Haemoglobin adducts as biomarkers of occupational exposure to 1,3-butadiene

Adducts of 1,2-epoxy-3-butene (EB) with haemoglobin were monitored in 17 workers from the 1,3-butadiene (BD) production unit of a petrochemical plant and in nine referents employed at the same factory but not exposed to BD. The air concentrations of BD were determined using stationary and personal monitoring. The ambient level of exposure of the plant workers handling butadiene containers (sampling and voiding) was on average 11.2 +/- 18.6 (mean +/- SD) mg/m3. Maintenance and laboratory workers were exposed to levels < or = 1.2 mg/m3. The particular haemoglobin adduct measured was 2-hydroxy-3-butenylvaline, formed by reaction of N-terminal valine with carbon 1 in EB. The adduct levels were increased (0.16 +/- 0.099 pmol/g; n = 10) in plant workers compared with the levels in maintenance and laboratory workers and controls (approximately 0.05 pmol/g; seven laboratory workers and nine controls evaluated). Thus, the method used for adduct determination--derivatization of 200-300 mg globin samples with penta-fluorophenyl isothiocyanate according to the N-alkyl Edman method and detection of the thiohydantoin derivatives by tandem mass spectrometry--is sufficiently sensitive to allow monitoring of exposure to BD down to the p.p.m. level.