There is persuasive evidence that each of the three main types of skin canc
er, basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and melanoma,
is caused by sun exposure. The incidence rate of each is higher in fairer
skinned, sun-sensitive rather than darker skinned, less sun-sensitive peopl
ed risk increases with increasing ambient solar radiation; the highest dens
ities are on the most sun exposed parts of the body and the lowest on the l
east exposed; and they are associated in individuals with total (mainly SCC
), occupational (mainly SCC) and non-occupational or recreational sun expos
ure (mainly melanoma and BCC) and a history of sunburn and presence of beni
gn sun damage in the skin. That UV radiation specifically causes these skin
cancers depends on indirect inferences from the action spectrum of solar r
adiation for skin cancer from studies in animals and the action spectrum fo
r dipyrimidine dimers and evidence that presumed causative mutations for sk
in cancer arise most commonly at dipyrimidine sites. Sun protection is esse
ntial if skin cancer incidence is to be reduced. The epidemiological data s
uggest that in implementing sun protection an increase in intermittency of
exposure should be avoided, that sun protection will have the greatest impa
ct if achieved as early as possible in life and that it will probably have
an impact later in life, especially in those who had high childhood exposur
e to solar radiation. (C) 2001 Elsevier Science B.V. All rights reserved.