The distribution of zinc to tissues has not been measured in humans following ingestion. However, there are a number of studies in rodents that have investigated the distribution of zinc following oral exposure to zinc compounds. Weigand and Kirchgessner (1992) (as cited in ATSDR 1994) determined that rats fed mg Zn 2+ /kg-d for an unspecified amount of time, had greater amounts of zinc distributed primarily to the kidneys and pancreas than to the liver. Administration of zinc acetate to rats (191 mg Zn 2+ /kg-d in food for 3 mo) increased zinc levels in the heart, spleen, kidneys, liver, bone, and blood (Llobet et al. 1988). Mice fed either mg Zn 2+ /kg-d as zinc sulfate (Schiffer et al. 1991, as cited in ATSDR 1994) or 38 mg Zn 2+ /kg-d as zinc nitrate (Cooke et al. 1990, as cited in ATSDR 1994) for 1 mo had increased levels of Zn 2+ in the kidneys and liver. Newborn, young, or adult mice that received a single oral dose of mg Zn 2+ /kg as zinc chloride generally had the highest level of zinc in the liver, kidneys, lungs, bone, and muscle 1 d after dosing (He et al. 1991, as cited in ATSDR 1994).