Skin Sensitization Potential Research Articles

Assessment of skin sensitization potential of zinc oxide, aluminum oxide, manganese oxide, and copper oxide nanoparticles through the local lymph node assay: 5-bromo-deoxyuridine flow cytometry method

ABSTRACT The advent of nanotechnology has significantly spurred the utilization of nanoparticles (NPs) across diverse sectors encompassing industry, agriculture, engineering, cosmetics, and medicine. Metallic oxides including zinc oxide (ZnO), copper oxide (CuO), manganese oxide (Mn2O3), and aluminum oxide (Al2O3), in their NP forms, have become prevalent in cosmetics and various dermal products. Despite the expanding consideration of these compounds for dermal applications, their potential for initiating skin sensitization (SS) has not been comprehensively examined. An in vivo assay, local lymph node assay: 5-bromo-2-deoxyuridine-flow cytometry method (LLNA: BrdU-FCM) recognized as an alternative testing method for screening SS potential was used to address these issues. Following the OECD TG 442B guidelines, NPs suspensions smaller than 50 nm size were prepared for ZnO and Al2O3 at concentrations of 10, 25, and 50%, and Mn2O3 and CuO at concentrations of 5, 10, and 25%, and applied to the dorsum of each ear of female BALB/c mice on a daily basis for 3 consecutive days. Regarding the prediction of test substance to skin sensitizer if sensitization index (SI)≥2.7, all 4 NPs were classified as non-sensitizing. The SI values were below 2.06, 1.33, 1.42, and 0.99 for ZnO, Al2O3, Mn2O3, and CuO, respectively, at all test concentrations. Although data presented were negative with respect to adverse SS potential for these 4 NPs, further confirmatory tests addressing other key events associated with SS adverse outcome pathway need to be carried out to arrive at an acceptable conclusion on the skin safety for both cosmetic and dermal applications.

Deriving a point of departure for assessing the skin sensitization risk of wearable device constituents with in vitro methods

Wearable devices are in contact with the skin for extended periods. As such, the device constituents should be evaluated for their skin sensitization potential, and a Point of Departure (PoD) should be derived to conduct a proper risk assessment. Without historical in vivo data, the PoD must be derived with New Approach Methods (NAMs). To accomplish this, regression models trained on LLNA data that use data inputs from OECD-validated in vitro tests were used to derive a predicted EC3 value, the LLNA value used to classify skin sensitization potency, for three adhesive monomers (Isobornyl acrylate (IBOA), N, N- Dimethylacrylamide (NNDMA), and Acryloylmorpholine (ACMO) and one dye (Solvent Orange 60 (SO60)). These chemicals can be used as constituents of wearable devices and have been associated with causing allergic contact dermatitis (ACD). Using kinetic DPRA and KeratinoSens™ data, the PoDs obtained with the regression model were 180, 215, 1535, and 8325 μg/cm2 for IBOA, SO60, ACMO, and NNDMA, respectively. The PoDs derived with the regression model using NAMs data will enable a proper skin sensitization risk assessment without using animals.

Assessment of the feed additive consisting of Lactiplantibacillus plantarumATCC PTA-6139 for all animal species for the renewal of its authorisation (Pioneer Hi-Bred International, Inc.).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) ATCC PTA-6139 as a technological additive (functional group: silage additive) for all animal species. The applicant has provided evidence that the additive currently on the market complies with the existing conditions of authorisation. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive remains safe for all animal species, consumers and the environment. Regarding user safety, the Panel concluded that owing to the nature of the additive, Lactiplantibacillus plantarum ATCC PTA-6139 should be considered a potential skin and respiratory sensitiser, and that any exposure through the skin and respiratory tract is considered a risk. The Panel could not conclude on the eye irritation potential of the additive due to the lack of data. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.

Assessment of the feed additive consisting of Lactiplantibacillus plantarumDSM 18112 for all animal species for the renewal of its authorisation (Pioneer Hi-Bred International, Inc.).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) DSM 18112 as a technological additive (functional group: silage additive) for all animal species. The applicant has provided evidence that the additive currently on the market complies with the existing conditions of authorisation. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive remains safe for all animal species, consumers and the environment. Regarding user safety, the Panel concluded that owing to the nature of the additive, Lactiplantibacillus plantarum DSM 18112 should be considered a potential skin and respiratory sensitiser, and that any exposure through the skin and respiratory tract is considered a risk. The Panel could not conclude on the eye irritation potential of the additive due to the lack of data. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.

