The idea cancer can be induced by low doses of ionizing radiation has been very controversial since the 1970s.
Scientific and regulatory bodies currently estimate the risk of low doses by extrapolating directly (linearly) from the risk known to exist from high doses. They assume there is no threshold of exposure to radiation below which cancer might not be caused and that a low dose of radiation might have a protective effect called hormesis.
This theory, the linear no-threshold model (LNT), has been used to establish radiation regulations for many decades, despite the fact hundreds of studies over the years have called the claim into question.
Discovery of the original studies, which many previously believed to be lost and upon which LNT was established, has overturned the flawed theory exposure to a single particle of radiation could lead to cancer. Early research indicating there is no minimum safe threshold for exposure to radiation led the U.S. National Academy of Sciences (NAS) to mistakenly adopt LNT for cancer risk assessment. The effects of that decision for subsequent health and safety regulation cannot be overstated.
Based on NAS’ recommendations, the U.S. Environmental Protection Agency (EPA), other regulatory agencies, and the medical community have worked under the assumption even small radiation doses should be avoided, no matter how great the cost, in almost all instances, because the risk of radiation exposure could lead to cancer.
Utilizing LNT as the guideline, the use of radiation in medicine has been unnecessarily restricted in instances in which broader use, sometimes as a preventative measure, could have improved health outcomes.
Employing LNT as a standard for regulation has also increased the cost of government regulations by billions of dollars. The safety margins built into nuclear power plants to prevent exposure to small doses of radiation, expensive safety protocols and technologies required for environmental clean-ups, and radon regulations based on LNT unnecessarily raise the cost of environmental clean-ups, spark unnecessary fears in homeowners, and in the case of nuclear plants, hamper construction by making their costs exorbitant.
Scientifically Unethical Claims
In a series of articles published in various peer-reviewed scientific journals, Calabrese shows the original studies that served as the basis for the LNT were seriously flawed.
For instance, the studies extrapolated from the health effects of radiation exposure to abnormal populations of fruit flies and mice to estimate the effects of radiation on human populations, which is scientifically unjustifiable and unethical.
Calabrese’s research reconstructs the history of LNT, the work of leaders of the radiation-genetics community of the 1940s through the 1960s, and how NAS, citing its own work, recommended the United States switch from a threshold model to a linear model for risk assessment in 1956. The previous threshold model found there were safe doses of exposure to radiation, meaning under that model, it was not expected persons exposed to low doses of radiation would develop cancer at unusual rates. The increased cancer risk emerges when thresholds of exposure at high doses of radiation are surpassed.
Ideological Biases, Deliberate Deception
Calabrese’s newest article focuses on risk assessment activities from the early 1970s to the present. His previous research showed the scientific researchers pushing LNT theory were guided by profound ideological biases that led to a series of documented deceptions, obfuscations, and scientific misconduct. The scientific and regulatory communities uncritically accepted this misinformation, and it continues to guide regulatory actions today.
A significant question facing society, elected officials, and regulatory agencies is how will they respond to the fact numerous regulations are based on the mistaken adoption of LNT as the standard for exposure to radiation. Calabrese’s research shows the emperor has no clothes. By adopting this standard, NAS and regulatory agencies have placed the American people in a compromised position, adversely affecting their health and economy and their trust in the scientific community.
Edward J. Calabrese, Ph.D. ([email protected]) is a professor in the Department of Environmental Health Sciences at the University of Massachusetts-Amherst. Jay Lehr, Ph.D. ([email protected]) is science director at The Heartland Institute.
Edward J. Calabrese, “Obituary Notice: LNT Dead at 89 years, a Life in the Spotlight,” Environmental Research, February 24, 2017: https://heartland.org/publications-resources/publications/obituary-notice-lnt-dead-at-89-years-a-life-in-the-spotlight