Chronic Toxicity and Carcinogenicity Testing

In a chronic toxicity test, repeated exposures are continued for six months or longer. The duration of a chronic toxicity test depends on the anticipated duration of human exposure relative to the human life cycle. Eor example, if the chemical is a food additive to which humans may be exposed throughout their adult life, the chronic toxicity test is designed to last the adult life span of the test species, about two years in mice and two-and-a-half years in rats. 

Essentials of Toxic Chemical Risk Science and Society 

The test animals are monitored closely for signs of toxicity, and blood samples are collected regularly. Autopsies are performed on animals that die in the course of the study. Animals that survive the study are sacrificed and autopsied. Chronic toxicity testing provides further insight into the pathology(ies) and mechanism(s) of disease caused by exposure to a toxic chemical. It establishes a relationship between the degree of exposure to a chemical and the frequency with which a toxic endpoint such as cancer is manifested in the exposed population. 

---

Chronic toxicity and carcinogenicity tests on rats (2 years) and mice (18 months)... 

The tests for external devices contacting blood are also the same as for implanted devices, although implantation tests are noted as may be applicable. For long-term devices, either external or implants, chronic toxicity and carcinogenicity testing may also be required. 

---