Prenatal exposure to pesticide ingredient piperonyl butoxide and childhood cough in an urban cohort

► The health impact of residential pyrethroid exposure has not been evaluated fully. ► We examined permethrin and a common pyrethroid synergist piperonyl butoxide (PBO). ► Permethrin and PBO were measured in air samples prenatally and at age 5-6 years. ► Exposure to prenatal PBO only was associated with increased odds of cough. ► In utero exposure to PBO or pyrethroids may lead to cough in early childhood.