The U.S. Environmental Protection Agency, Health Canada's Pest Management Regulatory Agency, and the California Department of Pesticide Regulation developed a tiered process for evaluating potential adverse effects on pollinating bees from exposure to pesticides.  If exposure is considered likely, then Tier I modeled exposure estimates or conservative default values are compared against laboratory-based toxicity estimates for individual bees.  Empirical data on residues in pollen and nectar may be used to refine exposure estimates.  The risk assessor calculates risk quotients (i.e., measures of exposure divided by the relevant toxicity endpoint), which are then compared to a level of concern.  Information from open literature, unpublished registrant studies, and bee kill incidents may further characterize potential risks.  Tier II includes toxicity studies conducted at the colony level either within a tunnel enclosure or in an open field using colonies provided with spiked diets at known concentrations.  If further refinement is necessary, Tier III field studies are conducted under real-world exposure scenarios to address specific uncertainties identified in lower-tier studies.  Tiers II and III toxicity studies, in combination with residue studies of pollen and nectar, may further characterize potential risk(s).  Exposure and toxicity data focus on the honey bee (Apis mellifera) as a surrogate for all pollinating bees, but when available, data on other non-Apis bees may be included in the risk assessment.  The overall process for assessing potential risks to bees depends on multiple lines of evidence, and risk management options may be considered at any tier in the process.

Tiered risk assessment process to evaluate potential adverse effects to pollinating bees from exposure to pesticides

248th National Meeting (2014)

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