The study also found all types of ultraviolet radiation caused worrying mutations in mice, which they say is proof that radiation is carcinogenic. The new classification means tanning beds and ultraviolet radiation are definite causes of cancer, along with tobacco and the hepatitis B virus. The research is published online in the journal Lancet Oncology.
A European tanning bed association maintains there is no proven link between the responsible use of sun beds and skin cancer. It said most users of tanning beds use them less than 20 times a year.