"In this study we have shown that coal mine dust exposure is a significant predictor of emphysema severity," said Eileen Kuempel, Ph.D., a senior scientist at NIOSH and lead author of the study.
The findings, which were reported in the August 1 issue of the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine (AJRCCM), highlight a health problem related to a growing industry. In the past 25 years, coal production has nearly doubled worldwide.
Dr. Kuempel and colleagues compared lung autopsy results from 722 individuals, including 616 coal miners from West Virginia and 106 non-miners from West Virginia and Vermont. Those from West Virginia were collected from consecutive autopsies from 1957 and 1973 at the Beckley Southern Appalachian Regional Hospital as part of a black lung study. Those from Vermont were taken from consecutive autopsies performed at the University of Vermont between 1972 and 1978. Age at death, race, miner/non-miner status and smoking history were established where possible, and individual exposure to coal dust was estimated using work history data and job-specific dust exposure estimates.
Pathologists Francis Green, M.D., and Val Vallyathan, Ph.D., two of the coauthors on this study, examined sections of the lungs to determine the presence and extent of emphysema. A smaller subset of the study group had their lung tissue analyzed for dust content. Emphysema was graded for type and severity.
The researchers found that cumulative exposure to respirable coal mine dust was a highly significant predictor of emphysema severity after accounting for cigarette smoking, age at death, and race. Miners tended to be older at death than non-miners due to a higher proportion of accidental or other sudden deaths among the non-miners. Miners also smoked less on average, though differences were nonsignificant. However, emphysema in miners was significantly more severe than in non-miners among both smokers and never-smokers. Unsurprisingly, emphysema was also more severe among smokers than never smokers in both miners and non-miners. Coal mine dust exposure and cigarette smoking had similar, additive effects on emphysema severity in this study.
The lung tissue analysis corroborated these findings; the greater the concentration of coal dust in the lungs, the more severe the emphysema.
While the data were collected on miners who worked in the mines before the enforcement of the federal standard limiting legal coal dust concentrations to 2mg/m3 imposed in 1972, the study does have immediate relevance to current occupational safety standards. Even at the current federal standard, a full working lifetime's exposure would produce a cumulative exposure similar to the levels found in the autopsied miners.
"Based on our findings, exposure to respirable coal mine dust for a full working lifetime at the current 2 mg/m3 standard would increase the emphysema severity index by 99 points on average. This provides additional evidence of the need to reduce dust exposures to 1 mg/m3 or less as NIOSH has recommended." said Dr. Kuempel. "Furthermore, miners in developing countries may be faced with exposure levels in excess of those reported here. Thus, the effects of dust that we report are relevant to current conditions in many countries, including the U.S."
A 99-point increase on the 1000-point emphysema severity index scale is equivalent to an approximately 10 percent increase in diseased lung tissue. Previous studies have shown that a 99-point increase in emphysema severity could mean the difference between "normal" and "abnormal" lung function or the worsening of existing lung function.
Coal mine dust exposure is now generally accepted as a cause of COPD, but this study will provide the basis for improved recognition of dust-induced COPD, its relationship to cigarette smoking, and may enhance efforts at prevention, diagnosis and medical management of occupational dust-related lung diseases, according to Dr. Kuempel.
"Coal employs over 7 million people worldwide, 90 percent of whom are in developing countries. Coal production has almost doubled in the past 25 years," notes Benoit Nemery, M.D., Ph.D., in an editorial in the same issue of the AJRCCM. "The environmental and climatic impacts of burning coal are, quite rightly, a source of concern. However, the direct consequences of extracting coal on the health of millions of coal miners must be an equal concern."
"Improving disease surveillance and awareness among healthcare professionals about the occupational components of COPD including emphysema can increase the effective detection and management of these diseases," said Dr. Kuempel.
Keely Savoie | EurekAlert!
Amputees can learn to control a robotic arm with their minds
28.11.2017 | University of Chicago Medical Center
The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
An interdisciplinary group of researchers interfaced individual bacteria with a computer to build a hybrid bio-digital circuit - Study published in Nature Communications
Scientists at the Institute of Science and Technology Austria (IST Austria) have managed to control the behavior of individual bacteria by connecting them to a...
Physicists in the Laboratory for Attosecond Physics (run jointly by LMU Munich and the Max Planck Institute for Quantum Optics) have developed an attosecond electron microscope that allows them to visualize the dispersion of light in time and space, and observe the motions of electrons in atoms.
The most basic of all physical interactions in nature is that between light and matter. This interaction takes place in attosecond times (i.e. billionths of a...
Transistors based on carbon nanostructures: what sounds like a futuristic dream could be reality in just a few years' time. An international research team working with Empa has now succeeded in producing nanotransistors from graphene ribbons that are only a few atoms wide, as reported in the current issue of the trade journal "Nature Communications."
Graphene ribbons that are only a few atoms wide, so-called graphene nanoribbons, have special electrical properties that make them promising candidates for the...
08.12.2017 | Event News
07.12.2017 | Event News
05.12.2017 | Event News
08.12.2017 | Life Sciences
08.12.2017 | Information Technology
08.12.2017 | Information Technology