I think there is no doubt that tattoo ink contains some kind of toxins (including heavy metals and maybe others) which your body will be exposed to. But I suppose there's toxins from everyday life, even in whole foods, we can't completely avoid toxins in today's society, only try to limit them. Dental fillings and vaccinations seem to be the most mentioned way of getting heavy metals in your body, rather than tattoos, maybe that's because of the amount in them, or just that we aren't sure what or how much is in the ink.
Saying that, I assume many people still recovery from PFS and other conditions even with dental fillings, vaccines, and many other forms of toxins, so maybe it's no big deal.