Science-informed Policy Making for Protecting People and the Environment from Radiation.

ABSTRACT: The process to arrive at the radiation protection practices of today to protect workers, patients, and the public, including sensitive populations, has been a long and deliberative one. This paper presents an overview of the US Environmental Protection Agency's (US EPA) responsibility in protecting human health and the environment from unnecessary exposure to radiation. The origins of this responsibility can be traced back to early efforts, a century ago, to protect workers from x rays and radium. The system of radiation protection we employ today is robust and informed by the latest scientific consensus. It has helped reduce or eliminate unnecessary exposures to workers, patients, and the public while enabling the safe and beneficial uses of radiation and radioactive material in diverse areas such as energy, medicine, research, and space exploration. Periodic reviews and analyses of research on health effects of radiation by scientific bodies such as the National Academy of Sciences, National Council on Radiation Protection and Measurements, United Nations Scientific Committee on the Effects of Atomic Radiation, and the International Commission on Radiological Protection continue to inform radiation protection practices while new scientific information is gathered. As a public health agency, US EPA is keenly interested in research findings that can better elucidate the effects of exposure to low doses and low dose rates of radiation as applicable to protection of diverse populations from various sources of exposure. Professional organizations such as the Health Physics Society can provide radiation protection practitioners with continuing education programs on the state of the science and describe the key underpinnings of the system of radiological protection. Such efforts will help equip and prepare radiation protection professionals to more effectively communicate radiation health information with their stakeholders.

Proposed Priorities for Low-Dose Radiation Research and Their Relevance to the Practice of Radiology.

Because ionizing radiation is widely used in medical imaging and in military, industry, and commercial applications, programmatic management and advancement in knowledge is needed, especially related to the health effects of low-dose radiation. The U.S. Congress in partnership with the U.S. Department of Energy called on the National Academies of Sciences, Engineering, and Medicine (NASEM) to develop a long-term strategic and prioritized agenda for low-dose radiation research. Low doses were defined as dose amounts less than 100 mGy or low-dose rates less than 5 mGy per hour. The 2022 NASEM report was divided into sections detailing the low-dose radiation exposure and health effects, scientific basis for radiation protection, status of low-dose radiation research, a prioritized radiation research agenda, and essential components of a low-dose radiation research program, including resources needed and recommendations for financial recourse. The purpose of this review is to summarize this report and examine the recommendations to assess how these pertain to the practice of radiology and medicine.

Measurable radiation levels around individuals externally contaminated by nuclear fallout‡.

During the early response to large-scale radioactive contamination events, people who are potentially affected need to be screened for radioactive contamination and public health staff need to triage individuals who may need immediate decontamination. This is typically done by screening individuals for external contamination using ionising radiation detection equipment. In this study, spatially and temporally dependent isotopic compositions from a simulated nuclear detonation and Monte Carlo methods were used to relate contamination activity levels to the measurable radiation levels at select distances away from an individual with whole-body contamination. Radionuclide-specific air kerma rate coefficients and Geiger-Mueller instrument response coefficients at five select distances from contaminated individuals are presented for 662 radionuclides. Temporally and spatially dependent incident-specific coefficients are presented for a hypothetical surface detonation of a 235U-fueled device.

Time Motion Studies for Conduct of Population Monitoring During Functional Radiological Exercises at Community Reception Centers.

OBJECTIVE: The objectives of this study were to: validate current capacity estimates for radiological emergency response by collecting time motion observations from stations that would be used for screening and decontaminating populations, and use collected times to evaluate potential impact on current throughput calculations. METHODS: Time observations were collected at 11 functional radiation exercises across the country and aggregated for analysis for population monitoring activities, including contamination screening, decontamination, and registration. Collected times were compared to published estimates in current planning guidance, and evaluated to determine the suitability of using exercise observations to estimate throughput capacity. RESULTS: 2532-time observations were collected from 11 functional exercises. Of those, 2380 were validated and used for analysis. Contamination screening times varied greatly from current guidance, ranging from 19% below to 267% above existing estimates. Measurements indicate that capacity to perform contamination screening is significantly overestimated when using current estimates of service times and calculations when compared to observed aggregate service times. CONCLUSION: Aggregate service time data presented in this study can be used to yield a more realistic estimate of capacity to respond to a radiation event.

