Exposure to wood dust is associated with an increased risk of nasal carcinoma and other allergic, respiratory and dermatologic health conditions. This study developed and assessed the effectiveness of an intervention to reduce wood dust by 30% in small businesses that manufacture cabinets, fixtures or furniture. The study had three primary aims: (1) To measure mean wood dust exposures in small wood working businesses (320) employees and to assess the level of dust controls (engineering, administrative, and behavioral) as measured by a walk-through survey; (2) To determine if an efficient industrial hygiene intervention program can be implemented in small wood working shops; and (3) To assess the effectiveness of this industrial hygiene intervention by a standard public health strategy in a randomized controlled trial. During the first year of the study, a pilot study was conducted to develop sampling and intervention methodology. Following this pilot study, 48 woodworking businesses (5-25 employees) were randomly assigned to intervention or comparison condition. The intervention consisted of written recommendations, technical assistance to enhance engineering and administrative methods and worker training, tailored to the needs of the business. Comparison businesses received written recommendations alone. Changes from baseline in dust concentration (via personal sampling ofinhalable dust), availability, use and efficiency of dust control methods (via direct observation), and worker knowledge, attitudes and behavior (via questionnaire) were assessed in both groups one year later. Baseline characteristics were similar for both groups. Workers in intervention businesses were more likely than those in comparison businesses to report at follow-up that they were informed about dust control (mean intervention effect= 0.25, 95% CI = 0.03, 0.46), to show an increase in stage of readiness to control dust (mean intervention effect = 0.43, 95% CI = 0.08-0.77) and to change work behavior consistent with reducing dust (mean intervention effect =0.12,95% CI = -0.01,0.25). However, the log mean dust concentration was only 0.11 mg/m3 lower among intervention businesses versus comparison businesses (95% CI = -0.34, 0.12), a difference of about 6%, and other environmental changes related to dust control were similarly minimal. To properly design controls such as this, it is important to understand the activities which produce dust, the nature of exposures, and the knowledge, attitudes and beliefs held by workers and owners toward wood dust and its health effects. To gather this information, the study team made use of a planning committee, worker/owner focus groups, and a pilot study in five woodworking shops. The planning committee consisted of representatives from small woodworking shops, a local industry association, state agencies, a local technical college, a large wood products manufacturer, and a local supplier. These individuals were instrumental in providing input on written materials, plans for technical and educational interventions, and ideas for gaining access to shops. This study is one of the few conducted in the occupational setting to date that employed a rigorous design with adequate sample size, was multidisciplinary, and utilized multiple methods of data collection. The failure of the intervention to reduce wood dust may be attributed more to the complex challenge of conducting intervention effectiveness research in the occupational setting, than to the intervention per se.
Minnesota Department of Health, Chronic Disease and Environmental Epidemiology Section, 717 Delaware Street Southeast, P.O. Box 9441, Minneapolis, MN 55440-9441
Minnesota Department of Health, Chronic Disease and Environmental Epidemiology Section, Minneapolis, Minnesota