Barium sulfide is produced by carbothermic reduction of barium sulfate. Zinc sulfate is obtained from a variety of zinc products, often waste, by treatment with sulfuric acid.

Animal studies show exposure to titanium dioxide is linked to immunotoxicity, inflammation and neurotoxicity. 

Why does the exposure route matter, and what's the risk? 

Most notably, a European Food Safety Authority safety assessment published in May 2021 pointed to genotoxicity concerns, as suggested by previous research. Genotoxicity is the ability of chemicals to damage genetic information such as DNA, which may lead to cancer.