Two words: Bad plastic

Scientists now fear a chemical used in baby bottles and CDs, food cans and dental sealants, can disrupt fetal development and even lead to obesity.

By Elizabeth Grossman

Aug. 2, 2007 | You can't taste it or smell it, but if you ate canned soup for lunch or sipped from a shiny transparent water bottle at the gym, a chemical called bisphenol A probably entered your body. The American Chemistry Council tells us that bisphenol A makes our lives "healthier and safer, each and every day." But accumulating scientific research indicates the chemical may be adversely affecting women's ability to have children and children's reproductive health. Recent studies link bisphenol A to obesity, breast and prostate cancer, and neurological disorders.

Bisphenol A is a building block of the durable light plastics used in consumer products ranging from baby bottles to coffee makers to laptop computers, CDs to dental sealants to food can liners. It's a key ingredient of car parts, water filters, textiles, paper and a widely used flame retardant. "Everyone is exposed to it," says Dr. Hugh S. Taylor, reproductive endocrinologist at Yale University School of Medicine, who is studying the impact of the chemical on female reproductive health.

The official bisphenol A industry group Web site maintains its products "pose no known risks to human health." A growing number of scientists disagree, and bisphenol A, which appears to produce adverse impacts at low levels of exposure, is now at the center of a controversy challenging established methods of determining chemical safety.

In the past year, legislators in several states have introduced bills that would restrict local sale of infants' and children's products containing bisphenol A. In March, a class action lawsuit -- the first of its kind -- was filed in Los Angeles Superior Court against manufacturers and retailers of affected baby bottles and cups. In December 2006, San Francisco adopted a law that would ban the sale of baby products with bisphenol A. However, this May, in the wake of lawsuits by chemical and toy manufacturers, and a review by the city's health and environmental departments, the city repealed the ban, vowing to reconsider it in a year.

Americans have been increasingly using products made with bisphenol A since the 1940s. Between 1980 and 2000, U.S. production of bisphenol A grew nearly five times. Worldwide, over 6 billion pounds are now produced annually. This is big business. Sales of bisphenol A products, whose manufacturers include Bayer, Dow Chemical and General Electric, generate billions of dollars annually.

While bisphenol A has earned approval by the U.S. Food and Drug Administration for what are called "food contact" consumer products, the Centers for Disease Control has found bisphenol A in 95 percent of tested Americans at or above levels that have been found to cause abnormalities in animals. The FDA has responded that "impurities and processing aids" used in these plastics can migrate to food, but at much lower levels than those that have caused adverse effects in animal tests.

First recognized as a synthetic estrogen in the 1930s, bisphenol A belongs to a category of chemicals called endocrine disrupters because of their ability to interfere with hormone function. Endocrine disrupters interact in specific ways with the genetic receptors that determine a number of vital bodily mechanisms. In the case of bisphenol A, these apparently include egg cell, reproductive organ, and fat cell development. Its most profound effects appear to take place prenatally and in the early stages after birth.

Bisphenol A produces its adverse effects in "phenomenally small amounts," says Frederick vom Saal, professor of biology at the University of Missouri, Columbia, who has studied bisphenol A for over a decade. As vom Saal and other researchers point out, these levels are below those the FDA considers safe for daily human consumption.

Scientists have known that bisphenol A could leach from finished plastics since the early 1990s. That low levels of exposure could cause genetic abnormalities was discovered more recently.

In 1998, molecular biologist Patricia Hunt and colleagues at Case Western Reserve University were investigating chromosomal changes that occur in egg cells as animals age. The experiment compared mice with abnormalities to normal mice. "One day, the controls went bananas, showing a huge number of chromosomal abnormalities," recalls Hunt, now professor of molecular biosciences at Washington State University. The spike was so severe the researchers thought it must be caused by a chemical exposure. They discovered the contamination came from bisphenol A released by degrading plastic in the mouse cages.

Further upsetting traditional toxicology is that low doses of bisphenol A can produce adverse impacts while high doses may not. Hunt, Taylor and vom Saal explain that low levels of exposure during fetal development can cause lasting changes in reproductive and metabolic development. These changes to the fetus are permanent and irreversible, whereas impacts of adult exposure are reversible. "The fetus is exquisitely sensitive to bisphenol A," says Hunt. "One hit during a brief window of time can influence future development."

Next page: How bisphenol can cause animals to develop fat cells