Abstract
Epidemiological studies on metal levels in blood were carried out. Evidence suggested the existence of a different trend in serum-iron levels in relation to blood lead levels in nonoccupationally exposed males (negative trend) and females (positive trend). There was a positive relation between blood lead levels and blood manganese levels in children and occupationally exposed male workers. Blood metal levels increased with age in young children. There was evidence for an influence of socioeconomic class on blood lead levels in children. A direct and an indirect effect of smoking was found on blood lead levels and on the activity of delta-aminolevulinic acid dehydratase activity in erythrocytes in adult nonoccupationally exposed females.