Sunscreen Protects the Skin, but Does It Harm the Body?

The FDA wants to know more about what happens when the lotions and sprays soak in.

Sunscreens protect against the harmful effects of ultraviolet radiation. But regulators don’t know the extent to which the over-the-counter drugs make it into the bloodstream or what happens to the body when they do.

The U.S. Food and Drug Administration wants to know—and if its proposed rule requesting manufacturers to provide the information is finalized in November, as planned, it may mean some ingredients now used to prevent sunburn will have to be removed from the market.

“The No. 1 thing we’re asking for is the absorption data,” said Theresa Michele, director of the FDA’s Division of Nonprescription Drug Products. “It stands to reason if you’re slathering yourself with a drug, one question you should ask is how much of that drug gets through the skin and into the body.”

In the past, the skin was believed to be largely impermeable, Dr. Michele said, but the medical community now knows that isn’t the case. Some products, such as nicotine and estrogen patches, even use skin as a delivery mechanism, counting on its ability to absorb the drugs.

In addition, sunscreens are now worn routinely by both children and adults, contributing to concerns about their safety, according to David Andrews, a senior scientist with the Environmental Working Group, a nonprofit research organization that rates sunscreens and other products.

In the U.S., at least 16 minerals and chemicals may be used as active ingredients in sunscreens. The FDA’s proposed rule rates the minerals zinc oxide and titanium oxide safe and effective. It doesn’t recognize PABA or trolamine salicylate as safe. And it concludes there is too little information to determine whether the 12 other chemicals are safe.

According to the FDA, if the active ingredients are absorbed into the bloodstream at a level of 0.5 nanograms per milliliter or higher, they should be tested to determine whether they increase the risk of cancer, birth defects or other adverse effects.

In a pilot study, four active ingredients in four commercially available sunscreens exceeded this threshold. The results were published in May in the peer-reviewed Journal of the American Medical Association.

The study, conducted by the FDA and Spaulding Clinical Research, a testing facility in West Bend, Wis., randomly assigned 24 healthy participants to use one of four sunscreens.

The tested products included two sprays, one lotion and one cream. Twelve men and 12 women ages 18 to 60 with no allergies or sensitivities to the products applied the sunscreens over 75% of their bodies four times a day for four days.

The researchers collected 30 blood samples from each participant over seven days and found that concentrations of each active ingredient exceeded the testing threshold after only one day.

The researchers didn’t conclude that people should avoid sunscreen—in fact, the FDA urges its continued use—but they did judge that further studies are needed.

“Just because something is absorbed doesn’t mean it’s unsafe,” Dr. Michele said. “What it means is you need to ask the next question. What does it do in the body?”

The FDA’s proposed rule was drafted in response to the 2014 Sunscreen Innovation Act and is expected to be finalized Nov. 26—although manufacturers may be granted additional time to test their ingredients.

So far, the industry has requested deferrals for eight chemicals, according to Linda Loretz, chief toxicologist of the Personal Care Products Council, a national trade association. Those eight are avobenzone, homosalate, octinoxate, octisalate, octocrylene, oxybenzone, ensulizole and meradimate.

Testing would cost $5 million to $6.34 million for each chemical, according to FDA estimates, or, altogether, as much as $50.7 million.

In comparison, Grand View Research, a San Francisco-based company that provides market information for various industries, estimated the U.S. sun-care market size at $1.95 billion in 2016, with sun-protection products accounting for 80% of total revenue.

It’s unclear how much time manufacturers might get to conduct testing, which they plan to do in cooperation with the FDA. But if their ingredients aren’t eventually recognized as safe and effective, they’ll have to be removed from sunscreens sold in the U.S.