- Internal Medicine
Chief, Division of General Medical Disciplines, Stanford University (2009 - Present)
Professor of Medicine and Public Health, Yale University (1993 - 2009)
Director, Yale Occupational and Environmental Medicine Program (1980 - 2009)
Associate Professor of Medicine and Epidemiology, Yale University (1985 - 1993)
Assistant Professor of Medicine, Yale University (1980 - 1985)
Honors & Awards
Fifth Place Winner, Westinghouse National Science Talent Search (1967)
Faculty scholar in General Internal Medicine, Henry J. Kaiser Family Foundation (1988)
Member, Elected, Institute of Medicine (National Academy of Sciences) (1997)
Member, Elected, Connecticut Academy of Science & Engineering (2002)
Board Certification: Occupational Medicine, American Board of Preventive Medicine (1986)
Residency:Yale School of Medicine Appointments (1980) CT
Residency:Hospital of Saint Raphael (1984) CT
Board Certification: Internal Medicine, American Board of Internal Medicine (1979)
Medical Education:Yale School of Medicine Appointments (1976) CT
M.D., Yale University, M.D. (1976)
A.B., Harvard College, Philosophy and Physics (1971)
Current Research and Scholarly Interests
Social and environmental determinants of health; role of workplace physical environment and work organization as causes of chronic disease and disability
- Applied Grant-Writing Skills for Community and Clinical Research
MED 253 (Win)
- Independent Studies (5)
Prior Year Courses
Contribution of health status and prevalent chronic disease to individual risk for workplace injury in the manufacturing environment.
Occupational and environmental medicine
2014; 71 (3): 159-166
An 'information gap' has been identified regarding the effects of chronic disease on occupational injury risk. We investigated the association of ischaemic heart disease, hypertension, diabetes, depression and asthma with acute occupational injury in a cohort of manufacturing workers from 1 January 1997 through 31 December 2007.We used administrative data on real-time injury, medical claims, workplace characteristics and demographics to examine this association. We employed a piecewise exponential model within an Andersen-Gill framework with a frailty term at the employee level to account for inclusion of multiple injuries for each employee, random effects at the employee level due to correlation among jobs held by an employee, and experience on the job as a covariate.One-third of employees had at least one of the diseases during the study period. After adjusting for potential confounders, presence of these diseases was associated with increased hazard of injury: heart disease (HR 1.23, 95% CI 1.11 to 1.36), diabetes (HR 1.17, 95% CI 1.08 to 1.27), depression (HR 1.25, 95% CI 1.12 to 1.38) and asthma (HR 1.14, 95% CI 1.02 to 1.287). Hypertension was not significantly associated with hazard of injury. Associations of chronic disease with injury risk were less evident for more serious reportable injuries; only depression and a summary health metric derived from claims remained significantly positive in this subset.Our results suggest that chronic heart disease, diabetes and depression confer an increased risk for acute occupational injury.
View details for DOI 10.1136/oemed-2013-101653
View details for PubMedID 24142977
Incident ischemic heart disease and recent occupational exposure to particulate matter in an aluminum cohort
JOURNAL OF EXPOSURE SCIENCE AND ENVIRONMENTAL EPIDEMIOLOGY
2014; 24 (1): 82-88
Fine particulate matter (PM(2.5)) in air pollution, primarily from combustion sources, is recognized as an important risk factor for cardiovascular events but studies of workplace PM(2.5) exposure are rare. We conducted a prospective study of exposure to PM(2.5) and incidence of ischemic heart disease (IHD) in a cohort of 11,966 US aluminum workers. Incident IHD was identified from medical claims data from 1998 to 2008. Quantitative metrics were developed for recent exposure (within the last year) and cumulative exposure; however, we emphasize recent exposure in the absence of interpretable work histories before follow-up. IHD was modestly associated with recent PM(2.5) overall. In analysis restricted to recent exposures estimated with the highest confidence, the hazard ratio (HR) increased to 1.78 (95% CI: 1.02, 3.11) in the second quartile and remained elevated. When the analysis was stratified by work process, the HR rose monotonically to 1.5 in both smelter and fabrication facilities, though exposure was almost an order of magnitude higher in smelters. The differential exposure-response may be due to differences in exposure composition or healthy worker survivor effect. These results are consistent with the air pollution and cigarette smoke literature; recent exposure to PM(2.5) in the workplace appears to increase the risk of IHD incidence.
View details for DOI 10.1038/jes.2013.47
View details for Web of Science ID 000328604900012
View details for PubMedID 23982120
Process of Care Compliance Is Associated With Fewer Diabetes Complications
AMERICAN JOURNAL OF MANAGED CARE
2014; 20 (1): 41-52
View details for Web of Science ID 000330599000004
High prevalence of chronic kidney disease in a community survey of urban Bangladeshis: a cross-sectional study.
Globalization and health
2014; 10 (1): 9-?
The burden of chronic kidney disease (CKD) will rise in parallel with the growing prevalence of type two diabetes mellitus in South Asia but is understudied. Using a cross-sectional survey of adults living in a middle-income neighborhood of Dhaka, Bangladesh, we tested the hypothesis that the prevalence of CKD in this group would approach that of the U.S. and would be strongly associated with insulin resistance.We enrolled 402 eligible adults (>30 years old) after performing a multi-stage random selection procedure. We administered a questionnaire, and collected fasting serum samples and urine samples. We used the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation to estimate glomerular filtration rate, and sex-specific cut offs for albuminuria: > 1.9 mg/mmol (17 mg/g) for men, and >2.8 mg/mmol (25 mg/g) for women. We assessed health-related quality of life using the Medical Outcomes Study Short Form-12 (SF-12).A total of 357 (89%) participants with serum samples comprised the analytic cohort. Mean age of was 49.5 (± 12.7) years. Chronic kidney disease was evident in 94 (26%). Of the participants with CKD, 58 (62%) had albuminuria only. A participant with insulin resistance had a 3.6-fold increase in odds of CKD (95% confidence interval 2.1 to 6.4). Participants with stage three or more advanced CKD reported a decrement in the Physical Health Composite score of the SF-12, compared with participants without CKD.We found an alarmingly high prevalence of CKD-particularly CKD associated with insulin resistance-in middle-income, urban Bangladeshis.
