A review of available data sources identified the following: rat and mouse oral LD50, mouse intraperitoneal LD50, and rat LC50 toxicity data. Data sources were selected according to the hierarchy listed in Table 3.1. Toxicity data were selected according to the type of exposure, species, and route hierarchies stated in Sections 3.3.1, 3.3.2. The LC50 rat data is the most preferred data species and route. However, it is also the oldest (1975) and does not list the dose duration. The next most preferred toxicity data, by species and route, is a rat oral LD50 which is also more recent (1984). Of these, the rat oral LD50 was selected as the TEEL-3 basis because it is a complete record, is more current by greater than 5 years, and results in a more conservative TEEL-3 (Section 3.3.1). The TDLo was evaluated, but not selected because the toxicity end point did not meet the criteria outlined in the handbook (Section 3.2.2). Instead, 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 oral LD50 (2383 mg/kg)
This review generated values that are inconsistent than those reported in Rev. 29A. In Rev. 29A, the TEEL-3 basis was a rat intraperitoneal LD50, however this review selected a TEEL-3 basis of a rat oral LD50 as the most current and preferred route of administration. The Rev. 29A TEEL-2 basis of a rat oral TDLo did not meet TEEL toxicity end-point criteria and was instead derived from the current TEEL-3.