A review of available sources identified the following: acute toxicity data for beryllium nitrate and exposure limits (PEL-TWA, TLV-TWA, ERPGs) for beryllium (CASRN: 7440-41-7). 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. Although the analysts did evaluate the available acute toxicity data for beryllium nitrate, the ERPGs for beryllium were selected as the TEEL-3 and TEEL-2 values. Factors considered include: the most preferred route and species, a mouse intravenous LD50, would result in a TEEL-3 of 0.68 mg/m3 that is comparable to the ERPG-3 value, but 2) is a less preferred source (Table 3.1) for the TEEL-3. The TLV-TWA for beryllium was selected as the TEEL-1, and a compound adjustment factor was applied.
• TEEL-1 = MW-adjusted TLV-TWA (beryllium; CASRN 7440-41-7, 0.00005 mg/m3) x 3
• TEEL-2 = EPRG-2 (beryllium; CASRN 7440-41-7, 0.025 mg/m3)
• TEEL-3 = EPRG-3 (beryllium; CASRN 7440-41-7, 0.1 mg/m3)
This review generated TEEL values inconsistent with Rev. 29A. The Rev. 29A and current TEEL-3 and TEEL-2 sources, ERPGs, are consistent; however, the Rev. 29A TEELs applied a molecular-weight adjustment, while the current values are not adjusted, in accordance with Section 3.2.2. The Rev. 29A TEEL-1 was derived from the TEEL-2 (Table 3.5), while the current TEEL-1 basis is a molecular weight adjusted TLV-TWA exposure limit.