A woman in her 40s with increasing facial dermatitis. The dermatitis appeared while her home was being redecorated, and several rooms were painted with water-based paint. Over the past four years she has had several episodes of facial eczema. In at least two of the cases, she suspected a reaction to suntan lotion.
Epicutaneous testing revealed a strong allergic reaction to the preservatives methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI). She showed no reaction to epicutaneous testing with sunscreen allergens. A user test was not carried out. The dermatitis gradually disappeared after the painting was completed and she stopped using cosmetics at the same time.
The preservatives in question are used in skin products, cleaning and polishing agents and water-based paint. The chlorine compound, methylchloroisothiazolinone, is the strongest allergen (1, 2). The combination methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) was formerly used as a preservative in skin creams, but MI has been used more frequently since 2005 (1, 2). Since then, the incidence of allergy to MI has been shown to be on the increase in a number of European countries (2). Relatively high concentrations of MCI/MI are still to be found in shampoos and cleaning agents (3). Water-based paint is often preserved with these products, but in lower concentrations (1).
Our patient had probably become sensitised as a result of using skincare products containing MCI/MI. Contact allergy eczema has subsequently occurred as a result of direct skin contact (skincare creams, shampoos) and now by airborne contact (paint fumes). The latter type of reaction has been described for several allergens, including MCI/MI, and must be considered when patients present with this type of facial dermatitis. The concentration of MCI/MI in the air in newly painted rooms is so low, however, that only previously sensitised persons are likely to develop eczema.