Beyond dose assessment: using risk with full disclosure of uncertainty in public and scientific communication

Parameter Values for Estimation of Internal Doses from Ingestion of Radioactive Fallout from Nuclear Detonations

ABSTRACT

This paper suggests values or probability distributions for a variety of parameters used in estimating internal doses from radioactive fallout due to ingestion of food. Parameters include those needed to assess the interception and initial retention of radionuclides by vegetation, translocation of deposited radionuclides to edible plant parts, root uptake by plants, transfer of radionuclides from vegetation into milk and meat, transfer of radionuclides into non-agricultural plants and wildlife, and transfer from food and drinking water to mother's milk (human breast milk). The paper includes discussions of the weathering half-life for contamination on plant surfaces, biological half-lives of organisms, food processing (culinary factors), and contamination of drinking water. As appropriate, and as information exists, parameter values or distributions are specific for elements, chemical forms, plant types, or other relevant characteristics. Information has been obtained from the open literature and from publications of the International Atomic Energy Agency. These values and probability distributions are intended to be generic; they should be reviewed for applicability to a given location, time period, or season of the year, as appropriate. In particular, agricultural practices and dietary habits may vary considerably both with geography and over time in a given location.

Fallout from Nuclear Weapons Tests: Environmental, Health, Political, and Sociological Considerations

The process of nuclear fission, which was discovered in 1938, opened the door to the production of nuclear weapons, which were used in 1945 by the United States against Japan in World War II, and to the detonation of >500 nuclear weapons tests in the atmosphere by the United States, the former Soviet Union, the United Kingdom, China, and France from 1946-1980. Hundreds of radionuclides, most of them short-lived, were produced in the atmospheric tests. The radioactive clouds produced by the explosions were usually partitioned between the troposphere and the stratosphere: the activity that remained in the troposphere resulted in local and regional fallout, consisting mainly of short-lived radionuclides and in relatively high doses for the populations residing in the vicinity of the test site, whereas the activity that reached the stratosphere returned to the ground with a half-life of ~1 y and was composed of long-lived radionuclides that contaminated all uncovered materials on Earth to a small extent and led to low-level irradiation of the world population for decades or more. The health effects resulting from exposure to radioactive fallout constitute, in most cases, small excesses over baseline rates for thyroid cancer and leukemia. An extra 49,000 cases of thyroid cancer would be expected to occur among the US population from exposure to radioactive fallout from the atmospheric nuclear weapons tests that were conducted at the Nevada Test Site in the 1950s. In addition, there could be as many as 11,000 deaths from non-thyroid cancers related to fallout from all atmospheric tests that were conducted at all sites in the world, with leukemia making up 10% of the total. Public concern arose in part from the secrecy that surrounded the nuclear testing programs and, for a long time, the poor communication regarding the consequences of the tests, both in terms of radiation doses and of health effects. Sociological and political pressures contributed to the establishment of programs of compensation for radiation exposures and evidence of radiation-induced diseases in countries that incurred significant fallout from nuclear weapons testing.

Cone-Beam Computed Tomography in Orthodontics

Unlike patients receiving implants or endodontic treatment, most orthodontic patients are children who are particularly sensitive to ionizing radiation. Cone-beam computed tomography (CBCT) carries risks and benefits in orthodontics. The principal risks and limitations include ionizing radiation, the presence of artifacts, higher cost, limited accessibility, and the need for additional training. However, this imaging modality has several recognized indications in orthodontics, such as the assessment of impacted and ectopic teeth, assessment of pharyngeal airway, assessment of mini-implant sites, evaluation of craniofacial abnormalities, evaluation of sinus anatomy or pathology, evaluation of root resorption, evaluation of the cortical bone plate, and orthognathic surgery planning and evaluation. CBCT is particularly justified when it brings a benefit to the patient or changes the outcome of the treatment when compared with conventional imaging techniques. Therefore, CBCT should be considered for clinical orthodontics for selected patients. Prescription of CBCT requires judicious and sound clinical judgment. The central question of this narrative review article is: when does CBCT add value to the practice of orthodontics? To answer this question, this article presents discussion on radiation dosage of CBCT and other imaging techniques used in orthodontics, limitations of CBCT in orthodontics, justifying the use of CBCT in orthodontics, and the benefits and evidence-based indications of CBCT in orthodontics. This review summarizes the central themes and topics in the literature regarding CBCT in orthodontics and presents ten orthodontic cases in which CBCT proved to be valuable.

