Are sunscreens dangerous?

A randomized clinical trial conducted by the U.S. Food and Drug Administration studied the effects of maximum sunscreen application on 24 healthy participants. In all cases, four chemicals were absorbed into the body at a level greater than FDA recommendations, but the long-term implications are unknown.

The study used four commercially available sunscreens to determine whether the active ingredients-avobenzone, oxybenzone, octocrylene, and ecamsule-are absorbed into systemic circulation. The sunscreens were tested in lotion, spray, and cream forms, with application to 75 percent of the body surface four times per day for four days, representing maximum use conditions. Blood samples were collected over seven days from each participant.

The results showed that all four products reached systemic concentrations greater than the FDA recommendation of 0.5 ng/mL after four applications on day one. The most common adverse event was rash, which developed in one participant with each sunscreen. The absorption rates were similar in all participants, regardless of age or skin type. The FDA stated that people should continue to use sunscreen, but says further studies are required, because the clinical relevance of systemic exposure is not well understood.

The American Academy of Dermatology issued a statement from George J. Hruza, MD, MBA, FAAD, president, regarding the study, saying “this is a small pilot study and more research is needed before it can be determined if the absorption of sunscreen ingredients has any effects on a person’s health.” Hruza’s statement notes that the ingredients have been used for several decades without any reported internal side effects. Skin cancer is the most common cancer in the United States, and unprotected exposure to the sun’s ultraviolet rays is a major risk factor for skin cancer.

The study authors say more research is needed to understand both short-term and long-term effects. While the current study was designed to represent maximum usage to areas of the body outside of normal swimwear over multiple days as might occur at the beach, absorption exceeding FDA guidelines occurred on day one, and for three of the four active ingredients, lasted until day seven.

A second phase of this study will use a different design to investigate how a single application is absorbed, skin concentration during washout phase, if chemicals are still in the body up to 17 days after the last dose, and systemic exposure to other common sunscreen ingredients including octinoxate, homosalate, and octisalate.

The Consumer Healthcare Products Association, an industry trade group, said in a statement that sunscreen manufacturers, the FDA, and dermatologists are aligned on the goal of protecting the public from the harmful effects of the sun, that previous FDA guidance has called for certain active ingredients to undergo further testing, and this study is consistent with those efforts.