Quaternium-15 sensitization in the north-east of Italy, trend from 1996 to 2016 and occupational role

Methenamine 3-chloroallylochloride (CAS 51229-78-8) or quaternium-15 is a quaternary ammonium salt that was used as preservative in many cosmetics, liquid soaps, moisturizers, eye make-up, bath gels, shaving creams and cleaning supplies (also non-cosmetic supplies, as floor waxes and inks).1–3 It is a formaldehyde releaser with a broad-spectrum antimicrobial and antifungal action that has been recently prohibited in cosmetics by the Commission Regulation (EU) 2019/831 of 22 May 2019. It is known from several studies that quaternium-15 can cause contact allergy,3–6 and the sensitization trend was studied in other countries, but there are no available data as far as Italy is concerned.