Assessment of the feed additive consisting of Lacticaseibacillus paracaseiATCC PTA-6135 for all animal species for the renewal of its authorisation (Pioneer Hi-Bred International, Inc.).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of authorisation of Lacticaseibacillus paracasei ATCC PTA-6135 as a technological additive (functional group: silage additive) for all animal species. The applicant has provided evidence that the additive currently on the market complies with the existing terms of the of authorisation. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the active agent L. paracasei ATCC PTA-6135 remains safe for all animal species, consumers and the environment. Regarding user safety, the panel concluded that owing to the nature of the additive, L. paracasei ATCC PTA-6135 should be considered a potential skin and respiratory sensitiser, and any exposure through the skin and respiratory tract is considered a risk. In the absence of data, no conclusion could be drawn on the eye irritation potential of the additive. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.

Assessment of the feed additive consisting of Lactiplantibacillus plantarumDSM 18113 for all animal species for the renewal of its authorisation (Pioneer Hi-Bred International, Inc.).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) DSM 18113 as a technological additive (functional group: silage additive) for all animal species. The applicant has provided evidence that the additive currently on the market complies with the existing conditions of authorisation. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive remains safe for all animal species, consumers and the environment. Regarding user safety, the Panel concluded that owing to the nature of the additive, Lactiplantibacillus plantarum DSM 18113 should be considered a potential skin and respiratory sensitiser, and that any exposure through the skin and respiratory tract is considered a risk. The Panel could not conclude on the eye irritation potential of the additive due to the lack of data. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.

Assessment of the feed additive consisting of Lactiplantibacillus plantarumDSM 18114 for all animal species for the renewal of its authorisation (Pioneer Hi-Bred International, Inc.).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) DSM 18114 as a technological additive (functional group: silage additive) for all animal species. The applicant has provided evidence that the additive currently on the market complies with the existing conditions of authorisation. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive remains safe for all animal species, consumer and the environment. Regarding user safety, the Panel concluded that owing to the nature of the additive, Lactiplantibacillus plantarum DSM 18114 should be considered a potential skin and respiratory sensitiser, and that any exposure through the skin and respiratory tract is considered a risk. The Panel could not conclude on the eye irritation potential of the additive due to the lack of data. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.

Assessment of the feed additive consisting of Lactiplantibacillus plantarumATCC 55944 for all animal species for the renewal of its authorisation (Pioneer Hi-Bred International, Inc.).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) ATCC 55944 as a technological additive (functional group: silage additive) for all animal species. The applicant has provided evidence that the additive currently on the market complies with the existing conditions of authorisation. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive remains safe for all animal species, consumer and the environment. Regarding user safety, the Panel concluded that owing to the nature of the additive, Lactiplantibacillus plantarum ATCC 55944 should be considered a potential skin and respiratory sensitiser, and that any exposure through the skin and respiratory tract is considered a risk. The Panel could not conclude on the eye irritation potential of the additive due to the lack of data. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.

Assessment of the feed additive consisting of Lactiplantibacillus plantarumATCC 55943 for all animal species for the renewal of its authorisation (Pioneer Hi-Bred International, Inc.).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) ATCC 55943 as a technological additive (functional group: silage additive) for all animal species. The applicant has provided evidence that the additive currently on the market complies with the existing conditions of authorisation. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive remains safe for all animal species, consumers and the environment. Regarding user safety, the Panel concluded that owing to the nature of the additive, Lactiplantibacillus plantarum ATCC 55943 should be considered a potential skin and respiratory sensitiser, and any exposure through the skin and respiratory tract is considered a risk. The Panel could not conclude on the eye irritation potential of the additive due to the lack of data. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.

A Human Skin Explant Test as a Novel In Vitro Assay for the Detection of Skin Sensitization to Aggregated Monoclonal Antibodies.

