Environmental factors and the development of disease and injury in the alimentary tract.

This review examines interactions between the alimentary tract and environmental agents. In these intera"ctions the alimentary tract is considered as an integrated organ system extending from mouth to anus. The alimentary tract shares with the skin and its appendages and the respiratory system the distinction of being a portal of entry into the human body for environmental agents as well as a target for their action. Food and water-borne environmental agents enter the body via the alimentary tract. By injurying the alimentary tract environmental agents after their portal of entry and thereby modulate their effects on the organism. Such modulation may enhance or depress effects of these agents. Interactions between environmental factors and the alimentary tract depend on (1) factors related to the alimentary tract that are determined by anatomic, physiologic, and biochemical considerations; (2) factors related to the environmental agents; and (3) individually determined factors. The role of these factors in development of disease and injury is considered. Environmental diseases of the alimentary tract and environmental agents acting on the gut are discussed and recommendations are made for future research.