Discrepancy in patch test results with wool wax alcohols and Amerchol L-101

Wondering why Amerchol L-101 (containing wool wax alcohols obtained from the hydrolysis of wool fat) appears as a test material (100%) in a cosmetics series (Chemotechnique Diagnostics AB), as wool wax alcohols were already tested in the European standard series, we added Amerchol L-101 (100%) systematically to the standard series. From 8 April 1991 to 28 February 1992, a total of 393 patients were tested: 3.05% (n = 12) showed positive test results (+, +2, +3) for wool wax alcohols as well as Amerchol L-101 (100%), 0.3% (n = 1) for wool wax alcohols only, and 11.1% (n = 44) for Amerchol L-101 (100%) only. Thus, the positive tests for Amerchol L-101 (100%) had a higher frequency of 3.4 compared to those for wool wax alcohols. In the meantime, we also added Amerchol L-101 50% (Trolab) to the standard series. Of all patients tested (n = 223) 2.7% (n = 6) had positive reactions to wool wax alcohols and 12.1% (n = 27) to Amerchol L-101 100% and/or 50%. Thus, positive reactions to Amerchol L-101 (100% and 50%) were 4.5 higher, whereas the rate of concordancy decreased. It is remarkable that 8 patients only had a positive reaction to Amerchol L-101 50% and 9 only to Amerchol L-101 100%. It seems that we miss many diagnoses in contact allergy by using only the standard wool wax alcohols test (30%).