Answer to Question #5563 Submitted to "Ask the Experts"

Q

The Food and Drug Administration has set a level of 0.5 mrem per hour as the standard as considered safe for exposure. I recently read a report from John W. Gofman, MD, PhD, of the Committee for Nuclear Responsibility. He claims that there is no level of radiation that is completely safe. He claims that the only risk-free (safe) dose is zero dose. This opinion is supported by the United Nations Scientific Committee on Effects of Atomic Radiation and Britain's National Radiological Protection Board. What is the Health Physics Society's position on this matter?

A

There are several scientific bodies that support what is referred to as the linear no-threshold (LNT) radiation dose-risk theory. This theory is that any radiation dose carries some level of risk, hence Dr. Gofman's suggestion that the only safe dose is zero dose.

The true implication of the LNT theory is that low doses are low risk. Much as driving 55 mph is considered lower risk than driving 80 mph, lower radiation doses are considered lower risk than higher radiation doses. There is a point when the risks of anything we encounter in our lives is so low that we accept them or consider them safe, even though we are aware of the risk. There is very little we do in our daily life that in some manner does not carry a risk.

The Health Physics Society doesn't speak directly to so-called "safe" radiation exposure levels. It does have a position statement on Risk Assessment and one titled Radiation Risk in Perspective. The first includes the following statement: "Below 5-10 rem, risks of health effects are either too small to be detected or nonexistent." The other states: "Cancer and other health effects have not been observed consistently at low doses (10 rem) because the existence of a risk is so low as to not be detectable by current epidemiological data and methods."

The most recent report out from the Biological Effects of Ionizing Radiation Committee (a group also supporting the LNT theory; BEIR VII) has indicated that, even with the most recent science taken into account, we are unable to determine with certainty what the dose-risk curve looks like below 2 rem because radiogenic effects simply are not detectable in a human below that level.

Kelly Classic
Certified Medical Health Physicist