Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

BPA linked to thyroid hormone changes in pregnant women, newborns

04.10.2012
Bisphenol A (BPA), an estrogen-like compound that has drawn increased scrutiny in recent years, has been linked to changes in thyroid hormone levels in pregnant women and newborn boys, according to a new study by researchers at the University of California, Berkeley.

Normal thyroid function is essential to the healthy growth and cognitive development of fetuses and children. Yet, until this study, to be published Thursday, Oct. 4, in the journal Environmental Health Perspectives, little was known about the effects of BPA exposure on thyroid hormones in pregnant women and newborns.

The new findings add to growing health concerns about BPA, a chemical found in hard plastics, linings of canned food, dental sealants, and sales receipts on thermal paper, which is coated with a chemical that changes color when exposed to heat. In July, the U.S. Food and Drug Administration officially banned the chemical in baby bottles and cups, something the industry began doing voluntarily in recent years in response to consumer concerns about the potential risks of BPA.

The researchers analyzed BPA levels in the urine samples of 335 women during the second half of pregnancy, and thyroid hormone levels in blood samples taken from the mothers during pregnancy and from the newborns within a few days of birth. The participants were part of the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study led by Brenda Eskenazi, UC Berkeley professor of epidemiology and of maternal and child health.

The researchers found that for each doubling of BPA levels, there was an associated decrease of 0.13 micrograms per deciliter of total thyroxine (T4) in mothers during pregnancy, which suggests a hypothyroid effect. For newborn boys, each doubling of BPA levels linked to a 9.9 percent decrease in thyroid stimulating hormone (TSH), indicating a hyperthyroid effect.

"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," said study lead author Jonathan Chevrier, research epidemiologist at UC Berkeley's Center for Environmental Research and Children's Health (CERCH). "In addition, studies suggest that small changes in thyroid level, even if they're within normal limits, may still have a cognitive effect."

It was not clear why an association was not found among newborn girls, but animal studies may provide some clues. One study in neonatal rats found a similar hyperthyroidic effect in males, but not females. Another study found that female rats had higher levels of an enzyme important in metabolizing BPA when compared with their male counterparts. Whether that same relationship holds true for humans is not yet clear.

"In addition, 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 researchers pointed out that several studies in recent years have linked lower thyroid hormone levels to delays in cognitive and motor development in young children. Two years ago, the same group of UC Berkeley researchers also found links between PBDEs (polybrominated diphenyl ethers), a class of flame retardants, and changes in thyroid hormone levels.

They were confident that the BPA was acting on thyroid hormones independently from PBDEs, because levels of the two compounds were not correlated.

"There is good reason to be concerned about PBDEs and BPA, because both of these compounds are ubiquitous in our environment," said Harley. "More than 90 percent of women of reproductive age have detectable levels of BPA in their urine, and some 97 percent of U.S. residents have detectable levels of PBDEs in their blood. Until we learn more about the human health effects of these chemicals, it would make sense to be cautious and avoid exposure when possible, particularly for those who are pregnant."

Other co-authors of the study are Robert Gunier, Asa Bradman and Nina Holland from CERCH; and Antonia Calafat from the National Center for Environmental Health at the Centers for Disease Control and Prevention.

The U.S. Environmental Protection Agency, the National Institute for Environmental Health Sciences, the UC Institute for Mexico and the United States, and the UC Berkeley Center for Latino Policy Research provided support for this research.

Sarah Yang | EurekAlert!
Further information:
http://www.berkeley.edu

More articles from Health and Medicine:

nachricht The genes are not to blame
20.07.2018 | Technische Universität München

nachricht Targeting headaches and tumors with nano-submarines
20.07.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>