A review of available sources identified acute toxicity data (LDLo) for various routes (intraperitoneal, oral) and species (rat, dog). In addition, exposure limits (TWAs, STELs, IDLHs) for lead (CASRN: 7439-92-1) were evaluated for TEEL development. 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. Analysts selected the 1990 lead IDLH (CASRN: 7439-92-1) as the TEEL-3 basis and a compound adjustment factor was applied (Section 3.2.2). Note that this resulted in a TEEL-3 comparable to the dog oral LDLo (TEEL-3 = 770 mg/mg3). The TEEL-2 was derived according to Table 3.5. The MAK-STEL for inorganic lead compounds (CASRN: 7439-92-1, Germany DGF, inhalable fraction, 15-minute) was selected as the TEEL-1 and a compound adjustment factor was applied (Section 3.2.2).
• PAC-1 = TEEL-1 = MW-adjusted MAK-STEL (inorganic lead compounds, CASRN: 7439-92-1; 0.032 mg/m3)
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = MW-adjusted IDLH (1990, lead, CASRN: 7439-92-1; 700 mg/m3)
This review generated PAC-3 and PAC-2 values consistent with Rev. 29A and a PAC-1 inconsistent. The Rev. 29A and current TEEL-3 and TEEL-2 use the same source and methodologies. The Rev. 29A TEEL-1 basis was a weight adjusted TLV-TWA, while the current TEEL-1 is a weight adjusted MAK-STEL (Table 3.1).