Panel assesses health impacts of chemical in plastics
Baby bottles made without bisphenol A are now on the market. Here six-month-old Jack drinks from a brand that is BPA-free.
Photo by Terri Leith
In what has become a continuing discussion of the danger to human health posed by bisphenol A, a chemical that mimics estrogen and is found in many plastic products, Dr. John Vandenbergh speaks for those without a voice, the unborn and the newborn.
Vandenbergh, professor emeritus in the Department of Zoology (now Biology) in the College of Agriculture and Life Sciences, served in 2007 and 2008 on a National Institutes of Health (NIH) National Toxicology Program Expert Panel charged with assessing the human health impact of bisphenol A, also known as BPA.
Bisphenol A is ubiquitous: Approximately 7 billion tons are produced around the world annually, Vandenbergh said. It is used to make polycarbonate plastic, which, in turn, is used in a wide range of consumer products, from CDs to eyeglass lenses to the liners of the cans in which food is packaged and other food containers.
That humans are exposed to BPA in their everyday lives is beyond dispute. In a recent study of approximately 2,500 Americans, 93 percent had BPA in their urine. The result of that exposure continues to be a matter for scientific inquiry and possible government regulation.
In August 2008, the federal Food and Drug Administration, which has the power to regulate BPA, released a report saying it is not necessary to regulate use of the chemical. Yet the next month, a study published in the Journal of the American Medical Association suggested a link between BPA and heart disease and diabetes in adults.
The National Toxicology Program committee on which Vandenbergh served reviewed much of the scientific literature on bisphenol A and came to the conclusion that for adults, there is a slight concern that the amounts of BPA to which we are typically exposed will have negative health impacts.
“If you’re an adult, you consume BPA; you metabolize it; it’s in your urine within 2 hours,” Vandenbergh explained.
But it’s a different story for fetuses, infants and children, and that’s where Vandenbergh’s expertise comes into play. The panel found reason for “some concern” that bisphenol A could negatively affect the health of people exposed to BPA either in the womb or as newborns. But negative health impacts – BPA can affect the brain and behavior – may not show up until adulthood.
“Your liver and mine are working pretty hard to break down these products, but if you are a newborn baby or a fetus, you don’t have the mechanism to break down this product; therefore, the dose you’re exposed to is higher,” Vandenbergh explained.
During his career, much of Vandenbergh’s work focused on better understanding the factors that influence the development of an animal while that animal is a fetus. For example, working with mice, Vandenbergh showed that the position of a mouse fetus in relation to other fetuses in the womb has an impact on how the adult animal develops.
“I was there (on the National Toxicology Program panel) because we had done quite a bit of work on the behavioral consequences of BPA exposure and have published two articles with graduate students on that topic, basically finding there was an increase in what’s called anxiety behavior in animals (exposed to BPA),” Vandenbergh said.
In experiments with mice, Vandenbergh found that a fetus need not be exposed directly to BPA to be affected by the chemical.
“The important thing is the exposure to BPA was only to the mother when she was pregnant. The offspring never were exposed to BPA,” Vandenbergh explained. “But when tested after they grew up, at 40 or 50 days old, there was a sharp difference between the ones exposed prenatally and those not exposed.
“The whole idea here — and it’s emerged from our work as well as other people’s — is that there’s a very sensitive period during fetal development and early infancy … and changes or exposure to chemicals during that time can induce changes that you may not see until the animal’s a full adult.”
Vandenbergh said recent research suggests that BPA exposure can actually alter an animal’s genome. If these changes, called epigenetic, occur early in an animal’s development, the impact may be more pronounced and long-lasting and – particularly disquieting where humans are concerned – the impact may not become apparent until adulthood.
“That’s the part that I find most compelling, and it’s also the part that makes it most difficult for the public to understand and for us to do human research,” Vandenbergh added. “It’s difficult to compare exposure and impact if the two are 20 years apart.”
It is not yet clear what, if any, action the federal government will take in regulating bisphenol A. The Canadian government has already moved to ban bisphenol A from products related to children, and some states are considering similar regulation.
