A review of available sources identified the following: OEL-TWA (Latvia), man oral TDLo, rat LC50, and oral LD50 toxicity data for multiple species (rat, mouse, guinea pig). 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 most preferred species and route, a rat LC50, was selected as the TEEL-3 basis and was scaled to a 60-minute equivalent using the ten Berge equation (Section 3.3.4). A man oral TDLo (143 mg/kg) with hazardous toxic endpoints of nausea, vomiting, acute renal failure, and acute tubular necrosis was evaluated as the TEEL-2 basis; however, it was not selected because the result, 86 mg/m3, was significantly higher than the recommended TEEL-3 value. Similarly, the OEL-TWA (1 mg/m3) was considered as the TEEL-1 basis but was not selected since the result would be a value greater than the TEEL-2 value. TEEL-2 and TEEL-1 values were derived according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat LC50 (230 mg/m3/4H)
This review generated TEEL values inconsistent with Rev. 29A. The Rev. 29A and current TEEL-3 basis and methodology are consistent (rat LC50/4H); therefore, differences in the value may be due to the current source being a lower dose. The TEEL-2 and TEEL-1 methodology remain consistent, with the changes in values due to the possible dose differences.