A million persons, a million dreams: a vision for a national center of radiation epidemiology and biology.

BACKGROUND: Epidemiologic studies of radiation-exposed populations form the basis for human safety standards. They also help shape public health policy and evidence-based health practices by identifying and quantifying health risks of exposure in defined populations. For more than a century, epidemiologists have studied the consequences of radiation exposures, yet the health effects of low levels delivered at a low-dose rate remain equivocal. MATERIALS AND METHODS: The Million Person Study (MPS) of U.S. Radiation Workers and Veterans was designed to examine health effects following chronic exposures in contrast with brief exposures as experienced by the Japanese atomic bomb survivors. Radiation associations for rare cancers, intakes of radionuclides, and differences between men and women are being evaluated, as well as noncancers such as cardiovascular disease and conditions such as dementia and cognitive function. The first international symposium, held November 6, 2020, provided a broad overview of the MPS. Representatives from four U.S. government agencies addressed the importance of this research for their respective missions: U.S. Department of Energy (DOE), the Centers for Disease Control and Prevention (CDC), the U.S. Department of Defense (DOD), and the National Aeronautics and Space Administration (NASA). The major components of the MPS were discussed and recent findings summarized. The importance of radiation dosimetry, an essential feature of each MPS investigation, was emphasized. RESULTS: The seven components of the MPS are DOE workers, nuclear weapons test participants, nuclear power plant workers, industrial radiographers, medical radiation workers, nuclear submariners, other U.S. Navy personnel, and radium dial painters. The MPS cohorts include tens of thousands of workers with elevated intakes of alpha particle emitters for which organ-specific doses are determined. Findings to date for chronic radiation exposure suggest that leukemia risk is lower than after acute exposure; lung cancer risk is much lower and there is little difference in risks between men and women; an increase in ischemic heart disease is yet to be seen; esophageal cancer is frequently elevated but not myelodysplastic syndrome; and Parkinson's disease may be associated with radiation exposure. CONCLUSIONS: The MPS has provided provocative insights into the possible range of health effects following low-level chronic radiation exposure. When the 34 MPS cohorts are completed and combined, a powerful evaluation of radiation-effects will be possible. This final article in the MPS special issue summarizes the findings to date and the possibilities for the future. A National Center for Radiation Epidemiology and Biology is envisioned.

The role of radiation protection professionals in the landscape of low dose radiation.

Radiation protection professionals benefit from using and applying a robust system of radiological protection that has evolved and matured through decades of research and experience. Nevertheless, uncertainties in potential health effects from low doses and low dose rates of radiation continue to remain. This uncertainty, coupled with complex jargon and nuances, has created an environment where the system of radiological protection can be misrepresented, even by radiation safety professionals, and by extension, misunderstood by the public. While it is universally agreed that the linear-no-threshold model cannot adequately explain or predict health effects of low dose radiation for all cancers, all individuals, or all exposure situations, the recommendation of authoritative scientific bodies to use this model for managing risks of radiation exposure is unequivocal. The role of individual radiation protection professionals in communicating radiation health and risk information is critical and consistent with the primary objective of professional organisations that represent them, mainly to promote best science and practice of radiation protection. If radiation protection professionals provide advice contrary to the recommendations and advice of regulatory and authoritative scientific bodies, it can erode public confidence in the system of radiological protection and harm the credibility of our profession.

Monitoring and Dose Assessment for Children Following a Radiation Emergency-Part II: Calibration Factors for Thyroid Monitoring.

