The Risk of Cancer from CT Scans and Other Sources of Low-Dose Radiation: A Critical Appraisal of Methodologic Quality

AbstractIntroduction: Concern exists that radiation exposure from computerized tomography (CT) will cause thousands of malignancies. Other experts share the same perspective regarding the risk from additional sources of low-dose ionizing radiation, such as the releases from Three Mile Island (1979; Pennsylvania USA) and Fukushima (2011; Okuma, Fukushima Prefecture, Japan) nuclear power plant disasters. If this premise is false, the fear of cancer leading patients and physicians to avoid CT scans and disaster responders to initiate forcedevacuations is unfounded.Study Objective: This investigation provides a quantitative evaluation of the methodologic quality of studies to determine the evidentiary strength supporting or refuting a causal relationshipbetween low-dose radiation and cancer. It will assess the number of higher qualitystudies that support or question the role of low-dose radiation in oncogenesis.Methods: This investigation is a systematic, methodologic review of articles published from 1975–2017 examining cancer risk from external low-dose x-ray and gamma radiation, defined as less than 200 millisievert (mSv). Following the PRISMA guidelines, the authors performed a search of the PubMed, Cochrane, Scopus, and Web of Science databases. Methodologies of selected articles were scored using the Newcastle Ottawa Scale (NOS) and a tool identifying 11 lower quality indicators. Manuscript methodologies were rankedas higher quality if they scored no lower than seven out of nine on the NOS and contained no more than two lower quality indicators. Investigators then characterized articles as supporting or not supporting a causal relationship between low-dose radiation and cancer.Results: Investigators identified 4,382 articles for initial review. A total of 62 articles met all inclusion/exclusion criteria and were evaluated in this study. Quantitative evaluation of the manuscripts’ methodologic strengths found 25 studies met higher quality criteria while 37 studies met lower quality criteria. Of the 25 studies with higher quality methods, 21 out of 25did not support cancer induction by low-dose radiation (P = .0003).Conclusions: A clear preponderance of articles with higher quality methods found no increased risk of cancer from low-dose radiation. The evidence suggests that exposure to multiple CT scans and other sources of low-dose radiation with a cumulative dose up to 100 mSv (approximately 10 scans), and possibly as high as 200 mSv (approximately 20 scans), does not increase cancer risk

Analysis of mortality in a pooled cohort of Canadian and German uranium processing workers with no mining experience.

PurposeLong-term health risks of occupational exposures to uranium processing were examined to better understand potential differences with uranium underground miners and nuclear reactor workers.MethodsA cohort study of mortality of workers from Port Hope, Canada (1950-1999) and Wismut, Germany (1946-2008) employed in uranium milling, refining, and processing was conducted. Poisson regression was used to evaluate the association between cumulative exposures to radon decay products (RDP) and gamma-rays and causes of death potentially related to uranium processing.ResultsThe pooled cohort included 7431 workers (270,201 person-years of follow-up). Mean RDP exposures were lower than in miners while gamma-ray doses were higher than in reactor workers. Both exposures were highly correlated (weighted rho = 0.81). Radiation risks of lung cancer and cardiovascular diseases (CVD) in males were increased but not statistically significant and compatible with risks estimated for miners and reactor workers, respectively. Higher RDP-associated CVD risks were observed for exposures 5-14 years prior to diagnosis compared to later exposures and among those employed <5 years. Radiation risks of solid cancers excluding lung cancer were increased, but not statistically significant, both for males and females, while all other causes of death were not associated with exposures.ConclusionsIn the largest study of uranium processing workers to systematically examine radiation risks of multiple outcomes from RDP exposures and gamma-rays, estimated radiation risks were compatible with risks reported for uranium miners and nuclear reactor workers. Continued follow-up and pooling with other cohorts of uranium processing workers are necessary for future comparisons with other workers of the nuclear fuel cycle

Incidence of thyroid cancer in Golestan province of Iran: Some initial observations

Objectives: The incidence of thyroid cancer is increasing in several countries. The main aim of this study was to find and describe province-specific estimates of incidence in males and females by age groups for thyroid cancer. Methodology: The data used in this study were collected from a cancer registry that was established by Health Deputy of Golestan province for a period of one year (2004), in different age groups. Thyroid cancer data was identified and collected through the eighteen Pathology Laboratory centers (where males and female populations is referred) in Golestan province. Results: A total of 348 females and 409 males cases with cancer representing all sites were identified during the study period. It included seventeen females and five male thyroid cancer patients. In female's thyroid cancer, there were twelve papillary carcinoma (70.6%), two medullary carcinoma, one carcinoma anaplastic and one carcinoma (5.9%). In male's, there were two papillary carcinoma (40%) and one follicular carcinoma. The incidence of thyroid cancer in 70-79 age groups for females and males was the highest and lowest in age group 10-19 years' in females and 30-39 years in males. Conclusion: The incidence of thyroid cancer is higher in females when compared with males as per this one year study. However since this is just one year data, it needs to be studied further to confirm these findings

Secure Method Invocation in JASON

We describe the Secure Method Invocation (SMI) framework implemented for Jason, our Javacard As Secure Objects Networks platform. Jason realises the secure object store paradigm, that reconciles the card-as-storage-element and card-as-processing-element views. In this paradigm, smart cards are viewed as secure containers for objects, whose methods can be called straightforwardly and securely using SMI. Jason is currently being developed as a middleware layer that securely interconnects an arbitrary number of smart cards, terminals and back-office systems over the Internet

The 25th Anniversary of the Chernobyl Accident

The nuclear accident at the Chernobyl plant in 1986 is described and a summary of its immediate effects on people and the environment outlined. Then there is a summary of the important parts of the literature on diseases and deaths resulting from radiation and mortalities to date and the way mortality data became increasingly conservative over the years is discussed. Today, there is still uncertainty about future mortalities dues to long latency periods for many cancers however cancer deaths in Chernobyl affected regions are expected to be similar to non-Chernobyl controls. The major literature on environmental effects on wild species, forests, water and agricultural land are then reported with a brief discussion of remediation work and of current trends. Finally, contemporary perceptions of the Chernobyl accident are described in the context of popular anti-nuclear sentiment that prevailed in 1986, the immense publicity surrounding the accident and the natural tendency of people to exaggerate prospects of unlikely, yet extreme, events.Environmental Economics and Policy,