1H-Benzotriazole Round Table

The industrial chemical 1H-benzotriazole is a relevant micropollutant. This means that, even in low concentrations, the substance has adverse effects on aquatic ecosystems and drinking water quality. That is why a round table was launched at the end of 2020 in order to develop mitigation measures.

1H-benzotriazole was classified as a relevant mircopollutant by the “Committee for the Identification of Relevant Micropollutants”. In November 2020, the “1H-Benzotriazole Round Table” was launched with the participation of experts from the Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV), the German Environment Agency (UBA), municipal and Länder environmental agencies, water industry, environmental associations (BBU), Stiftung Warentest and industry. Ten meetings were held.

Benzotriazole is an industrial chemical that has a wide range of applications. Among other things, it is used as corrosion protection for non-ferrous metals in metal processing and in cooling systems and is also incorporated in dishwashing detergents in private (silver protection) and professional areas of application (system protection). The term benzotriazole covers the three benzotriazoles: 1H-benzotriazole (CAS No. 95-14-7), 4-methyl-1H-benzotriazole (CAS No. 29878-31-7) and 5-methyl-1H-benzotriazole (CAS No. 136-85-6). A mixture of the last two compounds is also called tolyltriazole.

During the consultations and the exchange of information and knowledge, a symposium was organised where stakeholders met with other experts to deepen their knowledge of benzotriazole intrusion pathways, sources and sinks.

The round table has been concluded in June 2023 and the final report together with the information document on reducing the discharge of benzotriazole can be found here on the page. In contrast to the round tables on pharmaceuticals (diclofenac and X-ray contrast media), the applications of industrial chemicals are very diverse and must be examined accordingly with regard to their relevance for the aquatic environment. In this respect, the final document provides a good overview of the lines of action pursued by the 1H-benzotriazole Round Table.

* The final report and the information document are the results of the Round Table 1H-benzotriazole and agreed with the participants of the Round Table. Therefore, they do not reflect the opinion of the German Environment Agency and the German Centre for Micropollutants.

Success for the "Round Table 1H-Benzotriazole": Stiftung Warentest evaluates the use of benzotriazole in dishwasher detergents

In the issue Test 8/2023 of the German consumer's magazine "Stiftung Warentest", dishwasher tabs were comprehensively examined. A new evaluation criterion was included in the category "water pollution": The use of triazoles and thus also of the trace substance 1 H-benzotriazole, which is classified as relevant, leads to a maximum rating of 4.0 or "sufficient". This rating also results in a downgrading in the overall quality rating, which may deviate by a maximum of one grade point from the rating in the category "water pollution". Therefore, dishwasher tabs containing the relevant trace substance 1H-benzotriazole as a silver protection agent achieve at best an overall rating of "satisfactory" (grade 3.0).

The silver protection performance of dishwasher tabs continues to be assessed in the category "material protection", since according to research by Stiftung Warentest, more than 10 % of German households clean their silverware in the dishwasher. In addition to a downgrading due to water pollution, there may therefore also be a downgrading of the overall rating due to poor results in silver protection. In general, however, Stiftung Warentest advises against cleaning silver cutlery in the dishwasher.

As the Stiftung Warentest evaluation further shows, the use of 1H-benzotriazole as a silver protection agent is not absolutely necessary. Because products without 1H-benzotriazole perform in part just as well or better in the category "material protection" and show good results in silver protection.

The new approach of Stiftung Warentest in evaluating dishwasher detergents is a positive incentive for manufacturers to adapt their formulations and reduce water pollution. Many formulations already no longer contain 1H-benzotriazole, and a further reduction is to be expected. This development contributes to the goal of reducing the input of 1H-benzotriazole into the environment, which the "Round Table 1H-Benzotriazole" has worked towards.

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 trace substances  micropollutants