Travis S. Schmidt Peter C. Van Metre Barbara Mahler Mark W. Sandstrom Lisa H. Nowell Daren M. Carlisle Patrick W. Moran Janet L. Miller 2020 <p><span>Insecticides in streams are increasingly a global concern, yet information on safe concentrations for aquatic ecosystems is sparse. In a 30-day mesocosm experiment exposing native benthic aquatic invertebrates to the common insecticide fipronil and four degradates, fipronil compounds caused altered emergence and trophic cascades. Effect concentrations eliciting a 50% response (EC</span>₅₀<span>) were developed for fipronil and its sulfide, sulfone, and desulfinyl degradates; taxa were insensitive to fipronil amide. Hazard concentrations for 5% of affected species derived from up to 15 mesocosm EC</span>₅₀<span>&nbsp;values were used to convert fipronil compound concentrations in field samples to the sum of toxic units (∑TU</span>_Fipronils<span>). Mean ∑TU</span>_Fipronils<span>&nbsp;exceeded 1 (indicating toxicity) in 16% of streams sampled from five regional studies. The Species at Risk invertebrate metric was negatively associated with ∑TU</span>_Fipronils<span>&nbsp;in four of five regions sampled. This ecological risk assessment indicates that low concentrations of fipronil compounds degrade stream communities in multiple regions of the United States.</span></p> application/pdf 10.1126/sciadv.abc1299 en American Association for the Advancement of Science Common insecticide disrupts aquatic communities: A mesocosm-to-field ecological risk assessment of fipronil and its degradates in U.S. streams article