Another trial confirms active sunscreen ingredients are systematically absorbed into the body, as FDA calls for more data to establish the safety of 12 ingredients
A randomised clinical trial has found that all six tested active ingredients administered in four different sunscreen formulations were systematically absorbed into the body.
The study also found addition the plasma concentrations surpassed the FDA threshold for potentially waiving some safety studies for sunscreens, according to the results published in JAMA this week.
However the authors say this does not mean people should stop using sunscreen altogether.
Forty-eight participants were randomised to one of the four treatment groups that included four sunscreen product formulations: lotion (n = 12), aerosol spray (n = 12), non-aerosol spray (n = 12), and pump spray (n = 12).
Researchers assessed the systemic absorption and pharmacokinetics of six active sunscreen ingredients – avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate – over 21 days.
They found the systemic exposure of the tested active ingredients in all products exceeded the 0.5 ng/mL threshold on single application, and remained above the threshold until 23 hours after application.
A prior pilot study of 24 participants demonstrated systemic absorption of four sunscreen active ingredients.
This follow-up study expanded the sample size, tested additional active ingredients and formulations, and confirmed the initial finding of systemic absorption.
Studies in the literature have raised questions about the potential for oxybenzone and homosalate to affect endocrine activity.
In addition, multiple active ingredients lack non-clinical safety assessment data, including systemic carcinogenicity, developmental, and reproductive studies to determine the clinical significance of systemic exposure of sunscreen active ingredients.
The researchers emphasise that “these findings do not indicate that individuals should refrain from the use of sunscreens”.
However the FDA says it needs more data for 12 different active sunscreen ingredients to be able to make a positive determination that they can be “generally recognised as safe and effective”.
Of 16 currently marketed active ingredients, zinc oxide and titanium dioxide have been generally recognised as safe and effective.
Two ingredients – PABA and trolamine salicylate – are not considered safe and effective for use in sunscreens.
The FDA is asking industry and other interested parties for additional data on the remaining 12 ingredients.
“Broad spectrum sunscreens with SPF values of at least 15 are critical to the arsenal of tools for preventing skin cancer and protecting the skin from damage caused by the sun’s rays, yet some of the essential requirements for these preventive tools haven’t been updated in decades,” says the FDA.
“Since the initial evaluation of these products, we know much more about the effects of the sun and about sunscreen’s absorption through the skin.”
The FDA says it is making ongoing efforts “to ensure the safety and effectiveness of sunscreens”.
As this process proceeds, OTC sunscreen products will continue to be available on the market for consumer use.
Dr Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research, says it is important that as the FDA gather additional scientific information, “consumers continue to use sunscreen in conjunction with other sun-protection measures … given the recognised public health benefits of sunscreen use”.
“Sunscreens are only one element of a skin-cancer prevention strategy. Other sun protective behaviours include: wearing protective clothing that adequately covers the arms, torso and legs; wearing sunglasses and a hat that provides adequate shade to the whole head; and seeking shade whenever possible during periods of peak sunlight,” explains the FDA.