When it comes to health matters, scientists rarely make statements that do not begin with “may.” But here is one. Excessive exposure to sunlight causes skin cancer! There’s no “may” about it. Neither is there any “may” about sunlight causing “photoaging,” the development of leathery wrinkled skin with long term sun exposure. And the damaging effects of sunlight are not restricted to farmers toiling in the fields or to sun-worshipping yuppies in quest of that alluring tan. Children and infants are also vulnerable. Luckily chemical protection is readily available. Uncertainties do, however, emerge when it comes to deciding on which specific chemicals to use.
There is also the question of whether children because of their more sensitive skin need special products. Some activist organizations claim that certain sunscreen ingredients are unsafe and blame regulatory agencies for not looking after the welfare of the public, while manufacturers profess that their products have been thoroughly tested for safety and efficacy. As usual, the public is left confused. Actually, when you blow away the superfluous blather emanating both from the alarmists and from industry, there is some simple advice to offer. You need to choose a product that offers protection both from UVB, the so-called burning rays, as well as from UVA, the longer, more penetrating waves that have been linked with skin cancer. Remember that the SPF number only refers to UVB. There is no need to look for anything higher than 30. That will filter out over 97% of all UVA. But you also need UVA protection. Look for avobenzone and zinc oxide, chemicals that are very effective at blocking long wavelength ultraviolet light. The sun protection product should be applied 15- 30 minutes before sun exposure and reapplied 15-30 minutes later and once more two hours later, although the fact is that nobody should be lying out there roasting for two hours no matter what. Forget terms like “waterproof.” Sun protection has to be applied each time after coming out of the water. And most important, enough lotion has to be applied. It takes 30 grams, or roughly a shot glass full for the body and half a teaspoon for the face. Most people apply way too little.
There is one more “may” about sunscreens that has been converted to fact. We no longer have to say that sunscreens may prevent skin cancer, we can say they do. A study in Australia, where skin cancer is a huge concern, involved 1600 subjects who were given sunscreen to use every day for four and a half years. They developed 40% fewer squamous cell cancers than a control group who just maintained normal skin care without being given specific instructions about the use of sunscreens. Remember only mad dogs and Englishmen go out unprotected into the noon day sun.