The Path to UVCB Ecological Risk Assessment: Grappling with Substance Characterization

Substances of unknown or variable composition, complex reaction products, and biological materials (UVCBs) pose a unique challenge to regulators and to product registrants, who are required to characterize their fate, exposure, hazard, and potential risks to human health and the environment. To address these challenges and ensure an efficient and fit-for-purpose process, it is proposed that the ecological risks of UVCBs be assessed following a tiered strategy. The development of this approach required exploring how substance composition ties into hazard and exposure information and determining the extent to which a UVCB needs to be characterized to ensure a robust risk assessment. The present study highlights the key aspects of this new method. It presents how a tiered substance characterization approach can be integrated into broader UVCB risk-assessment schemes to encourage an examination of data needs before a full substance characterization is performed. The first tier of the characterization process, Tier 0, is a fundamental step that includes data from basic, lower-resolution compositional analyses. Tier 0 assessments can be used to inform hazard and exposure for any substance of interest. The need for more sophisticated, higher-tier characterization is determined by the level of uncertainty of the risk assessment. The next step will integrate a tiered exposure assessment into the characterization scheme featured in the present study, to create a more complete risk-assessment framework. Environ Toxicol Chem 2022;41:2649-2657. © 2022 Her Majesty the Queen in Right of Canada, Health and Environmental Sciences Institute and The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada.

RIFM low-exposure fragrance ingredients safety assessment

The existing information supports the use of these materials as described in this safety assessment. The 167 materials identified in this assessment were evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Target data, read-across analogs and TTC show that these materials are not expected to be genotoxic. The repeated dose, reproductive, and local respiratory toxicity endpoints were evaluated using the TTC for their respective Cramer Classes (see Fig. 1 below) and the exposure to these materials is below the TTC. The skin sensitization endpoint was completed using the DST for non-reactive and reactive materials (900 μg/cm² and 64 μg/cm², respectively); exposures are below the DST. The phototoxicity/photoallergenicity endpoints were evaluated based on UV spectra; these materials are not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; the materials were found not to be PBT as per the IFRA Environmental Standards, and their risk quotients, based on their current volume of use in Europe and North America (i.e., PEC/PNEC), are <1.

RIFM fragrance ingredient safety assessment, 3,7-dimethyl-1,3,6-octatriene, CAS registry number 13877-91-3

The existing information supports the use of this material as described in this safety assessment. 3,7-Dimethyl-1,3,6-octatriene was evaluated for genotoxicity, repeated dose toxicity, developmental and reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from 3,7-dimethyl-1,3,6-octatriene and read-across analog myrcene (β-myrcene; CAS # 123-35-3) show that 3,7-dimethyl-1,3,6-octatriene is not expected to be genotoxic and provide a calculated margin of exposure (MOE) >100 for the repeated dose toxicity and developmental and reproductive toxicity endpoints. The skin sensitization endpoint was completed using the dermal sensitization threshold (DST) for non-reactive materials (900 μg/cm 2 ); exposure is below the DST. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet (UV) spectra; 3,7-dimethyl-1,3,6- octatriene 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 I material, and the exposure to 3,7-dimethyl-1,3,6-octatriene is below the TTC (1.4 mg/day). The environmental endpoints were evaluated; 3,7-dimethyl-1,3,6- octatriene 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 oncentration/Predicted No Effect Concentration [PEC/PNEC]), are <1.

RIFM fragrance ingredient safety assessment, p-tolualdehyde, CAS Registry Number 104-87-0

The existing information supports the use of this material as described in this safety assessment. p-Tolualdehyde was evaluated for genotoxicity, repeated dose toxicity, developmental and reproductive toxicity, local respiratory toxicity, phototoxicity, skin sensitization potential, and environmental safety. Data from read-across analog benzaldehyde (CAS # 100-52-7) show that p-tolualdehyde is not expected to be genotoxic. Data from read-across analog cuminaldehyde (CAS # 122-03-2) provided p-tolualdehyde a No Expected Sensitization Induction Level (NESIL) of 1100 μg/cm² for the skin sensitization endpoint. The repeated dose toxicity, developmental and reproductive toxicity, and local respiratory toxicity endpoints were completed using the threshold of toxicological concern (TTC) for a Cramer Class I material, and the exposure to p-tolualdehyde is below the TTC (0.03 mg/kg/day, 0.03 mg/kg/day, and 1.4 mg/day, respectively). The phototoxicity/photoallergenicity endpoints were evaluated based on data from read-across analog 4-ethylbenzaldehyde (CAS # 4748-78-1); p-tolualdehyde is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; p-tolualdehyde 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.

Improving the Environmental Risk Assessment of Substances of Unknown or Variable Composition, Complex Reaction Products, or Biological Materials

Substances of unknown or variable composition, complex reaction products, or biological materials (UVCBs) pose unique risk assessment challenges to regulators and to product registrants. These substances can contain many constituents, sometimes partially unknown and/or variable, depending on fluctuations in their source material and/or manufacturing process. International regulatory agencies have highlighted the difficulties in characterizing UVCBs and assessing their toxicity and environmental fate. Several industrial sectors have attempted to address these issues by developing frameworks and characterization methods. Based on the output of a 2016 workshop, this critical review examines current practices for UVCB risk assessment and reveals a need for a multipronged and transparent approach integrating whole-substance and constituent-based information. In silico tools or empirical measurements can provide information on discrete and/or blocks of UVCB constituents with similar hazard properties. Read-across and/or whole-substance toxicity and fate testing using adapted emerging methods can provide whole-substance information. Continued collaboration of stakeholders representing government, industry, and academia will facilitate the development of practical testing strategies and guidelines for addressing regulatory requirements for UVCBs. Environ Toxicol Chem 2020;39:2097-2108. © 2020 Health and Environmental Sciences Institute. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

