LONDON - International cancer experts have moved tanning beds and ultraviolet radiation into the top cancer risk category, deeming both to be as deadly as arsenic and mustard gas.

A new analysis of about 20 studies concludes the risk of skin cancer jumps by 75 percent when people start using tanning beds before age 30. Experts also found that all types of ultraviolet radiation caused worrying mutations in mice, proof the radiation is carcinogenic. Previously, only one type of ultraviolet radiation was thought to be lethal. The new classification means tanning beds and ultraviolet radiation are definite causes of cancer, alongside tobacco, hepatitis B and chimney sweeping, among others.

The research was published online in the medical journal Lancet Oncology on Wednesday, by experts at the International Agency for Research on Cancer in Lyon, the cancer arm of the World Health Organization.

Most lights used in tanning beds give off mainly ultraviolet radiation, which cause skin and eye cancer. As use of tanning beds has increased among people under 30, doctors have seen a parallel rise in the numbers of young people with skin cancer.

In Britain, melanoma, the deadliest kind of skin cancer, is now the leading cancer diagnosed in women in their 20s. Normally, skin cancer rates are highest in people over 75.

Previous studies found younger people who regularly use tanning beds are eight times more likely to get melanoma than people who have never used them.