Do Microorganisms Make BPA in Plastics More Lethal?

Zebrafish embryos suffer more from BPA when it gets converted into new compounds by bacteria
Zebrafish embryos suffer more from BPA when it gets converted into new compounds by bacteria.

We worry a lot about bisphenol A (BPA) — a compound used to make plastics — and whether or not it harms us (and not just BPA, we worry about its substitutes as well). Now, to keep us more awake at night, scientist writer Erika Gebel reports in Chemical & Engineering News that a group of researchers have found that certain bacteria turn BPA into compounds more toxic to fish than BPA itself.

The pervasive BPA, which is produced by the millions of tons each year by industry, mimics the female sex hormone, estrogen. Scientists worry that BPA may disrupt normal hormonal levels in the body, especially in those of young children. The scientific jury is still out on whether or not BPA should be banned. To learn more, check out our previous post on BPA’s safety.

As Gebel reports:

Max Häggblom of Rutgers University knew that a significant amount of BPA ends up in the environment, where bacteria could transform it to compounds with unknown properties and health effects. So Häggblom and colleagues added BPA to four species of Mycobacterium, a common genus of microbe that the researchers knew could chemically transform related compounds. When they monitored the products with gas-chromatography/mass spectrometry, they discovered that all four species could add one or two methyl groups to BPA.

Häggblom’s team then added these methylated versions of BPA in varying concentrations, all of which were higher than BPA’s normal levels in nature, to tubes of water that contained zebrafish embryos. The researchers watched the fish as they developed and found that it took 10 times as much BPA as methylated BPA to kill half the zebrafish embryos over five days.

The specific chemistry that the microorganisms carry out is O-methylation on the BPA. The bacteria produce mono- and di-methyl ether derivatives of BPA. Both derivatives, according to Häggblom’s team, are more toxic than plain-old BPA.

Gebel notes that scientists have no data on whether these methylated BPA products exist in nature. But Häggblom told her that he hopes his team’s report in Environmental Science & Technology will prompt environmental chemists to start keeping an eye out for them.

Source: “A New Hazard From Bisphenol A?,” Chemical & Engineering News, 06/23/11
Image by asweeney100 (Adam Sweeney), used under its Creative Commons license.

Rajendrani "Raj" Mukhopadhyay is a science writer and editor who contributes news stories and feature articles on scientific advances to a variety of magazines. Raj holds Ph.D. in biophysics from Johns Hopkins University.