Why might Domino's inks contain heavy metals?

Question:

Why might Domino's inks contain heavy metals?

Answer:

Black dyestuffs traditionally uses as the colourant in Continuous Ink Jet (CIJ) inks are often chromium (III)- based, and such dyes may contain trace levels of chromium (VI). As legislative and environmental demands increase, new ink formulations use alternative chrome-free dyestuffs, or substitute dyestuffs with pigments.