Cancer and the Environment
What do we mean by environment?
The environment is your surroundings, like where you live, work, and play. It also includes the kinds of things people do.
Environmental factors include:
Lifestyle factors (tobacco use, weight, diet, alcohol, sexual behaviors). Changing these kinds of things can prevent about 90-95% of cancers.
Genetics contribute to about 5-10% of cancers. Often genetic cancers are caused by a mutation (mistake in the genes) that increases cancer risk.
Exposure to cancer causing substances, also called carcinogens, in the air, water, soil, and food.
Please take this pre-quiz to see what you know!
Cancer and the environment video 3.mp4Listen to our interview with Alex Whiting who is the Environmental Program manager for the Native Village of Kotzebue. Alex has decades of experience working with environmental issues in the Northwest Arctic Borough.
His message just might surprise you!
Environmental factors and genes contribute to the development of cancer. The types of cancers people develop are influenced by different causes.
Figure 1. The role of genes and environment in the development of cancer.
A. Percent contribution of genetic and environmental factors to cancer. About 90 to 95 percent of all cancers are caused by environmental exposures including the lifestyle choices people make. Only 5 to 10 percent of all cancer cases occur in someone who inherited a small change (called a mutation) in a gene that increases cancer risk.
B. Percent contribution of each environmental factor. For example, tobacco use and exposure to secondhand smoke causes 25 to 30 percent of all cancer cases.
Source: Anand, P., Kunnumakara, A.B., Sundaram, C. et al. Cancer is a Preventable Disease that Requires Major Lifestyle Changes. Pharm Res 25, 2097–2116 (2008). https://doi.org/10.1007/s11095-008-9661-9
What are carcinogens?
Any substance that causes cancer.
The National Toxicology Program (NTP), and the International Agency for Research on Cancer (IARC) have developed lists of substances that, based on the available scientific evidence, are known or are reasonably anticipated to be human carcinogens.
For more information on carcinogens please see: https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/carcinogens
How do we come in contact with carcinogens?
Soil
Air
Water
Food
Sometimes substances that can cause cancer naturally occur in the environment. Usually the risk is very small because the method or the amount of exposure is very small.
What are some examples of substances in the environment that can cause cancer?
Benzene is a colorless, flammable liquid found in gasoline and other solvents (a substance that can dissolve or extract other substances). Inhaling is the primary method of exposure. Leukemia is the type of cancer associated with this carcinogen. To learn more about benzene please see: https://www.cancer.org/cancer/cancer-causes/benzene.html
Asbestos are bundles of fibers that can be separated into thin, durable threads. They were used a lot in construction because asbestos is resistant to heat, fire, and chemicals, and doesn't conduct electricity. Asbestos, once released, such as when tearing down walls, can become lodged in the lungs and lead to lung cancer. To find out more about asbestos exposure please see: https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/asbestos/asbestos-fact-sheet)
What determines if cancer may occur from an environmental exposure?
To learn if a chemical will harm us, we need to ask these questions:
What was released?
Where? (point of exposure)
When?
And, it depends on how that chemical gets into our bodies:
How? (breathe, eat, touch)
How much? (concentration)
How often? (days per year)
How long? (number of years)
Why is it difficult for scientists to decide if an environmental exposure caused cancer?
Not all chemicals cause cancer.
It is not possible to tell exactly why a person has cancer.
Cancer-causing substances have different potencies (strengths).
Exposures may be worse for developing children.
Cancer may target different organs.
Some cancers have a genetic component so developing cancer can be a mix of genetics and environment.
There can be long periods of time between exposure and the appearance of a cancer. Sometimes it can take decades.
Should I be worried about my subsistence foods?
In general, subsistence foods are very healthy and high in nutrients and antioxidants. Being involved in getting subsistence foods can also help you get physical activity, stay connected to the land, and connected to your culture, which are all ways to stay healthy. Being active while doing subsistence activities counts as exercise which has been shown to prevent cancer. Subsistence activities can lower body fat and LDL-cholesterol (Coker et al. 2018).
