Short term exposure to airborne microbial agents during farm work: exposure-response relations with eye and respiratory symptoms

Objectives - Exposure to high levels of non-infectious microbial agents is recognised as a cause of respiratory disease in working populations, but ex cept for endotoxins, little is known about exposure-response relations. As these effects do not depend on viability, exposure to nonviable microbial a gents is important. Various methods not based on microbial cultures were ex plored to study the complex microbial exposure of farmers and associations with acute symptoms during work. Methods - Airborne exposure was measured when farmers carried out specific tasks, Fungal spores, bacteria, endotoxins, beta (1-->3)-glucans, fungal an tigens specific for Penicillium and Aspergillus species, and mites were mea sured by methods not based on microbial cultures. Also silica, inorganic an d organic dust, ammonia, hydrogen sulphide, and nitrogen dioxide were measu red. Respiratory, and nose and eye symptoms experienced during measurements were recorded by a short questionnaire. Both univariate and multivariate s tatistical analyses were applied to assess the relations between exposure a nd acute symptoms. Results - 106 Farmers and their spouses participated in this study. Prevale nces of work related symptoms were: wheezing 3%; chest tightness 7%; cough 14%; eye symptoms 18%; and nose symptoms 22%. Prevalence ratios for nose an d eye symptoms were 4-8 after exposure to 20-500x10(3) fungal spores/m(3) a nd higher, and a prevalence ratio for cough was 4 after exposure to 500-17 000x10(3) fungal spores/m(3). Nose symptoms were also associated with expos ure to silica with prevalence ratios of 4-6 after exposure to 0.015-0.075 m g /m(3) and higher. Conclusions - Farmers had a high occurrence of symptoms of the nose and eye s as well as cough during work. These symptoms were associated in a dose de pendent manner with exposure to fungal spores. Nose symptoms were also asso ciated with exposure to silica.