Coal mine dust exposure and spirometry in experienced miners

Cross-shift changes in pulmonary function and occupational exposure to particulate matter among e-waste workers in Ghana

Introduction

Little is known on the association between cross-shift changes in pulmonary function and personal inhalation exposure to particulate matter (PM) among informal electronic-waste (e-waste) recovery workers who have substantial occupational exposure to airborne pollutants from burning e-waste.

Methods

Using a cross-shift design, pre- and post-shift pulmonary function assessments and accompanying personal inhalation exposure to PM (sizes <1, <2.5 μm, and the coarse fraction, 2.5-10 μm in aerodynamic diameter) were measured among e-waste workers (n = 142) at the Agbogbloshie e-waste site and a comparison population (n = 65) in Accra, Ghana during 2017 and 2018. Linear mixed models estimated associations between percent changes in pulmonary function and personal PM.

Results

Declines in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) per hour were not significantly associated with increases in PM (all sizes) among either study population, despite breathing zone concentrations of PM (all sizes) that exceeded health-based guidelines in both populations. E-waste workers who worked "yesterday" did, however, have larger cross-shift declines in FVC [-2.4% (95%CI: -4.04%, -0.81%)] in comparison to those who did not work "yesterday," suggesting a possible role of cumulative exposure.

Discussion

Overall, short-term respiratory-related health effects related to PM exposure among e-waste workers were not seen in this sample. Selection bias due to the "healthy worker" effect, short shift duration, and inability to capture a true "pre-shift" pulmonary function test among workers who live at the worksite may explain results and suggest the need to adapt cross-shift studies for informal settings.

High exposure mining occupations are associated with obstructive lung disease, National Health Interview Survey (NHIS), 2006-2015

BACKGROUND

The association between mining occupation categories and obstructive lung disease (OLD) has not been well explored in the United States.

METHODS

National Health Interview Survey (NHIS) data from 2006 to 2015 was used to determine the relationship between mining occupations and diagnosis of chronic bronchitis, emphysema, chronic obstructive pulmonary disease (COPD), and asthma. We classified occupations into low, moderate, high, and very high dust exposure groups. Extraction workers were categorized as very high dust exposure.

RESULTS

We found 4.5% of miners had chronic bronchitis, 3.3% had emphysema, 6.2% had COPD, and 9.9% had asthma. In fully adjusted models, extraction workers had significantly increased odds of having chronic bronchitis (OR = 2.18 [95%CI: 1.02, 4.64]), emphysema (OR = 7.85 [95%CI: 1.70, 36.27]), and COPD (OR = 2.56 [95%CI: 1.29, 5.12]) compared to lower exposure occupations.

CONCLUSIONS

Occupation is an important predictor of OLD in the mining industry.

A case-control study of airways obstruction among construction workers

BACKGROUND

While smoking is the major cause of chronic obstructive pulmonary disease (COPD), occupational exposures to vapors, gases, dusts, and fumes (VGDF) increase COPD risk. This case-control study estimated the risk of COPD attributable to occupational exposures among construction workers.

METHODS

The study population included 834 cases and 1243 controls participating in a national medical screening program for older construction workers between 1997 and 2013. Qualitative exposure indices were developed based on lifetime work and exposure histories.

RESULTS

Approximately 18% (95% CI = 2-24%) of COPD risk can be attributed to construction-related exposures, which are additive to the risk contributed by smoking. A measure of all VGDF exposures combined was a strong predictor of COPD risk.

CONCLUSIONS

Construction workers are at increased risk of COPD as a result of broad and complex effects of many exposures acting independently or interactively. Control methods should be implemented to prevent worker exposures, and smoking cessation should be promoted.

Underground Coal Mining: Relationship between Coal Dust Levels and Pneumoconiosis, in Two Regions of Colombia, 2014

In Colombia, coal miner pneumoconiosis is considered a public health problem due to its irreversibility, high cost on diagnosis, and lack of data related to its prevalence in the country. Therefore, a cross-sectional study was carried out in order to determine the prevalence of pneumoconiosis in underground coal mining workers in two regions of Colombia. The results showed a 35.9% prevalence of pneumoconiosis in the study group (42.3% in region 1 and 29.9% in region 2). An association was found between a radiologic diagnosis of pneumoconiosis and a medium risk level of exposure to carbon dust (OR: 2.901, 95% CI: 0.937, 8.982), medium size companies (OR: 2.301, 95% CI: 1.260–4.201), length of mining work greater than 25 years (OR: 3.222, 95% CI: 1.806–5.748), and a history of smoking for more than one year (OR: 1.479, 95% CI: 0.938–2.334). These results establish the need to generate an intervention strategy aimed at preventing the identified factors, as well as a timely identification and effective treatment of pneumoconiosis in coal miners, in which the commitment of the General Health and Social Security System and the workers compensation system is ensured.

