US EPA

Carcinogenesis is a complex and dynamic interaction of host and environment. Important host factors include genetic constitution and health status. Among environmental factors, diet, pollutants in air and water, occupation, and life-style characteristics, such as smoking, are known to affect cancer development in the human population. This perspective represents a synthesis of our accumulated knowledge from epidemiology and animal experiments. Cancer epidemiology, in contrast to animal toxicological studies, requires no transference of the conclusions from the analysis of the animal data to indicate human carcinogenic potential. The long latency between the inception of cancer and its manifestation, and comparatively low incidence in human beings, as well as the difficulty of ascertaining exposure, have made an epidemiological approach demonstrating a cause and effect relationship between the suspected carcinogen and a specific cancer a very difficult if not impossible task. Long-term animal studies can provide tentative answers to questions posed by nonpositive but suggestive epidemiological studies. In addition, animal experiments have provided new perspectives on the interaction between the genome and the environment. The recent flurry of activity in basic research in oncogenes also reinforces Knudson and others observations regarding genetic influences on cancer development.

Chiu, A. AND D. Bayliss. ARE THERE CARCINOGENS IN WATER FOR HUMAN CONSUMPTION? AN EPIDEMIOLOGIST'S VIEWPOINT. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/A-94/112 (NTIS PB94190600).

Book Chapter: ater Contamination and Health: ntegration of Exposure Assessment, Toxicology, and Risk Assessment, Marcel Dekker, Inc., March 1994