Indoor tanning almost doubles the risk of dangerous melanoma skin cancer, and the more hours spent tanning, the greater the risk, according to a new study.

Those who used indoor tanning devices were 1.74 times as likely to develop melanoma as those who did not. Frequent users - who had more than 100 sessions or 50 hours of indoor tanning over 10 years - were at 2.5 times the risk of non-users, the study found.

That correlation, called a dose response, “is very important for helping to support that this is a causal influence,” said DeAnn Lazovich, a University of Minnesota epidemiologist who is lead author of the study, published online recently in Cancer Epidemiology, Biomarkers & Prevention.

Last year, the International Agency for Research on Cancer, part of the World Health Organization, classified tanning beds as carcinogenic to humans, and the United States Food and Drug Administration is considering revising requirements for tanning beds and strengthening warning labels about the risks.

The new study compared 1,167 Minnesota residents who had an invasive melanoma diagnosis from 2004 to 2007 with 1,101 healthy individuals.


RONI CARYN RABIN