Dermatologists push back on sunscreen scare

Skin cancers

By David Rowley

10 May 2019

Dermatologists are trying to counter alarmist media stories about the safety of sunscreens after a small study showed active ingredients are absorbed into the systemic circulation.

Headlines like “Chemicals in sunscreen creep into our bloodstreams” and “Is sunscreen safe?” have appeared since a small US study of four commercially available sunscreens was published in JAMA.

Carried out by the US FDA’s Center for Drug Evaluation and Research (CDER), the study in 24 volunteers was based on maximal use: 75% skin coverage four times a day over a week.

It showed that after one day of use, the sunscreen ingredients avobenzone, oxybenzone, ecamsule, and octocrylene were absorbed into the circulation and plasma concentrations exceeded the threshold established by the FDA for waiving toxicology studies for sunscreens.

Under FDA regulations, topical agents do not require nonclinical toxicology tests for carcinogenicity or reproductive effects if the blood levels of ingredients are below 0.5 ng/mL.

Since all four of the sunscreen ingredients resulted in plasma levels in excess of this threshold, there was a need for further investigations to examine effects such as plasma levels after a single application and levels after long term application, the study authors said.

“The systemic absorption of sunscreen ingredients supports the need for further studies to determine the clinical significance of these findings,” they concluded.

But dermatologists have expressed concern that media coverage of the results may deter people from using sunscreens. The say most reports played down the study’s preliminary nature, small sample size and its concluding line; “These results do not indicate that individuals should refrain from the use of sunscreen”

Leading the pushback was Texas-based dermatologist Dr Ade Adamson who posted a “tweetorial” on social media to put the results in context.

Effect of Sunscreen Application on Plasma Concentration of Active Ingredients This provocative study in JAMA about sunscreen deserves a #tweetorial. Bear with me as I take you through the controversy and discuss sunscreen in general. ??????

He explained; “Whereas certain chemical sunscreens have been deemed as having insufficient data for safety of use….This does NOT mean that the chemical sunscreens are unsafe, it’s just that there is not enough data.”

“Importantly, the study says NOTHING about health effects of chemical sunscreen, but it does suggest that this needs to be studied. Also, this is maximum dosing, meaning in the real world because of poor application, sweating, swimming, sun exposure, levels in the blood are likely lower.”

He concluded: “Bottom line: this study shows that more work needs to be done to elucidate the potential health implications of chemical sunscreen absorption. However, there is little/weak evidence to suggest chemical sunscreen is harmful to health”.

His sentiments were echoed by Australian dermatologist Associate Professor Stephen Shumak who told SBS there was no evidence that sunscreen absorption had any adverse effects on the participants in the small  study that had used very large amounts of sunscreen, far more than would be normally used.

“The authors of the study themselves state that further studies are needed to determine what this preliminary finding means,” he said.

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