Multi-element follow up in biological specimens of hard metal pneumoconiosis

The movement of Co and the other components of the hard metal in the body fluids, their solubility, their links to the cells and proteins of the body, and their clearance are largely unknown. The first aim of this work is to evaluate whether Neutron Activation Analysis (NAA), a new analytical technique based on the radiochemical separation of samples irradiated in a Nuclear Reactor, may be suitable for studying the movement of elements in tissues or body fluids of workers over time. We have investigated seven hard metal workers, all employed in the grinding process, with NAA studies (single study in two, follow-up in five) of 29 elements on lung tissue, BAL fluid, blood, urine, pubic hair, toenails and sperm. In three, the diagnosis of hard metal pneumoconiosis was easy; in the other four, due to evident bilateral hilar lymphadenopathy, it was difficult to distinguish between pneumoconiosis and sarcoidosis stage II, and the final diagnosis, after pulmonary biopsy, was hard metal pneumoconiosis in three, and sarcoidosis in one. In spite of high potential, NAA gives a number of unexpected results, with apparent controversies and no clear relationship in the evolution of levels of Co, W and Ta: there is no simple explanation for such apparent inconsistencies at present, so that the study of the movement of elements in body fluid sometimes appears disappointing with this technique. Other observations were noted from the data available: 1) the concentration of elements (Co, Ta, W) in lung tissue is far higher than in BAL fluid, but the factor is so variable that BAL fluid cannot be taken as representative of the concentration of elements in lung tissue. 2) High concentrations in tissues or body fluids are indicative for exposure, but not for disease. In the light of available data, there are no levels above which development of disease is inevitable. 3) When the problem is to distinguish between sarcoidosis and pneumoconiosis in exposed subjects, the concentration of elements is of no value, and the pulmonary biopsy is still necessary. However a NAA study may be helpful to confirm the presence of the offending agent, and to avoid pulmonary biopsy in cases where the occupational history is unclear.