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GHS Classification Criteria for Carcinogenicity

Little Pro on 2018-05-08

A carcinogen refers to a chemical substance or a mixture of chemical substances which induce cancer or increase its incidence rate. Substances which have induced benign and malignant tumours in well performed experimental studies on animals are considered also to be presumed or suspected human carcinogens unless there is strong evidence that the mechanism of tumour formation is not relevant for humans.

GHS Classification Criteria for Carcinogenicity

There are 3 hazard categories for carcinogenicity under GHS.

Category Criteria
Category 1A Known to have carcinogenic potential for humans.
  • Largly based on evidence from humans.
Category 1B  Presumed human carcinogens
  • Largly based on well performed animal studies.
Category 2 Suspected human carcinogens
  • The placing of a chemical in Category 2 is done on the basis of evidence obtained from human and/or animal studies, but which is not sufficiently convincing to place the chemical in Category 1

US OSHA Guidance on GHS Carcinogenicity Classification

US OSHA has further provided guidance on GHS carcinogenicity classification based on animal studies. We have summarized the key points here.

  • Chemicals with positive outcomes in two or more species would be provisionally considered to be classified in GHS Category 1B until human relevance of animal results are assessed in their entirety.
  • Positive results for one species in at least two independent studies, or a single positive study showing unusually strong evidence of malignancy may also lead to Category 1B. 
  • If tumors are seen only in one sex of an animal species, the mode of action should be carefully evaluated to see if the response is consistent with the postulated mode of action. Effects seen only in one sex in a test species may be less convincing than effects seen in both sexes.
  • Tumors occurring only at excessive doses associated with severe toxicity generally have doubtful potential for carcinogenicity in humans. In addition, tumors occurring only at sites of contact and/or only at excessive doses need to be carefully evaluated for human relevance for carcinogenic hazard.

GHS Carcinogenicity Classification Criteria for Mixture

GHS classification criteria carcinogen

Read more: comparison of GHS concentration limits for carcinogenicity

References and More Reading

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