Aniline dyes are derived from coal tar, a byproduct of burning coal — so yes, they have pretty toxic origins. Early dye workers suffered serious health effects, and some colors like Scheele’s Green (a related compound) were genuinely deadly. The dyes themselves can be skin and respiratory irritants, and aniline the base chemical is classified as a probable human carcinogen. The sweat stains on this are hard to look at because these toxins can be absorbed into the skin when chemicals in the dye a