Contact dermatitis: etiologies of the allergic and irritant type.

The term contact dermatitis describes an inflammatory process of the skin that occurs in response to contact with exogenous substances and involves pruritic and erythematous patches. Approximately 80% of all contact dermatitis is primary irritant contact dermatitis (ICD), whereas allergic contact dermatitis (ACD) makes up only 20% of contact dermatitis cases, the estimated prevalence of contact dermatitis in the United States being 1.4%. Among patch-tested patients, nickel has been identified as the most common allergen. Cobalt is the second most common metal allergen and is found in various dental alloys, paints, and coloring components of porcelain and glass. The average prevalence of dermatitis due to p-phenylenediamine (PPD) was found to be 4.3% in Asia, 4.0% in Europe, and 6.2% in North America. Rubber gloves are a major cause of occupational ACD in healthcare workers. Occupations involving frequent handwashing, between 20 and 40 times per day, have shown an increased incidence in cumulative ICD. The prevalence of occupational hand dermatitis was 69.7% in workers that reported a handwashing frequency exceeding 35 times per shift. The use of alcohol-based sanitizers is much more prevalent among today's healthcare workers than frequent handwashing. Both allergic and ICD are worldwide problems.