May 14, 2019
2 min read

More data needed on plasma concentrations of sunscreen ingredients

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When sunscreens were used under maximal use conditions, plasma concentrations exceeded the threshold established by the FDA for waiving some nonclinical toxicology studies for sunscreens, according to data published in JAMA.

A randomized clinical phase 1 trial enrolled 24 healthy volunteers aged 18 to 60 years who were randomly assigned to use one of four commercially available sunscreen products.

Spray 1 contained 3% avobenzone, 6% oxybenzone, 2.35% octocrylene and 0% ecamsule; spray 2 3% avobenzone, 5% oxybenzone, 10% octocrylene and 0% ecamsule; a lotion 3% avobenzone, 4% oxybenzone, 6% octocrylene and 0% ecamsule; and a cream 2% avobenzone, 0% oxybenzone, 10% octocrylene and 2% ecamsule.

Sunscreen was applied outside the normal swimwear area four times a day for 4 days. Over 7 days, 30 blood samples were taken from each participant.

One participant using the cream discontinued on day 2 because of milia. Rash was the most common adverse event, reported in 17% of participants.

All four products resulted in avobenzone exposures. Plasma concentration exceeded 0.5 ng/mL on day 1 for all products, continuing through day 7 for all except the cream, according to the researchers. For all products, area under the curve and maximum plasma concentration increased from day 1 to day 4.

Geometric mean maximum plasma concentrations were 4.0 ng/mL (coefficient of variation, 60.9%) for spray 1, 3.4 ng/mL (77.3%) for spray 2, 4.3 ng/mL (46.1%) for lotion and 1.8 ng/mL (32.1%) for cream.

Woman applying sunscreen 
Woman applying sunscreen.

The three products with oxybenzone resulted in oxybenzone exposure and plasma concentrations exceeding 20 ng/mL on day 7. Geometric mean maximum plasma concentrations were 209.6 ng/mL (coefficient of variation, 66.8%) for spray 1, 194.9 ng/mL (52.4%) for spray 2 and 169.3 ng/mL (44.5%) for lotion.

Participants who received oxybenzone formulations had plasma concentrations exceeding 0.5 ng/mL within 2 hours after the first application on day 1.

All four products contained octocrylene. Geometric mean maximum plasms concentrations were 2.9 ng/mL (coefficient of variation, 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 those who received products with the three highest concentrations of octocrylene, plasma concentrations exceeded 0.5 ng/mL within 6 hours of the first use. In addition, terminal half-life was long at a mean of 42 to 84 hours.

Only the cream contained ecamsule, and five of the six participants had plasma concentration exceeding 0.5 ng/mL on day 1. The geometric mean maximum plasma concentration was 1.5 ng/mL (coefficient of variation, 166.1%).


Another phase of the study will investigate additional questions raised by this study, such as maximum plasma concentration after a single application.

The current study had several limitations. It was conducted without exposure to heat, sunlight and humidity, and these environmental factors may alter the absorption of the active ingredients.

“The systemic absorption of sunscreen ingredients supports the need for further studies to determine the clinical significance of these findings. These results do not indicate that individuals should refrain from the use of sunscreen,” the study authors wrote. – by Abigail Sutton


Disclosures: The authors report no relevant financial disclosures.