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    Sunscreen Ingredient Linked to Endometriosis

    Study Ties a Common Ingredient in Sunscreens, Nail Polishes, and Lotions to Endometriosis

    Study Ties Benzophenones to Endometriosis

    Overall, the study found that only one kind of benzophenone, a chemical known as benzophenone-1, was significantly associated with the risk that a woman would have endometriosis.

    Women with the highest amounts of benzophenone-1 in their urine had a 65% greater chance of having endometriosis compared to women with the lowest levels.

    Benzophenone-1 is a chemical additive that's mostly used in nail polishes, according to the cosmetics industry web site, but it also forms when the body breaks down oxybenzone, the major ingredient in sunscreen.

    Differing Opinions

    "We find it to be a very weak study and quite unconvincing," says Linda Loretz, PhD, director of safety and regulatory toxicology for the Personal Care Products Council, a group that represents the interests of the cosmetics industry.

    Loretz points out that researchers had no information about whether the women used sunscreen or how much they used, which makes it impossible to know how they were exposed to the chemicals.

    "I don't think consumers should be concerned," she says. "I think safe sun practices are much more important."

    Women in the study who lived in California had higher benzophenone concentrations in their urine if they were tested during the summer months.

    That suggests that sunscreen is playing a role in exposure, says Sonya Lunder, MPH, a senior analyst with the Environmental Working Group (EWG) in Washington, D.C.

    A separate study by the CDC also found "higher concentrations in lighter-skinned people and also in the summertime, which points to the role of sunscreen in the measurement in our bodies," Lunder says.

    The Environmental Working Group publishes its own guide to sunscreen safety, and they have flagged oxybenzone, a chemical that's found in half of all sunscreens, as an ingredient that people should avoid.

    "We have raised concerns about it over the past couple of years as these kinds of studies come out -- our concern level matches up with it," Lunder tells WebMD.

    "The studies in people are still pretty small, pretty limited, but they are backed up by a series of laboratory studies finding that this chemical and this whole family of chemicals, really, has estrogenic effects," she says.

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