What Makes Some Research "Minimal Risk?"

Lead Author(s): Bernard Lo, M.D.

The concept of minimal risk plays a pivotal role in the federal regulations concerning human subjects research. The underlying idea is that minimal risk research requires less oversight than riskier research. The Common Rule treats minimal research differently in several specific ways:

Although minimal risk is an intuitively appealing concept, it is hard to define precisely. According to the Common Rule,

Minimal risk means that the probability and magnitude of harm or discomfort anticipated in the research are not greater in and of themselves than those ordinarily encountered in daily life or during the performance of routine physical or psychological examinations or tests.

Who does "daily life" refer to?

Several key terms in this definition require clarification. First, does "daily life" refer to healthy individuals or to persons who are eligible for the research study? If a study enrolls persons with a serious illness, part of their daily experience as a patient may be invasive procedures such as placement of intravenous lines, bone marrow biopsy, or lumbar puncture. If minimal risk were defined in terms of individuals who are ill, research participants might receive less protection than healthy persons. However, this interpretation is ethically problematic, because persons who already face greater risks in their lives need more protection, not less.

Acceptable risk faced by the general population

Similarly, persons who have socioeconomic disadvantages may face increased risks in their daily lives, such as violence. It would be ethically problematic to allow them to be subjected to greater risks in research simply because they are already disadvantaged. Thus, minimal risks should refer to the common risks that the general population faces - such as crossing the street, getting a blood test, or answering questions on the telephone. Furthermore, the concept of minimal risk involves a normative judgment; society must regard the risk as acceptable, rather than unfortunate or regrettable, as in the case of illness or poverty.

Routine physical examinations or tests

The second part of the definition also requires interpretation. Routine physical examinations or tests should be interpreted to mean studies ordered on annual checkups, such as testing of blood samples obtained by venipuncture, electrocardiograms, or urine analysis. Invasive procedures should not be considered minimal risk, even if they are commonly carried out in patients with the condition being studied.