure assessments were provided (see Appendix B)
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From page 25... ...
DPR will have to continue to rely on national surveys and models, so it is important for it to stay current with scientific developments and workgroups for exposure modeling, such as the updated Dietary Exposure Evaluation Model -- Food Commodity Intake Database/Calendex model. For occupational scenarios, DPR relies primarily on the Pesticide Handler Exposure Database (PHED)
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From page 26... ...
The dates on DPR's risk-assessment guidance documents (see Appendix B) indicate that they have not been updated regularly and so do not reflect changes that might be necessary in response to recommendations of the Silver Book, EPA, or other resources.
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From page 27... ...
FIGURE 3-3 Comparison of reference values derived by EPA and DPR for the same active ingredients over three periods: before 1996, in 2004–2009, and in 2010–2014. The results in the upper panel compare chronic reference values for 39 active ingredients (RAAC 1996)
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From page 28... ...
Overall, DPR has generally estimated reference values within a factor of 5 of those established by EPA and rarely estimated toxicity greater than a factor of 2 above EPA. The magnitude of such differences lies within the normal bounds of uncertainty inherent in such assessments and raises the question of whether EPA's reference values and cancer potencies could be satisfactory for use by DPR in many risk assessments unless DPR has new toxicology studies that were not considered by EPA (which does not appear to be the case in the 11 recent examples)
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From page 29... ...
values and resulting judgments on the acceptability of the cancer risk are not obvious, because the processes used by EPA and Health Canada are not fully ex plained, but the differences reveal a lack of consensus and considerable uncertainty in this element of the risk assessment. The International Programme on Chemical Safety, the European Food Safety Authority, and the Australian Pesticides and Veterinary Medicines Authority used a different (threshold)
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From page 30... ...
Whether performing an independent risk assessment is the best use of DPR's resources to ensure occupational and public health protection is unclear. If the agencies are reviewing the same studies and using the same or similar guidelines, the hazard findings should be similar, and it might be possible for DPR to leverage the hazard identifications developed by EPA.
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From page 31... ...
If no new and compelling toxicology data have been generated since an EPA assessment was conducted and if there is no reason to believe that the EPA assessment is seriously flawed, DPR could rely on EPA's assessment to a greater extent. If the legislation allows, DPR should collaborate with EPA on its pesticide risk assessments and then rely on EPA's hazard identification, dose–response assessment, and derivation of reference values as a starting point for its own evaluations and focus its efforts on collecting Californiaspecific exposure data, which will help in tailoring the risk assessments to the state's needs.
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From page 32... ...
It might be useful for DPR to develop an overarching framework for considering and applying the various guidance documents on which it relies to ensure consistency between risk assessments and to aid new risk-assessment staff. DPR should update its guidance on defaults and begin developing explicit guidance on the inclusion of missing defaults, such as defaults for human variation in susceptibility to cancer and for risks to susceptible subpopulations (during early life and other stages)
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From page 33... ...
Medical Toxicology Branch, Department of Pesticide Regulation, California Environmental Protection Agency. November 14, 2012 [online]
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