Methylisothiazolinones. Diagnosis and prevention of allergic contact dermatitis

Sammanfattning: Preservatives are biologically active substances which are required in water-based products/systems to prevent growth of micro-organisms. Kathon® CG (K-CG), one of several preservatives based on 5-chloro-2-methyl-4-isothiazolinon-3-one (MCI) and 2-methyl-4-isothiazolin-3-one (MI) has been shown to be a common sensitizer in dermatitis patients. The aims of the study were to find a method to demonstrate and quantify MCI and MI in various products; to isolate and identify the contact allergens in K-CG; to assess the sensitizing capacities of the allergens; to study the actual occurrence of MCI and MI in moisturizers; to investigate the occurrence and causes of occupational dermatoses in a plant where high concentrations of MCI and MI are handled; to find methods to prevent chemical burns and allergic contact dermatitis from MCI and MI. MCI and MI were demonstrated in various types of products by HPLC. Three allergens were isolated from K-CG and identified as MCI, MI and 4,5-dichloro-2-methyl-4-isothiazolin-3-one (45243-K-CG). Guinea pig maximization tests showed that MCI and 45243-K-CG were strong sensitizers and MI a weak sensitizer. At a plant where high concentrations of MCI and MI were used to produce binders and glues 9 of 51 present production workers (17.6 %) were sensitized to MCI and MI. Four of the 9 MCI- and MI-sensitized workers had spilled preservatives with high concentrations of MCI and MI on their skin resulting in chemical burns. Sodium bisulfite and glutathione were demonstrated to chemically inactivate MCI and MI.