Incidence and prevalence of occupational contact dermatitis in hairdressing apprentices: A 3-year prospective cohort study

Background: It is known that a large number of hairdressing apprentices (HA) develop occupational contact dermatitis (OCD) during schooling, but studies that address prevalence of contact sensitization in HAs with hand eczema are missing. Objectives: To assess the prevalence, incidence rate and clinical characteristics of OCD, including contact sensitization, in a sample of Croatian HAs. Materials and Methods: A total of 408 HAs from 25 Croatian towns were examined at the beginning of education and monitored at the end of each school year. Clinical evaluation of skin changes was performed using the Osnabrueck Hand Eczema Severity Index (OHSI). Standard patch test (PT) with baseline and hairdresser series of contact allergens was performed in 46 HAs with skin changes lasting >= 3 months. Results: The overall incidence rate of OCD was 32.3/100 person-years, and the 3-year prevalence 50.3%. Contact sensitization was found in 14 out of 46 (30.3%) HAs, with 10 of these 14 HAs (71.4%) sensitized to specific hairdressing allergens. The strongest reactions were found to PPD. HAs with positive PT had higher OHSI than HAs with negative patch test (median, IQR: 3, 2-4 vs. 2, 2-4). Conclusions: Contact sensitization to specific hairdressing chemicals was found in 71.4% of HAs with a positive patch test, supporting evidence on the early contact sensitization to occupational allergens among HAs.