Results from a Ukrainian-US collaborative study: prevalence and predictors of respiratory symptoms among Ukrainian coal miners

BACKGROUND

Underground coal mining is an expanding industry in Ukraine, yet little is known about the burden of respiratory disease among Ukrainian miners.

METHODS

A Fogarty International Center-supported collaboration between researchers at the University of Illinois and the Institute of Occupational Health in Kyiv, Ukraine formed to improve capacity for conducting and monitoring medical surveillance among Ukrainian coal miners. A cross-sectional survey among a random sample of working and former miners was conducted; demographic, work, and health information were collected using a standardized questionnaire. Weighted prevalence rates were calculated and predictors of respiratory symptoms explored.

RESULTS

Improvements in infrastructure, including spirometry and chest radiography testing, transformed medical surveillance among these miners. Results from the health study included that the prevalence of respiratory symptoms was higher among former compared to current miners (shortness of breath 35.6% vs. 5.1%; chronic bronchitis 18.1% vs. 13.9%, respectively). A statistically significant exposure-response relationship was observed between years mining and respiratory symptoms in former miners and between years mining at the coal face and respiratory symptoms among current miners. Evidence of downward bias from the healthy worker survivor effect was observed.

CONCLUSIONS

This successful international collaboration built a sustainable infrastructure for conducting workplace medical surveillance and research. The resulting study was the first in the western literature to report on respiratory symptoms in this population; likely underestimation of disease rates due to selection and measurement biases was demonstrated. Efforts should continue to build this collaboration and to characterize and reduce respiratory illness among Ukrainian coal miners.

Cross-shift peak expiratory flow changes are unassociated with respirable coal dust exposure among South African coal miners

BACKGROUND

The objectives of this study were to determine whether cross-shift changes in peak expiratory flow rate (PEFR) were related to respirable dust exposure in South African coalminers.

METHODS

Fifty workers were randomly selected from a cohort of 684 miners from 3 bituminous coalmines in Mpumalanga, South Africa. Peak expiratory efforts were measured prior to the commencement of the shift, and at the end of the shift on at least two occasions separated by at least 2 weeks, with full shift personal dust sampling being conducted on each occasion for each participant. Interviews were conducted, work histories were obtained and cumulative exposure estimates were constructed. Regression models examined the associations of cross-shift changes in PEFR with current and cumulative exposure, controlling for shift, smoking and past history of tuberculosis.

RESULTS

There were marginal differences in cross-shift PEFR (ranging from 0.1 to 2 L/min). Linear regression analyses showed no association between cross-shift change in PEFR and current or cumulative exposure. The specific shift worked by participants in the study showed no effect.

CONCLUSIONS

Our study showed no association between current respirable dust exposure and cross-shift changes in PEFR. There was a non-significant protective effect of cumulative dust exposure on the outcome, suggesting the presence of a "healthy worker survivor effect" in this data.

Evaluation of the relationship between radiological abnormalities and both pulmonary function and pulmonary hypertension in coal workers? pneumoconiosis

OBJECTIVE

The aim of this study was to investigate the effect of the radiological evidence of emphysema, and the extent of interstitial involvement, on lung function and pulmonary arterial pressure (PAP) in patients with coal workers' pneumoconiosis (CWP).

METHODS

The records of 48 patients with suspected CWP were evaluated retrospectively. Pulmonary function tests, arterial blood gas analyses and right heart catheterization were evaluated in all patients. Radiological scoring was according to International Labour Organization criteria, and emphysema was scored by CT scanning. Patients were grouped according to the mean PAP (> or =20 mm Hg or < or =19 mm Hg).

RESULTS

All patients showed a mild decrease in FEV(1)/FVC and a mild increase in FRC. Forty-four per cent of patients developed mild to moderate pulmonary hypertension. Emphysema scores correlated significantly with airflow rates, including FEV(1)%, FEV(1)/FVC and FEF(25-75%), and with carbon monoxide diffusing capacity (DLCO)% predicted as well as FRC% predicted and the ratio RV/TLC, which are indices of air trapping. Additionally, profusion and global profusion scores showed significant correlation with FEV(1)/FVC, DLCO% predicted, specific airway conductance and smoking. Mean PAP showed a significant negative correlation with FEF(50%) predicted, DLCO% predicted and profusion score.

