Validation study of a new reconstructed human epidermis model EPiTRI for in vitro skin irritation test according to OECD guidelines

Following the global trend of reducing animal testing, various reconstructed human epidermis (RHE) models for skin irritation test (SIT) have been developed, verified, validated and included in OECD TG 439. We developed a new RHE called EPiTRI and a SIT method using EPiTRI (EPiTRI-SIT model) following the OECD guidelines. EPiTRI possesses morphological, biochemical and physiological properties similar to human epidermis with well-differentiated multilayered viable cells with barrier function. The EPiTRI-SIT model was tested for 20 reference chemicals in Performance Standard of OECD TG 439 (GD 220), showing good predictive capacity with 100% sensitivity, 70% specificity and 85% accuracy. EPiTRI had sensitivity in detecting di-n-propyl disulphate, as an irritant chemical (UN GHS Category 2), whereas most validated reference methods detected it as a non-irritant. An international validation study of EPiTRI-SIT was conducted in four laboratories to confirm the within- and between-laboratory reproducibility, as well as predictive capacity. The phase I/II within-laboratory and between-laboratory reproducibility was 100%/95% and 95%, respectively. The overall sensitivity, specificity and accuracy of EPiTRI-SIT was 96%, 70% and 83%, respectively, which fulfilled the OECD criteria. Thus, EPiTRI, meets the criteria of Performance Standards of OECD TG 439 (GD 220) and is suitable for screening irritating chemicals in vitro.     

Employment of cytology for in vitro skin irritation test using a reconstructed human epidermis model,Keraskin™

Skin irritation tests using reconstructed human epidermis (RhE) employ viability as an endpoint, but color interference or borderline results are often problematic. We examined whether the cytology of cells from treated RhE could determine skin irritancy. Six chemicals (three irritants; DnP, 1-B, PH, three non-irritants; DP, APA, HS) were evaluated in a RhE, Keraskin™. DP, HS, and PH were clearly classified with viability, but DnP, 1-B, and APA were often falsely determined, due to borderline values falling near the cutoff, 50%. In histology, the tissues treated with DnP, 1-B, and PH showed erosion of the stratum corneum, vacuolization, and necrosis in the basal layer. DP- and HS-treated tissues showed relatively normal morphology but APA induced necrosis similar to irritants. Cytology revealed that DnP, 1-B or PH depleted cells and induced irregular and abnormal cell shapes. In contrast, relatively regular and normal shapes and clear distinction between the nucleus and cytoplasm was observed for DP, APA and HS. To further confirm it, additional 10 substances, including false positives from OECD TG 439, were tested. Overall (16 substances in total), cytology: total area predicted the skin irritancy of test chemicals with the highest accuracy (87.5%) followed by cytology: cell count (81.3%), histology (75%) and viability (68.8%), confirming the utility of cytology as an alternative endpoint in the skin irritation test using RhE.     

Catch-up validation study of an in vitro skin irritation test method based on an open source reconstructed epidermis (phase II)

To replace the Draize skin irritation assay (OECD guideline 404) several test methods based on reconstructed human epidermis (RHE) have been developed and were adopted in the OECD test guideline 439. However, all validated test methods in the guideline are linked to RHE provided by only three companies. Thus, the availability of these test models is dependent on the commercial interest of the producer. To overcome this limitation and thus to increase the accessibility of in vitro skin irritation testing, an open source reconstructed epidermis (OS-REp) was introduced. To demonstrate the capacity of the OS-REp in regulatory risk assessment, a catch-up validation study was performed. The participating laboratories used in-house generated OS-REp to assess the set of 20 reference substances according to the performance standards amending the OECD test guideline 439. Testing was performed under blinded conditions. The within-laboratory reproducibility of 87% and the inter-laboratory reproducibility of 85% prove a high reliability of irritancy testing using the OS-REp protocol. In addition, the prediction capacity was with an accuracy of 80% comparable to previous published RHE based test protocols. Taken together the results indicate that the OS-REp test method can be used as a standalone alternative skin irritation test replacing the OECD test guideline 404.     

重组人皮肤模型在化妆品皮肤刺激性评价中的应用研究

目的 探讨重组人皮肤模型应用于化妆品体外皮肤刺激性评价的可行性.方法 以重组人皮肤模型(EpiSkinTM)为受试模型,在对10个已知刺激性分类的标准化学品进行方法验证的基础上,再根据化妆品的使用特性对23个产品进行皮肤刺激性分类评价,其中6个基础型化妆品和10个美容型化妆品暴露18 h、7个清洁型化妆品分别暴露18、...     

