A review of available sources identified the following: an IDLH (1990 and 1994), a TLV-TWA, and acute toxicity data (LC50, LD50) for several species and routes. Data sources were selected according to the hierarchy listed in Table 3.1. Toxicity data are based on the type of exposure, species, and route according to the hierarchies stated in Sections 3.3.1, 3.3.2, and evaluated using factors in Tables 3.2, 3.3, and 3.4. Inhalation exposures were scaled to 60-minute equivalents using the ten Berge equation (Section 3.3.4). The 1990 IDLH was based on the IDLH values of a similar chemical, dimethyl phthalate (CASRN: 131-11-3) due to a lack of data. The 1994 IDLH was developed from acute inhalation toxicity data in animals for dibutyl phthalate. Considering this, and the source priority lists in Table 3.1, the 1994 IDLH was selected as the TEEL-3. The available human oral TDLo toxicity was evaluated as a TEEL-2 source, however it resulted in a TEEL-2 less than the TLV-TWA x 3 (Section 3.4.2), therefore it was not selected as a TEEL-2 basis. Instead, the TEEL-2 values were derived according to Table 3.5. The TLV-TWA was selected as the TEEL-1 basis.
• TEEL-1 = TLV-TWA (5 mg/m3) x 3
• TEEL-2 = TEEL-3/6
• TEEL-3 = IDLH (1994, 4000 mg/m3)
This review generated TEEL-3 and TEEL-2 values inconsistent with Rev. 29A. The Rev. 29A TEEL-3 basis was the 1990 IDLH, which was based on an analogous chemical. The current TEEL-3 is the 1994 IDLH, which was developed from acute inhalation toxicity in animals for dibutyl phthalate. The 1994 IDLH was used according to Handbook guidelines (Section 4.2-4.3). The difference in TEEL-2 values is due to the change in TEEL-3. The Rev. 29A and current TEEL-1 basis and values are consistent.