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Biomedical subjects

David H Wegman

Publications and source records attributed to David H Wegman.

At least 19 recordsLinked to original sources
PubMed2006

The social distribution of risk at work: acute injuries and physical assaults among healthcare workers working in a long-term care facility.

The roles of informal social ties in affecting healthcare workers' risk of injury and assault were investigated in a long-term care facility for the elderly in the US. The original hypothesis was that nurses and healthcare assistants who integrated more with their coworkers would have lower risk. A crude measure of familiarity and social integration with coworkers was constructed from staff attendance records. This variable, which indicates working a floor and shift one has routinely worked on in the past, was associated with a moderate increase in risk of being injured after controlling for lifting demands and a fairly strong increased risk of being assaulted after controlling for resident combativeness. An interaction between social integration and job title was found. The primary associations were in the opposite direction of what was expected. The results suggest that social forces among healthcare workers shape the distribution of risk among workers in a manner more complex than some theories of social integration have suggested. New hypotheses are proposed to explore how social norms and expectations affect the way workers interact with each other and shape the distribution of risk among workgroup members.

Adult↗
PubMed2006

Risk factors for recruit exertional heat illness by gender and training period.

INTRODUCTION: Exertional heat illness (EHI) is a recurrent problem for both male and female recruits during basic military training. A matched case control study investigated the effects of fitness and conditioning on EHI risk among Marine Corps recruits during 12 wk of basic training at Marine Corps Recruit Depot, Parris Island, SC. METHODS: Physical fitness and anthropometric measurements at entrance were acquired for 627 EHI cases that occurred during the period 1988-1996 and for 1802 controls drawn from the same training platoons. Conditional logistic regression was used to estimate EHI risk. RESULTS: Slower physical fitness test run times during processing week strongly predicted risk for subsequent EHI in both male and female recruits. A 9% increase in risk for EHI associated with body mass index (BMI = kg x m(-2); weight/height2) was found in male recruits, while BMI was not associated with risk among female recruits. BMI and initial run time were important predictors for EHI in early training, while in late training the initial BMI was no longer as important a risk factor and improvements in fitness reduced risk. CONCLUSION: Tables of estimated absolute risks categorized by BMI and VO2max are provided as a guide for identifying recruits who are at high risk for developing EHI during training.

Adult↗
PubMed2005

Work and behavioural problems in children and adolescents.

METHODS: We conducted a cross-sectional study of 3139 children and adolescents from poor areas of the city of Pelotas, southern Brazil. We employed the child behaviour checklist for estimating BP. We performed multivariable analysis using Poisson's regression for confounder control. RESULTS: The proportion of workers was 13.8% (7.3% among children and 20.7% among adolescents). Prevalence of BP among workers and prevalence ratios (PRs) were 21.4% (PR = 1.3; CI 0.9-1.9) among children and 9.5% (PR = 0.6; CI 0.4-1.0) among adolescents. Considering workers only, the risk of BP was 2.7 times greater (CI 1.4-5.1) among children when compared with adolescents. Working in domestic services among children and beginning to work at an early age among adolescents were associated with BP. CONCLUSIONS: Our results reinforce the need for respecting the minimum age for admission to employment established by the ILO Convention 138 and by the Brazilian legislation and contribute to the discussion about the occupations that should be considered as hazardous child labour.

Adolescent↗
PubMed2005

Occupational exposure to metalworking fluids and risk of breast cancer among female autoworkers.

BACKGROUND: Metalworking fluids (MWF) are used for lubrication during metal manufacturing. Previous studies have observed increased risks of several cancers among MWF-exposed workers. We hypothesized that MWF may be associated with risk of breast cancer because they can contain carcinogenic or endocrine-disrupting chemicals. METHODS: We conducted a case-control study nested in a cohort of 4,680 female automobile workers employed for at least 3 years between 1/1/41 and 1/1/85, with follow-up through 1994. Cases were identified using the National Death Index (NDI), Michigan cancer registries, and company records. Detailed quantitative MWF exposure data were available for each subject, although data on known breast cancer risk factors were not. RESULTS: Ninety-nine cases of breast cancer and 626 matched controls were identified. There was a weak positive association between lifetime cumulative exposure to soluble MWF and breast cancer risk, but no evidence of association with either straight or synthetic fluids. When exposure was divided into time-windows, the association was strongest for soluble MWF in the decade preceding diagnosis. Controlling for earlier exposures, there was an odds ratio of 1.18 (95% CI=1.02-1.35) per mg/m3-year of cumulative exposure to soluble MWF in this 10-year period. CONCLUSION: This hypothesis-generating study provides some preliminary evidence for an association between exposure to soluble MWF and increased risk of breast cancer. Additional studies of MWF and breast cancer, with data on known breast cancer risk factors, are warranted.

