In the largest to date, breast researcher Epidemiology University of Massachusetts Cancer Research phthalates and post-menopausal cancer in Amherst found no link between breast cancer risk and exposure to plasticizers and solvent chemicals used in such common products, such as shampoo, makeup, vinyl flooring , toys, medical devices and car showrooms.
Published in the Journal of the National Cancer Institute, the study "excludes any extreme increase in risk", but still leaves open the question of whether there is any connection between phthalate exposure and breast cancer, says Kathryn Reeves, Associate Professor at the School of Public Health and Science about health.
"Our research has caused almost as many questions as answers, and" - says Reeves. "I think this is an important contribution to the literature, but there is still a lot of work, including the search for young women."
Practically everyone in the United States are exposed to phthalates in varying degrees, mainly as a result of eating and drinking foods and liquids that come in contact with products containing chemicals. Once inside the body breaks down on phthalates metabolites are rapidly excreted in the urine and can be analyzed.
In a prospective study, which for the first time measured the effects of phthalate before staging a cancer diagnosis, Reeves and colleagues WM turned to Amherst Initiative for Women's Health (WHI), a long-term national study of health, which was attended by more than 160,000 postmenopausal women. Prospective cohort studies allow scientists to calculate the frequency of illness in a proper time sequence, setting exposure level before the result will be known, which provides a more convincing evidence than other types of studies.
UMass Amherst Researchers examined levels of 11 phthalate metabolites in urine samples from 419 women who had invasive breast cancer was diagnosed. They also examined samples from 838 healthy women who did not develop breast cancer.
According to Reeves, two or three urine samples were measured from each participant - the initial level, the 1st and 3rd year - to solve the two problems of studying the impact of phthalate. Previous studies have investigated urine samples after a diagnosis of breast cancer, when the impact could be caused by medical devices or medicines. In a study of Reeves' samples were collected when all are healthy, so we got the samples, which are not of concern that differences in exposure may be associated with the diagnosis and treatment. "
In addition, the analysis of several samples of urine will increase the probability of obtaining a more accurate picture of the impact. Reeves said half phthalate metabolites excreted in urine within 12-24 hours.
Despite the fact that the researchers analyzed several urine samples from each person, taken at intervals of several years, Reeves says that the study was not successful. "Phthalate exposure in humans varies with time, and it is difficult to describe the people who are most affected, and who the least - that's what we need to do in order to assess whether a higher exposure to phthalates breast cancer is associated with cancer risk "says Reeves. "The use of two or three specimens per person helped, but was not able to completely solve this problem."
as recommended in the study, so more attention in postmenopausal women not receiving hormone replacement therapy has been paid in future studies, because in this subgroup were marked "some potentially positive but not statistically significant" association between the level of phthalate metabolites and cancer risk of breast gland.
"We need to know the answer to that, cause if these chemicals breast cancer or other health effects", - says Reeves. "This is a critical issue, and we're trying to come up with creative ways to get not only the answer, but the right answer."