Mortality Study (mortality + study)

Distribution by Scientific Domains

Selected Abstracts

Brain cancer mortality and potential occupational exposure to lead: Findings from the National Longitudinal Mortality Study, 1979,1989

Edwin van Wijngaarden
Abstract We evaluated the association between potential occupational lead exposure and the risk of brain cancer mortality in the National Longitudinal Mortality Study (NLMS), which is a prospective census-based cohort study of mortality among the noninstitutionalized United States population (1979,1989). The present study was limited to individuals for whom occupation and industry were available (n = 317,968). Estimates of probability and intensity of lead exposure were assigned using a job-exposure matrix (JEM). Risk estimates for the impact of lead on brain cancer mortality were computed using standardized mortality ratio (SMR) and proportional hazards and Poisson regression techniques, adjusting for the effects of age, gender and several other covariates. Brain cancer mortality rates were greater among individuals in jobs potentially involving lead exposure as compared to those unexposed (age- and gender-adjusted hazard ratio (HR) = 1.5; 95% confidence interval (CI) = 0.9,2.3) with indications of an exposure,response trend (probability: low HR = 0.7 (95% CI = 0.2,2.2), medium HR = 1.4 (95% CI = 0.8,2.5), high HR = 2.2 (95% CI = 1.2,4.0); intensity: low HR = 1.2 (95% CI = 0.7,2.1), medium/high HR = 1.9 (95% CI = 1.0,3.4)). Brain cancer risk was greatest among individuals with the highest levels of probability and intensity (HR = 2.3; 95% CI = 1.3,4.2). These findings provide further support for an association between occupational lead exposure and brain cancer mortality, but need to be interpreted cautiously due to the consideration of brain cancer as one disease entity and the absence of biological measures of lead exposure. 2006 Wiley-Liss, Inc. [source]

Development of historical exposure estimates of cosmic radiation and circadian rhythm disruption for cohort studies of Pan Am flight attendants,,

Martha A. Waters PhD
Abstract Background The National Institute for Occupational Safety and Health is conducting cohort studies of flight crew employed by the former Pan American World Airways company (Pan Am) as part of an effort to examine flight crew workplace exposures and health effects. Flight crew are exposed to elevated levels of cosmic radiation and to disruption of circadian rhythm when flying across multiple time zones. Methods exist to calculate cosmic radiation effective doses on individual flights; however, only work histories which provided an employee's domicile (home base) history rather than a record of every flight flown were available. Methods/Results We developed a method for estimating individual cumulative domicile-based cosmic radiation effective doses and two metrics for circadian rhythm disruption for each flight attendant: cumulative times zones crossed and cumulative travel time during the standard sleep interval. Conclusions The domicile-exposure matrix developed was used to calculate exposure estimates for a cohort mortality study of former Pan Am flight attendants. Am. J. Ind. Med. 52:751,761, 2009. Published 2009 Wiley-Liss, Inc. [source]

A cohort mortality study of chemical laboratory workers at Department of Energy Nuclear Plants,

Travis Kubale PhD
Abstract Objective This study evaluates the mortality experience of 6,157 chemical laboratory workers employed at United States Department of Energy facilities. Methods All cause, all cancer and cause-specific standardized mortality ratios were calculated. Cox regression analyses were conducted to further evaluate the relation between chemical exposure and mortality risk due to selected cancers. Results The mortality due to all causes combined and all cancers combined were below expectation for the cohort. There were no statistically significant elevations reported among males for any specific cancer or non-cancer outcome. There no statistically significant elevations among females for any specific non-cancer and most specific cancers; however, multiple myeloma deaths were significantly elevated (SMR,=,3.56; 95% CI,=,1.43,7.33; number of observed deaths, n,=,7). Statistically significant elevations were seen among workers employed 20+ years for leukemia using both 2- and 5-year lag periods. Also, a statistically significant positive trend of elevated lung cancer mortality with increasing employment duration was seen using both 5- and 10-year lags. A similar trend was seen for smoking related cancers among men. Conclusion While lymphatic and hematopoietic cancer mortality was below expectation, a significant elevation of multiple myeloma deaths among females and an elevation of leukemia among workers employed 20+ years (possibly due to radiation and benzene exposure) were observed. A NIOSH case,control study is underway to examine more closely the relation between multiple myeloma and a variety of chemical exposures among workers employed at the Oak Ridge K-25 facility. Am. J. Ind. Med. 51:656,667, 2008. Published 2008 Wiley-Liss, Inc. [source]

