Huang X, Zalma R, Pezerat H
Laboratoire de Réactivité de Surface et Structure, Université P. et M. Curie, Paris, France.
Chem Res Toxicol. 1994 May-Jun;7(3):451-7. doi: 10.1021/tx00039a025.
Epidemiological studies have shown that a causal relationship may exist between coal dust exposure and emphysema in coal miners. Emphysema can be considered as one of the human pathologies associated with oxidative stress, resulting from oxidant-induced alpha 1-antitrypsin (alpha 1-AT) inactivation and uncontrolled proteolysis of lung tissue. We have previously reported that certain coal dusts contained hydrated ferrous sulfate (FeSO4) that inactivated alpha 1-AT [Huang et al. (1993) Chem. Res. Toxicol. 6, 452-458]. In the present study, we have shown that the FeSO4 originated from oxidation of pyrite (FeS2), which is a typical contaminant of coal dusts. The relative humidity and microenvironment around individual pyrite particles influence the formation of FeSO4 in the coal. However, the subsequent human exposure to coal dust containing FeSO4 depends on the stability of the formed FeSO4. We found that pH played the most important role in stabilizing the FeSO4, such that a final pH < 4.5 after oxidation of pyrite stabilized FeSO4, whereas at high pH the conversion of reactive Fe2+ to Fe3+ was immediate. Sulfuric acid (H2SO4), which is also produced by the oxidation of pyrite, can lower the pH, but it can also be neutralized by other minerals in coal dusts, such as calcite (CaCO3). The stability of FeSO4 in coal dust can also be influenced by the length of exposure to air. Our studies demonstrated that coal samples differed in their capacity to stabilize FeSO4. This current study strengthens our previous reported hypothesis that emphysema, which occurs irregularly in coal miners, could be directly related to exposure to coal dust containing FeSO4.
流行病学研究表明，煤矿工人接触煤尘与肺气肿之间可能存在因果关系。肺气肿可被视为与氧化应激相关的人类病理之一，它是由氧化剂诱导的α1-抗胰蛋白酶（α1-AT）失活以及肺组织不受控制的蛋白水解所导致的。我们之前曾报道，某些煤尘中含有能使α1-AT失活的水合硫酸亚铁（FeSO4）[Huang等人（1993年），《化学研究毒理学》6卷，452 - 458页]。在本研究中，我们已表明FeSO4源自黄铁矿（FeS2）的氧化，黄铁矿是煤尘的一种典型污染物。单个黄铁矿颗粒周围的相对湿度和微环境会影响煤中FeSO4的形成。然而，随后人类接触含FeSO4的煤尘取决于所形成的FeSO4的稳定性。我们发现pH值在稳定FeSO4方面起着最重要的作用，以至于黄铁矿氧化后最终pH值<4.5时能稳定FeSO4，而在高pH值下，活性Fe2+会立即转化为Fe3+。同样由黄铁矿氧化产生的硫酸（H2SO4）可降低pH值，但它也可被煤尘中的其他矿物质（如方解石（CaCO3））中和。FeSO4在煤尘中的稳定性还会受到暴露于空气中时间长短的影响。我们的研究表明，不同煤样稳定FeSO4的能力存在差异。当前这项研究强化了我们之前报道的假说，即煤矿工人中不规则出现的肺气肿可能与接触含FeSO4的煤尘直接相关。
