Zinc, copper and environmental factors in the aboriginal peoples of the North West.

Three-hundred Aboriginal people five to 70 yr have been studied at three missions in the north west of Australia-Beagle Bay, Lombadina and One Arm Point. The prevalence of hypozincaemia and hypercupraemia (a departure of more than 2 S.D. from the expected normal) has been assessed. Plasma iron concentration was determined. Half of the individuals had hypozincaemia and for some age groups the prevalence was greater (almost 100% for 15 to 20-year-old females at Lombadina). Hypercupraemia was prevalent and ranged from 70 to 100% for most age groups. Hypoferraemia was detected frequently. By the use of anthropometric methods the children were found to be growth retarded and to have reduced weight for height. These people are known to be infected with intestinal parasites which cause bleeding into the bowel or malabsorption which can cause losses of zinc or failure of adsorption. They prefer unleavened bread which contains phytic acid which inhibits zinc absorption. The soil is zinc deficient and the climate conducive to large losses of zinc in sweat. Geophagia is practiced and pica is found to occur in children. Preliminary evidence of elevated copper status is available. We speculate that growth failure may be related to zinc deficiency or copper toxicity.