The Icelandic study of melanoma trends by Héry et al. in this issue of the Journal (Am J Epidemiol. 2010;172(7):762-767) is a fascinating analysis of an ecologic association. The authors noted a sharp increase in melanoma incidence that appeared to lag a few years behind the increased prevalence of sunbeds in Iceland. Caution, however, must be exercised in interpreting the data because of the lack of understanding of emissions of ultraviolet radiation from sunbeds and the ecologic nature of the data.