The use of pesticides in agriculture has increased over the last decade. Their widespread, often uncontrolled use causes thousands of people to be daily exposed to environmental agricultural chemicals, resulting in acute and chronic health effects. At present there is a paucity of data on the potential adverse effects of exposure to low levels of mancozeb for prolonged periods. In order to investigate the effects of mancozeb exposure on pulmonary wildlife populations, tracheas and lungs of nine 1- to 7- yr-old nonmigratory pigeons raised near peach orchards and vineyards repeatedly sprayed with the fungicide were examined. The experimental situation allowed us to evaluate the long-term natural toxicity of mancozeb as a sentinel for human populations occupationally exposed to fungicides. The use of nonmigratory pigeons may serve as an important biological source from which helpful data may be obtained for assessing risks to human health and gaining new insight into pathogenetic mechanisms.