Measurement of lung-retained contaminants in vivo among workers exposed to metal aerosols.

In Finland the amount of lung-retained contaminants has been measured among welders, foundry workers, and iron and steel factory workers. About 300 subjects have so far been measured since 1976. The method of measuring is based on the magnetic properties of metal aerosols. At the very beginning the method resembled the one suggested by D. Cohen. The original method was too slow, and data processing was not suitable for clinical or hygienic work. Therefore, the automatic and computerized instrument for measuring lung-retained contaminants was developed in cooperation with Outokumpu Oy. The resolution of the magnetic measurement is better than 0.05 nT corresponding to a sensitivity of 0.5 mg of magnetic contaminants in the lung in the form of magnetite. These figures mean that, in practice, a shipyard welder has enough contamination for measurement after one month's exposure. In addition, the present paper reviews the magnetic properties of metal aerosols briefly and summarizes the results of measuring different occupational groups.