[Interference of acetone in styrene metabolism in subjects exposed to both solvents]

Thirty-seven workers exposed to styrene and acetone in fiberglass industry were monitored on Monday and Thursday for 8 hours (two subsequent samplings of 4 hours each) using passive dosimeters (mod. TK200). The charcoal disks of the passive dosimeters were analysed by gas-chromatography. Urine samples were collected at the end of the workshift and before the start of the workshift the next morning (Tuesday and Friday). Mandelic acid (MA) and phenylglyoxylic acid (PGA) were measured in the urine, using a HPLC method; values were expressed in mg/g of creatinine. The 8-h TWA exposure values ranged from 10 to 522 and 13 to 1581 mg/m3 on Monday and 8 to 423 and 10 to 579 mg/m3 on Thursday for styrene and acetone, respectively. Styrene TWA exposure values significantly correlated with the sum of metabolites at the end of workday (r = 0.72 on Monday and r = 0.91 on Thursday) and also the next morning (r = 0.88 on Tuesday and r = 0.85 on Friday). A calculated styrene exposure level of 213 mg/m3 (ACGIH-TLV) was associated with an excretion of metabolites (MA+PGA) higher on Thursday (814 mg/g creat.) than on Monday (600 mg/g creat.). The same observation was made on Friday (409 mg/g creat.) as compared with Tuesday (302 mg/g creat.). In conclusion, the TLV of styrene was associated with different values of metabolites at the beginning and at the end of the work-week. Moreover our data show that the simultaneous exposure to acetone does not modify the excretion of MA.