Does Vitamin A (most commonly used as retinyl palmitate) cause skin cancer?
Retinyl palmitate has been added to over-the-counter sunscreens which are marketed as preventing the damaging effects of sun exposure on the skin: premature aging and skin cancer. Last month a widely touted study was published which purports to show that this agent can cause skin cancer! What is this all about? Do we all need to stop using retinyl-palmitate-containing sun screens?
In 2000 the Food and Drug Administration (FDA) authorized a study to look at the cancer causing potential of topical Vitamin A derivatives. A study was commissioned that studied mice given various doses of retinyl palmitate and various amounts of ultraviolet light (simulating sun exposure). There was a clear relationship between retinyl palmitate and skin cancer (squamous cell carcinomas) at doses that simulated human use. On that basis the Environment Working Group issued a strong report calling retinyl palmitate a carcinogen. This conclusion has come under brisk attack because what happens in mice is often not applicable to humans. I know of no plans on the part of drug companies to take retinyl palmitate out of sun screens, but the issue is not settled.
The United States Senate has weighed in. Senator Charles Schumer (D, NY) last summer stated on the floor of the Senate:
With the recent reports suggesting a possible link between skin cancer and a common chemical found in sunscreens, the FDA must act now to protect consumers in New York and across the nation. Summer is here, people are soaking up the sun and the FDA needs to immediately provide guidance and reassurance to consumers. When it comes to the health and safety of the public, there is no room for delay.
So far the FDA hasn’t commented further. Clearly there is value in sun screens in preventing sun damage; whether the addition of retinyl palmitate is a step in the wrong direction remains to be determined. In the meantime it might be prudent to buy sun screens that do not contain retinyl palmitate.
How about tanning booths? The answer is pretty simple. Tanning booths cause malignant melanoma, the deadliest form of skin cancer. The largest analysis of this question (Cancer Epidemiol Biomarkers Prev 2005;14:562-566) analyzed many smaller studies and showed a strong statistical correlation between the use of tanning booths and the subsequent development of melanoma. Other studies have shown a very high prevalence of tanning booth use among female adolescents (30-40%), at an age when sun exposure is most strongly correlated with later melanoma. There is no basis in the published medical literature for the common misconception that tanning booths are safer than sun exposure.
The take-home message? Stay tuned about retinyl palmitate; look at the side of your sun screen tube to see what is in it. Avoid tanning booths. Amazingly, health clubs have them. There is nothing healthy about them.