A meta-analysis on wood dust exposure and risk of asthma.

Work-related asthma is the most common occupational respiratory disorder in the industrialized countries. It has been postulated that wood dust exposure may increase the risk of work-related asthma. The objective of this study was to assess, through a meta-analysis, the risk of developing work-related asthma associated with wood dust exposure. A systematic search of the literature was performed. Inclusion and exclusion criteria were applied and a quality scale used to measure the quality of the included studies was developed. Using standard meta-analysis techniques, studies were pooled using both random and fixed effects models. Nineteen studies were included which consisted of three cohort studies, twelve case-control studies and four mortality studies. The pooled relative risk (RR) of asthma among workers exposed to wood dust was 1.53 (95% CI 1.25-1.87). When the analysis was restricted to studies carried out on Caucasian populations, the pooled RR was 1.59 (95% CI 1.26-2.00) while the pooled RR of studies on Asian populations was 1.15 (95% CI 0.92-1.44). Wood workers present a higher risk of asthma. Future research should include careful evaluation of ethnicity and nativity as risk modifiers.