Copper, zinc, cadmium, and lead in human blood from 19 locations in the United States.

Copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) were determined in 243 blood samples of male residents of 19 cities in the continental United States. The mean Cu and Zn concentrations of all samples agreed closely with values reported by other investigators. The means among the 19 locations, however, differed by threefold in Cu and fivefold in Zn. The levels of Cu and Zn in blood in 17 locations were normally distributed about their means except in two locations. Unlike Cu and Zn, the concentrations of Cd and Pb varied widely among samples from a given location.