Lead in human scalp hair: some factors affecting its variability.

The accumulation of lead in human scalp hair was compared in male and female children and adults from various locations in the United Sates, Japan, Yugoslavia, Iran, and South Africa. The most significant variables which influenced the concentration of lead in hair were ingestion of lead-containing substances, exposure to lead of environmental origin, place of residence, site from which the hair specimen was sampled relative to its distance from the scalp, and age. The least significant variables were sex and nutritional deficiencies.