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22 September 2011

BPA, methylparaben block breast cancer drugs


San Francisco researchers have discovered that two chemicals commonly used in consumer products - bisphenol A and methylparaben - can interfere with the effectiveness of drugs used to fight breast cancer.The research by doctors from California Pacific Medical Center in San Francisco is part of a growing body of evidence looking at the negative health effects of BPA, a plastic hardening chemical found in food containers, cans and even sales receipts, as well as methylparaben, a lesser-known preservative found in cosmetics and personal care products.


Scientific studies have linked the chemicals to hormonal problems and reproductive health issues, among other problems.In the latest study, researchers took noncancerous breast cells from high-risk patients, grew them in a laboratory and found that once the cells were exposed to bisphenol A and methylparaben, they started behaving like cancer cells.


Tamoxifen, a drug designed to prevent or treat cancer, slows down the growth of both healthy and cancerous breast cells and ultimately leads to their death. But when tamoxifen was introduced in the lab, the cells exposed to the two chemicals kept growing and didn't die, said Dr. William Goodson, senior clinical research scientist at California Pacific Medical Center Research Institute and lead author of the study.The results are being published online this week in the medical journal Carcinogenesis.


The study looks at the fundamental mechanisms of how normal breast cells behave when exposed to BPA or methylparaben, said Dr. Mhel Kavanaugh-Lynch, director of the California Breast Cancer Research Program.Chemicals such as BPA and methylparaben mimic or interfere with the body's endocrine or hormonal systems.


"We have a lot of information that makes these endocrine disruptors appear to be bad things to be exposed to, but there are very few, if any, studies that show a direct causal link," Kavanaugh-Lynch said.


Breast cancer rates have been growing over the past 30 years. While some of the reason can be attributed to hormone-replacement therapies or other issues specific to women, researchers have noticed that breast cancer rates are going up by about the same amount in men as in women.


"It's mostly a women's disease, but when more men are getting more breast cancer, you have to wonder where the hormones are coming from," Goodson said.Goodson said BPA and methylparaben are hard to avoid because they are used so widely and are even found in household dust. He said he does not know whether the effects of exposure to the chemicals are reversible.

Source: San Francisco Chronicle
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