The Influence of Non-UV Wavelengths of Light on Skin: What Constitutes a Healthy Level of Exposure Particularly in Relation to Melanoma?

Abstract

We live with solar radiation from birth to death and have since the emergence of life on earth. Why then does skin cancer diagnosis remain so disturbingly high in Australia? Part of the problem is the majority of the population are of Northern European ancestry. Moving closer to the equator on mass we have carried with us a polymorphic melanocortin receptor gene on our melanocytes responsible for an incomplete tanning response. We attempt to protect ourselves with clothing and creams or remain indoors but this does not seem to be stemming the tide. Occupation, recreation or both drive us outside and into the sun. We need to be more successful at negotiating the potentially harmful effects by relooking at solar radiation and instead of focusing on the most harmful wavelengths look at the overall effect of the whole spectrum. We also need to re-examine our behaviour and exposure patterns. Prolonged periods indoors under artificial light punctuated with short bursts of intense irradiation is maladaptive. Creams aim to block the ultraviolet component, ignoring 90% of solar photons, the protective effect is incomplete, yet their use encourages more prolonged exposure. Protective behaviours are necessary for the most sensitive skin types but they are still at risk. For the rest of the population evolutionarily developed natural protective mechanisms can be employed. Regular moderate sun exposure, below the burn threshold, ideally aimed at early morning or late afternoon. Augmented with clothing, hats and creams with an appreciation of the incomplete protective effect of these measures.