The Trouble with Ingredients in Sunscreens

Sunscreen is a unique body care product: consumers are directed to apply a thick coat over large areas of the body and reapply frequently. Thus, ingredients in sunscreen should not be irritating or cause skin allergies, and should be able to withstand powerful UV radiation without losing their effectiveness or forming potentially harmful breakdown products. People can potentially inhale ingredients in sunscreen sprays and ingest some of the ingredients they apply to their lips, so ingredients must not be harmful to lungs or internal organs. Further, sunscreens commonly include ingredients that act as “penetration enhancers” and help the product adhere to skin. As a result, many sunscreen chemicals are absorbed into the body and can be measured in blood, breast milk and urine samples.

Active ingredients in sunscreens come in two forms, mineral and chemical filters. Each uses a different mechanism for protecting skin and maintain stability in sunlight. The most common sunscreens on the market contain chemical filters. These products typically include a combination of two to 6 of the following active ingredients: oxybenzone, avobenzone, octisalate, octocrylene, homosulfate and octinoxate. Mineral sunscreens use zinc oxide and/or titanium dioxide. A handful of products combine zinc oxide with chemical filters.

Laboratory studies indicate that some chemical UV filters may mimic hormones, and physicians report sunscreen-related skin allergies, which raises important questions about unintended human health consequences from frequent sunscreen application.

The Food and Drug Administration has not reviewed evidence of potential hazards of sunscreen filters – instead it grandfathered in ingredients used in the late 1970s when it began to consider sunscreen safety. The Danish EPA recently reviewed the safety of active ingredients in sunscreen and concluded that most ingredients lacked information to ensure their safety (Danish EPA 2015). Sixteen of the 19 ingredients studied had no information about their potential to cause cancer. And while the published studies suggest that several chemical filters interact with human sex or thyroid hormones, none of the ingredients had sufficient information to determine the potential risks to humans from hormone disruption.

EWG has reviewed the existing data about human exposure and toxicity for the nine most commonly used sunscreen chemicals. The most worrisome is oxybenzone, which was added to nearly 65 percent of the non-mineral sunscreens in EWG’s 2018 sunscreen database. The Centers for Disease Control and Prevention routinely detects oxybenzone in more than 96% of the American population. In a recent evaluation of CDC-collected exposure data for American children, researchers found that adolescent boys with higher oxybenzone measurements had significantly lower total testosterone levels. Three other studies reported statistically significant associations between oxybenzone exposure during pregnancy and birth outcomes.