Flame retardant chemicals such as polybrominated diphenyl ethers, or PBDEs, can be found in many household products which means exposure to them is almost unavoidable. Studies conducted at University of California at Riverside showed adult female mice exposed to PBDEs pass those chemicals to their offspring which can result in autism-like changes in the brain.
PBDEs are used in the making of upholstery, carpets, curtains and even baby products. They can migrate out of products through contact and be inhaled by breathing in dust particles. They have been found around the globe in air, water and soil samples, as well as in food products, animal and human tissue and breast milk.
When the neuroendocrine-disrupting chemicals were passed to the baby mice they displayed diminished short-term social-recognition ability and lessened long-term social memory. Researchers also observed exaggerated “marble burying” behavior, which is a repetitive behavior similar to compulsive human behavior which is a core symptom of autism spectrum disorder (ASD).
"Our data support a link between maternal toxicant exposures and abnormal social and repetitive behavior in mice offspring that is relevant to ASD," said professor Margarita Curras-Collazo. "Humans mostly rely on faces to recognize people and most autistics show deficits in face-identity processing. Mice, on the other hand, rely on smell for social recognition. The female offspring of mother mice exposed to PBDEs showed olfactory deficits that dampened their ability to recognize other mice. In effect, these offspring do not distinguish new mice from familiar ones. Humans with ASD also show abnormal olfactory ability."
The young mice acquired the PBDEs, which were given orally to the adult female mice, through blood during gestation and through mother’s milk during lactation. Researchers measured social and repetitive behavior and also examined the brains of the mice. They found oxytocin and other pro-social genes had undergone changes. That suggested to researchers that PBDEs have the ability to target specific brain systems during development which can cause abnormalities.
"This shows that developmental PBDE exposure produces ASD-relevant neurochemical, olfactory, and social behavioral traits in adult female offspring that may result from early neurodevelopmental reprogramming within central social and memory neural networks," said fellow researcher Elena Kozlova.
Researchers did not observe any changes to the adult mice that were exposed. But the fact those chemicals were able to affect the brains of young mice as they develop convinced them more work needs to be done to understand the impact of PBDEs on human health.