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Epiderm Skin Irritation Test - OECD TG 431, a Method to evaluate the safe Handling, Packing and Transport of Chemicals




The MTT test is a colorimetric viability test of the cells after the treatment of the target object. As a colorimetric assay for assessing cells' metabolic activity, the decrease in the number of living cells leads to a decrease in metabolic activity in the test culture. The test is based on the cleavage of the yellow tetrazolium salt MTT (3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide) forming a purple formazan. This decrease correlates directly with the amount of purple formazan produced, which is monitored by absorption.



Skin Irritation Overview

The skin is the largest human organ, but it is more than just a protective covering for the body. It consists of several layers and fulfills many vital functions. The living skin regenerates continuously and is metabolically active. One of the skin's essential functions is protecting the body from environmental hazards such as toxic or harsh chemicals.

The outermost layer of skin is the epidermis, consisting of about four layers of epithelial cells, the keratinocytes. The epidermal keratinocytes and connections between these cells form the skin's barrier, prohibiting substances to enter the skin and water and electrolytes leaking out of the body.

The products mentioned at the beginning, such as cosmetics, can cause skin irritation by passing through the outer layer of the skin, the stratum corneum, and migrating to the underlying layers, thereby toxically affecting these cells.

In turn, this leads to an immediate immune response, typically characterized by redness and itching or pain in the area in contact with the product.

Skin irritation tests determine the skin irritation potential of chemicals, drugs, cosmetics, biocides, and other substances such as personal care products and pharmaceuticals.

The test scope is essential for determining the safe handling, packaging, and transport of the substances
.

Categories for Skin Irritation

There are three distinct hazard categories 1-3 for skin irritation and corrosion. In addition to category 1 (corrosion), categories 2 and 3 refer to skin irritation. Category 2 stands for media being irritant, while category 3 is for mild irritant. The description below describes the properties of substances and tested mixtures for skin irritants.

Category 2 Irritant

Skin irritation occurs as reversible damage to the skin following exposure of up to 4 hours as monitored by data or human description.

Substance properties, structure, or activity, are already related to the mixture or pure substance have been classified as an irritant.

Positive results detected in a valid and accepted in vitro skin irritation test.

Animal experience or test data present for 2 of 3 tested animals, the test or mixture respectively cause reversible damage to the skin, underlying exposure of maximum four hours, at the conditions of having a mean value of more than 2.3 and < 4.0 for erythema/eschar or edema, or inflammation that lasts to the end of the observation period.

Category 3 Mild Irritant

Animal experience or test data indicating that for 2 of 3 tested animals, the test or mixture respectively cause reversible damage to the skin, underlying an exposure of maximum of four hours, at the conditions of having a mean value of more than 1.5, but less than 2.3 for erythema/eschar.

Skin Irritation Models

The European Commission has included several reconstructed human epidermis models for skin irritation tests in its regulations (see draft TG B 46). The cell models include monolayer cultures of human or animal skin cells (keratinocytes), multilayer (3-dimensional cultures of skin cells providing a barrier function like the skin surface, and co-culture models. Our epidemic irritation tests represent 3D models of human skin.

EpiDerm™ is a reconstituted three-dimensional model of the human epidermis (RhE) made up of human epidermal keratinocytes.

In its task, the RhE mimics the biochemical and physiological properties of the upper parts of the human skin exactly. Cell viability is measured by enzymatic conversion of the vital dye MTT into a blue formazan salt, which is measured quantitatively after extraction from tissues.

The skin irritation model can determine whether a chemical or ingredient in a product can penetrate the outer layer of the skin and have a cytotoxic effect on the cells below.

Skin Irritation Tests

The skin irritation test uses three-dimensional skin models to test for skin irritation. The underlying in vitro model is an excellent replacement for the in vivo tests performed on animals. Several in vivo tests for cosmetic ingredients are now banned for use in many areas.

The EpiDerm skin irritation test's objective is to predict the skin irritation potential of dedicated test substances to identify and classify the risk of skin irritation under the applicable guidelines.

Depending on the legal framework and the classification system used, this procedure can be used to determine the skin irritation of test substances as a stand-alone replacement test for in vivo skin irritation tests or as a partial replacement test within a graded test. The EpiDerm skin irritation test enables the distinction between irritants of category two and non-irritants.


Primacyt’s FICAM Skin Irritation Test is based on the applying the MatTek (MTT) in-vitro reconstructed human skin model for safety, effectiveness screening, and basic pre-clinical research.

