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Chemical reactivity of the carbon-centered free radicals and ferrous iron in coals: role of bioavailable Fe2+ in coal workers pneumoconiosis.

Authors
Huang-X; Zalma-R; Pezerat-H
Source
Free Radic Res 1999 Jun; 30(6):439-451
NIOSHTIC No.
20030045
Abstract
Striking differences in the prevalence of coal workers' pneumoconiosis (CWP) exist between different coal mine regions. The major factors responsible for the observed regional differences in CWP have not yet been identified. In the present study, chemical reactivity of the carbon-centered free radicals in coals and lung tissues, as well as ferrous iron in the coals, were studied by ESR techniques. The ESR spectra clearly demonstrated the presence of at least two types of carbon-centered free radical species, which might respectively attribute to the macromolecular phase and the molecular phase of coal. Grinding produced free radicals in coals. Exposure of freshly ground coal to air for 28 h induced a slight increase of free radicals for most of the coals, and a slight decrease after 4 months' exposure. The lung tissue samples of coal workers deceased of CWP showed similar ESR spectra as coal samples, and these radicals were highly stable in the lung. After incubation of coals with glutathione, hydrogen peroxide, sodium formate or oxygen, the coal sample from the Gardanne mine which has never induced CWP, and thus is the least hazardous coal, showed the most significant change in the carbon-centered free radical concentration. No significant changes were observed among other coals reported to induce CWP. On the other hand, we found that the coals released different amounts of Fe2+ in an acidic medium. Interestingly, the prevalence of CWP correlates positively with the released Fe2+ content in these coals and with the amount of oxygen radicals produced by the interaction of Fe2+ with O2 in the acidified coal filtrates. Our studies indicate that the carbon-centered free radicals may not be biologically relevant to coal dust-induced pneumoconiosis, whereas the acid soluble Fe2+, which may be dissolved in the phagolysosomes of macrophages, can then lead to Fe2+-induced oxidative stress and eventual CWP development.
Keywords
Free-radicals; Coal-workers; Coal-dust; Coal-miners; Acids; Iron-compounds; Respiratory-system-disorders; Pulmonary-system-disorders; Black-lung; Coal-workers-pneumoconiosis
Contact
Department of Environmental Medicine, New York University Medical Center, NY 10016
CODEN
FRARER
Publication Date
19990601
Document Type
Journal Article
Email Address
xihuang@charlotte.med.nyu.edu
Funding Amount
82403
Funding Type
Grant
Fiscal Year
1999
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R03-OH-03253
Issue of Publication
6
ISSN
1071-5762
Source Name
Free Radical Research
State
NY
Performing Organization
New York University, New York, New York
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