"Any time you pierce the skin, you're at risk of something," said Kathleen Ciampi, executive director of the Society of Permanent Cosmetics Professionals. "It's an invasive procedure .... A tattoo is essentially a colored wound."

But, Ciampi said, by and large, the industry is careful to minimize the risk of infection. Needles are never re-used, for instance, and clients are given careful instruction on how to care for their tattoo after it's done.

"The amount of problems is insignificant," Ciampi said, despite the growing number of people sporting tattoos.

That, in a nutshell, is also the CDC's position: It's possible that tattoos transmit disease -- and it does happen -- but hygienic procedures minimize the risk. There is so far little evidence -- except in "very selected populations" -- of the transmission of blood-borne diseases.

"Any procedure in which the skin is broken and in which the equipment could be contaminated with blood, has the potential to spread a variety of infections," said Miriam Alter, Ph.D., associate director for science in the Division of Viral Hepatitis at the CDC.