Silica−Volatile Interaction and the Geological Cause of the Xuan Wei Lung Cancer Epidemic

Abstract

Parts of Xuan Wei County, Yunnan Province, China have the highest known lung cancer mortality in nonsmoking women. This high mortality displays a clear spatial relationship to the mines producing coal from the uppermost Permian. Geochemical, petrographic, and grainsize analyses were undertaken on a set of coal samples from Xuan Wei. Results demonstrate that the single geochemical property that makes this coal unusual is its high concentration of quartz (13.5 wt %) of which 35-55% occurs as <10 microm grains. We propose the potential for silica-volatile interaction (PSVI) as a new method for assessing the combined influence of silica and volatile organic matter and use this as a basis for re-evaluating existing ecological data. Published lung cancer mortality values are more strongly correlated with PSVI values for Xuan Wei coal than with volatiles or silica alone and the PSVI values measured are distinct from those of other coals. Finally we propose that the localization of this epidemic to Xuan Wei results from enhanced weathering of the local Emeishan basalts as a consequence of geochemical perturbations at the Permo-Triassic Boundary.

Public health and components of particulate matter: The changing assessment of black carbon

“…The findings of Barone-Adesi et al (2012) suggest that the 25-fold difference in lung cancer risks found in the previous study (depending on the mine), also in Xuanwei, might be due to use of anthracite versus bituminous coals. Large et al (2009) find that smoky coals from Xuanwei have high quartz content, and suggest that the lethality of such coals might be due to interactions between PM 10 silica particles and organics.…”

Metalliferous coal deposits in East Asia (Primorye of Russia and South China): A review of geodynamic controls and styles of mineralization

“…Examples indicating such activity include: the frequent occurrence of tonsteins derived from volcanic ashes in many Late Permian coals of southwestern China (Burger et al, 1990Zhou et al, 2000;Dai et al, 2011); the input of syngeneic submarine exhalation to the peat mire (Dai et al, , 2015b; and the high percentages of quartz and chamosite in the Late Permian coals of eastern Yunnan, which are considered to be derived from plume mantlerelated hydrothermal fluids during peat accumulation or at an early stage of diagenesis (Dai and Chou, 2007;Wang et al, 2012). The quartz of syngenetic hydrothermal origin in eastern Yunnan is usually fine to ultra-fine grained, ranging in size from nanometers to less than 20 μm, and may be related to high lung cancer rates in some of the townships in Xuanwei County of eastern Yunnan Large et al, 2009). …”

Quartz in ash, and air in a high lung cancer incidence area in China

“…Most notable has been the finding that smoky coal users are exposed to high levels of polycyclic aromatic hydrocarbons (PAHs), including the known carcinogen benzo[a]pyrene (BaP) 5–9 . However, more recently, exposure to crystalline silica (quartz) has gained increasing attention as a potential contributor 10–15 . This attention is largely derived from several small studies which have identified higher amounts of quartz in samples of smoky than smokeless coal and a positive correlation between quartz content of smoky coal and lung cancer rates in the area.…”