Sun Exposure

Active Ingredients in Sunscreen Exceed FDA Absorption Limits

Four active ingredients found in sunscreens exceed the maximal thresholds for systemic absorption established by the FDA, according to the findings of a recent study published in JAMA.

This preliminary study supports the need for nonclinical toxicology assessments, including systemic carcinogenicity and additional developmental and reproductive studies, the researchers said. However, consumers should not refrain from the use of sunscreen, they added.

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The trial included 24 healthy volunteers (58% were black) who were randomized to either spray 1, spray 2, a lotion, or a cream. Participants applied 2 milligrams of the sunscreen product per 1 cm2 to 75% of the body surface area 4 times per day for 4 days. A total of 30 blood samples were collected over 7 days from each participant. The researchers measured the maximum plasma concentration of avobenzone, oxybenzone, octocrylene, and ecamsule.

All products reached systemic concentrations greater than 0.5 ng/mL–the FDA threshold–after 4 applications on day 1, the researchers said.

The geometric mean maximum plasma concentrations of avobenzone were 4.0 ng/mL for spray 1, 3.4 ng/mL for spray 2, 4.3 ng/mL for the lotion, and 4.3 ng/mL for the cream, the researchers said. Corresponding values for oxybenzone were 209.6 ng/mL (66.8%) for spray 1, 194.9 ng/mL (52.4%) for spray 2, and 169.3 ng/mL (44.5%) for lotion. For octocrylene, corresponding values were 2.9 ng/mL (102%) for spray 1, 7.8 ng/mL (113.3%) for spray 2, 5.7 ng/mL (66.3%) for lotion, and 5.7 ng/mL (47.1%) for cream. In addition, the value for ecamsule was 1.5 ng/mL (166.1%) for cream.

Rash was the most common adverse event, which occurred in 1 participant with each sunscreen.

Limitations of this study included that it was conducted indoors without exposure to heat, sunlight, and humidity, which could affect the rate of absorption. In addition, the study was not designed to assess differences in absorption by formulation, age, or Fitzpatrick skin type.

“This randomized clinical trial demonstrated systemic exposure of 4 commonly used sunscreen active ingredients on application of sunscreen products under maximal use conditions consistent with current sunscreen labeling (ie, apply at least every 2 hours),” the researchers concluded. “The clinical effect of plasma concentrations exceeding 0.5 ng/mL is unknown, necessitating further research.”

—Melissa Weiss


Matta MK, Zusterzeel R, Pilli NR, et al. Effect of sunscreen application under maximal use conditions on plasma concentration of sunscreen active ingredients: A randomized clinical trial [published online May 06, 2019]. JAMA. doi:10.1001/jama.2019.5586.