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Member Research & Reports

Chemicals Banned Decades Ago Linked to Increased Autism Risk Today, Drexel Autism Researcher Finds

A new Drexel University Dornsife School of Public Health study published in Environmental Health Perspectives found that children born after being exposed to the highest levels of organochlorine chemicals during their mother’s pregnancy were roughly 80 percent more likely to be diagnosed with autism when compared to individuals with the very lowest levels of these chemicals as well as those who were completely unexposed.

Now an assistant professor at Drexel  in the A.J. Drexel Autism Institute’s Modifiable Risk Factors Program, the study’s lead author Dr. Kristen Lyall, was with the California Department of Public Health when she began the work. She teamed with researchers from the department, including Dr. Gayle Windham and Dr. Martin Kharrazi,  members of the Kaiser Permanente Division of Research (which includes the study’s principal investigator, Dr. Lisa Croen), as well as an expert on measuring organochlorine chemicals, Dr. Andreas Sjodin,  of the Division of Laboratory Sciences of the National Center for Environmental Health.

The team looked at a population sample of 1,144 children born in Southern California between 2000 and 2003. Data was accrued from mothers who had enrolled in California’s Expanded Alphafetoprotein Prenatal Screening Program, which is dedicated to detecting birth defects during pregnancy.

Participants’ children were separated into three groups: 545 who were diagnosed with autism spectrum disorder, 181 with intellectual disabilities but no autism diagnosis, and 418 with a diagnosis of neither.

Blood tests taken from the second trimester of the children’s mothers were used to determine the level of exposure to two different classes of organochlorine chemicals: Polychlorinated biphenyls (PCBs, which were used as lubricants, coolants and insulators in consumer and electrical products) and organochlorine pesticides (OCPs, which include chemicals like DDT).

It was determined that two compounds in particular — PCB 138/158 and PCB 153 — stood out as being significantly linked with autism risk. Children with the highest in utero levels (exposure during their mother’s pregnancy) of these two forms of PCBs were between 79 and 82 percent more likely to have an autism diagnosis than those found to be exposed to the lowest levels. High levels of two other compounds, PCB 170 and PCB 180, were also associated with children being approximately 50 percent more likely to be diagnosed — again, this is relative to children with the lowest prenatal exposure to these PCBs.

None of the OCPs appeared to show an association with higher autism diagnosis risk.

“The results suggest that prenatal exposure to these chemicals above a certain level may influence neurodevelopment in adverse ways,” Dr. Lyall said.

Drexel Press Release: