A carcinogen is a substance or agent that can cause cancer or it increases the risk of developing cancer. Known carcinogens include viruses (e.g. Hepatitis B), hormones (e.g. estrogens), chemicals (e.g. benzene), naturally occurring minerals (e.g. asbestos), alcohol, and solar radiation (e.g. ultraviolet radiation).
Occupational cancer is cancer that is caused wholly or partly by exposure to a carcinogen at work.
Research shows that the amount of cancer related to occupational exposure varies with the type of cancer. The most common types of occupational cancer are lung cancer, bladder cancer and mesothelioma.
|Type of Cancer||Related to Occupational Exposure|
Estimated % (USA)
|Mesothelioma||85-90% (men); |
|Skin Cancer (non-melanoma)||1.5-6% (men)|
|Sinonasal and nasopharyngeal||31-43% (men)|
|Liver||0.4-1.1 (vinyl chloride only; men)|
* In general, the overall attributable risk for mesothelioma in women is 23%. However, if the woman has had "take-home" exposure to asbestos, the risk may be around 90%. "Take-home" exposure results from asbestos being carried home on contaminated work clothing or other items.
Data From: Steenland, K., et al. Dying for work: the magnitude of US mortality from selected causes of death associated with occupation. American Journal of Occupational Medicine. Vol. 43 (2003). p. 461-482
Scientists identify cancer-causing agents using information from:
Scientists generally use information or evidence from all of these sources when determining if an agent can cause cancer.
Identifying carcinogens is complicated. Fortunately, there are several organizations that evaluate the available information according to specific criteria.
The most authoritative lists of carcinogens are published by the:
IARC classifies each agent or exposure into one of five groups according to the strength of scientific evidence for carcinogenicity, as follows:
A list is available at the IARC Monographs web site.
ACGIH assigns each chemical or agent to one of the following 5 categories:
Carcinogens identified by ACGIH are listed in ACGIH's TLVs® and BEIs® booklet that is published annually. See the ACGIH web site for more information.
NTP publishes a biennial list of agents that they have evaluated and assigned to one of two categories:
Their 12th Report on Carcinogens is available online.
Examples of occupations and occupational groups that have been associated with occupational cancer are listed in the following table Occupations or Occupational Groups Associated with Carcinogen Exposure.
In many cases, certain types of cancer are associated with specific carcinogens. Our OSH Answers document Cancer Sites Associated with Occupational Exposures has a list of examples.
Many Canadian jurisdictions do regulate workplace exposures to carcinogens (e.g. asbestos). The specific substances regulated and regulatory requirements vary by jurisdiction. Regulations typically specify maximum exposure limits. In some cases, the regulations may require routine monitoring of the workplace, medical surveillance of workers, specific record keeping, etc.
Check with your local department or ministry responsible for occupational health and safety for more information.
In Canada, the Workplace Hazardous Materials Information System (WHMIS) is a nation-wide system that ensures people have the information they need to work safely with hazardous products (including carcinogens) in the workplace.
Agents on the following lists are classified as WHMIS carcinogens:
These products are included in the WHMIS category D2: Class D - Poisonous and Infectious materials - Division 2: Materials Causing Other Toxic Effects. The symbol used on the products is the stylized "T".
WHMIS requires that people who work with hazardous products have training about the potential hazards of the products and how to work with them safely. Information on the classification and how to work safely with that product is included on the Material Safety Data Sheets (MSDSs).
There are many ways to control the hazards of any substance or agent.
A hazard control program consists of all steps necessary to protect workers from exposure to a substance or system, and the procedures required to monitor worker exposure and their health to hazards such as chemicals, materials or substance.
Knowing which control method is best can be a complicated process. It often involves doing a risk assessment to evaluate and prioritize the hazards and risks.
For more information, please see the following documents in OSH Answers:
The following general advice can help you work safely with a carcinogen:
Reducing exposure will reduce your risk of developing cancer from exposure to a carcinogen.
Typically, there are 3 important routes of exposure in a workplace setting — inhalation, skin contact and ingestion. In addition, there are several factors that can influence how likely a substance is to cause a specific effect (e.g. cancer), for example.
When considering if a person may have been exposed to a chemical, or if measures are being taken to reduce exposures currently in the workplace, there are many questions that should be asked. Some include:
Another important factor is how long and how much a person was exposed to the agent. Duration (how long) of exposure to some agents may be infrequent or only in very small amounts, while others may be used daily or in very large amounts. The number of weeks or years on the job may provide an estimate of the degree of exposure. In general, the higher the exposure (duration and/or amount), the higher the risk of developing a health effect, including cancer.
For more information on how substances enter the body or how they are poisonous, and related topics, please see our other OSH Answer documents:
There are many organizations that can provide assistance for people with cancers. These are just a few* that mention occupational cancers specifically.
(*We have mentioned these organizations as a means of providing a potentially useful referral. You should contact the organization(s) directly for more information about their services. Please note that mention of these organizations does not represent a recommendation or endorsement by CCOHS of these organizations over others of which you may be aware.)
Document last updated on March 3, 2008