Sputum cytopathological findings in pig farmers.

The purpose of this study is to compare the cytological changes in the respiratory tracts of pig farmers exposed to an environment of swine confinement buildings with control, non-exposed subjects living in the same geographical area. Spontaneously produced sputum specimens were obtained from 133 pig farmers and 120 control subjects, all clinically healthy, and grouped according to smoking habits and sex. The findings of siderophages, eosinophils, abnormal columnar cells and respiratory spirals were significantly more frequent in the pig farmers. Siderophages were noted in 25.6% of pig farmers and in 5% of control subjects. By logistic regression analysis, pig farming is the single predictive factor for siderophages and eosinophils. For other cytological abnormalities, except Creola bodies and granular debris, smoking is the most significant predictive variable, but pig farming, age and male sex also correlate with smoking. Atypical squamous metaplasia was observed in 11.3% of pig farmers and in 5.8% of control subjects. These findings are in concordance with previous epidemiological and clinical studies and also reveal a new aspect of the harmful effect of pig farming exposure to the vascular and epithelial structures of the respiratory tract. It also demonstrates the usefulness of the simple method of sputum cytological analysis.