Regulatory accepted but out of domain: In vitro skin irritation tests for agrochemical formulations

Several in vitro methods have gained regulatory acceptance for the prediction of skin irritation and corrosion. However, the test guidelines for the majority of in vitro methods do not state whether they are applicable to agrochemical formulations. Hence, we would like to share the results from our routine skin corrosion and irritation testing of agrochemical formulations in which both in vitro (according to OECD TG 431 and OECD TG 439) and in vivo (according to OECD TG 404) tests were conducted as regulatory requirements. The in vitro skin irritation test did not correlate well with the CLP classification by in vivo results (44% sensitivity, 60% specificity, and 54% accuracy, based on 65 data pairs). This indicates a lack of applicability of the current protocol of the in vitro skin irritation test for agrochemical formulations. The data set did not contain formulations which were skin corrosive in vivo and hence its applicability could not be assessed. The correlation of in vitro skin corrosion testing to formulations which were not corrosive in vivo was, however, high (95% specificity based on 81 data pairs).     

Enhanced predictive capacity using dual-parameter chip model that simulates physiological skin irritation

Current alternatives to animal testing methods for skin irritation evaluation such as reconstructed human epidermis models are not fully representing physiological response caused by skin irritants. Skin irritation is physiologically induced by the dilation and increased permeability of endothelial cells. Thus, our objectives were to mimic physiological skin irritation using a skin-on-a-chip model and compare predictive capacities with a reconstructed human epidermis model to evaluate its effectiveness. To achieve our goals, the skin-on-a-chip model, consisting of three layers representing the epidermal, dermal and endothelial components, was adapted. Cell viability was measured using the OECD TG 439 protocol for test substance evaluation. The tight junctions of endothelial cells were also observed and measured to assess physiological responses to test substances. These parameters were used to physiologically evaluate cell-to-cell interactions induced by test substances and quantify model accuracy, sensitivity, and specificity. Based on in vivo data, the classification accuracy of twenty test substances using a dual-parameter chip model was 80%, which is higher than other methods. Besides, the chip model was more suitable for simulating human skin irritation. Therefore, it is important to note that the dual-parameter chip model possesses an enhanced predictive capacity and could serve as an alternative to animal testing for skin irritation.     

The suitability of reconstructed human epidermis models for medical device irritation assessment: A comparison of In Vitro and In Vivo testing results

The ISO 10993 standards on biocompatibility assessment of medical devices discourage the use of animal tests when reliable and validated in vitro methods are available. A round robin validation study of in vitro reconstructed human epidermis (RhE) assays was performed as potential replacements for rabbit skin irritation testing. The RhE assays were able to accurately identify strong irritants in dilute medical device extracts. However, there was some uncertainty about whether RhE tissues accurately predicted the results of the rabbit skin patch or intracutaneous irritation test. To address that question, this paper presents in vivo data from the round robin and subsequent follow-up studies. The follow-up studies included simultaneous in vitro RhE model and in vivo testing of round robin polymer samples and the results of dual in vitro/in vivo testing of currently marketed medical device components/materials. Our results show for the first time that for both pure chemicals and medical device extracts the intracutaneous rabbit test is more sensitive to detect irritant activity than the rabbit skin patch test. The studies showed that the RhE models produced results that were essentially equivalent to those from the intracutaneous rabbit skin irritation test. Therefore, it is concluded that RhE in vitro models are acceptable replacements for the in vivo rabbit intracutaneous irritation test for evaluating the irritant potential of medical devices.     

Establishment of a new in vitro test method for evaluation of eye irritancy using a reconstructed human corneal epithelial model,LabCyte CORNEA-MODEL

Finding in vitro eye irritation testing alternatives to animal testing such as the Draize eye test, which uses rabbits, is essential from the standpoint of animal welfare. It has been developed a reconstructed human corneal epithelial model, the LabCyte CORNEA-MODEL, which has a representative corneal epithelium-like structure. Protocol optimization (pre-validation study) was examined in order to establish a new alternative method for eye irritancy evaluation with this model. From the results of the optimization experiments, the application periods for chemicals were set at 1 min for liquid chemicals or 24 h for solid chemicals, and the post-exposure incubation periods were set at 24 h for liquids or zero for solids. If the viability was less than 50%, the chemical was judged to be an eye irritant. Sixty-one chemicals were applied in the optimized protocol using the LabCyte CORNEA-MODEL and these results were evaluated in correlation with in vivo results. The predictions of the optimized LabCyte CORNEA-MODEL eye irritation test methods were highly correlated with in vivo eye irritation (sensitivity 100%, specificity 80.0%, and accuracy 91.8%). These results suggest that the LabCyte CORNEA-MODEL eye irritation test could be useful as an alternative method to the Draize eye test.     

