Henry W. Lim, MD
In a commentary published online in the Journal of the American Academy of Dermatology (JAAD), dermatologists Henry Lim, Steven Wang and Stephen Dusza [1] say there is no evidence that retinyl palmitate (vitamin A palmitate) [2] in sunscreens causes cancer.
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“Earlier this year, the Environmental Working Group (EWG) [3] issued a health warning that sunscreens containing retinyl palmitate could pose a cancer risk,” said dermatologist Henry W. Lim, a fellow of the American Academy of Dermatology, chairman of the department of dermatology at Henry Ford Hospital in Detroit. “This warning garnered significant media attention and caused considerable confusion among the public. Our report should help dismiss the misinformation that sunscreens are not safe, as sunscreens are vitally important in reducing your risk for skin cancer, not causing it.”
Authors of the commentary explain that although retinyl palmitate was selected for testing by the National Toxicology Program (NTP), mere selection does not mean that the chosen compounds are dangerous or unsafe. They say that retinyl palmitate was mainly selected because of its widespread use in cosmetic and sunscreen products. Many common ingredients, such as aloe vera, nanoscale titanium dioxide, and zinc oxide are currently under review by the NTP.
No “conclusive evidence”
The Environmental Working Group’s concerns were mainly based on a succession of eight in vitro studies performed since 2002 demonstrating that retinyl palmitate can produce free radicals, which can disrupt cell function. According to Dr. Steven Q. Wang, co-author of the commentary, these non-human studies are too far from the real conditions of use to be biologically relevant. “For example, when a sunscreen with retinyl palmitate is applied to the skin, a number of antioxidants work together to alleviate the risk of free radical formation seen in these in vitro experiments,” he said.
Dr. Wang and his team also reject the results of a large animal study testing conducted by the NTP whether hairless and albino mice developed tumours sooner when coated in retinyl palmitate versus a placebo cream. In particular, they argued that “at this time, the findings have not been published in peer-reviewed literature,” and that “mice in the NTP study are highly susceptible to the effects of UV radiation and can develop skin cancer or other skin abnormalities within weeks of UV exposure, even in the absence of retinyl palmitate.”
Although there are no published human studies on the potential of retinyl palmitate or other retinoids to cause cancer, the commentary concludes that observations from decades of clinical practice do not support the notion that retinyl palmitate in sunscreen causes or promotes skin cancer.
“On the contrary, years of research suggests that retinoids are helpful in reducing your risk for skin cancer,” said Dr. Wang. “People should continue vigilantly using sunscreens along with other sun-safe practices – such as limiting sun exposure, seeking shade, and wearing sun-protective clothing, hats and sunglasses – to reduce the risk of skin cancer and premature aging.”
EWG refutes critiques
The Environmental Working Group has strongly criticised the conclusions of the commentary. The public action group, said it found “numerous flaws and misleading arguments” in the commentary published in the JAAD, “along with undisclosed industry affiliations by two of the three authors.”
“Their fragmentary analysis of a government study exonerates an ingredient used by companies for whom they have done paid consulting,” said Jane Houlihan, EWG’s senior vice president for research.
