Four cases of allergic contact dermatitis caused by methylchloroisothiazolinone/methylisothiazolinone in ironing water

Methylisothiazolinone (MI) (CAS no. 2682-20-4) and methylchloroisothiazolinone (MCI) (CAS no. 26172-55-4) have been widely used as preservatives in cosmetics, household products and industrial products since the late 1970s. The first cases of contact allergy to the MCI/MI combination were noted in 1980 (1). Ironing water is being increasing used as a product designed to making ironing more enjoyable. The role of ironing water is to bring a fresh, outdoorsy fragrance to the ironing process; it is also claimed that these products smooth away creases, and protect the iron from limescale. We report four cases of allergic contact dermatitis caused by MCI/MI found in ironing water, an usual source of exposure. There has been only a single previous case report in the literature (2).