In the case of an irritating test substance, a supplementary test using the in vitro skin corrosion test method may be required if data is generated within the framework of OECD TG 439.




Skin Irritation Overview

The skin is the largest human organ, but it is more than just a protective covering for the body. It consists of several layers and fulfills many vital functions. The living skin regenerates continuously and is metabolically active. One of the skin's essential functions is protecting the body from environmental hazards such as toxic or harsh chemicals.

The outermost layer of skin is the epidermis, consisting of about four layers of epithelial cells, the keratinocytes. The epidermal keratinocytes and connections between these cells form the skin's barrier, prohibiting substances to enter the skin and water and electrolytes leaking out of the body.

The products mentioned at the beginning, such as cosmetics, can cause skin irritation by passing through the outer layer of the skin, the stratum corneum, and migrating to the underlying layers, thereby toxically affecting these cells.

In turn, this leads to an immediate immune response, typically characterized by redness and itching or pain in the area in contact with the product.

Skin irritation tests determine the skin irritation potential of chemicals, drugs, cosmetics, biocides, and other substances such as personal care products and pharmaceuticals.

The test scope is essential for determining the safe handling, packaging, and transport of the substances
.

Categories for Skin Irritation

There are three distinct hazard categories 1-3 for skin irritation and corrosion. In addition to category 1 (corrosion), categories 2 and 3 refer to skin irritation. Category 2 stands for media being irritant, while category 3 is for mild irritant. The description below describes the properties of substances and tested mixtures for skin irritants.


Category 2 Irritant

Skin irritation occurs as reversible damage to the skin following exposure of up to 4 hours as monitored by data or human description.

Substance properties, structure, or activity, are already related to the mixture or pure substance have been classified as an irritant.

Positive results detected in a valid and accepted in vitro skin irritation test.

Animal experience or test data present for 2 of 3 tested animals, the test or mixture respectively cause reversible damage to the skin, underlying exposure of maximum four hours, at the conditions of having a mean value of more than 2.3 and < 4.0 for erythema/eschar or edema, or inflammation that lasts to the end of the observation period.

Category 3 Mild Irritant

Animal experience or test data indicating that for 2 of 3 tested animals, the test or mixture respectively cause reversible damage to the skin, underlying an exposure of maximum of four hours, at the conditions of having a mean value of more than 1.5, but less than 2.3 for erythema/eschar.

Skin Irritation Models

The European Commission has included several reconstructed human epidermis models for skin irritation tests in its regulations (see draft TG B 46). The cell models include monolayer cultures of human or animal skin cells (keratinocytes), multilayer (3-dimensional cultures of skin cells providing a barrier function like the skin surface, and co-culture models. Our epidemic irritation tests represent 3D models of human skin.

EpiDerm™ is a reconstituted three-dimensional model of the human epidermis (RhE) made up of human epidermal keratinocytes.

In its task, the RhE mimics the biochemical and physiological properties of the upper parts of the human skin exactly. Cell viability is measured by enzymatic conversion of the vital dye MTT into a blue formazan salt, which is measured quantitatively after extraction from tissues.

The skin irritation model can determine whether a chemical or ingredient in a product can penetrate the outer layer of the skin and have a cytotoxic effect on the cells below.

Skin Irritation Tests

The skin irritation test uses three-dimensional skin models to test for skin irritation. The underlying in vitro model is an excellent replacement for the in vivo tests performed on animals. Several in vivo tests for cosmetic ingredients are now banned for use in many areas.

The EpiDerm skin irritation test's objective is to predict the skin irritation potential of dedicated test substances to identify and classify the risk of skin irritation under the applicable guidelines.

Depending on the legal framework and the classification system used, this procedure can be used to determine the skin irritation of test substances as a stand-alone replacement test for in vivo skin irritation tests or as a partial replacement test within a graded test. The EpiDerm skin irritation test enables the distinction between irritants of category two and non-irritants.


Primacyt’s FICAM Skin Irritation Test is based on the applying the MatTek (MTT) in-vitro reconstructed human skin model for safety, effectiveness screening, and basic pre-clinical research.

In the case of an irritating test substance, a supplementary test using the in vitro skin corrosion test method may be required if data is generated within the framework of OECD TG 439.





You have arrived at this page because you are interested in the Rhe model, skin irritation tests, catch-up validation studies, vitro skin irritation and tests, acute skin irritation and test methods, and other information. Your focus areas cover reconstructed human and animal epidermis, OECD test guidelines, skin models, skin corrosion and toxicity tests, as well as the skin irritation potential and skin irritation test sit.