Polychlorinated biphenyls (PCBs) are a group of chemical congeners with varying percentages of chlorination. A review of available sources identified the following exposure limits (STEL, TWAs) and a mouse oral acute toxicity data (LD50). 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 mouse oral LD50 was selected as the TEEL-3 basis. The TEEL-2 value was derived according to Table 3.5. The OEL-STEL (Germany AGS, inhalable fraction, 15-minute) was selected as the TEEL-1.
• PAC-1 = TEEL-1 = OEL-STEL (Germany AGS, 0.024 mg/m3)
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Mouse oral LD50 (1900 mg/kg)
This review generated PAC values inconsistent with Rev. 29A. The Rev. 29A TEEL-3 basis was a rat oral LD50 not found during this review. Instead, the current TEEL-3 basis is an available mouse oral LD50. The Rev. 29A and current TEEL-2 use the same methodology, with differences due to the change in TEEL-3. The Rev. 29A TEEL-1 was derived from the TEEL-2, while the current TEEL-1 is an OEL-STEL (see Table 3.5, note).