1999 Volume 9 Issue 6sup Pages 136-142
In order to better understand the effect of chronic sun exposure on facial skin photo-aging andto identify the factors affecting it, we planned a study in two areas in Japan, Akita andKagoshima, which correspond to the low and high sun exposure environments, respectively. Asa first step, we conducted a pilot study in the two areas, examining 195 subjects.Hyper-pigmentation and wrinkling were measured with a high-resolution digital video imaging system.As expected, people in Kagoshima had darker skin, higher visual grades of facial hyper-pigmentation, and more facial wrinkles than people in Akita, reflecting the difference of UVexposure levels in the two areas. Both the grades of hyper-pigmentation and number of wrinklesincreased in a roughly linear fashion with the advancement of age. On the other hand, the effectof gender was different in those two skin photo-aging parameters. Women had higher hyper-pigmentation grades (P=0.012) and less wrinkles (P=0.004) than men. Interestingly, post-menopausal women had higher grades of hyper-pigmentation than pre-menopausal women.Neither sun exposure index for darkness nor wrinkling showed any significant differences bymenopausal status. In this pilot study, we collected information on various factors, including life-styles. The results of detail analysis will be presented elsewhere. In the present analysis, wefound that the grade of hyper-pigmentation was not related to total hours spent outside in life butwas affected by various factors, including toe-nail zinc levels. On the other hand, the number ofwrinkles was significantly related to total hours spent outside in life.The most important risk factors of non-melanoma skin cancer are chronic sun exposure, ageand male sex. All of them are strongly related to higher levels of UV exposure. The present studyconfirmed that chronic sun exposure, age and male sex were strong risk factors of the wrinklenumber. The number of wrinkles was significantly related to total hours of sun exposure in life, increased in a roughly linear fashion with the advancement of age, and was larger in men than inwomen. In epidemiological studies of UV-related skin cancer, the number of wrinkles, which canbe easily measured with a high-resolution digital video imaging system as shown in this study, may be a good marker of total sun exposure in life. J Epidemiol, 1999; 9 : S136-S142.