No Expected Sensitization Induction Level Research Articles

GARDskin dose-response assay and its application in conducting Quantitative Risk Assessment (QRA) for fragrance materials using a Next Generation Risk Assessment (NGRA) framework

Development of New Approach Methodologies (NAMs) capable of providing a No Expected Sensitization Induction Level (NESIL) value remains a high priority for the fragrance industry for conducting a Quantitative Risk Assesment (QRA) to evaluate dermal sensitization. The in vitro GARDskin assay was recently adopted by the OECD (TG 442E) for the hazard identification of skin sensitizers. Continuous potency predictions are derived using a modified protocol that incorporates dose-response measurements. Linear regression models have been developed to predict human NESIL values. The aim of the study was to evaluate the precision and reproducibility of the continuous potency predictions from the GARDskin Dose-Response (DR) assay and its application in conducting QRA for fragrance materials using a Next Generation Risk Assessment (NGRA) framework. Results indicated that the GARDskin Dose-Response model predicted human NESIL values with a good degree of concordance with published NESIL values, which were also reproducible in 3 separate experiments. Using Isocyclocitral as an example, a QRA was conducted to determine its safe use levels in different consumer product types using a NGRA framework. This study represents a major step towards the establishment of the assay to derive NESIL values for conducting QRA evaluations for fragrance materials using a NGRA framework.

Assessing the risk of induction of skin sensitization to plant protection products: A quantitative approach

Exposure to skin sensitizers is common and regulated in many industry sectors. For cosmetics, a risk-based approach has been implemented, focused on preventing the induction of sensitization. First, a No Expected Sensitization Induction Level (NESIL) is derived, then modified by Sensitization Assessment Factors (SAFs) to derive an Acceptable Exposure Level (AEL). The AEL is used in risk assessment, being compared with an estimated exposure dose, specific to the exposure scenario. Since in Europe there is increased concern regarding exposure towards potentially sensitizing pesticides via spray drift, we explore how existing practice can be modified to allow Quantitative Risk Assessment (QRA) of pesticides for bystanders and residents. NESIL derivation by the Local Lymph Node Assay (LLNA), the globally required in vivo assay for this endpoint, is reviewed alongside consideration of appropriate SAFs. Using a case study, the principle that the NESIL in μg/cm2 can be derived by multiplying LLNA EC3% figure by a factor of 250 is adopted. The NESIL is then reduced by an overall SAF of 25 to establish an exposure level below which there is minimal bystander and resident risk. Whilst this paper focuses on European risk assessment and management, the approach is generic and universally applicable.

RIFM fragrance ingredient safety assessment, geraniol, CAS registry number 106-24-1.

The existing information supports the use of this material as described in this safety assessment. Geraniol was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data show that geraniol is not genotoxic. Data on geraniol provide a calculated Margin of Exposure (MOE)>100 for the repeated dose toxicity and reproductive toxicity endpoints. Data provided geraniol a No Expected Sensitization Induction Level (NESIL) of 11000μg/cm2 for the skin sensitization endpoint. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet/visible (UV/Vis) spectra; geraniol 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 geraniol is below the TTC (1.4mg/day). The environmental endpoints were evaluated; geraniol 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-Cyclohexene-1-carboxaldehyde, 1-ethenyl-, CAS Registry Number 1049017-63-1.

The existing information supports the use of this material as described in this safety assessment. 3-Cyclohexene-1-carboxaldehyde, 1-ethenyl- was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data show that 3-cyclohexene-1-carboxaldehyde, 1-ethenyl- is not genotoxic. Data on 3-cyclohexene-1-carboxaldehyde, 1-ethenyl- provide a calculated Margin of Exposure (MOE)>100 for the repeated dose toxicity endpoint. The 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 3-cyclohexene-1-carboxaldehyde, 1-ethenyl-is below the TTC (0.03mg/kg/day and 1.4mg/day, respectively). Data provided 3-cyclohexene-1-carboxaldehyde, 1-ethenyl- a No Expected Sensitization Induction Level (NESIL) of 1000μg/cm2 for the skin sensitization endpoint. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet/visible (UV/Vis) spectra; 3-cyclohexene-1-carboxaldehyde, 1-ethenyl- is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; 3-cyclohexene-1-carboxaldehyde, 1-ethenyl- 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, l-carvone, CAS Registry Number 6485-40-1

l-Carvone was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data show that l-carvone is not genotoxic and provided a No Expected Sensitization Induction Level (NESIL) of 2600 μg/cm2 for the skin sensitization endpoint. Data on l-carvone provided a calculated Margin of Exposure (MOE) >100 for the repeated dose toxicity and reproductive toxicity endpoints. The phototoxicity/photoallergenicity endpoint was completed based on data and ultraviolet/visible (UV/Vis) spectra; l-carvone is not phototoxic/photoallergenic. The local respiratory toxicity endpoint was evaluated using the Threshold of Toxicological Concern (TTC) for a Cramer Class II material (0.47 mg/day); the exposure to l-carvone is below the TTC. The environmental endpoints were evaluated; l-carvone 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, octyl isobutyrate, CAS Registry Number 109-15-9

