20 Common Chemicals and Pollutants That Can Increase the Risk of Cancer - Particularly in Children
The following excerpt is from Children and Environmental Toxins: What Everyone Needs to Know, by Philip J Landrigan and Mary M. Landrigan (Oxford University Press, 2018). Reprinted with permission.
Most childhood cancer is diagnosed during the child’s first five years of life, with a peak incidence during the first year. The most common childhood cancer is leukemia, followed by lymphomas and brain cancers.
There are known links between toxic chemicals and childhood cancers, but much more research is necessary to determine why childhood cancer is on the rise. Since many childhood cancers appear early in the child’s life, research is focusing attention on prenatal exposures to cancer-causing agents as one piece in the puzzle of rising numbers of childhood cancer.
There are a number of known carcinogens (cancer-causing substances) that can increase the risk of cancer in children and adults. A partial list of carcinogens are discussed here in brief snapshots that incorporate information from the International agency for Research on Cancer, the National Cancer Institute, the Environmental Protection Agency, and the Centers for Disease Control and Prevention.
Aflatoxins are a group of toxic chemicals produced in warm, damp climates by various types of fungi and molds that grow on peanuts, corn, and other nuts. Aflatoxins can cause liver cancer in people who ingest contaminated food products. Cancer risk is greatest in people with liver damage or chronic infection with hepatitis B. Children can be exposed to aflatoxins in peanut butter made from peanuts contaminated with the fungus.
Air pollution is the aerosolized “toxic chemical soup” that we now all breathe. Outdoor air pollution includes breathable fine particulates of soot from vehicle exhaust and industrial smokestacks, as well toxic gases from fuel combustion—carbon dioxide, nitrogen oxides, carbon monoxides, and other chemical compounds. The reaction of these fine particulates and toxic gases with ground-level ozone, a respiratory irritant formed when ultraviolet light or electrical discharges react with oxygen, produces urban smog. Outdoor air pollution is a carcinogen.
Indoor air pollutants are also potentially toxic: carbon monoxide, radon, fumes from deodorizers, cleaners, household products, new building materials or furniture, household pest droppings, tobacco smoke, pollen, and mold.
A wide array of negative health effects—cancer, respiratory diseases, asthma, cardiovascular diseases, and premature birth have been linked to air pollution. Diesel exhaust is considered to be a proven lung carcinogen.
Anabolic steroids, particularly anabolic androgenic steroids used illegally by some athletes to enhance muscle bulk and improve performance, are carcinogenic. They have been shown to be a cause of liver cancer. Children and teens are at special risk because they may see steroids as a way to improve their athletic performance in competing for places on sports teams. In addition to the severe penalties for steroid use that are imposed by the governing bodies of organized sports, the health risks of steroid use are enormous. Steroids should never be used for any purpose having to do with athletics by persons of any age. The purported short-term gains are tiny compared with the damage steroids can cause.
Arsenic is a naturally occurring chemical element that can be found in air, water, and soil and that can cause cancers of the bladder, skin, lung, gastrointestinal system, liver, kidney, and blood. It occurs as a contaminant in water supplies, which can result in chronic exposure. It is also released into the environment by agricultural and smelting industries. Arsenic was used as a pesticide in the past and is still found in some manufactured products.
Children can be exposed to arsenic when they play near old wooden structures made of pressure-treated wood that was treated with chromated copper arsenate (CCA). Commonly used in earlier years for playground equipment and outdoor decks, CCA is an arsenic compound that can be ingested by children playing in the soil around the structures or from contaminated dust. Recent studies have shown that arsenic continues to leach from the treated wood for at least 7 to 10 years after installation.
