14 results on '"Megan J, Leonhard"'
Search Results
2. A 37-year Update on Mortality Patterns in an Expanded Cohort of Vermont Talc Miners and Millers
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Fionna Mowat, Tiffani A. Fordyce, Suresh H. Moolgavkar, and Megan J. Leonhard
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Adult ,Male ,Respiratory Tract Diseases ,Population ,Mining ,Occupational safety and health ,Young Adult ,Cause of Death ,Neoplasms ,Humans ,Medicine ,Young adult ,education ,Occupational Health ,Aged ,Retrospective Studies ,Cause of death ,Aged, 80 and over ,education.field_of_study ,business.industry ,Mortality rate ,Public Health, Environmental and Occupational Health ,Retrospective cohort study ,Middle Aged ,Confidence interval ,Occupational Diseases ,Talc ,Cohort ,business ,Follow-Up Studies ,Vermont ,Demography - Abstract
The aim of this study was to update a cohort of Vermont talc workers to include 37 additional years of follow-up time.Standardized mortality ratios (SMR) and 95% confidence intervals (CIs) were calculated for 70+ causes of death. US population mortality rates were used as reference.All-cause mortality was 30% higher than the US population (SMR 133.4, 95% CI, 119.7 to 148.3). Significant elevations occurred in nonmalignant respiratory disease (NMRD) (SMR 273.0, 95% CI, 210.2 to 348.6) and other nonmalignant respiratory disease (ONMRD) (SMR 413.1, 95% CI, 287.7 to 574.5). ONMRD was elevated across all length of employment categories and a test for linear trend was significant (P = 0.007).This study provides further evidence that excess deaths among Vermont talc workers are due largely to excess mortality from NMRD; there is no evidence of increased risk of respiratory cancer.
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- 2019
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3. Letter to the Editor: Response to Finkelstein Re
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Tiffani Ann, Fordyce, Megan J, Leonhard, Fionna, Mowat, and Suresh, Moolgavkar
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Cohort Studies ,Talc ,Vermont - Published
- 2020
4. A Systematic Review of Cost-Effectiveness Analyses of Left Ventricular Assist Devices: Issues and Challenges
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Prem A. Midha, Jasmine D. Patel, Megan J. Leonhard, and Jordana K. Schmier
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Male ,Economics and Econometrics ,medicine.medical_specialty ,Cost effectiveness ,Cost-Benefit Analysis ,MEDLINE ,Health administration ,Ventricular Dysfunction, Left ,03 medical and health sciences ,0302 clinical medicine ,Societal perspective ,Humans ,Medicine ,030212 general & internal medicine ,Intensive care medicine ,Bridge to transplant ,Health economics ,Cost–benefit analysis ,business.industry ,030503 health policy & services ,Health Policy ,Prostheses and Implants ,General Medicine ,Female ,0305 other medical science ,business ,Destination therapy - Abstract
Advanced heart failure (HF) can be treated conservatively or aggressively, with left ventricular assist devices (LVADs) and heart transplant (HT) being the most aggressive strategies. The goal of this review was to identify, describe, critique and summarize published cost-effectiveness analyses on LVADs for adults with HF. We conducted a literature search using PubMed and ProQuest DIALOG databases to identify English-language publications from 2006 to 2017 describing cost-effectiveness analyses of LVADs and reviewed them against inclusion criteria. Those that met criteria were obtained for full-text review and abstracted if they continued to meet study requirements. A total of 12 cost-effectiveness studies (13 articles) were identified, all of which described models; they were almost evenly split between those examining LVADs as destination therapy (DT) or as bridge to transplant (BTT). Studies were Markov or semi-Markov models with one- or three-month cycles that followed patients until death. Inputs came from a variety of sources, with the REMATCH trial and INTERMACS registry common clinical data sources, although some publications also used data from studies at their own institutions. Costs were derived from standard sources in many studies but from individual hospital data in some. Inputs for health utilities, which were used in 11 of 12 studies, were generally derived from two studies. None of the studies reported a societal perspective, that is, included non-medical costs such as caregiving. No study found LVADs to be cost effective for DT or BTT with base case assumptions, although incremental cost-effectiveness ratios met thresholds for cost effectiveness in some probabilistic analyses. With constant improvements in LVADs and expanding indications, understanding and re-evaluating the cost effectiveness of their use will be critical to making treatment decisions.
