It has never been proven that tanning beds are any worse than the sun. Being in a family of tanning salon owners and having been managing one for 6 years I can tell you that MODERATION is the key. There is no need to be extremely dark. Some people are not comfortable with their skin color, some people are actually told to come to cure acne and oily skin problems.
News reporters have come in for information regarding specific bed types, bulb types, lotions, session times, etc...
THe only 2 reports I have heard was that the Tanning bed was more harmful because of its "quick" tan nature...
The other that Outdoor tanning is worse because of the depletion of the Ozone layer and not being able to control what type of UV exposure you receive.
Tek