A review of available data sources identified the following: rat oral LDLo and mouse skin (insoluble) LD50 toxicity data, and a MAK-TWA exposure limit. 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 MAK-TWA exposure limit is used to calculate TEEL-1. The toxicity data was considered next, and of the available TEEL-3 starting points, LD50 is the more preferred dose type. However, rat and oral administration is the preferable species and route. Therefore, the rat oral LDLo data was selected as the TEEL-3 basis. The dose was converted to mg/kg using a density of 0.86 g/mL. TEEL-2 was derived from TEEL-3, according to Table 3.5.
• TEEL-1= MAK-TWA (10 ppm) x 3
• TEEL-2= TEEL-3/6
• TEEL-3= Rat oral LDLo (10 mL/kg converted to 8600 mg/kg)
This review generated values that are less conservative than those reported in Rev. 29A. Previously, TEEL-1 was generated from TEEL-2 using the adjustment factors. Independent data is preferable, if credible. Although the methodology is the same for TEEL-3 between the two versions, the rat oral LDLo data used in Rev. 29A was not found during current research.