Rout of test compound administration
Toxicity testing in animal models is most useful if it imitates the human or domestic/farm animal route of exposure to chemical agents. Based on the medium of exposure in human and domestic animals, it is possible to decide which is the administration route of choice in animal toxicological tests (table5.2). Depending on the route of administration, experimental evaluation may differ because of variation in the absorption, metabolism and elimination of a compound. Oral exposure can lead to absorptionby the digestive system and metabolism by the livers, whereas, following inhalation, a toxic compound os more likely to be absorbed by the respiratory system. Metabolism of xenobiotic can also occur in placenta, in the test dam and fetus. This can lead to changes in the balance of parent compound and metabolites, complicating the picture even more in case of development toxicity tests.