Solar ultraviolet radiation exposure and human health in South Africa: finding a balance.

In considering the likelihood of South Africa (SA) attaining the 2015 Millennium Development Goals, many health issues require urgent attention. The adverse effect of insufficient or excessive exposure to solar ultraviolet radiation (UVR) may exacerbate an already stressed public health service. These concerns become important when considering climate variability and patterns of behaviour. Latitude and altitude are significant in determining how much solar UVR reaches the Earth's surface. SA spans 15° of latitude (~22°S to 34°S), its altitude differs from sea level to 3 482 m (average plateau (Highveld) altitude 1 200 m), and the Highveld and other parts of the country have relatively cloud-free skies. SA thus has relatively intense solar UVR levels and, consequently, an increased risk of associated adverse health effects. Sun exposure also has positive health effects including the promotion of vitamin D production. A balance must be struck to allow sufficient solar UVR exposure to attain adequate vitamin D levels, while minimising the negative aspects. This balance is not straightforward as it varies from person to person and depends on factors such as skin type, clothing, and the timing of outdoor activities. Excessive sun exposure is detrimental to individuals of all ethnicities and skin types. Sunburn is a common acute effect, particularly in those with fair skin, and sun exposure is the major environmental risk factor for skin cancer. The carcinogenic and immunosuppressive effects of chronic UVR exposure induce changes that result in the cutaneous cancers – melanoma, squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). The lifetime risk of melanoma is estimated to be 60 times lower among dark-skinned individuals compared with those of fair skin. BCC is the most frequent type of skin tumour in whites, and the rarest in blacks. The last report from the National Cancer Registry (2000-2001) described an incidence of 20 000 new cases of skin cancer per year in SA, based on pathology reports. This is undoubtedly an underestimate, as most SCCs and BCCs are under-reported and/or not recorded or biopsied. SA's melanoma incidence is reported to be among the highest in the world (69 new cases per 100 000 whites in 2009) and roughly similar to that of Australia and New Zealand, with 700 associated deaths per annum. 1 Even with limited available data, the incidence of skin cancer in SA appears to be increasing. Data are urgently required to monitor this situation; the reinstatement of …