A review of available sources identified acute toxicity data (LD50, LC50) from various species (rat, mouse) and routes (oral, intraperitoneal, inhalation). 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. Although inhalation is the most preferred route, the acute inhalation data (rat LC50) did not have a duration reported; therefore, this data was not selected for TEEL development (Section 3.3.1). As such, the next most preferred species and route data, a rat oral LD50, was selected as the TEEL-3 basis. TEEL-1 and TEEL-2 values were derived according to Table 3.5.
• PAC-1 = TEEL-1 = TEEL-2/11
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Rat oral LD50 (426 mg/kg)
This review generated PAC values inconsistent with Rev. 29A. The Rev. 29A and current TEEL-3 are both based on rat oral LD50 toxicity data; however, this review used a more conservative dose. The Rev. 29A TEEL-2 value was based on a rat dermal TDLo that was not found in this review. Instead, the current TEEL-2 was derived from the TEEL-3 (Table 3.5). The Rev. 29A and current TEEL-1 methodology remains consistent, with the differences in values due to the change of the TEEL-2 basis.