A review of available sources did not identify exposure limits, acute toxicity, or health hazard ratings for cesium metaborate. Analysts evaluated similar chemicals, specifically lithium metaborate, anhydrous (CASRN: 13453-69-5), potassium metaborate (CASRN: 13709-94-9), and sodium metaborate (CASRN: 7775-19-1). Of these, only sodium metaborate reported acute toxicity data, a rat oral LD50, which was selected as the TEEL-3 basis and evaluated using factors in Tables 3.2, 3.3, and 3.4 (Section 3.4.6). TEEL-2 and TEEL-1 values were derived according to Table 3.5.
• PAC-1 = TEEL-1 = TEEL-2/11
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Rat oral LD50 (sodium metaborate, CASRN: 7775-19-1, 2330 mg/kg)
This review generated PAC-3 and PAC-2 values consistent with Rev. 29A. The Rev. 29A and current PAC-1 values are inconsistent. The Rev. 29A TEEL-1 basis is a weight adjusted inorganic borate compounds TLV-STEL, which was not applicable to this compound; instead, analyst derived the TEEL-1 from the TEEL-2 (Table 3.5).