May 8, 2019

The chemicals in your sunscreen are seeping into your blood. Is that unsafe?

Daily Briefing

    FDA in a study published Monday in JAMA found that a number of the active ingredients in popular sunscreens are absorbed into the bloodstream at levels higher than the agency recommends, prompting FDA to request further research on the safety of sunscreens.  

    Cheat sheets: Evidence-based medicine 101

    According to NBC News, the study is the first to identify the levels of systemic exposure to active ingredients in sunscreen.

    Study details

    For the study, FDA examined whether the active ingredients—avobenzone, ecamsule, octocrylene, and oxybenzone—found in four commercially available sunscreens are absorbed into the bloodstream at levels higher than 0.5 nanograms per milliliter (ng/mL). FDA guidelines currently recommend that manufacturers conduct further research on the safety of their products if absorption levels are above 0.5 ng/mL.

    The researchers enrolled 24 healthy participants in a clinical trial and randomly assigned each of the participants to apply one of the four sunscreens, which included:

    • One cream with 2% avobenzone, 10% octocrylene, 0% oxybenzone, and 2% ecamsule;
    • One lotion with 3% avobenzone, 6% octocrylene, 4% oxybenzone, and 0% ecamsule;
    • One spray with 3% avobenzone, 2.35% octocrylene, 6% oxybenzone, and 0% ecamsule; and
    • One spray with 3% avobenzone, 10% octocrylene, 5% oxybenzone, and 0% ecamsule.

    The researchers did not identify the sunscreen products used in the study.

    The participants applied the sunscreen products over 75% of their bodies four times per day for four days. The researchers collected 30 blood samples from each participant over seven days to determine the levels of the active ingredients that were absorbed into the participants' bodies.

    Findings

    The researchers found each of the four active ingredients were absorbed into participants' bloodstreams at levels higher than the 0.5 ng/mL level recommended by FDA. In particular, the researchers recorded mean maximum plasma concentrations of:

    • Avobenzone at 1.8 ng/mL for the cream, 4 ng/mL for spray one, 3.4 ng/mL for spray two, and 4.3 ng/mL for the lotion;
    • Ecamsule at 1.5 ng/mL for the cream, which was the only product containing that active ingredient;
    • Octocrylene at 5.7 ng/mL for the cream, 5.7 ng/mL for the lotion, 2.9 ng/mL for spray one, and 7.8 ng/mL for spray two; and
    • Oxybenzone at 169.3 ng/mL for the lotion, 209.6 ng/mL for spray one, and 194.9 ng/mL for spray two, which were the three products that contained that active ingredient.

    While each of the active ingredients were present at levels above FDA's recommendation, the researchers noted more research is needed to determine the potential effects.

    The researchers wrote that the findings do not mean individuals should discontinue using sunscreen.

    Discussion

    Robert Califf, a cardiologist and former FDA commissioner, and Kanade Shinkai, a dermatologist practicing at UCSF Medical Center, in an editorial accompanying the study wrote, "The demonstration of systemic absorption well above the FDA guideline does not mean these ingredients are unsafe." However, they wrote, "The study findings raise many important questions about sunscreen and the process by which the sunscreen industry, clinicians, specialty organizations, and regulatory agencies evaluate the benefits and risks of this topical [over-the-counter] medication."

    Theresa Michele, director of the division of nonprescription drug products at FDA and a co-author of the study, said, "It's very important from a public health perspective that people use them, especially as skin cancer rates are increasing. Right now, we know that there are benefits from these products and we don't know if there are any harms." She added, "That's why we are asking for additional data."

    Michele noted that individuals also can use other methods to protect themselves against ultraviolet rays. She said individuals "need to use sunscreen with other sun protecting measures, such as wearing protective clothing and sunglasses and staying out of the sun at peak hours."

    George Hruza, president of the American Academy of Dermatology (AAD), in statement said the active ingredients found in sunscreen "have been used for several decades without any reported internal side effects in humans." Hruza added, "Importantly, the study authors conclude that individuals should not refrain from the use of sunscreen, which the AAD encourages as one component of a comprehensive sun protection plan as sunscreen use has been shown to reduce the risk of skin cancer in a number of scientific studies."

    Elizabeth Platz, a professor at the Johns Hopkins Bloomberg School of Public Health, said consumers who feel concerned about using sunscreens with avobenzone, ecamsule, octocrylene, and oxybenzone can use products with other sun-blocking chemicals that FDA has deemed safe, such as zinc oxide and titanium dioxide. However, she that noted that products with those ingredients typically leave a white film on the skin.

    However, Alexandra Kowcz—chief scientist of the Personal Care Products Council, a trade association—noted that the study had some limitations. For example, Kowcz said participants applied sunscreen at levels "twice the amount that would be applied in what the scientific community considers real-world conditions." Kowcz expressed concern about the study possibly confusing consumers about the safety of sunscreen (Budryk, The Hill, 5/6; Carroll, NBC News, 5/6; Mishra, Reuters, 5/6; Matta et al., JAMA, 5/6).

    Cheat sheets: Evidence-based medicine 101

    Been awhile since your last statistics class? It can be difficult to judge the quality of studies, the significance of data, or the importance of new findings when you don't know the basics.

    Download our cheat sheets to get a quick, one-page refresher on some of the foundational components of evidence-based medicine.

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