Silo-Filler's Disease: One Health System's Experience and an Update of the Literature.

Silo-filler's disease, a life-threatening condition from exposure to silage gas in recently filled silos, has been known for over 5 decades now. However, farm workers remain exposed to this preventable condition. We describe the index presentations and subsequent changes among 19 patients managed within our health system over a 61-year period and highlight the need for ongoing education on minimizing exposure to silo gas.

Lung (agricultural/rural).

Industrialization of farming, animal raising, and forestry has added chemical and mechanical hazards that need to be recognized and prevented. Lung disease among farmworkers can result from a wide variety of hazardous exposures, which include organic dusts, allergens, chemicals, toxic gases, and infectious agents. In addition to nonspecific symptoms of mucous membrane irritation, farmworkers can experience occupational asthma or bronchitis, organic dust toxic syndrome, hypersensitivity pneumonitis, silo filler's disease (toxic hemorrhagic pulmonary edema), and neuromuscular respiratory failure. At risk are farmworkers and those involved in the processing, stocking, transportation, handling, and inspection of unprocessed agricultural, animal, and forestry products; veterinarians; gardeners; game, river, and forest keepers; persons involved in building, supplying, or servicing farm operations; and residents of rural communities. Worker education on the risks of environmental exposures, adherence to safety regulations, and increased knowledge of the cause and prevention of environmental diseases will reduce their prevalence and their adverse human and animal health and socioeconomic effects.

[Storage mite allergy. Routine tests]. / Formiddallergi. Rutinetesting.

Storage mites are sources of allergy among farmers and silo workers. Among 114 patients with allergic rhinitis we found four with a positive prick test to storage mites. This is not sufficient reason to include storage mites in a standard allergy prick test series.

[A case of silo-fillers' disease].

A 52 year-old male farmer was admitted to our hospital because of cough, sputum and dyspnea on exertion. Chest X-ray showed pulmonary edema and arterial blood gas analysis showed hypoxemia. Silo-fillers' disease was diagnosed because he had allegedly inhaled yellowish gas in the silo. The day following steroid therapy, symptoms and pulmonary edema improved. Silo-fillers' disease is chemical pneumonitis due to exposure to the oxides of nitrogen which are produced in silos. Although reported cases of silo-fillers' disease in Japan are rare it should be kept in mind in areas involved with dairy farming.

Silo-filler's disease.

Between 1955 and 1987, 17 patients were examined at the Mayo Clinic shortly after exposure to silo gas. All exposures had occurred in conventional top-unloading silos. Acute lung injury occurred in 11 patients, 1 of whom died; early diffuse alveolar damage with hyaline membranes and hemorrhagic pulmonary edema and acute edema of the airways were found at autopsy. In one patient, hypoxemia and transient obstruction of the airways developed, but no pulmonary infiltrates were noted. One patient had symptoms for 5 weeks and diffuse confluent pulmonary infiltrates; many years later, chronic obstructive pulmonary disease developed (he had, however, been a heavy smoker before exposure). Bronchiolitis obliterans was not observed in the other patients, probably because of less severe exposure or early corticosteroid therapy. Prophylactic corticosteroid therapy is advised for workers who have been exposed to silo gas. The management of patients with established acute lung injury is reviewed. Previously unreported patterns of exposure to silo gas in conventional silos are described, and recommendations for avoiding exposure are suggested.

Grain dust and the lungs.

Grain dust is composed of a large number of materials, including various types of grain and their disintegration products, silica, fungi, insects and mites. The clinical syndromes described in relation to exposure to grain dust are chronic bronchitis, grain dust asthma, extrinsic allergic alveolitis, grain fever and silo-filler's lung. Rhinitis and conjunctivitis are also common in grain workers. While the concentration and the quality of dust influence the frequency and the type of clinical syndrome in grain workers, host factors are also important. Of the latter, smoking is the most important factor influencing the frequency of chronic bronchitis. The role of atopy and of bronchial hyperreactivity in grain dust asthma has yet to be assessed. Several well designed studies are currently being carried out in North America not only to delineate the frequency of the respiratory abnormalities, the pathogenetic mechanisms and the host factors, but also to establish a meaningful threshold limit concentration for grain dust.