The California Department of Pesticide Regulation (DPR) is responsible for scientifically evaluating risks to non-target organisms from the use of pesticides in the state. DPR’s primary means of mitigating ecological risks is by evaluating pesticide labels and regulating the pesticides approved for use in California. This presentation discusses case studies of pesticide labeling that reduce risks to honey bees and aquatic invertebrates by limiting potential exposure. When evaluating label language for ecotoxicological risk, DPR first quantifies a pesticide’s toxicity to several surrogate species representing various vertebrate and invertebrate taxa using data from controlled studies performed by contract laboratories. DPR then estimates environmental concentrations of the pesticide using models that consider physicochemical properties, California-specific climate, and label uses and application rates. Pesticides with minimal or mitigated risks to fauna may be registered for the specific uses defined by the label; pesticides with unmitigated risks to fauna are denied registration. In the honey bee case study, label mitigation for a non-systemic, synthetic insecticide included prohibiting applications to crops in bloom, reducing the application rate, and increasing the reapplication interval. In the aquatic invertebrate case study, label mitigation for a synthetic insecticide included increasing the spray droplet size and the spray drift buffer between the application site and bodies of water. In both cases, non-target pesticide exposure was measurably reduced.
