Rural Lung Disease

One disappointing discovery is that living and working in rural areas is not healthier than living and working in cities. I have a lingering fantasy from childhood that country air was fresh and clean. The idea of the family farm as a pristine environment associated with health and happiness cannot be substantiated and may never have been true.

Rural agricultural workers are exposed to many air pollutants, including pesticides, herbicides and organic natural materials, which can cause disease. Inhalation injury can cause inflammatory reactions (bronchitis, asthma, and/or bronchiolitis) in the airway or lung tissue reactions - alveolitis, pulmonary edema and pulmonary fibrosis. At risk: 6.5 million farm workers and those who process, handle, transport, and service food products enroute to the marketplace. Also at risk are residents of rural areas who are exposed to dusts distributed by winds, sometimes hundreds of kilometers distant from the source of airborne contamination.

Diseases caused by organic dusts:

• hypersensitivity pneumonitis (HP)
• organic dust toxic syndrome (ODTS)
• occupational asthma, and bronchitis.

There are less defined syndromes, such as mucous membrane irritation syndrome, occupational chronic bronchitis, and symptomatic non-specific, non-asthmatic chronic airflow obstruction.  ODTS, also known as inhalation fever, results from exposure to high concentrations of organic dust, whether or not the dust is overtly moldy. It is a flu-like syndrome with or without respiratory symptoms and usually without X Ray evidence of pneumonitis or hypersensitivity. The symptoms may develop during or  hours after exposure.

Exposure working in and around grain elevators or silos, saw mills, and dry food processing plants are typical risk environments. Grain dust-induced lung disease results from the dust's biological activity, including its ability to cause respiratory tract irritation, inflammation, and functional change characterized by cough,  wheezing, chest tightness and shortness of breath. Chronic symptoms of bronchitis, and were found in 35% of non-smoking and 57% of smoking grain handlers. Hypersensitivity pneumonitis (HP) is a flu-like syndrome with shortness of breath. HP can be detected on X-Rays, lung function tests, and by lung biopsy.  If HP  is not recognized, several symptomatic episodes may result in chronic and irreversible lung disease with disabling sequelae.

Farmers

Farmers are also exposed to many chemicals that affect exposed skin and may cause respiratory problems through inhalation. Ammonia (NH₃) is used as a fertilizer and reacts with water to form a strong alkali that may damage the corneas and airways. It can reach toxic levels in animal buildings and may produce chronic bronchitis, bronchial reactivity, pulmonary fibrosis or bronchiolitis obliterans. Oxides of nitrogen (NO, NO₂, N20₄) are found in freshly filled silos and may cause death from asphyxia, laryngospasm, or delayed pulmonary edema. More commonly, they cause irritative symptoms (silo fillers disease), and farmers and silo workers who do not take adequate precautions are at risk when they enter the silo within 10 days after it has been filled.

Pesticides pose serious risks to agricultural workers because of toxic effects on the nervous and other organ systems at high exposure levels. They enter the body by inhalation through the nose and mouth into the lungs, absorption through the skin, or through the digestive tract. Some pesticides (e.g., organophosphates) may produce respiratory center failure and/or respiratory muscle weakness by their irritant effects on the airway. Others (e.g., chlorinated hydrocarbons, methyl-bromide, and carbondi-sulphide) may cause hemorrhagic pulmonary edema, and paraquat may cause pulmonary fibrosis.

Occupational deaths from pesticide exposure are uncommon but, in North America, over half of the grain elevator workers have claimed symptoms or health problems related to recognizable pesticide exposures at work. The risk of pesticide exposure is reduced by proper clothing, proper ventilation and the use of personal respirators.