The Geography of Malignant Melanoma in the Nordic Countries: The Implications of Stratospheric Ozone Depletion

ABSTRACT

Malignant melanoma is a disease for which exposure to ultraviolet radiation in sunlight is probably an important risk factor. The high latitudes and low intensity of UV radiation in the Nordic countries might therefore be expected to produce a low risk. However, this is not the case with the Nordic countries having amongst the highest rates in Europe and a sustained increase over time. Concern has been heightened by the prospects of increased exposure to UV as a result of stratospheric ozone depletion which is expected to be greatest at high latitudes This study analyses the geographical pattern of melanoma incidence within Scandinavia using data for counties from the Nordic Cancer Atlas. Regression analysis shows that differences in levels of affluence (and associated patterns of behaviour) account for some of the geographical variations in melanoma risk. Significant national differences in risk are also revealed, possibly as a result of genetically determined differences in susceptibility to exposure to UV. However, it is shown that variations in estimated local levels of UV flux are the dominant influence on the geographical pattern of melanoma incidence within Scandinavia. It can therefore be expected that an increase in UV levels as a result of stratospheric ozone depletion will lead to an increase in melanoma. From the regression model it is estimated that a 10% increase in UV would be associated with a 13.7% increase in melanoma. This means that any major depletion of ozone could dramatically worsen the melanoma epidemic in the Nordic countries.