CONCLUSIONS

The impairment of pulmonary function (mainly disturbance in airflow rates and air trapping) and pulmonary hypertension may be present, even in a simple form of CWP. The pulmonary function impairment in patients with CWP is likely to be attributable to the occurrence of emphysema. However, pulmonary hypertension was directly related to the profusion of pneumoconiotic nodules, which may result in obliteration of the vascular bed.

Airflow limitation among workers in a labour-intensive coal mine in Tanzania

OBJECTIVES

To describe the relationship between cumulative respirable dust and quartz exposure and lung functioning among workers in a labour-intensive coal mine.

METHODS

The study population comprised 299 men working at a coal mine in Tanzania. Lung function was assessed using a Vitalograph alpha III spirometer in accordance with American Thoracic Society recommendations. Multiple linear regression models were developed to study the relationship between forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC) and FEV(1)/FVC and the cumulative dust or quartz exposure while adjusting for age, height and ever smoking. To evaluate trends for dose response, cumulative exposure concentrations for respirable dust and quartz were ranked and categorized in quartiles and the highest decile, with the first quartile as the reference group. Logistic regression models were used to determine odds ratios for FEV(1)/FVC < 0.7 and FEV(1)% < 80 for categories of cumulative dust or quartz exposure.

RESULTS

The prevalence of FEV(1)/FVC < 0.7 among the workers was 17.3%. Workers in the development team (20.5%) had the highest prevalence of FEV(1)% < 80%. The estimates of the effects of cumulative exposure on FEV(1)/FVC were -0.015% per mg years m(-3) for respirable dust and -0.3% per mg years m(-3) for respirable quartz. In logistic regression models, the odds ratios for airway limitation (FEV(1)/FVC < 0.7) for the workers in the highest decile of cumulative dust and quartz exposure versus the referents were 4.36 (95% confidence interval: 1.06, 17.96) and 3.49 (0.92, 13.21), respectively. The upper 10% of workers by cumulative dust and quartz exposure also had higher odds ratios for predicted FEV(1)% < 80% than the reference group odds ratio: 10.38 (1.38, 78.13) and 14.18 (1.72, 116.59), respectively. The results must be interpreted with caution due to a possible healthy worker effect and selection bias.

CONCLUSION

Exposure to respirable coal mine dust was associated with airway limitation as measured by FEV(1)/FVC and predicted FEV(1)%.

A prospective cohort study among new Chinese coal miners: the early pattern of lung function change

AIMS

To investigate the early pattern of longitudinal change in forced expiratory volume in 1 second (FEV1) among new Chinese coal miners, and the relation between coal mine dust exposure and the decline of lung function.

METHODS

The early pattern of lung function changes in 317 newly hired Chinese underground coal miners was compared to 132 referents. This three year prospective cohort study involved a pre-employment and 15 follow up health surveys, including a questionnaire and spirometry tests. Twice a month, total and respirable dust area sampling was done. The authors used a two stage analysis and a linear mixed effects model approach to analyse the longitudinal spirometry data, and to investigate the changes in FEV1 over time, controlling for age, height, pack years of smoking, mean respirable dust concentration, the room temperature during testing, and the groupxtime interaction terms.

RESULTS

FEV1 change over time in new miners is non-linear. New miners experience initial rapid FEV1 declines, primarily during the first year of mining, little change during the second year, and partial recovery during the third year. Both linear and quadratic time trends in FEV1 change are highly significant. Smoking miners lost more FEV1 than non-smokers. Referents, all age less than 20 years, showed continued lung growth, whereas the miners who were under age 20 exhibited a decline in FEV1.

CONCLUSION

Dust and smoking affect lung function in young, newly hired Chinese coal miners. FEV1 change over the first three years of employment is non-linear. The findings have implications for both methods and interpretation of medical screening in coal mining and other dusty work: during the first several years of employment more frequent testing may be desirable, and caution is required in interpreting early FEV1 declines.

