Identification of a NOAEL. The data of Shearer and Hadjimarkos (1975) showed that a human milk selenium concentration of 60 µg (0.8 µmol)/L was not associated with known adverse effects. Thus, 60 µg (0.8 µmol)/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 results in a NOAEL of 47 µg (0.6 µmol) or approximately 7 µg (90 nmol)/kg/day. This is in agreement with another study by Brätter et al. (1991).

Brätter et al. (1991) studied effects of selenium intake on children in two seleniferous areas of the foothills of the Venezuelan Andes, using Caracas as a control. Mean human milk selenium content was 46 µg (0.6 µmol)/L in Caracas compared to 60 and 90 µg (0.8 and 1.1 µmol)/L in the two seleniferous areas. Mean selenium concentrations in infant blood in the area with the highest adult selenium intake were reported to be intermediate between those seen in the seleniferous and the nonseleniferous regions.

Uncertainty Assessment. There is no evidence that maternal intake associated with a human milk level of 60 µg (0.8 µmol)/L results in infant or maternal toxicity (Shearer and Hadjimarkos, 1975). Therefore, a UF of 1 is specified.

Derivation of a UL. The NOAEL of 47 µg (0.6 µmol)/day was divided by a UF of 1, resulting in a UL of 47 µg (0.6 µmol) or approximately 7 µg (90 nmol)/kg/day for 2 through 6-month-old infants. Thus, the infant UL and the adult UL are similar on a body weight basis. Also, there is no evidence indicating increased sensitivity to selenium toxicity for any age group. Thus, the UL of 7 µg/kg body weight/day was adjusted for older infants, children, and adolescents on the basis of relative body weight as described in Chapter 4 using reference weights from Chapter 1 (Table 1-1). Values have been rounded down to the nearest 5 µg.

Selenium UL Summary, Ages 0 Months through 18 Years

UL for Infants

 

0–6 months

45 µg (0.57 µmol)/day of selenium

7–12 months

60 µg (0.76 µmol)/day of selenium

UL for Children

 

1–3 years

90 µg (1.1 µmol)/day of selenium

4–8 years

150 µg (1.9 µmol)/day of selenium

9–13 years

280 µg (3.6 µmol)/day of selenium

UL for Adolescents

 

14–18 years

400 µg (5.1 µmol)/day of selenium



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