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Objectives-To assess the exposure to tungsten, cobalt, and nickel in a plant producing hard metals. The main components of hard metals are tungsten carbide and cobalt metal. According to recent studies, these two components may be responsible for both fibrogenic and carcinogenic eVects. Methods-87 workers were investigated (86 male, one female) with a median age of 42 (range 22-58) and a mean duration of exposure of 13 years (range 1-27 years). Stationary and personal air sampling, and biological monitoring were carried out. Hard metals are widely used in diVerent industries, mainly because of their resistance to corrosion, temperature, and wear. The most important use is as a component of alloys (cemented carbides). These materials were developed decades ago with the sintering process. The main components are tungsten carbide (about 90%) and cobalt metal (about 10%). Also, small amounts of nickel may be added. Results-Ambient1 After occupational exposure to hard metal dust adverse eVects on the upper and lower respiratory tract and on the skin have been reported. Although hard metal asthma and eVects on the skin are considered to be immunologically mediated reactions, the pathogenic model for interstitial lung disease (hard metal dust fibrosis) is still unclear.2 Several studies in the hard metal producing and processing industry suggested that cobalt is the main aetiological agent for the development of interstitial fibrosis. As a consequence of these studies preventive measures were initiated to reduce exposure to cobalt.3-5 These measures were very successful, especially the use of a metal working fluid containing a complex binder which generated a cobalt complex that reduced the bioavailability of cobalt. According to the results of biological monitoring, this measure has led especially in hard metal grinders to a significant reduction in exposure to cobalt. 6Several in vitro and animal experiments carried out over the past few years suggest that tungsten carbide also plays an important part in the pathogenesis of hard metal dust fibrosis as a result of a synergistic eVect. In vitro experiments have shown that the toxicity of hard metal dusts is determined by the physicochemical interaction of cobalt and tungsten carbide. Animal experiments have shown that the incidence of fibrotic lung changes is higher when a mixture of cobalt and tungsten carbide is administered, whereas cobalt and tungsten carbide alone lead to only low fibrogenic activity. In the United States and in some European countries the ambient threshold limit values are in the range of 1 mg/m 3 for soluble tungsten compounds and 5 mg/m 3 for insoluble ones. The aim of these limits is to prevent eVects on the central nervous system occurring after exposure to soluble compounds and irritative eVects on the respiratory tract with insoluble compounds. In Germany a maximum concentration at the workplace (MAK) value of 1 mg/m 3 for soluble tungsten compounds and 5 mg/m 3 for insoluble compounds has been set. 9 To date there are no biological...

Compared to studies in the literature this study is characterized by relatively high and non-confounded Al exposure of the welders, a repeated-measurement design, and multivariate analyses. However, the long-term stable interindividual differences of internal Al exposure were not related to interindividual differences in neurobehavioural performances. Additionally, the lack of processual changes of neurobehavioural performances during the observation phase and the insignificant group differences do not make it very probable that degenerative processes caused by Al had happened before study onset or stopped just at this time point.

In the production of lead batteries two antimony compounds occur: in the casting of grids antimony trioxide (Sb2O3), and in the formation of lead plates stibine (SbH3). Seven workers from the grid-casting area and 14 workers from the formation area were examined with regard to the antimony concentration in blood (Sb-B) and urine (Sb-U). Antimony air concentrations (Sb-A) were measured by means of personal air samplers. Urine samples were collected at the end of the working week, at the beginning (U1) and the end (U2) of the shift, and at the beginning of work following a weekend without Sb exposure (U3). At U2 among the casters, the median Sb-A exposure was 4.5 (1.18-6.6) micrograms Sb/m3 and among the formation workers, 12.4 (0.6-41.5) micrograms Sb/m3. The exposure in both groups is more than 10 times lower than the present threshold limit values. The median Sb-B concentrations in the preshift samples was 2.6 (0.5-3.4) micrograms Sb/l for the casters and 10.1 (0.5-17.9) micrograms Sb/l for the formation workers. The average Sb-U values (U2) were 3.9 (2.8-5.6) micrograms Sb/g creatinine in the casting area and 15.2 (3.5-23.4) micrograms Sb/g creatinine in the forming area. Our investigation indicates that the two antimony compounds show virtually equal pulmonary absorption and renal elimination. The statistically significant correlations between Sb-A/Sb-B and Sb-A/Sb-U form the basis for proposals regarding appropriate biological exposure limits for occupational antimony exposure.

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