10th March, 2021

What Is A Carcinogen?

Employers have a legal duty to protect workers from harm, including the health effects of hazardous substances and materials. Carcinogens in your workplace could put your team at risk of developing cancer, so it's important to identify, prevent and control exposure to keep people safe.

What Is A Carcinogen? header image

A carcinogen is something known or suspected of causing cancer. A carcinogen could be a substance or material that, when it comes into contact with the human body, causes abnormal development of body cells. These abnormal cells become cancers. Put simply, the Cambridge Dictionary gives the definition of a carcinogen as 'a substance that can cause cancer'.

Cancer can be caused by substances, or mixtures of substances, called 'carcinogens’. Occupational cancer can be caused through prolonged exposure to carcinogens in the workplace.

A carcinogen could be dust, fume, liquid, solid, vapour or gas. It may be harmful to humans in one form, but not another. Not all carcinogens are the same or have the same risks, and exposure can be through different routes. Most commonly, exposure (and harm) is inhalation, but some carcinogens can also be absorbed through skin contact, or ingested. Some carcinogens have more potential to cause cancer than others. At work, suitable controls should be put in place to protect people from the exposure risks they face.

Examples of carcinogens at work

There are lots of substances and materials that are known to cause cancer, and some of these can be present or used in the workplace. Examples include:

The most well-known carcinogen at work is asbestos. Although it’s known as the hidden killer, it’s no secret that asbestos exposure is dangerous. In fact, asbestos was completely banned in 1999. However, it remains a risk to workers because it was used so heavily in past, and can still be found in many buildings.

Other carcinogenic materials, like silica and wood, are still in use. These materials are often considered safe, which they can be if the correct precautions are taken.

wood dust

How do you know if a material or substance is a carcinogen?

To comply with COSHH, you should identify and assess any hazardous substances used or produced in your work processes. Identifying carcinogens used within your business is straight forward enough because this information will be readily available on packaging and information material datasheets.

For carcinogens that are known or presumed to cause cancer, the material data sheet will carry the hazard statement ‘may cause cancer’. These substances will also carry the serious health hazards CLP symbol.

For substances and materials that are suspected of causing cancer, these carry the hazard statement ‘suspected of causing cancer’. They will display the health hazards CLP symbol.

You should also consider the dust and fumes you produce during work activities, considering the materials and processes used to determine if any hazardous carcinogenic dust or fumes are created. For example, while you can no longer buy asbestos materials for use, drilling into a wall or material could expose the worker to asbestos fibres if the material being drilled contained asbestos.

dust cloud

What do you need to do about carcinogens?

Employers have health and safety legal duties, to protect their workers and others that may be affected by the work. Just like safety hazards, health hazards must also be controlled, so that people don’t come to harm at work. Specifically, for dangerous and hazardous substances, there is a set of regulations that apply. The Control of Substances Hazardous to Health Regulations (COSHH).

“carcinogen” means—

  1. a substance or preparation which if classified in accordance with the classification provided for by regulation 4 of the CHIP Regulations would be in the category of danger, carcinogenic (category 1) or carcinogenic (category 2) whether or not the substance or preparation would be required to be classified under those Regulations; or
  2. a substance or preparation— i) listed in Schedule 1, or ii) arising from a process specified in Schedule 1 which is a substance hazardous to health;
The Control of Substances Hazardous to Health Regulations 2002 Interpretation

The COSHH regulations require employers to assess the health risks created at work where employees are exposed to hazardous substances and to prevent or control exposure to safe levels. This can be done through a process known as COSHH assessment. The COSHH regulations apply to all substances hazardous to health, not just carcinogens.

In addition to COSHH, some substances even have their own regulations, like The Control of Asbestos Regulations.

dust exposure

Because of the health risks involved, a workplace exposure limit (WEL) may be assigned to a substance. Workplace exposure limits (WELs) are assigned to a large number of hazardous substances. Exposure limits are in place to control the effects of harmful substances, depending on the nature of the substance and the effects of exposure. Legally this exposure limit must not be exceeded. Around 500 substances have WELs assigned to them, and these hazardous substances include carcinogens.

In all cases, the use or exposure to hazardous substances, like carcinogens, at work must be identified, assessed, controlled and monitored. Employees should be provided with instruction and training for them to know the health risks and the precautions needed to be taken to keep them safe.


Find out more about COSHH assessments, the law and legal responsibilities, or browse through the ready to use COSHH assessment templates.

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This article was written by Emma at HASpod. Emma has over 10 years experience in health and safety and BSc (Hons) Construction Management. She is NEBOSH qualified and Tech IOSH.

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