Adult↗
PubMed2005

Risk of breast cancer among enlisted Army women occupationally exposed to volatile organic compounds.

BACKGROUND: The military presents a unique opportunity to study the incidence of disease in a population with complete knowledge of person-time and occupation. Women in the Army are employed more frequently in non-traditional, industrial jobs such as auto mechanic and motor transport operators than in the general US population, increasing the probability of exposure to industrial chemicals. A cohort to investigate the risk of breast cancer among active duty Army women occupationally exposed to volatile organic chemicals (VOCs) was constructed. METHODS: Age-adjusted incidence rates for breast cancer were calculated for more than 270,000 enlisted women who served between 1980-1996. Twenty-one VOCs, described in previously published literature as having a potential risk of breast cancer, were identified in an Army industrial hygiene survey database. Job title histories were linked to workplace chemical evaluations conducted by Army industrial hygienists, which included a subjective exposure potential rating (high, medium, low, and none) for each VOC. Poisson regression analysis was used to evaluate the association between the exposure rating by job title and breast cancer. RESULTS: The incidence of breast cancer in the cohort was significantly elevated in women younger than 35 years of age, especially among black women, when compared to the age-specific rates in the general population. Women who worked in occupations with a moderate to high exposure potential to at least one VOC had a 48% increased risk (P < 0.05) of breast cancer while on active duty between 1980-1996 when compared to those women with low to no exposure potential. CONCLUSIONS: This study provides preliminary evidence that exposure to one or more of the study VOCs is associated with an increased risk of breast cancer. Further substance-specific, quantitative analyses are warranted.

Adult↗
PubMed2005

A biological approach to characterizing exposure to metalworking fluids and risk of prostate cancer (United States).

OBJECTIVE: Prostate cancer is hormone-related and chemicals that interfere with hormones may contribute to carcinogenesis. In a cohort of autoworkers we characterized exposure to metalworking fluids (MWF) into age windows with homogenous biological risk for prostate cancer, and examined exposure-response relationships using semi-parametric modeling. METHODS: Incident cases (n=872) were identified via Michigan cancer registry from 1985 through 2000. Controls were selected using incidence-density sampling, 5:1 ratio. Using a hormonal-based model, exposure was accumulated in three windows: (1) late puberty, (2) adulthood, and (3) middle age. We used penalized splines to model risk as a smooth function of exposure, and controlled for race and calendar year of diagnosis in a Cox model. RESULTS: Risk of prostate cancer linearly increased with exposure to straight MWF in the first window, with a relative risk of 2.4 per 10 mg/m(3)-years. Autoworkers exposed to MWF at a young age also had an increased risk associated with MWF exposure incurred later in life. For soluble MWF there was a slightly increased risk in the third window. CONCLUSIONS: Exposure characterization based on a hormonal model identified heightened risk with early age of exposure to straight MWF. Results also support a long latency period for exposure related prostate cancer.

Adolescent↗
PubMed2005

Determinants of airborne fiber size in the glass fiber production industry.

Size distributions of airborne fiber exposures should be characterized for studies of respiratory disease because size determines the region of the lung where a fiber will deposit and its ability to produce toxic effects in cells. Yet fiber size is not measured precisely with standard air sampling methods. Specific fiber dimensions hypothesized to have biologic activity have been proposed, but these have not been evaluated in epidemiologic studies because there has not been a way to account for fiber size in historical air monitoring data. In this study, methods were developed to predict fibrous aerosol size fractions generated during glass wool fiber production using regression models and factors related to bulk fiber products and processing. A set of air samples representing a range of products and process applications was collected in eight fiber glass production facilities. The samples were analyzed more intensively than standard methods require. For each air sample, total fiber size distributions were measured using electron microscopy and two proportions were then calculated: (1) fibers meeting the size criteria of the standard NIOSH Method 7400 B rules method (pB), and (2) fibers meeting the size criteria for a biologically based exposure index, the hypothetically active fiber (HAF1) index (pH1). The fiber size proportions were used as dependent variables in regression models with production process factors. It was found that two factors, the nominal diameter of the bulk fiber product and whether oil was applied to it, determine more than 80% of the variability in the proportions (for the pB model, R2 = 0.86; for the pH1 model, R2 = 0.82). Using these two predicted proportions, it is possible to estimate the concentration of fibers in the biologically based HAF1 size fraction from a standard fiber concentration measurement. The models developed here can be used to size-adjust historical fiber concentration measurements for use in epidemiologic studies of respiratory disease.