Evaluation of fibrin-based dermal-epidermal organotypic cultures for in vitro skin corrosion and irritation testing of chemicals according to OECD TG 431 and 439

Reconstructed human epidermis (RhE) models have been used for in vitro testing of the potential harmful effects of exposure to chemical compounds on health. In the past, skin irritation and corrosion were evaluated in animal models; however, in recent years, due to the bioethics implications of the method and, to minimize the use of experimental animals, alternative procedures have been proposed. The Organisation for Economic Co-operation and Development (OECD) in its test guidelines (TG) 431 and 439 indicates the requirements for validating new methods for the evaluation of skin corrosion and irritation, respectively. Here, we present an in-house human dermal-epidermal model, useful for the performance of these tests. Using the methods described in this work, it was possible to obtain human fibrin-based dermal-epidermal organotypic skin cultures (ORGs) displaying similar histological characteristics to native skin and expressing specific differentiation epithelial proteins. The end points to classify a substance as irritant or corrosive were cell viability evaluated by MTT assay, and cytokine release measured by BD CBA for human inflammatory cytokines. According to the MTT test, the ORGs correctly classified irritating and corrosive substances. Moreover, the cytokine release assay was difficult to interpret in the context of testing chemical hazard classification. Further experiments are needed to validate this new model for the evaluation of surfactants because the fibrin matrix was affected in the presence of these substances.     

KeraSkin™-VM: A novel reconstructed human epidermis model for skin irritation tests

Several alternative in vitro methods to evaluate skin irritants have been developed recently. In July 2010, OECD officially endorsed the validated reference method (VRM) that uses reconstituted human epidermis (RhE) models as replacements for the in vivo skin irritation test. This study evaluated the KeraSkin™-VM model, a novel human epidermis model that was reconstructed with Asian skin tissue using 20 reference chemicals according to the OECD TG 439 performance standard. The test chemicals were applied to the epidermal surface side for 45 min and then rinsed, and then incubated for 42 h post-treatment. An overall accuracy of 80%, sensitivity of 90% and specificity of 70% were obtained when the results from KeraSkin™-VM were compared with UN GHS categories, which was comparable to the EpiDerm™ Skin irritation test (SIT) rates. Furthermore, KeraSkin™-VM demonstrated good performance in terms of within-laboratory reproducibility and predictive capacity to screen skin irritants.     

Dermo-epidermal organotypic cultures for in vitro evaluation of skin irritation and corrosion

In recent years, in-vitro skin models for chemical hazard identification have been developed. Most of them consist only of human keratinocytes, neglecting the contribution of other skin constituents. Cultures containing the dermal and epidermal component provide an attractive system to investigate, in a more realistic model, toxicological responses, which represents a distinct advantage over keratinocytes-based models that do not mimic faithfully the in vivo environment.This study aimed to validate dermo-epidermal organotypic cultures (ORGs) as a platform to perform irritation and corrosion tests. Skin models were constructed by seeding keratinocytes on fibroblast-containing fibrin gels. After 21 days, the ORGs were evaluated histologically, and the irritant and corrosion potential was determined by means of viability measurements (MTT assay) and cytokine release, according to 431 and 439 OECD tests guidelines.Skin models showed similar histological characteristics to native skin and were able to classify different substances with high accuracy, showing their applicability to skin irritation and corrosion tests. Although cytokines release seems to be chemical-dependent, a tendency was observed, leading to the improvement of the prediction capacity. Nevertheless, further studies should be done to reduce variability in order to increase prediction capacity.     

