How long do carcinogens stay in the body?

There is no one specific answer to this question. Some carcinogens leave the body quickly but can cause damage that is long lasting. Other carcinogens may remain in the body for a longer period of time.

How many known carcinogens are there?

According to the IARC, who rates carcinogens, there are 121 known carcinogens to humans.

Carcinogens and How They Cause Cancer

By

Julie Scott, MSN, ANP-BC, AOCNP

Updated on May 17, 2022

Medically reviewed by

Gagandeep Brar, MD

Cancer is a disease of abnormal DNA and abnormal cell growth. When cancer starts to grow, the cell with abnormal DNA doesn't behave normally. The cells may grow and divide too rapidly, or may not die when they are supposed to.

Many risk factors are associated with the development of cancer, one of them being exposure to carcinogens. A carcinogen is a substance that has the potential to cause cancer. This article will review carcinogens and the mechanism in which they can cause cancer.

cigarette being lit — Zero Creatives/Cultura/Getty Images

How Carcinogens Cause Cancer

Carcinogens can be chemical substances, viruses, or even medications or radiation therapies used to treat cancer. Carcinogenic substances can cause cancer in different ways.

One of how carcinogens can lead to cancer is through direct damage to the DNA inside of a cell. The damage done by the carcinogen directly to the DNA then causes that DNA to become abnormal and not continue to function normally. This eventually leads to the development of cancer.

Another way that carcinogens can cause cancer development is more indirect. When damage occurs to a cell's DNA, there are repair processes that the body has to try to fix that damage. Sometimes the damage caused by the carcinogen interferes with the ability of the repair work, which has caused mutations in the function of those cells. The body is then unable to repair the damage, leading to cancer development.

People can be exposed to carcinogens in a wide variety of ways, including:

Lifestyle choices: Foods, smoking habits, lack of physical activity
Natural exposures: Ultraviolet light, radon gas, and infectious agents
Medical treatments: Radiation, chemotherapy, hormones, immunosuppressants
Workplace exposures: Exposure to industrial chemicals or products while at work
Household exposures: cleaning products, paints, herbicides, pesticides
Pollution: outdoor air pollution or even secondhand tobacco smoke

Some carcinogens do not directly cause cancer but can lead to cancer. Some carcinogens cause cancer if you have long-term, high levels of exposure.

Your risk of developing cancer depends on when, how often, and how long you are exposed to a carcinogen. Your genetic makeup also plays a role.

Classification of Carcinogens

Carcinogens are classified by The International Agency for Research on Cancer (IARC). The IARC puts substances into one of five groups based on the strength of the evidence that they can cause cancer in humans.

Category	Classification	Human Evidence	Animal Evidence
Group 1	Carcinogenic to humans	Sufficient	Sufficient
Group 2A	Probably carcinogenic to humans	Limited	Sufficient
Group 2B	Possibly carcinogenic to humans	Limited or inadequate	None or inadequate
Group 3	Carcinogenicity not classifiable	None or inadequate	Inadequate or limited
Group 4	Probably not carcinogenic	Suggests not carcinogenic	Suggests not carcinogenic

Keep in mind that these categories only indicate how strong the evidence is that a substance causes cancer. Substances in the same category can differ in how much they increase cancer risk.

Known Substances That Are Carcinogenic to Humans

Sometimes it can be difficult to test and classify substances as carcinogenic to humans, and it isn't ethical to expose people just to see if it causes cancer. Therefore researchers have only been able to classify a little over 100 substances as “carcinogenic to humans.”

Some of the most common group 1 carcinogens are:

Alcoholic beverages
Aluminum production
Arsenic and inorganic arsenic compounds
Asbestos (all forms) and mineral substances (such as talc or vermiculite) that contain asbestos
Coal, indoor emissions from household combustion
Engine exhaust, diesel
Epstein-Barr virus (infection with)
Estrogen postmenopausal therapy
Helicobacter pylori (infection with)
Hepatitis B virus (chronic infection with)
Hepatitis C virus (chronic infection with)
Human immunodeficiency virus type 1 (HIV-1) (infection with)
Human papillomavirus (HPV) (infection with certain types)
Ionizing radiation (all types)
Iron and steel founding (workplace exposure)
Outdoor air pollution
Radon
Tobacco, smokeless
Tobacco smoke, secondhand
Tobacco smoking
Ultraviolet (UV) radiation and ultraviolet-emitting tanning beds

Summary

Carcinogens are substances that can possibly cause cancer due to the damage they cause to DNA inside the cells. DNA tries to repair itself, but sometimes can't because of the problems carcinogens have caused, and ultimately, cancer grows.

The IARC evaluates the carcinogenicity of substances and classifies them based on scientific evidence. More than 100 substances are considered carcinogenic to humans.

Frequently Asked Questions

How long do carcinogens stay in the body?

There is no one specific answer to this question. Some carcinogens leave the body quickly but can cause damage that is long lasting. Other carcinogens may remain in the body for a longer period of time.
How many known carcinogens are there?

According to the IARC, who rates carcinogens, there are 121 known carcinogens to humans.

Originally written by Lisa Fayed

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