Residential Proximity and Cumulative Risk Assessment of Agricultural Pesticide Applications in California

Abstract

BACKGROUND AND AIM: Pesticide exposure based on residential proximity to agricultural applications has been associated with adverse health outcomes including developmental neurotoxicity such as reduced IQ and autism spectrum disorder, adverse birth outcomes such as low birth weight and birth defects as well as increased risk of cancer. However, epidemiological studies have primarily assessed individual pesticides or groups of pesticides sharing a common mechanism of action. In reality, individuals living near agricultural pesticide applications are exposed to a complex mixture of pesticides impacting a broad range of potential health harms. Here we develop a toxicity index for pesticide mixtures based on multiple chronic toxicity endpoints, and identify residential areas at greatest risk of adverse health outcomes due to pesticide exposure. METHODS: Data for pesticide applications were downloaded from the California Pesticide Use Reporting program (PUR). Over 400 active ingredients were assessed for chronic toxicity endpoints including carcinogenicity, neurotoxicity, endocrine disruption, thyroid toxicity and respiratory toxicity based on classifications from authoritative bodies including the EPA, IARC, and EFSA. We developed a toxicity index for each active ingredient based on the severity of the health outcome, the strength of the association, the reliability of the data source and the NOAEL if available. We then combined the toxicity index with application rates for all pesticides applied within a square mile. RESULTS:Pesticides with the greatest toxicity index include active ingredients previously associated with adverse health outcomes including organophosphates and carbamates. Other pesticides with high toxicity indices include neonicotinoids, pyrethroids and triazole fungicides. Residential areas of high risk of potential adverse health effects due to pesticide exposure from nearby agricultural applications were identified. CONCLUSIONS:Using the pesticide toxicity index and application rates in combination with residential proximity agricultural applications can help identify and prioritize high risk areas for future pesticide policy actions to best protect public health. KEYWORDS: pesticides, cumulative risk assessment, residential proximity