View details for DOI 10.1186/1744-8603-10-9
View details for PubMedID 24555767
Development of a job-exposure matrix for exposure to total and fine particulate matter in the aluminum industry
JOURNAL OF EXPOSURE SCIENCE AND ENVIRONMENTAL EPIDEMIOLOGY
2014; 24 (1): 89-99
Increasing evidence indicates that exposure to particulate matter (PM) at environmental concentrations increases the risk of cardiovascular disease, particularly PM with an aerodynamic diameter of less than 2.5 μm (PM(2.5)). Despite this, the health impacts of higher occupational exposures to PM(2.5) have rarely been evaluated. In part, this research gap derives from the absence of information on PM(2.5) exposures in the workplace. To address this gap, we have developed a job-exposure matrix (JEM) to estimate exposure to two size fractions of PM in the aluminum industry. Measurements of total PM (TPM) and PM(2.5) were used to develop exposure metrics for an epidemiologic study. TPM exposures for distinct exposure groups (DEGs) in the JEM were calculated using 8385 personal TPM samples collected at 11 facilities (1980-2011). For eight of these facilities, simultaneous PM(2.5) and TPM personal monitoring was conducted from 2010 to 2011 to determine the percent of TPM that is composed of PM(2.5) (%PM(2.5)) in each DEG. The mean TPM from the JEM was then multiplied by %PM(2.5) to calculate PM(2.5) exposure concentrations in each DEG. Exposures in the smelters were substantially higher than in fabrication units; mean TPM concentrations in smelters and fabrication facilities were 3.86 and 0.76 mg/m(3), and the corresponding mean PM(2.5) concentrations were 2.03 and 0.40 mg/m(3). Observed occupational exposures in this study generally exceeded environmental PM(2.5) concentrations by an order of magnitude.
View details for DOI 10.1038/jes.2013.53
View details for Web of Science ID 000328604900013
View details for PubMedID 24022670
Systematic evaluation of environmental and behavioural factors associated with all-cause mortality in the United States National Health and Nutrition Examination Survey.
International journal of epidemiology
2013; 42 (6): 1795-1810
Environmental and behavioural factors are thought to contribute to all-cause mortality. Here, we develop a method to systematically screen and validate the potential independent contributions to all-cause mortality of 249 environmental and behavioural factors in the National Health and Nutrition Examination Survey (NHANES).We used Cox proportional hazards regression to associate 249 factors with all-cause mortality while adjusting for sociodemographic factors on data in the 1999-2000 and 2001-02 surveys (median 5.5 follow-up years). We controlled for multiple comparisons with the false discovery rate (FDR) and validated significant findings in the 2003-04 survey (median 2.8 follow-up years). We selected 249 factors from a set of all possible factors based on their presence in both the 1999-2002 and 2003-04 surveys and linkage with at least 20 deceased participants. We evaluated the correlation pattern of validated factors and built a multivariable model to identify their independent contribution to mortality.We identified seven environmental and behavioural factors associated with all-cause mortality, including serum and urinary cadmium, serum lycopene levels, smoking (3-level factor) and physical activity. In a multivariable model, only physical activity, past smoking, smoking in participant's home and lycopene were independently associated with mortality. These three factors explained 2.1% of the variance of all-cause mortality after adjusting for demographic and socio-economic factors.Our association study suggests that, of the set of 249 factors in NHANES, physical activity, smoking, serum lycopene and serum/urinary cadmium are associated with all-cause mortality as identified in previous studies and after controlling for multiple hypotheses and validation in an independent survey. Whereas other NHANES factors may be associated with mortality, they may require larger cohorts with longer time of follow-up to detect. It is possible to use a systematic association study to prioritize risk factors for further investigation.
View details for DOI 10.1093/ije/dyt208
View details for PubMedID 24345851
Associations between employee and manager gender: impacts on gender-specific risk of acute occupational injury in metal manufacturing
BMC PUBLIC HEALTH
Prior research has shown increased risk of injury for female employees compared to male employees after controlling for job and tasks, but have not explored whether this increased risk might be moderated by manager gender. The gender of one's manager could in theory affect injury rates among male and female employees through their managers' response to an employee's psychosocial stress or through how employees differentially report injuries. Other explanations for the gender disparity in injury experience, such as ergonomic factors or differential training, are unlikely to be impacted by supervisor gender. This study seeks to explore whether an employee's manager's gender modifies the effect of employee gender with regards to risk of acute injury.A cohort of employees and managers were identified using human resources and injury management data between January 1, 2002 and December 31, 2007 for six facilities of a large US aluminum manufacturing company. Cox proportional hazards models were employed to examine the interaction between employee gender and whether the employee had female only manager(s), male only manager(s), or both male and female managers on injury risk. Manager gender category was included as a time varying covariate and reassessed for each employee at the midpoint of each year.The percentage of departments with both female and male managers increased dramatically during the study period due to corporate efforts to increase female representation in management. After adjustment for fixed effects at the facility level and shared frailty by department, manager gender category does not appear to moderate the effect of employee gender (p = 0.717). Manager category was not a significant predictor (p = 0.093) of time to first acute injury. Similarly, having at least one female manager did not modify the hazard of injury for female employees compared to males (p = 0.899) and was not a significant predictor of time to first acute injury (p = 0.601).Prior findings suggest that female manufacturing employees are at higher risk for acute injury compared to males; this analysis suggests that this relationship is not affected by the gender of the employee's manager(s).
