Although Bisphenol A (BPA) has generated considerable consumer, regulatory, and media attention recently, it was isolated as a possible risk in findings published in 1993 by a team of researchers at Stanford University’s School of Medicine. David Feldman, emeritus professor of endocrinology, said his team happened upon the chemical, which is believed to mimic the hormone estrogen, by accident. As part of their studies, the researchers looked for receptors and hormones in a yeast tissue culture medium, which it autoclaved, or sterilized, in a polycarbonate (PC) flask. The scientists used mass spectrometry to determine the source of an estrogen imitator they were increasingly encountering, with Feldman and his team discovering that the estrogenic molecule they were finding was BPA. Subsequent experiments revealed that the BPA was present even in small samples of pure water microwaved in the PC flasks.

“At that point,” Feldman said in a press release from the university, “[the research team] realized that we had identified a molecule that was leaching out of the plastic that, because of its estrogenic hormone-like properties, had the potential to be important and perhaps even dangerous to people who were eating or drinking out of containers made of this type of plastic, polycarbonate.” The researchers sent results to the company that made the flasks, but it was unable to find any BPA. Feldman determined it was the sensitivity of the university’s biological tests—5 to 10 parts per billion—that led to the discrepancy, with the manufacturer only identifying levels of more than 25 to 50 parts per billion.

BPA’s presence does not conclusively equate to deleterious effects, according to Feldman, with more studies needed. “In fact, to date there have been no studies showing that bisphenol A exposure affects human health,” Feldman explained. Feldman supports a “better safe than sorry approach” to BPA exposures, adding that the effects of “environmental estrogens” or “endocrine disrupters” are additive, making caution prudent. “There are many different ways we can be exposed to these various compounds and they are cumulative,” he stated.—[email protected]