The agency has been urging the companies that make sunscreens to do more safety studies of their products, but “for various reasons, it just never happened,” Shinkai says.
Finally, the FDA, which has a small research division, decided to take on the question of body absorption of sunscreen ingredients.
Last year, the agency dropped a bit of a bombshell after that testing revealed that four of the most common UV filters in chemical sunscreens — avobenzone, oxybenzone, octocrylene, and ecamsule — are absorbed by the body in substantial amounts, and can stay there for days, something that wasn’t well-known before.
As a result, the FDA says those four ingredients, along with another eight, need more safety testing before they can be considered GRASE. It has asked sunscreen makers to do that testing. So far, those studies — which are supposed to look at effects on cancer and reproduction — haven’t been done.
That’s despite the fact that the FDA gave sunscreen makers a November 2019 deadline to deliver more information.
Instead, some criticized the FDA’s initial testing methods, which had study volunteers reapply their sunscreens every 2 hours for 4 days, saying that most people don’t reapply that often and that the conditions tested in the study were unrealistic.
In response, the FDA redid the study, this time including six active ingredients in chemical sunscreens: avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate. Those ingredients are the UV filters that screen out the sun’s harmful rays.
They tested aerosol and pump lotions and sprays. They had 48 healthy adults — half were men and half were women — apply the sunscreens to 75% of their bodies, virtually anywhere a swimsuit wouldn’t cover.
On the first day, they applied the sunscreen just once. On days 2, 3, and 4, the men and women in the study took a shower in the morning, then applied the sunscreen every 2 hours for a total of four applications each day. Researchers took 34 blood samples from each study participant, for those first days of sunscreen use, and then later, after a week, 2 weeks, and 3 weeks, to see how long those chemicals might stay elevated in the body.