Work

Development of a Generic Analysis Method for Isothiazolinones in Consumer Products Prompted by Increased Sensitisation to Benzisothiazolinone

Year: 2026

Type: article

Abstract: BACKGROUND: Isothiazolinones are widely used as preservatives in both cosmetic and non-cosmetic products. Sensitisation to isothiazolinones other than chloromethylisothiazolinone/methylisothiazolinone (CMIT/MIT), present in the baseline series, is increasing. OBJECTIVES: To investigate the prevalence of sensitisation to benzisothiazolinone (BIT) in comparison to CMIT/MIT and to develop a product-independent analysis method of isothiazolinones for laboratories with basic instrumentation. PATIENTS AND METHODS: Patch testing with BIT and CMIT/MIT was performed in 803 consecutively tested dermatitis patients. A simple and general analysis method for isothiazolinones was developed for HPLC-UV. RESULTS: Investigation of 14 products labelled to contain BIT and/or CMIT/MIT (cosmetic and non-cosmetic) showed concentrations of BIT in non-cosmetic products of up to 272 ppm. Maximum detected concentrations of CMIT and MIT were 0.3 and 1.5 ppm, respectively. Dichloroctylisothiazolinone and MIT were detected in an unlabelled hobby paint. BIT was a significantly more common cause of sensitisation than CMIT/MIT, at 7.7% and 5.2%, respectively. CONCLUSIONS: Results confirm previous reports indicating that sensitisation to BIT is increasing in dermatitis patients in western Sweden. Analysis of products showed that concentrations of BIT can be several orders of magnitude higher than those of CMIT/MIT in products to which skin contact can be frequent and long lasting.

Source: Contact Dermatitis

DOI: 10.1111/cod.70147