Experiments on human subjects and animals should follow the ethical standards set out in the Helsinki Declaration of 1975 (revised by the World Medical Association in Edinburgh in 2000), which led to the establishment of ethics committees. These guidelines ensure the welfare of the animals or human subjects involved in research and require that human subjects provide informed consent for any experiments. That is, human subjects are to be informed of the purpose and nature of the experiments and consent to being subject to them. All research using human and animal subjects must comply with the Helsinki Declaration. If not, the researchers must explain the rationale underlying their approach and obtain approval from a local or institutional ethical review body.