Significance and Use
5.3 Diisocyanates and polyisocyanates are irritants to skin, eyes, and mucous membranes. They are recognized to cause respiratory allergic sensitization, asthmatic bronchitis, and acute respiratory intoxication (6-9).
5.4 The American Conference of Governmental Industrial Hygienists (ACGIH) has adopted a Threshold Limit Value–Time Weighted Average (TLV—TWA) of 0.036 mg/m3 with a Short-Term Exposure Limit (STEL) of 0.14 mg/m3 for 2,4-TDI (10). The Occupational Safety and Health Administration of the U.S. Department of Labor (OSHA) has a permissible exposure limit of 0.02 ppm(V) or 0.14 mg/m3 of TDI as a ceiling limit and 0.005 ppm (V) or 0.036 mg/m3 as a time-weighted average (11).
5.5 Monitoring of respiratory and other problems related to diisocyanates and polyisocyanates is aided through the utilization of this test method, due to its sensitivity and low volume requirements (15 L). Its short sampling times are compatible with the duration of many industrial processes and its low quantification limit also suits the concentrations often found in the working area.
5.6 The segregating sampling device pertaining to this proposed test method physically separates gas and aerosol allowing isocyanate concentrations in both physical states to be obtained, thus helping in the selection of ventilation systems and personal protection.
1.5 The range of application of this test method, utilizing UV and a fluorescence detector, is validated for 0.029 to 1.16 μg of monomer 2,4- and 2,6-TDI/2.0 mL of desorption solution, which corresponds to concentrations of 0.002 to 0.077 mg/m3 of TDI based on a 15-L air sample. This corresponds to 0.28 to 11 ppb(V) and brackets the established TLV value of 5 ppb(v).