A review of available sources identified acute toxicity data (LD50, LC50) for various species and routes, and exposure limits (OEL-TWAs, 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 most preferred exposure data, a 2-hour mouse LC50, was selected as the TEEL-3 basis and was scaled down to a 60-minute equivalent using the ten Berge equation (Section 3.3.4). The TEEL-2 was derived according to Table 3.5. Although STEL values are more preferable than TWAs (Table 3.1), using this value resulted in TEEL-1 > TEEL-2 and TEEL-3; therefore, it was not selected for TEEL development. Instead, the most conservative OEL-TWA was selected as the TEEL-1 basis.
• PAC-1 = TEEL-1 = OEL-TWA (10 mg/m3; Latvia) x 3
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Mouse LC50 (6600 mg/m3/2H)
This review generated PAC values inconsistent with Rev. 29A. The Rev. 29A TEEL-3 basis was a rat oral LD50, while the current basis is a more preferable data type (LC50 > LD50, Table 3.1). The Rev. 29A TEEL-2 basis was rat intraperitoneal TDLo that was not identified during this investigation. Instead, the current TEEL-2 was derived from the TEEL-3 (Table 3.5). The Rev. 29A TEEL-1 was derived from the TEEL-2 (Table 3.5), while the current TEEL-1 basis is an exposure limit, OEL-TWA (Latvia).