Fear-Mongering Where It Hurts the Most

"Each year, about 1.6 million children in the U.S.A. get CT [computed tomography] scans to the head and abdomen — and about 1,500 of those will die later in life of radiation-induced cancer," reported USA Today recently.

NBC's Today Show news anchor Ann Curry teased viewers: "We're going to talk to one of the authors of the study. It's very — very important information and very scary for parents."

The scary media reports worked. Physicians were overwhelmed with questions from anxious parents.

The alarming news in question was based on a new study published in the American Journal of Roentgenology.

But the study and accompanying news reports distorted the science and sensationalized the risk, and may have done more harm to childrens' health than CT scans ever will.

CT scans have been used since the 1970s. They employ low levels of radiation to help diagnose cancers, appendicitis, kidney stones, trauma and other conditions.

Despite common use, no person is known to have developed cancer from a CT scan and no study reports an increase in cancer rate among individuals who have undergone CT scans.

In the study cited by USA Today and Ann Currie, the researchers derived their conclusions by statistical extrapolation from data collected about the Japanese survivors of the atomic bomb blasts at Hiroshima and Nagasaki.

Scientists agree that exposure to sufficiently high levels of radiation increases cancer risk — slightly. Among the more than 86,000 survivors of the atomic bomb blasts, about 420 "extra" cancers occurred between 1950 and 1990.

The level of radiation exposure at which a statistically significant increase in cancer is observed among the atomic bomb survivors is about 350 milliSieverts (a Sievert is a unit for measuring the biological effect of ionizing radiation). Below this level, no clear increase in cancer rates has been observed.

The levels of radiation exposure from CT scans used in the study range from about 10 milliSieverts to about 130 milliSieverts. These levels are well below those associated with a slight increase in cancer among the atomic bomb survivors.

Moreover, the radiation levels used in the study were obtained from 15-year-old CT technology that generated twice as much radiation as today's CT technology.

Based on hard data, therefore, radiation exposures from CT scans are well below what is known to be associated with a slight increase in cancer among the atomic bomb survivors. The authors of the study couldn't cite one case of cancer tied to CT scans. They played fast and loose with the numbers, and put us all at risk as a result.

These researchers, and others like them, insist on assuming that any "extra" exposure to radiation increases cancer risk. Mathematical models based on this assumption statistically project increases in cancer from the atomic-bomb survivor data down to virtually any radiation exposure above that encountered naturally in the environment.

Though these models remain invalidated by real-world data and are quite controversial, such a model was used to predict potential cancer deaths from CT scans. The prediction is strictly speculative and not based on any actual data despite much use of, and experience with, radiation for medical and non-medical purposes.

While there is no factual basis for concern about radiation risk from CT scans, there is cause for concern about the unwarranted fear spread by the researchers and media.

CT is a leading diagnostic tool to aid in the early detection of cancer. CT scans are only used when children are seriously ill or injured or when a physician suspects a serious medical problem.

CT scans allow more than 500,000 children to avoid exploratory surgeries each year in the U.S. Since the introduction of CT technology, the death rate from childhood cancer has been cut in half.

Radiologists balance the need for high-quality images with the goal of keeping radiation doses as low as reasonably possible. The American College of Radiology is in the final stages of testing its new CT Facility Accreditation Program that has this balance in mind.

Responsible researchers shouldn't use non-scientific predictions to scare parents about a medical procedure that could help save children's lives.

Responsible media shouldn't parrot alarming research claims, especially without providing any balance. Neither USA Today nor Today presented contrary views of the study.

We're fortunate to have CT technology. If we're overexposed to anything, it's junk science and shoddy reporting.

— Steven Milloy is a biostatistician, lawyer and adjunct scholar at the Cato Institute and publisher of Junkscience.com.