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What are Carcinogens, Mutagens and Reprotoxic Substances ?

Words associated with mutagens

What is a Carcinogen?

Carcinogen means a substance or a mixture of substances which induce cancer or increase its incidence.

In the CMRS Regulations, a carcinogen is :

(a) a substance or mixture which meets the criteria for classification as a category 1A or 1B carcinogen set out in Annex I to Regulation (EC) No. 1272/2008 of the European Parliament and of the Council (CLP Regulations - the Classification, Labelling and Packaging Regulations)

(b) a substance, mixture or process referred to in Annex I to the Directive (CMD as amended) as well as a substance or mixture released by a process referred to in Schedule 4 of the COP 

What is a Mutagen?

A mutation means a permanent change in the amount or structure of the genetic material in a cell. A mutagen is an agent which gives rise to an increased occurrence of mutations.

In the CMRS Regulations, a mutagen is a substance or mixture which meets the criteria for classification as a category 1A or 1B germ cell mutagen set out in Annex I to Regulation (EC) No. 1272/2008 (CLP).

What is a Reprotoxic Substance?

Reproductive toxicity includes adverse effects on sexual function and fertility in adult males and females as well as development toxicity in the offspring. Reprotoxic substance can damage the reproductive process.

In the CMRS Regulations, a reprotoxic substance is a substance or mixture which meets the criteria for classification as a category 1A or 1B reproductive toxicant set out in Annex I to Regulation (EC) No. 1272/2008 (CLP).

Under CMRS these can be subdivided

  • (a) “non-threshold reprotoxic substances” for which there is no safe level of exposure for employees’ health, and which is identified as such in the Code of Practice; or
  •  (b) “threshold reprotoxic substances” for which a safe level of exposure exists below which there is no risk to employees’ health, and which is identified as such in the Code of Practice;

Many substances classified as reprotoxic substances are not yet subdivided into either of these categories. 

How do I know if the substance or mixture is a ‘carcinogen’ or "mutagen" or a “reprotoxic substance”

  1. Check the label and safety data sheet (SDS) for the substance or mixture to determine whether or not the material is carcinogenic or mutagenic.  Look out for the following:

     Classification          Code        Hazard Statement

    • Carc 1A, 1B     H350       May cause cancer
    • Carc 1A, 1B     H350i      May cause cancer by inhalation
    • Muta 1A, 1B    H340       May cause genetic defects

    • Repro 1A, 1B   H360      May damage fertility or the unborn child.

  2. Check Schedule 4 of the 2024 Code of Practice

  3. Hazardous medicinal products (HMP) are medicinal products that contain one or more substances that meet the criteria for classification of carcinogenic, mutagenic or toxic for reproduction in accordance with Regulation (EC)No 1272/2008 (the CLP Regulation). They include medicinal products for both human and veterinary use. HMPs can be identified by inspecting the labels on the packaging. For cytotoxic medicines, the symbols are often purple or yellow and include a representation of a cell in telophase or a Yellow Hand. See HSA Newsletter, guidance for the safe management of hazardous medicinal products and an Indicative list of hazardous medicinal products from the European Commission.
How are Carcinogens, Mutagens and Reprotoxic Substances classified?

Carcinogenic, mutagenic and reprotoxic substances are classified into a number of categories under the CLP Regulations: 

  • A category 1 carcinogen is a known or presumed human carcinogen
    • Carc 1A are known to have carcinogenic potential for humans and is largely based on human evidence
    • Carc 1B are presumed to have carcinogenic potential for humans ,classification is largely based on animal evidence.
  • A category 1 mutagen  is a substance known to induce heritable genetic mutations or to be regarded as if they induce heritable mutations in the germ cells of humans.
    • Muta 1A classification is based on positive evidence from human epidemiological studies.
    • Muta1B classification is based on positive mutagenicity test results on cells in humans.
  • A category 1reproductive toxicant is a know or presumed human reproductive toxicant
    • A reprotoxic substance  (Repro 1A) is a substance known to be toxic for human reproduction . The classification is largely based on evidence form humans.
    • A category 1B  reprotoxic substance  (repro 1B) is a presumed human reproductive toxicant. The classification is based on data from animal studies
Are there any other categories?

A third category of carcinogen/mutagen/reprotoxic substance exists and while these fall outside the specific scope of the carcinogen regulations they must still be  risk assessed under the Chemical Agents Regulations and the Safety. Health and Welfare at Work Act, 2005

  • Category 2 carcinogens are suspected human carcinogens. This is based on evidence obtained from human and/or animal studies but which is not sufficient for a Category 1 classification
  • Category 2 mutagens cause concern for human owing to the possibility that they may induce heritable mutations in the germ cells of humans.
  • Category 2 reprotoxic substance are suspected human reproductive toxicants. There is some evidence from studies which is not sufficient for a Category 1 classification

 Category 2 substances and mixtures should be labelled:

  • Classification    Code        Hazard Statement
  • Carc 2              H351       Suspected of causing cancer
  • Muta 2             H341       Suspected of causing genetic defects.
  • Repro 2          H361      Suspected of damaging fertility or the unborn child