Metal allergy in north Norwegian schoolchildren and its relationship with ear piercing and atopy.

In 424 schoolchildren (223 boys and 201 girls) aged 7-12 years undergoing routine patch tests, 21.0% (89 children), 38.8% (78/201) of girls and 4.9% (11/223) of boys, had had their ears pierced. 18.6% (79 children, 55 girls and 24 boys) gave a history of cutaneous reactions to metallic jewelry, and in 17.2% (73 children, 49 girls and 24 boys), sensitivity to one or more metals was confirmed. Metal allergy was confirmed by patch testing in only 34.2% of the children with a history of metal dermatitis, and 13.3% of those without a history of metal reactions had, in fact, positive patch tests to 1 or more metals. The low sensitivity (37.0%) and low positive predictive value (34.2%), together with high specificity (85.2%) and high negative predictive value (86.7%), seem to justify dermatological examination of individuals with a positive symptom-based diagnosis only. Nickel sensitivity was found in 14.9% (63 children, 44 girls and 19 boys). There is clearly a relationship between ear piercing and induction of nickel allergy in girls, as nickel sensitivity in girls with pierced ears was 2x (30.8%) that found in those without (16.3%) pierced ears. In boys, nickel sensitivity was much less frequent and few cases were related to ear piercing. Atopy appeared to influence the propensity for developing metal sensitivity in girls, as atopic girls showed positive metal tests 2x as frequently (30.8%) as non-atopic (17.0%).(ABSTRACT TRUNCATED AT 250 WORDS)