A feasibility study developing an integrated testing strategy assessing skin irritation potential of chemicals.

European Centre for the Validation of Alternative Methods (ECVAM), Institute of Health and Consumer Protection (IHCP), Joint Research Centre, European Commission, Via E.Fermi 2749, 21027 Ispra (VA), Italy.
Toxicology Letters (Impact Factor: 3.15). 08/2008; 180(1):9-20. DOI: 10.1016/j.toxlet.2008.05.004
Source: PubMed

ABSTRACT The regulatory assessment of chemical safety is still driven by hazard testing in animals. The Registration, Evaluation, Authorisation and restriction of Chemicals (REACH) legislation and new technologies require a shift in the way in which safety assessments are conducted. Integrated testing strategies (ITSs) help in providing such a framework. Many of the ITS building blocks are already in use, but the concepts for their integration and application in a regulatory setting have yet to be fully implemented. This paper describes a feasibility study investigating how a combination of in silico, in vitro, and in vivo information could be applied in the assessment of skin irritation hazard. Therefore, a database of 100 existing and new chemicals was compiled. A number of strategies, both animal-free and inclusive of animal data were constructed and subsequently evaluated considering predictive capacities, severity of misclassifications and testing costs. Comparison of constructed ITS based on these assessment parameters identified best performing strategies for chemical classification. However, defining the in vivo test as the reference test limited the evaluation of the ITS inclusive of animal data. This study demonstrated that ITS can be constructed, evaluated and compared in a systematic fashion. To promote ITS, further guidance on construction and multi-parameter evaluation need to be developed.

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    ABSTRACT: In vitro alternative tests aiming at replacing the traditional animal test for predicting the irritant potential of chemicals have been developed, but the assessing parameters or endpoints are still not sufficient. To discover novel endpoints for skin irritation responses, 2DE-based proteomics was used to analyze the protein expression in human skin exposed to sodium lauryl sulfate (SLS) following the test protocol of the European Centre for the Validation of Alternative Methods (ECVAM) in the present study. HSP27 was up-regulated most significantly among the eight identified proteins, consistent with our previous reports. Acid and basic chemicals were applied on human skin for further validation and results showed that the up-regulated expression of HSP27 was induced in 24 h after the exposure. Skin-equivalent constructed with fibroblasts, basement membrane and keratinocytes was used to investigate the potential of HSP27 as a biomarker or additional endpoint for the hazard assessment of skin irritation. Our skin-equivalent (Reconstructed Organotypic Skin Model, ROSM) had excellent epidermal differentiation and was suitable for the skin irritation test. HSP27 also displayed an up-regulated expression in the ROSM in 24 h after the irritants exposure for 15 min. All these results suggest that HSP27 may represent a potential marker or additional endpoint for the hazard assessment of skin irritation caused by chemical products.
    Toxicology Letters 01/2014; · 3.15 Impact Factor
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    ABSTRACT: Despite the fact that toxicology uses many stand-alone tests, a systematic combination of several information sources very often is required: Examples include: when not all possible outcomes of interest (e.g., modes of action), classes of test substances (applicability domains), or severity classes of effect are covered in a single test; when the positive test result is rare (low prevalence leading to excessive falsepositive results); when the gold standard test is too costly or uses too many animals, creating a need for prioritization by screening. Similarly, tests are combined when the human predictivity of a single test is not satisfactory or when existing data and evidence from various tests will be integrated. Increasingly, kinetic information also will be integrated to make an in vivo extrapolation from in vitro data. Integrated Testing Strategies (ITS) offer the solution to these problems. ITS have been discussed for more than a decade, and some attempts have been made in test guidance for regulations. Despite their obvious potential for revamping regulatory toxicology, however, we still have little guidance on the composition, validation, and adaptation of ITS for different purposes. Similarly, Weight of Evidence and Evidence-based Toxicology approaches require different pieces of evidence and test data to be weighed and combined. ITS also represent the logical way of combining pathway-based tests, as suggested in Toxicology for the 21st Century. This paper describes the state of the art of ITS and makes suggestions as to the definition, systematic combination, and quality assurance of ITS.
    ALTEX. 01/2013; 30(1):3-18.
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    ABSTRACT: Most animal experiments on cosmetics safety are prohibited and since March 2013, this obligation includes sensitization tests. However, until now there has been no validated alternative in vitro method. In this work, 400 compounds used in the cosmetic industry were selected to cover the greatest diversity of structures, biological activities and sensitizing potential. These molecules were submitted to a series of tests aimed at reproducing essential steps in sensitization and to distinguish between sensitization and irritations, i.e., transcutaneous permeation (factor A), haptenation (factor B), sensitization cytokines production (factor C) and acute toxicity (factor D). The transcutaneous diffusion was measured on human skin explants using Franz cells. Haptenation was tested in solution on human serum albumin. Sensitization cytokine production was investigated by measurement of interleukin-18 release by keratinocytes. Acute toxicity was determined using an 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(75) cell viability test. As only sufficiently stable, soluble and detectable compounds are usable, 33, 72, 68 and 68 molecules were finally tested on factors A, B, C and D, respectively, and 32 were completely screened by the four factors. The individual correlation of the four factors with the reference in vivo tests was limited but the combination of these factors led to a correlation between in vivo and in vitro assays of 81.2% and the safety of the test (risk of false negative) reached 96.8%. The techniques employed are simple and inexpensive and this model of four tests appears as a promising technique to evaluate in vitro the skin sensitization potential of unknown molecules. Copyright © 2014 John Wiley & Sons, Ltd.
    Journal of Applied Toxicology 02/2014; · 2.60 Impact Factor


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