Lead exposure during demolition of a steel structure coated with lead-based paints. I. Environmental and biological monitoring.

Demolition of a steel railway bridge was carried out by nine workers using flame-torch cutting. The air in the breathing zone of the workers contained from 2 to 38 mg of lead/m3, which is a very high level in comparison with the Dutch exposure limit of 0.15 mg/m3 (8-h time-weighted average). Without very effective respiratory protection these concentrations may result in acute lead poisoning. Upwind of the flame-torch exposure the level was below the exposure limit, whereas downwind lead concentrations of up to ten times the exposure limit were observed. Although filtering facepieces were used by the workers, average blood lead concentrations of about 4.5 mumol/l were rapidly attained. Possibly under these work conditions this value represents a maximum concentration attainable in blood. After termination of the exposure, there was a fast decrease of lead in the blood. This finding indicates that lead was mainly present in rapidly exchangeable compartments like blood. No stable correlation between the concentration of lead in blood and the concentration of zinc protoporphyrin in blood was found.