Does sensitization to contact allergens begin in infancy?

Objective. Because previous studies have found allergic contact sensitization common in children by 5 years of age, our aim was to determine the prevalence of positive epicutaneous test results in children <5 years of age and to determine whether sensitization to contact allergens was as common in infancy. Methods. We recruited 95 asymptomatic children 6 months to 5 years of age from well-child visits at Denver area pediatric practices for epicutaneous patch testing using the T.R.U.E. Test system. Allergens were placed on the skin for 48 hours, and at a later follow-up visit, positive reactions were evaluated. Results. A total of 85 patients completed the study. Of these, 20 (24.5%) had 1 or more positive reactions to the tested allergens. Positive reactors ranged from 6 to 65.5 months of age, with an average of 30.4 months of age. Of the children, 16 reacted to 1 allergen, and 4 reacted to 2. Eleven positive reactions were observed to nickel, followed by 8 to thimerosal. Other positive reactions were to neomycin, cobalt, and kathon CG. Conclusions. Children as young as 6 months of age may be sensitized to contact allergens. Within this pediatric population, the prevalence of sensitization is 24.5%. Sensitization to contact allergens may occur in infants.