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Most parents, you might think, now apply sunscreen to their children when they are to be exposed to bright sunlight. It is perhaps, therefore, surprising that supplying extra sunscreen to parents in Canada (Richard P Gallagher, and colleagues.Journal of the American Medical Association2000;283:2955–60) apparently reduced the number of melanocytic naevi which developed in their children.
A total of 458 Vancouver schoolchildren aged 6–7 or 9–10 years entered the trial and 309 completed it. Parents randomised to the treatment group were supplied with a broad spectrum sunscreen (SPF 30) and advised to apply it to exposed areas whenever the child was to be exposed to sunlight for 30 minutes or more. Parents in the control group were given no sunscreen and no advice (though many of them used sunscreen on their children).
Over three years of follow up the mean number of new melanocytic naevi acquired was 24 in the sunscreen group and 28 in the controls. Protection was greater in freckled children; it was estimated that supplying sunscreen reduced the development of new naevi in freckled children by 30–40%.
The hope, of course, is that use of sunscreen will protect against the later development of malignant melanoma, but that remains to be shown.