April 28, 2009 -- With all of the bad press swirling around
certain types of plastic lately, regular old plastic water bottles have
maintained a reputation as safe, at least as far as human health is
concerned. New evidence, however, suggests that plastic water bottles may
not be so benign after all.
Scientists in Germany have found that PET plastics -- the kind used to
make water bottles, among many other common products -- may also harbor
hormone-disrupting
chemicals that leach into the water.
It's too soon to say whether drinking out of PET
plastic bottles is harmful to human health, said lead researcher Martin
Wagner, an ecotoxicologist at Goethe University in Frankfurt. But it now
appears possible that some as-yet unidentified chemicals in these plastics
have the potential to interfere with estrogen and other reproductive
hormones, just as the
infamous
plasticizers BPA and phthalates do. "What we found was really surprising to us," Wagner said. "If you drink
water from plastic bottles, you have a high probability of drinking
estrogenic compounds."
The study adds to growing concerns about products that span the plastic
spectrum, added Shanna Swan, an epidemiologist at the University of
Rochester School of Medicine and Dentistry in New York. "This is coming at a good time because the use of bottles for consuming
water is getting very bad press now because of its carbon footprint," she
said. "It's just another nail in the coffin of bottled water, the way I see
it."
Wagner and a colleague used genetically engineered yeast to analyze 20
samples of mineral water. Nine samples came our of glass bottles. Nine were
bottled in PET plastic. And two were in cardboard, juice-like boxes. The specialized yeast -- which change color in the presence of
estrogen-like compounds -- revealed estrogenic activity in seven of the
nine plastic bottles (and both cardboard samples), compared with just three
of the nine glass ones. Overall, Wagner said, levels of these compounds in
the water were surprisingly high.
German mineral water comes from natural springs. So, to see if the
estrogenic compounds were actually coming from the water itself, Wagner
emptied the bottles and replaced the water with a pure snail medium and a
tiny species of snail that is especially sensitive to estrogenic compounds.
Eight weeks later, female snails living in plastic bottles had more than
twice as many embryos inside their bodies compared to the glass-grown
snails. "Something from the plastic," Wagner said, "must have leached out
and changed the reproductive patterns of our snails."
Wagner cautions against jumping to conclusions. Water is still a healthy
beverage, he said. And until the compounds at work in the snail study have
been identified, it's just not possible to know if PET plastics pose a human
health risk. Still, tests in his lab have shown far less
estrogenic activity in tap water than in even the most "ultra-pure"
bottled waters.
"Having done all of these experiments, I started drinking tap water,"
Wagner told Discovery News. "It might have other stuff in it, but at least
it doesn't have estrogenic compounds." It may also be time, Swan said, to reconsider how safe the so-called
"safe" plastics really are. "I used to say: '4, 5, 1, and 2. All the rest are bad for you,'" she
said, referring to the recycling codes on plastic products. "Now, I'm not
saying that anymore. We don't know about 4, 5, 1, or 2. This raises
questions about all plastic bottles.
