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I caddied at the Briar Hall Country Club, Briarcliff, New York (now, Trump National Golf Club Westchester) during my teenage years, where I learned to play golf. I was exposed to the sun for many hours each day, long before sunscreens became popular. Two years ago I had a basal cell skin cancer removed from my ear–more than sixty years after all that intense sun exposure.
I’ve been very fortunate, since skin cancer is the most common type of cancer in the United States, affecting more than 3.3 million people each year. Today, sunscreens are used all over the world to prevent sunburn by reflecting, absorbing, and/or scattering ultraviolet radiation.
Sunscreens are sold over-the-counter in the United States and are often applied in substantial amounts multiple times a day, sometimes starting in infants as young as six months of age. Ingredients primarily used as sunscreens are also found in some cosmetic products. Frequent skin applications can result in multiple grams of sunscreen applied to the skin daily. Skin is a well-established portal for drug absorption, but little is known whether the active ingredients in sunscreen are absorbed and thus exposed to the rest of the body.
Recently, researchers studied 24 healthy participants who used four commercially available sunscreens to see how the ingredients were absorbed through the skin. Six participants received one type of spray, and six got a second type of spray. Six received a lotion and six got a cream. They applied two milligrams of sunscreen per square centimeter of skin to 75 percent of body surface area four times per day for four days, and 30 blood samples were collected over seven days from each participant.
For all four sunscreens, concentrations exceeded the threshold established by the FDA for waiving toxicology studies for sunscreens. The most common adverse event was rash, which developed in one participant with each sunscreen.
Scientists have raised concerns about the safety of sunscreens – both on people and the environment. Sunscreen manufacturers have not demonstrated that the benefits of sunscreen application outweigh risks because sunscreens have not been subjected to standard drug safety testing. Appropriately designed trials have not been conducted to understand the optimal sunscreen dose needed to achieve a balance of risk and benefit when used to prevent skin cancer and melanoma.
In 2014, a public advisory panel convened by the FDA concluded that insufficient evidence existed to confirm the safety of many sunscreen ingredients and formulations. The panel also concluded that there was strong evidence that sunscreen prevents sunburn, precancerous actinic keratosis, and squamous cell cancer, but that evidence for melanoma prevention was not high quality. They said there was a need for long-term safety data, and acknowledged the challenges of performing effectiveness studies on a population level.
Most recently, the FDA proposed a rule that would reclassify 12 of the 16 ingredients commonly found in sunscreens no longer generally recognized as safe and effective, requiring manufacturers to provide product safety data. They also raised the maximum SPF value from SPF 50+ to SPF 60+; required more information on package labels; required that sunscreens with an SPF value of 15 or higher offer broad spectrum protection that covers both forms of exposure to ultraviolet light; and designated products that combine sunscreen with insect repellent as no longer generally recognized as safe and effective, and therefore requiring the submission of safety data.
While further studies about sunscreen ingredients are needed, these results do not indicate that you should refrain from the use of sunscreen. However, it probably would be a good idea to use the minimum effective amount, especially in youngsters who may be more vulnerable to the effects of sunscreen because of larger skin surface area relative to body weight. FDA officials have stated recently that “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 testing to determine the safety of that ingredient for repeated use.”
Another good idea would be to just stay in the shade! But if you’re a golfer or an outdoor enthusiast, who wants to do that? Use sunscreen, wear a hat, and watch for further developments as future testing results become available.
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