Chemical used in cleaning materials may induce breast cancer
us scientists have found that 4-nonylphenol (4- np), a chemical released into the environment from cleaning materials, textiles and plastics, mimics the female sex hormone oestrogen and hence it may act as a trigger for breast cancer.
Once 4- np enters the body, it stimulates an enzyme system in the liver, which boosts the production of estriol, a hormone similar to oestrogen. Also, 4- np binds itself to the oestrogen-receptors in the breast, which can result in a more rapid cancer growth than caused by oestrogen itself. The study by researchers at the University of Texas and the Clemson University in Southern Carolina appeared in July in the online version of the Journal of Applied Toxicology .
To assess its ability to cause breast cancer, the researchers compared the effect of giving various doses of 4- np and oestrogen to mice.
In one set of experiments, they discovered that while 4- np indeed stimulates estriol metabolism in the liver, it doesn't lead to increased levels of estriol in the bloodstream. The researchers conclude that as well as stimulating enzymes that in turn produce estriol, it must also have a direct inhibiting affect on estriol production.
In a second set of experiments, they gave a variety of doses of 4- np or oestrogen to mice that are genetically engineered to readily develop breast cancer. Monitoring them over 32 weeks, the researchers found many of the mice given 4- np developed breast cancer. Those given equivalent doses of oestrogen based on the relative binding affinities of nonylphenol and estradiol for their receptor, did not develop cancer.
William Baldwin from the University of Texas, who worked on the study, said a long-term contact with 4- np significantly increases the risk for breast cancer in humans. Breast cancer is the most commonly diagnosed cancer in women and environmental factors appear to cause about three-quarters of the cases. Many of the environmental factors increase a woman's levels of the hormone oestrogen, which is thought to be a major contributing factor in the disease.
Meanwhile, another study showed that several soy and herbal supplements have oestrogen-like actions and hence potentially heighten breast cancer risk, says co-author Barbour Warren of Cornell University.
He points to not only a lack of well-designed clinical trials but also to a lack of any regulations regarding effectiveness or quality control in formulating these supplements and says that women with a high risk of breast cancer should be particularly cautious.
"Just because herbal medicines are 'natural' products does not mean that they are safer than conventional medicines," he said. The ingredients used in herbal medicines can also have adverse effects and lead to several health problems, he warned.
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