A pilot study by the FDA's Center for Drug Evaluation and Research found that four common chemical sunscreen ingredients entered the bloodstream at significant levels after just one day of use, with some remaining in the body for at least 24 hours after application stopped. The findings, published in the medical journal JAMA, have raised questions about the long-term safety of these widely used sun-protection products, even as experts emphasize that sun protection remains essential.

The study tested 24 healthy volunteers who applied sunscreen containing avobenzone, oxybenzone, ecamsule, or octocrylene to 75% of their bodies four times daily for four days. Researchers collected 30 blood samples from each participant over seven days. By the end of day one, five of the six people using ecamsule cream showed statistically significant blood levels of the chemical. For the other three ingredients, all volunteers showed significant absorption after the first day.

One ingredient stood out dramatically: oxybenzone was absorbed into the body at 50 to 100 times higher concentrations than the other three chemicals tested. This finding is particularly concerning given oxybenzone's documented health effects and widespread use in American sunscreens.

Why Is Oxybenzone a Concern?

Oxybenzone has become the focus of intense scrutiny among environmental health researchers and regulators. The chemical has been linked to several health issues in scientific studies. A 2008 analysis by the Centers for Disease Control and Prevention (CDC) found oxybenzone in 97% of urine samples collected from study participants. Since then, research has suggested potential connections between oxybenzone exposure and lower testosterone levels in adolescent boys, hormone changes in men, and shorter pregnancies with disrupted birth weights in babies, though researchers caution that association does not prove causation.

Beyond human health, oxybenzone poses serious environmental risks. Hawaii, the Pacific nation of Palau, and Key West have all banned sunscreens containing oxybenzone and octinoxate because these chemicals cause coral bleaching and damage marine ecosystems. A Swiss study even detected oxybenzone in 85% of breast milk samples, raising concerns about newborn exposure.

Oxybenzone is also the most common cause of contact allergies among sunscreen ingredients. A 10-year study found that 70% of people had a positive patch test reaction when exposed to the chemical. Despite these concerns, oxybenzone remains in approximately two-thirds of all chemically based sunscreens sold in the United States, according to a 2018 report by the Environmental Working Group (EWG), a nonprofit research organization focused on environmental health.

What Do Experts Say About These Findings?

The FDA's discovery that sunscreen chemicals enter the bloodstream has sparked debate about whether absorption automatically means harm. Regulatory officials and dermatologists have emphasized that the presence of a substance in the blood does not necessarily indicate it is unsafe.

"Studies need to be performed to evaluate this finding and determine whether there are true medical implications to absorption of certain ingredients. In the meantime, people should continue to be aggressive about sun protection," said Dr. David Leffell, a dermatologist at Yale School of Medicine and spokesman for the American Academy of Dermatology.

Dr. David Leffell, Dermatologist at Yale School of Medicine

Scott Faber, senior vice president for government affairs at the Environmental Working Group, emphasized that the study serves an important regulatory purpose without necessarily indicating danger.

"The sun is the real enemy here. It's not news that things that you put on your skin are absorbed into the body. This study is the FDA's way of showing sunscreen manufacturers they need to do the studies to see if chemical absorption poses health risks," Faber explained.

Scott Faber, Senior Vice President for Government Affairs at the Environmental Working Group

David Andrews, senior scientist at the EWG, noted that the context of sunscreen use has changed dramatically since these chemicals were first approved. Originally, chemical sunscreens were used in small quantities to prevent sunburn during vacations. Today, dermatologists recommend daily application to large portions of the body, which prompted the FDA to begin requesting safety testing from manufacturers.

How to Choose Safer Sun Protection

• Consider Mineral Sunscreens: The Environmental Working Group recommends choosing mineral sunscreens containing titanium dioxide and zinc oxide when possible, as these ingredients sit on top of the skin rather than being absorbed into the bloodstream.
• Check for Banned Ingredients: Avoid sunscreens containing oxybenzone and octinoxate, which have been banned in Hawaii, Palau, and Key West due to environmental and health concerns.
• Consult a Dermatologist: The American Academy of Dermatology recommends talking to a board-certified dermatologist about which sunscreen formulation is best for your individual skin type and health profile.
• Apply Correctly: Use at least one ounce of sunscreen on all exposed skin, including your back, neck, face, ears, tops of your feet, and legs, reapplying every two hours or after swimming.

What Happens Next?

The FDA study has prompted calls for additional research to determine whether chemical absorption poses genuine health risks. Former FDA Chairman Dr. Robert Califf emphasized that the next steps should include appropriately designed clinical trials by manufacturers to test safety and determine optimal doses that prevent skin cancer while balancing potential risks.

Califf also highlighted an urgent research gap: the absorption rates and safety profile of sunscreen chemicals in infants and children, who have different body surface area to overall size ratios and may absorb substances at different rates than adults.

The Personal Care Products Council, the national trade association for sunscreen and cosmetic manufacturers, has offered alternative toxicological safety testing approaches to the FDA's current methodology. The council emphasized that the presence of sunscreen chemicals in the bloodstream does not necessarily lead to safety issues, particularly given that the FDA study used application rates twice higher than real-world conditions.

Despite ongoing research questions, health experts remain unanimous on one point: the risks of unprotected sun exposure far outweigh the current uncertainties about chemical sunscreen absorption. Skin cancer remains one of the most common cancers in the United States, with more Americans diagnosed with skin cancer each year than all other cancers combined. Melanoma ranks as the 19th most common cancer globally in both men and women, according to the World Cancer Research Fund.

The key takeaway from experts is clear: continue protecting your skin from the sun's dangerous ultraviolet rays while staying informed about emerging research on sunscreen safety. As the FDA and manufacturers conduct additional studies, consumers can make informed choices about which type of sun protection works best for their individual needs and values.