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- 2018
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5. Exposure of laboratory animals to small air ions: a systematic review of biological and behavioral studies
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Megan J. Leonhard, Amy Lavin Williams, and William H. Bailey
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0301 basic medicine ,Ionization ,lcsh:Medical technology ,Atmospheric ions ,Biomedical Engineering ,Physiology ,Review ,Corona ions ,Positive ion ,ARRIVE ,Space charge ,Ion ,Biomaterials ,03 medical and health sciences ,Animals, Laboratory ,Behavioral study ,Animals ,Medicine ,Radiology, Nuclear Medicine and imaging ,Adverse effect ,Physiological Phenomena ,Negative ion ,Air ions ,Behavior, Animal ,Toxicity ,Radiological and Ultrasound Technology ,Human studies ,Animal ,Mechanism (biology) ,business.industry ,Air ,Confounding ,Respiratory infection ,General Medicine ,030104 developmental biology ,lcsh:R855-855.5 ,business - Abstract
Background Air ions are molecules of air that have become ionized—that is, they have either lost or gained an electrical charge. Past speculation has suggested that exposure to positive air ions may be harmful to one’s health, while exposure to negative air ions may be associated with beneficial health effects. Air ions arise from natural sources as well as direct-current transmission lines and commercial ionizers. Several recent clinical studies have suggested therapeutic effects of air ions on various types of depression at exposure levels 10- to 1000-fold higher than most previous human studies. The aim of this study was to assess the evidence from studies of laboratory animals for beneficial or adverse effects of air ions on health. Methods Sixty-two studies (1935–2015) in nine topics areas were evaluated for quality and potential systematic bias by ARRIVE guidelines. Standardized mean differences or proportional differences between exposed and control groups were computed for 44 studies to quantitatively assess the strength of the evidence for exposure-related effects. Results Many of the studies were conducted before 1990 and exhibited various reporting and methodological deficiencies, including small sample size, failure to control for the influence of potential confounding variables, lack of randomized assignment to treatment groups and blinded analyses, and statistical errors relating to treating group-exposed animals as individuals. The highest quality studies consistently reported no effects of exposure on any of the endpoints examined. There were no evident dose–response relationships within or across studies. Conclusions Experimental studies of laboratory animals exposed to positive and negative air ions for minutes to years over a five-log unit range of intensities did not suggest any consistent or reliable effects on measures of behavior, learning and memory, neurotransmitters, tracheal function, respiratory infection, cardiovascular function, reproduction and growth, carcinogenesis, or other health endpoints. These data do not provide evidence of adverse or beneficial effects of air ion exposure on health, and did not suggest any biological mechanism of interaction, except perhaps for mechanosensory stimulation of body surfaces by static electric fields at high air ion concentrations. Electronic supplementary material The online version of this article (10.1186/s12938-018-0499-z) contains supplementary material, which is available to authorized users.
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- 2018
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6. A critical review of developmental exposure to particulate matter, autism spectrum disorder, and attention deficit hyperactivity disorder
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Tiffani A. Fordyce, Ellen T. Chang, and Megan J. Leonhard
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Male ,Environmental Engineering ,Autism Spectrum Disorder ,010501 environmental sciences ,behavioral disciplines and activities ,01 natural sciences ,03 medical and health sciences ,0302 clinical medicine ,mental disorders ,Humans ,Medicine ,Attention deficit hyperactivity disorder ,Prospective cohort study ,0105 earth and related environmental sciences ,Exposure assessment ,business.industry ,Small sample ,Environmental Exposure ,General Medicine ,Environmental exposure ,medicine.disease ,Attention Deficit Disorder with Hyperactivity ,Autism spectrum disorder ,Attention deficit ,Female ,Particulate Matter ,business ,030217 neurology & neurosurgery ,Cohort study ,Clinical psychology - Abstract
Autism spectrum disorder (ASD) and attention deficit (hyperactivity) disorder (ADD/ADHD) are key focuses of current health research due to their increasing prevalence. The objective of this systematic literature search and critical review was to evaluate whether the human epidemiologic data indicate a pattern of association between ASD or ADD/ADHD and developmental exposure to particulate matter (PM), with a focus on exposures encountered before the age of three. A MEDLINE and EMBASE search was conducted; following preliminary and full-text screening, 14 relevant articles were identified for review. Three of the 14 studies were prospective cohort studies evaluating exposure to PM10; 11 studies had a case-control design. There was no consistent association between developmental PM exposure and ASD across the three of the cohort studies. Seven of the case-control studies examined the relationship between PM2.5 and/or PM10 and ASD; four examined the relationship between developmental diesel PM exposure and ASD. Overall, there was low external consistency in results among studies of PM2.5/PM10 and ASD, with some reporting high internal consistency without significant associations, others showing associations with high internal consistency for specific exposure windows only (e.g., third trimester), and still others showing high consistency for moderate to strong associations between PM and ASD. The majority of studies reporting significant results had low effect sizes in conjunction with small sample sizes. The four studies of diesel PM and ASD also had low external consistency of results. Only one study evaluated associations with ADD/ADHD, and it found no significant associations with PM10. The inconsistent findings across studies of developmental exposure to PM and ASD may be attributed to differences in the study populations, exposure assessments, outcome assessments, or chance. Further research is needed to understand the underlying biological mechanisms that lead to ASD and ADD/ADHD and how PM might be involved in those mechanisms, if at all. High-quality epidemiologic studies are also needed to conclusively determine whether developmental PM exposure is a causal factor for ASD or ADD/ADHD, with focus on a well-developed exposure assessment.
