Studies in human lactation 3: molybdenum and nickel in human milk during the first month of lactation

Molybdenum and nickel were measured in 62 and 46 samples, respectively, of human milk collected from 13 women between delivery and 38 d postpartum. Trace elements were analyzed by graphite-furnace atomic absorption spectrophotometry, with standard additions to whole milk without pretreatment. Molybdenum levels (mean +/- SD) fell from 15.0 +/- 6.1 ng/mL on day 1 to an apparently constant level of 1-2 ng/mL by 1 mo. Nickel concentrations did not change with time; the overall mean was 1.2 +/- 0.4 ng/mL. Intakes of the elements by infants were calculated with test-weighing data on the fully breast-fed infants of these same mothers. By 1 mo, the average daily intake of molybdenum was 1.5 micrograms; that of nickel was 0.8 microgram.