Comprehensive Cancer Control Plan for Michigan, 2009-2015 Goals (2009 - 2015): Environmental / Occupational Cancers
Goal: Improve education about environmental/occupational exposures and cancer risk in Michigan.
Data Environmental Factors and Cancer Risk Environmental factors — which, from a scientist’s standpoint, include smoking, diet, and infectious diseases, as well as chemicals and radiation in our homes and workplaces — probably cause three-quarters of all cancer cases in the United States. Among these environmental factors, tobacco use, unhealthy diet, and inadequate physical activity are more likely to affect personal cancer risk than trace levels of pollutants in food, drinking water, and the air.1
However, the degree of risk from those pollutants depends on the concentration, intensity, and exposure. Substantial increases in cancer risk have been shown in settings where workers have been exposed to high levels of ionizing radiation, certain chemicals, metals, and other substances. Even exposures at low doses, which pose only small risk to individuals, can still cause substantial ill health across the whole population. For example, secondhand tobacco smoke increases cancer risk in the population at large when those who do not smoke are exposed to smoking by others.1
The following information details risks from some environmental (usually occupational) exposures that are known or suspected causes of cancer.
Chemicals and Radiation:
Some chemicals, such as benzene and asbestos, show definite evidence of causing cancer in humans. Others are considered probable human carcinogens (cancer-causing agents) based on animal experiments. These include dichlorodiphenyl-trichloroethane (DDT), formaldehyde, and polychlorinated biphenyls (PCBs).1
The only types of radiation proven to cause cancer in humans are ionizing radiation and ultraviolet (UV) radiation.1
Evidence that high dose of ionizing radiation causes cancer comes from studies of atomic bomb survivors, patients receiving radiotherapy, and certain occupational groups, such as uranium miners. Ionizing radiation can affect virtually any part of the body, but especially affects bone marrow and the thyroid gland. Diagnostic medical and dental x-rays are set at the lowest dose levels possible to minimize risk without losing image quality and medical usefulness.1
Exposure to sunlight (UV radiation) causes almost all cases of basal and squamous cell skin cancer and is a major cause of skin melanoma. Disruption of the earth’s ozone layer by pollution may cause rising levels of UV radiation.1
In addition, radon exposures in the home can increase risk of lung cancer. Cigarette smoking greatly compounds the effect of radon exposure in lung cancer risk. Remedial actions may be needed if radon levels are found to be too high in homes.
Public concern about cancer risks in the environment has typically focused on unproven risks, or on situations in which known carcinogen exposures are at such low levels that risks are negligible.1
Pesticides: Pesticides are widely used in producing foods in agriculture. High doses of some of these chemicals have been shown to cause cancer in animals, but the very low concentrations found in some foods have not been associated with increased cancer risk. In fact, people who eat more fruits and vegetables, which may be contaminated with trace amounts of pesticides, generally have lower cancer risks than people who eat few fruits and vegetables. Workers exposed to high levels of pesticides, in industry workers or in farming, may be at higher risk of certain cancers.1
Environmental pollution by pesticides such as DDT, which is now banned but was used in agriculture in the past, degrades slowly and can lead to accumulation in the food chain and persistent residues in body fat. These residues have been suggested as a possible risk factor for breast cancer, although the evidence has not been conclusive.1
Continued research into pesticide use is essential for maximum food safety. But, pesticides play a valuable role in sustaining the food supply. When controlled properly, the minimal risks they pose are overshadowed by the health benefits of a diverse diet rich in foods from plant sources.1
Non-Ionizing Radiation:
Electromagnetic radiation at frequencies below ionizing radiation and UV levels has not been proven to cause cancer. Some studies suggest it may be associated with cancer, but most of the research in this area does not endorse this finding. Low-frequency radiation includes radiowaves, microwaves, and radar, as well as power frequency radiation arising from electric and magnetic fields associated with electric currents (e.g., from cellular phones and household appliances).1
Toxic Wastes: Toxic wastes in dump sites can threaten human health through pollution of the air, water and soil. Many toxic chemicals found in such sites can be cancer-causing at high doses, but most community exposures appear to involve very low or negligible dose levels. Clean-up of existing dump sites and close control of toxic materials are essential to ensuring healthy living conditions.1
Nuclear Power Plants: Ionizing radiation emissions from nuclear plants are closely controlled and involve negligible levels of exposure for communities near the plants. Reports about cancer case clusters in such communities have raised public concern, but studies show clusters do not occur more often near nuclear plants than they do elsewhere.1
Occupational Cancer Risk
The causes of most cancers are not well defined, although epidemiologic studies have identified various environmental and genetic factors associated with some types of cancer. Some of the first observations of the relationship between environmental exposures and cancer were among occupational groups, including scrotal cancer in chimney sweeps (polycyclic aromatic hydrocarbons) and bladder cancer in workers exposed to dyes (aromatic amines). A variety of occupations have been associated with an increased risk of cancer, yet the etiologic agents have not been identified.2
The link between occupation and cancer is not easy to establish, because cancers associated with occupational exposures are indistinguishable clinically and pathologically from cancer of non-occupational origin. The generally long latency period between onset of exposure and disease adds to the difficulty of recognizing the association between work and cancer. In addition, non-occupational risk factors, such as cigarette smoking, may have a synergistic effect with a workplace exposure in the causation of cancer.2
Certain occupations are known to be associated with high cancer risks. Some of these include painters; furniture makers; workers in the iron, steel, coal, and rubber industries; and workers involved in boot and shoe manufacture or repair. Workers exposed to metals (e.g., arsenic, beryllium, cadmium, chromium, lead, and nickel) also have an elevated cancer risk.2
Mesothelioma, a cancer of the lining of the lung and abdomen, and hemangiosarcoma of the liver are the only cancers that are almost uniquely associated with exposure to asbestos and vinyl chloride, respectively.2
Mesothelioma: The Michigan Cancer Registry identified 1,471 incident malignant mesothelioma cases among Michigan residents for the years 1985 through 2000, for an annual average of 92. Incident cases increased from 58 in 1985 to 124 in 2000.2
Malignant mesothelioma incident cases predominately occurred in people 55 years of age and older (87 percent), in males (75 percent), and in whites (94 percent). Mesothelioma cases in the cancer registry indicated a definite upward trend over the 15 years of available data, consistent with trends seen in asbestosis, another disease associated with asbestos exposure.2
Hemangiosarcoma: Between 1985 through 2000, there were 22 incident hemangiosarcomas of the liver, or less than two cases per year. The cases were evenly distributed over the 15 years. Sixty-eight percent of the cases were between the ages of 55 and 84. Cases in males (59 percent) were more common than cases in females (41 percent), and whites accounted for 91 percent of the cases.
During the five years between1997 and 2001, 51 individuals filed workers’ compensation claims for cancer. This included:
Environment/Occupational Cancers Health Disparities Data
Malignant mesothelioma incident cases predominately occurred in people 55 years of age and older (87 percent), males (75 percent), and whites (94 percent).2
More populated counties in Michigan have a greater incidence of mesothelioma cases than less populated ones.2
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