Cancer incidence and mortality in aircraft maintenance workers,

Catherine D'Este PhD
Abstract Background A cancer incidence and mortality study was conducted in response to health concerns raised by workers from F-111 aircraft deseal/reseal fuel tank maintenance programs, to determine whether personnel exposed to deseal/reseal had an excess of cancers and mortality. Methods Number of deaths and cancers for individuals involved in F-111 DSRS activities were matched against two Air Force comparison groups. Analyses were weighted to adjust for differences in age, exposure period and rank. Results Eight hundred seventy-three exposed, 7,577 comparison group one, and 9,408 comparison group two individuals were matched against death and cancer data, with 431 cancers and 431 deaths. Cancer incidence was higher in the exposed group, with marginally significant increases of 40,50% (cancer incidence rate ratio range 1.45,1.62). Exposed group mortality was significantly lower than both comparison groups, likely due to survivor bias in the exposed group (mortality rate ratio range 0.33,0.44). Conclusions On the balance of probabilities, there is an increased risk of cancer associated with participation in F-111 deseal/reseal activities. Am. J. Ind. Med. 51:16,23, 2008. 2007 Wiley-Liss, Inc. [source]

Carbon black and lung cancer: Testing a new exposure metric in a German cohort

Peter Morfeld PhD
Abstract Background A cohort mortality study of a large carbon black production plant in Germany showed an elevation in lung cancer mortality (SMR 1.81 (95% CI: 1.34,2.39)), although the elevation could not be linked to exposure to carbon black. Methods In follow up to a British study of carbon black production workers [Sorahan et al., 2007] in which risk of lung cancer progressively declined after cessation of employment,in contrast to an expected upward trend,we evaluated the German cohort with a similar methodology, that is, by focusing on the first 15 years after leaving employment in terms of lung cancer SMR. Results In our SMR analysis of the German cohort of 1,528 men and an inception cohort of 1,271 men, distinctly different results from the British cohort were observed. We observed a rising trend in lung cancer SMR, in contrast to the declining SMR trend noted in the British cohort. In fact, Cox models for lung cancer mortality with attained age as the basic time variable showed negative coefficients for the full and inception cohorts. Conclusions Our analysis of a large German cohort of carbon black workers does not support the concept of a declining risk of lung cancer following cessation of employment. Am. J. Ind. Med. 50:565,567, 2007. 2007 Wiley-Liss, Inc. [source]

Mortality of workers employed in shoe manufacturing: An update,

Everett J. Lehman MS
Abstract Background In the late 1970s, the National Institute for Occupational Safety and Health identified two shoe manufacturing facilities where workers experienced relatively "pure" exposures to toluene. A mortality study was conducted through December 31, 1982. An original study did not detect elevated leukemia mortality but did detect increased lung cancer mortality. The present study is an update of the mortality of the original cohort. Methods The study cohort consisted of workers employed 1 month or more between 1940 and 1979 at two Ohio shoe manufacturing plants. Vital status was ascertained through December 31, 1999. Results Seven thousand eight hundred twenty eight workers, contributing 300,777 person years, were available for analysis. An excess of lung cancer deaths persisted with additional years of follow-up (SMR,=,1.36, 95% confidence interval (CI),=,1.19,1.54). Trend tests did not indicate a positive trend between lung cancer risk and duration of employment. Mortality from leukemia was not significantly elevated in the updated analysis. Conclusions Results indicate a possible association between lung cancer mortality and exposure to chronic, low-levels of organic solvents. Although the strength of this conclusion was weakened by the lack of increasing lung cancer risk in relation to duration of employment, other studies have supported this association. Am. J. Ind. Med. 49:535,546, 2006. Published 2006 Wiley-Liss, Inc. [source]

