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Buffering capacity of coal and its acid-soluble Fe2+ content: possible role in coal workers' pneumoconiosis.

Authors
Huang-X; Fournier-J; Koenig-K; Chen-LC
Source
Chem Res Toxicol 1998 Jul; 11(7):722-729
NIOSHTIC No.
20030557
Abstract
Epidemiological studies have shown that the prevalence of coal workers' pneumoconiosis (CWP) differed remarkably between different coal mine regions despite comparable exposures to respirable dust. In the United States, CWP was found to be most common in Pennsylvania coal miners and least common in miners from Utah. The active component(s) responsible for the regional differences in CWP has not yet been identified. In the present study, we found that coals from Pennsylvania, compared with Utah coals, showed a much lower buffering capacity as determined by the amount of acid consumed in order to reach pH 4.5, which is the pH of the phagolysosomes of macrophages. Moreover, the coals from Pennsylvania released large amounts of Fe2+ in the acidified extract, whereas the coals from Utah released little Fe2+. Using electron spin resonance (ESR), we found that the coals from Pennsylvania, but not from Utah, were effective in oxidizing formate by a radical pathway. Two coals, one from Utah with high buffering capacity and low acid-soluble Fe2+ and the other from Pennsylvania with low buffering capacity and high acid-soluble Fe2+, were then selected for cell treatment. We found that human tracheal epithelial (HTE) cells treated with the coal from Pennsylvania (10 microg/cm2) showed a 36% increase in oxidant formation over the control as detected by dichlorofluorescein assay, whereas the coal from Utah had no effect. An electrophoretic mobility shift assay was used to test the binding affinity of nuclear proteins extracted from the coal-treated HTE cells to an oxidative stress-responsive transcription factor activator protein-1 (AP-1) element. The coal from Pennsylvania with high acid-soluble Fe2+ (1 microg/cm2) activated AP-1 to the same extent as 10 microM H2O2, while the coal from Utah without acid-soluble Fe2+ had no effect. These results support our hypothesis that the prevalence of CWP may be higher in coal workers exposed to coal with high acid-soluble Fe2+ and low buffering capacity than in workers exposed to coal with low acid-soluble Fe2+ and high buffering capacity.
Keywords
Coal-workers-pneumoconiosis; Coal-workers; Coal-mining; Coal-miners; Coal-dust; Epidemiology; Respirable-dust; Dusts; Dust-particles; Dust-exposure; Occupational-exposure; Exposure-levels; Exposure-assessment; Calcium-compounds
Contact
Department of Environmental Medicine, New York University Medical Center, 550 First Avenue, New York, New York 10016, USA
CODEN
CRTOEC
CAS No.
7439-89-6; 1305-78-8; 76-54-0
Publication Date
19980701
Document Type
Journal Article
Email Address
xihuang@charlotte.med.nyu.edu
Funding Amount
82403
Funding Type
Grant
Fiscal Year
1998
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-003253
Issue of Publication
7
ISSN
0893-228X
Source Name
Chemical Research in Toxicology
State
NY
Performing Organization
New York University, New York, New York
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