What is causing the rise in black lung disease?
Study links silica exposure to recent high rates of severe coal workers' pneumoconiosis

Date:
April 12, 2022
Source:
University of Illinois Chicago
Summary:
Silica exposure is a driving force behind rising rates of coal
workers' pneumoconiosis, according to a new study that compared
the pathology and mineralogy of the disease across generations. The
study offers scientific evidence explaining why progressive massive
fibrosis, the most severe form of black lung disease, is occurring
more frequently and among younger coal workers in West Virginia,
Virginia and Kentucky.



FULL STORY ========================================================================== Silica exposure is a driving force behind rising rates of coal workers' pneumoconiosis, according to a new study published by occupational health experts at the University of Illinois Chicago and their collaborators.


==========================================================================
The study is the first to compare the pathology and mineralogy of
the disease, which is commonly called black lung disease, across
generations. It is also the first to offer scientific evidence explaining
why progressive massive fibrosis, the most severe form of black lung
disease, is occurring more frequently and among younger coal workers in
West Virginia, Virginia and Kentucky.

Before 2005, when the increase was first reported, the incidence of
black lung disease had been on the decline since the 70s, when modern
coal dust controls were put in place. Subsequent investigations have
reported that black lung cases have tripled and that tenured miners in
central Appalachia, the epicenter of the disease, have experienced a
tenfold increase in severe black lung disease.

"We've known that silica is highly toxic and exposure contributes to
coal workers' pneumoconiosis, but we haven't known why coal workers
were suddenly experiencing more disease and more severe forms of
it. Regulations have remained in place, minerals in the Earth have not
changed, and there is no evidence suggesting people have become more
vulnerable to coal dust, so the rise in cases among young workers that
started in the late 90s was baffling," said Dr. Robert Cohen, clinical professor of environmental and occupational health sciences and director
of the Mining Education and Research Center at UIC.

To better understand this phenomenon, Cohen and his collaborators
collected lung tissue samples from coal miners with severe black lung
disease. They compared the samples from miners who were born between
1910 and 1930 with those from miners who were born in or after 1930,
historical and "contemporary" coal miners respectively.

The researchers looked at the samples' pathology -- the physical characteristics of the diseased lungs. Tissues that had more than 75%
silicotic nodules, which are round with whirls of pinkish scar tissue,
were classified as having silica-type disease; tissues with fewer
silicotic nodules and a greater number of grey or black-pigmented
nodules were classified as coal-type (less than 25%) or mixed-type
(25%-75%). They also looked for other lesions, like mineral dust-related alveolar proteinosis, which presents as fluid-like material on lung
tissue and is caused by silica exposure.



========================================================================== Advanced analytic techniques like scanning electron microscopy and X-ray spectroscopy were used to measure the chemistry, crystal structure and
physical properties of the mineral particles in the samples.

Cohen and his team found a clear link between silica exposure and severe
black lung disease in contemporary miners:
* Contemporary miners had significantly higher rates of silica-type
disease
compared with their historical counterparts (57% vs. 18%). In
contrast, historical miners had a significantly higher proportion of
both coal-type (50% vs. 17%) and mixed-type (33% vs. 26%) diseases.

* Mineral dust alveolar proteinosis was more common in contemporary
miners
(70% vs. 37%).

* The percentage (26% vs. 18%) and concentration (4.7 vs. 2.6 billion
particles per cubic centimeters) of silica particles were
significantly greater in contemporary miners.

* The concentration of silica particles was significantly greater
(more
than 50%) when silica-type severe black lung, mineral dust
alveolar proteinosis, silicotic nodules or immature silicotic
nodules were present.

"These findings provide the first direct evidence that silica is a
causative agent behind the increasing incidence of progressive massive
fibrosis -- severe black lung disease. This is critical information that
can be used to determine health-protective permissible exposure limits
for coal miners," Cohen said.

He attributes silica-driven resurgence as likely due to changes in mining technology like the mechanized coal extraction devices introduced in
the U.S.

in the 1950s, when miners born in or after 1930 would have begun their
careers.

"Silica is a mineral found in rock and technology that allows for more
mining below and above the coal seam, which is profitable, means more
cutting through rock and more silica exposure," he said.

"Our findings underscore the importance of controlling workplace silica exposure to prevent the disabling and untreatable adverse health effects afflicting U.S. coal miners," Cohen and his co-authors write.



==========================================================================
In 2019, the Mine Safety and Health Administration initiated a request
for information to inform its silica rules, but the standard established
in 1969 remains in effect. The rule permits 100 micrograms per cubic
centimeter for silica exposure. The Occupational Safety and Health Administration, which sets occupational health standards for nearly all
other industries, allows 50 micrograms per cubic centimeter.

The researchers report their findings in the Annals of the American
Thoracic Society article, "Pathology and Mineralogy Demonstrate Respirable Crystalline Silica is a Major Cause of Severe Pneumoconiosis in US Coal Miners." Co-authors of the study are Dr. Leonard Go, Kirsten Almberg
and Cayla Iwaniuk of UIC.

Collaborating institutions include National Jewish Health and the
University of Colorado, the National Institute for Occupational Safety
and Health, the U.S.

Geological Survey, Virginia Tech, West Virginia University, State
University of New York, the University of Calgary and the University of
the Witwatersrand, Johannesburg.

Cecile Rose, Lauren Zell-Baran, Emily Sarver, Heather Lowers, Sidney Clingerman, Diana Richardson, Dr. Jerrold Abraham, Dr. Carlyne Cool,
Dr. Angela Franko, Ann Hubbs, Dr. Jill Murray, Marlene Orandle, Soma
Sanyal, Naseema Vorajee, Dr. Edward Petsonk, Dr. Rafia Zulfikar and
Dr. Francis Green are co- authors from partner institutions.

The research was funded by the Alpha Foundation for the Improvement of
Mining Safety and Health.


========================================================================== Story Source: Materials provided by University_of_Illinois_Chicago. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Robert A Cohen, Cecile S Rose, Leonard H. T. Go, Lauren M
Zell-Baran,
Kirsten S Almberg, Emily A Sarver, Heather A Lowers, Cayla Iwaniuk,
Sidney M Clingerman, Diana L Richardson, Jerrold L Abraham,
Carlyne D Cool, Angela D Franko, Ann F Hubbs, Jill Murray, Marlene
S Orandle, Soma Sanyal, Naseema I Vorajee, Edward L Petsonk,
Rafia Zulfikar, Francis H.

Y. Green. Pathology and Mineralogy Demonstrate Respirable
Crystalline Silica is a Major Cause of Severe Pneumoconiosis in
US Coal Miners.

Annals of the American Thoracic Society, 2022; DOI: 10.1513/
AnnalsATS.202109-1064OC ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220412140943.htm

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