A review of available sources identified the following acute toxicity data (LDLo) and exposure limits for indium compounds (TWAs, CASRR: 7440-74-6). 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. When considering the toxicity of indium(III) oxide, analysts noted that the primary reported health hazard is the accumulation of indium oxide particles in the lungs (sub-chronic/chronic). The most preferred route and species toxicity data, a mouse oral LDLo, was selected as the TEEL-3 basis. A molecular weight adjusted indium TLV-TWA was considered as a TEEL-1, however it was determined to be overly conservative. TEEL-1 and TEEL-2 values were derived according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Mouse oral LDLo (10 g/kg)
This review generated inconsistent TEEL values with Rev. 29A. The Rev. 29A TEEL-1 basis was a MW-adjusted TLV-TWA. The Rev 29A, TEEL-2 basis was a rat TCLo not found during this review; the TEEL-3 was derived from this value. The current TEEL-3 basis is a mouse LDLo, from which TEEL-2/TEEL-1 values were derived. The current TEEL values are significantly higher than those in Rev. 29A; this is expected given that 1) indium(III) oxide is more stable than indium, and 2) indium(III) oxide particle accumulation is its primary hazard (sub-chronic/chronic toxicity effects).