Assessment of skin types, skin colours and cutaneous responses to ultraviolet radiation in an Asian population

Ninety normal individuals were included in this study on skin types, skin colours and cutaneous responses to ultraviolet radiation. Skin types were recorded using Fitzpatrick's classification, skin colours were measured using the Minolta Chromameter CR-300, and cutaneous responses to UV radiation were measured in terms of minimal erythema dose (MED) to UVA, UVB and the immediate pigment darkening dose to UVA (IPDDA). Skin colour measurements were taken from the right cheek to represent facultative skin colours, and from the buttock to represent constitutive skin colours. The colours measured were expressed by the L*a*b colour space. Skin types and some colour parameters (L and b from covered parts of body) correlated fairly well with the minimal erythema doses (MED) to UVA and UVB. Skin colour measurements are more objective than skin type assessment and could be better markers of photosensitivity. However, there is still considerable overlap in MEDs for persons with different skin colours, and further studies of these parameters are warranted. Our MEDs are higher than other reports on similar skin types and skin colours. This could be due to differences in methodology, genetic make-up or acclimatization from chronic sun exposure. This illustrates the importance of local controls for each institution dealing with photosensitive disorders.