Saving Lives and Preventing Injuries From Unjustified Protective Actions-Method for Developing a Comprehensive Public Protective Action Strategy for a Severe NPP Emergency

During the response to the Fukushima Daiichi nuclear power plant (FDNPP) emergency, about 50 patients died during or shortly after an evacuation when they were not provided with the needed medical support. In addition, it has been shown that during the FDNPP emergency there were increases in mortality rates among the elderly due to long-term dislocation as a result of evacuation and relocation orders and an inability to stay in areas where residents were advised to shelter for extended periods. These deaths occurred even though the possible radiation exposure to the public was too low to result in radiation-induced deaths, injuries, or a meaningful increase in the cancer rate, even if no protective actions had been taken. These problems are not unique to the FDNPP emergency and would be expected if the recommendations of many organizations were followed. Neither the International Commission on Radiological Protection (ICRP), the U.S. Nuclear Regulatory Commission (NRC) nor the U.S Environmental Protection Agency (EPA) adequately take into consideration in their recommendations and analysis the non-radiological health impacts, such as deaths and injuries, that could result from protective actions. Furthermore, ICRP, NRC, EPA, and the U.S. Department of Homeland Security (DHS) call for taking protective actions at doses lower than those resulting in meaningful adverse radiation-induced health effects and do not state the doses at which such effects would be seen. Consequently, it would be impossible for decision makers and the public to balance all the hazards both from radiation exposure and protective actions when deciding whether a protective action is justified. What is needed, as is presented in this paper, is a method for developing a comprehensive protective action strategy that allows the public, decision makers, and others who must work together to balance the radiological with the non-radiological health hazards posed by protective actions, and to counter the exaggerated fear of radiation exposure that could lead to taking unjustified protective actions and adverse psychological, sociological, and other effects.

An overview of current knowledge concerning the health and environmental consequences of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident

Since 2011, the scientific community has worked to identify the exact transport and deposition patterns of radionuclides released from the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan. Nevertheless, there still remain many unknowns concerning the health and environmental impacts of these radionuclides. The present paper reviews the current understanding of the FDNPP accident with respect to interactions of the released radionuclides with the environment and impacts on human and non-human biota. Here, we scrutinize existing literature and combine and interpret observations and modeling assessments derived after Fukushima. Finally, we discuss the behavior and applications of radionuclides that might be used as tracers of environmental processes. This review focuses on (137)Cs and (131)I releases derived from Fukushima. Published estimates suggest total release amounts of 12-36.7PBq of (137)Cs and 150-160PBq of (131)I. Maximum estimated human mortality due to the Fukushima nuclear accident is 10,000 (due to all causes) and the maximum estimates for lifetime cancer mortality and morbidity are 1500 and 1800, respectively. Studies of plants and animals in the forests of Fukushima have recorded a range of physiological, developmental, morphological, and behavioral consequences of exposure to radioactivity. Some of the effects observed in the exposed populations include the following: hematological aberrations in Fukushima monkeys; genetic, developmental and morphological aberrations in a butterfly; declines in abundances of birds, butterflies and cicadas; aberrant growth forms in trees; and morphological abnormalities in aphids. These findings are discussed from the perspective of conservation biology.

Event-based versus process-based informed consent to address scientific evidence and uncertainties in ionising medical imaging

Background

Inappropriate ionising medical imaging has been escalating in the last decades. This trend leads to potential damage to health and has been associated to bioethical and legal issues of patient autonomy.

Methods

While the doctrine underlines the importance of using informed consent to improve patient autonomy and physician-patient communication, some researchers have argued that it often falls short of this aim. There are basically two different informed consent practices. The first — the so-called “event-based model” — regards informed consent as a passive signature of a standard unreadable template, performed only once in each medical pathway. The second — the so-called “process-based model” — integrates information into the continuing dialogue between physician and patient, vital for diagnosis and treatment.

Results

Current medical behaviour often embraces the event-based model, which is considered ineffective and contributes to inappropriateness. We sought, in this review, to analyse from juridical and communication standpoints whether process-based informed consent can deal with scientific uncertainties in radiological decision-making. The informed consent is still a distinctive process in defence of both patients’ and physicians’ health and dignity in rule-of-law states and consequently in curtailing the abuse of ionising medical radiation.

Main Messages

• Inappropriate ionising medical imaging is widespread and increasing worldwide.

• This trend leads to noteworthy damage to health and is linked to the issue of patient autonomy.

• Some authors have argued that informed consent often falls short of improving patient autonomy.

• Process-based informed consent can deal with scientific uncertainties to contrast inappropriateness.

• Informed consent is still a distinctive process in defence of both patients and physicians.