Predictors of occupational sensitisation to grain dust allergens and changes in lung function among grain mill workers in Cape Town

Occupationally-related airway diseases, including asthma and chronic obstructive lung disease, have emerged as having substantial public health importance. The aim of this study was to identify the predictors of occupational sensitisation to grain dust allergens and changes in lung function among grain mill workers in Cape Town. There were two major objectives of the study. Firstly, to determine which of the following factors determine the distribution of serum ECP (eosinophilic cationic protein): age, gender, grain dust exposure, smoking status, atopy and sensitisation to workplace allergens. Secondly, to investigate the risk factors associated with the following outcomes: i) sensitisation to occupational allergens; ii) diagnosis of occupational asthma; iii) diagnosis of chronic obstructive airways disease; and iv) longitudinal changes in lung function. The risk factors studied included age, gender, smoking habits, occupational exposure, lung function status on baseline survey (1989), and allergic sensitisation assessed at follow up (1996). The methods employed involved a repeat measures cross-sectional design including a cohort followed up at different points over a seven year period. Survey instruments included a questionnaire, spirometry and allergy tests (phadiotop, RAST for wheat, rye, Lepidoglyphus destructor, Tyrophagus putrescentiae and Sitophilus granarius). The results indicated an association of grain dust with pulmonary function and allergic sensitisation to grain dust constituents. After adjusting for known confounders such as age, gender and smoking, significant associations were found between employment duration and both decrements in lung function and sensitisation to wheat grain. A decrement of 278 ml in FEY 1 and 328 ml in FYC was associated with occupational sensitisation to wheat (and rye). Increasing employment duration resulted in annual decrements of 18.3 ml in FEY1 and 23 ml in FYC for every year employed. The odds for developing occupational asthma was only mildly elevated (OR=l.35) ...