Assessment of balsam of Peru patch tests

To find an ideal test technique for as low a dose of balsam of Peru (Myroxy lon Pereirae) as possible, subjects testing positive to balsam of Peru are re-tested with a 25% concentration of balsam of Peru in petrolatum. Applica tions are with Finn Chambers(R) for 6 different application times, and dire ctly by foils for 96 h (4 days (D)). The goals are to confirm which subject s are positive and which are not, and, using that information, to see if it is possible to distinguish between these 2 groups, tested concomitantly at much lower serial dose levels, in terms of perfusion or by visual assessme nts. 5 different serial doses are applied with strips for 3-96 h (4D) and w ith foils for 96 h (4D). The Finn Chamber(R) tests allow a distinction betw een visually positive and negative subjects supported by perfusion assessme nts. With the foils, a 24x lower serial dose level than with the 25% test s ubstance is sufficient to distinguish between positive and negative subject s in terms of perfusion values. This approach requires readings up to 9 day s. With this test, the visual approach yields only 3 of 10 positive subject s. This study demonstrates that a lower test dose is possible with perfusio n assessments compared to visual ones.