Identifying the cause of sediment toxicity in agricultural sediments: The role of pyrethroids and nine seldom-measured hydrophobic pesticides

► Monitoring fails to test for many agricultural pesticides used in any given area. ► Nine seldom-analyzed pesticides (e.g., abamectin) were tested for in sediments. ► One-quarter of the sediment samples were toxic to the amphipod, Hyalella azteca. ► The seldom-analyzed pesticides may have contributed to toxicity in a few samples. ► Pyrethroid insecticides were responsible for the vast majority of toxicity.