For decades, dermatologists have instructed people enjoying the bright summer sun to use sunscreen. They also advise reapplying sunscreen, wearing sunscreen on cloudy days, and even using sunscreen daily year-round. It's true - and important to reiterate - that protection from the sun’s damaging UV rays can prevent sunburns, skin cancers, and signs of aging. However, according to a recent article in the Journal of the American Medical Association (JAMA), sunscreens may also have some unwanted effects. 

Upturning long held beliefs, the preliminary study found the active ingredients in common sunscreens are absorbed into the blood. Since sunscreens are intended for external use, researchers haven’t yet evaluated the safety  of many components after internalization. This is alarming because scientists have already raised concerns about the toxicity of common sunscreen ingredients, like oxybenzone and octinoxate. Importantly, the JAMA paper only stated the need for more study and did not make conclusions about the safety of sunscreen.

Oxybenzone and octinoxate mimic the hormone estrogen. In the body, these look-alike molecules disrupt normal hormone function which affects the reproductive system and can be carcinogenic. Furthermore, these chemicals are linked to declining coral reefs and other marine life.  Evidence that sunscreens are harmful to marine ecosystems was strong enough that Hawaii banned sunscreens containing these ingredients last year. Since the FDA still approves them, it might be worth looking more closely at the ingredients of your sunscreen and how you use it. The benefits of using sunscreen may still outweigh the risks, but it is good to be an informed consumer.