Skin cancer risk affected by ultraviolet solar irradiance in Arica, Chile

The present study analyzed the risk of skin cancer due to ultraviolet erythemal irradiance (UVery) in Arica, Chile, using measurements of the solar ultraviolet index (UVI) between 2006 and 2011. The daily maximum value by biometer Yankee Environmental Systems (YES) solar ultraviolet B (UVB)‑1 was measured between 2007 and 2012, and seasonal variations were clearly observed, with higher UVI levels during the summer when UVI usually reached extreme values of >11. The maximum UVI value was 15.6 in the summer of 2008 and the minimum was 2.2 in the winter of 2008. The UVI mean values that were collected monthly at noon between 2006 and 2010 fluctuated between 13 and 6, and reached higher values in January and lower values in June and July. Thus, a seasonal UVI response was observed during the two seasons. The accumulated UVery/day was calculated between September 2006 and 2007, the time when Arica normally receives the highest UVI levels. It was also noted that 60% of the days in September demonstrated values of >3.41 kJ/m2/day, while 3.3% of cloudy days had values of <2.0 kJ/m2/day. The mean value of UVery during 2007 was 3.23 kJ/m2/day and the variation was 1.9‑4.6 kJ/m2/day. These UVery values were several times higher than the minimal erythemal doses (MEDs) corresponding to the skin types most frequently observed in Chile, skin types III and IV. The MED for skin type IV was 0.60 kJ/m2. The results demonstrated that the skin cancer rate was increased due to the fact that individuals from Arica are exposed to several times more UVery than the MED for their skin type during the spring and summer seasons.