Air Pollution, Indoor↗
PubMed2005

Prevalence of musculoskeletal disorders in union ironworkers.

The prevalence of musculoskeletal disorder (MSD) symptoms and doctor-diagnosed musculoskeletal disorders (DDMDs) were estimated among union construction ironworkers by a telephone-administered questionnaire. Of 1996 ironworkers eligible, 1566 were contacted and 981 were interviewed. The prevalence of self-reported MSD symptoms was high for the lower back (56%), wrist/hands/fingers (40%), knees (39%), and shoulders (36%). The most common DDMDs were tendonitis (19%), ruptured disk in the back (18%), bursitis in the shoulder (15%), and carpal tunnel syndrome (12%). Generally, the prevalence of DDMDs and MSD symptoms increased with duration of employment. In age-adjusted logistic regression analyses, those who worked 25 to 35 years were more likely to have tendonitis (odds ratio [OR] 7.1, 95% confidence interval [CI] 3.116.6), shoulder bursitis (OR 13.7, 95% CI 3.160.4), knee bursitis (OR 5.1, 95% CI 1.025.1), and ruptured intervertebral back disk (OR 6.7, 95% CI 2.617.5). The effect of prior injury was also consistently high (upper extremities, OR 4.6; lower extremities OR 5.1; lower back, OR 6.0). Among workers without prior injuries, MSD symptoms were more frequent for the lower back in structural ironwork (OR 1.7, 95% CI 1.12.6), and for the upper extremity in concrete reinforcement ironwork (OR 1.9, 95% CI 1.22.9). These findings suggest that some musculoskeletal morbidity in construction ironworkers may be work related and thus preventable.

Adult↗
PubMed2005

Prostate cancer incidence in relation to time windows of exposure to metalworking fluids in the auto industry.

BACKGROUND: Exposure to metalworking fluids has been previously associated with prostate cancer mortality in a cohort of autoworkers. Our objective was to further explore this finding in a study of prostate cancer incidence in the same cohort, with reduced misclassification of outcome. METHODS: We conducted a nested case-control study in the General Motors cohort of autoworkers. Incident cases of prostate cancer (n = 872) were identified via the Michigan Cancer Registry from 1985 through 2000. Controls were selected using incidence-density sampling with 5:1 ratio. Using cumulative exposure (mg/m-years) as the dose metric, we first examined varying lengths of lags (0-25 years). Then, we evaluated consecutive windows of exposure: 25 or more years before risk age, and fewer than 25 years. We used penalized splines to model the relative risk as a smooth function of exposure, and adjusted for race and calendar year of diagnosis in a Cox model. RESULTS: Risk of prostate cancer increased with exposure to soluble and straight fluids 25 years or more before risk age but not with exposure in the last 25 years. The relationship with soluble fluids was piecewise linear, with a small increase in risk at lower exposures followed by a steeper rise. By contrast, the relationship with straight fluids was linear, with a relative risk of 1.12 per 10mg/m-years of exposure (95% confidence interval = 1.04-1.20). CONCLUSIONS: Exposure to oil-based fluids, soluble and straight, is modestly associated with prostate cancer risk among autoworkers, with a latency period of at least 25 years.

Adult↗
PubMed2005

The effects of continuous hot weather training on risk of exertional heat illness.

PURPOSE: To determine whether cumulative daily average wet-bulb globe temperature (WBGT) index, over one or two preceding days, is a better measure for predicting cases of exertional heat illness (EHI) than current daily average WBGT, which is the standard heat index used by the Marine Corps; and to identify the most accurate index of heat stress to prevent and predict future cases of EHI. METHODS: A case-crossover study was conducted in male and female Marine Corps recruits in basic training at Marine Corps Recruit Depot, Parris Island, SC. Weather measurements were obtained for 2069 cases of EHI during 1979-1997 and for randomly selected control periods before and after each EHI episode. RESULTS: The risk of EHI increased with WBGT (OR = 1.11 degrees F(-1); 95% CI, 1.10-1.13). EHI risk was associated not only with the WBGT at the time of the event (OR = 1.10 degrees F(-1); 95% CI, 1.08-1.11) but with the previous day's average WBGT as well (OR = 1.03 degrees F(-1); 95% CI, 1.02-1.05). Alternative combinations of WBGT components were identified that better predicted EHI risk. CONCLUSION: Our results provide evidence for a cumulative effect of previous day's heat exposure on EHI risk in these Marine Corps recruits. A simple index for use in predicting EHI risk is proposed that includes the dry-bulb temperature and the relative humidity.

