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Isocyanate exposure assessments using the MAP method: a summary of recent NIOSH Health Hazard Evaluations.

Reh-C; Streicher-R; Roegner-K
American Industrial Hygiene Conference and Exposition, June 2-7, 2001, New Orleans, Louisiana. Fairfax, VA: American Industrial Hygiene Association, 2001 Jun; :75
Background: NIOSH recently developed a sampling and analytical method for determining airborne exposures to isocyanate-containing compounds. The method's derivatizing agent is 1-(9-anthracenylmethyl) piperazine (MAP), which converts the isocyanate into a stable urea derivative. When sampling for isocyanates, air is drawn through a MAP impregnated filter, MAP-containing impinger, or impinger-filter combination, depending on the process and/or isocyanate species. The samples are analyzed by pH-gradient high pressure liquid chromatography with ultraviolet and fluorescence detection. Methods: The MAP method was recently used to evaluate airborne isocyanate exposures from four industrial operations. Three of these operations were spray painting, three were foam packaging, one was foam injection, and one was foam molding. The following isocyanates were used during these operations: hexamethylene diisocyanate (HDI), toluene diisocyanate (TDl), diphenylmethane diisocyanate (MDl), HDI-based polyisocyanates, MDl based polyisocyanates, and TDI prepolymer. Results: The range of exposures by operation and isocyanate species are shown below: Spray Painting: HDI - none detected (ND) to 1.9 micrograms per cubic meter (ug/m3), HDI polyisocyanate - ND to 164 ug/m3, MDl - 300 to 1364 ug/m3, MDI polyisocyanate - 304 to 1080 ug/m3, TDI - 5.1 to 9.6 ug/m3, and TDI prepolymer - 10.4 to 28.9 ug/m3. Foam Packaging: MDI - ND to 7.5 ug/m3, and MDI polyisocyanate - ND to 13.4 ug/m3. Foam Injection: MDI - ND to 5 ug/m3, and MDl polyisocyanate - ND to 38 ug/m3. Foam Molding: TDI - ND to 8.1 ug/m3. These facilities used various exposure and process emission controls to protect workers from potentially hazardous isocyanate exposures. An analysis of these control methods provides information on effective methods for controlling isocyanate exposures. Conclusion: The data from these evaluations demonstrate some of the advantages associated with the MAP method. This method is capable of measuring the different monomer and/or oligomer species used in a given process or formulation, and the improved sensitivity is especially useful when measuring short-term or task-based exposures.
Sampling; Analytical-methods; Air-contamination; Air-sampling-techniques; Isocyanates; Liquid-chromatography; Exposure-levels; Spray-painting; Statistical-analysis; Emission-sources; Hazards; Monomers
822-06-0; 584-84-9; 101-68-8
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American Industrial Hygiene Conference and Exposition, June 2-7, 2001, New Orleans, Louisiana