
Although many people still desire a suntan, we now understand just how damaging exposure to the sun can be. Repeated sun exposure greatly increases skin wrinkling and may even lead to skin cancers. Adding wrinkles while trying to improve appearance is obviously counterproductive and has led to the popularity of so-called sunless tanning products. The active ingredient in sunless tanners is the compound dihydroxyacetone (DHA). DHA is approved by the Food and Drug Administration for use in externally applied cosmetics intended to impart color to the skin. A three-carbon sugar, DHA reacts with amino groups in the proteins of the top layer of the skin, called the stratum corneum (SC). The first step is known as the Maillard reaction, the same process that leads to the caramelization of sugars and the browning of bread. Sunless tans do not absorb ultraviolet light in the range that causes sunburn. They therefore do not protect ...