| HN Mirror

They're injecting an artificial material under the skin; it may not have immediate health effects, barring contamination/infection (which itself is a real risk that shouldn't be ignored), but the long-term effects are less well understood. So, in a sense, they're similar to cigarettes that way: they affect your body, but how much? The long-term effects of cigarettes are much better understood today, but that wasn't the case 60 years ago when cigarettes were all the rage. But since so many people smoked like chimneys back then, we can now look at them today and see what their health is like, and compare to others who didn't smoke. 60 years ago, no one except sailors had tattoos, so no one investigated them much and there's not that much long-term data available (not many old people with tattoos to see the health effects). But, like in the 1960s with cigarettes, tattoos are all the rage today (in America), so in 30-60 years we'll be seeing the health effects of this craze.

But the real point here is to respond to the OP's idea that tattoo ink should be regulated as a medical product. It's not a medical product, just like cigarettes aren't, piercings, aren't, etc. Medical products are things that are supposed to improve your health and affect your body, so of course there's no call to regulate cigarettes, alcohol, heroin, methamphetamine, or tattoo ink as medical products, because they simply aren't (they don't improve your health, nor claim to usually), even though they obviously can affect your health.