While most cases of lung cancer are caused by tobacco smoke, other hazardous substances can also lead to the formation of lung tumors. Exposure to these chemicals often occurs in the workplace. In fact, research shows that occupational exposures account for 15 percent of all lung cancer cases in men and 5 percent of cases in women.
Carcinogens are substances that are known to cause cancer in people. Carcinogens can alter the DNA in cells, causing mutations that can trigger rapid cell growth and division, which may eventually lead to the formation of a tumor. The International Agency for Research on Cancer and the U.S. National Toxicology Program are both responsible for defining substances as carcinogens. Carcinogens may include harmful chemicals, along with some hormones and medications used to treat different types of cancer.
Following are potential carcinogens that may raise the risk of lung cancer.
Asbestos is a naturally occurring mineral made of small, flexible fibers. It was often used in construction through the 1970s because it is resistant to corrosion, heat, and electricity. When asbestos is added to building materials such as plastic, paper, or cement, it makes these materials stronger.
While asbestos fibers are useful for their durability, they can also cause lasting damage if inhaled or ingested. The body cannot clear asbestos easily, and the asbestos becomes trapped. Trapped asbestos can lead to inflammation because the body’s immune system recognizes the fibers as foreign.
Over time, this inflammation can irritate the lungs and lead to lung cancer, particularly a rare type known as mesothelioma. This type of cancer is caused almost exclusively by exposure to and inhalation of asbestos fibers. Mesothelioma develops in the thin layer of tissue that covers the chest cavity and lungs known as the pleura.
Chronic inflammation from asbestos can also lead to a condition known as asbestosis, or scarring of the lungs. The scar tissue that forms can make breathing difficult, and breathing difficulties can become worse with smoking. Other symptoms include coughing, chest pain, and shortness of breath.
The most common professions that may lead to asbestos exposure include:
The Agency for Toxic Substances and Disease Registry estimates that around 27 million American workers were exposed to asbestos from 1940 to 1979. Once asbestos was discovered to be a carcinogen, it stopped being widely used. However, many older buildings still have asbestos within their walls or structures.
Exposure to certain metal compounds in manufacturing facilities and other workplaces can also lead to an increased risk of developing lung cancer.
Nickel is a metallic element that can be mined from the earth. When nickel is combined with other elements, it can form nickel compounds that are hard, strong, and resistant to heat. Some occupations where you may be exposed to nickel compounds include:
In these workplaces, the nickel compounds become dust particles or fumes that may then be inhaled into the lungs. The U.S. Occupational Safety and Health Administration has exposure limits for nickel compounds, which can help prevent lung damage and cancer.
Beryllium is a metal known for its light weight and ability to conduct heat and electricity. Beryllium can be found in products ranging from golf clubs to nuclear reactors. While beryllium is harmless in most of these products, processing the metal can lead to dangerous exposures.
Beryllium particles from different metals and alloys can enter the air during processing, and the particles can be inhaled into the lungs. Burning fossil fuels (particularly coal) also releases beryllium into the air, where it can be inhaled and increase the risk of lung cancer.
Cadmium is an abundant element found in small amounts in water, soil, air, and food. Cadmium is usually extracted from these sources along with other metals such as copper, zinc, and lead. Because cadmium does not corrode easily, it is used in metal coatings, plastics, and batteries.
When cadmium is being processed or made into specific products, the metal can form dust and fumes that can be inhaled into the lungs. Cadmium is also found in tobacco smoke — you can be exposed to this carcinogen from both cigarette smoking and secondhand smoke.
Chromium is a metal element that can be isolated from the earth’s crust. Chromium’s most useful form is as a hexavalent compound. Hexavalent chromium compounds are used in a variety of industries, including water treatment, chemical synthesis, textile dyeing, and more.
People who work with hexavalent chromium compounds are at an increased risk of developing lung cancer, along with cancer in the nasal cavity and sinuses. This is because the compounds can form mists, dusts, or fumes that are inhaled into the nose and lungs.
The most common workplaces where exposures are high include welding, chromate painting, and electroplating.
Benzene is a light yellow or clear liquid chemical that is used in pharmaceutical and chemical industries. Benzene is used as an ingredient for making other chemicals, and it can also be found in crude oil and gasoline. Products that contain benzene include adhesives, glues, paint strippers, and cleaning products.
While people can be exposed to benzene in workplaces that use or produce the chemical, benzene is also found in cigarette smoke. For people who smoke, 90 percent of benzene exposure comes from smoking cigarettes. While benzene has not been specifically linked to causing lung cancer, the exposure to benzene from smoking increases the risk of leukemia and other blood disorders.
Coke ovens are used to heat coal to produce coke, a product that is then used in steel and iron manufacturing. The production process creates emissions made of gases, dust, and vapors that contain substances known to cause lung cancer, including arsenic and cadmium.
Workers in the graphite, aluminum, steel, electrical, and construction industries are all likely to be exposed to coke oven fumes. The fumes are either inhaled into the lungs or absorbed through the skin. Exposure to these substances can increase the risk of lung cancer and kidney cancer.
Silica is a naturally occurring mineral commonly found in soil, sand, and stone. It is also found in construction materials, particularly quartz. When quartz or other stones are cut or ground, the stones can release crystalline silica dust into the air, which can be inhaled and embedded deep into the lungs.
Exposure to crystalline silica has been found to increase the risk of lung cancer. Particularly, workers who work in quarries or make pottery, ceramics, and bricks may all be exposed to the dust.
Coal tar is a substance made as a byproduct of producing coke. Coal tar can also be distilled, leaving another byproduct known as coal-tar pitch. Coal-tar pitch is a thick, black liquid used in paving and roofing and as a binder in asphalt used for roadways.
Coal tar and coal-tar pitch contain carcinogens, like benzene, that are known to increase the risk of lung cancer. Exposure can occur via absorption through the skin, ingestion, and inhalation into the lungs. Workers in foundries and aluminum production are likely to be exposed.
Arsenic is a naturally occurring compound that can also be made through industrial processes such as metal smelting and mining. Arsenic was used as a pesticide through the mid-1900s and in medications until the 1970s. One form of arsenic, arsenic trioxide, is used to treat a certain type of leukemia.
Arsenic is also found in tobacco smoke. Inhaling arsenic from smoking or industrial processes can increase the risk of developing lung cancer.
Diesel exhaust from vehicles contributes to air pollution, a known cause of lung cancer. Diesel exhaust is made up of two parts — soot and gases. Soot contains particles of organic materials, metallic compounds, and carbon. The gases contain carbon dioxide, carbon monoxide, chemicals known as polycyclic aromatic hydrocarbons, and more. The U.S. Environmental Protection Agency has classified diesel exhaust as “likely to be carcinogenic to humans.”
Certain jobs can increase the risk of exposure to diesel exhaust. Toll booth workers, truck drivers, heavy machine operators, miners, mechanics, and farm workers are all exposed to vehicles or machines that burn diesel fuel. Research has found that these occupations are at the highest risk of developing lung cancer from exposure to diesel exhaust.
Vinyl chloride is a colorless, synthetic gas that is made to produce polyvinyl chloride (PVC). PVC is used in plastics manufacturing for cable and wire coatings, pipes, and packaging materials. Cigarette smoke also contains vinyl chloride gas.
The main route of vinyl chloride gas exposure is through inhalation, either from breathing air in facilities that produce or use the gas or from breathing tobacco smoke. Research shows that exposure to the gas increases the risk of lung, liver, and brain cancers, as well as lymphoma and leukemia.
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