Influence of environmental factors on facial pigmented spots: Epidemiological survey of women living in the northern and southern regions of Japan.

BACKGROUND

Several epidemiological studies have been conducted to understand the relationship between environmental factors (including chronic sun exposure) and clinical signs of pigmented spots. However, no quantitative analysis has focused on the adverse effects of the detailed features of pigmented spots, including their color intensity, size, and number on the cheek. This study was performed to elucidate the adverse effects of environmental factors on clinical signs of pigmented spots.

METHODS

We conducted an epidemiological survey of 102 Japanese women in 2 regions of high and low sun exposure (southern and northern regions, respectively). Using image analysis of high-resolution digital facial photographs, individual pigmented spots were quantified according to color, size, and total number on the cheek. Each indicator was then compared between the groups.

RESULTS

For the number of pigmented spots on the cheek, the age-related increase curve showed a large slope in the southern group. For the size of pigmented spots, no significant difference was found between the two groups, and large pigmented spots were observed on the cheek even in the northern group. For the color intensity of the spots, the southern group showed a marked age-related change; among older subjects, the pigmented spots were significantly darker in the southern than northern group.

CONCLUSION

Our results may indicate that environmental factors, including chronic exposure to sunlight, mainly increase the number of pigmented spots and darkening of these spots. However, the occurrence of large pigmented spots may be related to intrinsic factors represented by heredity rather than environmental factors.