Measurements of the anatomical distribution of erythemal ultraviolet: a study comparing exposure distribution to the site incidence of solar keratoses, basal cell carcinoma and squamous cell carcinoma

Measurements of anatomical UV exposure distribution were made using miniaturized polysulfone dosimeters over a four year period between 2005 and 2008 in Toowoomba, Australia (28 degrees S, 152 degrees E). Anatomical UV exposures were expressed relative to the horizontal plane ambient UV. The UV exposures were compared with existing data detailing the anatomical distribution of basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and solar keratoses (SK). Surface UV exposures to unprotected skin surfaces have been presented for each of the face, neck, arm, hand and leg assessing a total of 1453 body sites (2491 measurements). Measured exposures are presented for the human facial region to a resolution of 5 mm. The median anatomical UV expressed relative to the horizontal plane ambient UV for each of the face, neck, forearm, hand and leg regions of the body varied from 26%, 23%, 13%, 30% and 12% respectively in the 0 degrees-30 degrees SZA range; 39%, 36%, 17%, 35% and 23% in the 30 degrees-50 degrees SZA range; and 48%, 59%, 41%, 42% and 47% in the 50 degrees-80 degrees SZA range. Detailed positions of UV exposure measured over the face, neck, arm, hand and leg were more closely related to NMSC incidence data for the face and upper limbs. Further analysis with existing facial BCC and SK density data did not however show a direct relationship with the measured UV exposures highlighting the importance of other factors influencing the causation and localisation of facial NMSC.