A review of available sources identified acute toxicity data (LD50) for several species and routes. In addition, analysts evaluated exposure limits (IDLH, ceiling limits, TWAs) for manganese compounds (CASRN: 7439-96-5). Data sources were selected according to the hierarchy listed in Table 3.1. Toxicity data were evaluated using factors in Tables 3.2, 3.3, and 3.4. The manganese IDLH was considered as a TEEL-3 basis, however it was not selected due to the available of acute toxicity data for manganese(II) chloride. Instead, the lowest dose rat oral LD50 was selected as the TEEL-3 basis. The manganese PEL-C was selected as the TEEL-2 and a compound adjustment factor was applied per Section 3.2.2. The manganese PEL-STEL was selected as the TEEL-1 basis and a compound adjustment factor was applied per Section 3.2.2.
• PAC-1 = TEEL-1 = MW-adjusted PEL-STEL (manganese compounds, CASRN: 7439-96-5; 3 mg/m3)
• PAC-2 = TEEL-2 = MW-adjusted PEL-C (manganese, CASRN: 7439-96-5; 5 mg/m3)
• PAC-3 = TEEL-3 = Rat oral LD50 (236 mg/kg)
This review generated PAC-2 and PAC-1 values consistent with Rev. 29A and a PAC-3 inconsistent. The Rev. 29A and current TEEL-2 and TEEL-1 sources and methodologies are consistent. The Rev. 29A TEEL-3 was derived from the TEEL-2, while the current basis is a rat oral LD50, a more preferred source (Section 3.4).