Environmental Factors and Their Influence on Cancer Rates
by Eleanor G. Rogan, PhD, Professor and Chair, Department of Environmental, Agricultural, & Occupational Health; Professor, Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center
About one-third to one-half of US residents will develop cancer in their lifetime. Many will have simple, easily treated types of cancer, but others will have a more difficult time. Most biomedical scientists think that the environment in which we live and work plays a key role in determining whether we develop cancer. Our environment is anything we interact with. This includes our exposure to what we eat, drink, and breathe; natural and medical radiation; sunlight; substances in air, water, and soil; and workplace exposures to chemicals. Some people’s bodies also are better able to minimize the hazard posed by environmental compounds, while others are more susceptible.
Lung cancer is the most deadly form of cancer in men, and almost all lung cancer is related to smoking tobacco. Smoking also accounts for some bladder, mouth, colon, and kidney cancer. Even secondhand cigarette smoke poses a cancer risk for people exposed to it. Chewing tobacco and snuff add to the risk for cancer of the mouth, lip, throat, voice box, and esophagus.
Although exposure to asbestos fibers is much lower today, there still is some asbestos-related lung cancer. In addition, the fibers cause another type of cancer, mesothelioma, in the chest and abdominal cavity. Exposure to heavy metals, such as cadmium and chromium, which are used in paints, can lead to a variety of types of cancer.
While many cancer-causing substances are man-made, natural causes also occur. Too much exposure to UV radiation from sunlight can lead to melanoma or other types of skin cancer. Radon gas, which seeps out of the soil, can induce lung cancer, which is why people should have their homes tested for radon gas and, if the level is high, install equipment to reduce it in their homes.
Some industrial solvents cause cancer, but current workplace regulations in the United States keep levels pretty safe. One such solvent is benzene, which causes leukemia. Its industrial use is no longer a problem, but benzene is found in cigarette smoke and gasoline, posing a problem for all who are routinely exposed to them.
We can avoid some cancer risks if we put our minds to it. Scientists have estimated that tobacco use accounts for about 30% of cancers that could be avoided, and diets poor in vegetables and high in fats account for a similar amount. Ionizing radiation and UV sunlight account for about 4% of avoidable cancers. Today, exposure to pollutants in air, water, and soil is thought to account for as much as 5% of cancers. These estimates make it clear that people can make a difference in their lives by controlling their exposure to cancer-causing substances to reduce their risk of developing cancer.