Repeated ultraviolet exposure affords the same protection against DNA photodamage and erythema in human skin types II and IV but is associated with faster DNA repair in skin type IV.

We have investigated the photoprotective properties of induced pigmentation using erythema and epidermal DNA photodamage as endpoints. Previously unexposed buttock skin of 12 young, healthy adults (six skin type II and six skin type IV) was exposed daily (Monday to Friday) for 2 wk (days 1-12) with 0.65 minimal erythema dose of solar simulated radiation.