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- 2017
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7. Letter to the Editor: Response to Finkelstein Re: the Fordyce et al. Vermont Talc Miners and Millers Cohort Study Update
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Tiffani A. Fordyce, Fionna Mowat, Suresh H. Moolgavkar, and Megan J. Leonhard
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medicine.medical_specialty ,Letter to the editor ,business.industry ,General surgery ,Public Health, Environmental and Occupational Health ,medicine ,MEDLINE ,business ,Finkelstein's test - Published
- 2020
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8. Letter to the Editor: Misrepresentation by Egilman et al. of the Fordyce et al. (2019) Vermont Talc Miners and Millers Cohort Study Update
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Tiffani A. Fordyce, Fionna Mowat, Megan J. Leonhard, and Suresh H. Moolgavkar
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medicine.medical_specialty ,Letter to the editor ,business.industry ,Public Health, Environmental and Occupational Health ,Cohort Studies ,Occupational Diseases ,Misrepresentation ,Talc ,Family medicine ,Occupational Exposure ,medicine ,Humans ,business ,Cohort study ,Vermont - Published
- 2019
9. An analysis of fatal and non-fatal injuries and injury severity factors among electric power industry workers
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Megan J. Leonhard, Lovely Krishen, Heather N. Watson, Tiffani A. Fordyce, Gabor Mezei, and Ximena Vergara
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education.field_of_study ,medicine.medical_specialty ,business.industry ,Population ,Occupational injury ,Public Health, Environmental and Occupational Health ,Poison control ,Human factors and ergonomics ,medicine.disease ,030210 environmental & occupational health ,Suicide prevention ,Occupational safety and health ,03 medical and health sciences ,0302 clinical medicine ,Workforce ,Emergency medicine ,Injury prevention ,medicine ,030212 general & internal medicine ,education ,business - Abstract
BACKGROUND: The electric power industry represents a unique subset of the U.S. workforce. We aimed to evaluate the relationships between occupational category, nature of injury, and injury severity among electric power industry workers. METHODS: The Occupational Health and Safety Database (1995-2013) was used to calculate injury rates, assess patterns of injury severity, and identify at-risk occupations in this population. RESULTS: Over the surveillance period, a total of 63,193 injuries were reported. Overall, and severe injury rates were 3.20 and 0.52 per 100 employee-years, respectively. The fatal injury rate was 3.29 per 100,000 employee-years. Line workers experienced the highest risk for fatal injuries and second highest for non-fatal severe injuries, following meter readers. The most severe non-fatal injuries were hernia and rupture; multiple injuries; and CTD/RSI. Fatal injuries were most commonly associated with vehicle collisions and contact with electric current. CONCLUSIONS: Industry specific surveillance and interventions tailored to high-risk occupations are needed to further reduce severe injuries in this population. Am. J. Ind. Med. © 2016 Wiley Periodicals, Inc.© 2016 Wiley Periodicals, Inc. Language: en
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- 2016
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10. A systematic literature review of epidemiologic studies of developmental manganese exposure and neurodevelopmental outcomes
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Ellen T. Chang, Anne E. Loccisano, Michael R. Garry, and Megan J. Leonhard
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0301 basic medicine ,Male ,Adolescent ,Intelligence ,Gestational Age ,Toxicology ,Risk Assessment ,03 medical and health sciences ,0302 clinical medicine ,Child Development ,Pregnancy ,Risk Factors ,Medicine ,Humans ,Prospective cohort study ,Child ,Exposure assessment ,Intelligence Tests ,Manganese ,business.industry ,Manganese Poisoning ,Confounding ,Age Factors ,Wechsler Adult Intelligence Scale ,Brain ,Infant ,Environmental exposure ,Adolescent Development ,030104 developmental biology ,Systematic review ,Maternal Exposure ,Child, Preschool ,Prenatal Exposure Delayed Effects ,Bradford Hill criteria ,Female ,Neurotoxicity Syndromes ,Biological plausibility ,business ,030217 neurology & neurosurgery ,Clinical psychology - Abstract
