Ultraviolet absorption of prescription sunblocks in Mexico

An appropriate sunscreen should provide high and broad ultraviolet protection both for the B and A range. The objective was quantify the ultraviolet absorption spectrum in sunscreens available for medical prescription, and analyze its relationship with the labeled Sun Protection Factor (SPF). Thirty-nine sunscreens were analyzed in vitro using ultraviolet spectroscopy following exposure to simulated solar irradiation. Fifty-six percent of sunscreens absorbed 90% or more of ultraviolet radiation. Seventy-five percent (n = 34) absorbed more than 95% of ultraviolet B radiation, and 46% (n = 18) more than 90% of ultraviolet A. There was no significant association between ultraviolet absorption and SPF. We were unable to estimate ultraviolet absorption only by its SPF. Protection differed considerably among products with similar SPF. Our study highlights regulation deficiencies in marketing practices of these products.