Geographic distribution of selenium in human milk.

Data were collected on the selenium concentration in human mature milk from a total of 241 subjects who resided in or near cities located in 17 states across the United State. The overall mean value for the selenium content of mature human milk was 0.018 ppm Se. Most of the individual values for selenium in human milk fell within the narrow range of 0.007 to 0.033 ppm Se, yet there was evidence for geographic variations in the selenium content of milk collected from the various cities.