Among the more worrisome proposals now wending its way through Washington, DC, is one that would weaken standards for ionizing radiation and increase exposures into the general environment from diagnostic procedures and laboratories and workplaces. Because there is no known safe level of exposure to ionizing radiation, and because there are documented increases in rates of leukemia or breast cancer in those receiving X-rays all around the world today, current standards for diagnostic radiation are set as low as reasonably achievable exposures (ALARA) especially for children.
The pending Environmental Protection Agency proposal to increase releases of ionizing radiation is based on the fact that there are indeed some specific circumstances–in adults– where low doses of radiation or exposure to a toxic chemical can be beneficial. In fact, there is no debate that radiation can be beneficial for those with pre-existing chronic conditions. When my dad was crippled by cancer riddled through his bones, radiation relieved his pain tremendously. For patients like my father with metastatic tumors, treatment works precisely because radiation kills cancer cells that are the cause of their pain–at least for a while. The example of pain reduction for arthritis is also well-known and is the foundation for radiation spas around Europe. In these instances a trade-off is made between the immediate benefit of pain relief in contrast to the longer term risk of higher cancer rates.
The fact that this benefit in lessening pain is clear should not in any way suggest that broader benefits may be at hand from allowing higher doses of radiation to become widespread, nor does it indicate that children could safely be subject to greater exposures than now permitted. It is a well-established principle of toxicology that dose makes the poison, but equally important is the consideration that timing of exposure is of critical importance. Thus, because the brains of children more than double in the first two years of life, they are exquisitely sensitive to the mind-numbing exposures to lead or other heavy metals. Similarly, the American College of Pediatric Radiology has for years advised special caution in using diagnostic radiation with young children recognizing their greater vulnerability to the damaging impact of such exposures on their capacity to learn as well as increasing their cancer risk.
Think of this. After the bombs fell on Hiroshima at the end of World War Two, a major surveillance program followed. Within a decade the risk of leukemia became evident in those that had relatively high exposures. Those who were youngest when first exposed developed the highest relative risk of the disease. Now some 70 years later data clearly show that even those with much lower estimated doses of radiation nonetheless incurred major risks to their health, including elevated rates of heart disease and cancer. In fact, what can appear to be short-term benefits such as stimulating cell growth or treating orthopedic abnormalities, ultimately in the long-turn proved to result in greater health burdens. While there are major differences between and among individuals in responding to a single specific toxic agent, the real world is an inherently complex mixture. Thus, the same targeted radiation that relieved my dad’s pain, also increased the chances that the cancer of his bone marrow could surge as it did
Some have argued that because these benefits of radiation in reducing pain take place, we should upend years of policy-making and view low-doses as generally beneficial rather than harmful. This would profoundly change the modern approach to chemical and radiation control that rests on a substantial foundation of both experimental and human research carried out in different organisms with different materials.
As a matter of policy, the World Health Organization, the State of California, and the U.S. flagship testing program, the National Toxicology Program, all treat any finding of cancer in animals under a controlled study design as an indication that the same compound can produce cancer at lower doses in the human population. The foundation for this view is simple—every agent that we know can cause cancer in humans, also produces it in animals when adequately tested.
What then to make of the argument to increase radiation exposures throughout our population? This contention rests on numerous review articles by toxicologist Edward Calabrese and colleagues arguing that
“If low-dose stimulatory responses [hormesis] were assumed to be beneficial, the decision maker could view hormesis as adding potential benefit to society and could estimate an optimized population-based exposure standard.”
Rejecting this proposal, my colleagues and I have written a peer-reviewed publication where we contend that instances of the benefit of low doses of radiation such as those that aided my dad, are unique and cannot be broadly generalized, particularly with respect to the young or the elderly. The upside of weakening radiation regulations is straightforward: nuclear accidents will not need to be cleaned up to the same extent, and releases of radiation from coal-burning–a major source of environmental radiation–can also be relaxed. Indeed, it is far easier to count deaths resulting from mass evacuations as happened following the Fukushima meltdown in Japan, than it is to determine the number of additional deaths from cancer that will take place over the next four decades as a result. Of course, weakening standards for radiation translates into reduced operating costs for the coal and nuclear industry. But, what does this portend for the rest of us?
One must ask what is the downside risk to our society of changing the fundamental assumption about agents that can cause cancer? Even with current relatively stringent standards for diagnostic radiation, there have been so many instances of over-exposure to radiation from CT scans resulting in burned skin, damaged organs and increased cancer risk that this area has become a specialty for malpractice attorneys. Indeed, in this century more radiation occurs from medical devices than from background sources. A single full-body CT scan results in the same amount of radiation shown to increase cancer in the Hiroshima survivors, according to David J. Brenner and Carl D. Elliston writing in the journal Radiology. They write that repeated scans are believed to be responsible for a growing portion of cancer in children and young adults.
What then to make of pending EPA proposals that would allow greater radiation not only to nuclear power plant and other workers but to patients, including the young, the elderly and those with chronic illnesses? In fact, patterns of workplace cancer have been declining in the past few decades for two different reasons. First of all the proportion of American workers exposed to toxic chemicals and ionizing radiation is at the lowest level in modern history resulting in relatively lower exposures to much of the workforce. In addition, modernization and automation, along with general awareness of the need to reduce toxic exposures and some effort at regulatory control, have also lowered some individual risks. But while worker risks may have declined, those to the general population have risen dramatically, because the use of diagnostic radiation from CT scans and nuclear medicine tests ( as stress EKG’s) rose more than 7-fold from 1980 to 2006, according to the National Council on Radiation Protection, Report No. 160.
As one indication of the complexity of the matter, consider that radiation can be both a cause of the benign tumor of the meninges(meningioma) and can also be used to treat the disease when it occurs in certain areas of the brain. Sometimes radiation is applied both through an external beam into the tumor from several angles and also by being sent to specific areas glommed onto bone-seeking chemicals such as strontium or radium. The inarguable fact that some applications of radiation can be beneficial in targeted circumstances does not rationalize a general increase in exposures to the healthy population.
No less an authority than the National Academies of Sciences has weighed in on this matter in the National Research Council report on health risks from exposure to low levels of ionizing radiation (BEIR VII, 2005): “The assumption that any stimulatory hormetic effects from low doses of ionizing radiation will have a significant health benefit to humans that exceeds potential detrimental effects from the radiation exposure is unwarranted.”
No matter how well it may play in some political arenas, bad science makes for bad policy.