X-rays Considered for Carcinogen List

Paraphrased by Steve Waldrop
January 13, 2003

The federal government has begun evaluating whether medical X-rays should be declared a carcinogen, a move that experts say could reduce unnecessary exposures to radiation and force doctors to pay closer attention to the risks involved.

The evaluation, which will be conducted over the next year, was prompted by a request from the National Institute of Environmental Health Sciences. The listing is being considered for the National Toxicology Program's 11th Report on Carcinogens due in 2004.

Cancer risks from radiation exposure are well documented in studies of atomic bomb survivors, but risks from medical sources are controversial and often down- played by physicians.

"There is a lot of data showing that radiation is a carcinogen at very high levels," said G. Donald Frey of the American Association of Physicists in Medicine. "What is scientifically unsettled is whether it causes cancer at low levels. We don't really absolutely know."

According to the National Cancer Institute, major organizations "agree there probably is no low-dose radiation "threshold" for inducing cancer, i.e., no amount of radiation should be considered absolutely safe."

The NIEHS is concerned that use of Computed Tomography (CT) scans, fluoroscopy, mammography in younger women and medical X-rays are exposing the public to increasingly higher levels of radiations, says its director, Christopher Portier.

Fred Mettler, a spokesman for the American College of Radiology and professor of radiology at the University of New Mexico, says radiologists are supposed to "optimize" radiation doses by exposing patients only to enough radiation to get a clear image. The risk of exposure is balanced against the medical benefit.

A CT scan is equal to 100 chest X-rays. For every 1 million children scanned with CT, an estimated 1,500 will develop cancer two decades later. Up to 3 million children receive CT scans each year. Children are typically given adult doses during CT scans.

Last October, The NCI issued an alert to radiologists asking them to lower CT doses to children.