Exposure assessment in the hard metal manufacturing industry with special regard to tungsten and its compounds.
OBJECTIVE
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 effects.


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.


RESULTS
Ambient monitoring yielded maximum tungsten concentrations of 417 microg/m3 in the production of heavy alloys. A maximum cobalt concentration of 343 microg/m3 and a maximum nickel concentration of 30 microg/m3 were found at the sintering workshop. The highest urinary cobalt concentrations were found in the powder processing department. The mean concentration was 28.5 microg/g creatinine and the maximum value was 228 microg/g creatinine. The maximum nickel concentration in urine of 6.3 microg/g creatinine was detected in the department producing heavy alloys. The highest tungsten concentrations excreted in urine were found in grinders and had a mean value of 94.4 microg/g creatinine and a maximum of 169 microg/g creatinine. Due to the different solubility and bioavailability of the substance, there was no correlation between the tungsten concentrations in air and urine on a group basis.


CONCLUSIONS
Despite its low solubility, tungsten carbide is bioavailable. The different bioavailability of tungsten metal and tungsten compounds has to be considered in the interpretation of ambient and biological monitoring data in the hard metal producing industry. The bioavailability increases in the order: tungsten metal, tungsten carbide, tungstenate. Only if both monitoring strategies are considered in combination can a valid and effective definition of high risk groups be derived.
Kraus
T
T
Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine of the University of Erlangen-Nürnberg, Schillerstrabetae 25 and 29, D-91054 Erlangen, Germany. thomas.p.kraus@rzmail.uni-erlangen.de
Schramel
P
P
Schaller
K H
KH
Zöbelein
P
P
Weber
A
A
Angerer
J
J
D000328:Adult; D000395:Air Pollutants, Occupational; D001682:Biological Availability; D003035:Cobalt / Q000493:pharmacokinetics / Q000652:urine; D004784:Environmental Monitoring / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008452:Maximum Allowable Concentration; D008669:Metallurgy; D008875:Middle Aged; D009532:Nickel / Q000493:pharmacokinetics / Q000652:urine; D016273:Occupational Exposure / Q000009:adverse effects*; D012995:Solubility; D017973:Tungsten Compounds / Q000493:pharmacokinetics* / Q000652:urine
D000395:Air Pollutants, Occupational; D017973:Tungsten Compounds; D003035:Cobalt; D009532:Nickel