Nickel and cobalt: Underestimated contact allergens in hairdressers?

Introduction: Nickel and cobalt were not regarded as pertinent contact allergens in the hairdressing trade for the last decades. It was even stated that the relevance of nickel allergy in the hairdressing trade has been overestimated for several years. Recently, nickel and cobalt release from a multitude of metal tools in the German hairdressing trade was documented in two field studies. Methods: Review of two field studies. Results: In 2019, nickel release from 9.2% of 229 tested metallic hairdressing tools was evidenced, and in 2021, nickel release from 27.6% as well as cobalt release from 2.1% of 475 tested tools was detected in overall 30 North German hairdressing salons. Tweezers, sectioning clips, hair clips, and straight razors were identified as nickel as well as cobalt releasing tools. Crochet hooks and tail combs were identified as only nickel releasing tools. Discussion: A variety of metallic tools – which are used daily by hairdressers – release nickel and/or cobalt in allergologically relevant amounts. This circumstance has to be considered problematic with regard to the development of work-related allergic contact dermatitis. Thus, nickel and cobalt should possibly receive greater attention as potential contact allergens in the hairdressing trade. Conclusion: The proven nickel and cobalt release from metallic hairdressing tools might entail legal ramifications in terms of insurance law. In case of nickel and cobalt allergies within the occupational group of hairdressers, metal tools might be considered as feasible sources for nickel and cobalt exposure.