Table 1.
Internationally agreed testing methods for carcinogenicity.
| Test method |
OECD test guideline | Species/number | Objective of the study | Duration of the study |
|---|---|---|---|---|
| Carcinogenicity studies | TG. 451 | Rats and mice (50–65/sex/group) Non-rodents (mainly dog) (4–6/sex/group) |
Observe test animals for a major portion of their life span for the development of neoplastic lesions during or after exposure to various doses of a test substance | Normally 24 months for rodents. For specific strains of mice, duration of 18 months may be more appropriate. |
| Combined chronic toxicity/ carcinogenicity studies |
TG. 453 | Rat (10/sex/group) chronic phase; and (50/sex/group) carcinogenicity phase | Identify carcinogenic and the majority of chronic effects and determine dose-response relationships following prolonged and repeated exposure. | Normally 12 months for the chronic phase, and 24 months for the carcinogenicity phase. |
| Chronic toxicity studiesa | TG. 452 | Rodents (20/sex/group) and non-rodents (4/sex/group) | Characterise the profile of a substance in a mammalian species following prolonged and repeated exposure. | Normally 12 months but, 6- or 9-month-studies are also performed. |
Internationally agreed testing methods for carcinogenicity. Data were retrieved from the OECD website. The above methods are used by industry and governments for the regulatory safety testing of carcinogenic potential of chemicals.
a
The chronic toxicity study is not aimed specifically at testing carcinogenicity, but it can be used for early detection of neoplastic lesions (Madia et al., 2016).