There is no such thing as a safe tan, leading scientists claimed today.
Researchers found than any exposure to the sun can potentially lead to skin cancer.
The team from George Washington University say their research could change medical advice.
No such thing as a safe tan: researchers say any exposure to sunlight can be dangerous
'This is the first time that UV-induced melanin formation (tanning), traditionally thought to protect against skin cancer, is shown to be directly involved in melanoma formation in mammals,' said Professor Edward De Fabo, who led the study.
'Skin melanoma is the most lethal of the skin cancers.
'Our study shows that we were able to discover this new role for melanin by cleanly separating UVA from UVB and exposing our experimental melanoma animal model with these separated wavebands using our unique UV light system designed and set up at GW.
Skin cancer is one of the most common cancers in the UK and the number of people who develop it is increasing.
The research echoes the advice of dermatologists.
'Dermatologists have been warning for years there is no such thing as a safe tan and this new data appears to confirm this,' said Professor De Fabo.
Suntanned tennis fans at Wimbledon - scientists now say that any exposure to the sun could be harmful
The research is published in the journal Nature Communications.
The team used a mammalian model to investigate melanoma formed in response to ultraviolet wavelengths.
The researchers also shed new light on the dangers of sunbeds.
'Also new is our discovery that UV induction of melanin, as a melanoma-causing agent, works when skin is exposed only to UVA and not UVB radiation,' said Professor De Fabo.
'This is especially important since melanoma formation has been correlated with sunbed use as many epidemiological studies have shown.
'One possible reason for this is that tanning lamps are capable of emitting UVA radiation up to 12 times, or higher, the UVA intensity of sunlight at high noon.
'Melanin plus UVA is known to cause photo-oxidation, a suspected, but still to be proved, mechanism for the formation of melanoma as we describe in our study," De Fabo said.
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