Introduction: Monoclonal antibodies (mAbs) are important therapeutics. However, the enhanced potential for aggregation has become a critical quality parameter during the production of mAbs. Furthermore, mAb aggregation may also present a potential health risk in a clinical setting during the administration of mAb therapeutics to patients. While the extent of immunotoxicity in patient populations is uncertain, reports show it can lead to immune responses via cell activation and cytokine release. In this study, an autologous in vitro skin test designed to predict adverse immune events, including skin sensitization, was used as a novel assay for the assessment of immunotoxicity caused by mAb aggregation. Material and Methods: Aggregation of mAbs was induced by a heat stress protocol, followed by characterization of protein content by analytical ultra-centrifugation and transmission electron microscopy, revealing a 4% aggregation level of total protein content. Immunotoxicity and potential skin sensitization caused by the aggregates, were then tested in a skin explant assay. Results: Aggregated Herceptin and Rituximab caused skin sensitization, as shown by histopathological damage (grade II-III positive response) together with positive staining for Heat Shock Protein 70 (HSP70). Changes in T cell proliferation were not observed. Cytokine analysis revealed a significant increase of IL-10 for the most extreme condition of aggregation (65 °C at pH3) and a trend for an overall increase of IFN-γ, especially in response to Rituximab. Conclusions: The skin explant assay demonstrated that aggregated mAbs showed adverse immune reactions, as demonstrated as skin sensitization, with histopathological grades II-III. The assay may, therefore, be a novel tool for assessing immunotoxicity and skin sensitization caused by mAb aggregation.

Assessment of the feed additive consisting of Saccharomyces cerevisiaeMUCL 39885 (Biosprint®) for cattle for fattening for the renewal of its authorisation (Prosol SPA).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of the authorisation of Saccharomyces cerevisiae MUCL 39885 (Biosprint®) as a feed additive for cattle for fattening (category: zootechnical; functional group: gut flora stabiliser). The applicant provided evidence that the additive currently in the market complies with the conditions of authorisation. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) confirmed that the use of Biosprint® under the current authorised conditions of use remains safe for the target species, the consumers and the environment. Taking into account the nature of the additive, the FEEDAP Panel concludes that the additive should be considered as a potential skin and respiratory sensitiser, and any exposure through skin and respiratory tract is considered a risk. The additive is not a skin/eye irritant. There is no need to assess the efficacy of Biosprint® in the context of the renewal of the authorisation.

Evaluation of the applicability of GARDskin to predict skin sensitizers in extracts from medical device materials.

Biocompatibility testing of medical devices is governed by the ISO 10993 series of standards and includes evaluation of skin sensitization potential of the final product. A majority of all medical devices are tested using in vivo methods, largely due to the lack of in vitro methods validated within the applicability domain of solid materials. The GARDskin method for assessment of chemical skin sensitizers is a validated method included in the OECD Test Guideline 442E, based on evaluation of transcriptional patterns of an endpoint-specific genomic biomarker signature in a dendritic cell-like cell, following test chemical exposure. The current study aimed to evaluate the applicability of GARDskin for the purpose of testing solid materials by incorporation of extraction procedures described in ISO 10993-12:2021, as well as to demonstrate the functionality of the proposed protocols, by testing of custom-made materials spiked with sensitizing agents. It was shown that GARDskin is compatible with both polar and non-polar extraction vehicles frequently used for the purpose of medical device biological testing. Further, exploring three different material types spiked with up to four different sensitizing agents, as well as three unspiked control materials and commercial reference products, it was shown that the method correctly classified all evaluated test materials. Taken together, the data presented suggest that GARDskin may constitute a valid alternative to in vivo experimentation for the purpose of skin sensitization assessment of medical devices.

Assessment of the feed additive consisting of Bacillus velezensisATCC PTA-6737 (PB6) for turkeys for fattening and turkeys reared for breeding for the renewal of its authorisation and the modification of the conditions of the authorisation for other growing poultry species (Kemin Europe N.V).