Adult↗
PubMed2005

Registry-based case-control studies of liver cancer and cancers of the biliary tract nested in a cohort of autoworkers exposed to metalworking fluids.

OBJECTIVE: Results are presented for a registry-based study of hepatobiliary cancer (liver and biliary tract) nested in a cohort of workers from three automobile manufacturing plants with potential exposure to metalworking fluids. METHODS: Altogether 63 cases of hepatobiliary cancer were identified from the cohort by the Michigan cancer registries. Each case was matched to 10 controls. Odds ratios (OR) were estimated in conditional logistic regression models for lifetime exposure to straight, soluble, and synthetic metalworking fluid and fluid components. RESULTS: Overall, hepatobiliary cancer was not associated with exposure to metalworking fluids. However, when the cases were stratified into liver cancer (N = 39) and biliary tract cancer (N = 24) the risk was nonhomogeneous across the two categories. While liver cancer was not associated with exposure to metalworking fluids, the results suggested a possible excess risk of biliary tract cancer with more than 1.0 mg/m3-years of exposure to straight metalworking fluids [OR 2.7, 95% confidence interval (95% CI) 0.9-7.6], as well as any exposure to chlorinated paraffins (OR 3.9, 95% CI 0.9-17). When exposures to straight metalworking fluids were separated into 10-year exposure periods, the odds ratio increased to 6.24 (95% CI 1.62-24.16) for exposures occurring > 20 years prior to the risk date. CONCLUSIONS: There is limited evidence that exposure to straight metalworking fluids is associated with biliary tract cancer. The small numbers of cases of these rare cancers were reflected in the wide confidence intervals, and these findings need to be examined further in other exposed populations.

Adult↗
PubMed2004

Quantitative evaluation of the effects of uncontrolled confounding by alcohol and tobacco in occupational cancer studies.

BACKGROUND: Uncontrolled confounding by personal exposures like smoking can limit the inferential power of occupational cohort studies. We developed and demonstrate a refinement of an existing type of sensitivity analysis, indirect adjustment, for evaluating the potential magnitude of confounding by alcohol and tobacco. Results of a large retrospective cohort study of laryngeal cancer and exposure to metalworking fluids (MWF) are used to illustrate the methods. METHODS: Data on smoking and drinking habits representative of the study cohort were obtained from a sample of US manufacturing workers from the 1977 National Health Interview Survey (NHIS). Two different mechanisms were assumed to affect the distribution of confounding factors between MWF exposure groups: socially determined and chance differences. Chance variation was investigated with Monte Carlo sampling from the NHIS survey distribution of smoking and drinking. An upper bound on systematic differences in smoking and drinking was set by assuming that differences between exposure groups within the same unionized blue collar workforce were very unlikely to be larger than differences between blue and white collar manufacturing workers in the NHIS data. RESULTS: Under plausibly large differences in smoking and drinking habits among MWF exposure groups occurring by either mechanism, the exposure-risk association was unlikely to have been over- or under-estimated by as much as 20%. CONCLUSIONS: When comparing exposure groups within the same working population, it is unlikely that either systematic or chance differences in smoking and drinking habits will cause as much as a 20% change in the relative risk in large studies. While this study focused on an occupational exposure and laryngeal cancer, there are many situations in which epidemiologists are concerned that unmeasured 'lifestyle factors' may differ among exposure groups, and it would appear that the likely confounding effect of such differences will often be modest.

Adult↗
PubMed2004

Work-related musculoskeletal disorders: the epidemiologic evidence and the debate.

The debate about work-relatedness of musculoskeletal disorders (MSDs) reflects both confusion about epidemiologic principles and gaps in the scientific literature. The physical ergonomic features of work frequently cited as risk factors for MSDs include rapid work pace and repetitive motion, forceful exertions, non-neutral body postures, and vibration. However, some still dispute the importance of these factors, especially relative to non-occupational causes. This paper addresses the controversy with reference to a major report recently commissioned by the US Congress from the National Research Council (NRC) and Institute of Medicine (IOM) (2001). The available epidemiologic evidence is substantial, but will benefit from more longitudinal data to better evaluate gaps in knowledge concerning latency of effect, natural history, prognosis, and potential for selection bias in the form of the healthy worker effect. While objective measures may be especially useful in establishing a more secure diagnosis, subjective measures better capture patient impact. Examination techniques still do not exist that can serve as a "gold standard" for many of the symptoms that are commonly reported in workplace studies. Finally, exposure assessment has too often been limited to crude indicators, such as job title. Worker self-report, investigator observation, and direct measurement each add to understanding but the lack of standardized exposure metrics limits ability to compare findings among studies. Despite these challenges, the epidemiologic literature on work-related MSDs-in combination with extensive laboratory evidence of pathomechanisms related to work stressors-is convincing to most. The NRC/IOM report concluded, and other reviewers internationally have concurred, that the etiologic importance of occupational ergonomic stressors for the occurrence of MSDs of the low back and upper extremities has been demonstrated.

