Parabens are preservatives used in some sunscreens and also in a variety of cosmetic products. Preservatives are used in products to prevent growth of microorganisms that can cause infection, much like preservatives used in food.
Questions have been raised about whether parabens have the ability to promote tumor growth, specifically breast tumors, because of their potential estrogen-like effects.
However, studies so far have not shown this to be a legitimate concern. According to an FDA statement on the topic, last updated in June 2011:
"… FDA is aware that estrogenic activity in the body is associated with certain forms of breast cancer. Although parabens can act similarly to estrogen, they have been shown to have much less estrogenic activity than the body's naturally occurring estrogen. For example, a 1998 study (Routledge et al., in Toxicology and Applied Pharmacology) found that the most potent paraben tested in the study, butylparaben, showed from 10,000- to 100,000-fold less activity than naturally occurring estradiol (a form of estrogen). Further, parabens are used at very low levels in cosmetics. In a review of the estrogenic activity of parabens, (Golden et al., in Critical Reviews in Toxicology, 2005) the author concluded that based on maximum daily exposure estimates, it was implausible that parabens could increase the risk associated with exposure to estrogenic chemicals.
FDA believes that at the present time there is no reason for consumers to be concerned about the use of cosmetics containing parabens. …"
So, even if sunscreen can pass through the skin in minute quantities, there are no studies in humans that link parabens to any form of cancer. We do know, however, that ultraviolet radiation from the sun does lead to DNA damage and increased risk of skin cancer, especially melanoma, a potentially fatal skin cancer.
Bottom line? Use Sunscreen!
Anyone still concerned about parabens, can always choose sunscreens and cosmetics without them by reading product labels. According to the FDA:
"Cosmetics sold on a retail basis to consumers are required by law to declare ingredients on the label. This is important information for consumers who want to determine whether a product contains an ingredient they wish to avoid. Parabens are usually easy to identify by name, such as methylparaben, propylparaben, butylparaben, or benzylparaben."
More skin cancer prevention tips from Roswell Park Cancer Talk: Have Fun in the Sun Safely