A review of available sources identified a TLV-TWA for iodine and iodides (CASRN: 7553-56-2,) and mouse and rat acute toxicity data (LDLo, LD50). Data sources were evaluated 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 species and route, a rat oral LD50, was selected as the TEEL-3 basis. The TLV-TWA was considered as a TEEL-1 basis; however, it was unclear from its definition and magnitude if it applied to this chemical. The TEEL-2 and TEEL-1 were derived according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat oral LD50 (3118 mg/kg)
This review generated TEELs that are significantly less conservative than those in Rev. 29A. The Rev. 29A TEEL-3 basis, a rat intravenous LDLo, is a less preferred source (LD50 > LDLo) and route (oral > intravenous)¬ than the current basis. The Rev. 29A and current TEEL-2 methodology is consistent, however the current value is higher due to the change in TEEL-3 basis.