BPA Chemical Affects Thyroid Glands of Pregnant Women and Babies

Exposure to the chemical Bisphenol- A disrupts thyroid functioning in pregnant women and subsequently their newborn, a new study says.

Thyroid hormones play a major role in regulating the metabolism of the body. Thyroid disease is a disorder of the thyroid gland. Both hyperthyroidism (too much thyroid hormone) and hypothyroidism (too little thyroid hormone) interfere with the normal function of every organ of the body and affects women's ability to conceive, pregnancy and health of the baby and the mother.

BPA is a chemical found in many plastic bottles and beverage cans. The controversial chemical has been linked to health issues like cancer, neurological issues, heart disease and reproductive problems.

The U.S. Food and Drug Administration (FDA) had recently issued a ban on the chemical in baby bottles and sippy cups. However, the chemical is still used as an internal coating for aluminum cans.

For the study, the researchers included 335 women, part of Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study. BPA levels in the urine samples of these participants were tested during pregnancy.  After birth, the level of thyroid hormones in mother and baby were measured.

High level of BPA was found disrupting the normal level of thyroid hormones in the body. For mothers, each doubling of BPA level was found bringing down the total thyroxine (T4) by 0.13 micrograms per deciliter and for newborn boys, a 9.9 decrease in thyroid stimulating hormone (TSH), showing hyperthyroid.

"Most of the women and newborns in our study had thyroid hormone levels within a normal range, but when we consider the impact of these results at a population level, we get concerned about a shift in the distribution that would affect those on the borderline," study lead author Jonathan Chevrier, research epidemiologist at UC Berkeley's Center for Environmental Research and Children's Health (CERCH), said in a statement.

"In addition, studies suggest that small changes in thyroid level, even if they're within normal limits, may still have a cognitive effect."

Such effects were not found among girl babies. According to the researchers BPA can have different effects based on genders.

"Studies in rodents are increasingly showing that BPA can have different effects in males and females, particularly in brain development and behavior," said the study's senior author, Kim Harley, adjunct associate professor of public health and associate director of CERCH.

The findings bring concern as disrupted thyroid levels are known to affect a healthy cognitive and motor development in young children.

Findings of the study have been published in the journal Environmental Health Perspectives.