Statistical study of individual variations in sunburn sensitivity in 303 volunteers without photodermatosis.

Variations in individual sunburn sensitivity have been studied using erythema as the photobiologic criterion. The minimal erythema dose (MED), the minimal dose necessary to elicit an intense erythema (MED++), and an edema (MOD), were determined by Saidman's method. The irradiation was performed with a 2,500-W xenon arc solar simulator fitted with a water filter and WG 305 Schott filter. The high correlation between MED, MED++, and MOD and the existence of saturation phenomenon confirm that determination of MED is the best photobiologic criterion. The average MED and the pathologic threshold for total light spectrum irradiation are, respectively, 889 mJ/cm2 and 347 mJ/cm2. A statistically significant variation in MED as a function of age, sex, complexion, eye color, hair color, and Fitzpatrick skin type has been established. Finally, complexion has been shown to be the best clinical criterion for the characterization of sunburn sensitivity and a new classification of the epidermis for UV therapy and artificial photoprotection is proposed.