More young people are being diagnosed with skin cancer, a consultant dermatologist has claimed.
There are calls for the tanning industry to be properly regulated
Dr Sharon Blackford from Singleton Hospital in Swansea, said she was treating people in their 30s for skin cancers more commonly found in the old.
The popularity of unregulated tanning salons, many of which are unstaffed, are being linked with the rise.
But a leading sun bed chain denied that under-age customers were using their coin operated salons.
Dr Blackford said she was seeing more people with the non melanoma types of skin cancer which used to be predominantly a problem in elderly people.
"We're seeing people in their 30s which is definitely a bad sign," she says on Eye on Wales, Radio Wales' current affairs programme, broadcast on Monday.
"When you've got skin cancer at that age then you are going to go on getting more and more of them unfortunately.
"I know certainly in Swansea of teenagers as young as 13 and 14 year going on sun beds, now I think that is disgraceful."
Labour MP for Swansea East, Sian James, has put forward a Commons early day motion calling for regulation of the unmanned section of the industry.
"I was shocked when I realised young people were accessing for very little money, coin operated salons and the nub of the problem is that there is no staff there," she said.
Consol Suncenter, a European tanning chain with around 80 coin- operated salons in the UK, has refuted the claim that teenagers use their salons.
"Having operated here for the last 10 years we have not found evidence of under age customers using Consol studios and if we for a minute thought that was the case we would be sharing Sian James' concern, but we'd like the evidence," said spokesperson Sam Kirby.
The UK's Sunbed Association represents 20% of the industry and believe that coin-operated salons should be closed down.
The association has no legal powers to enforce an under-16s rule amongst its members, who are currently self-regulating.
"They (Consol Suncenter) are not allowed membership of The Sunbed Association because they could not meet the requirements for the code of practice, one of which is that the sun bed's have to be used under the supervision of appropriately trained staff," said the association's chief executive Kathy Banks.
The British Medical Association and Cancer Research UK called for a ban on under-16s using tanning salons in 2004.
Andrew Newton Lee, who starred in the teen soap Hollyoaks, was a frequent sun bed user until he developed skin cancer.
"My doctor told me for a guy who is 23 to have two malignant melanomas in their legs is highly unusual," said the actor who is now based in Los Angeles.
"Sunbed use is a very real and true risk and that's what people need to understand. All I do is look down and see these big scars and think, wow I had a lucky escape."