In 1895, Wilhelm Roengten “discovered” ionizing radiation. Only a few years later Madam Curie “discovered” and later isolated naturally occurring radioactive elements. Of course, neither of these pioneering scientists invented the property of radioactivity or ionizing radiation. Radioactivity and ionizing radiation have been with us since the creation of our planet, and indeed, since the creation of the universe. Radioactivity and ionizing radiation are as ubiquitous and common as those primordial “elements”–earth, fire, water, and air. However, human senses, while evolving in such a radioactive environment, do not include the ability to innately “sense” radioactivity or ionizing radiation. This lack of such a human ability seems to have imbued radioactivity and its associated ionizing radiation with mystic, almost magical or supernatural, properties, and all too often, a sinister or even deadly intent.
But initially, as is typically the case, new scientific discoveries led to the development of new technologies to use this “new” science. First, medical uses for radioactivity and ionizing radiation were developed, later expanding to industrial and commercial uses, and in time to energy and military applications. The potential uses of radioactivity and ionizing radiation seemed boundless, but there was just one small problem.
Very shortly after the discovery of radioactivity and ionizing radiation, the potential hazards associated with excessive exposure quickly became apparent. But how much exposure was excessive, and how could we use the new technologies while avoiding these hazards? New scientific bodies were established to try to answer these questions, such as the American Roentgen Ray Society, founded in 1900, and later the International Commission on Radiological Protection, which held its formative meeting in 1928. Numerous other national and international organizations have been formed to study and to try to provide guidance on use of radioactivity and ionizing radiation.
At first, these studies and subsequent radiation protection standards focused on protecting against acute radiation effects, such as skin erythema, and to determine how much exposure was tolerable without inducing acute effects. Indeed, some of the first protection standards were termed “tolerance doses.” However, as time progressed and the use of radioactivity and ionizing radiation grew, it became clear that there were other, more latent, potential hazards, such as cancer induction and possible hereditary effects associated with exposure. The focus of scientific study and radiation protection standards shifted to these more latent potential hazards. This chronology of the development of radiation protection standards has been extensively reviewed (Kathren 1962; Healy 1988; Jones 2005).
The development of atomic weaponry during the Manhattan Project began a new era in the perception of potential hazards associated with radioactivity and ionizing radiation. With the initial use of such weaponry and the continued development of atomic and nuclear weaponry by multiple countries, a new symbol emerged for such hazards and all things radioactive: the mushroom cloud. For many individuals, the Four Horsemen of the Apocalypse now had a fifth member: deadly radiation. Accidents involving the use of nuclear technology for energy generation—Three Mile Island in the United States (US) in 1979, Chernobyl in the former Soviet Union in 1986, and Fukushima Daiichi in Japan in 2011—only further heightened this anxiety and demonstrated that not only military applications were to be feared.
Throughout this backdrop of fear and anxiety, the unmistakable technological benefits of radioactivity and ionizing radiation persisted. But so did the questions of just what are the potential hazards and how to use this technology while avoiding, or perhaps minimizing, these potential hazards. In addition to the numerous national and international bodies attempting to address these questions, several gatherings of prominent scientists were held, notably the Wingspread Conference in 1998 and the Arlie Conference in 1999. Documents were issued by both conferences (CSSP 1998; Arlie 2000) describing the state of the then-current knowledge of potential hazards associated with radioactivity and ionizing radiation and providing recommendations on radiation protection standards. More recently, the Victor Bond Conference (HPS 2011) and the Health Physics Society (HPS 2016) have attempted to address these questions. However, it is debatable what impact any of these conferences, workshops, or documents have had on the actual state of radiation protection standards.
With this history in mind, in 2014, a small group of scientists and nuclear technologists1, led by Dr. Gary Troyer, began to ponder how to continue to take advantage of the many beneficial uses of radioactivity and ionizing radiation in the face of existing public perception and ever-increasingly restrictive radiation protection standards. With the untimely death of Dr. Troyer in 2014, Dr. Alan Waltar, Past-President of the American Nuclear Society (ANS), assumed leadership of this group, and so began the process that led to the joint ANS/HPS conference, “Applicability of Radiation-response Models to Low-dose Protection Standards.” The location selected for this conference was Pasco, WA, which is adjacent to the US Department of Energy Hanford Site. The Hanford Site was one of the principal sites for the Manhattan Project, was the US primary production site for weapons-grade plutonium, and was where Mr. Herbert M. Parker pioneered the application of radiation protection to a large-scale production site. It was thus an ideal location for such a conference.
Therefore, following years of discussions, debates, and effort, from 1–3 October 2018, more than 200 prominent scientists, regulators, nuclear technologists, and interested parties from around the world gathered in Pasco, WA, to once again address these most fundamental questions in radiation protection: (1) how much exposure is too much, and (2) how to avoid too much exposure AND still use the benefits of radioactivity and ionizing radiation.
It was important to have talks from those who are involved in the decisions related to regulatory standards. The first two plenary sessions allowed these speakers to inform the scientists and others at the meeting about their needs and the regulatory restrictions with which each agency must deal. This laid a useful framework for the meeting. As was the case for each session, this was followed up with a panel discussion to continue the subject and allow the audience to be involved in asking questions and providing additional information and viewpoints.
