A review of available sources did not identify exposure limits or acute toxicity data for dicyclohexyl. Instead, analysts reviewed acute toxicity data (LCLo, LC50) for structurally similar compound, methylcyclohexane (CASRN: 108-87-2). 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. Inhalation exposures were scaled to 60-minute equivalents using the ten Berge equation (Section 3.3.4). The most preferred source, a mouse LC50, was selected as the TEEL-3 basis.
• PAC-1 = TEEL-1 = TEEL-2/11
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Mouse LC50 (methylcyclohexane, CASRN: 108-87-2; 41500 mg/m3/2H)
This review generated PAC values that are inconsistent with Rev. 29A. The Rev. 29A TEEL-1 basis was a TLV-TWA for particles not otherwise specified (Section 3.5.2), from which the TEEL-2 and TEEL-3 were derived (Table 3.5). The current TEEL-3 is acute toxicity (LC50) for a structurally similar chemical, methylcyclohexane (Section 3.4.6, CASRN: 108-87-2), from which from which the TEEL-2 and TEEL-1 were derived (Table 3.5). the current TEEL-1 was derived from the TEEL-2 (Table 3.5).