Meats cured with nitrites and nitrates may increase the risk of cancer, and children and pregnant women should probably limit their consumption of these foods. Epidemiological studies demonstrate that populations consuming high-fiber diets tend to have a low incidence of intestinal cancer. It is thought that fiber mitigates cancer risk by speeding waste through the colon and promoting the excretion of fats and bile acids. Iron deficiency has long been associated with an increased risk of esophageal cancer, but a normal diet provides enough of this mineral for most people, and many men already may have too much body iron. The high-fat diet consumed by most Americans probably contributes to the development of colon cancer, and possibly to cancers of the breast, prostate, and uterus.
Dietary fat stimulates the increased production of bile acids, some of which promote colon cancer.
When consumed in a high-fat diet, these chemicals are stored in human body fat, possibly increasing cancer risk. Industrial air and water pollution present a persistent health risk, particularly for workers consistently exposed to high levels of carcinogens. The link between occupational exposure to vinyl chloride, industrial dyes, and cancer is well documented. While medical diagnosis and even the curative treatment of cancer rely on the use of radiation, the high doses of ionizing radiation used to treat cancers are associated with a low but measurable risk of second tumors. Diagnostic x-rays use about a thousandth of a therapeutic dose.