During a nuclear/radiological incident or an accident involving internal intakes with radioactive cobalt or strontium, the recommended treatments, consisting of the administration of diethylenetriaminepentaacetic acid for 60 Co and calcium gluconate for 90 Sr, are of low specificity, and their effectiveness can be enhanced. In this manuscript, a liposomal formulation was developed to deliver potential chelating agents to the main retention organs of both radionuclides. A bisphosphonate, etidronate, has been selected as a possible candidate due to its satisfying decorporation activity for uranium, bone tropism, and potential affinity with cobalt. Pre-clinical studies have been carried out on rats using radionuclide contamination and treatment administration by the intravenous route. The effectiveness of free or liposomal etidronate was evaluated, with an administration at 30 min, 48 h post-contamination with 60 Co. Regarding 85 Sr, a more extended experiment with etidronate liposomes was performed over 6 d. The results were compared to those performed with reference treatments, diethylenetriaminepentaacetic acid for cobalt and calcium gluconate for strontium. Unexpected results were found for the reference treatments that were significantly less effective than previously reported or showed no effectiveness. Free etidronate revealed no significant efficacy after 48 h, but the liposomal form suggested an interaction with radionuclides, not sufficient to change the biokinetics. This study emphasizes the need for early treatment administration and further research to provide a more effective medical countermeasure.

Radiation protection contains the key elements of nuclear safety and security. Despite the overlap between nuclear safety and security, their objectives differ fundamentally, focusing on unintentional accidents and intentional malicious events, respectively. As such, the Potential Facility Risk Index (PFRI), originally created for security purposes, has evolved into an approach that combines conventional probabilistic risk assessment (PRA), which is a widely employed method to evaluate the safety risks of nuclear facilities. This research has developed a risk assessment model within the PFRI framework to calculate the probability of nuclear terrorism. Three essential components of the model are integrated: an analysis of historical nuclear terrorism data to determine an initial threat frequency; the target-specific factor using analytical hierarchy process (AHP) target attractiveness analysis; and the adversary motivation factor based on site-specific social influences from the Profiles of Individual Radicalization in the United States (PIRUS) dataset. Applied to a hypothetical nuclear facility, the model produces a nuclear terrorism probability of 8.97 × 10 -3 y - 1 . The systematic methodology proposed in the study enables the derivation of nuclear terrorism probability with results in the same risk unit as safety risk assessment. This method allows decision makers to seamlessly incorporate nuclear safety and security risk assessments, offering a comprehensive perspective. Consequently, it enriches comprehension of nuclear facility risks and establishes the groundwork for future advancements.

This research examines the cognitive frameworks used by HAZMAT technicians when responding to incidents involving Radiological Dispersal Devices (RDDs), which are conventional explosive devices with radioactive materials incorporated. The objective is to introduce the Expected Mental Model State (EMMS) as a comprehensive evaluation tool for assessing and enhancing the expertise and situational awareness of emergency responders dealing with radiation crises. Through a series of expert focus group sessions using the well-established qualitative methodology of grounded theory, an Expected Mental Model State (EMMS) was developed. The methodology used an influence diagram architecture to conceptually capture and codify key areas relevant to effective emergency response. The research identifies fourteen EMMS key conceptual domains, further elaborated into 301 subtopics, providing a multi-dimensional structure for the proposed mental model framework. Three pivotal notions of mental model emerged within the EMMS framework: Knowledge Topology, Envisioning (Belief), and Response and Operability. These notions were found to align with previous theories of mental models and are vital for understanding how HAZMAT technicians conceptualize and respond to RDD incidents. The study emphasizes the critical role of mental models in enhancing preparedness and effective response strategies during radiation emergencies. The EMMS framework offers a versatile methodology that can be adapted across various kinds of emergency responders and high-risk situations, including the broader Chemical, Biological, Radiological, and Nuclear (CBRN) spectrum. Using this EMMS framework to develop an EMMS Diagnostic Matrix can provide a roadmap for identifying areas for the development of specialized training modules that have the potential to significantly elevate both the quality and efficacy of responder training and preparation.

The performance of a LaBr3(Ce) gamma spectrometer at high count rates was investigated up to an input count rate of 1.3 Mcps. In order to make its pulse processing faster, a preamplifier provided by the detector manufacturer was eliminated, and the signal from the photomultiplier tube was fed directly to a digital pulse processing system. To accomplish both fast pulse processing and good energy resolution, the pulse-shaping parameters were optimized at a low count rate of 1.5 kcps, and then measurements were carried out at various count rates. Input count rates ranging from 1.5 kcps to 21 kcps were produced using a set of 137Cs resin sources, while higher rates between 45 kcps and 1.3 Mcps were produced using a 1.2-GBq 137Cs source. The spectrometer showed an excellent performance for the input rate up to 150 kcps, while the dead time increased rapidly for the input rates above 150 kcps. The system dead time has been improved greatly by eliminating the preamplifier.

It is now well accepted that the mechanisms induced by low-dose exposures to ionizing radiation (LDR) are different from those occurring after high-dose exposures. However, the downstream effects of these mechanisms are unclear as are the quantitative relationships between exposure, effect, harm, and risk. In this paper, we will discuss the mechanisms known to be important with an overall emphasis on how so-called "non-targeted effects" (NTE) communicate and coordinate responses to LDR. Targeted deposition of ionizing radiation energy in cells causing DNA damage is still regarded as the dominant trigger leading to all downstream events whether targeted or non-targeted. We regard this as an over-simplification dating back to formal target theory. It ignores that last 100 y of biological research into stress responses and signaling mechanisms in organisms exposed to toxic substances, including ionizing radiation. We will provide evidence for situations where energy deposition in cellular targets alone cannot be plausible as a mechanism for LDR effects. An example is where the energy deposition takes place in an organism not receiving the radiation dose. We will also discuss how effects after LDR depend more on dose rate and radiation quality rather than actual dose, which appears rather irrelevant. Finally, we will use recent evidence from studies of cataract and melanoma induction to suggest that after LDR, post-translational effects, such as protein misfolding or defects in energy metabolism or mitochondrial function, may dominate the etiology and progression of the disease. A focus on such novel pathways may open the way to successful prophylaxis and development of new biomarkers for better risk assessment after low dose exposures.

This note deals with epidemiological data interpretation supporting the linear no-threshold model, as opposed to emerging evidence of adaptive response and hormesis from molecular biology in vitro and animal models. Particularly, the US-Japan Radiation Effects Research Foundation's lifespan study of atomic bomb survivors is scrutinized. We stress the years-long lag of the data processing after data gathering and evolving statistical models and methodologies across publications. The necessity of cautious interpretation of radiation epidemiology results is emphasized.

As one of the most influential radiation geneticists of the 20th century, Hermann J. Muller had a major role in the development and widespread acceptance of the linear no-threshold (LNT) dose response for hereditary and cancer risk assessments worldwide. However, a spate of historical reassessments have challenged the fundamental scientific foundations of the LNT model, drawing considerable attention to issues of ethical probity and the scientific leadership of Muller. This review paper raises further questions about the objectivity of Muller with respect to the LNT model. It is shown that Muller supported Ernest Sternglass's findings and interpretations concerning radiation-induced childhood leukemia, which have been widely and consistently discredited. These findings provide further evidence that Muller's actions with respect to radiation cancer risk assessment were far more ideologically than scientifically based.