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In 1999, the authors began recruitment for a randomized controlled intervention trial aimed at preventing melanocytic nevi (moles) by minimizing sun exposure through the use of sun-protective clothing. The study involves 652 Caucasian children (75.6% response) aged 0-35 months from 25 child-care centers (n = 13 intervention and n = 12 control) living in the high-solar-irradiance environment of Townsville, Queensland, Australia. Children attending intervention centers wear investigator-provided garments made from fabrics with ultraviolet protection factors rated very good to excellent. Control centers continue to offer usual care. Three-year follow-up of all children will be completed in 2005. The main outcome measure is the number of new melanocytic nevi. At baseline, the two groups were similar with respect to nevi, phenotype, age, demographic characteristics, sun-protection habits, and history of sun exposure, except that more children from control versus intervention centers (2% and 0%, respectively; p = 0.006) had experienced painful sunburn with blistering. Higher melanocytic nevus counts were associated with more time spent outdoors and a history of sunburn, while sunscreen use, particularly during the mild winter months, appeared to have a protective effect. These findings further substantiate the hypothesis that nevus development in young children is related to sun exposure.

Sunlight is the principal environmental cause of melanoma and has also been implicated in the pathogenesis of melanocytic naevi. Epidemiological evidence indicates that childhood is a period during which melanocytes are susceptible to the effects of sunlight, yet little is known about the development of naevi in infancy. We conducted a survey of child-care centres to document the prevalence and anatomical distribution of melanocytic naevi among 193 young children aged 1-3 years in Brisbane, Australia (latitude 27 degrees S). Naevi were counted on all skin surfaces except for the scalp, buttocks and genitalia. Overall, almost 90% of children in the study sample had at least 1 naevus of any size, and more than 30% of children had 10 or more naevi. Total naevus counts ranged from 0 to 45 and were strongly determined by age. When taken together, naevus densities were highest on exposed body sites such as the face and limbs; however the density of large naevi (> or = 5 mm) was significantly higher on the trunk than on the face, neck and ears. These data support the concept that melanocytic neoplasia commences early in life and that naevus evolution is influenced by the anatomical site of the target cell., (Copyright 2003 Wiley-Liss, Inc.)

Queensland, Australia, has the highest rates of melanoma in the world and Queensland children have the greatest numbers of melanocytic naevi, the strongest risk factor for melanoma. Although both melanoma and naevi are broadly related to sun exposure in childhood, the relation to individual exposure early in life is difficult to study retrospectively in adults. We surveyed 506 children aged 1-6 years who had been born in Townsville, North Queensland. Sun exposure was assessed by questionnaire and melanocytic naevi were counted using a standard international protocol. Very high counts (upper quarter) of melanocytic naevi were significantly associated with sun exposure of more than 4 hours per day (adjusted relative risk ratio 3.29; 95% Cl 1.12-9.69), and with a history of sunburn (1.89; 1.11-3.21). Melanocytic naevus counts increased with age, light skin reflectance, and freckling. With exposure to intense ultraviolet light in Townsville, children develop melanocytic naevi early in life and in large numbers. We found that both acute and chronic exposure to sun are associated with their development.