Differential respirable dust related lung function effects between current and former South African coal miners

Dust-related dose-response decrements in lung function among coal miners have been reported in several studies, with varying magnitudes across populations. Few studies have compared differences between current and former coal miners. No studies on dose response relationships with lung function have been conducted in South African coal mines, one of the top three producers of coal internationally. The objectives of this study were (1) to describe the relationship between respirable dust exposure and lung function among current and former South African coal miners and to determine whether differential dust related effects were present between these employment categories; (2) to examine dust related dose response relationships, controlling for potential confounding by smoking and a history of tuberculosis (TB). Six hundred and eighty-four current and 188 ex-miners from three bituminous coal mines in Mpumalanga Province were studied. Interviews assessing work histories, smoking profiles and other risk factors were conducted. Work histories were also obtained from company records. Standardised spirometry was performed by trained technicians. Cumulative respirable dust exposure (CDE) estimates were constructed from company-collected sampling and measurements conducted by the researchers. Regression models examined the associations of CDE with per cent predicted FEV(1) and FVC, controlling for smoking, past history of TB and employment status. A statistically significant decline in FEV(1) of 1.1 and 2.2 ml/mg-year/m(3) was found in representative 40-year-old, 1.7-m tall current and former miners, respectively. Significant differences were found between the highest and medium exposure categories. Ex-miners had a lower mean per cent predicted lung function than current miners for each cumulative exposure category, suggesting a "healthy worker" effect. Past history of TB contributed to 21 and 14% declines in per cent predicted FEV(1) and FVC, respectively. Thus, in this cohort, a dose-related decline in lung function was associated with respirable dust exposure, with a magnitude of effect similar to that seen in other studies and important differences between current and former employees. A "healthy worker" effect may have attenuated the magnitude of this relationship. TB was a significant contributor to lung function loss.

Lung function decrease in relation to pneumoconiosis and exposure to quartz-containing dust in construction workers

BACKGROUND

Prevalence of exposure related respiratory symptoms and decreases in lung function are unknown among quartz dust exposed construction workers.

METHODS

In a cross-sectional study (n = 1335), the occurrence of respiratory symptoms, was recorded and spirometric lung function was measured. Results were associated with exposure data and presence of radiographic abnormalities and compared with a reference population.

RESULTS

Pneumoconiosis (profusion category 1/1 or greater) was associated with increased risks of FEV(1) and FVC values in the lowest 5% group, and with group-based decreases of 270 ml/s and 180 ml, respectively. Average lung function of construction workers was somewhat lower compared to a Dutch reference population. Lung function was not associated with exposure, except for a reduction in FVC of 5 ml per year for those with higher exposure.

CONCLUSIONS

In quartz dust exposed construction workers obstructive and restrictive lung function loss was detected.

Update on respiratory disease from coal mine and silica dust

Coal mine and silica dust cause significant respiratory disease in spite of modern dust control regulations. Susceptible individuals in exposed populations may develop fibrosing lung disease, obstructive airways disease, including chronic bronchitis and emphysema, or lung cancer. A careful occupational history that elicits exposure to respiratory hazards is the cornerstone of an accurate diagnosis. Treatment involves removal from exposure, supportive care, pulmonary rehabilitation, and when disabling disease is present, assistance obtaining compensation.

Bronchial responsiveness and five-year FEV1 decline: a study in miners and nonminers

Increased nonspecific bronchial responsiveness (NSBR) may be a risk factor for the development of chronic airflow obstruction. We evaluated this hypothesis in a cohort of 378 underground coal miners and working nonminers. Methacholine testing was performed at the beginning and end of a 5-yr study period. Spirometry was repeated at 6-mo intervals and individual 5-yr FEV1 slopes were calculated by linear regression. Relationships between FEV1 slopes and NSBR were examined using multiple linear regression models, controlling for FEV1 level, smoking, and mining. Increasing NSBR at the initial survey was associated with a somewhat greater rate of subsequent FEV1 decline. Methacholine responders at the final survey had a considerably increased rate of decline during the previous years. Responsiveness status changed over the 5 yr in 22% of the subjects. Both the development and persistence of increased NSBR were strongly associated with higher rates of FEV1 decline. In contrast, FEV1 declines were not accelerated among workers with increased NSBR that reverted to normal. Smoking and mining were both independently associated with FEV1 declines, but did not substantially modify the effect of NSBR. Due to its variability over time, NSBR testing predicts lung function decline only in some individuals, and its value as a prognostic test for chronic airway disorders is limited. Because improvement in bronchial hyperresponsiveness was associated with a reduction in the rate of FEV1 loss, interventions directed at preventing or reducing nonspecific airway hyperresponsiveness should be investigated.