A review of available sources identified exposure limits (TWAs, STELs, PEL-C, IDLH) and acute toxicity data for manganese. 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. In addition, analysts evaluated the available health hazard data to determine an appropriate magnitude for TEELs. The GHS health hazard code (H319, Category 2) for manganese corresponds to an approximate HHR between 2 and 3 (TEEL-3 = 790 mg/m3 and TEEL-3= 79 mg/m3, respectively). 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, and the estimated TEEL-3 range from reported GHS health hazards, analysts selected the 1994 IDLH was the TEEL-3. The PEL-C was selected as the TEEL-2. The PEL-STEL was selected as the TEEL-1.
• TEEL-1 = PEL-STEL (3 mg/m3)
• TEEL-2 = PEL-C (5 mg/m3)
• TEEL-3 = IDLH (1994, 500 mg/m3)
This review generated TEEL-2 and TEEL-1 values consistent with Rev. 29A. The Rev. 29A and current TEEL-3 values are inconsistent. The Rev. 29A TEEL-3 was the 1990 IDLH, while analysts recommend the use of the 1994 IDLH due to its inclusion of inhalation acute toxicity data. The 1994 IDLH was used according to handbook guidelines (Section 4.2-4.3).