Will Your Plastic Water Bottle Give You Breast Cancer?
Many myths surround breast cancer, as well as other claims that may have something to them. In the latter category is the claim that plastic water bottles cause breast cancer. We have some clues from experiments on animals in laboratory studies on rodents, and certain chemicals found in some plastics; but we do not know if these clues tell us anything about human beings. And keep in mind that we are talking about risk reduction; we know of no one thing that causes breast cancer, but there are several things that may increase your risk of getting it. In most instances we have to weigh those risks against perceived benefits.
There are different types of plastic bottles, containing different combinations of chemicals. Other plastics used for food packaging may also be of health concern. These are numbered according to the recycling number typically found on the bottom: #3 (polyvinyl chloride, a probable human carcinogen), #6 (polystyrene, a possible human carcinogen). More information can be found at the National Geographic's Green Guide website. Better choices, according to the Green Guide, are #1 (PET), #2 (high density polyethylene), #4 (low density polyethylene), and #5 (polypropylene). (I looked at the plastic bottles in my home and all of them are # 1.) Glass and metal bottles are options as well.
As you probably know, bisphenol A (BPA) is one chemical found in certain plastics. Every once in a while we hear that BPA might be connected to cancer. Just as quickly as this concern is raised, someone else says the cancer risk is unfounded. Which is it? We do not yet know. Again, these claims are based on studies in lab animals.
BPA can be found in many common household items: baby bottles, water bottles (labeled with the recycling symbol #7), food cans lined with polycarbonate resin, and plastic food containers to name a few. It is not surprising there has been so much coverage of BPA - it "hits close to home." No wonder it came up at the National Breast Cancer Coalition's recent Advocacy Training Conference, where science topics always generate vigorous debate.
On May 14, the U.S. Food and Drug Administration (FDA) testified before a Senate Subcommittee that, although the FDA's review of the chemical continues, "there is a large body of evidence that indicates that FDA-regulated products containing BPA currently on the market are safe and that exposure levels to BPA from food contact materials, including for infants and children, are below those that may cause health effects.
NBCCF does not completely share FDA's confidence in BPA's safety, given the growing body of evidence in animals that BPA is an endocrine disruptor. Endocrine disruptors are substances that either act like hormones or interfere with hormones in the body. We do not know if this interference increases breast cancer risk.
A large review that demonstrated the lack of consensus on BPA was released earlier this spring by the U.S. National Toxicology Program. This draft report on the safety of BPA stated that the chemical has been found in the urine of 93% of people aged six and older. The report did not identify any studies of health effects in humans, but it did express concern that BPA could "possibly" affect human development or reproduction.
In addition, this report presented some laboratory data from rodents showing reproductive effects and precancerous breast lesions as a result of exposure to BPA, at low levels of the chemical similar to what humans are exposed to. Another review, from 2005, analyzed many other studies in laboratory animals, wildlife, and cells and concluded that BPA is associated with a variety of hormone-like behaviors and health outcomes in animals, possibly at very low levels of exposure. We really do not know what this means for people at this point.
The National Cancer Institute and National Institute of Environmental Health Sciences are funding a multi-center study to measure BPA and other known and suspected endocrine-disrupting chemicals in 1200 nine-year-old girls. The studies will be following them for several years, to determine whether exposure to the chemicals is associated with changes in pubertal development, particularly aspects of development that are relevant to breast cancer.
I realize it can sometimes be hard to be a well-informed consumer. There is so much information, and not all of it is coming from sources you can trust. There is even more that we do not know. I can assure you that NBCC is following these issues carefully and will share with you new information as it comes to light.