Derivation of a UL. The NOAEL of 0.9 mg/kg/day was divided by the overall UF of 30 to obtain a UL of 30 μg/kg/day for humans. The value of 30 μg/kg/day was multiplied by the average of the reference body weights for adult women, 61 kg, from Chapter 1 (Table 1-1). The resulting UL for adults is rounded to 2 mg/day (2,000 μg/day).

Although adult men and women have different reference body weights, the uncertainties in the estimation of the UL were considerable and distinction of separate ULs for men and women was therefore not attempted. This level is supported by limited human data from Deosthale and Gopalan (1974) who demonstrated no effect on uric acid or copper excretion in humans exposed to 22 μg/kg/day or 1.5 mg/day for an adult. Only four subjects were included in that study and no LOAEL was established. In addition, Turnlund and Keyes (2000) demonstrated no effect of 1.5 mg/day on copper metabolism in humans.

Infants. For infants, the UL was judged not determinable because of insufficient data on adverse effects in this age group and concern about the infant’s ability to handle excess amounts. To prevent high levels of intake, the only source of intake for infants should be from food and formula.

Children and Adolescents. There are no reports of molybdenum toxicity in children and adolescents. Given the dearth of information, the UL values for children and adolescents are extrapolated from those established for adults. Thus, the adult UL of 2 mg/day of molybdenum was adjusted for children and adolescents on the basis of relative body weight as described in Chapter 2 with use of refer-