Testimony on BPA
By Ted Schettler MD, MPH Testimony in support of House Bill 33; General Assembly of Maryland
An Act concerning child care articles and toys containing bisphenol A
(Note this legislative testimony provides a brief history of the science on the chemical bisphenol A.)
Thank you for the opportunity to testify today in support of House Bill 33. My name is Ted Schettler. I am a physician and I also have a masters degree in public health. In addition to traditional medical sciences, I have training in epidemiology and toxicology.
This bill addresses an issue of significant public health concern. Exposures to BPA are nearly ubiquitous. More than 90% of people in the US have measureable levels of BPA in their urine. On average, children have levels about 50% higher than adults. Workers making BPA-containing products are exposed to higher levels.
Bisphenol A is a building block of polycarbonate plastic and an ingredient in the resin lining of many food and beverage containers. BPA can leach out, contaminating their contents. BPA from various consumer products also contaminates the general environment, including house dust. This can be a significant pathway of exposure, particularly for children.
By the time it is excreted in the urine, BPA has largely been transformed into an inactive form. But the blood concentration of the active form of the chemical varies with age as well as exposure level. It is higher in developing children. This is because fetuses and infants have not yet fully developed pathways to metabolize BPA as rapidly as adults. As a result, they are exposed to the active form of the chemical for a longer time. The active form of BPA is also present in human amniotic fluid, showing that the developing human fetus is exposed as well.
BPA is weakly estrogenic…that is, it mimics naturally occurring estrogen, though it is less potent. It has other mechanisms of action as well. It interferes with insulin, testosterone, and thyroid hormone signaling, as well as other biochemical pathways.
Extensive laboratory studies show that BPA interferes with normal development after fetal or infant exposures. Among the outcomes, early life exposures in animal studies increase the susceptibility to breast and prostate cancer later in life, accelerate the onset of puberty in females, alter male reproductive tract development and fertility, and change gender-dependent behavior patterns.
Two years ago, after an extensive literature review, a committee of the National Toxicology Program of the NIH concluded that they had concern about the effects of BPA on the developing brain, behavior, and prostate gland in humans at current exposure levels.
At that time, there were no published human studies assessing health effects in people. Since then, a 2008 study published in the Journal of the American Medical Association, based on the Center for Disease Control’s biomonitoring data, reported a correlation between BPA levels and the likelihood of an individual having diabetes or cardiovascular disease. A more recent analysis with a larger sample size over additional years found the same correlation. Although this kind of correlational study cannot prove that BPA is responsible for the increased likelihood of these common diseases, the findings are consistent with laboratory studies showing effects of BPA on various metabolic functions, including the onset of insulin resistance….the hallmark finding in type 2 diabetes, which is so prevalent in our communities.
A December 2009 study of 229 pregnant women reported a correlation between higher maternal BPA levels during pregnancy and increases in aggressive and hyperactive behavior in their daughters at 2 yrs. of age. As with most epidemiologic studies, this one has its limits and is not conclusive. It needs to be expanded and repeated. But it is consistent with the laboratory animal data showing changes in behavior that caused the NTP committee concern.
In June, 2009 the Endocrine Society, a professional organization of endocrinologists, issued a consensus statement on hormone disruptors including BPA. The statement calls for “regulation seeking to decrease human exposure to the many endocrine-disrupting agents” and specifically cited BPA as a chemical of concern.
Just two weeks ago, the US FDA revised their previous position with respect to BPA and said that the agency now “shares the perspective of the National Toxicology Program that recent studies provide reason for some concern about the potential effects of BPA on the brain, behavior, and prostate gland of fetuses, infants and children.”
In 2008 the National Academy of Sciences published a report titled “Science and Decisions: Advancing Risk Assessment”. They proposed changes to the traditional risk assessment model, using a framework that begins with a “signal” of potential harm….for example, a suspicious disease cluster….or the presence of a hazard. Under the traditional paradigm, the question has been, “What is the probability and consequence of an adverse health effect posed by that signal?” In contrast, the newly recommended framework asks from the outset, “What options are there to reduce the hazards or exposures?”
That is what this bill would do. It would reduce this hazard in consumer products intended for children. And it will likely also reduce exposures in workers who manufacture those products.
Adopting this bill will show that you choose to avoid a problem, rather than attempting to manage it or accept the consequences. Human studies of BPA impacts are only beginning to emerge. Yet, it’s unlikely we will ever really know if early life exposures to BPA increase the risk of prostate or breast cancer decades later. This would be extraordinarily difficult if not impossible to study. With over 90% of the population exposed to this chemical, you do not want to be wrong. Even small increases in risks of diseases spread over a large population have large public health consequences….for which we all pay. I urge your support for this bill.