A review of available sources identified acute toxicity data (LD50, LCLo) for multiple species and routes, and exposure limits (TWA, OEL-STEL). Data sources were selected according to the hierarchy listed in Table 3.1. Toxicity data were selected according to 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. The data of the most preferred route, a four-hour rat LCLo, was selected as the TEEL-3 basis and was scaled to 60-minute equivalent using the ten Berge equation (Section 3.3.4). The TEEL-2 value was derived according to Table 3.5. The OEL-STEL was selected as the TEEL-1.
• TEEL-1 = OEL-STEL (2 ppm, 10 mg/m3; Denmark, Sweden)
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat LCLo (500 ppm/4H)
This review generated TEEL-1 and TEEL-2 values that are inconsistent with Rev. 29A. In Rev. 29A, the TEEL-2 was based on rat TCLo data that was not found in the current review and was therefore derived according to Table 3.5. For the TEEL-1, the OEL-STEL (Denmark, Sweden) was found and used instead of being derived from the TEEL-2 as in the previous revision. The Rev. 29A and current TEEL-3 values and source remain consistent.