A review of available sources identified exposure limits (OEL STEL and TWA) and acute toxicity data (LD50, LDLo) for several/numerous species and routes. In addition, analysts evaluated exposure limits (IDLH, REL-C) for inorganic arsenic compounds (CASRN: 7440-38-2) for TEEL development (Section 3.4.6). 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. The most current and most preferred route toxicity data, a rat oral LD50, was selected as the TEEL-3 basis. The REL-C for arsenic, inorganic compounds (CASRN: 7440-38-2) was evaluated for the TEEL-2 but was not selected since it was less than the chemical-specific OEL-TWA x 3 (Table 3.5, Note). Instead, the TEEL-2 was derived according to Table 3.5. The available OEL-STEL was evaluated, and it was determined that it is not appropriate for TEEL development; instead, the OEL-TWA (Sweden) was selected as the TEEL-1 basis. The OEL-TWA is reported “as Arsenic (As)”, therefore a compound adjustment factor was applied (Section 3.2.2).
• PAC-1 = TEEL-1 = MW-adjusted OEL-TWA (0.01 mg/m3) x 3
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Rat oral LD50 (48 mg/kg)
This review generated PAC values inconsistent with Rev. 29A. The Rev. 29A TEEL-3 basis was a weight adjusted arsenic IDLH, while the current TEEL-3 basis is a chemical specific rat oral LD50. The Rev. 29A and current TEEL-2 use the same methodology, with differences due to the change in TEEL-3. The Rev. 29A TEEL-1 basis was derived from the TEEL-2, while the current TEEL-1 basis is a weight adjusted OEL-TWA (Section 3.4.2).