Indoor UV tanning causes skin cancer

The U.S. Surgeon General should declare that indoor ultraviolet radiation tanning causes skin cancer, according to an article published today by the American Journal of Preventive Medicine.

Robert P. Dellavalle, MD, PhD, MSPH, associate professor of dermatology at the University of Colorado School of Medicine on the Anschutz Medical Campus, is the corresponding author of the article, which says there is enough evidence for the Surgeon General to clearly state that use of indoor tanning beds causes skin cancer.

Dellavalle and his co-authors use a common testing standard for causality, named after English epidemiologist Sir Austin Bradford Hill, to compare the case made in 1964 by the Surgeon General to link cigarette smoking to lung cancer to today's concerns about indoor ultraviolet (UV) tanning and skin cancer.

"As with tobacco and lung cancer, all Bradford Hill criteria except the experimental criteria are satisfied by the relationship between indoor UV tanning and skin cancer: tanning beds cause skin cancer," the authors write. "It is time now to announce this causality more openly."

The Bradford Hill criteria provide nine categories for evaluating the causal relationship between two factors. The authors report that for indoor UV tanning and skin cancer and for smoking and lung cancer, each fulfill eight of the nine criteria.

The remaining item, conducting "randomized controlled trials" on human subjects, cannot be tested because it would be unethical to expose humans to activities known to cause cancer, the authors write. According to the International Agency for Research on Cancer, which is part of the World Health Organization, UV tanning devices and tobacco smoke are classified as Group 1 carcinogens.

Based on the comparison with tobacco smoke and the health warning issued by the Surgeon General, the authors urge the Surgeon General to make a stronger statement than has been made so far regarding UV tanning devices.