The Environmental Protection Agency has caused a commotion in the medical imaging community over proposed rule changes that some perceive as leading toward a weakening of regulations around radiation exposure.

The government agency is questioning current, decades-old guidelines based on the notion that any exposure to radiation places individuals at greater risk of developing cancer in their lifetime. The argument to revisit these guidelines is based on scientific outliers claiming that exposure to small doses of radiation can actually be good for humans.

The EPA's suggestion has been met with condemnation from numerous individuals and organizations that fear alterations may place medical workers as well as nuclear workers and others at risk of exposure to larger amounts in their environment.

“The American Society of Radiologic Technologists is committed to optimal patient care that includes a focus on protection from unnecessary medical radiation,” Greg Morrison, ASRT associate executive director, told HCB News. “We strongly oppose any measure that would weaken radiation protection measures for patients, radiologic technologists and all other healthcare workers.”

Medical and scientific communities currently operate under the linear no-threshold model, which claims that no threshold of risk-free radiation exposure exists. Supporters of the proposal claim the model is flawed and has led to unnecessary spending for managing exposure in accidents, at nuclear plants, in medical facilities and at other sites.

First introduced in April, the Strengthening Transparency in Regulatory Science proposal directs regulators to consider alternative scientific viewpoints when establishing or adhering to regulatory standards, including evaluating various threshold models across the range of exposures when in contact with dangerous substances.

Though it does not specifically mention radiation, many interpret its wording to include radiation protection standards. Edward Calabrese, a toxologist at the University of Massachusetts who supports the proposal, has called it “a major scientific step forward” that would save billions and have a positive impact on human health.

Echoing this sentiment was Brant Ulsh, a physicist with the California-based consulting firm M.H. Chew and Associates. “Right now we spend an enormous effort trying to minimize low doses” he told the Associated Press. “Instead, let’s spend the resources on minimizing the effect of a really big event.”

Others, though, disagree, basing their views on scientific literature that supports continued use of the LNT model for radiation protection. The National Council on Radiation Protection and Measurements recently reaffirmed this viewpoint in May following a review of 29 public health studies on cancer rates among people exposed to low-dose radiation, including those affected by the U.S. World War II atomic bomb droppings in Japan, leak-prone Soviet nuclear installations, medical treatments, and other sources.

Findings from 20 of the studies fall in line with the principle that even low-dose exposures cause an increase in cancer rates, whereas most of the other studies were found to be inconclusive and one was deemed flawed.

Roy Shore, chief of research at the Radiation Effects Research Foundation, a joint project of the United States and Japan, and the chair of the review, said in an interview that those that claim a safe threshold does exist “would have to come up with some data. Certainly the evidence did not point that way,” reported the Associated Press.

Current EPA guidelines state that even exposures below 100 millisieverts – roughly equivalent to 25 chest X-rays or about 14 CT chest scans – slightly increases an individual's chances of developing cancer in the future, though a section was added in July emphasizing that the chance of incurring cancer from this was low.
“According to radiation safety experts, radiation exposures of ... 100 millisieverts usually result in no harmful health effects, because radiation below these levels is a minor contributor to our overall cancer risk,” says revised policy.

At the same time, the FDA broadly claims that a single CT scan with a dose of 100 millisieverts could potentially increase the risk of developing a fatal form of cancer in about 1 chance out of 2,000.

EPA spokesman John Konkus weighed in last Tuesday on the rule change, saying that proposal is focused on “increasing transparency on assumptions” around how the body reacts to different doses of dangerous substances, and that the agency “acknowledges uncertainty regarding health effects at low doses” and supports more research on that.

“The proposed regulation doesn’t talk about radiation or any particular chemicals. And as we indicated in our response, EPA’s policy is to continue to use the linear-no-threshold model for population-level radiation protection purposes, which would not, under the proposed regulation that has not been finalized, trigger any change in that policy,” he said, according to AP.

Morrison urges providers to continue abiding by standard guidelines on radiation exposure, and to utilize resources at their disposal to further expand their knowledge on the subject for various procedures.

“The Image Wisely campaign was created with the objective of lowering the amount of radiation used in medically necessary imaging studies and eliminating unnecessary procedures," he said. "Image Gently raises awareness of the opportunities to lower radiation dose in the imaging of children. We would also recommend X-RAY Risk.com for its comprehensive approach to patient and provider education. Additionally, the Health Physics Society offers excellent resources on radiation safety and protection.”

ASRT is currently reviewing the proposal to determine its impact on the ability of radiological technologists to provide safe and accurate care to patients and to protect themselves from unnecessary medical radiation exposure. Should that be the case, it plans to urge the EPA and congressional leaders to oppose the measure.

Calabrese did not respond for comment.