I have heard rumors lately that sunscreen can cause breast cancer. Sounds frightening doesn't it? Our tried and true enemy against skin cancer and wrinkling may be an enemy itself? Well, it doesn't seem to be true, but the answer is a little bit more complicated.
Here's the deal: some ultraviolet (UV) filters used in sunscreen may mimic estrogen according to animal and laboratory studies and thereby disrupt the endocrine system. Just to review a little human biology, the endocrine system uses hormones to regulate functions like metabolism, growth and development. However, there is no evidence that human exposure to these types of endocrine disruptors in the low levels used in sunscreen create health problems. In fact, a study using human volunteers found that even though UV filters were absorbed by the skin, they had no effect on the volunteers over all health or hormone levels, even estrogen.
Hopefully more research will be done on this matter. In the mean time, if you are concerned about messing with your endocrine system look for sunscreens containing zinc oxide or titanium dioxide (these block the UV rays rather than filter them), since these ingredients are not absorbed by your skin and they don't mimic estrogen.