Researchers have found that increased exposure to thyroid-disrupting toxins during pregnancy could subsequently lead to increased risk of brain development disorders in children.

Exposure of pregnant women to common thyroid-hormone-disrupting toxins may be linked to the increased incidence of child brain development disorders, researchers have found. Numerous, common chemicals can interfere with normal thyroid hormone actions, which are essential for normal brain development in foetuses and young children, they say.

"We have reviewed the documented exposures of pregnant women and children to mixtures of thyroid-hormone-disrupting chemicals and propose that the data sets provide a plausible link to the recent increased incidence of neurodevelopmental conditions," said study co-author Barbara Demeneix, Professor at the Universite Paris-Sorbonne. Many of the identified endocrine-disrupting chemicals (EDCs), which include pesticides and substances used in manufacturing a multitude of products, have been reported to interfere with thyroid hormone function, the researchers said.

With maternal thyroid hormones (TH) essential for normal brain development of children, the researchers also said that previous human studies have indicated that even moderate disruption to TH function in pregnant women may affect cognitive development and increase the risk of brain developmental disorders in their children. For the study, published in the journal Endocrine Connections, researchers examined published evidence of the wide variety and high number of EDCs, from pesticides to chemicals used in the manufacture of drugs, cosmetics, furniture and plastics, that can all interfere with TH.

The research further highlights that complex mixtures of these thyroid-disrupting chemicals are present in all humans, including children and pregnant women. These findings indicate that exposures of pregnant women and children to thyroid-disrupting chemicals in the environment pose real risks for child development and health, and underline the need for a more targeted public health intervention strategy, it says.