ScienceDaily (Feb. 10, 2011) — When the EPA phased out the widespread residential use of chlorpyrifos and other organophosphorus (OP) insecticides in 2000-2001 because of risks to child neurodevelopment, these compounds were largely replaced with pyrethroid insecticides. But the safety of these replacement insecticides remained unclear, as they had never been evaluated for long-term neurotoxic effects after low-level exposure. In the first study to examine the effects of these compounds on humans and the first evaluation of their potential toxicity to the developing fetal brain, scientists of the Columbia Center for Children's Environmental Health at Columbia University's Mailman School of Public Health found a significant association between piperonyl butoxide (PBO), a common additive in pyrethroid formulations, measured in personal air collected during the third trimester of pregnancy, and delayed mental development at 36 months.
PBO was detected in the majority of personal air samples (75%). While the results demonstrate that a significant prenatal exposure to permethrin in personal air and/or plasma was not associated with performance scores for the Bayley Mental Developmental Index or the Psychomotor Developmental Index at 36 months, children who were more highly exposed to PBO in personal air samples (≥4.34 ng/m3) scored 3.9 points lower on the Mental Developmental Index than those with lower exposures.
"This drop in IQ points is similar to that observed in response to lead exposure," said Megan Horton of the Mailman School of Public Health and lead researcher. "While perhaps not impacting an individual's overall function, it is educationally meaningful and could shift the distribution of children in the society who would be in need of early intervention services."