Nalgene brand water bottles made with the controversial carbonate plastic… (David McNew/Getty Images )
The evidence for bisphenol A's negative health effects keeps piling up.
In a study released Monday in the Proceeding of the National Academy of Sciences, researchers at the Harvard Medical School reported that the chemical interferes with reproduction in the roundworm Caenorhabditis elegans.
Scientists had already shown that bisphenol A, which is used in many plastics and in the linings of food cans, is associated with reproductive troubles in humans and mice, the study reported. But examining the effects in C. elegans, which is often investigated to help understand human biology because it is easy to study, allowed the team to observe exactly why those reproductive problems arose.
The researchers exposed the worms to varying levels of bisphenol A. At the highest dose delivered -- which produced a level of BPA in the worms consistent with "high exposure" to the chemical in mice or humans -- the roundworms laid less than a quarter the number of eggs, on average, than worms that weren't exposed to the chemical. The few larvae that did hatch at that dose didn't live longer than three days. (The normal lifespan for C. elegans is around two to three weeks.)
According to the researchers, these results occurred because bisphenol A disrupted meiosis in the worms. Meiosis is the cell division process that produces eggs and sperm. Gene-bearing chromosomes in egg cell precursors in the worms exposed to high levels of bisphenol A were "frayed and fragmented," according to a news release.
Obviously, worms aren't people. But scientists have learned a lot about human biology from studing C. elegans in the past, and the Harvard team wrote that their research offered a "model of remarkable relevance to mammals with which to assess how our chemical landscape affects germ cells and meiosis," suggesting that bisphenol A might cause similar chromosomal damage in people.
Expect more investigations to follow.