A proportionate mortality study of bricklayers and allied craftworkers,

Joyce Salg PhD
Abstract Background Mortality among members of the International Union of Bricklayers and Allied Craftworkers (IUBAC) is examined. Bricklayers and allied craft workers may be exposed to cobalt, epoxy resins, pitch, lime, and to lung carcinogens such as asbestos, silica, and nickel. Methods Proportionate mortality ratios (PMRs) were computed using US age-, gender-, and race-specific mortality rates for members who died during 1986,1991. Results Statistically significant PMRs among white men were found for cancers of the esophagus (PMR,=,134), stomach (PMR,=,131), respiratory system, trachea, bronchus, and lung (PMR,=,144), other parts of the respiratory system (PMR,=,216), other and unspecified sites (PMR,=,125). Elevated PMRs were also found for other diseases of the blood and blood forming organs (PMR,=,201), emphysema (PMR,=,133) and for asbestosis (PMR,=,554), and other respiratory diseases (PMR,=,119). Conclusions Results are consistent with those found in previous studies, and suggest the need for intervention activities directed at the prevention of these cancers, and other respiratory diseases. Am. J. Ind. Med. 47:10,19, 2005. Published 2004 Wiley-Liss, Inc. [source]

Cohort mortality study of Philadelphia firefighters

Dalsu Baris MD
Abstract Background Fire fighters are exposed to a wide variety of toxic chemicals. Previous studies have reported excess risk of some cancers but have been limited by small numbers or little information on employment characteristics. Methods We conducted a retrospective cohort mortality study among 7,789 Philadelphia firefighters employed between 1925 and 1986. For each cause of death, the standardized mortality ratios (SMRs) and 95% confidence intervals were estimated. We also compared mortality among groups of firefighters defined by the estimated number of career runs and potential for diesel exposure. Results In comparison with U.S. white men, the firefighters had similar mortality from all causes of death combined (SMR,=,0.96) and all cancers (SMR,=,1.10). There were statistically significant deficits of deaths from nervous system diseases (SMR,=,0.47), cerebrovascular diseases (SMR,=,0.83), respiratory diseases (SMR,=,0.67), genitourinary diseases (SMR,=,0.54), all accidents (SMR,=,0.72), and suicide (SMR,=,0.66). Statistically significant excess risks were observed for colon cancer (SMR,=,1.51) and ischemic heart disease (SMR,=,1.09). The risks of mortality from colon cancer (SMR,=,1.68), kidney cancer (SMR,=,2.20), non-Hodgkin's lymphoma (SMR,=,1.72), multiple myeloma (SMR,=,2.31), and benign neoplasms (SMR,=,2.54) were increased among firefighters with at least 20 years of service. Conclusions Our study found no significant increase in overall mortality among Philadelphia firefighters. However, we observed increased mortality for cancers of the colon and kidney, non-Hodgkin's lymphoma and multiple myeloma. There was insufficient follow-up since the introduction of diesel equipment to adequately assess risk. Am. J. Ind. Med. 39:463,476, 2001. Published 2001 Wiley-Liss, Inc. [source]

Regression Calibration in Semiparametric Accelerated Failure Time Models

BIOMETRICS, Issue 2 2010
Menggang Yu
Summary In large cohort studies, it often happens that some covariates are expensive to measure and hence only measured on a validation set. On the other hand, relatively cheap but error-prone measurements of the covariates are available for all subjects. Regression calibration (RC) estimation method (Prentice, 1982,,Biometrika,69, 331,342) is a popular method for analyzing such data and has been applied to the Cox model by Wang et al. (1997,,Biometrics,53, 131,145) under normal measurement error and rare disease assumptions. In this article, we consider the RC estimation method for the semiparametric accelerated failure time model with covariates subject to measurement error. Asymptotic properties of the proposed method are investigated under a two-phase sampling scheme for validation data that are selected via stratified random sampling, resulting in neither independent nor identically distributed observations. We show that the estimates converge to some well-defined parameters. In particular, unbiased estimation is feasible under additive normal measurement error models for normal covariates and under Berkson error models. The proposed method performs well in finite-sample simulation studies. We also apply the proposed method to a depression mortality study. [source]