Use of a whole blood competitive immunoassay for the assessment of worker exposures to propylene oxide at three manufacturing facilities.
The level of N-(2-hydroxypropyl)valine adducts in haemoglobin has been shown to correlate well with workplace exposure to propylene oxide (PO). However, the analytical method, using the modified Edman degradation procedure, is prohibitively time-consuming and expensive for use as a routine workplace exposure measurement tool. As an alternative, AB Biomonitoring Ltd of Cardiff, Wales, developed a competitive immunoassay for the determination of N-(2-hydroxypropyl)valine adducts in human haemoglobin. Studies showed that whole blood samples analysed using an enzyme linked immunosorbent assay (ELISA) and the modified Edman degradation procedure over the concentration range 3.7-992 nmol N-(2-hydroxypropyl)valine g(-1) haemoglobin are in good agreement (correlation coefficient 0.998, n = 10). The intervariance and intravariance data indicate the repeatability of the ELISA method over the assay conditions employed and show that it is robust over its working range [2-200 pmol N-(2-hydroxypropyl)valine g(-1) haemoglobin]. The assay employs a whole blood matrix and has a working range of 2-6000 pmol g(-1) Hb (equivalent to up to 5 ppm PO exposure, 8 h per day, 5 days per week, over 4 months). The practicality of the assay was tested by assessing exposures to PO at three world-scale manufacturing sites in France and The Netherlands. Over 800 samples were taken over a 2 year period from operators, maintenance fitters and office staff. The data, typically <50 pmol g(-1) globin, indicate that exposures were significantly <0.1 ppm at all times (The Dutch occupational exposure limit is 2.5 ppm over 8 h). Samples were taken after a major turnaround and also before and after the start-up of a newly commissioned plant. All data indicated that high levels of control were effective in minimizing exposure. This study has shown that the immunoassay is a powerful tool for the exposure component of future epidemiology studies, as well as a definitive demonstration of the effectiveness of exposure controls.
Jones
Alan L
AL
Lyondell Chemical Europe, Inc., Lyondell House, Bridge Avenue, Maidenhead, Berkshire SL6 1YP, UK. alan.jones@lyondell.com
Van der Woord
Miriam
M
Bourrillon
François
F
D004784:Environmental Monitoring / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D004852:Epoxy Compounds / Q000097:blood*; D006454:Hemoglobins / Q000737:chemistry*; D006801:Humans; D016273:Occupational Exposure / Q000032:analysis*; D015203:Reproducibility of Results; D014633:Valine / Q000031:analogs & derivatives* / Q000097:blood
D004852:Epoxy Compounds; D006454:Hemoglobins; C057443:2-hydroxypropylvaline; D014633:Valine; C009068:propylene oxide