Jan. 21 (UPI) -- Sunscreen protects skin from the sun's harmful rays, reducing risk for certain types of cancer.
However, could it's use introduce other problems?
That's the key question raised by findings published Tuesday in the Journal of the American Medical Association by researchers from the U.S. Food and Drug Administration, which suggest that the bodies of users of these suntan lotions and oils likely absorb several of their active chemical ingredients.
In fact, the analysis revealed that the levels of these chemicals found in users' blood in some cases surpassed the agency's threshold "for potentially waiving some of the additional safety studies" for these products.
"There is evidence that some sunscreen active ingredients may be absorbed," Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, said in a statement issued by the agency. "However, the fact that an ingredient is absorbed through the skin and into the body does not mean the ingredient is unsafe. Rather, this finding calls for further industry testing to determine the safety and effect of systemic exposure of sunscreen ingredients, especially with chronic use."
Indeed, the FDA analysis focused on six active ingredients in several sunscreen products -- the chemicals avobenzone, oxybenzone, octocrylene, homosalate, octisalate and octinoxate -- and was designed to assess their absorption through the skin and into the body "under single dose and maximal use conditions." A similar study published earlier this year focused only on avobenzone, a key ingredient in many of these products, in that it blocks UVA and UVB rays, that has been linked with allergic skin reactions.
The other chemicals also work as filters against ultraviolet A and B light rays from the sun.
For the new study, 48 participants were asked to apply one of four sunscreen products -- a lotion, aerosol spray, non-aerosol spray and pump spray -- to approximately 75 percent of their body surface area up to four times a day, at two-hour intervals. The researchers collected 34 blood samples over 21 days from each participant.
They found that geometric mean maximum plasma concentrations of all six active ingredients of these sunscreen products were above 0.5 ng/mL, the FDA's threshold for safety testing, on day 1 of the study, following a single application.
Although none of the study participants exhibited any significant health consequences from the presence of these substances in their blood, 14 did experience a rash.
The assessment was performed as part of the FDA's proposed rule change for sunscreen, issued in February 2019, which among other considerations called for increased safety testing for the active ingredients of many commercially available products. The rule change also recommends that sunscreen brands list active ingredients alphabetically on the front panel of their packaging.
"Given the recognized public health benefits of sunscreen use, FDA urges Americans to use sunscreens in conjunction with other sun protective measures, such as protective clothing," Woodcock said. "That's why as part of the proposed rule on sunscreen, the FDA requested additional information on active ingredients in sunscreen to evaluate their generally recognized as safe and effective status in light of changed conditions, including substantially increased sunscreen usage and evolving information about the potential risks associated with these products since they were originally evaluated. We look forward to sharing further updates on this important area of research."