Annals of Occupational Hygiene Advance Access originally published online on January 24, 2006
Annals of Occupational Hygiene 2006 50(4):385-393; doi:10.1093/annhyg/mei075
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© 2006 British Occupational Hygiene Society Published by Oxford University Press
Original Article |
Determination of Airborne Isocyanates Generated During the Thermal Degradation of Car Paint in Body Repair Shops
1 McGill University, 3450 University Street, FDA Building, Room 31, Montreal, Quebec, Canada H3A 2A7; 2 Institut de recherche Robert-Sauvé en santé et en sécurité du travail, 505 de Maisonneuve Blvd. West, Montreal, Quebec, Canada H3A 3C2
* Author to whom correspondence should be addressed. e-mail: Andre.Dufresne{at}mcgill.ca
Polyurethanes are widely used in car paint formulations. During thermal degradation, such polymeric systems can generate powerful asthmatic sensitizing agents named isocyanates. In body repair shops, the thermal degradation of car paint can occur during abrasive processes that generate enough heat to involve release of isocyanates in air. An environmental monitoring study was performed in two body repair training schools and in a body repair shop to evaluate the workers' exposure to isocyanates during cutting, grinding and orbital sanding operations. For sampling, cassettes containing two 1-(2-methoxyphenyl)piperazine (MOPIP)-coated glass fiber filters (MFs) (
5 mg of MOPIP per filter) and bubblers containing 15 ml of MOPIP solution in toluene (1.0 mg ml–1) backed at the outlet with cassettes containing two MFs were used. Tandem mass spectrometry was used to analyze the MOPIP derivatives of isocyanic acid (HNCO), all the linear aliphatic isocyanates ranging from methyl isocyanate (Me-i) to hexyl isocyanate, all the alkenyl isocyanates ranging from propylene isocyanate to hexylene isocyanate, 1,6-hexamethylene diisocyanate (HDI), trans- and cis-isophorone diisocyanate (IPDI), 2,4- and 2,6-toluene diisocyanate (TDI), 2,4'-; 2,2'- and 4,4'-methylenediphenyl diisocyanate (MDI), phenyl isocyanate (Ph-i) and p-toluene isocyanate (p-Tol-i). The instrumental detection limits (LOD) were in the 0.13–0.75 µg of NCO per m3 range for 15 l air samples converted into 3 ml liquid samples. The isocyanate concentrations detected in the workers' breathing zone were in the 1.07–9.80 µg of NCO per m3 range for cutting, 0.63–3.62 µg of NCO per m3 range for grinding and 0–1.29 µg of NCO per m3 range for sanding. However, a rapid decrease of the isocyanate concentration was observed while moving away from the emission source. Among the isocyanates detected the most abundant were the monomers (MDI, HDI, TDI and IPDI) and Me-i.
Keywords: body repair shop • car paint • cutting and orbital sanding • grinding • isocyanate • polyurethane • thermal degradation
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