Autism Linked to Pre Natal Exposure to Chemicals Banned in the 1970s

23 Aug 2016 --- Pregnant women exposed to certain chemicals banned in the 1970s, are more likely to give birth to children with autism spectrum disorder, a new study from Drexel University has shown.

Although the production of organochlorine chemicals was banned in the United States in 1977, the compounds can remain in the environment and become absorbed in the fat of animals that humans eat, leading to exposure in the modern day.

Kristen Lyall, ScD, assistant professor in Drexel University's A.J. Drexel Autism Institute, and her collaborators, decided to look at organochlorine chemicals during pregnancy since they can cross through the placenta and affect the fetus' neurodevelopment.

"There's a fair amount of research examining exposure to these chemicals during pregnancy in association with other outcomes, for example, birth weight, but little research on autism, specifically," said Lyall.

"To examine the role of environmental exposures in risk of autism, it is important that samples are collected during time frames with evidence for susceptibility for autism, termed 'critical windows' in neurodevelopment. Fetal development is one of those critical windows."

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 the organochlorine chemicals.

The research showed that children born after being exposed to the highest levels of certain compounds of the 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 and those who were completely unexposed.

"The results suggest that prenatal exposure to these chemicals above a certain level may influence neurodevelopment in adverse ways," stated Lyall.

The results of this study are the first to suggest these compounds may increase risk of development of autism, and Lyall and her colleagues are looking to continue researching the area.

"We are definitely doing more research to build on this,” Lyall said, “including work examining genetics, as well as mixtures of chemicals. This investigation draws from a rich dataset and we need more studies like this in autism research."