Urinary excretion of o-cresol and hippuric acid after toluene exposure in rotogravure printing.
In 62 male rotogravure printers, the time-weighted average (TWA) toluene exposure during one workweek ranged from 8 to 496 mg/m3 (median 96). Post-shift urinary excretion of hippuric acid showed a poor correlation with the air toluene concentration. Level of o-cresol excretion ranged from 0.08 to 2.37 mmol/mol creatinine and was associated with the exposure (rS = 0.57, P less than 0.0001), although the variation was considerable. However, this metabolite was significantly influenced by smoking habits, both in the workers (0.34 vs 0.10 mmol/mol creatinine after adjustment to zero exposure for the smokers and non-smokers, respectively; P = 0.03) and in 21 unexposed controls (0.18 vs 0.06 mmol/mol creatinine; P = 0.002). The excretion of these metabolites was followed during vacation, when the workers were unexposed. The shared one-compartment half-time was 44 h (+/- SE 30, 82). After 2-4 weeks of vacation, the concentration of o-cresol was significantly higher for the smokers than the non-smokers (0.14 vs 0.06 mmol/mol creatinine; P = 0.02). No smoking-associated difference was found for the urinary hippuric acid concentration. However, there was an association between alcohol consumption and hippuric acid excretion (P = 0.03); no such difference was shown for o-cresol. These results demonstrate that hippuric acid excretion is unsuitable for biological monitoring of toluene exposure when the exposure level is below 200 mg/m3. Also, in spite of the favourable excretion kinetics, the impact of smoking and the large interindividual variation warrant the same conclusion for o-cresol as a means of monitoring low level exposure in an individual worker.
Nise
G
G
Department of Occupational Medicine, Karolinska Hospital, Stockholm, Sweden.
D000328:Adult; D003408:Cresols / Q000652:urine*; D006626:Hippurates / Q000652:urine; D006801:Humans; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D011327:Printing; D012044:Regression Analysis; D012907:Smoking / Q000009:adverse effects; D013997:Time Factors; D014050:Toluene / Q000009:adverse effects*
D003408:Cresols; D006626:Hippurates; D014050:Toluene; C030514:hippuric acid; C034047:2-cresol