RIFM fragrance ingredient safety assessment, 2-cyclohexylcyclohexanone, CAS Registry Number 90-42-6

Summary: The existing information supports the use of this material as described in this safety assessment. 2-Cyclohexylcyclohexanone was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data and read-across to 2-tert-butylcyclohexanone (CAS # 1728-46-7) show that 2-cyclohexylcyclohexanone is not expected to be genotoxic. Data on read-across material 2-sec-butylcyclohexanone (CAS # 14765-30-1) provide a calculated margin of exposure (MOE) > 100 for the repeated dose toxicity and reproductive toxicity endpoints. The skin sensitization endpoint was completed using the dermal sensitization threshold (DST) for non-reactive materials (900 μg/cm²); exposure is below the DST. The phototoxicity/photoallergenicity endpoints were evaluated based on UV spectra; 2-cyclohexylcyclohexanone is not expected to be phototoxic/photoallergenic. The local respiratory toxicity endpoint was evaluated using the threshold of toxicological concern (TTC) for a Cramer Class II material, and the exposure to 2-cyclohexylcyclohexanone is below the TTC (0.47 mg/day). The environmental endpoints were evaluated; 2-cyclohexylcyclohexanone was found not to be persistent, bioaccumulative, and toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards, and its risk quotients, based on its current volume of use in Europe and North America (i.e., Predicted Environmental Concentration/Predicted No Effect Concentration [PEC/PNEC]), are <1.