Autistic Features Associated With Prenatal Exposure to Endocrine Disruptors

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Exposure to phthalates and flame retardants in the womb may contribute to autistic-like behaviors in offspring.

SAN DIEGO — Exposure during pregnancy to a combination of fire retardant chemicals and phthalate chemicals, which are present in the average home, may contribute to autistic-like behaviors in offspring, according to a Canadian study presented at ENDO 2015

The research only involved animal models but it points to potentially preventable causes of autism. Today, autism remains a diagnosis with enormous social costs and limited solutions. In addition, the rates appear to be steadily rising in North America.

“Our study is the first to evaluate the combined effect of two very common groups of endocrine disruptors, at doses relevant to human exposure, on the behavior of developing mammals concerning autistic features,” said lead study author Stephanie Degroote, MSc, a PhD student at the University of Sherbrooke in Quebec, Canada. 

“The clinical implications are major because these findings identify preventable risk factors for one of the major public health concerns for which we have no prevention and no cure. The exploding prevalence of autism over the years as well as the high sex ratio (5 boys for 1 girl) point to an important role of the environment, and according to our findings, to endocrine disruptors.”

Phthalates and brominated fire retardants are known endocrine disruptors. Degroote said the findings from her study show that it may be important to now consider the combined effect of these numerous substances, even when present at low doses that are considered safe for each of the chemicals.  

Past studies have suggested that exposure in the womb to either phthalates or flame retardants can affect mental and motor development and can provoke attention deficit. However, pregnant women are likely to come into contact with both chemicals simultaneously. They are common additives in many household plastic products, and flame retardants are on most furniture foam cushions.

Degroote and colleagues investigated what the combined effect of these endocrine disruptors would be on the developing brain in mammals. Their study was performed in rat pups, which were divided into three groups.

The first group included 28 pups whose pregnant mothers received low doses (by tube feeding) of a mixture of various phthalates and brominated flame retardants. The second group included 20 unexposed pups and the third group included 18 pups given valproic acid, a drug that induces autism in humans and autistic-like behavior in rats.

The investigators found that the rat pups whose pregnant mothers received the chemical mixture showed behavior similar to those seen in humans with autism spectrum disorders. These animals had reduced social interactions and increased hyperactive movements compared with unexposed pups.

In general, males were more affected than females and demonstrated less maternal bonding than their female counterparts. The third group, which served as a rat model of autism, had similar abnormal behaviors, including general developmental delays.

“The take-home message of my study is that the simultaneous exposure to several endocrine disruptors daily, even at low doses, can alter the development of the brain in utero and can lead to autistic features,” Degroote told Endocrinology Advisor.

“Women of child-bearing age should be aware of the risk of such exposition and consider ways to reduce their own exposure and the exposure of their children. With some changes in our habits, we can reduce our exposure and then reduce the risk for the future children to develop autistic features.”


  1. Degroote S et al. Abstract THR-290. Presented at: The Endocrine Society’s 97th Annual Meeting & Expo (ENDO 2015); March 5-8, 2015; San Diego.