Abstract

Colophony is a natural resin produced from pine resin and is made up of a number of resin acids and a neutral fraction. Occupational asthma most commonly occurs when colophony is heated and the fumes inhaled. Most reported cases of colophony asthma have thus been described in electronics workers using flux-cored solder containing a colophony flux; colophony fumes have also caused occupational asthma produced from a hot-melt glue and a depilatory mixture. The resin acids are partially broken
down when heated over 180°C, but colophony heated below this temperature has caused asthma in a chemical worker making colophony derivatives, in workers manufacturing flux-cored solder and in a tool setter exposed to a colophony ester in a soluble oil used as a coolant. Colophony fumes are also a fairly common cause of contact dermatitis. Occupational asthma due to colophony was frequently misdiagnosed as
obstructive bronchitis due to the presence of coughing and sputum and the failure to demonstrate reversible airway obstruction when first seen. In this chapter, methods of diagnosis and symptom patterns are described in groups of workers with colophony asthma; histories of deterioration at work could be confirmed by serial measurements of peak flow at home and work. Bronchial provocation testing in 51 workers showed that colophony fumes were causing specific asthmatic reactions, but could also occasionally act as non-specific irritants in asthmatics with very low PC20 values to histamine.
Epidemiological studies are also described showing that the degree of exposure is the most important determinant for the development of colophony asthma, which is also more common in smokers and in those with positive skin tests to common allergens or a past history of allergic disease. Follow up of affected workers after removal from exposure showed improvement but continuing morbidity. The control of colophony asthma depends on reducing occupational exposures and the introduction of a new assay of colophony fumes.

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