A review of available sources did not identify exposure limits or acute toxicity data for iodic acid. Instead, the similar compounds (iodine, bromic acid, chloric acid, nitric acid) were reviewed and evaluated for TEEL development. From the chemical compounds reviewed, nitric acid was selected based on chemical similarity (reactive oxidant) and available, published exposure limits and acute toxicity data (Section 3.4.6). The IDLH for nitric acid was selected as the TEEL-3; this value is slightly less conservative than the AEGL-3, which analysts considered a compromise due to differences in corrosive properties. TEELs reported in mg/m3 values account for the differences in molecular weight between nitric acid and iodic acid. 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 = IDLH (1990, nitric acid CASRN: 7697-37-2, 100 ppm)
This review generated TEEL values that are inconsistent with Rev. 29A. The Rev. 29A TEEL-3 was the 1990 IDLH for iodine (CASRN: 7553-56-2), from which the TEEL-2 and TEEL-1 were derived. The Rev. 29A TEEL values in units of ppm are correct, while the mg/m3 values are incorrectly published as the same values without conversion. Instead, the current review has selected a more analogous chemical compound and corresponding IDLH values.