A review of available sources did not identify exposure limits or acute toxicity data for anhydrous lithium metaborate. The GHS health hazards reported range from Category 1 to 4, indicating a mid- to high level hazard level (H318, Category 1; H315, Category 2; H336, Category 3, H302, Category 4), approximately equivalent to an HHR between 3 and 2 (Section 3.4.5; PAC-3 = TEEL-3 = 79 and 790 mg/m3, respectively). Analysts also evaluated similar chemicals, specifically potassium metaborate (CASRN: 13709-94-9), and sodium metaborate (CASRN: 7775-19-1). Of these, 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). This TEEL value is within the range indicated by GHS hazards. 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, and a PAC-1 value inconsistent with Rev. 29A. The Rev. 29A TEEL-1 basis is a weight adjusted TLV-STEL, reportedly for "inorganic borate compounds“; analysts determined this value is restricted to specific borates containing BO3, BO4 and BO5, and is not applicable to general inorganic borate compounds. Instead, analysts derived the TEEL-1 from the TEEL-2 (Table 3.5).