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on Bacillus velezensis ATCC PTA-6737 as a zootechnical additive (functional group: gut-flora stabiliser) in the context of the renewal of the authorisation for turkeys for fattening and turkeys reared for breeding. The applicant is also requesting to modify the target species in the current authorisations to 'all growing poultry', the increase of the recommended use level in chickens for fattening, chickens reared for laying and minor poultry species except minor poultry for laying from 1 × 107 to 1 × 108 CFU/kg complete feed and the compatibility of the additive with halofuginone. The applicant provided evidence that the additive currently in the market complies with the conditions of the authorisation. There was no new evidence that would lead to reconsider previous conclusions. Therefore, the FEEDAP Panel concluded that the additive remains safe for all poultry species for fattening and reared for laying/breeding, the consumers and the environment under the current authorised conditions of use. The additive is not irritant to the skin and eyes, but it should be considered a respiratory sensitiser. The Panel could not conclude on the skin sensitisation potential of the additive. The Panel concluded that the additive has a potential to be efficacious as a zootechnical additive for poultry for fattening and reared for laying/breeding under the proposed conditions of use.

Use of in vitro methods combined with in silico analysis to identify potential skin sensitizers in the Tox21 10K compound library.

Introduction: Skin sensitization, which leads to allergic contact dermatitis, is a key toxicological endpoint with high occupational and consumer prevalence. This study optimized several in vitro assays listed in OECD skin sensitization test guidelines for use on a quantitative high-throughput screening (qHTS) platform and performed in silico model predictions to assess the skin sensitization potential of prioritized compounds from the Tox21 10K compound library. Methods: First, we screened the entire Tox21 10K compound library using a qHTS KeratinoSensTM (KS) assay and built a quantitative structure-activity relationship (QSAR) model based on the KS results. From the qHTS KS screening results, we prioritized 288 compounds to cover a wide range of structural chemotypes and tested them in the solid phase extraction-tandem mass spectrometry (SPE-MS/MS) direct peptide reactivity assay (DPRA), IL-8 homogeneous time-resolved fluorescence (HTRF) assay, CD86 and CD54 surface expression in THP1 cells, and predicted in silico sensitization potential using the OECD QSAR Toolbox (v4.5). Results: Interpreting tiered qHTS datasets using a defined approach showed the effectiveness and efficiency of in vitro methods. We selected structural chemotypes to present this diverse chemical collection and to explore previously unidentified structural contributions to sensitization potential. Discussion: Here, we provide a skin sensitization dataset of unprecedented size, along with associated tools, and analysis designed to support chemical assessments.

Assessment of the feed additive consisting of Pediococcus pentosaceusDSM 23689 for all animal species for the renewal of its authorisation (Chr. Hansen A/S).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of the authorisation of Pediococcus pentosaceus DSM 23689 as a technological additive, silage additive for all animal species. The applicant has provided evidence that the additive currently on the market complies with the existing conditions of authorisation. The Panel concluded that the additive remains safe for all animal species, consumers, and the environment under the authorised conditions of use. Regarding user safety, the additive should be considered as a respiratory sensitiser. No conclusions can be drawn on the skin sensitisation, and skin and eye irritancy potential of the additive. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.

Safety and efficacy of a feed additive consisting of Bacillus velezensisATCC PTA-6737 (PB6) for the renewal of the authorisations in weaned piglets, weaned minor porcine species and sows and the extension of use to all Suidae (Kemin Europe N.V).

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on Bacillus velezensis ATCC PTA-6737 as a zootechnical additive (functional group: gut flora stabilisers) in regard to the renewal of the authorisation for weaned piglets, weaned minor porcine species, sows and minor reproductive Suidae species, and its extension of use for all Suidae. The applicant provided evidence that the additive currently in the market complies with the conditions of the authorisation. The Panel concluded that there is no new evidence that would lead it to reconsider the previous conclusions; the additive is safe for the target species, consumers and the environment under the authorised conditions of use. This conclusion also applies to the target species/categories for which a request for an extension of use is made. The Panel concluded that B. velezensis ATCC PTA-6737 is not irritant to skin or eyes but should be considered a respiratory sensitiser due to its proteinaceous nature. No conclusions could be drawn on the skin sensitisation potential of the additive. The Panel concluded that the additive has the potential to be efficacious in all growing Suidae (suckling, weaned and fattening Suidae) at the minimum inclusion level of 1 × 107 CFU/kg of complete feed and in sows and minor reproductive Suidae species at 1 × 108 CFU/kg complete feed.

