Twenty-two glue sticks, a price ranging from 37 cents to 5.72 euros, and four products in which formaldehyde was found, a substance that the European Union classifies as carcinogenic. This is what emerges from the test conducted by Öko-Test, a German magazine specializing in laboratory analyzes of consumer products, on glues purchased between February and March 2026 in stationery shops, discount stores, supermarkets and online shops. The striking data is not so much the presence of the substance, but the variability: in one of the products tested the formaldehyde – a substance classified as a category 1B carcinogen by the EU – slightly exceeds the threshold value adopted by the researchers, in another (Tedi glue, sold in a double pack for 50 cents) the quantity detected is more than twenty times higher.
Because the reference limit is that of toys
Here a regulatory issue arises that Öko-Test clearly points out: in the European Union there is no specific regulation for the ingredients of glue sticks or glues for crafts. The researchers then applied, by analogy, the limits set by the European Toy Directive (2009/48/EC) for water-based materials intended for children under three years of age, an approach also shared by the Regional Analysis Office of Rhineland-Palatinate. The logic is simple: none of the 22 glues tested reported a minimum age of use, so the evaluation was conducted with the most vulnerable group in mind. This is no small detail, if you think about how children actually use these products: their faces bent over the paper, their hands dirty with glue which then end up in their eyes or mouths before even being washed.
Preservatives and caprolactam: the other problems detected
Formaldehyde is not the only critical issue, given that around a third of the products tested contain isothiazolinones, preservatives with a certified sensitizing power: the laboratory detected benzisothiazolinone (BIT) in seven glues, and in one of these also methylisothiazolinone (MIT). To complete the picture there is caprolactam, a substance classified by European legislation as irritating to the skin and eyes and harmful if ingested, identified in some of the products analyzed with concentrations above 1,000 mg/kg.
The practical test: it holds almost everything well, except two products
The laboratory did not stop at the chemical composition, also carrying out a sort of practical test: it glued two sheets of paper folded several times, left them to dry under pressure for a quarter of an hour, then measured the force needed to detach them with a dynamometer. The result saw most glues hold up well or very well to the test, only two products disappointed. In the end, out of 22 glue sticks tested, ten obtained the “very good” rating (among these included brands such as BIC, Pelikan, Uhu and Edeka) while four were rejected with “insufficient” due to the presence of formaldehyde. Among the brands involved, in addition to the aforementioned Tedi, are Paperzone Black Glue Stick (sold by Müller, with the words “non-toxic” on the label) and Stenzer glue distributed by Woolworth.
