I just attended a half-day educational session on dermatology (skin disorders), which included an extensive review of skin cancers and their treatment. Melanoma incidence continues to increase. Melanomas are serious and aggressive cancers that metastasize widely and may readily kill you. Exposure to UV radiation in tanning booths, as on the beach, is with little remaining question causative for the DNA mutations that provoke melanomas.
If dying from excess UV exposure were not enough deterrent, consider that regular UV exposure accelerates skin aging. The product of that premature skin aging may take two decades or more to develop, but it is most real. I have noted the “prune lady” skin prevalent among middle-aged females who sunned heavily, with thinning and heavy wrinkling much more appropriate to an 80-year-old cowboy. It is most unattractive, quite sad, essentially irreversible, and a virtual guarantee of needing intense contact with dermatologists and dermatological surgeons in your middle age.
The New York Times, Jan 10, 2015 just had an excellent piece on tanning beds (Warning: That Tan Could Be Hazardous), which elaborates on the dangers. Tanning salons are stupid and dangerous places to frequent.