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A major source of data on metabolism, excretion and retention of plutonium comes from experimental animal studies. Although old world monkeys are one of the closest living relatives to humans, certain physiological differences do exist between these nonhuman primates and humans. The objective of this paper was to describe the metabolism of plutonium in nonhuman primates using the bioassay and retention data obtained from macaque monkeys injected with plutonium citrate. A biokinetic model for nonhuman primates was developed by adapting the basic model structure and adapting the transfer rates described for metabolism of plutonium in adult humans. Significant changes to the parameters were necessary to explain the shorter retention of plutonium in liver and skeleton of the nonhuman primates, differences in liver to bone partitioning ratio, and significantly higher excretion of plutonium in feces compared to that in humans.

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This study had a goal to evaluate the predictive capabilities of the National Council on Radiation Protection and Measurements (NCRP) wound model coupled to the International Commission on Radiological Protection (ICRP) systemic model for 90Sr-contaminated wounds using non-human primate data. Studies were conducted on 13 macaque (Macaca mulatta) monkeys, each receiving one-time intramuscular injections of 90Sr solution. Urine and feces samples were collected up to 28 d post-injection and analyzed for 90Sr activity. Integrated Modules for Bioassay Analysis (IMBA) software was configured with default NCRP and ICRP model transfer coefficients to calculate predicted 90Sr intake via the wound based on the radioactivity measured in bioassay samples. The default parameters of the combined models produced adequate fits of the bioassay data, but maximum likelihood predictions of intake were overestimated by a factor of 1.0 to 2.9 when bioassay data were used as predictors. Skeletal retention was also over-predicted, suggesting an underestimation of the excretion fraction. Bayesian statistics and Monte Carlo sampling were applied using IMBA to vary the default parameters, producing updated transfer coefficients for individual monkeys that improved model fit and predicted intake and skeletal retention. The geometric means of the optimized transfer rates for the 11 cases were computed, and these optimized sample population parameters were tested on two independent monkey cases and on the 11 monkeys from which the optimized parameters were derived. The optimized model parameters did not improve the model fit in most cases, and the predicted skeletal activity produced improvements in three of the 11 cases. The optimized parameters improved the predicted intake in all cases but still over-predicted the intake by an average of 50%. The results suggest that the modified transfer rates were not always an improvement over the default NCRP and ICRP model values.

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Authorship guidelines have established criteria to guide author selection based on significance of contribution and helped to define associated responsibilities and accountabilities for the published findings. However, low awareness, variable interpretation, and inconsistent application of these guidelines can lead to confusion and a lack of transparency when recognizing those who merit authorship. This article describes a research project led by the Medical Publishing Insights and Practices (MPIP) Initiative to identify current challenges when determining authorship for industry-sponsored clinical trials and develop an improved approach to facilitate decision-making when recognizing authors from related publications. A total of 498 clinical investigators, journal editors, publication professionals and medical writers were surveyed to understand better how they would adjudicate challenging, real-world authorship case scenarios, determine the perceived frequency of each scenario and rate their confidence in the responses provided. Multiple rounds of discussions about these results with journal editors, clinical investigators and industry representatives led to the development of key recommendations intended to enhance transparency when determining authorship. These included forming a representative group to establish authorship criteria early in a trial, having all trial contributors agree to these criteria and documenting trial contributions to objectively determine who warrants an invitation to participate in the manuscript development process. The resulting Five-step Authorship Framework is designed to create a more standardized approach when determining authorship for clinical trial publications. Overall, these recommendations aim to facilitate more transparent authorship decisions and help readers better assess the credibility of results and perspectives of the authors for medical research more broadly. Please see related article: http://www.biomedcentral.com/1741-7015/12/214.

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Optically stimulated luminescence (OSL) 'dot' dosemeters (manufactured by Landauer®) are reported to have a high degree of environmental stability, high level of sensitivity and provide wide range of dose measuring capabilities from 0.05 mGy to 100 Gy. The optical read out method is fast and relatively simple and permits repeated read out, but few studies have been performed about its application in monitoring radiation in the environment. This study was initiated to independently test the performance of OSL dot dosemeters for the application of measuring doses of radiation in the outdoor environment. Testing was performed in the laboratory to evaluate reproducibility and stability and in the field to evaluate accuracy relative to calibrated high-pressure ionisation chambers. The results showed that OSL dot dosemeters had good reproducibility and stability in both laboratory and field tests and met the performance requirements of standards of the American National Standards Institute.

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Polymethyl methacrylate (PMMA) is a useful material for dosimetry phantoms in many ways including approximate tissue equivalence, stability, accessibility and ease of use. However, recent studies indicate that PMMA may have some unanticipated variation in backscatter from one phantom to another. While the reasons behind the variations have not been identified, it has been demonstrated that the backscatter from one phantom to another may vary by as much as 15%, resulting in a dosemeter response variation of as much as 5%. This unexpected contribution to uncertainty in delivered dose to a dosemeter may be quite large compared to the normally estimated uncertainty, potentially causing problems with calibration and performance testing. This paper includes data supporting the differences in backscatter among phantoms, and results from tests on the phantoms performed in an effort to identify possible causes.

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Lung cancer is a disease that is almost entirely caused by smoking; hence, it is almost totally preventable. Yet there are a small percentage of cases, perhaps as many as 5 to 15%, where there are other causes. Risk factors identified for this other group include passive smoking, occupational exposure to certain chemicals and ionizing radiation, diet, and family history of cancer. In the United States cigarette smoking is on the decline among adults, occupational exposures are being reduced, and people are being made more aware of appropriate diets. These changes are gradually resulting in a reduced risk for this disease. Lung cancer in the U.S. may, therefore, eventually become largely a disease of the past. It remains important, however, to continue to study the cause(s) of lung cancer in non-smokers, particularly never smokers. Because of our interest in the effects of residential radon exposure on the development of lung cancer in non-smokers, we conducted a critical review of the scientific literature to evaluate this issue in detail. Strict criteria were utilized in selecting studies, which included being published in a peer reviewed journal, including non-smokers in the studied populations, having at least 100 cases, and being of case-control design. A total of 12 individual studies were found that met the criteria, with 10 providing some information on non-smokers. Most of these studies did not find any significant association between radon and lung cancer in non-smokers. Furthermore, data were not presented in sufficient detail for non-smokers in a number of studies. Based on the most recent findings, there is some evidence that radon may contribute to lung cancer risk in current smokers in high residential radon environments. The situation regarding the risk of lung cancer from radon in non-smokers (ex and never) is unclear, possibly because of both the relatively limited sample size of non-smokers and methodological limitations in most of the individual studies. A summary of these studies is provided concerning the state of knowledge of the lung cancer risk from radon, methodological problems with the residential studies, the need for the provision of additional data on non-smokers from researchers, and recommendations for future research in non-smokers.

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