[Proceedings: Lung lesions caused by "rare earths"].

Three reproduction photographers were found to have light patchy and reticular infiltrates on the chest x-rays. They had a 30-year history of inhaling "rare earths" and thorium deriving from the dust of the electric carbon arc-light. The diagnosis was confirmed by whole-body gamma-counting in all cases and by additional lung biopsy in one. This type of pneumoconiosis shows no definite disease progression and no serious functional deterioration.