View details for DOI 10.1186/1471-2458-13-1053
View details for Web of Science ID 000329295600001
View details for PubMedID 24207014
High prevalence of type 2 diabetes among the urban middle class in Bangladesh
BMC PUBLIC HEALTH
The prevalence of type-2 diabetes and metabolic syndrome are increasing in the developing world; we assessed their prevalence among the urban middle class in Bangladesh.In this cross-sectional survey (n = 402), we randomly selected consenting adults (≥ 30 years) from a middle-income neighborhood in Dhaka. We assessed demography, lifestyle, and health status, measured physical indices and blood pressure and obtained blood samples. We evaluated two primary outcomes: (1) type-2 diabetes (fasting blood glucose ≥ 7.0 mmol/L or hemoglobin A1C ≥ 6.5% (48 mmol/mol) or diabetes medication use) and (2) insulin resistance (type-2 diabetes or metabolic syndrome using International Diabetes Federation criteria).Mean age and Quételet's (body mass) index were 49.4 ± 12.6 years and 27.0 ± 5.1 kg/m²; 83% were married, 41% had ≥12 years of education, 47% were employed, 47% had a family history of diabetes. Thirty-five percent had type-2 diabetes and 45% had metabolic syndrome. In multivariate models older age and family history of diabetes were significantly associated with type-2 diabetes. Older age, female sex, overweight or obese, high wealth index and positive family history of diabetes were significantly associated with insulin resistance. Participants with type-2 diabetes or insulin resistance had significantly poorer physical health only if they had associated cardiovascular disease.The prevalence of type-2 diabetes and metabolic syndrome among the middle class in Dhaka is alarmingly high. Screening services should be implemented while researchers focus on strategies to lessen the incidence and morbidity associated with these conditions.
View details for DOI 10.1186/1471-2458-13-1032
View details for Web of Science ID 000329293000002
View details for PubMedID 24172217
- Preference for wine is associated with lower hip fracture incidence in post-menopausal women BMC WOMENS HEALTH 2013; 13
Health consequences of the 'Great Recession' on the employed: Evidence from an industrial cohort in aluminum manufacturing
SOCIAL SCIENCE & MEDICINE
2013; 92: 105-113
While the negative effects of unemployment have been well studied, the consequences of layoffs and downsizing for those who remain employed are less well understood. This study uses human resources and health claims data from a large multi-site fully insured aluminum company to explore the health consequences of downsizing on the remaining workforce. We exploit the variation in the timing and intensity of layoff to categorize 30 plants as high or low layoff plants. Next, we select a stably employed cohort of workers with history of health insurance going back to 2006 to 1) describe the selection process into layoff and 2) explore the association between the severity of plant level layoffs and the incidence of four chronic conditions in the remaining workforce. We examine four health outcomes: incident hypertension, diabetes, asthma/COPD and depression for a cohort of approximately 13,000 employees. Results suggest that there was an increased risk of developing hypertension for all workers and an increased risk of developing diabetes for salaried workers that remain at the plants with the highest level of layoffs. The hypertension results were robust to a several specification tests. In addition, the study design selected only healthy workers, therefore our estimates are likely to be a lower bound and suggest that adverse health consequences of the 2007-2009 recession may have affected a broader proportion of the population than previously expected.
View details for DOI 10.1016/j.socscimed.2013.04.027
View details for Web of Science ID 000322858200012
View details for PubMedID 23849284
Piecewise exponential models to assess the influence of job-specific experience on the hazard of acute injury for hourly factory workers
BMC MEDICAL RESEARCH METHODOLOGY
An inverse relationship between experience and risk of injury has been observed in many occupations. Due to statistical challenges, however, it has been difficult to characterize the role of experience on the hazard of injury. In particular, because the time observed up to injury is equivalent to the amount of experience accumulated, the baseline hazard of injury becomes the main parameter of interest, excluding Cox proportional hazards models as applicable methods for consideration.Using a data set of 81,301 hourly production workers of a global aluminum company at 207 US facilities, we compared competing parametric models for the baseline hazard to assess whether experience affected the hazard of injury at hire and after later job changes. Specific models considered included the exponential, Weibull, and two (a hypothesis-driven and a data-driven) two-piece exponential models to formally test the null hypothesis that experience does not impact the hazard of injury.We highlighted the advantages of our comparative approach and the interpretability of our selected model: a two-piece exponential model that allowed the baseline hazard of injury to change with experience. Our findings suggested a 30% increase in the hazard in the first year after job initiation and/or change.Piecewise exponential models may be particularly useful in modeling risk of injury as a function of experience and have the additional benefit of interpretability over other similarly flexible models.
View details for DOI 10.1186/1471-2288-13-89
View details for Web of Science ID 000322382600001
View details for PubMedID 23841648
- (De)Personalized Medicine SCIENCE 2013; 339 (6124): 1155-1156
- Selection on Moral Hazard in Health Insurance AMERICAN ECONOMIC REVIEW 2013; 103 (1): 178-219
Impact of daily noise exposure monitoring on occupational noise exposures in manufacturing workers
INTERNATIONAL JOURNAL OF AUDIOLOGY
2013; 52: S3-S8
Despite the use of hearing protection devices (HPDs), noise induced hearing loss (NIHL) remains one of the most prevalent occupational conditions. A new technology allows for daily monitoring of noise exposures under HPDs. We report on an intervention employing the voluntary use of this technology in a worksite setting.Volunteers were fitted with a device allowing them to monitor noise exposure under their hearing protection on a daily basis. The trends in noise exposures for individuals who completed at least six months of the intervention were analysed.Recruitment occurred at three manufacturing facilities, with 127 workers enrolling and 66 workers actively using the device during their work shifts.Among volunteers downloading regularly, the percentage of daily exposures in excess of the OSHA action level (85 dBA) decreased from 14% to 8%, while the percentage of daily exposures in excess of 90 dBA decreased from 4% to less than 2%.Initial results from this longitudinal study indicate that volunteers find daily noise exposure monitoring to be feasible, and that workers who monitor daily are able to reduce exposures. The results of subject adherence shed light on the challenges and possibilities of worksite interventions for health and safety.
