Effects of occupational exposure to respirable quartz dust on acute myocardial infarction.

OBJECTIVES: The aim of this study is to investigate the effects of occupational exposure to respirable quartz (RQ) on first acute myocardial infarction (AMI). RQ causes pulmonary diseases like silicosis and has also been linked to cardiovascular diseases. Inflammation is hypothesised as the underlying pathway. METHODS: We performed a 1:3 matched case-control study nested in a cohort of male uranium miners. We included cases (identified from hospital records and validated according to WHO criteria) who had suffered their first AMI while still employed and <65 years of age. Controls were matched by date of birth and Wismut recruitment era. RQ exposure was derived from a job-exposure matrix. We performed a conditional logistic regression adjusted for smoking, metabolic syndrome and baseline erythrocyte sedimentation rate. Subgroups by date of birth and Wismut recruitment era were analysed to minimise the impact of pre-exposures. RESULTS: The study base comprised 292 matched sets. The cumulative exposure ranged from 0 to 38.9 mg/m3-years RQ. The adjusted OR of the highest RQ tertile (>14.62 mg/m3-years) was 1.27 (95% CI 0.82 to 1.98). However, for miners born after 1928 and hired in the earliest recruitment era (1946-1954), a significantly elevated risk was seen in the highest RQ tertile (OR=6.47 [95% CI 1.33 to 31.5]; 50 matched sets). CONCLUSIONS: An impact of quartz dust on first AMI was observed only in a small subgroup that had virtually no pre-exposure to RQ. Further studies on the basis of complete occupational history are required to substantiate this finding.

Occupational exposure to respirable crystalline silica and chronic non-malignant renal disease: systematic review and meta-analysis.

BACKGROUND: While occupational exposure to respirable silica is known to lead to lung disease, most notably silicosis, its association with chronic kidney disease is unclear. OBJECTIVES: This review explores the association between occupational exposure to respirable silica and chronic non-malignant renal disease such as glomerulonephritis. The evidence has been collected and compiled. Possible sources of bias are thoroughly discussed. METHODS: Cohort studies with silica exposure and case-control studies of renal disease were searched in PubMed until January 2015. Two authors independently abstracted data; any disagreement was resolved by consulting a third reviewer. A meta-analysis was performed to evaluate the association to silica exposure. RESULTS: A total of 23 cohort and four case-control studies were included in the analysis. The meta-analysis of cohort studies yielded elevated overall SMRs for renal disease. Some studies, however, included dose-response analyses, most of which did not show a positive trend. The approaches and results of the case-control studies were very heterogeneous. CONCLUSIONS: While the studies of cohorts exposed to silica found elevated SMRs for renal disease, no clear evidence of a dose-response relationship emerged. The elevated risk may be attributed to diagnostic and methodological issues. In order to permit a reliable estimation of a possible causal link, exposed cohorts should be monitored for renal disease, as the information from mortality studies is hardly reliable in this field.

Diesel motor exhaust and lung cancer mortality: reanalysis of a cohort study in potash miners.

The aim of the reanalysis is to reassess lung cancer risk associated with occupational exposure to diesel motor exhaust in potash miners, while controlling for potential confounders such as smoking and previous occupational history. Our investigation is based on a cohort study of nearly 6,000 German potash miners, who were followed up from 1970 to 2001. The reanalysis also takes into account the employment periods before potash mining, in particular uranium mining. Different approaches (nested case-control study and Cox model) were used to adjust for confounding. The exposure estimates were recalculated, lagging the exposure by 5 years. Exposure groups were defined by tertiles of cumulative respirable elemental carbon (REC) exposure estimates and occupational categories, where exposure was estimated originally by representative measurements of total carbon for different occupations. The highest REC concentration was measured for production workers, about twice as much as for other occupations. The reanalysis revealed that while about 4 % of all study subjects had worked earlier in uranium mines, 10.3 % of later lung cancer cases did so. Although their absolute number was small, the corresponding relative risk estimator was significantly elevated. Our analysis did not show any notable association between cumulative REC exposure and lung cancer risk. Introducing cumulative REC exposure as a continuous variable into the conditional logistic regression model yielded an odds ratio of OR = 1.04 [0.70-1.53]95 % adjusted for smoking and previous employment. The study results give no evidence for an association between REC exposure and lung cancer risk. Only for very high cumulative dose, corresponding to at least 20 years of exposure in the production area, some weak hints for a possible risk increase could be detected. The study underlines the importance of assessing the entire occupational history in occupational studies, especially if the supposed dose-response-relationship is weak.

Chronic obstructive pulmonary disease and longitudinal changes in pulmonary function due to occupational exposure to respirable quartz.

OBJECTIVES: The present study sought to examine the long-term effects of exposure to respirable quartz on pulmonary function with particular focus on chronic obstructive pulmonary disease (COPD). METHODS: The study is based on the Wismut cohort of former uranium miners. Spirometric data were ascertained together with quantitative estimates of cumulative exposure to respirable quartz for each of 1421 study subjects born between 1954 and 1956. The case definition for COPD is based on the criteria of the Global Initiative for Chronic Obstructive Lung Disease. Linear mixed regression models were fitted to identify significant determinants of longitudinal changes in lung function parameters. RESULTS: An average of five spirometries were available for each miner. It was shown that cumulative exposure to 1 mg/m(3)-year respirable quartz leads, on average, to a relative reduction in forced expiratory volume in 1 s/ orced vital capacity (FEV(1)/FVC) of 2.75% (p<0.001). A nested case-control approach demonstrated that the risk for COPD stage I increases with increasing cumulative exposure to respirable quartz (OR 1.81 per 1 mg/m(3)-year). CONCLUSIONS: This paper adds further evidence on the long-term effects of exposure to respirable quartz, which include a decline in pulmonary function parameters and an increase in the incidence of COPD.

Occupational and diagnostic exposure to ionizing radiation and leukemia risk among German uranium miners.

Lung cancer is a well-known effect of radon exposure in uranium mines. However, little is known about the induction of leukemia by radiation exposure in mines. Moreover, miners usually have occupational medical checkup programs that include chest x-ray examinations. Therefore, the aim of the present study was to re-examine leukemia risk among miners, taking into account exposure to x rays for diagnostic purposes. The data used were from a previously analyzed individually matched case-control study of former uranium miners in East Germany with 377 cases and 980 controls. Additionally, data on x-ray examinations were taken from medical records for most of the subjects. Finally, the absorbed dose to red bone marrow was calculated considering both occupational and diagnostic exposures. Using conditional logistic regression models, a moderately but not statistically significant elevated risk was seen in the dose category above 200 mGy for the combined dose from both sources [odds ratio (OR) = 1.33, 90% confidence interval (CI): (0.82-2.14)]. Ignoring the dose accumulated in the recent 20 y, the risk in the highest dose category (>105 mGy) was higher [OR = 1.77, 90% CI: (1.06-2.95)]. Ignoring diagnostic exposure yielded similar results. For the highest dose category (absorbed dose lagged by 20 y) the risk was more than doubled [OR = 2.64, 90% CI: (1.60-4.35)].