intake of 50 mg/day with the rounded estimate of dietary intake, 10 mg/day. Support for a LOAEL of 60 mg/day is provided by other studies showing altered copper balance after zinc supplementation (Fischer et al., 1984) (Table 12-7).

Uncertainty Assessment. An uncertainty factor (UF) of 1.5 was selected to account for interindividual variability in sensitivity and for extrapolation from a LOAEL to a NOAEL. Because reduced copper status is rare in humans, a higher UF was not justified.

Derivation of a UL. A LOAEL of 60 mg/day was divided by a UF of 1.5 to derive a UL of 40 mg/day for total intake of zinc from food, water, and supplements.

Data Selection. There is only one case report of zinc-induced copper deficiency anemia in a young child (Botash et al., 1992): a 13-month-old girl was given 16 mg/day of zinc for 6 months followed by 24 mg/day for 1 month. There are no reports on the adverse effects of zinc on copper status in children or adolescents. The UL values for infants are based on a study by Walravens and Hambidge (1976).

Identification of a NOAEL. Walravens and Hambidge (1976) fed 68 healthy, full-term infants either formula containing 1.8 mg/L of zinc (control) or the same formula supplemented with an additional 4 mg/L (total of 5.8 mg/L) of zinc for 6 months. No effects of zinc on serum copper or cholesterol concentrations or other adverse effects were found. Thus, 5.8 mg/L is the NOAEL selected. Multiplying the NOAEL for infants 0 through 6 months of age by the estimated average intake of human milk of 0.78 L/day (Allen et al., 1991; Butte et al., 1984; Heinig et al., 1993) results in a NOAEL of 4.5 mg/day.

Uncertainty Assessment. The length of the study by Walravens and