Past radiological and nuclear accidents have demonstrated that monitoring a large number of children following a radiological and nuclear emergency can be challenging, in accommodating their needs as well as adapting monitoring protocols and applying age-specific biokinetics to account for various ages and body sizes. This paper presents the derived calibration factors for thyroid monitoring of children of all ages recommended by the International Commission on Radiological Protection using four selected detectors at given times following a short-term (acute) intake of I by inhalation. These calibration factors were derived by Monte Carlo simulations using the models of various detectors and pediatric voxel phantoms. A collection of lookup tables is presented in this paper which may be directly used as a quick reference by emergency response personnel or technical experts performing thyroid monitoring and assessment without doing time-consuming calculations.

Radiation Exposure of Workers and Volunteers in Shelters and Community Reception Centers in the Aftermath of a Nuclear Detonation.

After a nuclear detonation, workers and volunteers providing first aid, decontamination, and population monitoring in public shelters and community reception centers will potentially be exposed to radiation from people they are assisting who may be contaminated with radioactive fallout. A state-of-the-art computer-aided design program and radiation transport modeling software were used to estimate external radiation dose to workers in three different exposure scenarios: performing radiation surveys/decontamination, first aid, and triage duties. Calculated dose rates were highest for workers performing radiation surveys due to the relative proximity to the contaminated individual. Estimated cumulative doses were nontrivial but below the occupational dose limit established for normal operations by the Occupational Safety and Health Administration.

Assessment of National Efforts in Emergency Preparedness for Nuclear Terrorism: Is there a Need for Realignment to Close Remaining Gaps?

This summary of the 53rd Annual Meeting of the National Council on Radiation Protection and Measurements (NCRP) captures the highlights of the presentations including the Warren K. Sinclair Keynote Address and the five scientific sessions and wrap-up summary and panel discussion of "Assessment of National Efforts in Emergency Preparedness for Nuclear Terrorism: Is There a Need for Realignment to Close Remaining Gaps?" The issue of radiological emergency preparedness has evolved in the last 20 y from a primarily nuclear power plant focus to a wider, more comprehensive approach that includes response to all types of radiological and nuclear emergencies, including terrorism. The meeting took an introspective look at the advances in radiological emergency preparedness in the last 15 y and focused on four major topic areas: plans and guidance, training and exercising for both the first responder and the first receiver communities, recovery and return, and communication. In each area, the speakers reflected on the current state of that specific area and provided three to five practicable priority actions/initiatives for future work. As a result of the meeting, NCRP has made a commitment to create a committee to write a commentary that will go into more detail in each of the proposed priority areas discussed in the meeting and provide a roadmap for future work.

NCRP Program Area Committee 3: Nuclear and Radiological Security and Safety.

The National Council on Radiation Protection and Measurements (NCRP) Program Area Committee (PAC) 3 covers the broad subject of nuclear and radiological security and safety and provides guidance and recommendations for response to nuclear and radiological incidents of both an accidental and deliberate nature. In 2017, PAC 3 Scientific Committee 3-1 completed the development of Guidance for Emergency Responder Dosimetry and began development of a companion commentary on operational aspects of that guidance. PAC 3 members also organized the technical program for the 2017 Annual Meeting of NCRP on "Assessment of National Efforts in Emergency Preparedness for Nuclear Terrorism: Is There a Need for Realignment to Close Remaining Gaps." Based on discussions and presentations at the annual meeting, PAC 3 is working to develop a commentary on the subject that could serve as a roadmap for focusing our national efforts on the most pressing needs for preparing the nation for nuclear and radiological emergencies. PAC 3 is also engaged in active discussions exploring the landscape of priority issues for its future activities. An important consideration in this discussion is the extent of NCRP's present and potential future resources to support the work of its scientific committees.

US CENTERS FOR DISEASE CONTROL AND PREVENTION EXPERIENCE IN THE JOINT EXTERNAL EVALUATION PROCESS-RADIATION EMERGENCIES TECHNICAL AREA.