View details for DOI 10.3109/14992027.2012.743047
View details for Web of Science ID 000314532400002
View details for PubMedID 23373740
Further validation that claims data are a useful tool for epidemiologic research on hypertension
BMC PUBLIC HEALTH
The practice of using medical service claims in epidemiologic research on hypertension is becoming increasingly common, and several published studies have attempted to validate the diagnostic data contained therein. However, very few of those studies have had the benefit of using actual measured blood pressure as the gold standard. The goal of this study is to assess the validity of claims data in identifying hypertension cases and thereby clarify the benefits and limitations of using those data in studies of chronic disease etiology.Disease status was assigned to 19,150 employees at a U.S. manufacturing company where regular physical examinations are performed. We compared the presence of hypertension in the occupational medical charts against diagnoses obtained from administrative claims data.After adjusting for potential confounders, those with measured blood pressure indicating stage 1 hypertension were 3.69 times more likely to have a claim than normotensives (95% CI: 3.12, 4.38) and those indicating stage 2 hypertension were 7.70 times more likely to have a claim than normotensives (95% CI: 6.36, 9.35). Comparing measured blood pressure values identified in the medical charts to the algorithms for diagnosis of hypertension from the claims data yielded sensitivity values of 43-61% and specificity values of 86-94%.The medical service claims data were found to be highly specific, while sensitivity values varied by claims algorithm suggesting the possibility of under-ascertainment. Our analysis further demonstrates that such under-ascertainment is strongly skewed toward those cases that would be considered clinically borderline or mild.
View details for DOI 10.1186/1471-2458-13-51
View details for Web of Science ID 000314764800001
View details for PubMedID 23331960
Urinary Triclosan is Associated with Elevated Body Mass Index in NHANES.
2013; 8 (11)
Triclosan-a ubiquitous chemical in toothpastes, soaps, and household cleaning supplies-has the potential to alter both gut microbiota and endocrine function and thereby affect body weight.We investigated the relationship between triclosan and body mass index (BMI) using National Health and Nutrition Examination Surveys (NHANES) from 2003-2008. BMI and spot urinary triclosan levels were obtained from adults. Using two different exposure measures-either presence vs. absence or quartiles of triclosan-we assessed the association between triclosan and BMI. We also screened all NHANES serum and urine biomarkers to identify correlated factors that might confound observed associations.Compared with undetectable triclosan, a detectable level was associated with a 0.9-point increase in BMI (p<0.001). In analysis by quartile, compared to the lowest quartile, the 2nd, 3rd and 4th quartiles of urinary triclosan were associated with BMI increases of 1.5 (p<0.001), 1.0 (p = 0.002), and 0.3 (p = 0.33) respectively. The one strong correlate of triclosan identified in NHANES was its metabolite, 2,4-dichlorophenol (ρ = 0.4); its association with BMI, however, was weaker than that of triclosan. No other likely confounder was identified.Triclosan exposure is associated with increased BMI. Stronger effect at moderate than high levels suggests a complex mechanism of action.
View details for DOI 10.1371/journal.pone.0080057
View details for PubMedID 24278238
Job insecurity during recessions: effects on survivors' work stress.
BMC public health
2013; 13: 929-?
Previous studies show a variety of negative health consequences for the remaining workforce after downsizing events. This study examined self-reported work stress from 2009-2012 in the context of a large multi-site aluminum manufacturing company that underwent severe downsizing in 2009.This study examined the association between work stress and working at a work site that underwent severe downsizing. We assessed the level of downsizing across thirty plants in 2009 and categorized seven as having undergone severe downsizing. We linked plant-level downsizing information to individual workers' responses to an annual work engagement survey, which included three work stress questions. From 2009 to 2012 over 14, 000 employees were asked about their experience of work stress. Though the surveys were anonymous, the surveys captured employees' demographic and employment characteristic as well as plant location. We used hierarchical logistic regressions to compare responses of workers at severely downsized plants to workers at all other plant while controlling for demographic and plant characteristics. Responses to the work stress questions and one control question were examined.In all yearly surveys salaried workers consistently reported having more work stress than hourly workers. There was no differential in work stress for workers at severely downsized plants in 2009. In 2010 to 2012, salaried workers who remained at severely downsized plants reported significantly higher work stress than salaried workers at all other plants across multiple work stress questions. Examination of the 2006 survey confirmed that there were no pre-existing differences in work stress among salaried employees working at plants that would eventually experience severe downsizing. In addition, there was no difference in responses to the control question at severely downsized plants.Salaried workers at plants with high layoffs experienced more work stress after 2009 than their counterparts at non-high layoff plants. Increased work stress is important to monitor and may be a mediating pathway through which the external economic environment leads to adverse health outcomes.
View details for DOI 10.1186/1471-2458-13-929
View details for PubMedID 24093476
- How General Are Risk Preferences? Choices under Uncertainty in Different Domains AMERICAN ECONOMIC REVIEW 2012; 102 (6): 2606-2638
Cardiovascular diseases and Type 2 Diabetes in Bangladesh: A systematic review and meta-analysis of studies between 1995 and 2010
BMC PUBLIC HEALTH
Belief is that chronic disease prevalence is rising in Bangladesh since death from them has increased. We reviewed published cardiovascular (CVD) and Type 2 Diabetes Mellitus (T2DM) studies between 1995 and 2010 and conducted a meta-analysis of disease prevalence.A systematic search of CVD and T2DM studies yielded 29 eligible studies (outcome: CVD only = 12, T2DM only = 9, both = 8). Hypertension (HTN) was the primary outcome of CVD studies. HTN and T2DM were defined with objective measures and standard cut-off values. We assessed the study quality based on sampling frame, sample size, and disease evaluation. Random effects models calculated pooled disease prevalence (95% confidence interval) in studies with general population samples (n = 22).The pooled HTN and T2DM prevalence were 13.7% (12.1%-15.3%) and 6.7% (4.9%-8.6%), respectively. Both diseases exhibited a secular trend by 5-year intervals between 1995 and 2010 (HTN = 11.0%, 12.8%, 15.3%, T2DM = 3.8%, 5.3%, 9.0%). HTN was higher in females (M vs. F: 12.8% vs.16.1%) but T2DM was higher in males (M vs. F: 7.0% vs. 6.2%) (non-significant). Both HTN and T2DM were higher in urban areas (urban vs. rural: 22.2% vs. 14.3% and 10.2% vs. 5.1% respectively) (non-significant). HTN was higher among elderly and among working professionals. Both HTN and T2DM were higher in 'high- quality' studies.There is evidence of a rising secular trend of HTN and T2DM prevalence in Bangladesh. Future research should focus on the evolving root causes, incidence, and prognosis of HTN and T2DM.
