Occurrence and distribution of sediment-associated insecticides in urban waterways in the Pearl River Delta, China

► Both Legacy and currently used insecticides were detected in sediment in urban waterways in the Pearl River Delta (PRD), China. ► Cypermethrin, a pyrethroid, was the most abundant insecticide detected. ► Transition in application pattern and elevated urbanization increased accumulation of pyrethroids in sediment and made them the predominate insecticides in the PRD urban waterways.