Trace element concentrations in blood and hair of young apprentices of a technical-professional school

The concentrations of total Fe, Cu, Mn, Zn, Pb, Cr, Ni and Ca in the whole blood of young male apprentices of a technical-professional school, who are exposed to low doses of fumes from manual metal arc welding of mild steel, were monitored over their 2 years of apprenticeship in order to evaluate the influence of occupational exposure on biological metal levels. The results were compared with those from a control group of the same sex and age and living in the same geographic area. For comparison, monitoring of the same metal levels in the hair of both groups of individuals were also carried out. In the apprentices, the mean metal concentrations in blood at the end of the study were statistically significantly higher for Cu, lower for Fe and Mn and similar for the remaining metals. The levels of Fe significantly decreased whereas the levels of Cu were significantly increased during the study. A systematic influence of the exposure period on the levels of Mn was not observed. All the metal concentrations measured in the blood and hair of both apprentices and controls fell in the very large range of published reference levels. Seasonal variation (higher levels in the summer) of the hair metal concentrations were observed for Mn, Cu, Pb, Ni, Zn and Ca.