Asbestos is the name given to a group of fibrous minerals that occur naturally in geologic formations around the world, but especially in Canada, Russia, Brazil, Western Australia, and South Africa. All types of asbestos are known carcinogens and must be carefully avoided. Asbestos fibers have been used extensively in the United States and elsewhere in shipbuilding and building construction since the early 20th century. Billions of tons of asbestos have been used in homes, public buildings, and schools in the United States and worldwide. Asbestos does not burn and is easily fabricated into insulation, fire-proofing, ceiling tiles, roof shingles, boiler coating, floor coatings, and spray-on wall and ceiling beam coverings.
As asbestos-containing tiles and insulation age and deteriorate, tiny, powdery fibers of asbestos are released into household air and house dust. When inhaled or ingested, these fibers can enter the body and remain dormant for decades. Up to 50 years later, they can cause lung cancer, gastrointestinal cancer, and malignant mesothelioma, a life-threatening cancerous tumor that is specific to asbestos.
Children are at risk of asbestos exposure from deteriorating ceiling coverings in older schools treated with asbestos and in multiple other buildings treated with asbestos products. Removal of asbestos should be done only by specially trained workers, ideally during school vacations, since the dispersion of asbestos fibers during renovations or the demolishing of a building puts people exposed to the fibers at risk of cancer.
Aspartame is an artificial sweetener that has been widely used since the 1980s and is found today in thousands of products worldwide, notably in diet beverages. Previously it was considered safe, but large, long-term animal studies are now indicating that aspartame may be a potential cause of leukemia. Exposures to aspartame during pregnancy appear to especially hazardous and are associated in animal studies with increased rates of cancer in offspring.
Benzene is a thin, colorless, sweet-smelling solvent used in industry and manufacturing. Commercial products containing benzene include paint strippers, cleaners, adhesives, and glues. Exposure to benzene can cause leukemia, lymphoma, and other blood disorders.
Benzene was once a widely used solvent valued as a household spot remover and solvent for grease related to automotive or handyman projects in the home. However, the major risk to children today from benzene is through exposure to gasoline, which contains benzene. Children and teens can be exposed to benzene while pumping gasoline at a self-service station or when fueling small engines, such as lawnmowers. Benzene can also be absorbed into the body through the skin if fuel is splashed onto the skin.
Benzopyrene is a black, sooty, burnt substance that is formed when grilling food, burning toast, or roasting coffee and smoking tobacco. Car exhaust, wood fires, and forest fires can also contain benzopyrene. Benzopyrene has been linked to stomach and lung cancer.
Cadmium is a metallic element linked with bladder and possibly pancreatic cancer. A component of outdoor air pollution, cadmium is released into the environment from incinerators and zinc refineries. Commercial uses of cadmium include paint pigments, plastics, and batteries. Cadmium is also found in tobacco smoke.
DDT is an organochlorine pesticide that has been recently linked to breast cancer when exposure occurs early in life. Women who were exposed to DDT as young girls have a higher incidence of breast cancer in later life than other women. An elevated risk of breast cancer is also seen in women whose mothers who were exposed to DDT while they were pregnant with them. These findings demonstrate how toxic environmental exposures during windows of developmental vulnerability in early life influence risk of disease across the life span.
Diethylstilbesterol (DES) was a medication given in the 1960s and 70s to pregnant women who were in danger of having a miscarriage or spontaneous abortion. It is a known cause of vaginal cancer in young women who were exposed to it prenatally and it also causes some reproductive changes in males. There are some data indicating that the health effects of DES may be multigenerational.
Diesel exhaust contains dirtier and more toxic fumes than gasoline exhaust. Diesel exhaust is comprised of soot, carbon dioxide, carbon monoxide, several oxides of nitrogen and sulfur, formaldehyde, and benzopyrene. One of the most toxic components of diesel exhaust is 1,3-butadiene, a powerful carcinogen. Diesel exhaust has been classified as a known human carcinogen.
