Occupational allergic contact dermatitis caused by wood dusts

Exposure to wood dusts may cause various skin and mucosal symptoms. Allergic dermatoses, caused by wood dusts, diagnosed at the Finnish Institute of Occupational Health during 1976–1999 are reported here. 16 had allergic contact dermatitis and, 2 had contact urticaria. 9 men (3 cabinet makers, 3 joiners, 1 carpenter, 1 knifemaker and 1 machinist) were mainly exposed to tropical hardwoods. 1 man had dermatitis caused by western red cedar. 5 patients, 3 men and 2 women, were exposed to Finnish pine or spruce dusts, and 1 man to aspen. 7 also had rhinitis, 4 asthma or dyspnoea and 3 conjunctivitis. On patch testing, 10 men reacted to 9 different wood dusts, including teak (5), palisander (3), jacaranda (2), mahogany (2), walnut (2) and obeche (1). Reactions to wood allergens, including lapachol (2), deoxylapachol (1), (R)‐3,4‐dimethoxydahlbergione (2), 2,6‐dimethoxy‐1,4‐benzoquinone (1), mansonone A (2) and salicyl alcohol (1), were noted in 4 cases. All but 1 of 5 patients exposed to pine or spruce dusts reacted to the sawdusts, all 5 to colophonium, 3 to abietic acid, 2 to tall oil resin, 3 to wood tar mix and 4 to other wood gum resins. Of the 2 CU patients, 1 was prick and RAST positive to obeche, 1 reacted with urticarial dermatitis to punah wood dust on chamber exposure. Occupational allergic dermatoses are mainly caused by the dusts of hardwoods, mostly due to Type IV allergy, but may also be caused by softwood dusts. Patch tests can be done with wood dusts, but should be confirmed by patch testing with wood allergens if possible.