A review of available sources did not identify exposure limits or acute toxicity data for ammonium tungstate(VI). Analysts evaluated acute toxicity data (LD50) for a similar chemical, sodium tungstate (CASRN: 13472-45-2) for TEEL development (Section 3.4.6). In addition, analysts evaluated exposure limits (OEL-STELs, OEL-TWAs) for soluble tungsten (CASRN: 7440-33-7). 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 rat oral LD50 for sodium tungstate was selected as the TEEL-3 basis. TEEL-2 was derived according to Table 3.5. The most frequently reported OEL-STEL value for soluble tungsten (as W; 15-minute average, 3 mg/m3) was selected as the TEEL-1 basis and a compound adjustment factor was applied (Section 3.2.2).
• PAC-1 = TEEL-1 = MW-adjusted OEL-STEL (as W, 3 mg/m3)
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Rat oral LD50 (sodium tungstate, CASRN: 13472-45-2; 1190 mg/kg)
This review generated PAC values inconsistent with Rev. 29A. The Rev. 29A TEEL-1 basis was the MW-adjusted TLV-STEL for tungsten (CASRN: 7440-33-7), from which the TEEL-2 and TEEL-3 were derived (Table 3.5). The current TEEL-3 basis is a rat oral LD50 for a similar chemical (sodium tungstate, CASRN: 13472-45-2), the TEEL-2 was derived from the TEEL-3 (Table 3.5), and the TEEL-1 basis is a MW-adjusted OEL-STEL for soluble tungsten (as W, CASRN: 7440-33-7).