Exploration and comparison of in vitro eye irritation tests with the ISO standard in vivo rabbit test for the evaluation of the ocular irritancy of contact lenses

In an effort to explore the use of alternative methods to animal testing for the evaluation of the ocular irritancy of medical devices, we evaluated representative contact lenses with the bovine corneal opacity and permeability test (BCOP) and an in vitro eye irritation test using the three-dimensionally-reconstructed human corneal epithelium (RhCE) models, EpiOcular™ and MCTT HCE™. In addition, we compared the obtained results with the ISO standard in vivo rabbit eye irritation test (ISO10993-10). Along with the positive controls (benzalkonium chloride, BAK, 0.02, 0.2, and 1%), the extracts of 4 representative contact lenses (soft, disposable, hard, and colored lenses) and 2 reference lenses (dye-eluting and BAK-coated lenses) were tested. All the lenses, except for the BAK-coated lens, were determined non-irritants in all test methods, while the positive controls yielded relevant results. More importantly, BCOP, EpiOcular™, and MCTT HCE™ yielded a consistent decision for all the tested samples, with the exception of 0.2% BAK in BCOP, for which no prediction could be made. Overall, all the in vitro tests correlated well with the in vivo rabbit eye irritation test, and furthermore, the combination of in vitro tests as a tiered testing strategy was able to produce results similar to those seen in vivo. These observations suggest that such methods can be used as alternative assays to replace the conventional in vivo test method in the evaluation of the ocular irritancy of ophthalmic medical devices, although further study is necessary.     

Evaluation of a tiered in vitro testing strategy for assessing the ocular and dermal irritation/corrosion potential of pharmaceutical compounds for worker safety

Introduction: Irritation reactions are a frequently reported occupational illness. The potential adverse effects of pharmaceutical compounds (PCs) on eye and skin can now be assessed using validated in vitro methods.

Objectives: Our overall aim is to reduce animal testing by replacing the historically utilized in vivo test methods with validated in vitro test methods which accurately determine the ocular and dermal irritation/corrosion potential of PCs to inform worker safety within the pharmaceutical space. Bristol–Myers Squibb (BMS) and the Institute for In Vitro Sciences (IIVS) have therefore conceptualized and internally qualified a tiered in vitro testing strategy to inform occupational hazards regarding eye and skin irritation and corrosivity of PCs. For the small scale pre-qualification phase, we paired historical in vivo and newly generated in vitro data for 15 PCs to determine the predictive capacity of in vitro assays already validated for the eye and skin irritation/corrosion endpoints and accepted for certain regulatory submissions. During the post-qualification phase, a group of 24 PCs were subjected exclusively to the developed tiered testing strategy, which is based on three Organisation for Economic Co-operation and Development (OECD) in vitro methods.

Materials and methods: The qualified in vitro testing strategy utilizes the Corrositex^® assay for the corrosivity (OECD TG 435), the Bovine Corneal Opacity and Permeability (BCOP) assay for ocular irritation (OECD TG 437), and the EpiDerm? tissue model-based Skin Irritation Test (SIT) for dermal irritation (OECD TG 439). In the first step, the pH of each PC was determined. For compounds with pH extremes ≥11 or ≤2, the Corrositex^® assay was generally conducted first. For compound(s) that were incompatible with or were negative in the Corrositex^® assay or had pH values between 2 and 11, the BCOP assay and SIT were performed first.

Results: The results of the tiered testing strategy’s qualification phase demonstrated that the BCOP assay is sensitive enough to identify a wide range of eye irritation/corrosion potentials and its over-prediction rate was considered acceptable to inform occupational hazards and ensure the proper handling practices of PCs. The SIT correctly predicted the skin irritation potential of 14 out of the 15 PCs included in the qualification phase, only over-predicting one PC. In the post-qualification phase, four PCs out of four tested were predicted corrosive by the Corrositex^® assay and thus no further testing was needed or conducted. The rest of the PCs were evaluated in the BCOP assay (both neat and as a 20% dilution), with the higher response being used for hazard classification. Four PCs were determined to be severe eye irritants, 1 a moderate irritant, 8 were mild irritants, and 8 were non-irritants. The same set of PCs was evaluated using the SIT and were classified as non-irritants to skin. These results are consistent with the BMS historical in vivo results showing a very low number of PCs as skin irritants.

Conclusions: This tiered in vitro testing strategy, which replaces the use of animal studies, was found to be reasonably accurate in its predictive capacity when compared to historical in vivo results and represents a conservative and reliable platform that can be utilized for the prediction of ocular and dermal irritation/corrosion potential of PCs and for subsequent GHS classification and worker safety hazard communications.     

