Toxicity studies: Chronic

The chronic toxicity study provides information on possible health hazards likely to arise from repeated exposure over a considerable part of test species' lifespan. 

Studies provide data about toxic effects of a substance, indicate target organs and the possibility of accumulation. They can also provide estimates of no-observed-adverse effect levels to help establish safety criteria for human exposure. 

Test duration ranges from 26 to 52 weeks, depending on test species. The majority of chronic toxicity studies are carried out in rodent species, but NHP are also used. 

The three main routes of administration used in chronic toxicity studies are oral, dermal and inhaled. The choice of the route depends on the physical and chemical characteristics of the test chemical and the predominant route of exposure in humans.