TESTING
a quantitative indication of a product’s irritation potential. A longer time for the product to reduce tissue viability by 50% suggests a milder product, while a shorter time indicates a higher irritation potential. The viability itself is measured by MTT
assay. This assay is also used in the OECD TG 492 and is, thus, a good known colorimetric method for assessing cell vitality and viability. It measures cellular metabolic activity by converting the yellow tetrazolium salt (MTT) into purple formazan crystals in viable cells. The intensity of the purple colour, quantified using a spectrophotometer, correlates with the number of metabolically active cells.15 Figure 2 shows the samples of different shampoos for adults, children and babies as well as the positive and negative controls after different incubation periods. The clear colouring shows that baby shampoos are noticeably milder than shampoo for adults. This clear, measurable approach helps
manufacturers assess how products will perform in real-world applications, especially for those designed for use around the eyes, where even slight irritation can lead to discomfort. The result gives a statement within the irritation classification of minimal/ non-irritating, mild, moderate and severe. In comparison to the results of OECD
TG 492, which is concerned with whether or not a product causes moderate or severe irritation, the ‘No Tears’ test design considers exactly the other half of the scale, and products can be categorised as non-/minimally irritating or mild, or are assessed as irritating (moderate and severe). That means, while the OECD TG 492 categorize a product as non-irritating by excluding damages to the eye, the ‘No Tears’ test design cares about categorizing the non- irritating products according to their mildness. As a result, the ‘No Tears’ test design offers
the possibility of specifically labelling mild and non-/minimally irritating cosmetics. To even generate a possibility to provide end consumers this valuable information, Dermatest has developed the ‘No Tears’ seal for cosmetic manufacturers as a possible labelling option if the test is passed (Figure 3). Dermatest‘s ‘No Tears’ test design and seal,
thus, closes the gap that currently exists and offers a method and tool for valid and reliable labelling of cosmetics and their effect on the eyes.
This gap becomes particularly apparent when the ‘No Tears’ test design is not only directly compared to OECD TG 492 but also to the other previously mentioned methods. This comparison clearly shows that the ‘No Tears’ test design offers many advantages that the other methods can only partially cover. Table 2 summarises the essential evaluation
criteria and results for Dermatest that led to the decision to establish ‘No Tears’ test and not one of the other methods. Even though some of the other methods fulfil some of the criteria, ‘No Tears’ test is the only method that fulfils all criteria with ‘Very good’ and meets Dermatest’s own high scientific quality standards. Thus, unlike traditional methods whose reproducibility is, mainly due to a lack of
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serums. This customization helps ensure that the test accurately reflects how the product will behave in real-world conditions. By adapting the test design to suit different types of products, Dermatest ensures that manufacturers receive the most accurate and meaningful data possible.
Figure 3: Dermatest ‘No Tears’ Seal provided for cosmetic manufacturers as a labeling option if their products can be classified as mild or extra mild
objective data, questionable, Dermatest’s ‘No Tears’ test design provides highly reproducible and quantitative data. This allows companies to make precise formulation adjustments and better compare products. This is especially important for manufacturers who wish to offer products that cater to consumers with sensitive eyes.
The ‘No Tears’ test also complies with
all ethical requirements. By eliminating the need for animal testing, animal derived test models or human trials, the ‘No Tears’ test aligns with global ethical standards and caters to the growing demand for cruelty-free products. It ensures that companies can meet consumer expectations for safety and ethical responsibility. One of the notable strengths of the ‘No
Tears’ test is that it uses tailored exposure models that guarantee the high flexibility of the test design. The test can be customized based on the specific characteristics of the product being tested, ensuring that the exposure models are realistic and relevant. For instance, products containing
surfactants, such as shampoos and facial cleansers, are tested differently from non- surfactant-based products like eye creams or
Conclusion and future directions Sensitivity is a growing concern for many consumers, and the cosmetic industry plays a significant role in either exacerbating or alleviating this issue. The development of testing methods that can accurately assess the irritation potential of products, particularly those designed for use around the eyes, is crucial to ensuring safety and comfort for consumers. The ‘No Tears’ test design established by
Dermatest represents a significant step forward in this regard, offering a more precise, objective and ethical approach to assess the safety of cosmetic products for eyes. By providing quantitative, reliable, and ethically sound data, this testing method helps ensure that products are both safe and effective, giving consumers the peace of mind they need when selecting products for their delicate eye areas. The importance of a tailored test design for
identification of mild and extra mild products becomes even more clear when we consider cosmetic cleansing products. In contrast to products such as eye serums or day creams, that are normally used by adults and where a misleading declaration of the product can cause a temporary discomfort in persons with sensitive eyes, certain cleansing products are regularly also used by babies and small children. However, babies and small children are very
sensitive by nature as their eyes have fewer natural defences to cope with external stressors. Using surfactant-containing products that are not suitable for sensitive eyes can, thus, not only lead to temporary problems like in adults but may lead to long-term damage especially when they get exposed to it regularly.
April 2025 PERSONAL CARE
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