Exposure to Wood Dust, Microbial Components, and Terpenes in the Norwegian Sawmill Industry

Abstract

Sawmill workers are exposed to wood dust (a well-known carcinogen), microorganisms, endotoxins, resin acids (diterpenes), and vapours containing terpenes, which may cause skin irritation, allergy, and respiratory symptoms including asthma. The health effects of most of these exposures are poorly understood as most studies measure only wood dust. The present study assessed these exposures in the Norwegian sawmill industry, which processes predominantly spruce and pine. Personal exposures of wood dust, resin acids, endotoxin, fungal spores and fragments, mono-, and sesquiterpenes were measured in 10 departments in 11 saw and planer mills. The geometric mean (GM) and geometric standard deviation (GSD) thoracic exposures were: 0.09 mg m⁻³ dust (GSD 2.6), 3.0 endotoxin units (EU) m⁻³ (GSD 4.9), 0.4 × 10⁵ fungal spores m⁻³ (GSD 4.2), 2 × 10⁵ fungal fragments m⁻³ (GSD 3.2), and 1560 ng m⁻³ of resin acids (GSD 5.5). The GM (GSD) inhalable exposures were: 0.72 mg m⁻³ dust (2.6), 17 EU m⁻³ (4.3), 0.4 × 10⁵ fungal spores m⁻³ (3.8), and 7508 ng m⁻³ (4.4) of resin acids. The overall correlation between the thoracic and inhalable exposure was strong for resin acid (r_p = 0.84), but moderate for all other components (r_p = 0.34–0.64). The GM (GSD) exposure to monoterpenes and sesquiterpenes were 1105 µg m⁻³ (7.8) and 40 µg m⁻³ (3.9), respectively. Although mean exposures were relatively low, the variance was large, with exposures regularly exceeding the recommended occupational exposure limits. The exposures to spores and endotoxins were relatively high in the dry timber departments, but exposures to microbial components and mono-and sesquiterpenes were generally highest in areas where green (undried) timber was handled. Dust and resin acid exposure were highest in the dry areas of the sawmills. Low to moderate correlation between components (r_p ranging from 0.02 to 0.65) suggests that investigations of exposure–response associations for these components (both individually and combined) are feasible in future epidemiological studies.