197 research outputs found
MSJ783343_supplementary_tables – Supplemental material for Lifetime exposure to ultraviolet radiation and the risk of multiple sclerosis in the US radiologic technologists cohort study
No full textSupplemental material, MSJ783343_supplementary_tables for Lifetime exposure to ultraviolet radiation and the risk of multiple sclerosis in the US radiologic technologists cohort study by Lisa G Gallagher, Sindana Ilango, Annette Wundes, Gary A Stobbe, Katherine W Turk, Gary M Franklin, Martha S Linet, D Michal Freedman, Bruce H Alexander and Harvey Checkoway in Multiple Sclerosis Journal</p
Bias in occupational epidemiology studies.
No full textThe design of occupational epidemiology studies should be based on the need to minimise random and systematic error. The latter is the focus of this paper, and includes selection bias, information bias and confounding. Selection bias can be minimised by obtaining a high response rate (and by appropriate selection of the control group in a case-control study). In general, it is important to ensure that information bias is minimised and is also non-differential (for example, that the misclassification of exposure is not related to disease status) by collecting data in a standardised manner. A major concern in occupational epidemiology studies usually relates to confounding, because exposure has not been randomly allocated, and the groups under study may therefore have different baseline disease risks. For each of these types of bias, the goal should be to avoid the bias by appropriate study design and/or appropriate control in the analysis. However, it is also important to attempt to assess the likely direction and strength of biases that cannot be avoided or controlled
Critical review and synthesis of the epidemiologic evidence on formaldehyde exposure and risk of leukemia and other lymphohematopoietic malignancies
No full textPurpose Recent epidemiologic studies indicate elevated risks for some lymphohematopoietic malignancies (LHM) related to formaldehyde exposure. We performed a systematic review of literature to assess the strength and consistency of associations. Methods We summarized published literature in the PubMed database of the National Library of Medicine during 1966-2012. Literature was categorized according to study design and population: industrial cohort studies, professional cohort studies, and population-based case- control studies. Results Findings from occupational cohort and population-based case-control studies were very inconsistent for LHM, including myeloid leukemia. Apart from some isolated exceptions, relative risks were close to the null, and there was little evidence for dose-response relations for any of the LHM. Conclusions At present, there is no consistent or strong epidemiologic evidence that formaldehyde is causally related to any of the LHM. The absence of established toxicologicalmechanisms further weakens any arguments for causation. To be informative, future epidemiologic research should improve on formaldehyde exposure assessment and apply modern diagnostic schemes for specific LHM. © 2012 Springer Science+Business Media B.V
Night shift work and lung cancer among female textile workers in Shanghai, China
No full textThesis (Master's)--University of Washington, 2012Background: In 2007, the International Agency for Research on Cancer classified shift work that involves circadian disruption as a probable human carcinogen. Nighttime chronodisruption has been shown to decrease concentrations of melatonin, a presumed antineoplastic hormone. Based on this biologic plausibility, our objective was to investigate an association between night shift work and lung cancer risk among Chinese female textile workers. Methods: We conducted a case-cohort study nested within a cohort of 267,400 female textile workers employed by the Shanghai Textile Industry Bureau. Participants were followed for lung cancer incidence from January 1, 1989 through December 31, 2006. The comparison group consisted of a Subcohort (n=4807) based on a 5-year frequency age-matched to all-cancer cases in the cohort. We examined an association between exposure to cumulative night shift work and lung cancer outcomes (n=1423) adjusting for age, smoking, and parity. Hazard ratios (HRs) using Cox proportional hazards model with robust variance estimated relative risks with 95% confidence intervals (CIs). Results: Surprisingly, cumulative years of working rotating night shifts and cumulative nights of rotating shiftwork were both associated with moderately reduced risk of lung cancer risk, although the trends were not statistically significant (Ptrend of 0.19 and 0.28, respectively). The hazard ratios, adjusted for age and smoking history, for the lowest categories of cumulative years working rotating night shifts (HR = 0.78, 95% CI = 0.64 to 0.95) and cumulative rotating nights worked (HR = 0.79, 95% CI = 0.65 to 0.96) were both statistically significant. Similar results were obtained when exposures were lagged by 20 years to account for disease latency. Parity was not included in the final model as it did not significantly alter the relative risk estimates. Conclusions: Long-term rotating nighttime shift work appears to demonstrate a decreased risk of lung cancer among Chinese female textile workers compared to non-exposed although trend was not statistically significant. Further investigation on potential factors not yet measured may elucidate a more definitive association of this effect