The existing information supports the use of this material as described in this safety assessment. Octyl isobutyrate 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 octyl isobutyrate is not expected to be genotoxic. Data on analog propyl (2S)-2-(1,1-dimethylpropoxy)-propanoate (CAS # 319002-92-1) provide a calculated Margin of Exposure (MOE) > 100 for the repeated dose and reproductive toxicity endpoints. Data from analog hexyl 2-methylbutyrate (CAS # 10032-15-2) provided octyl isobutyrate a No Expected Sensitization Induction Level (NESIL) of 7000 μg/cm2 for the skin sensitization endpoint. Octyl isobutyrate is not expected to be phototoxic/photoallergenic based on ultraviolet/visible (UV/Vis) spectra. The local respiratory toxicity endpoint was evaluated using the Threshold of Toxicological Concern (TTC) for a Cramer Class I material; exposure to is below the TTC (1.4 mg/day). The environmental endpoints were evaluated; octyl isobutyrate 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, 4-(2,6,6-trimethyl-2-cyclohexen)-2-methylbutanal, CAS Registry Number 65405-84-7

The existing information supports the use of this material as described in this safety assessment. 4-(2,6,6-Trimethyl-2-cyclohexen)-2-methylbutanal was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data show that 4-(2,6,6-trimethyl-2-cyclohexen)-2-methylbutanal 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 I material, and the exposure to 4-(2,6,6-trimethyl-2-cyclohexen)-2-methylbutanal is below the TTC (0.03 mg/kg/day, 0.03 mg/kg/day, and 1.4 mg/day, respectively). Data provided 4-(2,6,6-trimethyl-2-cyclohexen)-2-methylbutanal a No Expected Sensitization Induction Level (NESIL) of 1100 μg/cm2 for the skin sensitization endpoint. The phototoxicity/photoallergenicity endpoints were evaluated based on data and ultraviolet/visible (UV/Vis) spectra; 4-(2,6,6-trimethyl-2-cyclohexen)-2-methylbutanal is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; 4-(2,6,6-trimethyl-2-cyclohexen)-2-methylbutanal 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, cis-3-hexenyl tiglate, CAS Registry Number 67883-79-8

The existing information supports the use of this material as described in this safety assessment. cis-3-Hexenyl tiglate was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from read-across analogs 2-methyl-trans-2-butenoic acid (CAS # 80-59-1) and cis-3-hexenol (CAS # 928-96-1) show that cis-3-hexenyl tiglate is not expected to be genotoxic. The repeated dose, reproductive, and local respiratory toxicity endpoints were evaluated using the Threshold for Toxicological Concern (TTC) for a Cramer Class I material; exposure to cis-3-hexenyl tiglate is below the TTC (0.03 mg/kg/day, 0.03 mg/kg/day and 1.4 mg/day, respectively). Data from analog 2-hexenoic acid, 2-methyl-, methyl ester, (2E)- (CAS # 16493-96-2) provided cis-3-hexenyl tiglate a No Expected Sensitization Induction Level (NESIL) of 1100 μg/cm2 for the skin sensitization endpoint. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet/visible (UV/Vis) spectra; cis-3-hexenyl tiglate is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; cis-3-hexenyl tiglate 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, 4,8-decadienal, (4Z,8Z)-, CAS Registry Number 1958027-35-4

Summary: The existing information supports the use of this material as described in this safety assessment.4,8-Decadienal, (4Z,8Z)- was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from read-across analogs 4,7-decadienal (CAS # 934534-30-2) and nona-2-trans-6-cis-dienal (CAS # 557-48-2) show that 4,8-decadienal, (4Z,8Z)- is not expected to be genotoxic. Data on analog 10-undecenal (CAS # 112-45-8) provide a calculated Margin of Exposure (MOE) > 100 for the repeated dose toxicity and fertility endpoints and a No Expected Sensitization Induction Level (NESIL) of 1700 μg/cm2 for the skin sensitization endpoint. The developmental toxicity and local respiratory toxicity endpoints were evaluated using the Threshold of Toxicological Concern (TTC) for Cramer Class I materials; exposure is below the TTC (0.03 mg/kg/day and 1.4 mg/day, respectively). The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet/visible (UV/Vis) spectra; 4,8-decadienal, (4Z,8Z)- is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; 4,8-decadienal, (4Z,8Z)- was found not to be Persistent, Bioaccumulative, and Toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards. 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, 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.

