Comparison of dust related respiratory effects in Dutch and Canadian grain handling industries: a pooled analysis.

Abstract

Objectives-Four previously conducted epidemiological studies in more than 1200 grain workers were used to compare exposure-response relations between exposure to grain dust and respiratory health. Methods-The studies included Dutch workers from an animal feed mill and a transfer grain elevator and Canadian workers from a terminal grain elevator and the docks. Relations between forced expiratory volume in one second (FEVy) and exposure were analysed with multiple regression analysis corrected for smoking, age, and height. Exposure variables examined included cumulative and current dust exposure and the numbers of years a subject was employed in the industry. Sampling efficiencies of the Dutch and Canadian measurement techniques were compared in a pilot study. Results of this study were used to correct slopes of exposure-response relations for differences in dust fractions sampled by Dutch and Canadian personal dust samplers. Results-Negative exposure-response relations were shown for regressions of FEV, on cumulative and current exposure and years employed. Slopes of the exposure-response relations differed by a factor of three to five between industries, apart from results for cumulative exposure. Here the variation in slopes differed by a factor of 100, from -1 to -0-009 mllmg.ylm'. The variation in slopes between industries reduced to between twofold to fivefold when the Dutch transfer elevator workers were not considered. There was evidence that the small exposure-response slope found for this group is caused by misclassification of exposure and a strong healthy worker effect. Alternative, but less likely explanations for the variation in slopes were differences in exposure concentrations, composition of grain dust, exposure characteristics, and measurement techniques. Conclusion-In conclusion, this study showed moderately similar negative exposure-response relations for four different populations from different countries, despite differences in methods of exposure assessment and exposure estimation. (Occup Environ Med 1996;53:559-566)

Asthma and allergy in New Zealand farmers

“…The reasons for the lower overall prevalence of asthma in New Zealand farmers are likely, at least in part, to be accounted for by the healthy worker effect which is particularly strong for non-malignant respiratory disease [Pearce et al, 1988]. In particular, other studies have reported decreasing asthma prevalence with number of years worked in agricultural occupations [Peelen et al, 1996;Chan-Yeung et al, 1979]. This pattern was also found in the current study where a (nonsignificant) negative association with duration of employment and asthma was seen, independent of age.…”

Occupational Airways Disease from Chronic Low Level Exposure to Mineral Dusts, Organic Dusts, and Mixed Exposures: Occupational Chronic Obstructive Pulmonary Disease

“…More recently, evidence of airflow obstruction associated with lower levels of grain dust has emerged from a series of well-controlled epidemiological studies (most with measurements of exposure levels). 7,[66][67][68][69][70] These studies provide consistent evidence showing exposure-related airflow obstruction in nonsmokers and smokers. There is also evidence for a strong "healthy worker effect," favoring the least-affected individuals to remain in the exposed work force.…”

“…82 Most of the epidemiological studies with detailed pulmonary function measurements showed chronic airflow limitation. However, some studies 7,52,66,70,83,84 found that exposure to both grain and wood dust induced changes in FVC equal to the reductions in FEV1, suggesting the possibility of alveolar duct or parenchymal involvement as well. Furthermore, some of the wood dust studies have implicated exposure to visible mold as well as dust in dose-response analyses.…”

PM2.5 in Indoor Air of a Bakery: Chemical Characterization and Size Distribution

“…In workplaces where grain is handled, there is substantial evidence that workers develop respiratory symptoms related to high concentrations of dust micro-and macroparticulate fractions produced by various stages of the industrial process [22][23][24][25][26][27][28][29][30]. In particular, bioaerosols have been widely studied in different occupational and nonoccupational settings, such as bakeries and flourmills [31,32].…”