Allergic contact sensitisation, causing allergic contact dermatitis, is a health issue in the private as well as in the occupational context. The aim of the present study is to give an overview of frequencies of sensitisation to specific substances and in specific occupational groups including patients with and without occupational dermatitis (OD). Putting this data in relation to the number of employees may lead to indications of a need for regulation.

Based on data of the Information Network of Departments of Dermatology (IVDK) of the years 2007 to 2016 (120,977 patients), an overview of all patch tested allergens which elicited positive reactions is provided, including reaction frequencies and interpretation aids for all allergens and patch test preparations. Sensitisation frequencies in OD patients and non-OD patients are compared. Incident rates of contact sensitisation to specific allergens in specific occupational groups are calculated based on data taken from the IVDK, the German Statutory Accident Insurance (Deutsche Gesetzliche Unfallversicherung; DGUV), and the German Federal Employment Agency (Bundesagentur für Arbeit; BA Arbeit) for the years 2013-2015. The incident rates are expressed as cases per 100,000 workers per year.

In total, positive test reactions were observed to 420 allergen preparations. Despite a decrease in nickel sensitisation as a result of EU regulations, nickel still remains the most frequent contact sensitiser, due to its widespread use, in particular in costum jewellery. Beyond nickel, cobalt and chromate, fragrances and preservatives are among the most frequent contact sensitisers. As a consequence of increasing use as preservative in cosmetics, contact sensitisation to methylisothiazolinone (MI) has heavily increased all over Europe.The largest groups of patients with occupational dermatitis registered in the IVDK are health care professionals (12.3%), mechanics (11.1%), hairdressers (6.2%), cleaners (4.7%), geriatric nurses (4.4%), metal workers (3.8%), cooks (3.7%), and construction workers (2.8%). Allergic reactions to metals such as nickel, cobalt and chromate, to preservatives such as methylchloroisothiazolinone / methylisothiazolinone (MCI/MI), thiurams, mercaptobenzothiazole derivatives, and dithiocarbamates (three groups of rubber ingredients), colophony, and epoxy resin occurred more frequently among OD patients than among non-OD patients, whereas allergic reactions to fragrance patch test preparations were observed more frequently among non-OD patients. Nevertheless, occupational groups such as geriatric nurses and health care professionals were for example, over-represented among OD patients who reacted to fragrance mix I and fragrance mix II as compared to OD patients who were not sensitised to the respective allergen preparation.

The highest incident rate of contact sensitisation per 100,000 workers per year in each selected occupational group ranges from < 1 for colophony in office clerks to > 100 for
several allergens in ‘airdressers, barbers, beauticians, wigmakers’ The reasons for the very probable overestimation in the case of hairdressers are discussed in detail.