I don't know if I'd conclude it. What about the possibility of that the tattoo association is only at higher ages, because of some effect where younger people h

I don't know if I'd conclude it. What about the possibility of that the tattoo association is only at higher ages, because of some effect where younger people have a better immune system to ward off any immediate dangers of the tattoo ink and then it becomes inert. But getting it at 50, your body is less able to dispel the problematic compounds in the ink. Basically saying the ink's problems could just be front-loaded the first couple years. Without understanding those details (risk associated with when the tattoo was received and short-term vs. long term risk), I'd be wary about deciding 50 is safer than 20.