A study from Drexel University, in Philadelphia, has linked autism spectrum disorder with prenatal exposure to organochlorine chemicals. The researchers examined 1,144 children born in southern California between 2000 and 2003 with mothers that had enrolled in a state-sponsored prenatal screening program. Blood tests were taken during their second trimester of pregnancy, a critical time for neurodevelopment, to measure exposure to organochlorine chemicals, including polychlorinated biphenyls (PCB) and pesticides such as DDT. These compounds were banned from production in the U.S. in 1977, but remain in the environment. It’s well known that they can cross the placental barrier, impacting neurodevelopment in fetuses.
The researchers selected participants based on previous health diagnoses: 545 children with autism spectrum disorder and 181 with intellectual disabilities, plus 418 free of both issues as a control group. They found a 50 to 82 percent increased autism risk in children with the highest levels of four identified PCB compounds in utero, based on which ones were present.
“The results suggest that prenatal exposure to these chemicals above a certain level may influence neurodevelopment in adverse ways,” says Kristen Lyall, Sc.D., assistant professor in the university’s A.J. Drexel Autism Institute, promising further related studies.