Background Neurotoxic effects of high-level occupational exposure to manganese (Mn) are well established; however, whether lower-level environmental exposure to Mn in early life causes neurodevelopmental toxicity in children is unclear. Methods A systematic literature review was conducted to identify and evaluate epidemiologic studies of specific Mn biomarkers assessed during gestation, childhood, or adolescence in association with neurodevelopmental outcomes, focusing on quantitative exposure-response estimates with specific endpoints that were assessed in multiple independent study populations. Study quality was evaluated using the revised RTI item bank and the Cochrane Risk of Bias tool, and the overall weight of epidemiologic evidence for causality was evaluated according to the Bradford Hill considerations. Results Twenty-two epidemiologic studies were identified that estimated associations between early-life Mn biomarkers and neurodevelopmental outcomes. Seven of these studies provided adjusted estimates for the association with child intelligence assessed using versions of the Wechsler Intelligence Scales for Children; no other specific neurodevelopmental endpoints were assessed in more than three independent study populations each. Among the studies of child intelligence, five studies in four independent populations measured blood Mn, three studies measured hair Mn, and one measured dentin Mn. Overall, cross-sectional associations between Mn biomarkers and measures of child intelligence were mostly statistically nonsignificant but in a negative direction; however, the lone prospective cohort study found mostly null results, with some positive (favorable) associations between dentin Mn and child intelligence. Studies were methodologically limited by their cross-sectional design and potential for confounding and selection bias, as well as unaddressed questions on exposure assessment validity and biological plausibility. Conclusions The statistical associations reported in the few studies of specific Mn biomarkers and specific neurodevelopmental endpoints do not establish causal effects based on the Bradford Hill considerations. Additional prospective cohort studies of Mn biomarkers and validated neurodevelopmental outcomes, and a better understanding of the etiologic relevance of Mn biomarkers, are needed to shed light on whether environmental exposure to Mn causes adverse neurodevelopmental effects in children.
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- 2018
11. Impact of chloroform exposures on reproductive and developmental outcomes: A systematic review of the scientific literature
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Christopher A. Bates, Nelson D. Pace, Ellen T. Chang, John M. DeSesso, Megan J. Leonhard, and Amy Lavin Williams
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Embryology ,Offspring ,Health, Toxicology and Mutagenesis ,Developmental toxicity ,Physiology ,010501 environmental sciences ,Toxicology ,Lower risk ,01 natural sciences ,03 medical and health sciences ,Animal data ,Mice ,0302 clinical medicine ,Pregnancy ,Medicine ,Animals ,Humans ,030212 general & internal medicine ,0105 earth and related environmental sciences ,business.industry ,Reproduction ,Pregnancy Outcome ,Infant, Low Birth Weight ,medicine.disease ,Rats ,Low birth weight ,Fetal Weight ,Maternal Exposure ,Pediatrics, Perinatology and Child Health ,Solvents ,Gestation ,Small for gestational age ,Female ,Chloroform ,medicine.symptom ,business ,Reproductive toxicity ,Developmental Biology - Abstract
AIMS We assessed the animal and epidemiological data to determine if chloroform exposure causes developmental and/or reproductive toxicity. RESULTS AND DISCUSSION Initial scoping identified developmental toxicity as the primary area of concern. At levels producing maternal toxicity in rats and mice, chloroform caused decrements in fetal weights and associated delays in ossification. In a single mouse inhalation study, exposure to a high concentration of chloroform was associated with small fetuses and increased cleft palate. However, oral exposure of mice to chloroform at a dose 4 times higher was negative for cleft palate; multiple inhalation studies in rats were also negative. Epidemiologic data on low birth weight and small for gestational age were generally equivocal, preventing conclusions from being drawn for humans. The animal data also show evidence of very early (peri-implantation) total litter losses at very high exposure levels. This effect is likely maternally mediated rather than a direct effect on the offspring. Finally, the epidemiologic data indicate a possible association of higher chloroform exposure with lower risk of preterm birth (
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- 2017
12. An analysis of fatal and non-fatal injuries and injury severity factors among electric power industry workers
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Tiffani A, Fordyce, Megan J, Leonhard, Heather N, Watson, Gabor, Mezei, Ximena P, Vergara, and Lovely, Krishen