View details for DOI 10.1186/1471-2458-12-434
View details for Web of Science ID 000311081700001
View details for PubMedID 22694854
Systematic evaluation of environmental factors: persistent pollutants and nutrients correlated with serum lipid levels
INTERNATIONAL JOURNAL OF EPIDEMIOLOGY
2012; 41 (3): 828-843
Both genetic and environmental factors contribute to triglyceride, low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein-cholesterol (HDL-C) levels. Although genome-wide association studies are currently testing the genetic factors systematically, testing and reporting one or a few factors at a time can lead to fragmented literature for environmental chemical factors. We screened for correlation between environmental factors and lipid levels, utilizing four independent surveys with information on 188 environmental factors from the Centers of Disease Control, National Health and Nutrition Examination Survey, collected between 1999 and 2006.We used linear regression to correlate each environmental chemical factor to triglycerides, LDL-C and HDL-C adjusting for age, age(2), sex, ethnicity, socio-economic status and body mass index. Final estimates were adjusted for waist circumference, diabetes status, blood pressure and survey. Multiple comparisons were controlled for by estimating the false discovery rate and significant findings were tentatively validated in an independent survey.We identified and validated 29, 9 and 17 environmental factors correlated with triglycerides, LDL-C and HDL-C levels, respectively. Findings include hydrocarbons and nicotine associated with lower HDL-C and vitamin E (?-tocopherol) associated with unfavourable lipid levels. Higher triglycerides and lower HDL-C were correlated with higher levels of fat-soluble contaminants (e.g. polychlorinated biphenyls and dibenzofurans). Nutrients and vitamin markers (e.g. vitamins B, D and carotenes), were associated with favourable triglyceride and HDL-C levels.Our systematic association study has enabled us to postulate about broad environmental correlation to lipid levels. Although subject to confounding and reverse causality bias, these findings merit evaluation in additional cohorts.
View details for DOI 10.1093/ije/dys003
View details for Web of Science ID 000306417300030
View details for PubMedID 22421054
Geographic and Racial Variation in Premature Mortality in the US: Analyzing the Disparities
2012; 7 (4)
Life expectancy at birth, estimated from United States period life tables, has been shown to vary systematically and widely by region and race. We use the same tables to estimate the probability of survival from birth to age 70 (S(70)), a measure of mortality more sensitive to disparities and more reliably calculated for small populations, to describe the variation and identify its sources in greater detail to assess the patterns of this variation. Examination of the unadjusted probability of S(70) for each US county with a sufficient population of whites and blacks reveals large geographic differences for each race-sex group. For example, white males born in the ten percent healthiest counties have a 77 percent probability of survival to age 70, but only a 61 percent chance if born in the ten percent least healthy counties. Similar geographical disparities face white women and blacks of each sex. Moreover, within each county, large differences in S(70) prevail between blacks and whites, on average 17 percentage points for men and 12 percentage points for women. In linear regressions for each race-sex group, nearly all of the geographic variation is accounted for by a common set of 22 socio-economic and environmental variables, selected for previously suspected impact on mortality; R(2) ranges from 0.86 for white males to 0.72 for black females. Analysis of black-white survival chances within each county reveals that the same variables account for most of the race gap in S(70) as well. When actual white male values for each explanatory variable are substituted for black in the black male prediction equation to assess the role explanatory variables play in the black-white survival difference, residual black-white differences at the county level shrink markedly to a mean of -2.4% (+/-2.4); for women the mean difference is -3.7% (+/-2.3).
View details for DOI 10.1371/journal.pone.0032930
View details for Web of Science ID 000305347400001
View details for PubMedID 22529892
Hearing effects from intermittent and continuous noise exposure in a study of Korean factory workers and firefighters
BMC PUBLIC HEALTH
South Korea and surrounding countries in East Asia are believed to have the highest proportion in the world of high frequency hearing loss due to occupational noise exposure, yet there has been limited information published in international journals, and limited information for control of noise in local workplaces beyond strategies from western countries. We exploit medical surveillance information from two worker groups to enhance local knowledge about noise-induced hearing loss and explore the possible importance of shift work to risk.Four-years of hearing data were evaluated for 81 male farm machine factory workers and 371 male firefighters who had successfully completed a health examination and questionnaires for the duration of the study period. The averages of hearing thresholds at 2, 3, and 4 kHz were used as the primary end-point for comparison. Repeat measure analysis adjusted for age, exposure duration and smoking status was used to measure the difference in hearing threshold between the two groups.Noise levels were measured in the factory at a mean of 82 dBA, with a range of 66-97. No concurrent measurements were taken for the firefighters, but historic comparison values showed a wider range but a similar mean of 76-79 dBA. Although losses during follow-up were negligible, the factory workers had significantly (P < 0.0001) more hearing loss at the baseline of the study than the firefighters in both ears at 2, 3, and 4 kHz, adjusted for age, duration of employment and smoking status. Among those with 10 years of employment, mean losses at these frequencies among the factory workers fell into the impairment range (> 25 dB loss). Firefighters also showed increased losses associated with longer exposure duration, but these were significantly less marked. Losses at lower frequencies (< or = 1 kHz) were negligible in both groups.Korean work environments with continuous noise exposure in the measured range should consider implementation of a hearing conservation program. Further evaluation of hearing loss in workers exposed to irregular or intermittent high noise levels, such as firefighters, is also warranted.
View details for DOI 10.1186/1471-2458-12-87
View details for Web of Science ID 000300291500001
View details for PubMedID 22284753
Genetic variability in molecular responses to chemical exposure.
2012; 101: 437-457
Individuals differ in their response to environmental exposures. In the following, we describe examples and paradigms of studying heritable differences in response to exposure-commonly known as "gene-environment interaction" or "ecogenetics"-and their relation to disease etiology and susceptibility. Our discussion is framed in three parts. In the first, we describe replicated examples of studies that have typified the field, single genetic variant, and exposure associations to disease. Second, we describe how studies have scaled up search for interaction using genome-wide measurement modalities, bioinformatics, and model organisms. Finally, we discuss a more comprehensive representation of chemical exposures as the "envirome" and how we may use the envirome to examine interplay between genetics and the environment.
