Colophony, a hidden allergen on ECG electrodes in a boy after cardiovascular surgery.

We report on the first case identifying colophony as a hidden allergen in declared acrylate-based conductive and adhesive foam electrodes. This surgery was followed by continuous electrocardiogram monitoring. The patch tests showed strong positive reactions to colophony. The presence of colophony on the electrocardiogram electrodes was not declared, but it was used in the soldering process during manufacture, which deposited a small amount that was sufficient to induce sensitization.