 The process of testing potential new treatments can take 10–15 years, and is standardly divided into phases. Formalized phase 0 studies are a relatively recent phenomenon involving the testing of interventions and methods which might be used in later phase studies. A phase 0 study might be designed to determine the mechanism of action of a particular drug and evaluate different ways to administer it. Phase 1 studies are the earliest tests of a new intervention and are conducted in small numbers of individuals. Phase 1 studies are designed to evaluate the pharmacokinetics and pharmacodynamics of new treatments, essentially evaluating how the drug influences the human body and how the human body influences the drug. Phase 1 studies also evaluate the risks of the treatment and attempt to identify an appropriate dose to be used in subsequent phase 2 studies. Phase 1 studies pose risks and frequently offer little if any potential for clinical benefit to participants. As a result, a significant amount of the ethical concern over clinical research focuses on phase 1 studies.