Persistence of Isothiazolinones in Clothes After Machine Washing

Background Sensitization to methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) is a worldwide problem. Washing machine detergents are suspected to cause cutaneous symptoms in highly sensitized patients. Little is known about the persistence of isothiazolinones in clothes that have been washed. Objective The aim of the study was to analyze the possible persistence of MI, MCI, benzisothiazolinone, and octylisothiazolinone in common fabrics after machine washing. Methods Different clothes (cotton, polyester, linen, and wool) were collected, and 4 types of wash were done (control, standard, standard + conditioner, and standard + double rinse). The samples were analyzed using ultrahigh-performance liquid chromatography. Results The results showed that the concentrations of isothiazolinones were very low, independent of the type of material or wash. The highest levels were found in the control wash (hand wash), reaching a maximum of 0.4 ppm in the linen. Conclusions Our findings suggest that it is not necessary to recommend that patients sensitized to MI avoid isothiazolinones in machine detergents or fabric conditioners or to double rinse. However, after using the detergent for hand washing (the control in our study), there may remain sufficient concentrations of isothiazolinones in clothes to produce symptoms in highly sensitized patients.