Tanning beds and ultraviolet radiation cause cancer and have been moved up to the highest risk category by international cancer experts.
The new classification means tanning beds and UV definitely cause cancer in humans, just as tobacco smoke, the hepatitis B virus and mustard gas do.
The International Agency for Cancer Research or IARC, the World Health Organization's cancer wing in Lyon, France, updated the level based on research published online Wednesday in the medical journal Lancet Oncology.
"People need to be reminded of the risks of sunbeds," said Vincent Cogliano, one of the study's authors. "We hope the prevailing culture will change so teens don't think they need to use sunbeds to get a tan."
Until now, tanning beds and UV were considered "probably carcinogenic to humans."
Experts upgraded the level after a comprehensive analysis of about 20 studies concluded that the risk of skin melanoma is increased by 75 per cent when people started using tanning beds before age 30.