Scientists are reporting a possible link between an ingredient in some sunscreen products that mimics estrogen and an increased risk of endometriosis.

The study, published in the American Chemical Society journal Environmental Science & Technology, is the first to suggest a potential connection between benzophenone (BP)-type ingredients and the painful uterine condition.
Lead researcher Kurunthachalam Kannan noted some sunscreens and other personal care products contain BPs, which block ultraviolet rays from the sun. BPs can be absorbed into the blood, where they mimic the effects of the female hormone estrogen.
For the study, the scientists analyzed BP levels in 625 women with endometriosis. They found that high levels of one BP -- called 2,4OH-BP -- were associated with an increased risk of the uterine condition.
Women tended to have higher levels of BPs in the summer months and if they lived in sunny climates.
"Our results invite the speculation that exposure to elevated 2,4OH-BP levels may be associated with endometriosis," said the researchers.
Endometriosis affects up to 1 in 10 women.
The study was funded, in part, by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the National Institutes of Health.