Trends in Benzisothiazolinone Sensitization: A Retrospective Analysis From 2010 to 2022, in a Tertiary Belgian...

Benzisothiazolinone is a preservative responsible for allergic contact dermatitis, with occupational exposure being a common source of sensitisation.

To investigate the prevalence of positive patch test reactions to benzisothiazolinone (BIT) in Belgium, between January 2010 and December 2022, and to assess co-sensitisations to other isothiazolinone derivatives in sensitised patients.

A retrospective monocentric study of patch test results with benzisothiazolinone (BIT) 0.1% petrolatum observed in patients attending a Belgian tertiary hospital. Prevalence, demographic data, concomitant patch test reactions, and clinical relevance were analysed.

Overall, 65 of 6128 patients (1.06%) had a positive patch test reaction to benzisothiazolinone, and its sensitisation rate increased from 0.39% in 2010 to 3.72% in 2019 (followed by a decline to 0.71% in 2022). Occupational exposure was relevant in 20% of cases, with painters and metalworkers being the most affected professions. Unexpectedly, 10.8% of BIT-sensitised patients underwent patch testing due to complications following orthopaedic prosthesis implantation.

This study confirms a significant rise in BIT sensitisation over time, followed by a recent unexplained decline. Occupational exposure remains a major risk factor, but other environmental sources, including consumer products, such as leather products, should not be overlooked. The BIT sensitisation in orthopaedic prosthesis-related complications requires further investigation.