The prevalence of
metal allergy is high in the general population, and it is estimated that up to 17% of women and 3% of men are allergic to
nickel and that 1-3% are allergic to
cobalt and
chromium. Among
dermatitis patients, the prevalence of
metal allergy is even higher.
Metal allergy is mainly an environmental disorder although null mutations in the
filaggrin gene complex were recently found to be associated with
nickel allergy and
dermatitis. Environmental
metal exposures include jewelry, buttons, clothing fasteners, dental restorations, mobile phones, and leather. Although consumer exposure is responsible for most cases of
metal allergy, the importance of occupational
metal exposure remains present and should always be taken into consideration when one interprets allergic patch test reactions to metals. Traditionally,
nickel,
cobalt, and
chromium have been the most important contact
allergens. However, recently,
gold and
palladium have drawn much attention as the prevalence of contact
allergy to these metals is high.
Palladium allergy is mainly a result of cross-sensitization to
nickel, whereas
gold allergy is rarely clinically relevant when one takes its high prevalence into account. The epidemiology of
metal allergy has recently changed in Europe as
nickel allergy among ear-pierced Danish women has decreased following regulatory intervention on
nickel release from consumer products. In the United States, the prevalence of
nickel allergy is still increasing, which may be explained by the absence of regulation. The prevalence of
chromium allergy is increasing in the United States, Singapore, and Denmark among
dermatitis patients. This increase is significantly associated with leather exposure in Denmark.
Metal allergy may result in
allergic contact dermatitis and systemic
allergic (contact) dermatitis. Furthermore,
metal allergy has been associated with device failure following insertion of intracoronary
stents, hip and
knee prostheses, as well as other implants. This area is in need of more research.