No, I believe cancer from hair dyes was caused by touching dye during application. Poisons are volatile, dye is only toxic, while it is drying.
Tattoo pigment particles are quite inert.
How do you know they are inert? The ingredients are mostly unstudied and unregulated.
If they weren't (mostly) inert, I guess they would do a poor job at staying in place, which is the whole point of tattoos.
> Tattoo pigment particles are quite inert.
Asbestos is quite inert, which is a good property for fire retardant materials to have. However it does have an unfortunate effect when inhaled.
Hair is dead, skin is not. Your body doesn't care about what you do to your hair, you can cut it, dye it, anything as long as it doesn't touch the root. Tattoos are about injecting a foreign substance in live tissue, which triggers an immune response, and that's what the article is about. There is a reason tattoos hurt and haircuts don't.
Well sure, but the scalp underneath the hair that's gotta have some skin properties - sure it's thicker than the rest of the skin and has some protective properties against some forms of environmental damage but the dye does go in there and years of use should cause _some_ thing - not sure there's any research around what exactly.
In dyeing your hair, do you inject the dye beneath the epidermis?
Skin absorbs stuff without having to inject it below.