In 2015-16, the US Department of Health and Human Services led 23 US Government (USG) agencies including the Centers for Disease Control and Prevention (CDC), and more than 120 subject matter experts in conducting an in-depth review of the US core public health capacities and evaluation of the country's compliance with the International Health Regulations using the Joint External Evaluation (JEE) methodology. This two-part process began with a detailed 'self-assessment' followed by a comprehensive independent, external evaluation conducted by 15 foreign assessors. In the Radiation Emergencies Technical Area, on a scale from 1-lowest to 5-highest, the assessors concurred with the USG self-assessed score of 3 in both of the relevant indicators. The report identified five priority actions recommended to improve the USG capacity to handle large-scale radiation emergencies. CDC is working to implement a post-JEE roadmap to address these priority actions in partnership with national and international partners.

Proposed "Exposure And Symptom Triage" (EAST) Tool to Assess Radiation Exposure After a Nuclear Detonation.

ABSTRACTOne of the biggest medical challenges after the detonation of a nuclear device will be implementing a strategy to assess the severity of radiation exposure among survivors and to triage them appropriately. Those found to be at significant risk for radiation injury can be prioritized to receive potentially lifesaving myeloid cytokines and to be evacuated to other communities with intact health care infrastructure prior to the onset of severe complications of bone marrow suppression. Currently, the most efficient and accessible triage method is the use of sequential complete blood counts to assess lymphocyte depletion kinetics that correlate with estimated whole-body dose radiation exposure. However, even this simple test will likely not be available initially on the scale required to assess the at-risk population. Additional variables such as geographic location of exposure, sheltering, and signs and symptoms may be useful for initial sorting. An interdisciplinary working group composed of federal, state, and local public health experts proposes an Exposure And Symptom Triage (EAST) tool combining estimates of exposure from maps with clinical assessments and single lymphocyte counts if available. The proposed tool may help sort survivors efficiently at assembly centers near the damage and fallout zones and enable rapid prioritization for appropriate treatment and transport. (Disaster Med Public Health Preparedness. 2018; 12: 386-395).

Use of Transportable Radiation Detection Instruments to Assess Internal Contamination from Intakes of Radionuclides Part II: Calibration Factors and ICAT Computer Program.

The detonation of a radiological dispersion device or other radiological incidents could result in widespread releases of radioactive materials and intakes of radionuclides by affected individuals. Transportable radiation monitoring instruments could be used to measure radiation from gamma-emitting radionuclides in the body for triaging individuals and assigning priorities to their bioassay samples for in vitro assessments. The present study derived sets of calibration factors for four instruments: the Ludlum Model 44-2 gamma scintillator, a survey meter containing a 2.54 × 2.54-cm NaI(Tl) crystal; the Captus 3000 thyroid uptake probe, which contains a 5.08 × 5.08-cm NaI(Tl) crystal; the Transportable Portal Monitor Model TPM-903B, which contains two 3.81 × 7.62 × 182.9-cm polyvinyltoluene plastic scintillators; and a generic instrument, such as an ionization chamber, that measures exposure rates. The calibration factors enable these instruments to be used for assessing inhaled or ingested intakes of any of four radionuclides: Co, I, Cs, and Ir. The derivations used biokinetic models embodied in the DCAL computer software system developed by the Oak Ridge National Laboratory and Monte Carlo simulations using the MCNPX radiation transport code. The three physical instruments were represented by MCNP models that were developed previously. The affected individuals comprised children of five ages who were represented by the revised Oak Ridge National Laboratory pediatric phantoms, and adult men and adult women represented by the Adult Reference Computational Phantoms described in Publication 110 of the International Commission on Radiological Protection. These calibration factors can be used to calculate intakes; the intakes can be converted to committed doses by the use of tabulated dose coefficients. These calibration factors also constitute input data to the ICAT computer program, an interactive Microsoft Windows-based software package that estimates intakes of radionuclides and cumulative and committed effective doses, based on measurements made with these instruments. This program constitutes a convenient tool for assessing intakes and doses without consulting tabulated calibration factors and dose coefficients.

Managing Internal Radiation Contamination Following an Emergency: Identification of Gaps and Priorities.

