title: Quartz in ash, and air in a high lung cancer incidence area in China.
abstract: Exposure to crystalline silica (quartz) has been implicated as a potential cause of the high lung cancer rates in the neighbouring counties of Xuanwei and Fuyuan, China, where the domestic combustion of locally sourced "smoky" coal (a bituminous coal) is responsible for some of the highest lung cancer rates in the nation, irrespective of gender or smoking status. Previous studies have shown that smoky coal contains approximately twice as much quartz when compared to alternative fuels in the area, although it is unclear how the quartz in coal relates to household air pollution. Samples of ash and fine particulate matter (PM2.5) were collected from 163 households and analysed for quartz content by Fourier transformed infrared spectroscopy (FT-IR). Additionally, air samples from 12 further households, were analysed by scanning electron microscopy (SEM) to evaluate particle structure and silica content. The majority (89%) of household air samples had undetectable quartz levels (<0.2 μg/m3) with no clear differences by fuel-type. SEM analyses indicated that there were higher amounts of silica in the smoke of smoky coal than smokeless coal (0.27 μg/m3vs. 0.03 μg/m3). We also identified fibre-like particles in a higher concentration within the smoke of smoky coal than smokeless coal (5800 fibres/m3vs. 550 fibres/m3). Ash analysis suggested that the bulk of the quartz in smoky coal went on to form part of the ash. These findings indicate that the quartz within smoky coal does not become adequately airborne during the combustion process to cause significant lung cancer risk, instead going on to form part of the ash. The identification of fibre-like particles in air samples is an interesting finding, although the clinical relevance of this finding remains unclear.
authors.affiliation: Institute for Risk Assessment Sciences, Division of Environmental Epidemiology, Utrecht University, Utrecht, The Netherlands. Electronic address: g.s.downward@uu.nl.
authors.forename: George S
authors.initials: GS
authors.lastname: Downward
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Hu
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD, USA.
authors.forename: Nat
authors.initials: N
authors.lastname: Rothman
authors.affiliation: Institute for Risk Assessment Sciences, Division of Environmental Epidemiology, Utrecht University, Utrecht, The Netherlands.
authors.forename: Boris
authors.initials: B
authors.lastname: Reiss
authors.affiliation: Netherlands Organization for Applied Research, TNO, Utrecht, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Tromp
authors.affiliation: China National Environmental Monitoring Center, Beijing, China.
authors.forename: Guoping
authors.initials: G
authors.lastname: Wu
authors.affiliation: China National Environmental Monitoring Center, Beijing, China.
authors.forename: Fusheng
authors.initials: F
authors.lastname: Wei
authors.affiliation: Hong Kong University, Hong Kong, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xu
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD, USA.
authors.forename: Wei Jie
authors.initials: WJ
authors.lastname: Seow
authors.affiliation: College of Public Health Sciences, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Chapman
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Lan
authors.affiliation: Institute for Risk Assessment Sciences, Division of Environmental Epidemiology, Utrecht University, Utrecht, The Netherlands.
authors.forename: Roel
authors.initials: R
authors.lastname: Vermeulen
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data*; D002681:China / Q000453:epidemiology; D003031:Coal / Q000032:analysis; D060729:Coal Ash / Q000032:analysis* / Q000737:chemistry; D004784:Environmental Monitoring; D006801:Humans; D015994:Incidence; D019570:Inhalation Exposure / Q000706:statistics & numerical data*; D008175:Lung Neoplasms / Q000453:epidemiology*; D052638:Particulate Matter / Q000032:analysis*; D011791:Quartz / Q000032:analysis*; D012906:Smoke / Q000032:analysis; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000393:Air Pollutants; D003031:Coal; D060729:Coal Ash; D052638:Particulate Matter; D012906:Smoke; D011791:Quartz
keywords: Household air pollution; Lung cancer; Quartz; Solid fuels