This document discusses various types of long-term toxicity tests for drugs, including allergenicity/hypersensitivity tests using guinea pigs, genotoxicity studies looking for early cancer effects using bacterial and mammalian cell assays, in vivo chromosomal damage tests in rodents, carcinogenicity/oncogenicity lifetime bioassays in animals, and teratogenicity studies to assess a drug's ability to cause birth defects when administered to a pregnant mother, which can occur during three stages of fetal development. The type and timing of any fetal exposure depends on the drug's pharmacokinetics in the maternal system.