Evaluation of the cutaneous-irritation potential of 56 compounds

The primary cutaneous irritation of 56 chemicals was tested in the rabbit using three different procedures. The three protocols selected for the tests were the method published by the French authorities for the testing of cosmetics and toiletries (Journal Officiel 21 April 1973, p. 3862; ibid 5 June 1973, p. 3953) and the methods proposed for the testing of chemicals by the Association Française de Normalisation (AFNOR) and, in 1979, by the Organisation for Economic Co-operation and Development. The results of the three sets of tests were compared and the effects of differences in procedure and numbers of animals were studied, together with the possible relation between irritancy and the pH of the test material. It was concluded that the AFNOR protocol best met the requirements for such tests and that gloves should be worn for the handling of all substances classified as moderately or severely irritant on that scale.     

The agarose diffusion method for ocular irritancy screening: cosmetic products,part i

Abstract

The cosmetics industry is the target of criticism from animal welfare and animal rights groups for its use of the Draize eye irritancy test to substantiate the safety of cosmetic ingredients and products. To date, the two main difficulties in the development of alternatives to the Draize test have been a lack of high correlation between in vitro alternative test results and in vivo Draize test results, and the inability to present typical cosmetic formulations to these alternative test systems. For these reasons it occurred to us to test cosmetic products with the agarose diffusion test. This test has been scientifically validated and is well-established as an in vitro alternative test to screen the toxicity of plastics in medical devices. Sixteen cosmetic products initially tested with the Draize eye irritancy test and skin irritation test were tested in the agarose diffusion method to determine whether zone of lysis and/or cell toxicity could be correlated with either Draize eye test results or primary irritation index (PII). Even though the sample size was small (16 cosmetic products exclusive of controls), 80% (4/5) of the samples positive in the Draize eye test were predicted by the agarose diffusion method. Eighty-two percent (9/11) of the Draize negative samples were predicted by this same method, for an overall correlation of 81 % between the agarose diffusion method and the results in the Draize eye irritancy test. Only 19% of the test materials were false positives (2/16) or false negatives (1/16), suggesting that the agarose diffusion model may be slightly more sensitive than the Draize eye method. No correlation between the agarose diffusion test and the primary skin irritation test results could be established. These results indicate a high degree of correlation between an in vitro screening test as an alternative to the Draize eye irritancy test and permit testing of oil-in-water emulsions (both pigmented and nonpigmented), water-based suspensions, petroleum-distillate-based suspensions, solutions, physical mixtures of waxes, and physical mixtures of dry powders in this alternative test system.     

Overview of animal test methods for skin irritation

Determining the irritant effects of chemicals in experimental animals provides the public with information on and protection against possible hazards that may arise from exposure of the human skin. Furthermore, the data obtained are used for registration and classification purposes. This paper reviews the methods proposed in the most important guidelines (OECD, EEC and FIFRA guidelines) and points out the critical experimental points. It shows that the introduction of OECD Guideline No. 404 can lead to a reduction in the number of test animals used for skin irritation testing.     

A catch-up validation study on reconstructed human epidermis (SkinEthic™ RHE) for full replacement of the Draize skin irritation test

Efforts to fully replace the in vivo Draize skin irritation test, according to the Directive 67/548/ECC or OECD TG 404, were reinforced with the seventh Amendment of the Cosmetic Directive and the REACh regulation. In 2007, the EpiSkin™ test method was scientifically validated and recognized as the stand alone method to discriminate skin irritants (R38) from non-irritants (no label) according to the definition of the EU risk phrases. An ECVAM performance standards (PS) document was defined to evaluate the accuracy and reliability of other analogous test methods (ECVAM SIVS, May 2007). The present test was designed to determine the reliability and relevance of the Reconstructed Human Epidermis (RHE) model commercialized by SkinEthic™. The RHE skin irritation test method consisted to topically apply topically the test substances for 42 min followed by a 42 h post-incubation. The main selected endpoint was the cell viability (MTT reduction), with a threshold of 50% viability. The RHE test method showed a good intra and inter-laboratory reproducibilities in a multicentric study involving three independent laboratories. The SkinEthic™ RHE test method showed to be relevant and reliable with a sensitivity of 90% and a specificity of 80% (MTT only) and was not improved by integrating another endpoint such as IL-1α. The overall accuracy was 85% resulting in the recognition of the SkinEthic™ RHE test method, by the ECVAM Scientific Advisory Committee in November 2008, as a stand alone replacement test method for the Draize rabbit in vivo test, as a screen, or as part of a sequential testing strategy in a weight of evidence approach, for classifying non-irritant and irritant test substances, depending on country requirements.     

