Final answer:
In human subject research, the two key ethical concepts are informed consent and confidentiality, which are vital for participant safety and privacy, and are overseen by Institutional Review Boards.
Step-by-step explanation:
The two key concepts regarding ethical recruitment and participation of human subjects in human subject research are informed consent and confidentiality. Informed consent ensures that participants are fully aware of the research and any associated risks before agreeing to partake. Confidentiality pertains to safeguarding the privacy and personal information of the participants throughout and after the research process. These two principles are fundamental to ethical research and are enforced by Institutional Review Boards (IRBs), which review and approve research proposals to ascertain adherence to ethical standards.