RIFM fragrance ingredient safety assessment, 2-decanone, CAS Registry Number 693-54-9

The existing information supports the use of this material as described in this safety assessment. 2-Decanone was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from read-across analog 2-heptanone (CAS # 110-43-0) show that 2-decanone is not expected to be genotoxic. Data on read-across analog 2-heptanone (CAS # 110-43-0) 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 ultraviolet (UV) spectra; 2-decanone is not expected to be phototoxic/photoallergenic. For the local respiratory endpoint, a calculated MOE >100 was provided by the read-across analog 4-methyl-2-pentanone (CAS # 108-10-1). The environmental endpoints were evaluated; for the hazard assessment based on the screening data, 2-decanone is not persistent, bioaccumulative, and toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards. For the risk assessment, 2-decanone was not able to be risk screened as there were no reported volumes of use for either North America or Europe in the 2015 IFRA Survey.

RIFM fragrance ingredient safety assessment, 2-phenylpropionaldehyde, CAS Registry Number 93-53-8

The existing information supports the use of this material as described in this safety assessment. 2-Phenylpropionaldehyde was evaluated for genotoxicity, repeated dose toxicity, developmental and reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data on read-across analogs 3-phenylbutanal (CAS # 16251-77-7) and isopropylphenylbutanal (CAS # 125109-85-5) show that this material is not expected to be genotoxic. Data from the target material provide a calculated margin of exposure (MOE) >100 for the repeated dose toxicity endpoint and a No Expected Sensitization Induction Level (NESIL) of 380 μg/cm² for the skin sensitization endpoint. The developmental and reproductive toxicity and the local respiratory toxicity endpoints were completed using the threshold of toxicological concern (TTC) for a Cramer Class I material (0.03 mg/kg/day and 1.4 mg/day, respectively). The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet (UV) spectra; 2-phenylpropionaldehyde is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; 2-phenylpropionaldehyde 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.

RIFM fragrance ingredient safety assessment, 3,7-dimethyl-3,6-octadienal, CAS registry number 55722-59-3

The existing information supports the use of this material as described in this safety assessment. 3,7-Dimethyl-3,6-octadienal was evaluated for genotoxicity, repeated dose toxicity, developmental and reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from read-across analog citral (CAS # 5392-40-5) show that 3,7-dimethyl-3,6-octadienal is not expected to be genotoxic and provided a calculated margin of exposure (MOE) >100 for the repeated dose toxicity and developmental and reproductive endpoints. Data from the read-across analog citronellal (CAS # 106-23-0) provided 3,7-dimethyl-3,6-octadienal a No Expected Sensitization Induction Level (NESIL) of 7000 μg/cm² for the skin sensitization endpoint. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet (UV) spectra; 3,7-dimethyl-3,6-octadienal 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 I material, and the exposure to 3,7-dimethyl-3,6-octadienal is below the TTC (1.4 mg/day). The environmental endpoints were evaluated; 3,7-dimethyl-3,6-octadienal 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.

RIFM fragrance ingredient safety assessment, phenylacetaldehyde, CAS Registry Number 122-78-1

The existing information supports the use of this material as described in this safety assessment. The material (phenylacetaldehyde) was evaluated for genotoxicity, repeated dose toxicity, developmental and reproductive toxicity, local respiratory toxicity, phototoxicity, skin sensitization, and environmental safety. Data show that phenylacetaldehyde is not genotoxic and provide a calculated margin of exposure (MOE) > 100 for the repeated dose and developmental and reproductive toxicity endpoints. Data from phenylacetaldehyde provided a No Expected Sensitization Induction Level (NESIL) of 590 μg/cm² for the skin sensitization endpoint. The local respiratory toxicity endpoint was completed using the threshold of toxicological concern (TTC) for a Cramer Class I material, and the exposure to phenylacetaldehyde was below the TTC (0.03 mg/kg/day, 0.03 mg/kg/day, and 1.4 mg/day, respectively). The phototoxicity/photoallergenicity endpoint was completed based on data and ultraviolet (UV) spectra; phenylacetaldehyde is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; phenylacetaldehyde was not found 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.

RIFM fragrance ingredient safety assessment, hexyl hexanoate, CAS Registry Number 6378-65-0

The existing information supports the use of this material as described in this safety assessment. Hexyl hexanoate was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from read-across analog hexyl isobutyrate (CAS # 2349-07-7) show that hexyl hexanoate is not expected to be genotoxic. The repeated dose, reproductive, and local respiratory toxicity endpoints were evaluated using the threshold of toxicological concern (TTC) for a Cramer Class I material, and the exposure to hexyl hexanoate is below the TTC (0.03 mg/kg/day, 0.03 mg/kg/day, and 1.4 mg/day, respectively). 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 ultraviolet (UV) spectra; hexyl hexanoate is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; hexyl hexanoate 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.

RIFM fragrance ingredient safety assessment, tetrahydro-α-pentylfurfuryl acetate, CAS Registry Number 67634-08-6

The existing information supports the use of this material as described in this safety assessment. Tetrahydro-α-pentylfurfuryl acetate was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data show that tetrahydro-α-pentylfurfuryl acetate is not genotoxic. The repeated dose, reproductive, and local respiratory toxicity endpoints were evaluated using the threshold of toxicological concern (TTC) for a Cramer Class III material, and the exposure to tetrahydro-α-pentylfurfuryl acetate is below the TTC (0.0015 mg/kg/day, 0.0015 mg/kg/day, and 0.47 mg/day, respectively). 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 ultraviolet (UV) spectra; tetrahydro-α-pentylfurfuryl acetate is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; tetrahydro-α-pentylfurfuryl acetate 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.