Histopathologic Analysis of Lung Cancer Incidence Associated with Radon Exposure among Ontario Uranium Miners

Although radon is a well-established contributor to lung cancer mortality among uranium miners, the effects of radon decay products on different histopathologies of lung carcinoma are not well established. Using a retrospective cohort design, this study aims to examine the risks of lung cancer by histological subtypes associated with exposure to radon decay products among the Ontario Uranium Miners cohort. Cases were stratified by histological groups, and associated risks were estimated for cumulative radon exposure after adjustment for attained age and calendar period. Between 1969 and 2005, 1274 incident cases of primary lung cancer were identified. Of these, 1256 diagnoses (99%) contained information on histology. Squamous cell carcinoma was most common (31%), followed by adenocarcinoma (20%), large cells (18%), small cell lung carcinoma (14%), and other or unspecified cell types (17%). Of the histological sub-groups, small cell lung carcin

Characterisation of the shear stud-concrete connection using finite element analysis

The degradation of the connection between shear studs and concrete is a complicated phenomenon that depends on many factors, including; interfacial properties, concrete crushing and steel yielding. The purpose of this paper is to outline the scope and methodology of the research project being undertaken to characterise the shear stud-concrete interface of a composite beam using finite element analysis. A mesoscopic model will be created for a section of the interface. With the use of a multi-scale approach, the mesoscopic model will be incorporated into a global model. The influence of steel roughness and mechanical properties will be included. Concrete is to be modelled as heterogeneous, comprising discrete regions of aggregate, cement matrix, and an interfacial transition zone (ITZ). The effect of the ITZ will be taken into account using a zero thickness cohesive element. Experimental testing using a push-up rig is to be conducted to verify the numerical models. The ultimate aim is to develop a simplified representation of the shear stud-concrete interface that can be used in a large scale finite element model of a composite member to correctly capture the behaviour of the shear stud-concrete interface in the elastic and inelastic state

Ontario Uranium Miners Cohort Study Report

This is the final report prepared for the Canadian Nuclear Safety Commission.This study is an updated analysis of mortality and cancer incidence for a cohort of Ontario uranium miners exposed to radon decay products (RDP). The cohort had been created previously using the Ontario Mining Master File (MMF) (1954-1986) and data from the National Dose Registry (NDR) (1954-2004). For this update the mortality follow-up of the cohort between 1954 and 2007 was expanded by linking to records in the Canadian Mortality Database (CMDB). Similarly cancer incidence from 1969 and 2005 was ascertained by linking to the Canadian Cancer Database (CCDB) at Statistics Canada. Annual exposure to radon, in working level months (WLMs), was available for each cohort member.Canadian Nuclear Safety Commissio

Interfacial fracture of polymer foam-metal composites at micro-scale using finite element analysis

Foam-metal composites are being increasingly used in a variety of applications. One important aspect in the structural integrity of foam-metal interface is the ability to resist failure around the interface whilst ensuring required load bearing capacity. This study investigated the mechanical and failure behaviour at the interface region at micro scale. The foam-metal composite consisted of polyurethane foam directly adhered to a galvanised steel face sheet. Optical, scanning electron and atomic force microscopy were used to examine the interface geometry and to obtain a realistic surface profile for use in a finite element (FE) model. Finite element analysis (FEA) was used to study the effects of different interfacial roughness profiles on mechanical interlocking and modes of failure, which are directly related to interfacial strength. A set of finite element models of idealised surface pairs of different geometries and dimensions were developed based on the microscopic observations at the foam-metal interface. The finite element modelling results show that the micro- scale roughness profile at the foam-metal interface causes mechanical interlocking and affects the stress field at the scale of the interface surface roughness, which consequently governs the specific failure mode and the relative proportion of the cohesive to adhesive failure in the interface region for a given foam-metal interface. It was found that the aspect ratio (relative width and height) and width ratio (relative spacing) of roughness elements have a significant effect on the stresses and deformations produced at the interface and consequently control the modes (cohesive or adhesive) of failure

Cancer incidence and mortality from exposure to radon progeny among Ontario uranium miners

Objectives The study objectives were to extend the follow-up of the Ontario uranium miners cohort, one of the largest cohorts of uranium miners with low cumulative exposures, to examine the relationship between radon exposure and lung cancer mortality and, for the first time incidence, and address gaps in the literature, including dose-response relationship between radon exposure and other cancer sites, and non-cancer mortality. Methods The cohort of mine and mill workers was created using data from Canada's National Dose Registry and the Ontario Mining Master File. The follow-up for the cohort was recently extended for mortality (1954- 2007) and for the first time includes cancer incidence (1969-2005). The Poisson regression was used to estimate relative risks (RR) and excess relative risks (ERR) and their 95% CIs with levels of cumulative radon exposure. Results The cohort consisted of 28 546 male miners with a mean cumulative radon exposure of 21.0 working level months (WLM). An increased risk of lung cancer and a dose-response relationship was observed with cumulative radon exposure. Miners exposed to >100 WLM demonstrated a twofold increase in the risk of lung cancer incidence (RR=1.89, CI 1.43 to 2.50) compared with the non-exposed group, and a linear ERR of 0.64/ 100 WLM (CI 0.43 to 0.85), with similar results observed for mortality. No association was observed for other cancer sites (stomach, leukaemia, kidney and extrathoracic airways) or non-cancer sites (cardiovascular diseases) with increasing cumulative exposure to radon. Conclusions These findings suggest no increased risk of cancer sites other than lung or non-cancer mortality from relatively low cumulative exposure to radon

Radon and cancer mortality among underground uranium miners in the Příbram region of the Czech Republic

OBJECTIVES: This study aims to estimate the association between radon and cancers other than lung among a large contemporary cohort of uranium miners. METHODS: Annual occupational radon exposure was estimated based on a worker’s duration of underground mining in a year and estimates of potential alpha energy of radon progeny in their location of work. Cancer mortality over the period 1977–1992 was ascertained for a cohort of 16,434 underground uranium miners employed in the Czech Republic between 1946 and 1992. Poisson regression was used to estimate relationships between cumulative radiation exposure (in working level months, WLM) and site-specific cancer mortality. RESULTS: Radon is positively associated with lung cancer mortality (Excess relative rate (ERR) per 100WLM = 0.2; 95%CI: 0.10, 0.37). The best fit of the dose-response relationship between radon and lung cancer mortality was linear and estimates of radon-lung cancer associations varied by windows of time-since-exposure. Positive associations between radon and several types of cancer other than lung cancer were identified, notably Chronic Lymphocytic Leukemia (CLL) (ERR/100WLM = 0.24; 95%CI ND, 5.10) and extrathoracic cancer (ERR/100WLM = 0.12; 95%CI: (ND, 0.69). We observed no associations between radon and stomach cancer, nor between radon an several hematopoietic cancer subtypes. CONCLUSIONS: This study confirms the established radon-lung cancer association and suggests that radon may also be associated with other types of cancer mortality. Further investigations of extrathoracic and CLL cancer, with the aim of obtaining more precise estimates, are warranted to understand associations between radon and cancers other than lung