"Environmental medicine deals with diseases that other physicians encounter in their practice, whether cancer, lung disease, contact dermatitis or other chronic and acute diseases. The physician practicing environmental medicine focuses on the nexus between the patient or a group of people and the environment and utilizes disciplines from the environmental sciences that analyze the four major environmental media: air, water, soil and food. As a discipline, environmental medicine shares concerns, protocols and knowledge base with preventive, community, and occupational medicine. Historically, environmental medicine involved studying and controlling infectious disease, but the focus has moved to chemical and physical hazards in the environment. For other medical specialties, such as a primary care, environmental medicine principles and practices may help the clinician isolate the cause of the patient's problems and take the appropriate steps for a physician to help the patient and community prevent ill-health effects from environmental exposures."
Michael Gochfield, in Environmental Medicine, pp. 3- 8.
Exposure assessment examines potential and actual exposures to hazardous agents through the media of food, water, air and soil or a combination of any of these four media. Upon determining the exposure source, exposure media, and the hazardous agent, the investigator needs to characterize the exposure in terms of amount, duration of exposure and frequency of exposure. This exposure assessment is then as part of a risk assessment.
Stuart Brooks, Lynette Benson, and Michael Gochfield, in Environmental Medicine, eds. Stuart M. Brooks, Michael Gochfield, Jessica Herzstein, Richard J. Jackson, and Marc B. Schenker, Mosby, 1995, pp. 9 - 14.