Objectives This report describes the extended follow-up (1941-2015) of a cohort of 38 549 automobile manufacturing workers with potential exposure to metalworking fluids (MWF). The outcomes of ...interest were mortality from cancers of the esophagus, stomach, intestine, rectum, bladder, liver, pancreas, larynx, lung, skin, prostate, brain, and female breast, as well as leukemia. This report includes 5472 deaths from cancer, more than ten times the numbers of deaths in our last summary report published 20 years ago. Methods Standardized mortality ratios were computed for the entire study period. Adjusted hazard ratios (HR) were estimated in Cox proportional hazard models with categorical variables for cumulative exposure to each type of MWF. Results Exposure-response patterns are consistent with prior mortality reports from this cohort. We found increased risk of skin and female breast cancer with straight fluids. For the first time, we found elevated risk of stomach cancer mortality. Overall, many of the exposure-response results did not suggest an association with MWF. Conclusions Mortality is a poor proxy for cancer diagnosis for treatable cancers and not the optimal outcome measure in etiological studies. Although the HR presented here handle bias from the healthy worker hire effect and left truncation, they do not handle bias from healthy worker survivor effect, which likely results in underestimates of the health impacts of MWF. Although this updated summary provides some information on the risk of cancer from MWF, targeted future analyses will help clarify associations.
Wildfires in the Western United States are a growing and significant source of air pollution that is eroding decades of progress in air pollution reduction. The effects on preterm birth during ...critical periods of pregnancy are unknown.
We assessed associations between prenatal exposure to wildland fire smoke and risk of preterm birth (gestational age < 37 weeks). We assigned smoke exposure to geocoded residence at birth for all live singleton births in California conceived 2007–2018, using weekly average concentrations of particulate matter ≤ 2.5 µm (PM2.5) attributable to wildland fires from United States Environmental Protection Agency’s Community Multiscale Air Quality Model. Logistic regression yielded odds ratio (OR) for preterm birth in relation to increases in average exposure across the whole pregnancy, each trimester, and each week of pregnancy. Models adjusted for season, age, education, race/ethnicity, medical insurance, and smoking of the birthing parent.
For the 5,155,026 births, higher wildland fire PM2.5 exposure averaged across pregnancy, or any trimester, was associated with higher odds of preterm birth. The OR for an increase of 1 µg/m3 of average wildland fire PM2.5 during pregnancy was 1.013 (95 % CI:1.008,1.017). Wildland fire PM2.5 during most weeks of pregnancy was associated with higher odds. Strongest estimates were observed in weeks in the second and third trimesters. A 10 µg/m3 increase in average wildland fire PM2·5 in gestational week 23 was associated with OR = 1.034; 95 % CI: 1.019, 1.049 for preterm birth.
Preterm birth is sensitive to wildland fire PM2.5; therefore, we must reduce exposure during pregnancy.
•Average intensity of diesel exhaust and dust exposure were associated with COPD.•Cumulative exposures were inversely related with the outcome in traditional regression.•Survivor bias was evident in ...the analysis of COPD in this population of exposed miners.
Diesel exhaust and respirable dust exposures in the mining industry have not been studied in depth with respect to non-malignant respiratory disease including chronic obstructive pulmonary disease (COPD), with most available evidence coming from other settings.
To assess the relationship between occupational diesel exhaust and respirable dust exposures and COPD mortality, while addressing issues of survivor bias in exposed miners.
The study population consisted of 11,817 male workers from the Diesel Exhaust in Miners Study II, followed from 1947 to 2015, with 279 observed COPD deaths. We fit Cox proportional hazards models for the relationship between respirable elemental carbon (REC) and respirable dust (RD) exposure and COPD mortality. To address healthy worker survivor bias, we leveraged the parametric g-formula to assess effects of hypothetical interventions on both exposures.
