CONCENTRATIONS OF URINARY METABOLITES IN WORKERS EXPOSED TO MONOCHLOROBENZENE AND VARIATION IN THE CONCENTRATION DURING A WORKSHIFT

Urinary concentrations of metabolites o monochlorobenzene were examine d in 10 male workers exposed to the compound while synthesising interm ediate products for dyes. Their individual exposure concentrations wer e monitored for the whole workshift and samples of urine were collecte d at the start and end of the workshift, during it, and during the noo n recess. The concentrations of four metabolites, 4-chlorocatechol and o-, m-, and p-chlorophenol, in the urine samples were measured. The i nvestigation was performed on Monday and Tuesday in one week and on Tu esday and Wednesday in another week. The concentrations of 4-chlorocat echol in urine collected during the last four hours and at the end of the workshift were proportional to the eight hour time weighted averag e exposure to monochlorobenzene. The concentration in urine collected during the noon recess showed a linear correlation with the four hour time weighted average in the morning. Similarly, linear relations were obtained for urinary p-chlorophenol. The ratio (as monochlorobenzene) of p-chlorophenol to 4-chlorocatechol concentrations at the start of the workshift was 0.39 and at the end of the workshift was 0.22. The r atios of the urinary concentrations 15 hours after exposure to those a t the end of exposure were 0.24 for 4-chlorocatechol and 0.44 for p-ch lorophenol. The p resent study also showed that variations in exposure at the workplace were reflected by changes in concentrations of urina ry metabolites during the workshift.