A review of available sources did not identify exposure limits or acute toxicity for manganese carbonate. Instead, analysts evaluated exposure limits of manganese compounds (CASRN: 7439-96-5, IDLH, ceiling limits, STELs, TWAs) for TEEL development. Data sources were selected according to the hierarchy listed in Table 3.1. The 1990 and 1994 IDLH were compared; the 1990 IDLH was derived from the PEL-TWA, while the 1994 IDLH includes animal inhalation acute toxicity data. Considering this, analysts selected the 1994 IDLH as the TEEL-3 basis. The PEL-C was selected as the TEEL-2. The PEL-STEL was selected as the TEEL-1. A compound adjustment factor was applied to 1994 IDLH, PEL-C, and PEL-STEL (Section 3.2.2).
• PAC-1 = TEEL-1 = MW-adjusted PEL-STEL (manganese, 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 = MW-adjusted IDLH (1994, manganese, CASRN: 7439-96-5; 500 mg/m3)
This review generated PAC-2 and PAC-1 values consistent with Rev. 29A and a PAC-3 value inconsistent. The Rev. 29A and current TEEL-2 and TEEL-1 use the same sources and methodologies. The Rev. 29A TEEL-3 was derived from the TEEL-2. The current TEEL-3 basis is a weight adjusted 1994 manganese IDLH, due to its inclusion of inhalation acute toxicity data. The 1994 IDLH was used according to handbook guidelines (Section 4.2-4.3).