Bad for Baby: New Risks Found for Plastic Constituent
Raloff, J., Science News
Two animal studies demonstrate that early exposure to a chemical known to leach from baby bottles, the linings of food cans, and other plastic items can trigger illness and even changes in genetic expression. A building block of polycarbonate plastics, bisphenol A (BPA) ends up in food, people, and the environment.
In one of the new studies, the pollutant permanently reprogrammed a gene in pups of mice fed BPA-laced chow.
The mice carried the Agouti gene, which is particularly vulnerable to what are called epigenetic changes. In such effects, hormones and other agents typically remove chemical units known as methyl groups from genes, or add them, interfering with the genes' function. Epigenetically affected Agouti mice, normally lean and brown-haired, become fat and blond (SN: 6/24/06, p. 392).
Randy L. Jirtle and his colleagues at Duke University in Durham, N.C., fed female mice chow that delivered 50 milligrams of BPA daily per kilogram of body weight throughout the animals' pregnancies and lactation periods. Blond fur and obesity in pups demonstrated Agouti reprogramming, say the researchers.
However, supplementing the mothers' diet with methyl-donating agents such as folate blocked BPA's epigenetic impacts, Jirtle's team reports in the Aug. 7 Proceedings of the National Academy of Sciences.
In a second study, Retha R. Newbold's team at the National Institute of Environmental Health Sciences (NIEHS) in Research Triangle Park, N.C., exposed new-born female mice to BPA for 5 days. Injected under the skin, doses ranged from 10 to 1,000 micrograms per kg of body weight.
Eighteen months later, the researchers examined the middle-aged animals' reproductive tracts and found more fertility-jeopardizing impairments than in a group of untreated mice. …