A review of available sources identified a rat inhalation study for this chemical (1-nitropyrene). In addition, analysts evaluated acute toxicity and exposure limits for a similar chemical pyrene (C16H10, CASRN: 129-00-0; Section 3.4.6). 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 determined that the rat inhalation study for 1-nitropyrene data was not appropriate for TEEL development because it did not report adverse effects. Instead, the rat LC50 for pyrene was selected as the TEEL-3 basis (Section 3.4.6); no duration was reported, therefore a 240-minute duration was assumed, and the TEEL was scaled to 60-minute equivalent using the ten Berge equation (Sections 3.3.2 and 3.3.4). The LOC for pyrene was selected as the TEEL-2 (Section 3.4.6). The TEEL-1 value was derived according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = LOC (pyrene, CASRN: 129-00-0; 0.0017 g/m3)
• TEEL-3 = Rat LC50 (pyrene, CASRN: 129-00-0, 170 mg/m3/4H assumed)
This review generated TEEL values inconsistent with Rev. 29A. The Rev. 29A TEEL-2 basis was rat TCLo study with a 360-min exposure. The Rev. 29A TEEL-3 was derived from this TEEL-2. The current TEEL-3 basis is a rat LC50 for a similar chemical (pyrene, CASRN: 129-00-0). The current TEEL-2 was derived from this TEEL-3. The Rev. 29A and current TEEL-1 use the same methodology (Table 3.5), with differences due to the change in TEEL-2.