Availability of Vitamin D Photoconversion Weighted UV Radiation in Southern South America

DIAZ, S.; VERNET, 'M.; PALADINI, A.; CAMILION, C.; FUENZALIDA, H.; DEFERRARI, G.; BOOTH, C.; CABRERA, S.; CASSICCIA, C.; DIEGUEZ, M.; LOVENGREEN, C.; PEDRONI, J.; ROSALES, A.; VRSALOVICH, J.

Encuentro; Primera Reunion de Fotobiologos Argentinos, Junio 2-4, 2011, INIFTA, La Plata,; 2011

Ultraviolet Radiation (UVR) plays a key role in several biological functions, including human health. The relationship between vitamin D production and UVR is well known. There is also evidence relating low levels of vitamin D with certain internal cancers, mainly colon, breast and prostatic. Several epidemiological studies have shown an inverse relationship between these types of cancer and latitude, in accordance with the UVR latitudinal gradient. Given the latitudinal extension of Chile and Argentina (from approximately 24 to 55 degrees South), there is a wide range of exposure situations where the inhabitants of the southern regions would be exposed to low UVR. In this study, vitamin D production weighted-irradiance in eight stations distributed between S.S. de Jujuy (24.17°S, 65.02°W) and Ushuaia (54° 50´S, 68° 18´W) were analyzed for maximum daily values, and daily and annually integrated values. Radiation levels were combined with skin type and body exposure area to evaluate the latitudes at which population was at risk of low Vitamin D levels. It was observed that irradiances in southern regions were much lower than in central and northern ones, being below the minimum required for vitamin D production during part of the year. Annual integrated irradiance in Ushuaia and Punta Arenas (55o S and 53o respectively) were about half than stations further north, near 30oS, and even lower, if compared to S.S de Jujuy. The balance between Vit D synthesis and erythema was estimated by determining the best time of day for optimum exposure.