CANCER: CAUSES AND PREVENTION

        Cancer is a leading cause of death in California second only to heart disease. It accounts for 23% of all deaths. It can strike in a variety of forms at any age, increasing in frequency with age. According to present rates of cancer detection, about 30% of Americans will eventually get cancer. The five-year survival rate for all cancers is about 56% although the mortality rate for each type of cancer varies widely. If cancers are detected and treated early on, they can often be cured. Many can also be prevented through lifestyle changes, in particular, abstinence from tobacco and liquor.

        What is Cancer? Cancer is characterized by the uncontrolled growth and spread of abnormal cells within the body. Uncontrolled replication of cells causes a mass of tissue to form, commonly known as a tumor. Benign tumors are not cancerous and can usually be removed safely with no recurrence. Malignant tumors, on the other hand, contain invasive cells which damage the surrounding tissues and organs, and has the ability to spread to other parts of the body.

        There are more than 100 different forms of cancer, where the type of cancer is named after the initial organ affected. In the event of the cancer spreading, the abnormal cells in the new tumor are the same as those in the primary tumor. The most common forms of cancer in women are skin, breast, colon-rectum, lung and uterus, while for men, common cancers are skin, prostate, lung and colon-rectum.

        What Causes Cancer? Cancer is not contagious nor can an injury cause cancer. The exact mechanism for cancer has not been determined though many hypotheses exist. Certain factors have, however, been shown to be carcinogenic including the use of tobacco products, exposure to asbestos, radiation, certain chemicals including benzene and fluorocarbons, and excessive sunlight.

        What Carcinogens and Cancer Risks are Associated with Drinking Water? Chlorination of drinking water supplies has been a highly successful public health measure as it has been responsible for the control and reduction of many waterborne infectious diseases. However, the interaction of chlorine with organic matter in surface water produces chlorinated organic compounds. The types and levels of disinfection byproducts depend on the method of disinfection and the quality of source water. Trihalomethanes and haloacetic acids make up about 30% of all the halogenated organics, average levels being 40 mg/L and 20 mg/L, respectively. Some studies suggest that these chemicals may be associated with elevated risks of cancers of the bladder, colon, and rectum. Quantitative estimates of risk from drinking chlorinated surface waters, however, are uncertain especially since over 50% of the halogenated organic compounds have not been identified. Steps to reduce the exposure to disinfection-by-products include the proposed USEPA regulation to limit trihalomethane levels to 80 mg/L and haloacetic acids to 60 mg/L.




Source: http://www.ci.sf.ca.us/puc/wqfs/outbreak.htm