Sunbed tanning poses risks for fair-skinned people to contract skin cancer, say researchers.
The Sun's short-wave UVB rays are well known to cause skin cancer, but the intense UVA radiation from tanning lamps could also present a risk for light-skinned individuals, a team from the United States, Poland and France reported in the journal Nature Communications.
In tests on shaved lab mice whose results should apply to humans too, UVA interacted with the pigment melanin to cause the most dangerous type of skin cancer, melanoma, they said.
"We think that this is a second pathway to melanoma," co-author Edward De Fabo, a photobiologist at the George Washington University in Washington, told AFP.
"You have the known UVB pathway (which causes) damage to DNA, and now we are saying that UVA interacting with melanin can cause damage to the DNA and cause melanoma."
Tanning lamps, said De Fabo, emitted up to 12 times the UVA intensity found in natural sunlight -- made up of about 95 percent UVA and five percent UVB.
"The early step in the tanning process is where the real risk lies," he suggested. "That is where the real damage tends to occur, those very early tans that you get when your skin is fair."
Asked whether he urged people to stay away from tanning salons, he said: "I would advise them definitely not to go."
New safety limits will have to be set, but the specifics required further study, he added.
Very dark-skinned people, like those of African origin, very rarely develop melanoma as their skins do not allow the Sun's ultraviolet (UV) radiation to penetrate the deeper levels of the epidermis.
The tans cultivated by fair people, in contrast, offered very little screening.
"A lot of people go to those sun-tanning parlours because they think when they get a base tan they are great to go out in the high intensity sunlight. That is just not the case," said De Fabo.