I know that Hep B, Hep C and HIV are more common in the prison population than in most non-prison populations. I'd say that getting a tattoo from a dubious practitioner would be pretty risky. It obviously isn't the only cause of the high rates in the prison, but I'm sure that if tattoos are done with used equipment then there is some disease transmission. Tattoos are certainly a major source for Hep C transmission.
Of course, as already noted, if the goal is to prevent gang tattoos and similar stuff then the program won't do much.