Age- and sex-related differences in zinc and lead levels in human hair.

The hair of 1518 healthy subjects between newborn and 70 yr old living in Linfen city and the surrounding rural area in Shanxi province, North China, was analyzed by means of a flame atomic absorption spectrophotometer method in order to determine the concentrations of zinc (Zn) and lead (Pb). The collected samples were subdivided on the basis of age, sex, and place of residence (urban and rural). In female hair, the contents of Zn were higher than in male, but the hair Pb concentrations of males were slightly higher than those of females. Age seems to have a different influence on the two elements. The maximum amount of hair Zn was found generally in newborns. From the baby group (<1 yr) to the puberty group (15-19 yr), Zn levels in hair increased with age, and then Zn levels decreased with age from the puberty group to elderly group (61-70 yr). The hair Pb levels were the lowest in newborns, increased with age from newborn to infant (1-2 yr), and then decreased with age from infant to the elderly. It was shown that the hair Pb and Zn levels were inversely related in various age groups, suggesting that there is possibly antagonism between Pb and Zn in the human body. The results also showed the hair Pb levels of subjects living in the urban area, except for newborns, were higher than those of subjects residing in the rural area. However, no difference between the hair Zn contents of the populations residing in urban and rural areas.