Vitro cell culture test for allergens in textiles
Media reports keep on raising the suspicion that textiles can trigger allergies. The chief culprit is generally believed to be the dyestuffs they contain. So far, the safest way for textile producers to minimise this risk has been to test for known allergenic dyestuffs using substance-based testing for harmful substances, for example in accordance with the Oeko-Tex Standard 100. Consequently, there remains a residual risk where textiles dyes or chemical are used of which the allergenic potential is not yet known (e.g. imported goods not approved by Oeko-Tex).
This is why scientists have been working for decades on effect-based test methods, in order to be able not only to analyse a textile for specific allergens but also to assess the residual allergenic potential of other chemical byproducts and combinations of substances in textile products.
The researchers at the Institute for Hygiene and Biotechnology (IHB) at the Hohenstein Institute have now succeeded in reaching this stage: they have developed a simple selective in vitro cell culture test that, for the first time, can be used to reliably calculate the allergenic potential of textiles, for example where unknown dyes, dye components or other chemicals are used for which no sensitisation data is yet available.
Manufacturers will receive a certificate for those of their products that are tested successfully and they are allowed to endorse and advertise them using the Hohenstein quality label "Skin-friendly – suitable for allergy sufferers".
In order to test raw materials, textiles and other products, the scientists at the IHB use special immune cells which act like "guard cells" for the skin. These immune cells are able to absorb external antigens penetrating the skin from neighbouring cells in the epidermis, identify them and trigger the appropriate immune response. They are therefore critical in deciding on the starting point for an allergy.
In the test, the guard cells are kept in the cell culture and, as they do in the human skin, they perform the job of identifying a chemical as an allergen. If they recognise that a substance released from the textile is alien to the body, they present the allergen together with specific marker molecules on their cell surface. From these marker molecules it is possible to quantify the critical process of identifying the substance and classifying it as an allergen.
The new test method can be used for a wide range of in vitro product testing when it is a question of identifying the sensitisation risks (allergenic potential). It perfectly supplements the epicutaneous test, an established and standardised (EN ISO 10993-10) verification procedure for contact allergies, already used at the Hohenstein Institute for textile medical products.
However, compared with the skin test, the new in vitro procedure has the clear advantage that it detects all the allergenic effects elicit by the textiles and so allows allergens to be tested for that cannot be identified in any other way (e.g. unknown byproducts of the reaction and breakdown of chemical substances).
This means, for example, that even native allergens can be tested in the liquid or solid state, making the test an interesting in vitro alternative for calculating the allergenic potential of chemicals for which toxicology information has to be provided under REACh legislation in the form of a substance safety report.
The new test method represents a useful addition to the testing for harmful substances carried out under Oeko-Tex Standard 100 with a view to providing maximum product safety for the consumer.
It means that, along with the already established tests for cell damage (cytotoxicity), DNA damage (genotoxicity) and irritation, there is now a fourth effect-based test available at the Hohenstein Institute, which can give a proper scientific answer to questions about the safety and compatibility of textiles – that is to say, differentiating between the four risks.
The biological risks in medical devices are also analysed selectively in separate test systems under the EN ISO 10993 standard, with regard to cell damage, DNA damage, irritation and allergies.
Textile products that are not harmful to health –
substance-based testing v. effect-based test methods