The environment is filled with substances that can potentially lead to cancer in humans. Many people
are familiar with some cancer-causing substances, which are broadly known as carcinogens.
For example, many homes install radon detectors to notify homeowners when harmful, cancer-causing
radon gas seeps inside. But there are many more carcinogens present around us, and it’s important to know where they can be and how we can limit our exposure.
Remember, while some substances have been linked to cancer, exposure to them does not always
lead to developing the disease. In addition to carcinogen exposure, a number of complex factors can
lead to the development of cancer, including lifestyle and genetic makeup.
Examples of Carcinogens in Nature
Arsenic is a common cancer-causing substance found in the environment. It occurs naturally in air,
water, and soil.
People can be exposed to arsenic by drinking contaminated water or eating plants fed by contaminated
water. Several types of cancer are associated with ingesting arsenic over extended periods of time.
Certain substances found in plants have been associated with cancer when the plants or their products are
ingested. Certain fungi found on plants like corn, peanuts, and tree nuts can contain aflatoxins.
Plants used for herbal medicines sometimes contain aristolochic acids. Both of these substances
have been linked to the development of cancer.
One of the most well-known cancer-causing agents in the environment is ultraviolet (UV) radiation
from the sun. Exposure to the sun can cause skin cancer.
Examples of Carcinogens in Building Materials
Exposure to asbestos, which is found most often in the construction and shipbuilding industries, has
been linked to lung cancer and mesothelioma, cancer of the chest and abdomen. Wood dust resulting from
cutting wood using machines or tools has also been linked to cancer.
People are exposed to coal-tar products when producing or using pavement tar, roofing tar, refractory
bricks, or other coal-tar coatings. Coal-tar products are associated with an increased risk of cancer,
particularly when they are absorbed through the skin, ingested, or inhaled.
Examples of Carcinogens in Byproducts of Manufacturing
The manufacturing of many products results in the inhalation of fumes and other byproducts that may
be high in carcinogens. Such cancer-causing substances include:
- Benzene– present in crude oil and frequently used in the chemical industry as a solvent or building block. Emitted from fires, including natural fires and burning cigarettes
- Beryllium– from the manufacture of products such as golf clubs, nuclear reactors, and aerospace components
- Cadmium– from industries that use cadmium to produce other metals
- Chromium– from industries such as stainless steel production, metal finishing, or welding
- Formaldehyde– from pressed woods during manufacture or subsequent use; also present in healthcare facilities and laboratories as disinfectant and preservative
- Nickel– from metal-working industries (mining, welding, etc.)
- Soot(can contain organic carcinogens as well as arsenic, cadmium, chromium)– from heating, burning, or demolition of various organic materials
- Vinyl Chloride– from the manufacture of vinyl products
Examples of Carcinogens in Tobacco Smoke
There is a strong, well-documented association between smoking tobacco and the development of
various types of cancer. Secondhand tobacco smoke, which is produced by smokers and inhaled by
those around them also can cause cancer.
According to the National Cancer Institute, second-hand tobacco smoke contains more than 7,000
chemicals and at least 69 of them are carcinogens. Many of the harmful substances listed above are
present in tobacco smoke, including arsenic, coal-tar products, benzene, cadmium, nickel, and
There is no safe level of exposure to cigarette smoke through direct inhalation or secondhand; people
should definitely not smoke and should take care to avoid breathing the smoke of nearby tobacco
Avoiding Cancer-Causing Substances
The United States has regulations in place to limit exposure to carcinogens in the workplace and
elsewhere in the environment. The National Toxicology Program and the International Agency for
Research on Cancer publish lists of known or suspected cancer-causing substances. Individuals can
reference these lists to understand the risks associated with contact with certain carcinogens and limit