Published under the OECD guidelines on responsible business conduct for multinational enterprises (OECD guidelines) The standard “OECD TG 431 In vitro skin irritation: Reconstructed human epidermis (RHE) test method” describes a test method that allows the identification of corrosive chemicals and mixtures and, when supported by a weight of evidence determination using other available information, the identification of non-corrosive substances and mixtures. This test protocol also demonstrates the distinction between severe and less severe skin corrosives. This test method does not require the use of live animals or animal tissue for the assessment of skin corrosivity.
-test-yontemi.jpg "OECD TG 431 In Vitro Skin Irritation: Reconstructed Human Epidermis (RhE) Test Method")
Skin corrosion refers to the production of irreversible skin damage, manifested as visible necrosis from the epidermis to the dermis, following application of a test chemical. The OECD TG 431 standard provides an in vitro procedure that allows the identification of non-corrosive and corrosive substances and mixtures in accordance with the globally harmonized system of classification and labeling of chemicals. It also allows for partial sub-categorization of corrosives.
The assessment of the skin corrosion potential of chemicals has often involved the use of laboratory animals. However, in addition to the OECD TG 431 standard, the OECD TG 430 and OECD TG 435 standards have also been validated and accepted for testing the corrosion potential of chemicals. Furthermore, the OECD TG 439 standard has been developed for in vitro testing of skin irritation potential. A document on integrated testing and assessment approaches for skin corrosion and irritation describes several modules that group information sources and analysis tools and provide guidance on how to integrate and use existing test and non-test data for the assessment of the skin irritation and skin corrosion potential of chemicals, and recommend an approach when further testing is required.
This standard addresses the human health endpoint skin corrosion. It uses reconstructed human epidermis (RhE) (derived from human non-transformed epidermal keratinocytes) that closely mimics the histological, morphological, biochemical and physiological characteristics of the upper layers of human skin, the epidermis.
The OECD TG 431 standard includes five validated test methods using commercially available RhE models.
In this test, the test chemical is applied topically to a three-dimensional RhE model composed of cultured, non-transformed, human-derived epidermal keratinocytes to create a multilayered, highly differentiated model of the human epidermis. It consists of regular basal, spiny, and granular layers and a multilayered stratum corneum containing intercellular lamellar lipid layers representing major lipid classes similar to those found in vivo.
Two tissue replicates are used for each treatment (exposure time) and controls. Corrosive substances are defined by their ability to produce a decrease in cell viability below defined threshold levels at specified exposure times. Coloured chemicals can also be tested using an HPLC (high performance liquid chromatography) procedure. The principle of the human skin model test method is based on the assumption that corrosive chemicals can penetrate the stratum corneum by diffusion or erosion and are cytotoxic to the underlying cell layers. Cell viability is measured by the enzymatic conversion of the vital dye MTT to a blue formazan salt, which is measured quantitatively after removal from the tissues. RhE-based skin irritation test methods have been shown to detect in vivo skin irritation effects assessed in rabbits according to the OECD TG 404 standard.
Prior to routine use of any of the five validated RhE test methods conforming to this standard, laboratories must demonstrate their proficiency by correctly classifying the proposed proficiency substances conforming to this standard. Where a method is used for subclassification, the correct subcategorization should also be demonstrated. In cases where a listed substance is not available or is justified, another substance for which adequate in vivo and in vitro reference data are available may be used.
The test methods described in this standard are:
Among the numerous tests, measurements, analyses and evaluation studies that our organization has carried out for businesses in various sectors, our organization also provides testing services defined in the “OECD TG 431 In vitro skin irritation: Reconstructed human epidermis (RHE) test method” standard with its trained and expert staff and advanced technological equipment.
To get an appointment, to get more detailed information or to request an evaluation, you can ask us to fill in our form and reach you.
EUROLAB reporting and certification activities, United Accreditation Foundation (UAF), Turkish Accreditation Agency (TÜRKAK), Enterprise Accreditation Foundation (EAF) based on the accreditation provided by its institution. The Enterprise Accreditation Foundation (EAF) is also a signatory to the United Nations (UN GLOBAL COMPACT).
