Rosin

Originally, rosin was produced almost exclusively from turpentine (see turpentine oil purified below). Increasingly, increasing quantities of rosin are obtained by using resins extracted from roots or as a by-product of sulphate pulp cooking.

Rosin is a natural product made from the resin of conifers (especially pine species). Depending on the geographical origin of the woods used as raw material, rosin contains different concentrations of abietic acid, neoabietic acid, laevoabietic acid, pimaric acid, isopimaric acid and palustric acid. Of lesser importance are protocatechuic acid (3,4-dihydroxy-benzoic acid), bitter substances, ethers and lactones.

Combinations of the individual ingredients can be effective as contact allergens.

Evaluation of colophony with regard to the effect of allergy on the reduction of earning capacity:

In relation to the very wide distribution of colophony, occupational allergic contact eczema is not as frequent and extra-occupational contact possibilities are equally important.

Relevant occupational exposures: Natural rosin and its modifications are widely used in adhesives in industry and in the private sector, e.g. in wound plasters, in paints, varnishes and printing inks, in gums, in cosmetics, in chewing gum, depilatory waxes, tree guards and dental waxes, and as slip inhibitors (e.g. as violin resin, in sports and dancing). It is used as a flux for soft soldering. Rosin is contained in softwoods and products made from them (furniture, chipboard, paper and cardboard). Cases of occupational diseases caused by rosin have been registered in the following occupational groups:

• Chemical plant workers, plastics workers, bookbinders, printers/printing assistants, moulders and formers, solderers, metal-cutting metalworkers, metalworkers, electricians/fitters, carpenters and other woodworking trades, painters, hairdressers, health professionals.

Effect of an allergy: "Low" in an isolated sensitization to a modified resin without group reaction and with limited use. "Moderate" when the workplaces of the above mentioned professions are considered closed. It must always be checked whether rosin-free substitutes can be used and thus changes of activity avoided (distinction between "low-grade" and "medium-grade"). "Serious" if the trigger threshold for the allergy is so low that contact with common types of paper also causes contact eczema.

1. Cockayne SE et al (2001) Occupational contact dermatitis from colophony in a dental technician. Contact Dermatitis 44: 42-43
2. Diepgen TL et al. (2005) Evidence-based assessment of the effect of type IV allergies in the reduction of earning capacity - assessment of occupational skin diseases. Dermatologist 56: 207-223
3. Diepgen TL et al (2002) Assessment of the effect of allergies in the reduction of earning capacity in the context of BK 5101 Part I: Acrylates/methacrylates, epoxy resin systems, formaldehyde, dichromate, rosin, latex, nickel, p-phenylenediamine. Dermatol Occupation Environment 50: 139-154
4. Kanerva L et al (2001) Colophony in sanitary pads. Contact Dermatitis 44: 59-60
5. Krakowiak A et al (2004) Occupational contact dermatitis with rhinoconjunctivitis due to Tilia cordata and colophony exposure in a cosmetician. Contact dermatitis 51: 34
6. Kuner N et al (2004) Allergic contact dermatitis from colophony, turpentine and ebony in a violinist presenting as fiddler's neck. Contact Dermatitis 50: 258-529
7. Li LF et al (2002) Contact hypersensitivity in hand dermatitis. Contact dermatitis 47: 206-209
8. Strauss RM, Wilkinson SM (2002) Shoe dermatitis due to colophony used as leather tanning or finishing agent in Portuguese shoes. Contact Dermatitis 47: 59