What are occupational exposures that can lead to cancer?
Related conditions: Cancers linked to occupational exposure include leukemia, lymphoma, and cancers of the lung, breast, bladder, skin, larynx, nose, throat, prostate, pancreas, liver, scrotum, and soft tissue.
Workers at risk: The International Agency for Research on Cancer (IARC) has identified over one hundred known and about one hundred suspected occupational carcinogens. Certain workplaces and jobs carry a greater risk of exposing workers to substances that may increase their chance of cancer. The workplace may be indoors, as with restaurant or factory workers, or outdoors, as with landscapers or construction workers. Because the effects of exposure to occupational toxins usually do not surface until years after exposure, linking the cancer to the workplace is sometimes difficult. However, one in five workers is exposed to and at an increased risk for cancer from toxins in the workplace.
The World Health Organization (WHO) reported that of the more than seven million deaths from cancer each year, about 40 percent could be prevented by dedicated efforts to reduce workplace toxins. Occupational cancer claims more lives than any other work-related disease (32 percent; circulatory disease claims 26 percent) or even work accidents (17 percent). The incidence of occupational cancers is from 4 to 20 percent of all cancers but may be higher, as many go unreported. In the United States, each year about twenty thousand people die of cancers attributed to occupational toxins and about forty thousand people are newly diagnosed with cancers due to occupational causes. Globally, an estimated 609,000 workers are affected yearly.
Lung cancer: Lung cancer has been linked to occupational exposure to numerous substances. Lung cancer, particularly mesothelioma, is high in people exposed to asbestos and can develop years after the exposure. If the person exposed to asbestos is a smoker, that person is fifty to ninety times more likely to be diagnosed with lung cancer compared with the average person. Asbestos has been used to strengthen the walls of buildings; as insulation for walls, boiler pipes, and steam pipes; and as soundproofing. In 1989, the United States Environmental Protection Agency (EPA) banned most asbestos-containing products. Although the ruling was overturned in a 1991 appeal, some asbestos-containing products remain prohibited, and all nonhistorical, or new, uses are banned. Therefore, automobile parts manufacturers still use asbestos in brake shoes and clutch linings. Some products contain substances that may be contamined with asbestos, such as vermiculite (in garden products) and talc (in crayons). Asbestos often is present in the ceiling or floor tiles in older buildings. Workers who remove asbestos-containing materials from old buildings need to use protective masks to avoid inhalation and cover their clothes so they do not take asbestos dust home with them. Other industries where employees can be exposed to asbestos are railroads, insulation factories, and shipbuilders.
Lung cancer risk is increased for people who work in places where they are exposed to secondhand smoke, such as bars, casinos, bowling alleys, or restaurants; tin miners and refining industry workers who are exposed to toxins such as arsenic, nickel, or chloromethyl ether; and quarrying, stone industry, and glass-manufacturing workers exposed to silica dust.
Radon, a natural radioactive gas that causes lung cancer, is present at harmful levels in one in fifteen homes by the EPA’s estimate. Chemicals inhaled by painters, chemists, and printers increase their risk of lung cancer. Formaldehyde, a chemical used to disinfect surgical rooms and dialysis units and also found in carpet and furniture glues, diesel fumes, and embalming fluid, is believed to cause respiratory cancers.
Bladder cancer: Bladder cancer has been linked to exposure to dyes containing benzine and naphthylamine. IARC found a small increased risk of developing bladder cancer among barbers and male hairdressers. However, some cancer-causing coloring agents were removed from dyes in the 1970s, and the study was unable to determine if the risk was caused by past or present exposure to carcinogens. Employees who work with rubber, paint, or leathers may also be at greater risk of developing bladder cancer.
Skin cancer: Skin cancers such as melanomas are more common in workers who are exposed to the ultraviolet (UV) radiation from the sun. Workers at greater risk include construction workers, farmworkers, landscapers, roofers, and fishing boat workers. Asphalt and diphenyls as well as reflections from water, sand, concrete, snow, and any light-colored surface increase the harmful effects of UV rays.
Other cancers: Workers exposed to herbicides and pesticides have an increased risk of lymphomas. Farmers and others working with these chemicals demonstrate a higher incidence of prostate cancer. Pancreatic cancer is associated with pesticides, dyes, and gasoline. Health care workers can be exposed to occupational toxins as well as body fluids that harbor hepatitis B and C viruses, which can cause liver cancer.
Prevention and policy: Occupational exposures to carcinogens can be limited and in many cases are preventable. Removing the risk or the toxin from the workplace is the primary way to prevent occupational cancer. When the carcinogen cannot be removed from the environment, as in the case of UV rays, workers can use protective clothing and sunscreens, and work practices can be altered to minimize exposure (such as providing a shady place for breaks and lunches). The WHO’s Global Occupational Health Network offers the following steps to prevent occupational cancers:
- Develop regulations and an enforcement process for monitoring carcinogens in the workplace.
- Avoid use of known carcinogens in the workplace.
- Replace known toxins with safe substitutes.
- Educate workers about primary prevention of work-related cancers.
- Implement a health surveillance program for workers exposed to occupational toxins.
Several other approaches can decrease the risk of occupational cancer. These include testing of new chemicals before they are placed on the market, keeping hazardous toxins in an enclosed area with adequate ventilation, and using protective masks and clothing. Workers are advised to avoid smoking, as the incidence of occupational cancer increases with tobacco use. All workers must examine and weigh the risk that each occupation brings, as few jobs are risk-free, but some involve more exposure than others.
The prevention of occupational cancer is directly related to legislation as laws are needed to control the use of carcinogens and to provide workers with adequate protection from exposure. Legislators, politicians, lobbyists, unions, and grassroots occupational health groups have brought pressure on the various industries to introduce protective laws and stricter inspections.
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