Contact allergy caused by methylisothiazolinone and related isothiazolinones
18 april 2017
UAntwerp, Campus Drie Eiken, Building Q, Promotiezaal - Universiteitsplein 1 - 2610 Wilrijk (route: UAntwerpen, Campus Drie Eiken
Prof J. Lambert & Prof A. Goossens
PhD defence Olivier Aerts - Faculty of Medicine and Health Sciences
Isothiazolinone derivatives are synthetic and very efficient preservatives which, owing to their bactericide, fungicide and algaecide properties, are used in cosmetics, household detergents, water-based paints, glues and industrial biocides. The most important derivatives concern: the mixture of methylchloroisothiazolinone and methylisothiazolinone (MCI/MI), MI alone, benzisothiazolinone (BIT), and octylisothiazolinone (OIT). Unfortunately, all these chemicals, MCI/MI and MI in particular, may be the cause of a delayed (type IV, T-cell mediated) hypersensitivity reaction (‘contact allergy’).
This may give rise to ‘allergic contact dermatitis’, which, by means of specific skin tests (‘patch tests’) can be diagnosed. When in 2000 the EU allowed MI (without MCI) as a stand-alone preservative in industrial applications, and in 2005 in cosmetics, problems started to occur: initially occupational dermatitis, in labourers exposed to highly concentrated MI-containing biocides, shortly followed by the first cases of consumers, presenting with allergic contact dermatitis, and sometimes even mucosal and respiratory problems, due to the presence of MI in cosmetics, household detergents, paints, and numerous other products at home or at the workplace. In Europe and beyond an epidemic was born.
This doctoral thesis describes the dramatic sensitization rate to MI in Belgium, the many clinical characteristics of allergic contact dermatitis caused by MI, the most important allergen sources containing MI, the potential cross-reactivity between different isothiazolinone derivatives, the use concentrations of isothiazolinones in cosmetics, detergents, and paints, and the -sometimes incorrect- labelling of the former two products. Finally, we show that OIT is a relevant contact allergen in leather goods for consumers, and we discuss the implications this may have for the study of cross-reactivity between MI and OIT.