| Summary: | Background: Previous studies have found woodworkers to be at an increased risk for nonmalignant
respiratory disease (NMRD) compared to control populations, and mould exposure
has been suggested as a possible cause of NMRD in woodworkers. The main objectives of this
thesis were to develop a predictive model of mould exposure among BC lumber mill workers
and to assess the risk of NMRD associated with mould exposure within a cohort of BC lumber
mill workers. Methods: In the first study, multivariate linear regression modeling was applied to
223 personal samples of B-(l,3)-glucan (a marker of mould exposure) collected at four BC
lumber mills, to produce a predictive model of mould exposure among workers. In the second
study, quantitative exposure values derived from the predictive model were assigned
retrospectively to a cohort of 11,200 BC lumber mill workers (employed at one of fourteen BC
mills between 1979 and 1994 for at least one year) to develop cumulative exposure estimates.
Morbidity was assessed using hospital discharge records (April 1, 1985 and July 31, 1997)
obtained from the BC linked Health Database. Exposure gradients among hospitalrzation rates
for any NMRD (ICD9=460-519), chronic obstructive pulmonary disease (COPD, ICD9=490-
92, 496) and asthma (ICD9=493) were assessed using Poisson regression, with workers in low
exposure categories acting as the reference population. Results: A total of 1097 cases of any
NMRD, 256 cases of COPD and 97 cases of asthma were included in analyses. After controlling
for age, calendar period and race (and employment in Western Red Cedar mills for asthma
analyses), there was evidence of an increase in COPD risk among high and moderate exposed
workers at no exposure lagging and lagging up to 5 years. There was some evidence of a link
between exposure and asthma, though no clear trends were apparent, and no evidence of a link
with any respiratory disease. Conclusion: This study provided evidence of a link between
cumulative mould exposure and hospitalrzation due to COPD among woodworkers. Further
studies with greater power and better control of possible conflunders are needed to fully assess
dose-response relationships between mould exposure and NMRD morbidity among BC
woodworkers. === Medicine, Faculty of === Population and Public Health (SPPH), School of === Graduate
|
|---|
