As a fundamental principle of risk assessment schemes e.g. in the US and the EU, a tiered approach is proposed, using toxicity data from laboratory tests in the first tier as a starting point, moving on to higher tier tests with a more field realistic scenario if results of Tier I suggest that a risk cannot be excluded. Exposure assessment is an essential step in risk assessment schemes; conservative dietary and contact exposure estimates are used for calculation of pesticide exposure in first screening step and Tier I assessments. Depending on the application method (e.g. foliar uses or seed treatments/granules), on substance properties, (e.g. systemic vs. non-systemic pesticides), different potential routes of exposure may be relevant for honey bees, bumble bees and other non-Apis. In published literature often hazard identification studies prevail; especially for some more recently discussed routes of exposure, like dust exposure and exposure to guttation droplets, exposure assessment and risk characterization have yet been less specifically addressed. These somewhat �unusual� pathways of exposure are also more difficult to test in higher tier testing e.g. due to challenges of developing standard ways of applying dust in situ, in vitro, semi-field and field. Newer datasets from recent research e.g. on dusts and guttation allow a more detailed insight in potential pesticide exposure, allow a differentiation in more and less relevant routes and provide more information on the level of risk to bees and other pollinators. In the final risk assessment, all multiple lines of evidence need to be considered; data from incident monitoring used as a feedback for both risk assessment and management to ensure a negligible risk to bees in field-realistic conditions.

From hazard to risk: Dusts, guttation, and other routes of exposure and the risk to pollinators

248th National Meeting (2014)

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