Toxicokinetics (often abbreviated as 'TK') is the description of what rate a chemical will enter the body and what happens to it once it is in the body. It is an application of pharmacokinetics to determine the relationship between the systemic exposure of a compound in experimental animals and its toxicity. It is used primarily for establishing relationships between exposures in toxicology experiments in animals and the corresponding exposures in humans. However, it can also be used in environmental risk assessments in order to determine the potential effects of releasing chemicals into the environment, and where a chemical would be expected to end up once it is in the environment (e.g. within animals, water, air, plants, or soil).