Minimal Compared With What? How Is the Baseline for Research Risk Determined?

If Research Risk Is “Minimal,” What Is It Minimal Compared With?

Suppose researchers recruit firefighters, patients with advanced illness, people living in a conflict zone, or workers whose occupations routinely expose them to danger. Their ordinary lives may contain risks far greater than those faced by many other people.

Could researchers therefore expose them to correspondingly greater research risks and still call the study “minimal risk”?

This exposes one of the hardest problems hidden inside an apparently simple definition. Many frameworks define minimal risk by comparison with ordinary life or routine examinations. But a comparison requires a baseline, and the choice of baseline can materially change the result.

The Baseline Depends on the Governing Framework and the Comparison It Requires

How the Reference Point for Minimal Risk Is Determined

Minimal Risk Cannot Be Determined in a Vacuum

The word “minimal” is comparative. To decide whether a study meets the threshold, researchers and ethics reviewers need something against which its anticipated harms and discomforts can be judged.

This is why the formal meaning of minimal risk is usually expressed through a comparator rather than a numerical cutoff.

The comparison is useful because ordinary life and routine examinations provide familiar reference points. Yet those reference points are not perfectly uniform. People lead very different lives, undergo different examinations, and face different background risks.

The U.S. Common Rule Uses Daily Life and Routine Examinations or Tests

Under the U.S. Common Rule, minimal risk means that the probability and magnitude of anticipated harm or discomfort are not greater, in themselves, than those ordinarily encountered in daily life or during routine physical or psychological examinations or tests.

The Philippine National Ethical Guidelines for Research Involving Human Participants 2022 define minimal risk using essentially the same comparison.

Notice what the wording does not provide: it does not assign a numerical probability of acceptable harm, nor does it explicitly identify one universal person whose daily life settles every comparison.

Canada Uses a More Participant-Related Daily-Life Comparison

Canada's TCPS 2 defines minimal-risk research as research in which the probability and magnitude of possible harms are no greater than those encountered by participants in those aspects of their everyday lives that relate to the research.

The phrase “that relate to the research” is important. It discourages comparison with arbitrary risks merely because a participant happens to encounter them elsewhere in life.

TCPS 2 also explicitly addresses participants who already face high background risk. It states that research ethics boards have special ethical obligations toward people whose circumstances make them vulnerable and toward those who live with relatively high levels of daily risk. Their inclusion in research should not exacerbate their vulnerability.

Why “Whose Daily Life?” Is Such an Important Question

Imagine two people. One works from home in a relatively safe environment. The other is routinely exposed to physical danger through occupation. If “daily life” simply meant whatever risks each individual already experiences, the second person's dangerous circumstances could create a much higher threshold for research risk.

That creates an ethical problem. Existing disadvantage or exposure to danger could effectively be used to justify imposing risks that would not be considered minimal for others.

A person should not become a convenient candidate for additional research risk merely because life has already given them plenty of it.

Background Risk Is Not Automatically Research Risk

This distinction is central to the baseline problem.

Participants may already face illness, hazardous employment, violence, poverty, environmental exposure, discrimination, or other dangers before they enter a study. Those circumstances matter ethically, but they should not automatically be counted as harms caused by research.

TCPS 2 expressly instructs researchers and REBs to distinguish research-attributable risks from risks participants normally face. It warns against simply compounding research risks with the background risks of people already living in high-risk circumstances.

Keeping these separate helps prevent a dangerous environment from becoming ethical credit that researchers can spend.

Routine Examinations Provide Another Reference Point

The U.S. and Philippine definitions do not rely only on daily life. They also refer to routine physical or psychological examinations or tests.

This provides a useful comparator for some procedures. A research procedure may resemble something people ordinarily encounter during routine examination. But resemblance alone does not settle the analysis.

Researchers should consider what is actually being done, how often, to whom, in what quantity, under what conditions, and with what consequences. A procedure that is routine in one clinical context is not automatically minimal in every research protocol or participant population.

The Comparison Should Be Relevant to the Risk Being Assessed

One should not justify a psychological research risk by pointing to unrelated physical risks people encounter in daily life. Nor does the ordinary risk of driving necessarily provide a meaningful comparator for disclosure of highly sensitive personal information.

CIOMS explains that minimal-risk comparisons are intended to judge research risk by analogy with risks of activities considered acceptable for the relevant population and relatively similar to participating in research.

The underlying logic is comparison, not risk arithmetic. Researchers should look for a reference point that meaningfully resembles the type, probability, and magnitude of the research-related harm rather than simply finding some ordinary activity that happens to be dangerous.

Participant Characteristics Can Still Matter

Avoiding an inflated baseline does not mean pretending participants are interchangeable. Age, health, disability, social circumstances, previous experience, and other contextual factors can change how a research procedure affects someone.

For example, the same procedure may create different physical consequences for a healthy adult and a medically fragile participant. The same disclosure may have different consequences for people living under different legal or social conditions.

Ethical analysis therefore has to hold two ideas together: participant characteristics can affect actual research risk, but unusually risky circumstances should not automatically raise the amount of research-attributable risk considered minimal.

The Baseline Is Not a License to Ignore Risk Minimization

Even when a proposed activity falls within an applicable minimal-risk threshold, researchers should still ask whether its risks can reasonably be reduced.

Risk classification and risk minimization answer different questions. Classification asks where the study sits relative to a threshold. Minimization asks whether unnecessary exposure remains in the protocol.

This is why determining that a study is minimal risk does not replace the broader question of whether its remaining risks are ethically acceptable.

The Baseline Can Have Real Procedural Consequences

This is not merely a philosophical argument about terminology. In many ethics systems, minimal-risk determinations affect review pathways and other regulatory provisions.

Canada's TCPS 2, for example, generally permits delegated review of minimal-risk research while requiring full-board review for above-minimal-risk research. Under the U.S. Common Rule, certain categories of research involving no more than minimal risk may qualify for expedited review.

In the Philippines, the classification also has practical significance. The 2022 National Ethical Guidelines use minimal risk in provisions concerning ethics review and certain consent waivers, while PHREB accreditation levels can affect what kinds of protocols an accredited research ethics committee is authorized to review.

Choosing the comparator carelessly can therefore affect more than wording in a protocol. It can influence how research is reviewed and what protections are considered necessary.

Can a Dangerous Occupation Raise the Minimal-Risk Baseline?

The key distinction is subtle but important. Participant circumstances may alter the actual risk of a research procedure without necessarily providing a higher ethical ceiling for what researchers may call minimal.

Common Mistakes When Choosing a Minimal-Risk Baseline

Choose the Baseline From the Applicable Framework, Not From Convenience

If your protocol describes a study as minimal risk, make the comparison visible. State the governing definition, identify the research-attributable harms, and explain why their probability and magnitude do not exceed the relevant threshold.

This approach may feel less tidy than simply checking a “minimal risk” box, but the untidiness is real. The comparator is part of the ethical argument, not administrative fine print.

Before Applying a Minimal-Risk Baseline, Check These

Frequently Asked Questions About the Minimal-Risk Baseline

The Baseline Is Part of the Minimal-Risk Judgment

How to Cite This Guide

This guide is intended to be read, shared, and used in research, teaching, and academic work. If you draw on its ideas, explanations, or other content, please acknowledge the source by citing the guide. Doing so gives appropriate credit and helps your readers locate the original resource.