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Two lines of evidence suggest that endocrine disruption may be a factor in autism spectrum disorders (ASDs). First, the observation that males may be four times as likely to be diagnosed with ASDs as females suggests hormonal involvement.1 Second, adrenal, gonadal, and thyroid hormones play an important role in fetal neurodevelopment,2,3,4 and any chemical that interferes with the actions of these hormones therefore has the potential to disrupt brain development. By analyzing samples and data from a prospective birth cohort study, a team of U.S. and Canadian researchers have identified a handful of endocrine-disrupting chemicals (EDCs) they believe merit further study as possible contributors to ASDs.5

ASDs encompass a complex set of disorders that have been associated with more than 800 potential genetic risk factors, says Isaac Pessah, associate dean of research and graduate education at the University of California, Davis, who was not involved with the study. In March 2014 the Centers for Disease Control and Prevention revised its estimates of the number of children with ASDs to 1 in 68, up from 1 in 88.6

“We suspect that environment and genetics interact on the fetus prenatally or very early in life to increase or decrease the risk of autism,” says study author Joseph Braun, an epidemiologist at Brown University School of Public Health. Given the importance of identifying environmental risk factors for the conditions, he says surprisingly little research has investigated the role that exposure to EDCs may play in ASDs.

The new study analyzed data for 175 women participating in the Health Outcomes and Measures of the Environment (HOME) Study. The cohort includes women who lived in the Cincinnati, Ohio, metropolitan area when they were pregnant between 2003 and 2006. The women provided blood and urine samples during pregnancy, which were analyzed for 52 endocrine-disrupting chemicals. At ages 4 and 5 years old, the children were rated by their mothers using the Social Responsiveness Scale (SRS), a tool that assesses behaviors typically related to ASDs.