L. Nardelli

Multi-laboratory validation of SkinEthic HCE test method for testing serious eye damage/eye irritation using liquid chemicals.

A prospective multicentric study of the reconstructed human corneal epithelial tissue-based in vitro test method (SkinEthic™ HCE) was conducted to evaluate its usefulness to identify chemicals as either not classified for serious eye damage/eye irritation (No Cat.) or as classified (Cat. 1/Cat. 2) within UN GHS. The aim of this study was to demonstrate the transferability and reproducibility of the SkinEthic™ HCE EITL protocol for liquids and define its predictive capacity. Briefly, 60 chemicals were three times tested (double blinded) in 3 laboratories and 45 additional chemicals were tested three times in one laboratory. Good within laboratory reproducibility was achieved of at least 88.3% (53/60) and 92.4% (97/105) for the extended data set. Furthermore, the overall concordance between the laboratories was 93.3% (56/60). The accuracy of the SkinEthic™ HCE EITL for the extended dataset, based on bootstrap resampling, was 84.4% (95% CI: 81.9% to 87.6%) with a sensitivity of 99.0% (95% CI: 96.4% to 100%) and specificity of 68.5% (95% CI: 64.0% to 74.0%), thereby meeting all acceptance criteria for predictive capacity. This efficient transferable and reproducible assay is a promising tool to be integrated within a battery of assays to perform an eye irritation risk assessment.

Multi-laboratory evaluation of SkinEthic HCE test method for testing serious eye damage/eye irritation using solid chemicals and overall performance of the test method with regard to solid and liquid chemicals testing

A prospective multicentre study of the reconstructed human corneal epithelial tissue-based in vitro test method (SkinEthic™ HCE) was conducted to evaluate its usefulness to identify chemicals as either not classified for serious eye damage/eye irritation (No Cat.) or as classified (Cat. 1/Cat. 2) within UN GHS. The aim of this study was to demonstrate the transferability and reproducibility of the SkinEthic™ HCE EITS protocol for solids and define its predictive capacity. Briefly, 60 chemicals were three times tested (double blinded) in 3 laboratories and 35 additional chemicals were tested three times in one laboratory. Good within laboratory reproducibility was achieved of at least 95% (57/60) and 96.8% (92/95) for the extended data set. Furthermore, the overall concordance between the laboratories was 96.7% (58/60). The accuracy of the SkinEthic™ HCE EITS for the extended dataset, based on bootstrap resampling, was 81.0% (95% CI: 78.9% to 83.2%) with a sensitivity of 90.5% (95% CI: 88.1% to 92.9%) and specificity of 73.6% (95% CI: 71.7% to 75.5%). Overall, 200 chemicals were tested (105 liquids (EITL protocol) and 95 solids (EITS protocol)) resulting in a sensitivity of 95.2%, specificity of 72.1% and accuracy of 83.7%, thereby meeting all acceptance criteria for predictive capacity.

CON4EI: SkinEthic™ Human Corneal Epithelium Eye Irritation Test (SkinEthic™ HCE EIT) for hazard identification and labelling of eye irritating chemicals

Assessment of ocular irritancy is an international regulatory requirement and a necessary step in the safety evaluation of industrial and consumer products. Although a number of in vitro ocular irritation assays exist, none are capable of fully categorizing chemicals as a stand-alone assay. Therefore, the CEFIC-LRI-AIMT6-VITO CON4EI (CONsortium for in vitro Eye Irritation testing strategy) project was developed with the goal of assessing the reliability of eight in vitro/alternative test methods as well as establishing an optimal tiered-testing strategy. One of the in vitro assays selected was the validated SkinEthic™ Human Corneal Epithelium Eye Irritation Test method (SkinEthic™ HCE EIT). The SkinEthic™ HCE EIT has already demonstrated its capacity to correctly identify chemicals (both substances and mixtures) not requiring classification and labelling for eye irritation or serious eye damage (No Category). The goal of this study was to evaluate the performance of the SkinEthic™ HCE EIT test method in terms of the important in vivo drivers of classification. For the performance with respect to the drivers all in vivo Cat 1 and No Cat chemicals were 100% correctly identified. For Cat 2 chemicals the liquids and the solids had a sensitivity of 100% and 85.7%, respectively. For the SkinEthic™ HCE EIT test method, 100% concordance in predictions (No Cat versus No prediction can be made) between the two participating laboratories was obtained. The accuracy of the SkinEthic™ HCE EIT was 97.5% with 100% sensitivity and 96.9% specificity. The SkinEthic™ HCE EIT confirms its excellent results of the validation studies.

U-SENS™: A U937 Cell Line Activation Test for Skin Sensitization

The U-SENS™ assay is modelling the dendritic cell activation upon exposure to chemicals. Upon contact with sensitizers, U937 human histiocytic lymphoma cells are activated and increase the CD86 expression. The U-SENS™ assay addressing one biological mechanism of the skin sensitization pathway (formally described in an Adverse Outcome Pathway (AOP) for skin sensitization by the OECD) is foreseen to be combined with complementary information and evaluated in the context of Integrated Approaches to Testing and Assessment (IATA). In such context, the U-SENS™ assay is part of a decision strategy for skin sensitization hazard identification (contact skin sensitizer vs. non-sensitizer). It is also foreseen to be a part of integrated test batteries which will be able to fully replace the in vivo test methods (i.e. Local Lymph Node Assay-LLNA, Buehler and Magnusson & Kligman) to predict the sensitizing potential of the chemicals in humans (risk and safety assessment). The reproducibility and predictivity of the U-SENS™ assay were evaluated by two multicentric validation studies organized with four laboratories, and with a large set of 175 chemicals through a systematic in vitro and human and/or LLNA comparative evaluation for skin sensitization safety assessment. The U-SENS™ assay was shown to be robust, transferable and automatable, delivering results that matched well with corresponding human/LLNA sensitization data. On the basis of the data currently available, the U-SENS™ method was shown to be applicable to test chemicals (including cosmetics ingredients) covering a variety of organic functional groups, physicochemical properties and skin sensitization potencies (as determined in in vivo studies). The U-SENS™ assay is applicable to all mono-substances or mixtures (including pre- or pro-haptens) that are soluble in the aqueous testing conditions and compatible with flow cytometry analysis.