Contact allergy to colophony

Abstract
The sensitizing capacity of 15 commercial colophony products was studied experimentally in guinea pigs. The study included 8 French and 6 American colophony derivatives as well as French tall oil colophony. The results indicate that tall oil colophony is the strongest sensitizing material within the tested group and that the maleic-modified product and the zinc-calcium-resinate are moderate sensitizers. Most of the modified products show a higher sensitizing capacity than the genuine resin acids themselves. Cross-reactions between the resin acids and the derivatives are uncommon. Therefore, patch testing with high concentrations of colophony (e.g., 60%) will not help to detect patients with colophony-derivative allergy.