Colophony--also called
rosin--is a material obtained from coniferous trees. It is used widely in many products, particularly because of its good tackifying properties.
Colophony is also used in paper sizing to increase water resistance.
Colophony may cause contact
allergy, and around 5% of Swedish
dermatitis patients show
allergic reactions to
colophony at patch testing. There are many case reports of
colophony in different products causing
contact dermatitis. Often, however, the clinical relevance of a positive patch-test reaction to
colophony is difficult to evaluate. The principal aims of the present thesis were to study the prevalence of contact
allergy to
colophony and of
skin disease in individuals with an occupational exposure to
colophony; to study the prognosis of
dermatitis in
colophony-sensitive subjects, and to investigate the outcome of repeated open applications of
colophony, thereby trying to elucidate the clinical relevance of contact
allergy to
colophony. Employees of a
tall-oil rosin (
colophony) factory (n = 180), and of an opera company where
colophony was used in dancers'
rosin, mascara and wig
glues (n = 132), were interviewed, examined and patch tested. 3.9% and 2% of these two groups respectively had a positive patch test to
colophony. More than every fourth participant showed some kind of
skin disease, but only few cases were related to work. Eighty-three patients with previously diagnosed contact
allergy to
colophony were followed-up 72% showed a positive patch-test reaction to
colophony at re-testing. Around one third had hand
eczema. There was no significant correlation between
colophony exposure and current hand
eczema. Adhesive bandages containing
colophony and
zinc oxide (ZnO),
colophony and mixes of
colophony and ZnO, were tested in 7
colophony-sensitive subjects to see whether addition of
zinc oxide inhibited elicitation of allergic
dermatitis to
colophony, which has been proposed. No difference in reactivity between
colophony and
colophony/ZnO was seen at patch testing, and there were positive patch-test reactions to all
colophony-containing bandages. Thus no inhibitory effect of ZnO was shown. Repeated open application tests were performed with
cobalt chloride and
colophony in sensitized guinea pigs. The animals were also patch-tested. A dose-response correlation was found with both
cobalt chloride and
colophony. There was a concordance between patch-test reactions and reactions at repeated open application tests, the higher the concentration of the
allergen at the open test the stronger the concordance. In 13
colophony-sensitive subjects serial dilution patch tests with
colophony were performed followed by repeated open application tests using
colophony of different concentrations once daily for two weeks. Reactions were assessed visually, by
laser Doppler flowmetry and by measurements of transepidermal water loss. Ten subjects reacted at open applications with
colophony 20%. The strength of the reaction varied greatly. A correlation between the threshold concentration at patch testing and the outcome of the repeated open application tests was found and also a dose-response relationship. Nine healthy controls did not react to repeated open applications with
colophony. The measurements of transepidermal water loss and bloodflow was of no additional use to visual assessment when evaluating repeated open application test reactions with
colophony.