ABSTRACT
The authors review all aspects of occupational asthma (OA) due to various wood dusts, the first one thoroughly covered being Western red cedar. Most cases of OA caused by wood dusts were published as case reports, with the exception of OA due to Western red cedar (Thuja plicata), which has been studied extensively because it affects a vast number of workers in the primary industries of the west coast of North America and carpenters using this wood in countries where red cedar is exported. Plicatic acid (PA) with a molecular weight of 440 Da, constituting about 90% by weight of the nonvolatile components, has been found to induce Western red cedar asthma. Apart from OA due to Western red cedar, evidence that many other species cause OA mainly originates from case reports and not from proper epidemiological studies. However, many epidemiological studies have confirmed increased prevalence of asthma in sawmills, furniture and cabinet factories, as well as in carpenters. Nasal symptoms are often associated with asthma. In some instances and for a limited number of wood species, an IgE-sensitization mechanism has been identified. An excess frequency of chronic bronchitis and chronic obstructive pulmonary disease (COPD) in workers exposed to wood dusts has also been described in some studies. Other products added to wood dusts for the production of various wood products can also cause OA.
