Purpose: The aim of the study is to investigate risk factors for sensitization to preservatives and to examine to which extent different preservatives are registered in chemical products for occupational use in Denmark.
Methods: A retrospective epidemiological observational analysis of data from a university hospital was conducted. All patients had occupational contact dermatitis and were consecutively patch tested with 11 preservatives from the European baseline series and extended patch test series during a 5-year period: 2009-2013. Information regarding the same preservatives in chemical products for occupational use ('substances and materials') registered in the Danish Product Register Database (PROBAS) was obtained.
Results: The frequency of preservative contact allergy was 14.2% (n = 141) in 995 patients with occupational contact dermatitis. Patients with preservative contact allergy had significantly more frequently facial dermatitis (19.9 versus 13.1%) and age > 40 years (71.6 versus 45.8%) than patients without preservative contact allergy, whereas atopic dermatitis was less frequently observed (12.1 versus 19.8%). Preservative contact allergy was more frequent in painters with occupational contact dermatitis as compared to non-painters with occupational contact dermatitis (p < 0.001). This was mainly caused by contact allergy to methylisothiazolinone and contact allergy to formaldehyde. Analysis of the registered substances and materials in PROBAS revealed that preservatives occurred in several product categories, e.g., 'paints and varnishes', 'cleaning agents', 'cooling agents', and 'polishing agents'. Formaldehyde and isothiazolinones were extensively registered in PROBAS.
Conclusions: The extensive use of formaldehyde and isothiazolinones in chemical products for occupational use may be problematic for the worker. Appropriate legislation, substitution, and employee education should be prioritized.
Keywords: Chemical products; Exposure; Formaldehyde; Methylisothiazolinone; Occupational contact dermatitis; Preservatives.