Cox models yielded elevated estimates for the associations between average intensity of REC and RD and COPD mortality, with hazard ratios (HR) corresponding to an interquartile range width increase in exposure of 1.46 (95 % confidence interval (CI): 1.12, 1.91) and 1.20 (95 % CI: 0.96, 1.49), respectively for each exposure. HRs for cumulative exposures were negative for both REC and RD. Based on results from the parametric g-formula, the risk ratio (RR) for COPD mortality comparing risk under an intervention eliminating REC to the observed risk was 0.85 (95 % CI: 0.55, 1.06), equivalent to an attributable risk of 15 %. The corresponding RR comparing risk under an intervention eliminating RD to the observed risk was 0.93 (95 % CI: 0.56, 1.31).
Our findings, based on data from a cohort of nonmetal miners, are suggestive of an increased risk of COPD mortality associated with REC and RD, as well as evidence of survivor bias in this population leading to negative associations between cumulative exposures and COPD mortality in traditional regression analysis.
Suicides, overdoses, and drug-related liver diseases (deaths of despair) are greatly elevated in the mining and extraction industries compared to other industries. To better understand the drivers of ...these deaths, we examined suicide or overdose mortality in relation to age at worker exit among a retrospective cohort of 11,009 male mine workers from the Diesel Exhaust in Miners Study II.
We calculated age-adjusted mortality rates (1947–2015) and estimated hazard ratios (HRs) and 95% Confidence Intervals (CI) for suicide or overdose death in relation to age at worker exit (leaving work). The mining industry curtailed its workforce in the early 1980s due to economic downturn; therefore, separate models were fit for worker exit pre- and post-1980.
Suicide deaths peaked between 1980 and 1989 at 67.2 per 100,000, more than double the rate in the general population. The hazard rate for suicide or overdose was 2.56 times higher for inactive versus actively employed workers (95% CI: 1.88, 3.50). Based on 187 suicides or overdoses, associations between younger age at worker exit and suicide or overdose death were null or protective before 1980. However post-1980, those who exited between ages 30–39 years had an elevated risk of death HR = 1.33, 95% CI (0.70, 2.53) and those who exited before age 30 had a HR for suicide or overdose of 1.57 (0.83, 2.96) compared to those who exited work after age 55.
Worker exit may contribute to the elevated mortality from suicide or overdose among male mine workers, particularly among younger age groups.
•Among male mine workers, rates of suicide and overdose remained above US males.•The suicide or overdose rate was higher for inactive versus actively employed mine workers.•Exiting work post-1980, increased the risk of suicide or overdose.•Economic decline and exiting work at <55 years increased suicide or overdose risk.
Objectives To examine gender and racial disparities in ischaemic heart disease (IHD) mortality related to metalworking fluid exposures and in the healthy worker survivor effect. Methods A cohort of ...white and black men and women autoworkers in the USA was followed from 1941 to 1995 with quantitative exposure to respirable particulate matter from water-based metalworking fluids. Separate analyses used proportional hazards models and g-estimation. Results The HR for IHD among black men was 3.29 (95% CI 1.49 to 7.31) in the highest category of cumulative synthetic fluid exposure. The HR for IHD among white women exposed to soluble fluid reached 2.44 (95% CI 0.96 to 6.22). However, no increased risk was observed among white men until we corrected for the healthy worker survivor effect. Results from g-estimation indicate that if white male cases exposed to soluble or synthetic fluid had been unexposed to that fluid type, then 1.59 and 1.20 years of life would have been saved on average, respectively. Conclusions We leveraged the strengths of two different analytic approaches to examine the IHD risks of metalworking fluids. All workers may have the same aetiological risk; however, black and female workers may experience more IHD from water-based metalworking fluid exposure because of a steeper exposure–response or weaker healthy worker survivor effect.
