In 1990 Danish nickel (Ni) regulations limited Ni release from consumer products to 0.5 ug/cm2/week or less. Two cross-sectional studies, one conducted in 1990 and one in 2006, compared the prevalence of concomitant Ni contact allergy and hand eczema in 3,881 recipients (aged 18-69 years) of a postal questionnaire. Participants were also patch tested for Ni contact allergy. In 18-35-year-old females, the prevalence of Ni allergy and a history of hand eczema decreased from 9% in 1990 to 2.1% in 2006 (P < 0.01). The odds ratios also decreased from 3.63 to 0.65 in this group. There were no significant correlations with Ni allergy and hand eczema in older women or ...