Airborne concentrations of toxic metals resulting from the use of low melting point lead alloys to construct radiotherapy shielding.

Determinations of airborne concentrations of lead, cadmium, bismuth, and tin were made above vessels containing a "fusible" lead alloy (158 degrees F melting point) commonly used for construction of radiotherapy blocks. Fume concentrations were determined by collection on a membrane filter and analysis by atomic absorption spectrophotometry. Samples were obtained for alloy temperatures of 200 degrees, 400 degrees, and 600 degrees F. In all instances, concentrations were much lower than the applicable occupational limits for continuous exposure. The results of this study indicate that the use of a vented hood as a means of reducing air concentrations of toxic metals above and near vessels containing low temperature melting point lead allows commonly used in construction of radiotherapy shields appears unjustifiable. However, proper handling procedures should be observed to avoid entry into the body via alternate pathways (e.g., ingestion or skin absorption). Transmission data of a non-cadmium containing lead alloy with a melting point of 203 degrees F was ascertained and is reported on.