Page 378 - Environment: The Science Behind the Stories

CENTRAL CASE STUDYCENTRAL CASE STUDY

Poison in the Bottle:

Is Bisphenol A Safe?

Bisphenol A: Worldwide “Babies in the U.S. are born pre-polluted with BPA.

What more evidence do we need to act?”
— Dr. Janet Gray, Director of the Environmental Risks and
Breast Cancer Project, Vassar College
“There is no basis for human health concerns from
exposure to BPA.”

—The American Chemistry Council

How is it that a chemical found to alter reproductive devel- Americans carry detectable concentrations in their urine,
opment in animals gets used in baby bottles? How can it be according to the latest National Health and Nutrition Exami-
that a substance linked to breast cancer, prostate cancer, and nation Survey conducted by the Centers for Disease Control
heart disease is routinely used in food and drink containers? and Prevention (CDC). Because most BPA passes through the
The chemical bisphenol A (BPA for short) has been associated body within hours, these data suggest that we are receiving
with everything from neurological effects to miscarriages. Yet almost continuous exposure. Babies and children have higher
it’s in hundreds of products we use every day, and there’s a relative exposure to BPA because they eat more for their body
better than 9 in 10 chance that it is coursing through your body weight and metabolize the chemical less effectively.
right now. What, if anything, is BPA doing to us? To address such
To understand how chemicals that may pose health risks questions, scientists run experiments on laboratory animals,
come to be widespread in our society, we need to explore how administering known doses of the substance and measuring
scientists and policymakers study toxic substances and other the health impacts that result. Hundreds of studies with rats,
environmental health risks—and the vexing challenges these mice, and other animals have shown many apparent effects
pursuits entail. of BPA, including a wide range of reproductive abnormalities.
Chemists first synthesized bisphenol A, an organic com- Recent studies suggest humans suffer health impacts from
pound (p. 46) with the chemical formula C H O , in 1891. As BPA as well (see The Science behind The STory, pp. 380–381).
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they began producing plastics in the 1950s, chemists found Many of these effects occur at extremely low doses—
bisphenol A to be useful in creating epoxy resins used in lac- much lower than the exposure levels set so far by regulatory
quers and coatings. Epoxy resins containing BPA were soon agencies for human safety. Scientists say this is because BPA
being used to line the insides of metal food and drink cans and mimics the female sex hormone estrogen; that is, it is structur- CHAPTER 14 • Envi R onm E n TA l H EA lTH A nd T o xi C ology
the insides of pipes for our water supply, as well as in enamels, ally similar to estrogen and can induce some of its effects in
varnishes, adhesives, and even dental sealants for our teeth. animals (see Figure 14.9, pp. 388). Hormones such as estro-
Chemists also found that linking BPA molecules into gen function at minute concentrations, so when a synthetic
polymers (p. 47) helped create polycarbonate plastic, a hard, chemical similar to estrogen reaches the body in a similarly low
clear type of plastic that soon found use in water bottles, food concentration, it can fool the body into responding.
containers, eating utensils, eyeglass lenses, CDs and DVDs, In reaction to the burgeoning research, a growing number
laptops and other electronics, auto parts, refrigerator shelving, of researchers, doctors, and consumer advocates are calling
sports equipment, baby bottles, and children’s toys. With so on governments to regulate bisphenol A and for manufacturers
many uses, bisphenol A has become one of the world’s most- to stop using it. The chemical industry insists that BPA is safe,
produced chemicals; each year we make about 1 pound of pointing to industry-sponsored research that finds no health
BPA for each person on the planet, and 20 pounds per person impacts. To sort through the debate, several expert panels have
in the United States! convened to assess the fast-growing body of scientific studies.
Unfortunately, bisphenol A leaches out of its many prod- Some panels have found typical BPA exposure to be nothing to
ucts and into our food, water, air, and bodies. Fully 93% of worry about, others have expressed concern, and most have 377

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