Overview on Isocyanate-induced Health Disorders
نویسندگان
چکیده
The determination of isocyanates concentrations in air is complicated by thepresence of these substances as monomers and oligomers as well as in thevapor and aerosol phases. Direct-reading instruments (DRIs) are available fordetermining the diisocyanate concentrations in workplace air, but they arecalibrated for the monomers only. Industry uses polymeric diisocyanateswhich contain monomers and oligomers. This study evaluated DRIs underlaboratory conditions for their use in determining the total concentration ofisocyanates monomers and oligomers that are contained in commercialpolymeric diphenylmethane diisocyanate (PMDI). Aerosols of differentcommercially available PMDIs were generated at known concentrations in anexposure chamber. Parallel sampling was carried out using two laboratorymethods and direct-reading instruments (DRIs) for evaluation purposes.Response curves for five commercial PMDIs were produced at chamberconcentrations ranging from 4 to 40 ppb (0.05 at 0.46mg/m) for the differentinstruments studied. For a given aerosol particle size distribution (MMAD3μm), the different PMDIs slightly affect the instruments’ responses. Finally,relative humidity (RH) above 60% was shown to have an effect on theresponses of most of the instruments studied. These results confirm that DRIscan be used for PMDI determinations with appropriate calibration (usingaccepted method); however, the user needs to know the limitations of theseinstruments.
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