Following a radiological or nuclear emergency, first responders and the public may become internally contaminated with radioactive materials, as demonstrated during the Goiânia, Chernobyl and Fukushima accidents. Timely monitoring of the affected populations for potential internal contamination, assessment of radiation dose and the provision of necessary medical treatment are required to minimize the health risks from the contamination. This paper summarizes the guidelines and tools that have been developed, and identifies the gaps and priorities for future projects.

Use of Transportable Radiation Detection Instruments to Assess Internal Contamination From Intakes of Radionuclides Part I: Field Tests and Monte Carlo Simulations.

The detonation of a radiological dispersion device or other radiological incidents could result in the dispersion of radioactive materials and intakes of radionuclides by affected individuals. Transportable radiation monitoring instruments could be used to measure photon radiation from radionuclides in the body for triaging individuals and assigning priorities to their bioassay samples for further assessments. Computer simulations and experimental measurements are required for these instruments to be used for assessing intakes of radionuclides. Count rates from calibrated sources of Co, Cs, and Am were measured on three instruments: a survey meter containing a 2.54 × 2.54-cm NaI(Tl) crystal, a thyroid probe using a 5.08 × 5.08-cm NaI(Tl) crystal, and a portal monitor incorporating two 3.81 × 7.62 × 182.9-cm polyvinyltoluene plastic scintillators. Computer models of the instruments and of the calibration sources were constructed, using engineering drawings and other data provided by the manufacturers. Count rates on the instruments were simulated using the Monte Carlo radiation transport code MCNPX. The computer simulations were within 16% of the measured count rates for all 20 measurements without using empirical radionuclide-dependent scaling factors, as reported by others. The weighted root-mean-square deviations (differences between measured and simulated count rates, added in quadrature and weighted by the variance of the difference) were 10.9% for the survey meter, 4.2% for the thyroid probe, and 0.9% for the portal monitor. These results validate earlier MCNPX models of these instruments that were used to develop calibration factors that enable these instruments to be used for assessing intakes and committed doses from several gamma-emitting radionuclides.

US screening of international travelers for radioactive contamination after the Japanese nuclear plant disaster in March 2011.

On March 11, 2011, a magnitude 9.0 earthquake and subsequent tsunami damaged nuclear reactors at the Fukushima Daiichi complex in Japan, resulting in radionuclide release. In response, US officials augmented existing radiological screening at its ports of entry (POEs) to detect and decontaminate travelers contaminated with radioactive materials. During March 12 to 16, radiation screening protocols detected 3 travelers from Japan with external radioactive material contamination at 2 air POEs. Beginning March 23, federal officials collaborated with state and local public health and radiation control authorities to enhance screening and decontamination protocols at POEs. Approximately 543 000 (99%) travelers arriving directly from Japan at 25 US airports were screened for radiation contamination from March 17 to April 30, and no traveler was detected with contamination sufficient to require a large-scale public health response. The response highlighted synergistic collaboration across government levels and leveraged screening methods already in place at POEs, leading to rapid protocol implementation. Policy development, planning, training, and exercising response protocols and the establishment of federal authority to compel decontamination of travelers are needed for future radiological responses. Comparison of resource-intensive screening costs with the public health yield should guide policy decisions, given the historically low frequency of contaminated travelers arriving during radiological disasters.

Murder by radiation poisoning: implications for public health.

On November 23, 2006, former Russian military intelligence officer Alexander Litvinenko died in a London hospital. Authorities determined he was deliberately poisoned with the radionuclide Polonium-210 (210Po). Police subsequently discovered that those involved in this crime had--apparently inadvertently--spread 210Po over many locations in London. The United Kingdom Health Protection Agency (HPA) contacted many persons who might have been exposed to 210Po and provided voluntary urine testing. Some of those identified as potentially exposed were U.S. citizens, whom the HPA requested that the Centers for Disease Control and Prevention (CDC) assist in contacting. CDC also provided health care professionals and state and local public health officials with guidance as to how they might respond should a Litvinenko-like incident occur in the U.S. This guidance has resulted in the identification of a number of lessons that can be useful to public health and medical authorities in planning for radiological incidents. Eight such lessons are discussed in this article.