Assessment of the feed additive consisting of Pediococcus pentosaceusDSM 23688 for all animal species for the renewal of its authorisation (Chr. Hansen A/S).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of Pediococcus pentosaceus DSM 23688, a technological additive for all animal species. The applicant has provided evidence that the additive currently on the market complies with the existing conditions of authorisation. The Panel concluded that the additive remains safe for all animal species, consumers, and the environment under the authorised conditions of use. Regarding user safety, the additive was shown not to be irritant to skin or eyes. The Panel was not in the position to conclude on skin sensitisation potential of the additive, but it is considered to be a respiratory sensitiser. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.

Computational application of internationally harmonized defined approaches to skin sensitization: DASS App.

Chemically induced skin sensitization, or allergic contact dermatitis, is a common occupational and public health issue. Regulatory authorities require an assessment of potential to cause skin sensitization for many chemical products. Defined approaches for skin sensitization (DASS) identify potential chemical skin sensitizers by integrating data from multiple non-animal tests based on human cells, molecular targets, and computational model predictions using standardized data interpretation procedures. While several DASS are internationally accepted by regulatory agencies, the data interpretation procedures vary in logical complexity, and manual application can be time-consuming or prone to error. We developed the DASS App, an open-source web application, to facilitate user application of three regulatory testing strategies for skin sensitization assessment: the Two-out-of-Three (2o3), the Integrated Testing Strategy (ITS), and the Key Event 3/1 Sequential Testing Strategy (KE 3/1 STS) without the need for software downloads or computational expertise. The application supports upload and analysis of user-provided data, includes steps to identify inconsistencies and formatting issues, and provides predictions in a downloadable format. This open-access web-based implementation of internationally harmonized regulatory guidelines for an important public health endpoint is designed to support broad user uptake and consistent, reproducible application. The DASS App is freely accessible via https://ntp.niehs.nih.gov/go/952311 and all scripts are available on GitHub ( https://github.com/NIEHS/DASS ).

Assessment of the feed additive consisting of Lentilactobacillus buchneri (formerly Lactobacillus buchneri) DSM 22501 for all animal species for the renewal of its authorisation (Chr. Hansen A/S).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for renewal of the authorisation of the additive consisting of Lentilactobacillus buchneri DSM 22501 as a technological feed additive to improve ensiling of fresh material for all animal species. The applicant has provided evidence that the additive currently on the market complies with the existing conditions of authorisation. There is no new evidence that would lead the FEEDAP Panel to reconsider its previous conclusions. Thus, the Panel concludes that the additive remains safe for all animal species, consumer and the environment under the authorised conditions of use. Regarding user safety, the additive is not irritant to skin and eye, but owing to its proteinaceous nature it should be considered a respiratory sensitiser. No conclusions could be drawn on the skin sensitisation potential of the additive. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.

Utilizing integrated testing strategy (ITSv1) defined approach and read across to predict skin sensitization of cannabidiol

Cannabidiol (CBD) is increasingly being used as an ingredient in cosmetics, but to date no pre-clinical studies have been published to address the skin sensitization end point. This case study investigated its skin sensitization potential for use in a face cream application at 0.3 % using Next Generation Risk Assessment (NGRA) framework. Based on chemical structure and in-silico prediction using Derek Nexus, CBD was predicted to be weak sensitizer with a resorcinol alert moiety. In vitro testing was conducted confirming it to be sensitizer, but the New Approach Methodologies (NAM) data could not provide sufficient confidence to determine a point of departure (PoD). Integrated testing strategy (ITS)v1 Defined Approach (DA), adopted in OECD Guideline No. 497, was used for skin sensitization potency categorization. However, ITSv1 DA alone is not used for further refinement of the potency prediction based on EC3 (the estimated concentration that produces a stimulation index of 3 in murine local lymph node assay) values. Therefore, the application of read-across using Derek Nexus derived a PoD derived from the LLNA EC3 of 42 %. This led to a favorable NGRA conclusion and to support use of CBD at 0.3 % in face cream application.