At the beginning of the 20th century, farmers were believed to be healthier than the general population. Exposure to fresh countryside air and physical work were thought to be the source of this improved health. During the 20th century this agrarian myth was shown to be incorrect—farmers not only had significantly higher rates of mortality from occupational injuries, but they also had higher rates of many chronic diseases such as cardiovascular and chronic obstructive pulmonary disease.¹ Higher rates of chronic diseases were observed despite the generally lower rates of cigarette smoking among farmers, suggesting that workplace exposures were contributing factors.² In the 1980s and 1990s there was markedly increased attention to the occupational health of farmers, and to respiratory effects of agricultural exposures. These studies confirmed that farming causes a wide range of respiratory diseases, including airway diseases such as asthma and COPD, hypersensitivity pneumonitis, interstitial fibrosis, infectious pneumonias, and toxic injuries such as silo filler’s disease and tracheo-bronchitis from numerous irritant chemicals.³ Indeed, the spectrum of respiratory diseases from agricultural exposures reads like a textbook of occupational lung disease, and is very different from many classic occupational lung diseases such as asbestosis that are associated with a narrow pulmonary response.⁴

The range of lung diseases resulting from agricultural work is not surprising when one looks at the breadth and high concentration of toxic exposures on the farm. Pulmonary toxins include organic dusts …