Ergonomics↗
PubMed2004

Is chronic airway obstruction from cotton dust exposure reversible?

BACKGROUND: Exposure to cotton dust is known to cause chronic airway obstruction, but there is little information on whether the obstructive impairment is reversible after the exposure stops. METHODS: Longitudinal changes in lung function were evaluated among 429 cotton textile workers and 449 silk workers in Shanghai, China, beginning in 1981. Both active and retired workers were tested every 4 to 6 years for 15 years. RESULTS: Overall, cotton workers had greater annual declines in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC). Compared with active workers, retired cotton workers had lower annual loss of FEV1, although the retired workers had a greater loss during their active employment than the currently active workers. No such trends were detected in silk workers. Annual declines in FEV1 in retired cotton workers were smaller with increasing time since retirement. Multivariate analysis showed that retirement was a substantial contributing factor for improved FEV1 and FVC in the cotton workers, especially among those who did not smoke. Correspondingly, remission of airflow obstruction, defined as a ratio of FEV1 and FVC of less than 70%, was more common in retirees than in the active workers, and more common in nonsmokers than in smokers. CONCLUSION: Chronic airway obstruction related to long-term exposure to cotton dust may be partially reversible after the exposure ceases, although lung function does not return to the level found in unexposed workers.

Adult↗
PubMed2004

Wounding the messenger: the new economy makes occupational health indicators too good to be true.

The U.S. Bureau of Labor Statistics and workers' compensation insurers reported dramatic drops in rates of occupational injuries and illnesses during the 1990s. The authors argue that far-reaching changes in the 1980s and 1990s, including the rise of precarious employment, falling wages and opportunities, and the creation of a super-vulnerable population of immigrant workers, probably helped create this apparent trend by preventing employees from reporting some injuries and illnesses. Changes in the health care system, including loss of access to health care for growing numbers of workers and increased obstacles to the use of workers' compensation, compounded these effects by preventing the diagnosis and documentation of some occupational injuries and illnesses. Researchers should examine these forces more closely to better understand trends in occupational health.

Data Collection↗
PubMed2003

Role of underlying pulmonary obstruction in short-term airway response to metal working fluid exposure: a reanalysis.

BACKGROUND: Among epidemiologic studies that found evidence for associations between exposures to metal working fluids (MWF) and pulmonary function impairments, one found effects restricted to workers with fixed obstruction at baseline. We reanalyzed a previously published study on MWF exposure and cross-shift pulmonary function to further evaluate this finding. METHODS: Pulmonary function was measured cross-shift on Monday and Friday in 131 male automotive workers. Quantitative personal MWF exposure data were available. Those with an FEV(1)/FVC ratio of <or=0.72 were considered obstructed. RESULTS: There was a trend towards increasing incidence of cross-shift decrement in FEV(1) as MWF exposure increased in the full cohort as well as when the results were restricted to the 19 (14.5%) who were obstructed. Those with obstruction were slightly more likely to show decrements in FEV(1) on Fridays. Removing the obstructed subgroup did not appear to substantially weaken the exposure-response relation. CONCLUSIONS: No important differences were found in cross-shift effects of MWF between obstructed and non-obstructed workers.

Adult↗
PubMed2003

Truncating the dose range for methacholine challenge tests: three occupational studies.

The methacholine challenge test protocol was assessed in the reanalysis of three occupational studies. We evaluated the impact of truncating the range of methacholine on responsiveness, as defined by slope and PC(20). In original analysis, reactivity was similar for apprentices and auto body shop workers, whereas boilermakers were more responsive. Truncating high concentrations did not change the classification of subjects with PC(20) <8 or 16 in any population. However, when responsiveness was measured by slope, the mean responsiveness increased, from -7.9 to -15.3 for apprentices and -7.2 to -10.0 for auto-body shop workers. Results support the American Thoracic Society's recommended maximum of 16 mg/ml and provide evidence that extending the dose range beyond that does not increase sensitivity, whereas stopping before 16 may exaggerate response. Furthermore, to ensure validity, neither slope nor PC(20) should be extrapolated beyond data.

Adult↗