Neonicotinoid Insecticides from a Marine Perspective: Acute and Chronic Copepod Testing and Derivation of Environmental Quality Standards

Neonicotinoid insecticides have become of global concern for the aquatic environment. Harpacticoid copepods are among organisms most sensitive to neonicotinoids. We exposed brackish copepod Nitocra spinipes 4 neonicotinoid (clothianidin, imidacloprid, thiacloprid, and thiamethoxam) investigate acute toxicity on adults (96-h exposure) effects larval development (7-d exposure). used these results in combination with publicly available ecotoxicity data derive environmental quality standards (EQS). These EQS were ultimately a single-substance mixture risk assessment Belgian part North Sea. Acute testing revealed that immobilization is more endpoint than mortality, 96-h median effect concentration (EC50) values 6.9, 7.2, 25, 120 µg L-1 clothianidin, thiamethoxam, respectively. In addition, tests resulted 7-d no-observed-effect concentrations (NOECs) 2.5, 2.7, 4.2, >99 µg L-1 The derived saltwater annual average (AA-)EQS 0.05, 0.0048, 0.002, 0.016 µg L-1 Finally, characterization some exceedances AA-EQS harbors imidacloprid (number exceedances, n = 2/4), thiacloprid (n = 1/4), thiamethoxam neonicotinoids (n = 4/4), but not at open sea. At sea site, toxic unit sums relative 0.72 0.22, suggesting no risk, albeit relatively small margin safety. Including short-term EC10 (96-h) N. derivation led refinement clothianidin their use because one overarching goals definition protect species population level. Environ Toxicol Chem 2021;40:1353-1367. © 2021 SETAC.