A relatively non-toxic metal to humans and the second most abundant, the body has 2-3 grams of zinc. It can enter the body through inhalation, skin absorption, and ingestion, with the latter of the bunch being the most common. The mucosal cells of the digestive tract contain metallothionein proteins that store the zinc ions.
Nearly 90% of zinc is found in the bones, muscles, and vesicles in the brain. Zinc is a cofactor in hundreds of enzyme reactions and a major component of zinc finger proteins.