The Nuance
The Truth About Mineral vs. Chemical Sunscreens
Exploring the science — and lack thereof — behind sunscreen safety
For a 2019 study, researchers at the U.S. Food and Drug Administration had healthy people apply common, commercially available sunscreens.
For four days — and four times each day — the people in the study sprayed or rubbed sunscreen onto their bodies. Most sunscreen labels advise people to reapply “at least every two hours,” so the study was designed to assess what would happen inside the body if people followed this guidance. For example, if someone went on a beach vacation and slathered on sunscreen throughout the day, as directed, what, if anything, might show up in their blood?
To find out, the study team collected blood samples from each of the participants. They measured the samples for “systemic absorption,” or evidence that the active sunscreen chemicals had leached through the skin and into a person’s blood. Per FDA rules, systemic absorption above 0.5 ng/mL necessitates follow-up research to determine whether a chemical could be cancerous or associated with any developmental or reproductive harms.
The blood samples revealed that all three of the common sunscreen chemicals — avobenzone, oxybenzone, and octocrylene — exceeded…
