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Evaluation of the harmlessness of finished textiles

An increasing number and variety of functionalised textiles (perfumed, FR, stain-repellent, waterproof, antibacterial, slimming, anti-UV…) are being marketed. However, it is essential that these textiles are harmless. It is therefore advisable to check the tissue compatibility of finished textile materials and to verify whether new chemical substances used to functionalise textiles do not involve any risks to the skin (cytotoxicity, irritation, …).

Evaluation of cell toxicity (cytotoxicity)

Test method

ISO 10993-5 "Biological evaluation of medical devices – part 5 – Tests for in vitro cytotoxicity"
In vitro culture: mouse fibroblasts (cells L929)

This test method has originally been designed to verify the release of harmful substances from medical devices and can also be used to evaluate the safety of textile materials in general.

This test is a very sensitive one because of the in culture (in vitro) isolation of mammal cells and the absence of protective mechanisms supporting the body cells.

With this test we can screen materials (making a difference between reactive and non-reactive materials) to predict the biocompatibility, to compare different batches, to replace a certain material and to determine the impact of a production change…

Principle

Mammal cells are brought into contact with a textile extract. The cell toxicity is then determined by measuring the viability of the cells by means of a MTT-test. This test measures the redox potential of the active living cells through a colorimetric reaction (reduction of MTT to coloured formosan). The intensity of the measured colourisation therefore corresponds with the number of living cells present during the test and with their metabolic activity.

Evaluation

The results are expressed as a percentage of 100% viability (check). If the average cell viability of the tested samples is less than 70%, the textile extract is considered cytotoxic.