Isothiazolinones in cleaning products: Analysis with liquid chromatography tandem mass spectrometry of samples from sensitized patients and market.

Background: Methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) contact dermatitis is a severe problem. The high concentrations of these substances and other isothiazolinones such as benzisothiazolinone (BIT) and octylisothiazolinone (OIT) contained in cleaning products may cause allergic contact dermatitis in sensitized patients.

Objectives: To evaluate the exposure to isothiazolinones contained in cleaning products on the market and from sensitized patients, and to verify the accuracy of labeling.

Methods: A total of 34 cleaning products were collected (17 supplied by sensitized patients and 17 bought randomly). Analysis was made of the concentrations of MI, MCI, BIT, and OIT using liquid chromatography tandem mass spectrometry (LC-MS/MS).

Results: MI and BIT were the components most frequently detected. Of all the products analyzed, 76.5% contained at least one isothiazolinone. Twelve products had an MI concentration above the permitted level for rinse-off cosmetics. Most of them were coming into direct contact with the skin in daily use. Mislabeling occurred in eight products.

Conclusions: Some cleaning products with high concentrations of isothiazolinones may cause cutaneous symptoms in sensitized patients, especially in spray form. The labeling should be correct, also regarding the use of each article.