RIFM fragrance ingredient safety assessment, 4-ethylbenzaldehyde, CAS Registry Number 4748-78-1

The existing informationsupportsthe use of this material as described in this safety assessment. 4-ethylbenzaldehyde was evaluated for genotoxicity, repeated dose toxicity, developmental and reproductive toxicity, local respiratory toxicity, phototoxicity, skin sensitization, and environmental safety. Data on the read-across analog benzaldehyde (CAS # 100-52-7) show that 4-ethylbenzaldehyde is not expected to be genotoxic and provide a calculated margin of exposure (MOE) >100 for the repeated dose toxicity endpoint. Data on read-across analog 3,4-dimethylbenzaldehyde (CAS # 5973-71-7) provide a calculated MOE >100 for the developmental and reproductive toxicity endpoints. Data on read-across analog cuminaldehyde (CAS # 122-03-2) provided 4-ethylbenzaldehyde a No Expected Sensitization Induction Level (NESIL) of 1100 μg/cm². The local respiratory toxicity endpoint was evaluated using the threshold of toxicological concern (TTC) for a Cramer Class I material; exposure is below the TTC (1.4 mg/day). The phototoxicity/photoallergenicity endpoints were evaluated based on data; 4-ethylbenzaldehyde is not phototoxic/photoallergenic. The environmental endpoints were evaluated; 4-ethylbenzaldehyde 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, 2-phenylpropionaldehyde, CAS Registry Number 93-53-8

Summary: 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

Summary: 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, 3-(m-tert-butylphenyl)-2-methylpropionaldehyde, CAS Registry Number 62518-65-4

The existing information supports the use of 3-(m-tert-butylphenyl)-2-methylpropionaldehyde as described in this safety assessment. 3-(m-tert-Butylphenyl)-2-methylpropionaldehyde 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 p-t-butyl-α-methylhydrocinnamic aldehyde (CAS # 80-54-6) show that 3-(m-tert-butylphenyl)-2-methylpropionaldehyde is not expected to be genotoxic. Data on 3-(m-tert-butylphenyl)-2-methylpropionaldehyde provide a calculated margin of exposure (MOE) >100 for the repeated dose toxicity and developmental and reproductive toxicity endpoints. Data from read-across analog p-t-butyl-α-methylhydrocinnamic aldehyde (CAS # 80-54-6) provided 3-(m-tert-butylphenyl)-2-methylpropionaldehyde a No Expected Sensitization Induction Level (NESIL) of 4100 μg/cm2 for the skin sensitization endpoint. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet (UV) spectra; 3-(m-tert-butylphenyl)-2-methylpropionaldehyde 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; the exposure to 3-(m-tert-butylphenyl)-2-methylpropionaldehyde is below the TTC (1.4 mg/day). The environmental endpoints were evaluated; 3-(m-tert-butylphenyl)-2-methylpropionaldehyde 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, cinnamyl alcohol, CAS Registry Number 104-54-1

The existing information supports the use of this material as described in this safety assessment. Cinnamyl alcohol was evaluated for genotoxicity, repeated dose toxicity, developmental toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity, skin sensitization, and environmental safety. Data show that cinnamyl alcohol is not genotoxic. Data on read-across analog cinnamaldehyde (CAS # 104-55-2) provide a calculated margin of exposure (MOE) >100 for the repeated dose and local respiratory toxicity endpoints. The developmental and reproductive toxicity endpoint was evaluated using the threshold of toxicological concern (TTC) for a Cramer Class I material, and the exposure to cinnamyl alcohol is below the TTC (0.03 mg/kg/day). Data provided a No Expected Sensitization Induction Level (NESIL) of 2900 μg/cm2 for the skin sensitization endpoint. The phototoxicity/photoallergenicity endpoints were evaluated based on UV spectra; cinnamyl alcohol is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; cinnamyl alcohol 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.

Adjustment of a no expected sensitization induction level derived from Bayesian network integrated testing strategy for skin sensitization risk assessment.