View details for DOI 10.1007/978-3-7643-8340-4_15
View details for PubMedID 22945578
Effect of daily noise exposure monitoring on annual rates of hearing loss in industrial workers
OCCUPATIONAL AND ENVIRONMENTAL MEDICINE
2011; 68 (6): 414-418
Occupational noise-induced hearing loss (NIHL) is prevalent, yet evidence on the effectiveness of preventive interventions is lacking. The effectiveness of a new technology allowing workers to monitor daily at-ear noise exposure was analysed.Workers in the hearing conservation program of an aluminium smelter were recruited because of accelerated rates of hearing loss. The intervention consisted of daily monitoring of at-ear noise exposure and regular feedback on exposures from supervisors. The annual rate of change in high frequency hearing average at 2, 3 and 4 KHz before intervention (2000-2004) and 4 years after intervention (2006-2009) was determined. Annual rates of loss were compared between 78 intervention subjects and 234 controls in other company smelters matched for age, gender and high frequency hearing threshold level in 2005.Individuals monitoring daily noise exposure experienced on average no further worsening of high frequency hearing (average rate of hearing change at 2, 3 and 4 KHz = -0.5 dB/year). Matched controls also showed decelerating hearing loss, the difference in rates between the two groups being significant (p < 0.0001). Analysis of a subset of intervention subjects matched to controls for initial rate of hearing loss showed a similar trend but the difference was not statistically significant (p = 0.06).Monitoring daily occupational noise exposure inside hearing protection with ongoing administrative feedback apparently reduces the risk of occupational NIHL in industrial workers. Longer follow-up of these workers will help determine the significance of the intervention effect. Intervention studies for the prevention of NIHL need to include appropriate control groups.
View details for DOI 10.1136/oem.2010.055905
View details for Web of Science ID 000290516600007
View details for PubMedID 21193566
Aging, Transition, and Estimating the Global Burden of Disease
2011; 6 (5)
The World Health Organization's Global Burden of Disease (GBD) reports are an important tool for global health policy makers, however the accuracy of estimates for countries undergoing an epidemiologic transition is unclear. We attempted to validate the life table model used to generate estimates for all-cause mortality in developing countries.Data were obtained for males and females from the Human Mortality Database for all countries with available data every ten years from 1900 to 2000. These provided inputs for the GBD life table model and served as comparison observed data. Above age sixty model estimates of survival for both sexes differed substantially from those observed. Prior to the year 1960 for males and 1930 for females, estimated survival tended to be greater than observed; following 1960 for both males and females estimated survival tended to be less than observed. Viewing observed and estimated survival separately, observed survival past sixty increased over the years considered. For males, the increase was from a mean (sd) probability of 0.22 (0.06) to 0.46 (0.1). For females, the increase was from 0.26 (0.06) to 0.65 (0.08). By contrast, estimated survival past sixty decreased over the same period. Among males, estimated survival probability declined from 0.54 (0.2) to 0.09 (0.06). Among females, the decline was from 0.36 (0.12) to 0.15 (0.08).These results show that the GBD mortality model did not accurately estimate survival at older ages as developed countries transitioned in the twentieth century and may be similarly flawed in developing countries now undergoing transition. Estimates of the size of older-age populations and their attributable disease burden should be reconsidered.
View details for DOI 10.1371/journal.pone.0020264
View details for Web of Science ID 000291005800039
View details for PubMedID 21629652
Gender and sex differences in job status and hypertension
OCCUPATIONAL AND ENVIRONMENTAL MEDICINE
2011; 68 (1): 16-23
Studies have shown greater health risks associated with blue-collar manufacturing employment for women than men. It remains challenging, however, to distinguish gendered job status (affected by family composition and other personal characteristics) from sex-linked biological differences influencing physiological response to workplace physical hazards.We examined the effects of hourly (blue-collar) status on incident hypertension among men and women, using health claims data for 14, 618 white- and blue-collar aluminium manufacturing employees in eight US states. To explore gender differences in job status, we developed sex-stratified propensity score models identifying key socioeconomic predictors of hourly status for men and women. To examine the effects of hourly employment on hypertension risk, after adjusting for gender differences in job status, we applied time-weighted logistic regression models, stratified by propensity score, with additional adjustment for socioeconomic confounders.Family structure (partnership, parity) influenced job status for both sexes; single mothers were more likely to hold hourly jobs (OR 2.02; 95% CI 1.37 to 2.97) and partnered men with children less likely (OR 0.68; 95% CI 0.56 to 0.83). Education, age at hire and race influenced job status for both sexes. The effect of hourly status on hypertension was significant only among women predicted to be hourly (OR 1.78; 95% CI 1.34 to 2.35).Our results indicate significant risks of hypertension associated with hourly status for women, possibly exacerbated by sociodemographic factors predicting hourly status (eg, single parenthood, low education). Greater attention to gender differences in job status, and finer exploration of sex-linked biological differences influencing responsivity to workplace exposures, is warranted.
View details for DOI 10.1136/oem.2009.049908
View details for Web of Science ID 000285182900005
View details for PubMedID 20864467
Prevalence of beryllium sensitization among aluminium smelter workers
2010; 60 (7): 569-571
Beryllium exposure occurs in aluminium smelters from natural contamination of bauxite, the principal source of aluminium.To characterize beryllium exposure in aluminium smelters and determine the prevalence rate of beryllium sensitization (BeS) among aluminium smelter workers.A population of 3185 workers from nine aluminium smelters owned by four different aluminium-producing companies were determined to have significant beryllium exposure. Of these, 1932 workers participated in medical surveillance programmes that included the serum beryllium lymphocyte proliferation test (BeLPT), confirmation of sensitization by at least two abnormal BeLPT test results and further evaluation for chronic beryllium disease in workers with BeS.Personal beryllium samples obtained from the nine aluminium smelters showed a range of <0.01-13.00 ?g/m(3) time-weighted average with an arithmetic mean of 0.25 ?g/m(3) and geometric mean of 0.06 ?g/m(3). Nine workers were diagnosed with BeS (prevalence rate of 0.47%, 95% confidence interval = 0.21-0.88%).BeS can occur in aluminium smelter workers through natural beryllium contamination of the bauxite and further concentration during the refining and smelting processes. Exposure levels to beryllium observed in aluminium smelters are similar to those seen in other industries that utilize beryllium. However, compared with beryllium-exposed workers in other industries, the rate of BeS among aluminium smelter workers appears lower. This lower observed rate may be related to a more soluble form of beryllium found in the aluminium smelting work environment as well as the consistent use of respiratory protection.