Background: Temperature changes have been associated with increased cardiovascular risk, but the role of inflammatory markers in this relationship is not well understood. The objective of this study ...was to analyze the association between air temperature and C-reactive protein, interleukin-6 and fibrinogen in postmyocardial infarction patients. Methods: In a multicenter panel study, the 3 inflammatory blood markers were measured repeatedly. In total, 5813 blood samples in 1003 subjects were collected in 6 European cities representing different climates. Data on patient characteristics and disease history were gathered at the baseline visit. Meteorologic data were obtained from the city-specific network stations. The association was analyzed using a semiparametric model with random patient effects. Results: A 10°C decrease in the 5-day-average of air temperature before the blood withdrawal was associated with a 4% increase in C-reactive protein (4.3% 95% confidence interval = 0.2% to 8.1%). Correspondingly, an increase of interleukin-6 was observed for the same time window (3.3% 0.1% to 6.3%) whereas fibrinogen showed an increase of 1.3% (0.2% to 2.4%) with a lag of 3 days. Conclusion: A decrease in air temperature, particularly the average temperature of the last 5 days, was associated with an increase in both C-reactive protein and interleukin-6, whereas fibrinogen seemed to react to temperature changes after 3 days. In susceptible patients this might lead to an additional risk for cardiovascular events and suggests a biologic mechanism for the observed seasonal variation in death from ischemic heart disease and stroke in the elderly.
Suicide, drug overdose, and alcohol-related liver disease (ALD) mortality have been rising in the United States. While suicide and overdose have received a great deal of attention, far less public ...health concern has focused on chronic ALD. To address this gap, we examine ALD mortality rates, by race, in a cohort of autoworkers to describe trends over the past 75 years, from the peak in automobile manufacturing employment through its decline.
Based on the United Autoworkers-General Motors (UAW-GM) cohort we estimated temporal trends in age-adjusted ALD mortality rates from 1941 through 2015 at three automobile manufacturing plants in Michigan. We compared these rates to county, state, and U.S. rates, directly standardized to the 2000 U.S. census, to assess the roles of race and employment on ALD mortality.
The overall age-adjusted ALD mortality rate among 41,097 male autoworkers peaked at 46.1 per 100,000 in the 1970s, followed by a gradual decline and a recent rise. Rates were slightly higher for black than white men until early 2000s, when rates increased only for white men. ALD mortality rates in the study cohort tracked national, state, and county rates for white men until the most recent time period, but were lower throughout the study period for black men, especially in the 1970s and 1980s.
Employment in automobile manufacturing may have offered some protection against death from ALD for black men, and loss of those manufacturing jobs may have impacted white men without a college degree more in recent decades.
•In a cohort of autoworkers, the alcohol-related liver disease (ALD) mortality rate has declined from its peak in the 1970s.•ALD mortality was lower for black male autoworkers than for black men in the general population of the county, state, or US.•ALD mortality was higher for black than white male autoworkers until 2000, when rates increased only for white autoworkers.•Union jobs in Michigan automobile manufacturing may have offered some protection against risk of ALD for black men.•Recent loss of US manufacturing jobs may have impacted white men more than black men without a college degree.
In the presence of time-varying confounders affected by prior treatment, standard statistical methods for failure time analysis may be biased. Methods that correctly adjust for this type of covariate ...include the parametric g-formula, inverse probability weighted estimation of marginal structural Cox proportional hazards models, and g-estimation of structural nested accelerated failure time models. In this article, we propose a novel method to estimate the causal effect of a time-dependent treatment on failure in the presence of informative right-censoring and time-dependent confounders that may be affected by past treatment: g-estimation of structural nested cumulative failure time models (SNCFTMs). An SNCFTM considers the conditional effect of a final treatment at time m on the outcome at each later time k by modeling the ratio of two counterfactual cumulative risks at time k under treatment regimes that differ only at time m. Inverse probability weights are used to adjust for informative censoring. We also present a procedure that, under certain "no-interaction" conditions, uses the g-estimates of the model parameters to calculate unconditional cumulative risks under nondynamic (static) treatment regimes. The procedure is illustrated with an example using data from a longitudinal cohort study, in which the "treatments" are healthy behaviors and the outcome is coronary heart disease.
PDF