The next plenary session was designed to give the epidemiologists a chance to show the latest data on human populations exposed to radiation. Because epidemiology is the driving force in all regulations, having this session early in the meeting provided the basic groundwork on which the rest of the meeting could be constructed. The session focused on two important populations exposed during the development of the atomic bomb in Russia. The Mayak population consisted of workers exposed during the development of the bomb, and the Techa River population were residents exposed to the release of radioactive material into the environment. Both populations received doses that were higher than those received by most human populations. This dose was delivered at a low dose rate and was the result of both external and internally-deposited radioactive materials. This session resulted in a very good discussion during the panel where questions about the radiation dose and the biological effects were asked. The bottom line from these presentations was that there was an increase in the cancer frequency in these populations, and it was similar to that calculated for the Japanese atomic-bomb populations.
The poster session with more than 40 poster presentations was held that evening. The session was well attended and played an important part in the meeting.
After laying the groundwork by the regulators and the epidemiology studies, the next plenary session was focused on the basic biology to describe the response at the cell and molecular level to low doses and low-dose-rate radiation exposure. The take-home message from this session was basically that the biological response induced by low doses of radiation was very different from the response generated following exposure to high doses. This session thus concluded that the mechanisms of action are distinct as a function of dose and dose rate and provided much evidence for the potential for protective effects following low-dose and low-dose-rate exposures. This provided serious evidence that the linear no-threshold (LNT) model used in radiation protection is unsupported by basic science and represents an overestimate of the risk following exposure to low-dose and low-dose-rate radiation exposures. Again, the panel resulted in vigorous discussion with a wide range of different views.
With the previous sessions in place, it was then possible to discuss the models used to describe radiation dose-response relationships in the next plenary session. Much of this session was focused on the response in the low-dose region and what models were best supported by the scientific evidence in this region. This is where the three different groups discussed later found their voices: (1) the linear no-threshold group, (2) the threshold group, and finally, (3) the hormesis group. This discussion seemed to be one of the foci of much of the discussion in the meeting with little shift among those who seemed to support each of these positions.
In the next plenary session, the meeting shifted from basic science to the impact of radiation regulations with important presentations on the influence of fear, perception of risk, and costs associated with the current methods of regulating radiation. This impacted the field of medical use of radiation, use of radiation standards for nuclear cleanup, the value of human life, and the use of nuclear power to meet our nation’s energy needs. All of these areas impact our daily lives and require a well-thought-out approach to help us gain the benefit of radiation in each of these important fields.
Discussion of these areas led naturally to the next plenary session, which contained some very important presentations on the impact of fear, regulations, lack of communication, and public distrust of authority during the aftermath of the Fukushima accident. The presentations from those impacted by the accident brought a new sense of the importance of this meeting on future actions. What would you do if you were asked to leave your home after a nuclear accident? What level of radiation would make you abandon your home, your lifestyle, your ability to make your own decisions, and your family unity to avoid exposure to low doses of radiation delivered at a low dose rate? These questions provided a new look into each of our backgrounds and would have a wide range of responses depending on the background and fear for each individual. These questions were in part responsible for part of our follow-up with a survey to evaluate the feelings of those in attendance.
Finally, the conference asked the important question of what the needs are to move forward both in the area of the science as well as in communication, addressing fear, and helping understand the risk of radiation in the low-dose region. These needs are independent of the type of model used to describe the results in the low-dose region and the regulations used to limit the public exposure.
This conference included nine plenary sessions, seven panel discussions, Monday and Wednesday luncheon speakers, and a Tuesday night banquet speaker. The following proceedings provide abstracts for all presentations given during each of these sessions, panel discussions, and speakers. For all plenary sessions and panel discussions, the abstracts are followed by a discussion of the salient observations, discussions, and conclusions made during that session. In addition, appendices to these proceedings provide (1) a listing of all conference presenters and panelists, (2) a listing of all conference participants, and (3) a listing of all poster presentations.
Additional information from the conference beyond what is presented in these proceedings may be found on the conference website at http://lowdoserad.org/. This website includes copies of most of the conference presentations; biographies of many of the presenters; links to videos for all of the plenary sessions, panel discussions, and invited speakers; and other supplemental information.
This conference would not have been possible without the time, efforts, and devotion of numerous individuals and sponsors. Rather than repeat the names of these individuals and sponsors here, the reader is directed to the first section (Welcoming Session) of the following proceedings of this conference for a full listing.
The authors would also like to extend our special appreciation for those individuals involved in the production of these proceedings; in particular, our thanks to Steven Baker, Gerald Woodcock, Wanda Munn, and Ludwig Feinendegen for drafting and reviewing portions of the proceedings, and especially to Julie Wiley, who performed the technical editing for the entire proceedings.
Arlie International Conference. Final Report. Bridging radiation policy and science [online]. 2000. Available at https://hps.org/membersonly/documents/BRPSfinal.pdf
. Accessed 1 September 2019.
Council of Scientific Society Presidents. Wingspread Conference Final Report. Creating a strategy for science based national policy: addressing conflicting views on the health risks of low-level ionizing radiation [online]. 1998. Available at https://www.osti.gov/scitech/biblio/755413
. Accessed 1 September 2019.
Health Physics Society. Special issue: proceedings of the conference on biological consequences and health risks of low-level exposure to ionizing radiation in honor of Victor P. Bond. Health Phys 100:243–234; 2011.
Health Physics Society. Special issue: biological systems responses to low-dose radiation exposure—scientific and socioeconomic implications. Health Phys 110:241–304; 2016.
Healy JW. Radiation protection standards: a historical perspective. Health Phys 55:125–130; 1988.
Jones CG. A review of the history of US radiation protection regulations, recommendations, and standards. Health Phys 88:105–124; 2005.
Kathren RL. Early x-ray protection in the United States. Health Phys 8:503–511; 1962.
1Here “nuclear technologists” refers to anyone who is actively involved in the use or management of atomic or nuclear technology for beneficial purposes.