Dinitrotoluene is a mixture of several isomers, consisting of approximately 80% 2,4-dinitrotoluene, 20% 2,6-dinitrotoluene and <5% 3,4-, 2,3- and 2,5-dinitrotoluenes. A review of available sources identified the following: IDLH and TLV-TWA exposure data for this substance. Data sources were selected according to the hierarchy listed in Table 3.1. Both the original and revised IDLH values were considered for TEEL-3 basis. The original IDLH (1990) basis was cat oral LDLo toxicity data, while the revised IDLH (1994) uses the exposure limits developed for a similar chemical, dinitrobenzene. The toxicological profile of this isomer mixture is expected to reflect the properties of its main constituents, 2,4-dinitrotoluene and 2,6-dinitrotoluene. Recent TEEL reviews have suggested that although 2,4-dinitrotoluene (CASRN: 121-14-2) and 2,6-dinitrotoluene (CASRN: 606-20-2) have different TEEL-3 values (53 mg/m3 and 12 mg/m3, respectively) they are similar in magnitude to the revised IDLH (50 mg/m3). Given that this substance is a mixture of dinitrotoluene isomers, as described above, and considering the TEEL-3 values of its main constituents, the revised IDLH (1994) value was selected as the TEEL-3. The TEEL-2 was derived according to Table 3.5. The TLV-TWA value was selected as the TEEL-1 basis.
• TEEL-1 = TLV-TWA (0.2 mg/m3) x 3
• TEEL-2 = TEEL-3/6
• TEEL-3 = IDLH (1994, 50 mg/m3)
This review generated TEEL-3 and TEEL-2 values that are more conservative than Rev. 29A. The Rev. 29A TEEL-3 was the original IDLH value (1990), while the current review selected the revised IDLH (1994). The 1994 IDLH was used according to Handbook guidelines (Section 4.2-4.3). The Rev. 29A and current TEEL-1 values and source are consistent. The Rev. 29A and current TEEL-2 methodology used are consistent, with differences in value due to the change in TEEL-3.