Q. I am a breast cancer survivor. I play tennis and golf five days a week and smear a high SPF sunscreen all over my body. I also wear protective clothing to block the sun.
I have heard that some sunscreens may have estrogenic activity. I’m supposed to avoid estrogen, so I wonder if you can tell me more about sunscreens and estrogen.
A. Several common ingredients in sunscreens have been shown to act like estrogen. One test-tube study showed that breast cancer cells grew faster in the presence of such compounds.
Another study showed that sunscreen ingredients are absorbed through the skin and can be measured in the urine (Journal of Investigative Dermatology, July 2004). The significance of this finding for adults remains controversial, but the authors warn that young children may be vulnerable to hormonal disruption from such sunscreens.
Until this issue has been resolved it might be prudent to stick with protective clothing. (Check www.sundayafternoons.com or www.coolibar.com.) Sunscreens that contain physical blockers such as zinc oxide or titanium dioxide don’t have hormonal effects and are safe for young children and people with sensitive skin (The Lancet online, May 3, 2007).