Skin absorption of sunscreen ingredients into skin cause of concern: FDA Study
USA: Active ingredients present in the sunscreens can be systematically absorbed into the blood at levels that exceed the FDA threshold, raising safety concerns, finds an FDA study published in the journal JAMA. These findings, however, do not indicate that individuals should refrain from the use of sunscreen.
"In the absence of clear data demonstrating harm, the use of chemical sunscreen may still be considered appropriate; the use of mineral-based sunscreen is a well-established safe alternative," wrote the authors.
"UV radiation is the most important known modifiable risk factor for the development of skin cancer including melanoma. Behavioral measures to reduce this risk factor include seeking shade, wearing hats and protective clothing, avoiding outdoor activities during peak sunlight hours, and regularly using sunscreen.1 Sunscreen ingredients fall into 2 distinct categories: mineral or chemical. Mineral sunscreens contain physical UV filters, such as zinc oxide and titanium dioxide, that offer broad-spectrum UV coverage by reflecting or refracting UV radiation from skin. Chemical sunscreens contain UV filters that absorb UV radiation and when used in combination, can provide equal if not superior broad-spectrum UV filtration compared with mineral sunscreens," Adewole S. Adamson and Kanade Shinkai, from USA, explain in an accompanying editorial.
The study, by the U.S. Food and Drug Administration (FDA), is a follow-up to a 2019 investigation that had demonstrated the systemic absorption of 4 sunscreen active ingredients. However, there was a need to determine the systemic absorption of additional active ingredients and how quickly systemic exposure exceeds 0.5 ng/mL as recommended by the FDA.
Murali K. Matta, US Food and Drug Administration, Silver Spring, Maryland, and colleagues assessed the systemic absorption and pharmacokinetics of the 6 active ingredients (avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate) in 4 sunscreen products under single- and maximal-use conditions.
For the study, 48 healthy participants were randomized were randomized to 1 of 4 sunscreen products, formulated as lotion (n = 12), aerosol spray (n = 12), nonaerosol spray (n = 12), and pump spray (n = 12). Sunscreen was applied once on the first day and four times on days 2 through 4. Participants had 34 blood samples collected over 21 days.
The primary outcome was the maximum plasma concentration of avobenzone over days 1 through 21. Secondary outcomes were the maximum plasma concentrations of oxybenzone, octocrylene, homosalate, octisalate, and octinoxate over days 1 through 21.
Key findings of the study include:
- Among 48 randomized participants (mean [SD] age, 38.7 [13.2] years; 24 women [50%]; 23 white [48%], 23 African American [48%], 1 Asian [2%], and 1 of unknown race/ethnicity [2%]), 44 (92%) completed the trial.
- Geometric mean maximum plasma concentrations of all 6 active ingredients were greater than 0.5 ng/mL, and this threshold was surpassed on day 1 after a single application for all active ingredients.
- For avobenzone, the overall maximum plasma concentrations were 7.1 ng/mL for lotion, 3.5 ng/mL for aerosol spray, 3.5 ng/mL for nonaerosol spray, and 3.3 ng/mL for pump spray.
- For oxybenzone, the concentrations were 258.1 ng/mL for lotion and 180.1 ng/mL for aerosol spray.
- For octocrylene, the concentrations were 7.8 ng/mL for lotion, 6.6 ng/mL for aerosol spray, and 6.6 ng/mL for nonaerosol spray.
- For homosalate, concentrations were 23.1 ng/mL for aerosol spray, 17.9 ng/mL for nonaerosol spray, and 13.9 ng/mL for pump spray.
- For octisalate, concentrations were 5.1 ng/mL for aerosol spray, 5.8 ng/mL for nonaerosol spray, and 4.6 ng/mL for pump spray.
- For octinoxate, concentrations were 7.9 ng/mL for nonaerosol spray and 5.2 ng/mL for pump spray.
- The most common adverse event was rash, which developed in 14 participants.
"In this study, all 6 of the tested active ingredients administered in 4 different sunscreen formulations were systemically absorbed and had plasma concentrations that surpassed the FDA threshold for potentially waiving some of the additional safety studies for sunscreens," concluded the authors.
The study, "Effect of Sunscreen Application on Plasma Concentration of Sunscreen Active Ingredients: A Randomized Clinical Trial," is published in the journal JAMA.
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