Critics of the chemical bisphenol A or BPA have received powerful new ammunition in the form of a study from the Harvard School of Public Health (HSPH) which confirmed that the substance can leach from polycarbonate drinking bottles into humans.
The study revealed that participants who drank for a week from polycarbonate bottles and baby bottles showed a two-thirds increase of BPA in their urine.
According to HSPH: “The study is the first to show that drinking from polycarbonate bottles increased the level of urinary BPA, and thus suggests that drinking containers made with BPA release the chemical into the liquid that people drink in sufficient amounts to increase the level of BPA excreted in human urine.”
BPA, used in the manufacture of polycarbonate and other plastics, has been linked to cardiovascular disease and diabetes in humans and disrupted reproductive development in animals.
The chemical is commonly found in drinking bottles, baby bottles and sipper cups as well as dentistry composites and sealants and in the lining of aluminum food and beverage cans.
Karin B. Michels, associate professor of epidemiology at HSPH and Harvard Medical School and senior author of the study, commented: “We found that drinking cold liquids from polycarbonate bottles for just one week increased urinary BPA levels by more than two-thirds. If you heat those bottles, as is the case with baby bottles, we would expect the levels to be considerably higher. This would be of concern since infants may be particularly susceptible to BPA's endocrine-disrupting potential."
Harvard College students were recruited for the study which was conducted in April 2008. The 77 participants began the study with a week of drinking all cold beverages from stainless steel bottles in order to minimize BPA exposure. They were then given two polycarbonate bottles and asked to drink all cold beverages from the bottles during the next week. Urine samples were provided throughout the trial.
“The results showed that the participants' urinary BPA concentrations increased 69% after drinking from the polycarbonate bottles,” said HSPH. “Previous studies had found that BPA could leach from polycarbonate bottles into their contents; this study is the first to show a corresponding increase in urinary BPA concentrations in humans.”
BPA levels might have been higher had students drunk hot liquids from the bottles, the researchers note.
Canada banned the use of BPA in polycarbonate baby bottles last year and some polycarbonate bottle manufacturers have voluntarily eliminated BPA from their products.
Further research is needed to explore the effect of BPA on infants and on reproductive disorders and on breast cancer in adults, concluded the study.
The study appears on the website of the journal Environmental Health Perspectives and is available at http://www.ehponline.org/members/2009/0900604/0900604.pdf .