Skin sensitization is a key adverse effect to be addressed during hazard identification and risk assessment of chemicals, because it is the first step in the development of allergic contact dermatitis. Multiple non-animal testing strategies incorporating in vitro tests and in silico tools have achieved good predictivities when compared with murine local lymph node assay (LLNA). The binary test battery of KeratinoSensTM and h-CLAT could be used to classify non-sensitizers as the first part of bottom-up approach. However, the quantitative risk assessment for sensitizing chemicals requires a No Expected Sensitization Induction Level (NESIL), the dose not expected to induce skin sensitization in humans. We used Bayesian network integrated testing strategy (BN ITS-3) for chemical potency classification. BN ITS-3 predictions were performed without a pre-processing step (selecting data from their physic-chemical applicability domains) or post-processing step (Michael acceptor chemistry correction), neither of which necessarily improve prediction accuracy. For chemicals within newly defined applicability domain, all under-predictions fell within one potency class when compared with LLNA results, indicating no chemicals that were incorrectly classified by more than one class. Considering the potential under-prediction by one class, a worst case value to each class from BN ITS-3 was used to derive a NESIL. When in vivo and human data from suitable analogs cannot be used to estimate the uncertainty, adjusting the NESIL derived from BN ITS-3 may help perform skin sensitization risk assessment. The overall workflow for risk assessment was demonstrated by incorporating the binary test battery of KeratinoSensTM and h-CLAT.

Deriving a No Expected Sensitization Induction Level for Fragrance Ingredients Without Animal Testing: An Integrated Approach Applied to Specific Case Studies

Cosmetic regulations prohibit animal testing for the purpose of safety assessment and recent registration, evaluation and authorization of chemicals guidance states that the local lymph node assay (LLNA) in mice shall only be conducted if in vitro data cannot give sufficient information for classification and labeling. However, Quantitative Risk Assessment for fragrance ingredients requires an NESIL (no expected sensitization induction level), a dose not expected to cause induction of skin sensitization in humans. In absence of human data, this is derived from the LLNA and it remains a key challenge for risk assessors to derive this value from nonanimal data. Here we present a workflow using structural information, reactivity data and KeratinoSens results to predict an LLNA result as a point of departure. Specific additional tests (metabolic activation, complementary reactivity tests) are applied in selected cases depending on the chemical domain of a molecule. Finally, in vitro and in vivo data on close analogues are used to estimate uncertainty of the prediction in the specific chemical domain. This approach was applied to three molecules which were subsequently tested in the LLNA and 22 molecules with available and sometimes discordant human and LLNA data. Four additional case studies illustrate how this approach is being applied to recently developed molecules in the absence of animal data. Estimation of uncertainty and how this can be applied to determine a final NESIL for risk assessment is discussed. We conclude that, in the data-rich domain of fragrance ingredients, sensitization risk assessment without animal testing is possible in most cases by this integrated approach.

Probabilistic derivation of the interspecies assessment factor for skin sensitization

An interspecies sensitization assessment factor (SAF) is used in the quantitative risk assessment (QRA) for skin sensitization when a murine-based NESIL (No Expected Sensitization Induction Level) is taken as point of departure. Several studies showed that, on average, the murine sensitization threshold is in good correspondence with that determined in humans. However, on an individual level, the murine and human sensitization thresholds may differ considerably. In this study, the interspecies SAF was quantified by using a probabilistic approach, to be able to take these cases into account. As expected, the geometric means of the probability distributions of murine and human sensitization threshold ratios were close to one, but taking the 95 th percentile of these distributions resulted in an interspecies SAF of 15. By using this value, one is sure that with 95% probability, the sensitization threshold determined in mice does not underestimate the human threshold. It can be concluded that a murine-based NESIL requires the use of an interspecies SAF (of 15) in the QRA for skin sensitization, to correct for the differences between mice and humans. This empirically derived interspecies SAF contributes to refinement of the risk assessment methodology.

Risk Assessment of residual monomer migrating from acrylic polymers and causing Allergic Contact Dermatitis during normal handling and use

Acrylic, Poly Methyl Methacrylate (PMMA) based polymers are found in many industrial, professional and consumer products and are of low toxicity, but do contain very low levels of residual monomers and process chemicals that can leach out during handling and use. Methyl Methacrylate, the principle monomer is of low toxicity, but is a recognized weak skin sensitizer. The risk of induction of contact allergy in consumers was determined using a method based upon the Exposure-based Quantitative Risk Assessment approach developed for fragrance ingredients. The No Expected Sensitization Induction Level (NESIL) was based on the threshold to induction of sensitization (EC3) in the Local Lymph Node Assay (LLNA) since no Human Repeat Insult Patch Test (HRIPT) data were available. Categorical estimation of Consumer Exposure Level was substituted with a worst case assumption based upon the quantitative determination of MMA monomer migration into simulants. Application of default and Chemical-Specific Adjustment Factors results in a Risk Characterization Ratio (RCR) of 10,000 and a high Margin of Safety for induction of Allergic Contact Dermatitis (ACD) in consumers handling polymers under conservative exposure conditions. Although there are no data available to derive a RCR for elicitation of ACD it is likely to be lower than that for induction.