BIOLOGICAL MONITORING OF WORKERS EXPOSED TO LOW-LEVELS OF 2-BUTOXYETHANOL

Objectives: (1) To assess the value of urinary butoxyacetic acid (BAA) measurement for the monitoring of workers exposed to low concentratio n of 2-butoxyethanol (BE); (2) to evaluate the in vivo effect of low o ccupational BE exposure on the erythrocyte lineage; and (3) to test th e possible influence of genetic polymorphism for cytochrome P450 2E1 ( CYP 2E1) on urinary BAA excretion rate. Methods: Thirty-one male worke rs exposed to BE in a beverage package production plant were examined according to their external (BE) and internal (BAA) solvent exposure, The effect of this exposure on erythrocyte lineage [red blood cell num eration (RBC), hemoglobin (Hb), hematocrit (Htc), mean corpuscular vol ume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglo bin concentration (MCHC), haptoglobin (Hp), reticulocyte numeration (R et) and osmotic resistance (OR)]. hepatic [aspartate aminotransferase (GOT), alanine aminotransferase (GPT)] and renal [plasmatic creatinine , urinary retinol binding protein (RBP)] parameters was also investiga ted, DNA purified from whole blood was used for CYP 2E1 genotyping. Re sults: Average airborne concentration of BE was 2.91 mg/m(3) (0.59 ppm ) with a standard deviation of 1.30 mg/m(3) (0.27 ppm). There was a re latively good correlation between external and internal exposure estim ated by measuring BAA in post-shift urine samples (average 10.4 mg/g c reatinine; r = 0.55; P = 0.0012). Compared with a matched control grou p (n = 21) exposed workers had a statistically significant decrease (3 .3%; P = 0.03) in Hct while MCHC was increased (2.1%; P = 0.02). No si gnificant difference was observed either in other erythroid parameters or-in hepatic and renal biomarkers. One exposed individual exhibited a mutant allele with increased cytochrome P450 oxidative activity whic h coincided with a very low urinary BAA excretion. Conclusions: Single determination of BAA in post-shift urine samples can be used to asses s exposure to low levels of BE. A slight but significant effect on ery throid parameters suggesting membrane damage was observed in exposed w orkers. The influence of the genetic polymorphism for CYP 2E1 deserves further investigation for the interpretation of urinary BAA measureme nts.