A new study from Harvard School of Public Health (HSPH)
researchers found that participants who drank for a week from
polycarbonate bottles, the popular, hard-plastic drinking
bottles and baby bottles, showed a two-thirds increase in
their urine of the chemical bisphenol A (BPA).
Exposure to BPA, used in the manufacture of polycarbonate
and other plastics, has been shown to interfere with reproductive
development in animals and has been linked with cardiovascular
disease and diabetes in humans. 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.
The study appears on the website of the journal Environmental
Health Perspectives and is freely available at https://www.ehponline.org/members/2009/0900604/0900604.pdf.
In addition to polycarbonate bottles, which are refillable
and a popular container among students, campers and others
and are also used as baby bottles, BPA is also found in dentistry
composites and sealants and in the lining of aluminum food
and beverage cans. (In bottles, polycarbonate can be identified
by the recycling number 7.) Numerous studies have shown that
it acts as an endocrine-disruptor in animals, including early
onset of sexual maturation, altered development and tissue
organization of the mammary gland and decreased sperm production
in offspring. It may be most harmful in the stages of early
"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,"
said Karin B. Michels, associate professor of epidemiology
at HSPH and Harvard Medical School and senior author of the
The researchers, led by first author Jenny Carwile, a doctoral
student in the department of epidemiology at HSPH, and Michels,
recruited Harvard College students for the study in April
2008. The 77 participants began the study with a seven-day
"washout" phase in which they drank all cold beverages
from stainless steel bottles in order to minimize BPA exposure.
Participants provided urine samples during the washout period.
They were then given two polycarbonate bottles and asked to
drink all cold beverages from the bottles during the next
week; urine samples were also provided during that time.
The results showed that the participants' urinary BPA concentrations
increased 69% after drinking from the polycarbonate bottles.
(The study authors noted that BPA concentrations in the college
population were similar to those reported for the U.S. general
population.) 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.
One of the study's strengths, the authors note, is that the
students drank from the bottles in a normal use setting. Additionally,
the students did not wash their bottles in dishwashers nor
put hot liquids in them; heating has been shown to increase
the leaching of BPA from polycarbonate, so BPA levels might
have been higher had students drunk hot liquids from the bottles.
Canada banned the use of BPA in polycarbonate baby bottles
in 2008 and some polycarbonate bottle manufacturers have voluntarily
eliminated BPA from their products. With increasing evidence
of the potential harmful effects of BPA in humans, the authors
believe further research is needed on the effect of BPA on
infants and on reproductive disorders and on breast cancer
"This study is coming at an important time because many
states are deciding whether to ban the use of BPA in baby
bottles and sippy cups. While previous studies have demonstrated
that BPA is linked to adverse health effects, this study fills
in a missing piece of the puzzlewhether or not polycarbonate
plastic bottles are an important contributor to the amount
of BPA in the body," said Carwile.