Biological monitoring of workers exposed to styrene and acetone

Twenty-two workers exposed to styrene and acetone in two fiberglass industries were monitored on Monday and Thursday for 8 hours using passive dosimeters. Urine samples were collected at the end of the workshift and before the start of the work on the next morning (Tuesday and Friday). The charcoal disks of the passive dosimeters were analysed by gas-chromatography. Mandelic acid (MA) and phenylglyoxylic acid (PGA) were measured using a HPLC method; values were expressed in mg/g of creatinine. The 8-h TWA exposure values for styrene and acetone ranged respectively from 22 to 522 mg/m3 and 40-1581 mg/m3 on Monday; 25-423 mg/m3 and 55-579 mg/m3 on Thursday. Styrene TWA exposure values significantly correlate with the sum of metabolites at the end of workday (r = 0.70 on Monday and r = 0.95 on Thursday) and also at the next morning (r = 0.86 on Tuesday and r = 0.85 on Friday). A styrene exposure level of 213 mg/m3 (ACGIH-TLV) was associated with an excretion of metabolites (MA+PGA) higher on Thursday (803 mg/g creat) than on Monday (570 mg/g creat). The same result was found on Friday (459 mg/g creat) compared with Tuesday (305 mg/g creat). Moreover our data show that the simultaneous exposure to acetone does not modify the excretion of MA. In conclusion the TLV of styrene is associated with different values of metabolites at the beginning and at the end of the work-week.