Health and Safety


There are specific requirements under the COSHH Regulations concerning working with Carcinogens, Mutagens and Substances Toxic to Reproduction (STRs). The group is generally referred to as CMR. A summary is given below and further detail is contained within University Guidance PDF format.


Carcinogens are divided into three categories (as per the statutory requirements under the Classification, Labelling and Packaging (CLP) of Substances and Mixtures Regulations:

    • Category 1A (previously Cat 1) - substances known to have a carcinogenic potential for humans based largely on human evidence.
    • Category 1B (previously Cat 2) - substances presumed to have a carcinogenic potential for humans based largely on animal evidence.
    • Category 2 (previously Cat 3) - suspected human carcinogens based on human and animal evidence but which is not sufficiently convincing to place the substance in Cat 1.

Categories 1a and 1b, if purchased from a supplier, will carry the Hazard Statements H350 (previously R45) - "may cause cancer" or H350i (previously R49) "may cause cancer by inhalation" and the "serious health hazard" symbol (see below). These are subject to specific control under COSHH.

Category 2, if purchased from a supplier, will carry the Hazard Statement H351 (previously R40) - "Suspected of causing cancer" and will carry the "health hazard" symbol. These are not included in the COSHH definition of a carcinogen but are subject to the general requirements of COSHH.

Mutagens and STRs

Mutagens are substances that cause heritable genetic changes (mutations). Most mutations are harmful and most mutagens are carcinogens and vice versa. Substances that are known to impair fertility or to cause developmental toxicity in humans are defined as Toxic to Reproduction. (STR). This definition covers a broader range of health effects than the earlier "teratogenic" which applied only to substances that adversely affected the developing foetus.

Mutagens and STRs are classified similarly to Carcinogens in Categories 1A, 1B and 2.

    • Category 1A and 1B Mutagens carry the Hazard Statement H340 (previously R46) - "May cause genetic effectts" and Category 1A and 1B STRs carry the Hazard Statement H360 (previously R60/R61) - "May damage the unborn child/impair fertility".
    • Category 2 Mutagens have the Hazard Statement H360 (previously R68) - "Suspected of causing genetic defects" and Category 2 STRs are classified by H361 (previously R62/R63) - "Suspected of damaaging fertility/the unborn child".

These substances, unlike carcinogens, are not specifically prescribed in COSHH. However, because of the nature of the hazard, workers should adopt the precautions and principles outlined in this section.

As with any other hazardous substance, a risk assessment must be carried out for the procedure involving the use of a CMR. The risk assessment must identify the means by which exposure can be prevented or if not reasonably practicably controlled.

Strategy for Controlling Exposure

Prevention of exposure can be achieved through substituting with a less harmful substance, modifying the process to avoid using the carcinogen, or avoiding the formation of carcinogenic by-products or intermediates. Where this is not reasonably practicable the University guidance must be followed in terms of the strategy for controlling exposure.


Health and Safety Department

Pharmacy Building (Building 63)
University Park
University of Nottingham
Nottingham, NG7 2RD

Telephone: Telephone: +44 (0)115 9513401
Email: h&