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The following HTML text is provided to enhance online readability. Many aspects of typography translate only awkwardly to HTML. Please use the page image as the authoritative form to ensure accuracy. Zn2+/kg-d (duration unspecified). Administration of zinc acetate to rats (191 mg Zn2+/kg-d in feed for 3 mo) increased zinc levels in the heart, spleen, kidneys, liver, bone, and blood (Llobet et al. 1988). Mice fed 76.9 mg Zn2+/kg-d as zinc sulfate for 1 mo had increased levels of Zn2+ in the kidneys and liver (Schiffer et al. 1991). Newborn, young, and adult mice given a single oral dose of 4.6 mg zinc/kg as zinc chloride generally had the highest level of zinc in the liver, kidneys, lungs, bone, muscle, and carcass 1 d after dosing (He et al. 1991, as cited in ATSDR 1994). Once in the body, zinc induces and binds to metallothionein (a metal binding protein) (Goyer 1996). Retention of zinc bound to metallothionein in tissues provides a source of zinc for essential cell functions even when zinc intake is deficient. In humans and rats, zinc and metallothionein are distributed throughout the body, with a linear relationship between zinc and metallothionein concentrations in the liver (Heilmaier et al. 1987). Boric AcidIn humans, boron has been measured in the brain and liver following boric acid poisonings (see review, Moseman 1994). No other data were found on the distribution of boron in humans following exposure to boric acid or borax. In Fischer rats fed 9,000 ppm boron as boric acid (93–96 mg boric acid/kg-d) in the diet, boron was distributed throughout the soft tissues. Accumulation occurred in the bone, but not in the testis or the brain (Ku et al. 1991). Regardless of the compound or route of exposure, once in vivo, boron can form weak complexes with hydroxyl, amino, or thiol groups (Moore 1997). No data were found demonstrating that boron interacts with metallothionein. ExcretionZinc BorateNo data were identified that investigated the excretion of zinc borate in humans or animals following any route of exposure. Zinc OxideNo studies were identified that investigated the excretion of zinc in humans or animals following dermal application of any zinc compounds. Elevated levels of zinc were found in the urine of workers exposed to zinc
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