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Adult ,Male ,Injury Severity Score ,Electricity ,Accidents, Occupational ,Humans ,Female ,Middle Aged ,Occupations ,Occupational Injuries ,United States - Abstract
The electric power industry represents a unique subset of the U.S. workforce. We aimed to evaluate the relationships between occupational category, nature of injury, and injury severity among electric power industry workers.The Occupational Health and Safety Database (1995-2013) was used to calculate injury rates, assess patterns of injury severity, and identify at-risk occupations in this population.Over the surveillance period, a total of 63,193 injuries were reported. Overall, and severe injury rates were 3.20 and 0.52 per 100 employee-years, respectively. The fatal injury rate was 3.29 per 100,000 employee-years. Line workers experienced the highest risk for fatal injuries and second highest for non-fatal severe injuries, following meter readers. The most severe non-fatal injuries were hernia and rupture; multiple injuries; and CTD/RSI. Fatal injuries were most commonly associated with vehicle collisions and contact with electric current.Industry specific surveillance and interventions tailored to high-risk occupations are needed to further reduce severe injuries in this population. Am. J. Ind. Med. 59:948-958, 2016. © 2016 Wiley Periodicals, Inc.
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- 2016
13. Injuries among electric power industry workers, 1995-2013
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Gabor Mezei, Ximena Vergara, Tiffani A. Fordyce, Vitaly Volberg, Lovely Krishen, and Megan J. Leonhard
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Adult ,Male ,Occupational group ,Adolescent ,Databases, Factual ,Occupational injury ,Poison control ,Suicide prevention ,Occupational safety and health ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Risk Factors ,Injury prevention ,Forensic engineering ,Medicine ,Humans ,030212 general & internal medicine ,Safety, Risk, Reliability and Quality ,Aged ,business.industry ,Human factors and ergonomics ,Middle Aged ,medicine.disease ,030210 environmental & occupational health ,Occupational Injuries ,United States ,Female ,Electric power industry ,Safety ,business ,Demography ,Power Plants - Abstract
Introduction Workers in the electric power industry face many risks of injury due to the high diversity of work tasks performed in potentially hazardous and unpredictable work environments. Method We calculated injury rates by age, sex, occupational group, and injury type among workers in the Electric Power Research Institute’s (EPRI) Occupational Health and Safety Database (OHSD), which contains recordable injury, medical claims, and personnel data from 18 participating electric power companies from 1995 to 2013. Results The OHSD includes a total of 63,193 injuries over 1,977,436 employee-years of follow-up, for an overall injury rate of 3.20 injuries per 100 employee-years. Annual injury rates steadily decreased from 1995 to 2000, increased sharply in 2001, and subsequently decreased to their lowest rate of 1.31 injuries per 100 employee-years in 2013. Occupations with the highest injury rates were welders (13.56 per 100 employee-years, 95% CI 12.74–14.37), meter readers (12.04 per 100 employee-years, 95% CI 11.77–12.31), and line workers (10.37 per 100 employee-years, 95% CI 10.19–10.56). Males had an overall higher injury rate compared to females (2.74 vs. 1.61 per 100 employee-years) although some occupations, such as meter reader, had higher injury rates for females. For all workers, injury rates were highest for those in the 21 to 30 age group (3.70 per 100 employee-years) and decreased with age. Welders and machinists did not follow this trend and had higher injury rates in the 65 + age group. There were 63 fatalities over the 1995 to 2013 period, with 21 fatalities (33.3%) occurring among line workers. Conclusions Although injury rates have decreased over time, certain high-risk groups remain (i.e., line workers, mechanics, young males, older welders and machinists, and female meter readers). Practical applications Protective measures and targeted safety programs may be warranted to ensure the safety of electric power workers.
- Published
- 2016
14. Leukemias in a Cohort of Crude Oil Workers, 1946–2012
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Tiffani A. Fordyce, Heidi S. Erickson, Megan J. Leonhard, and Kenneth A. Satin
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Traditional medicine ,Epidemiology ,business.industry ,Cohort ,Medicine ,Crude oil ,business - Published
- 2017
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