And perhaps because children are involved, Vandenbergh said a good bit of self regulation appears to be occurring. He pointed out that shortly after the National Toxicology Expert Panel report was released, manufacturers of plastic water bottles began to replace BPA, while major retailers like Wal-Mart and Toys R Us have pulled children’s products containing BPA off the shelves.
— Dave Caldwell
Vandenbergh, professor emeritus in the Department of Zoology (now Biology) in the College of Agriculture and Life Sciences, served in 2007 and 2008 on a National Institutes of Health (NIH) National Toxicology Program Expert Panel charged with assessing the human health impact of bisphenol A, also known as BPA.
Bisphenol A is ubiquitous: Approximately 7 billion tons are produced around the world annually, Vandenbergh said. It is used to make polycarbonate plastic, which, in turn, is used in a wide range of consumer products, from CDs to eyeglass lenses to the liners of the cans in which food is packaged and other food containers.
That humans are exposed to BPA in their everyday lives is beyond dispute. In a recent study of approximately 2,500 Americans, 93 percent had BPA in their urine. The result of that exposure continues to be a matter for scientific inquiry and possible government regulation.
In August 2008, the federal Food and Drug Administration, which has the power to regulate BPA, released a report saying it is not necessary to regulate use of the chemical. Yet the next month, a study published in the Journal of the American Medical Association suggested a link between BPA and heart disease and diabetes in adults.
The National Toxicology Program committee on which Vandenbergh served reviewed much of the scientific literature on bisphenol A and came to the conclusion that for adults, there is a slight concern that the amounts of BPA to which we are typically exposed will have negative health impacts.
“If you’re an adult, you consume BPA; you metabolize it; it’s in your urine within 2 hours,” Vandenbergh explained.
But it’s a different story for fetuses, infants and children, and that’s where Vandenbergh’s expertise comes into play. The panel found reason for “some concern” that bisphenol A could negatively affect the health of people exposed to BPA either in the womb or as newborns. But negative health impacts – BPA can affect the brain and behavior – may not show up until adulthood.
“Your liver and mine are working pretty hard to break down these products, but if you are a newborn baby or a fetus, you don’t have the mechanism to break down this product; therefore, the dose you’re exposed to is higher,” Vandenbergh explained.
During his career, much of Vandenbergh’s work focused on better understanding the factors that influence the development of an animal while that animal is a fetus. For example, working with mice, Vandenbergh showed that the position of a mouse fetus in relation to other fetuses in the womb has an impact on how the adult animal develops.
“I was there (on the National Toxicology Program panel) because we had done quite a bit of work on the behavioral consequences of BPA exposure and have published two articles with graduate students on that topic, basically finding there was an increase in what’s called anxiety behavior in animals (exposed to BPA),” Vandenbergh said.
In experiments with mice, Vandenbergh found that a fetus need not be exposed directly to BPA to be affected by the chemical.
“The important thing is the exposure to BPA was only to the mother when she was pregnant. The offspring never were exposed to BPA,” Vandenbergh explained. “But when tested after they grew up, at 40 or 50 days old, there was a sharp difference between the ones exposed prenatally and those not exposed.
“The whole idea here — and it’s emerged from our work as well as other people’s — is that there’s a very sensitive period during fetal development and early infancy … and changes or exposure to chemicals during that time can induce changes that you may not see until the animal’s a full adult.”
Vandenbergh said recent research suggests that BPA exposure can actually alter an animal’s genome. If these changes, called epigenetic, occur early in an animal’s development, the impact may be more pronounced and long-lasting and – particularly disquieting where humans are concerned – the impact may not become apparent until adulthood.
“That’s the part that I find most compelling, and it’s also the part that makes it most difficult for the public to understand and for us to do human research,” Vandenbergh added. “It’s difficult to compare exposure and impact if the two are 20 years apart.”
It is not yet clear what, if any, action the federal government will take in regulating bisphenol A. The Canadian government has already moved to ban bisphenol A from products related to children, and some states are considering similar regulation.
And perhaps because children are involved, Vandenbergh said a good bit of self regulation appears to be occurring. He pointed out that shortly after the National Toxicology Expert Panel report was released, manufacturers of plastic water bottles began to replace BPA, while major retailers like Wal-Mart and Toys R Us have pulled children’s products containing BPA off the shelves.
— Dave Caldwell