A review of available sources identified acute toxicity data (LD50, LDLo) for several species and routes. In addition, analysts evaluated exposure limits for fluorides (no CASRN; IDLH, TWA). 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 fluoride IDLH was considered as a TEEL-3 basis; however, analysts instead selected acute toxicity data for lithium fluoride. Of the available rat oral LD50, analysts selected the most recent (Section 3.3.1). The TEEL-2 was derived according to Table 3.5. Analysts did not find chemical specific TEEL-1 sources; considering this, analysts selected the TLV-TWA for fluorides and applied a compound adjustment factor (Section 3.2.2).
• PAC-1 = TEEL-1 = MW-adjusted TLV-TWA (fluorides, 2.5 mg/m3) x 3
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Rat oral LD50 (706 mg/kg)
This review generated PAC-3 and PAC-2 values inconsistent with Rev. 29A, and a consistent PAC-1 value. The Rev. 29A TEEL-3 basis was derived using MW-adjusted IDLH as fluorides, while the current TEEL-3 basis is acute toxicity data specific to lithium fluoride. The Rev. 29A and current TEEL-2 use the same methodology, with differences due to the change in TEEL-3. The Rev. 29A and current TEEL-1 values, source, and methodology are consistent.