Clearance of radioactive tantalum from the human lung after accidental inhalation.

Techniques of body radioactivity measurement were used to study the clearance of activated tantalum oxide accidentally inhaled by three reactor workers. The whole-body retention after 7 days was about 1% of the initial deposit. In one subject studied for a further 424 days the residual activity in the thorax was cleared with a biological half-life of about 1,400 days. The results support indications from other studies that tantalum powder administered in aerosol bronchography may be subject to prolonged alveolar retention.