Scientists have demonstrated for the first time that polycarbonate
containers release the chemical bisphenol A (BPA) into liquid stored in
BPA has been shown to interfere with reproductive
development in animals and has been linked with cardiovascular disease
and diabetes in humans.
Experts warned that
babies are at greater risk, because heating baby bottles increases the
amount of BPA released, and the chemical is potentially more harmful to
Study author Karin B. Michels, associate professor of
epidemiology at HSPH and Harvard Medical School, said: "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."
77 students took part in the study after a seven-day "washout" phase in
which they drank all cold beverages from stainless steel bottles in
order to minimise BPA exposure.
They were then given two polycarbonate bottles and asked to drink all cold beverages from the bottles during the next week.
results showed the volunteers' urinary BPA concentrations increased 69
per cent after drinking from the polycarbonate bottles.
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studies had found that BPA can be transferred from polycarbonate
bottles into their contents, but this study is the first to show a
corresponding increase in urinary BPA concentrations in humans.
of the study's strengths, said the research published in Environmental
Health Perspectives, is that the students drank from the bottles in a
Additionally, the students did not wash their
bottles in dishwashers or put hot liquids in them, as heating has
already been shown to increase the leaching of BPA from polycarbonate.
banned the use of BPA in polycarbonate baby bottles in 2008 and some
manufacturers have voluntarily eliminated BPA from their products.
increasing evidence of the potential harmful effects of BPA in humans,
the study's authors believe further research is needed into BPA's
impact on babies, and on reproductive disorders and breast cancer in
Most adults carry BPA in their bodies, but expert opinion on the risks is divided.
European Food Safety Authority believes that people naturally convert
the chemical into less harmful substances into the body.
researcher Jenny Carwile said: "While previous studies have
demonstrated that BPA is linked to adverse health effects, this study
fills in a missing piece of the puzzle – whether or not polycarbonate
plastic bottles are an important contributor to the amount of BPA in
BPA is also found in dentistry composites and sealants and in the lining of aluminium food and beverage cans.