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The Prevalence of Sleep Disordered Breathing and Associated Risk Factors in Acute Congestive Heart Failure Patients in Mozambique
No full textSleep disordered breathing (SDB) is common in patients with congestive heart failure (CHF), yet these conditions have not been well characterized in developing countries; this includes Mozambique, a sub-Saharan African country. Diagnosing SDB in individuals with CHF is important because, in theory, treating SDB in these patients may improve symptoms associated with and caused by CHF. Between September of 2014 and April of 2017, 159 hospitalized patients with acute congestive heart failure were referred to the Maputo specialized cardiology unit and consecutively enrolled, utilizing a convenience sampling method, in a cross-sectional observation study in Mozambique, East Africa. Based on inclusion criteria, we analyzed the occurrence of SDB and associated risk factors in 153 patients with CHF (64 male, 95 female) in the Mozambique hospitalized patient population. The overall occurrence of SDB in patients with CHF was 66.0%. Of patients with SDB, those with central sleep apnea were 67.3%. Males were 27% more likely to have SDB than females; no differences in age. Furthermore, those with a low left ventricular ejection fraction (below 55%) were 4.7 times more likely to have SDB, compared to those who did not. More specifically, those with a low left ventricular ejection fraction were more likely to have central sleep apnea, compared to those that do not.We conclude that demographic and background information, supplemented by a few simple laboratory tests, may allow physicians to screen for SDB conditions in patients with CHF, and the need for the development of diagnostic tools for this patient population in Mozambique
Exposure Assessment and Inflammatory Response Among Workers Producing Calcium Carbonate Nanomaterials
No full textThesis (Ph.D.)--University of Washington, 2013Problem: Nanotechnology is one of the most rapidly growing fields of science and engineering, and its applications have expanded to numerous research and industrial sectors, from consumer products to medicine to energy. Nano-materials and nanotechnology promise substantial benefits. However, there are many uncertainties and concerns regarding human health and the environment. Numerous toxicological studies on animals and cells in vitro have demonstrated that nanomaterials could cause various adverse health effects, including inflammation, oxidative stress, fibrosis and mutagenesis in the lungs, and cardiovascular and nervous system impairment. Objectives: The overall objective of this study was to characterize particulate exposures in a calcium carbonate nanoparticle manufacturing facility, investigate possible respiratory and cardiovascular effects, and explore the plausibility of an inflammatory mechanism. The associations between exposure level and various health outcomes were investigated. Methodology: Each job was characterized by mass, number and surface area concentration. Job classification was performed based on ranking of the exposure level and statistical models. Lung function tests, exhaled NO and blood pressure (BP) were measured before and after the workshift in the year of 2011. Inflammatory cytokines from induced sputum were measured cross-sectionally in the year of 2011. Data of lung function tests and blood pressure were collected cross-sectionally in the year of 2012. The associations between each exposure metric and health measures in 2012 were investigated. Only mass concentration was linked to both 2011 and 2012 health outcomes. Results: The sampling and analytic methodology used in the study presents the potential to characterize nanoparticle exposure for a variety of operational processes. We found the highest mass exposure occurred at bagging job whereas the highest number and surface area concentration was found at modification. Modification is thought to be the primary emission source. It is discovered nanoparticles in the size range of 20-300nm dominate in this workplace, which consists of 90-98% of particle counts in the respirable fraction. Based on the sampling results from 2012, there was a strong relationship between number concentration in 5-25um range and the respirable mass concentration (r= 0.908); however, no such correlation was found between number concentration in nanoscale and respirable mass (r= 0.018). The deposited surface area in TB (r=0.66) and alveolar region (r=0.46) was modestly correlated with number concentration of particles in the nanoscale. A reduced FEV1 and increased BP were consistently found among medium-mass exposure compared to low-mass exposure, however no statistical significance was found. When comparing the four exposure metrics, we found number concentration and surface area concentration in general produce effects in similar direction, however opposite to mass concentration. Such observation is consistent with the correlation among these exposure metrics. Airway inflammatory responses presented a dose-response relationship using mass as exposure metric. The concentrations of IL1b (p=0.043) and IL8 (p=0.008) in sputum among high mass-exposure group were statistically greater than that in low-mass exposure group. It suggested the inflammatory responses were associated with mass concentration of inhaled nanoparticle particles, which are mainly made up by agglomerated form of nanoparticles. At current stage, with limited understanding of the toxicological perspective of nanoparticle, a complete exposure assessment in nanoparticle facility needs to be conducted in both bulk- and nano-form