View details for DOI 10.1093/occmed/kqq097
View details for Web of Science ID 000282329000013
View details for PubMedID 20610489
ESTIMATING WELFARE IN INSURANCE MARKETS USING VARIATION IN PRICES
QUARTERLY JOURNAL OF ECONOMICS
2010; 125 (3): 877-921
We provide a graphical illustration of how standard consumer and producer theory can be used to quantify the welfare loss associated with inefficient pricing in insurance markets with selection. We then show how this welfare loss can be estimated empirically using identifying variation in the price of insurance. Such variation, together with quantity data, allows us to estimate the demand for insurance. The same variation, together with cost data, allows us to estimate how insurer's costs vary as market participants endogenously respond to price. The slope of this estimated cost curve provides a direct test for both the existence and nature of selection, and the combination of demand and cost curves can be used to estimate welfare. We illustrate our approach by applying it to data on employer-provided health insurance from one specific company. We detect adverse selection but estimate that the quantitative welfare implications associated with inefficient pricing in our particular application are small, in both absolute and relative terms.
View details for Web of Science ID 000281353500001
View details for PubMedID 21218182
Childhood Lead Exposure After the Phaseout of Leaded Gasoline: An Ecological Study of School-Age Children in Kampala, Uganda
ENVIRONMENTAL HEALTH PERSPECTIVES
2010; 118 (6): 884-889
Tetraethyl lead was phased out of gasoline in Uganda in 2005. Recent mitigation of an important source of lead exposure suggests examination and re-evaluation of the prevalence of childhood lead poisoning in this country. Ongoing concerns persist about exposure from the Kiteezi landfill in Kampala, the country's capital.We determined blood lead distributions among Kampala schoolchildren and identified risk factors for elevated blood lead levels (EBLLs; >or= 10 microg/dL). Analytical approach: Using a stratified, cross-sectional design, we obtained blood samples, questionnaire data, and soil and dust samples from the homes and schools of 163 4- to 8-year-old children representing communities with different risks of exposure.The mean blood lead level (BLL) was 7.15 microg/dL; 20.5% of the children were found to have EBLL. Multivariable analysis found participants whose families owned fewer household items, ate canned food, or used the community water supply as their primary water source to have higher BLLs and likelihood of EBLLs. Distance < 0.5 mi from the landfill was the factor most strongly associated with increments in BLL (5.51 microg/dL, p < 0.0001) and likelihood of EBLL (OR = 4.71, p = 0.0093). Dust/soil lead was not significantly predictive of BLL/EBLL.Lead poisoning remains highly prevalent among school-age children in Kampala. Confirmatory studies are needed, but further efforts are indicated to limit lead exposure from the landfill, whether through water contamination or through another mechanism. Although African nations are to be lauded for the removal of lead from gasoline, this study serves as a reminder that other sources of exposure to this potent neurotoxicant merit ongoing attention.
View details for DOI 10.1289/ehp.0901768
View details for Web of Science ID 000278591300036
View details for PubMedID 20194080
- Effects of Externally Rated Job Demand and Control on Depression Diagnosis Claims in an Industrial Cohort AMERICAN JOURNAL OF EPIDEMIOLOGY 2010; 171 (3): 303-311
Reproductive Outcomes Among Male and Female Workers at an Aluminum Smelter
JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL MEDICINE
2010; 52 (2): 137-143
Several adverse pregnancy outcomes were reported among female laboratory workers in a North American aluminum smelter. To determine whether these outcomes were associated with any occupational exposure at the plant, a cross-sectional survey was undertaken.Rates of miscarriage, premature singleton birth, and major congenital anomaly occurring during employment were compared with a reference group comprised of all pregnancies that occurred before employment.Among female workers, the excess of congenital anomalies among female laboratory workers that defined the initial cluster was observed, but no specific pattern was found.On the basis of these analyses, the increase in congenital anomalies could not be attributed to occupational exposures at the smelter nor could potential exposure likely explain the diverse anomalies described.
View details for DOI 10.1097/JOM.0b013e3181cb59bc
View details for Web of Science ID 000274491600004
View details for PubMedID 20134342
Long-term follow-up of beryllium sensitized workers from a single employer
BMC PUBLIC HEALTH
Up to 12% of beryllium-exposed American workers would test positive on beryllium lymphocyte proliferation test (BeLPT) screening, but the implications of sensitization remain uncertain.Seventy two current and former employees of a beryllium manufacturer, including 22 with pathologic changes of chronic beryllium disease (CBD), and 50 without, with a confirmed positive test were followed-up for 7.4 +/-3.1 years.Beyond predicted effects of aging, flow rates and lung volumes changed little from baseline, while DLCO dropped 17.4% of predicted on average. Despite this group decline, only 8 subjects (11.1%) demonstrated physiologic or radiologic abnormalities typical of CBD. Other than baseline status, no clinical or laboratory feature distinguished those who clinically manifested CBD at follow-up from those who did not.The clinical outlook remains favorable for beryllium-sensitized individuals over the first 5-12 years. However, declines in DLCO may presage further and more serious clinical manifestations in the future. These conclusions are tempered by the possibility of selection bias and other study limitations.
View details for DOI 10.1186/1471-2458-10-5
View details for Web of Science ID 000274831600003
View details for PubMedID 20047684
Work and its role in shaping the social gradient in health
BIOLOGY OF DISADVANTAGE: SOCIOECONOMIC STATUS AND HEALTH
2010; 1186: 102-124
Adults with better jobs enjoy better health: job title was, in fact, the social gradient metric first used to study the relationship between social class and chronic disease etiology, a core finding now replicated in most developed countries. What has been less well proved is whether this correlation is causal, and if so, through what mechanisms. During the past decade, much research has been directed at these issues. Best evidence in 2009 suggests that occupation does affect health. Most recent research on the relationship has been directed at disentangling the pathways through which lower-status work leads to adverse health outcomes. This review focuses on six areas of recent progress: (1) the role of status in a hierarchical occupational system; (2) the roles of psychosocial job stressors; (3) effects of workplace physical and chemical hazard exposures; (4) evidence that work organization matters as a contextual factor; (5) implications for the gradient of new forms of nonstandard or "precarious" employment such as contract and shift work; and (6) emerging evidence that women may be impacted differently by adverse working conditions, and possibly more strongly, than men.