Non-occlusive topical exposure of human skin in vitro as model for cytotoxicity testing of irritant compounds

Testing of irritant compounds has traditionally been performed on animals and human volunteers. Animal testing should always be restricted and for skin irritancy mice and rabbits hold poor predictive value for irritant potential in humans. Irritant testing on human volunteers is restricted by the duration subjects can be exposed, and by the subjectivity of interpreting the visual signs of skin irritation. We propose an irritant testing system using viable human full thickness skin with the loss of cell viability in the exposed skin area as end point measurement. Skin was exposed to sodium dodecyl sulfate (SDS) at 20% concentration by non-occluded topical exposure to establish a positive control response and subsequent test compounds were statistically compared with the 20% SDS response. Cell viability and metabolism were measured with 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The model presents correlation between increased concentration of SDS and decreased viability of cells in the exposed skin area (R²?=?0.76). We propose the model to be used for cytotoxicity testing of irritant compounds. With fully intact barrier function, the model comprises all cells present in the skin with quantifiable end point measurement.     

A prevalidation study on the in vitro skin irritation function test (SIFT) for prediction of acute skin irritation in vivo: results and evaluation of ECVAM Phase III.

A prevalidation study sponsored by the European Centre for the Validation of Alternative Methods (ECVAM) on in vitro tests for acute skin irritation is aimed at identifying non-animal tests capable of discriminating irritants (I) from non-irritants (NI), as defined according to European Union and OECD. This paper reports on Phase III for one of the methods, the skin integrity function test (SIFT), assessing the protocol performance of the SIFT, in terms of reproducibility and predictive ability, in three laboratories. The barrier function properties of excised mouse skin were determined using a set of 20 coded chemicals (10 I, 10 NI), using the endpoints of trans-epidermal water loss (TEWL) and electrical resistance (ER). The basis of the SIFT prediction model is if the ratios of the pre- and post-application values for either TEWL or ER are greater than five-fold, then the test chemical is deemed irritant (I). If the ratio of both parameters is less than five-fold then the chemical is deemed non-irritant (NI). Analysis of variance (ANOVA) indicated that the intra-lab reproducibility was acceptable but that the inter-lab reproducibility was not. Overall, the SIFT test under-predicted the irritancy of the test chemicals chosen for Phase III with an overall accuracy of only 55%. The sensitivity value (ability to correctly predict I) was only 30%. The specificity (ability to predict NI) of the test was better at 80%. A retrospective examination of the SIFT results was undertaken using Student's t-test and a significance level of P<0.05 to predict an irritant based on changes in the TEWL ratio values. This improved the predictivity of the SIFT test, giving a specificity of 60%, a sensitivity of 80% and an overall accuracy of 70%. Appropriate modifications to the prediction model have now been made and the SIFT will be re-examined in a new validation exercise to investigate the potential of this non-animal method to predict acute skin irritation potential.     

Dual Characteristics of Skin Care Creams Evaluated by Two In-Vivo Human Experimental Models

The use of skin care creams is a well documented protection measure to reduce the risk of barrier damage and contact dermatitis from exogenous contact with skin irritants. Before choosing a skin care cream two aspects should be considered: a) Is the product able to reduce irritant reactions caused by the irritant, and b) is the product well tolerated, also on damaged skin. Both aspects can be evaluated by experimental models in human volunteers. We used two standard experimental designs to compare six commercially available skin care products: a) the chamber scarification test, designed to assess the irritancy potential, and b) the repeated short-time occlusive irritation test (ROIT), developed to evaluate the efficacy of skin care creams. The results showed that a high score in the chamber scarification test for skin irritation was not necessarily correlated to the products' ability to impede sodium lauryl sulfate (SLS)-induced irritant skin reactions. Three products were shown to both have a low irritancy potential and be capable of reducing skin barrier damage induced by SLS, and one product had both an irritant potential on scarified skin and also a modest capability to reduce skin irritation induced by SLS. The use of both test methods, chamber scarification and ROIT, gives valuable information on skin compatibility and efficacy of skin care creams. The clinical relevance of the test results can only be determined by comparing products with high and low scores in both tests in controlled clinical experiments with subjects at risk of developing irritant contact dermatitis.