ratory symptoms and bronchial reactivity among pig and dairy farmers. Scand J Work Environ Health 1994;20:48-54. OBJECTI VES -This study assessed the prevalence of respiratory manifestations among French pig and dairy farmers and determined the relationship between bronchial reactivity and respiratory manifestations. METHODS -The pig farmers included 102 men working more than halftime inside swine confinement buildings. There were 51 male dairy farmers and 81 male referents. The demographic characteristics of the three groups were similar except for more smokers among the referents. Each subject completed a standardized questionnaire. Pulmonary function tests were performed before and after a methacholine challenge (cumulative doses 80, 240, and 560 ug), Airborne dust, ammonia, and carbon dioxide were measured inside 28 swine confinement buildings. RESULTS -The pig farmers were exposed to a total dust level of 2.4 I mg . nr-'. The respirable particle concentration was low. The pig and dairy farmers had a significantly higher prevalence of cough and morning phlegm than the referents. Before the methacholine challenge, the dairy farmers had nonsignificantly lower mean lung function values than the other groups. Among the subjects with no history of asthma, nonspecific bronchial hyperreactivity was significantly higher among the pig and dairy farmers than among the referents. There was a fall in the forced expiratory volume in I s (FEY, ,) that was greater than 10% in 6.7% of the referents, 17.9% of the swine workers, and 35.6% of the~airy farmers. This result was unchanged after adjustment for the initial FEV] o: CONCLUSIONS -The prevalence of respiratory symptoms was significantly higher among the pig' farmers without base-line lung function impairment. However, both the pig and the dairy farmers had increased bronchial reactivity.Key terms: agricultural workers, epidemiology, occupational airborne exposure.Epidemiol ogic studi es have demonst rated an increased ri sk of respiratory dysfunction am ong farmers (1---4) and, especially, am ong workers in swine co nfinement building s (5-24). Th ese studi es iden-

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We studied the relationships between peak expiratory flow (PEF) variability and bronchial responsiveness to methacholine in 117 workers attending the annual compulsory examination (mean age, 38.7 yr +/- 9.5; men, 86.3%). Subjects recorded their highest PEF out of three, every 3 waking hours (i.e., five times a day) for 7 days, each using a newly purchased Vitalograph peak flow meter, and underwent methacholine challenge tests with a maximal cumulative dose of 1,200 micrograms. Those with a FEV1 fall of 15% or more were considered as reactors. The variability of PEF was expressed as the amplitude percent mean, calculated from daily amplitude (highest-lowest reading/mean reading of the day x 100), averaged over 6 days, from the second to the seventh. This index had a continuous distribution, skewed towards the greatest amplitudes, and correlated negatively with FEV1 (r = -0.25, p = 0.01). Subjects with asthma (n = 8) had greater variations. In the 109 nonasthmatics, greater variability was observed in subjects with wheeze apart from colds, breathlessness, or hay fever; the average amplitude was greater in reactors than in nonreactors to methacholine (16.9% versus 9.3%, p less than 0.001). The subjects with excessive PEF variability were all methacholine reactors, but they were only a subgroup of the reactors. These results provide evidence that excessive PEF variability is an indicator of bronchial hyperresponsiveness to methacholine in a population sample.

We assessed the relationship between exposure to silica dust and chronic airflow limitation in an epidemiological survey conducted among pottery workers and controls who were of the same socioeconomic status (average age: 35 y; 78% males). Data were collected by questionnaire for respiratory symptoms, allergy, respiratory history, smoking habits, and occupation. Lung function was measured with a computer-equipped Gauthier spirometer. We excluded subjects with silicosis or doubtful chest x-ray, and two exposure levels were defined. No differences were observed between exposed subjects and controls with respect to respiratory conditions. Mean pulmonary function values for men and women were significantly lower, after adjustment for age, height, and smoking habits, in even indirectly exposed pottery workers, compared with controls. These results suggest that exposure to silica dust is a risk factor for chronic airflow limitation and is independent of radiographic changes.

A previous cross-sectional analysis of 1980 data from a population of working men in the Paris area has shown a significant relationship of blood eosinophilia to a reduced FEV1 among nonsmokers, remaining after excluding men with a history of asthma. In the present report, we reexamine this relationship, after taking into account asthma, bronchial hyperresponsiveness, and positive skin prick tests, using data collected in 1985 in a subsample of 363 men from the initial population. Blood eosinophilia, defined by 5% or more eosinophils or by 250 or more eosinophils per cubic millimeter appeared to be associated with a lower FEV1, primarily in nonsmokers. A difference of approximately 0.40 L was observed in never-smokers with eosinophilia (greater than or equal to 5% of eosinophils) compared with those without. This association persisted after exclusion of subjects with atopy, asthma, and bronchial hyperresponsiveness. Longitudinally, no significant association was observed between 1980 eosinophilia and the annual FEV1 decline between 1980 and 1985, even in nonsmokers. The results of our cross-sectional analyses suggest that asthma or asthma-like disorder does not explain the association between eosinophilia and FEV1. The role of eosinophil in respiratory disorders may go beyond its intervention in allergy. Further longitudinal studies are needed to better understand discrepancies between cross-sectional and longitudinal data and whether eosinophilia is a risk factor for chronic air-flow limitation.