Dioxins are highly toxic, cancer-causing chemicals that are produced during the incineration of PVC plastics and other chlorine-containing compounds, such as PCBs. They are persistent organic pollutants (POPs) and have been found in milk, food, and even infant formula and breast milk. High-fat foods, such as meat, milk, and eggs, contain trace amounts of dioxins that are transferred to people who eat these foods. The Centers for Disease Control and Prevention annual survey lists dioxins as one of the 200 environmental chemicals found in the bodies of most Americans. (See also TCDD.)
Formaldehyde is a chemical widely used in household products, such as particleboard, pressed wood, plywood,glues, adhesives, paper products, insulation, and industrial resins. Perhaps it is best known as the chemical responsible for the “new furniture” or “new car” smell that is detected as newly purchased items release formaldehyde into the environment. Formaldehyde has been linked to leukemia and other cancers.
Lindane, also known as HCB (hexachlorobenzene), is an insecticide banned for agricultural use by the Environmental Protection Agency (EPA) in 1976 because it is a persistent organic pollutant. However, lindane is still available by medical prescription as a treatment for lice. It is a cause of liver cancer. Safer treatments for head lice now exist.
Nitrosamine is a toxic chemical produced in the body during the digestion of nitrate-containing preserved meats, such as hot dogs, luncheon meats, and sausages. This carcinogen is also found in tobacco smoke. Nitrosamines are classified as probable carcinogens linked to digestive system cancers.
PCBs (polychlorinated biphenyls) are highly chlorinated compounds formerly used in electrical insulation. They are highly persistent in the environment. They have been classified as carcinogens.
Perchloroethylene, also called PERC or tetrachloroethylene, is a solvent used in dry cleaning and metal degreasing. It is a probable carcinogen that may be linked to leukemia, bladder cancer, and lymphomas.
Pesticide exposure is linked various types of cancer, especially among farmworkers, their families, and people who live in agricultural areas. Several pesticides—glyphosate (RoundUp), malathion, and diazinon—have been classified as probable human carcinogens with links to lymphomas and other cancers. Tetrachlorvinphos and parathion are classified as possible carcinogens on the basis of data from animal studies.
Radiation has many forms, and each kind of radiation contains a specific amount and type of energy. The forms of radiation differ from one another in the ways they deliver energy to the human body and in the damage they produce.
Radiation causes injury to the body by transferring energy to the cells through which it passes. Different forms of radiation behave in very different ways, are found in different environmental settings, and can cause quite different types of injury. However, energy transfer is always the fundamental mechanism of radiation injury.
The transfer of energy that is produced by radiation is similar to other common energy transfers, such as the transfer of energy in a car crash or being hit by a baseball. When the moving object hits the body, it slows down by transferring its energy to the body’s tissues and bones, causing cuts and abrasions or a broken bone. In a similar fashion, when a particle of radiation passes through the body, it collides with single atoms or molecules deep within the cells.
High doses of ionizing radiation, the type of radiation found in X-rays, radiation therapy, or atomic bombs, kill cells as it passes through the body. Deep burns, eye injury, and death from radiation sickness are some of the results. Destruction of bone marrow can occur. With the destruction of bone marrow, the body loses its ability to make new red and white blood cells; anemia and an impaired ability to fight off infection result. Destruction of the cell lining of the gastrointestinal tract is another feature of acute radiation sickness and this can cause death.
Lower-dose exposure to ionizing radiation causes subtle damage that may not appear for many years. At lower doses, radiation can alter and distort molecular structures within the cells of the human body. DNA, the fundamental human genetic material, is the most vulnerable target. When radiation strikes the nucleus of a cell, a change in DNA called a mutation occurs. Mutations caused by radiation can transform cells, leading to their becoming malignant and developing into widespread cancer.
In 1990 the National Academy of Sciences stated that there are no safe thresholds for exposure to ionizing radiation. Even the smallest doses are capable of causing mutations in DNA. In general, the higher the radiation dose, the more severe the effects on the human body, the greater the likelihood of mutation, and the greater likelihood of eventually developing cancer.