![]() 30+) and thus may be disadvantaged compared to most chemical sunscreens with higher SPF, although an SPF of 30 theoretically provides 97% UV protection. Mineral sunscreens typically have low advertised SPF ratings (e.g. CR also assesses sensory factors such as scent and skin feel, but does not specify how these or any of the primary criteria are weighted in determining their final score. UV-A protection is assessed by irradiating plastic plates covered with sunscreen and measuring the amount of UV-A transmission. The six spots are then exposed to different intensities of UV-B and examined one day later for erythema. 4 CR assesses SPF by applying sunscreen to six areas on participants’ backs followed by submersion in water for either 40 or 80 minutes, depending on the water resistance claims of the manufacturer. 3 We took a closer look at how CR evaluates sunscreens, and identified several potential flaws in their testing methods and scoring criteria which may disadvantage mineral-based products.ĬR rates sunscreens based on three primary criteria: sun protection factor (SPF) as a measure of UV-B protection, UV-A protection, and variation from the product-advertised and CR-determined SPF rating. ![]() 2 In one study, a zinc and titanium-based sunscreen completely attenuated induction of cyclobutene pyrimidine dimers and p53 in sun-exposed skin at 24 hours. A recent review of sunscreen-mediated prevention of DNA damage identified 10 studies demonstrating sunscreen efficacy however, none involved direct comparisons of chemical vs. 1 Ultimately, the ability of sunscreen to reduce skin cancer risk relates to prevention of UV-induced DNA damage. Additionally, some chemicals in organic sunscreens may cause contact dermatitis and harm marine life specifically, oxybenzone can react with chlorine, producing hazardous by-products that can concentrate in swimming pools and wastewater treatment plants. Such products, containing active inorganic ingredients zinc oxide and/or titanium dioxide, act by ultraviolet (UV) reflection and thus might be expected to be more efficient and stable than organic chemical sunscreens which act by UV absorption and can quickly become saturated or break down. Each year we are surprised that Consumer Reports (CR) magazine does not recommend to its subscribers a mineral sunscreen. ![]()
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