Untitled

Abstract

Background: The harmful effects from inhalation of coal dust are well-documented. The prevalence of lung disease varies by mining region and may, in part, be related to regional differences in the bioavailable iron content of the coal. Pyrite (FeS 2 ), a common inorganic component in coal, has been shown to spontaneously form reactive oxygen species (ROS) (i.e., hydrogen peroxide and hydroxyl radicals) and degrade nucleic acids. This raises the question regarding the potential for similar reactivity from coal that contains pyrite. Experiments were performed to specifically evaluate the role of pyrite in coal dust reactivity. Coal samples containing various amounts of FeS 2 were compared for differences in their generation of ROS and degradation of RNA.

Inflammatory stress response in A549 cells as a result of exposure to coal: Evidence for the role of pyrite in coal workers’ pneumoconiosis pathogenesis

“…This study builds upon and extends earlier acellular (Harrington et al, 2012a) (Cohn et al, 2006a) and epidemiological work (Huang et al, 2005) citing pyrite as the major contributing factor in CWP pathogenesis. Specifically, our data shows that epithelial cells challenged with coal containing modest amounts of pyrite (0.52 and 1.15 wt.%) undergo cell death, and the remaining surviving cells show an upregulation of ROS allowing for a dramatically high ISR (798% and 1426% compared to a control, respectively).…”

“…Therefore, one would not necessarily expect a linear increase in ISR with increase pyritic sulfur contents (Finkelman, 1992). The amount of “available” iron, or total iron released in 1.5 mg L −1 RNA solution over a 7 h period, would also contribute to Fenton chemistry (Cohn et al, 2006a). The high available iron content of CSRM number 2684b (a factor of 17.3 greater than of number 2692b and 62% of number 2685b) likely plays a role in the increased ISR, which may be an indication of the accessibility and reactivity of the pyrite within the coal.…”

“…By examining the occurrence of CWP throughout the United States and analyzing coal samples in respective locations, a strong positive correlation is seen between the incidence of CWP and content of bioavailable iron (BAI) in coal (predominately pyrite; correlation coefficient r = 0.94) (Huang et al, 2005). In a separate study, a similarly strong positive correlation is seen between the occurrence of CWP and the pyritic sulfur content of coal (correlation coefficient r = 0.91) (Cohn et al, 2006a). Furthermore, the ability of coal samples with variable pyrite contents to generate reactive oxygen species (ROS) in a phosphate buffered solution was examined in this earlier work.…”

“…Furthermore, the ability of coal samples with variable pyrite contents to generate reactive oxygen species (ROS) in a phosphate buffered solution was examined in this earlier work. It was determined that not only does the amount of hydrogen peroxide increase with increasing pyritic sulfur content, but so does the coal's ability to generate hydroxyl radical (correlation coefficient r = 0.99) (Cohn et al, 2006a). …”

Metal-sulfide mineral ores, Fenton chemistry and disease – Particle induced inflammatory stress response in lung cells

“…To balance charge, trivalent iron is formally present in chalcopyrite, but charge transfer between iron and sulfur gives iron a strong divalent character (Goh et al, 2006; Todd et al, 2003). Furthermore, as with arsenopyrite, chalcopyrite releases ferrous iron into solution, which is important in the context of this study as the release of ferrous iron will allow the Fenton reaction to go forward: $${\mathrm{normalH}}_2{\mathrm{normalO}}_2+{\mathrm{Fe}}^{2+}\left(\mathrm{aq}\right)\to {\mathrm{OH}}^{-}+{}^{\cdot }\mathrm{OH}+{\mathrm{Fe}}^{3+}\left(\mathrm{aq}\right)$$ Pyrite (FeS 2 ), as the most common sulfide mineral on Earth (and a potent reactive oxygen species generator (Cohn et al, 2006; Schoonen et al, 2006; Schoonen et al, 2010)), is often associated in varying abundances with all the ores described above.…”