Determination of minimal erythema dose of ultraviolet in 127 volunteers from Urumqi region

Abstract

Objective To determine the normal range of minimal erythema dose (MED) for ultraviolet A (UVA) and B (UVB) in volunteers from Urumqi region.Methods One hundred and twenty-seven volunteers including healthy subjects and patients with noninflammatory skin disorders were enrolled in this study.SUV-1000 type UV simulator was used as the light source to determine MED of UVA and UVB in these subjects.Results These subjects included 48 persons with Fitzpatrick skin type Ⅲ,79 with Fitzpatrick skin type Ⅳ,51 males and 76 females.The median MED value for UVA and UVB was 38.1 J/cm2 and 31.8 mJ/cm2 respectively in subjects with skin type Ⅲ,59.16 J/cm2 and 48.00 mJ/cm2 respectively in subjects with skin type Ⅳ.Significantly lower median MED values of UVA (both P ＜ 0.01) and UVB (both P ＜ 0.05) were observed in the male and female subjects with skin type Ⅲ compared with those with skin type Ⅳ.The male subjects showed a significantly higher median UVA-MED value (59.16 J/cm2 vs.41.10 J/cm2,P ＜ 0.05),but a similar UVB-MED value (39.60 mJ/cm2 vs.35.55 mJ/cm2,P ＞ 0.05) compared with the female subjects.No significant difference was observed in the median value of UVA-or UVB-MED in subjects with skin type Ⅲ or Ⅳ between Han and Uygur nationality (all P ＞ 0.05).Also,no correlation was found in the median value of UVA-or UVB-MED with age or duration of outdoor exposure in the male or female subjects (all P ＞ 0.05).The lower reference limit was 33.38 J/cm2 for UVA-MED and 27.90 mJ/cm2 for UVB-MED in the population in Urumqi region.Conclusion Skin phototype may be an important determinant of MED.