Methylisothiazolinone or MIT is mainly used for its preservative properties, particularly in paints and coatings, detergents, industrial processes, cosmetic products, etc. A recent study detected the presence of MIT in 93% of the paints tested. MIT can also be used for its fungicidal, bactericidal and disinfectant properties in a wide number of applications: varnishes, adhesives, detergents, textiles, etc.
Over the last few years, in France and elsewhere in Europe, many publications have highlighted an alarming increase in the number of cases of skin allergies to this substance.
In toxicological terms, MIT is recognised as a skin sensitiser, based on experimental data in animals and humans. Accordingly, following exposure to a high concentration of MIT, mainly via cosmetics, an allergic skin reaction may occur on re-exposure, even to low concentrations.
In addition, the presence of MIT at high concentrations in many products for professional use is a cause of severe contact dermatitis in many professional categories.
In this context, ANSES issued an internal request to conduct a review of the uses of MIT and describe the associated risks of dermal and respiratory sensitisation. The aim was to identify the categories of products entailing the most exposure, with a view to proposing possible recommendations to limit the exposure of people, whether or not they are already sensitised.
The Agency’s recommendations
In January 2015, a dossier for harmonised classification was submitted by Slovenia at European level in the framework of the "CLP" Regulation (on the classification, labelling and packaging of substances). This dossier proposes to classify MIT as a Category 1 skin sensitiser with a specific concentration limit of 0.06% (600 ppm). During the public consultation phase for this proposal, France indicated that it considered this limit of 600 ppm much too high in light of the available data and proposed a limit of 15 ppm. Other comments from European public institutions or Member States also support this view and propose a concentration limit offering greater protection. This proposal for classification is to be discussed shortly with all the Member States.
The Agency also believes it is necessary to continue discussions at European level in the framework of the "Cosmetics" Regulation, in order to modify the concentrations of MIT as a preservative in cosmetic products.
The Agency recommends that information intended for the general population and professionals be systematically provided on the packaging of mixtures containing MIT, regardless of the level of concentration in the mixture. This information is already mandatory for cosmetics and detergents. Providing, from the lowest concentration applicable, systematic information to the finished product as placed on the market, will enable sensitised individuals to avoid contact with the allergen.
Moreover, as part of its work on the question of emissions of pollutants from construction materials, in 2009 ANSES had proposed a procedure for the qualification of volatile organic compound emissions. A lowest concentration of interest (LCI) had then been determined for MIT. This French value was also adopted by the European working group for the harmonisation of protocols and LCIs. In light of recent data, the Agency recommends taking MIT into account in the labelling specified for construction products, in order to inform consumers and workers about the emission levels of volatile pollutants.
Lastly, the Agency is continuing its work on the analysis of occupational dermatitis in the framework of the National Network for Monitoring and Prevention of Occupational Diseases (RNV3P), which it coordinates. These studies will help describe the prevalence of these skin disorders according to the hazard, and identify the sectors or jobs at risk with a view to making recommendations for the implementation of appropriate preventive and protection measures in the workplace.