Vulnerable populations can be defined as children, prisoners, pregnant women, handicapped or mentally disabled persons, or economically or educationally disadvantaged persons. If vulnerable individuals are involved in clinical trials, IRBs must ensure that additional safeguards have been included to protect the vulnerable group. Safeguards may include the presence of interpreters or social workers to explain the research and ensure informed consent. IRBs have a specific obligation to protect those individuals who are particularly susceptible to coercion or undue influence (21 CFR 56.11). Studies involving vulnerable groups often pose difficult ethical questions. For example, vulnerable subjects may not be allowed to participate in research that involves more than minimal risk but conveys no benefits directly to the subjects. (21 CFR 56.11 and 45 CFR 46 Subparts B, C, D).