Kathon CG and Kathon WT are biocides containing 5-Chloro-2-Methyl-4-Isothiazoline-3-One (MCI) and 2-Methyl-4-Isothiazoline-3-One (MI) in a 3:1 ratio. These compounds are used as preservatives in skin care products and there have been many reports of allergic contact dermatitis due to Kathon used in this context. They are also widely used in industry as preservatives in metal working fluids, latex emulsions and for water treatment. Two cases of severe irritant contact dermatitis through accidental exposure to high concentrations of Kathon in industrial settings are reported to highlight the importance of worker education and the use of personal protective equipment when handling this corrosive chemical.