BACKGROUND: Directive 91/414/EEC envisages that the systemic properties of active substances, if any, are taken into account in evaluating the risk posed to the environment by plant protection products. Among others, honey bees may be exposed to substances via this route, which may pose problems when substances with high toxicity are ingested through pollen or nectar. The guidance documents in support of the risk assessment to bees within the framework of Directive 91/414/EEC do not provide detailed technical guidance on how to proceed in a risk assessment for substances with systemic properties.
RESULTS: A stepwise approach aiming specifically to assess the risk posed by non-sprayed systemic substances to bees is therefore proposed. This approach first identifies substances with systemic properties, which should be quantified in plant material as pollen and nectar. Exposure estimates calculated for different categories of bees (e.g. foraging bees), based on expected concentrations of the product in pollen or nectar, may be compared with several toxicity endpoints for acute or chronic effects on adults and/or larvae with a toxicity/exposure ratio, which is a measurement of potential risks.
CONCLUSION: Such a ratio is proposed to be used as a trigger for any further refined assessment that would focus on the measurement of effects at the colony level. Copyright © 2007 Society of Chemical Industry