Metal determinations in biological specimens of diseased and non-diseased hard metal workers

Abstract

Biological monitoring of Co, Ta and W, using mainly neutron activation analysis, was carried out on the urine, blood, pubic hair and toe nails of 251 subjects occupationally exposed to hard metal dusts (23 individuals were diagnosed as ‘diseased subjects’, affected by asthma and/or lung fibrosis). Airborne dust at hard metal workplaces were also analyzed for Co and W content. Cobalt and tungsten exposure at workplaces varied widely and frequently exceeded the TLV (0.05 mg Co/m 3). Cobalt in urine (CoU), which is better than Co in blood (CoB), could represent a valuable indicator in discriminating between exposed groups, but is of little value as an indicator of exposure for single individuals. The high concentrations of cobalt in pubic hair (CoH) and toe nails (CoN) could also be valuable indicators of exposure although they are not useful, however, in establishing quantitatively the levels of cobalt accumulation. Tungsten and tantalum in pubic hair (WH and TaH) and toe nails (WN and TaN) also seem to be useful indicators in proving hard metal exposure qualitatively. The determination of these two elements, rather than cobalt, in the bronchoalveolar lavage (BAL) is very useful in complementing the diagnosis of hard metal disease proving hard metal exposure. The analysis of the BAL subfractions showed that W and Ta were firmly incorporated into the macrophage fraction while Co was distributed between cellular fraction and supernatant, which suggests a different mobility of hard metals in pulmonary tissue. The metal concentrations determined when submitted to statistical analysis indicated a positive correlation with P < 0.001 for the pairs (CoBCoU), (CoW) in urine, and (CoW) in toe nails. Multielement analysis of biological specimens from diseased subjects suggests that hard metal disease does not relate to Co, W and Ta levels in the specimens considered. The disease does not depend on sex, age, working age and length of hard metal exposure. These findings support the theory on the possible haptenic properties of Co which may induce hypersensitivity and immuno-related toxic effects.