Abstract
Contact allergy (sensitisation) and allergic contact dermatitis (ACD) resulting from it have a considerable public health impact. For the present review, all pertinent articles were systematically searched via Medline and Web of Science™; additionally, all available issues of the journals “Contact Dermatitis” and “Dermatitis” were manually searched, covering the years 2018–2019, thereby extending and re-focusing a previous similar review. New allergens, or previously described allergens found in a new exposure context or of other current importance, are described in sections according to substance classes, e.g., metals, preservatives, fragrances. As a common finding in many investigations, a lack of information on product composition has been noted, for instance, regarding a newly described allergen in canvas shoes (dimethylthiocarbamylbenzothiazole sulfide) and, most notably, absence of co-operation from manufacturers of glucose-monitoring devices and insulin pumps, respectively. These latter devices have been shown to cause severe ACD in a considerable number of diabetic patients caused by the liberation of isobornyl acrylate and N,N’-dimethylacrylamide, respectively, as demonstrated by an international collaboration between dermatologists and chemists. Improved and complete ingredient labelling for all types of products, and not just as we have with cosmetics at present (apart from full listing of fragrance substances) in Europe, must be put on the legislative agenda.
Highlights
Contact allergy is an acquired immunological alteration caused by skin, or occasional mucosal or systemic, contact to low molecular weight substances
The categorisation is according to the nature of the allergen and not the context where it has been found, the only exception being allergens found in medical devices owing to the prominent role of this problem
An identified sensitisation hazard will trigger labelling and hazard warnings according to the Globally Harmonized System (GHS), implemented in the EU as Classification, Labelling and Packaging Regulation EU Chemicals Regulation (EC) 1272/2008; the criteria used for this purpose have been discussed recently [342]
Summary
Contact allergy is an acquired immunological alteration caused by skin, or occasional mucosal or systemic, contact to (generally) low molecular weight substances. Despite considerable efforts, it remains largely unclear and unpredictable as to who will, under the same conditions of exposure, develop contact allergy and who will not. Some driving forces of acquisition of contact allergy are well known: (i) the hazard in terms of the sensitising potency of a substance,. (ii) exposure conditions regarding dose/area, repeated and/or aggregated exposure to the substance resulting in sensitisation risk, and (iii) general susceptibility factors such as a compromised epidermal barrier, prevailing cutaneous inflammation, as well as the yet unidentified individual predisposing (susceptibility) factors. Public Health 2020, 17, 2404; doi:10.3390/ijerph17072404 www.mdpi.com/journal/ijerph
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