Occupational Risk Factors for Pancreatic Cancer Among Female Shanghai, China Textile Workers: An Updated Nested Case-cohort Study
No full textThesis (Master's)--University of Washington, 2012Pancreatic cancer is of particular public health importance given its disproportionate contribution to cancer death. In the United States pancreatic cancer is the fourth most common cause of cancer-related death. Yet occupational risk factors for pancreatic cancer have been inadequately studied in large populations, particularly among textile workers. These occupational exposures represent a potential target for reduction in pancreatic cancer death. A prior nested case-cohort study of 180 incident cases and 3188 non-cases investigated occupational risk factors for pancreatic cancer in a Shanghai, China cohort of 267,400 female textile workers followed from 1989-1998. The findings indicated dose-related reduced risks associated with endotoxin, a contaminant of cotton dust. We have since updated that Shanghai cohort with an additional eight years of data (now including 1989-2006), and repeated the case-cohort analysis to look for associations between pancreatic cancer and three groups of exposures: metals, solvents, and endotoxin. We did not find much evidence of an association between estimated endotoxin exposures and the risk of developing pancreatic cancer. We did not find strong evidence of association between metals and solvents exposures and the risk of developing pancreatic cancer
Outdoor Occupational History and Risk of Parkinson Disease: a Case-Control Study
No full textThesis (Master's)--University of Washington, 2012Introduction: A role for antioxidants in prevention of Parkinson disease has been proposed, however, epidemiologic evidence supporting this assertion has been inconclusive. Ninety percent of vitamin D in adults is produced in vivo related to ultraviolet type B exposure. This creates a plausible role for outdoor work as a strong surrogate for vitamin D in studies related to neurodegenerative disease. Design and Setting: We investigated this association among non-Hispanic Caucasians in Washington state using 447 incident Parkinson disease cases diagnosed between 1992-2008, and 578 neurologically normal controls, frequency matched by age and sex. Material and Methods: Subjects' work histories were obtained by in-person interviews, and a validated method was used to classify each occupation up to 10 years prior to diagnosis (cases)/reference (controls) according to relative time spent outdoors. Research participants were categorized as having exclusively indoor, a combination of indoor/outdoor, or exclusively outdoor occupations using job title. Length of time employed in each occupation was also used to estimate the lifetime duration of any outdoor work, and the maximal and typical levels of outdoor work. Results: Classified by job title and without the inclusion of a 10-year lag time, Odds ratios and 95% confidence intervals from unconditional logistic regression adjusting for age, sex, and smoking were as follows: (> 0 - 75% workday outdoors) 0.86 (0.60-1.23), compared to workers who labored exclusively indoors. Classified by job title and incorporating a 10-year lag time, Odds ratios and 95% confidence intervals from unconditional logistic regression adjusting for age, sex, and smoking were as follows: (> 0 - 75% workday outdoors) 0.85 (0.60-1.22), compared to workers who labored exclusively indoors. Conclusions: Our findings suggest that workers who spend at least part of their day outdoors have a lower risk of Parkinson disease as compared to workers who labor exclusively indoors. This supports the hypothesis that ultraviolet type B exposure acting as an ecological surrogate for vitamin D may provide a protective effective for the development of Idiopathic Parkinson Disease
Selecting appropriate study designs to address specific research questions in occupational epidemiology.
No full textUNLABELLED: Various epidemiological study designs are available to investigate illness and injury risks related to workplace exposures. The choice of study design to address a particular research question will be guided by the nature of the health outcome under study, its presumed relation to workplace exposures, and feasibility constraints. This review summarises the relative advantages and limitations of conventional study designs including cohort studies, cross-sectional studies, repeated measures studies, case-control (industry- and community-based) studies, and more recently developed variants of the nested case-control DESIGN: case-cohort and case-crossover studies
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