Contact sensitization to benzisothiazolinone: IVDK-data of the years 2002 - 2021.

BACKGROUND: Benzisothiazolinone (BIT; CAS No. 2634-33-5) is used as a biocide in various products, including water-based paints, metalworking fluids, and household products. In recent years, increasing sensitization rates have been observed in Europe.

OBJECTIVE: To describe a time trend of sensitization to BIT, analyse concomitant reactions, and identify patients with increased risk of BIT sensitization.

METHODS: Retrospective analysis of data from 26739 patients patch tested with BIT, sodium salt, 0.1% pet. as part of several special test series within the Information Network of Departments of Dermatology (IVDK), 2002-2021.

RESULTS: Positive reactions to BIT were noted in 771 patients (2.9%). Sensitization frequency varied over time and increased in recent years, peaking at 6.5% in 2020. Painters and metalworkers handling metalworking fluids, but not cleaners, had a significantly increased risk of BIT sensitization. From our data, there is no evidence of immunological cross-reactivity between BIT and other isothiazolinones.

CONCLUSION: The increasing frequency of sensitization justifies adding BIT to the baseline series. More research on the clinical relevance of positive patch test reactions to BIT and the cause for the rising numbers of BIT sensitization is needed. This article is protected by copyright. All rights reserved.