View details for DOI 10.1111/j.1749-6632.2009.05338.x
View details for Web of Science ID 000277908000007
View details for PubMedID 20201870
- Heart disease & the workplace INDIAN JOURNAL OF MEDICAL RESEARCH 2009; 130 (4): 351-353
Invited Commentary: The Search for Preventable Causes of Cardiovascular Disease-Whither Work?
AMERICAN JOURNAL OF EPIDEMIOLOGY
2009; 169 (12): 1422-1425
The incidence and mortality of the major cardiovascular disorders vary sharply by occupation, but this is usually attributed to broad socioeconomic factors; the contributions of physical and psychosocial stressors at work remain obscure or controversial. Review of the ongoing studies of cardiovascular disease in the United States in this issue of the Journal demonstrates that few have either collected sufficient occupational data or used these data in published analyses to address this issue. There are compelling reasons to study this issue, starting with the sheer magnitude of the occupational gradient and disease prevalence. If only 5%-15% prove causally linked to preventable factors, an enormous disease-control opportunity would present itself. Moreover, the most suspect work factors-job stress, fine particulate dust, heat, noise, and shiftwork-are highly prevalent in the US workforce. Thankfully, there is evidence that many of the large ongoing studies are moving toward enhancing their occupational data and using what they have already collected. However, because of the complexity of studying these relations, the better solution is not retrofitting but designing studies in the future that combine de novo the conceptual frameworks and technical skills of occupational and social epidemiologists with those of more biologically focused investigators.
View details for DOI 10.1093/aje/kwp078
View details for Web of Science ID 000266953700002
View details for PubMedID 19429877
Healthcare for Obstructive Lung Disease in an Industrial Spirometry Surveillance Program
JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL MEDICINE
2009; 51 (3): 336-342
The efficacy of workplace spirometry surveillance programs is unclear. We examine whether aluminum industry workers with airflow obstruction (AO) received health care for obstructive lung disease.We performed a cross sectional analysis over 7 years of 6821 aluminum production workers. The primary outcome was the association between obstructive lung disease insurance claims and the presence of AO. We also examined whether the presence of claims was associated with increasing AO severity.Although workers with AO more frequently had claims, 60% of workers with AO, most frequently those with mild and borderline obstruction, had no claim.Workers with AO, particularly borderline and mild obstruction, frequently do not receive health care despite respiratory surveillance. Further investigation is needed to determine if workers with undiagnosed AO are symptomatic or have accelerated losses in lung function over time.
View details for DOI 10.1097/JOM.0b013e3181954ae6
View details for Web of Science ID 000264140300007
View details for PubMedID 19225419
- MARKETWATCH Who Chooses A Consumer-Directed Health Plan? HEALTH AFFAIRS 2008; 27 (6): 1671-1679
Organic solvent exposure and hearing loss in a cohort of aluminium workers
OCCUPATIONAL AND ENVIRONMENTAL MEDICINE
2008; 65 (4): 230-235
Organic solvent exposure has been shown to cause hearing loss in animals and humans. Less is known about the risk of hearing loss due to solvent exposures typically found in US industry. The authors performed a retrospective cohort study to examine the relationship between solvent exposure and hearing loss in US aluminium industry workers.A cohort of 1319 workers aged 35 years or less at inception was followed for 5 years. Linkage of employment, industrial hygiene and audiometric surveillance records allowed for estimation of noise and solvent exposures and hearing loss rates over the study period. Study subjects were classified as "solvent exposed" or not, on the basis of industrial hygiene records linked with individual job histories. High frequency hearing loss was modelled as both a continuous and a dichotomous outcome.Typical solvent exposures involved mixtures of xylene, toluene and/or methyl ethyl ketone (MEK). Recorded solvent exposure levels varied widely both within and between jobs. In a multivariate logistic model, risk factors for high frequency hearing loss included age (OR = 1.06, p = 0.004), hunting or shooting (OR = 1.35, p = 0.049), noisy hobbies (OR = 1.74, p = 0.01), baseline hearing level (OR = 1.04, p<0.001) and solvent exposure (OR = 1.87, p = 0.004). A multivariate linear regression analysis similarly found significant associations between high frequency hearing loss and age (p<0.001), hunting or shooting (p<0.001), noisy hobbies (p = 0.03), solvent exposure (p<0.001) and baseline hearing (p = 0.03).These results suggest that occupational exposure to organic solvent mixtures is a risk factor for high frequency hearing loss, although the data do not allow conclusions about dose-response relationships. Industries with solvent-exposed workers should include such workers in hearing conservation programs.
View details for DOI 10.1136/oem.2006.031047
View details for Web of Science ID 000254121000005
View details for PubMedID 17567727
Beryllium sensitization in aluminum smelter workers
JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL MEDICINE
2008; 50 (2): 157-162
To determine whether beryllium-related disease exists among aluminum smelter workers.A total of 1278 employees from four aluminum smelters determined to have significant beryllium exposure based on 5 years of sampling were invited to participate in medical surveillance that included a respiratory symptoms questionnaire, spirometry, and blood beryllium lymphocyte proliferation test.Of these, 734 employees participated in the program. Beryllium exposure from 965 personal samples ranged from 0.002 to 13.00 microg/m time-weighted average, with a median of 0.05 microg/m, geometric mean of 0.05 microg/m, and arithmetic mean of 0.22 microg/m. Only two employees had confirmed beryllium sensitization (0.27%).There is evidence of beryllium sensitization among aluminum smelter workers. When compared with beryllium-exposed workers in other industries, aluminum smelter workers had lower rates of sensitization. The low beryllium sensitization rate observed may be related to work practices and the properties of the beryllium found in this work environment.
View details for DOI 10.1097/JOM.0b013e318161783f
View details for Web of Science ID 000253217100008
View details for PubMedID 18301172