Update to RIFM fragrance ingredient safety assessment, β-naphthyl isobutyl ether, CAS Registry Number 2173-57-1.

The existing information supports the use of this material as described in this safety assessment. β-Naphthyl isobutyl ether was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, photoirritation/photoallergenicity, skin sensitization, and environmental safety. Target data and data from read-across analog β-naphthyl methyl ether (CAS # 93-04-9) show that β-naphthyl isobutyl ether is not expected to be genotoxic. Data on β-naphthyl isobutyl ether provide a calculated Margin of Exposure (MOE) > 100 for the repeated dose toxicity endpoint. Data on read-across analog β-naphthyl methyl ether (CAS # 93-04-9) provide a calculated MOE >100 for the reproductive toxicity endpoint. Data show that there are no safety concerns for β-naphthyl isobutyl ether for skin sensitization under the current declared levels of use. The photoirritation/photoallergenicity endpoints were evaluated based on ultraviolet/visible (UV/Vis) spectra; β-naphthyl isobutyl ether is not expected to be photoirritating/photoallergenic. The local respiratory toxicity endpoint was evaluated using the Threshold of Toxicological Concern (TTC) for a Cramer Class III material, and the exposure to β-naphthyl isobutyl ether is below the TTC (0.47 mg/day). The environmental endpoints were evaluated; β-naphthyl isobutyl ether was found not to be Persistent, Bioaccumulative, and Toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards, and its risk quotients (RQs), based on its current volume of use (VoU) in Europe (EU), North America (NA), Asia-Pacific (AP), and South America (SA) (i.e., Predicted Environmental Concentration/Predicted No Effect Concentration [PEC/PNEC]), are <1.