The geologic conditions that very nearly annihilated life 250 million years ago are still killing people today.
Parts of Xuan Wei County in Yunnan Province in China have the world’s highest known death rates from lung cancer in non-smoking women. For thirty years the region, which uses locally mined coal for domestic cooking and heating, has been the focus of intense scientific research to establish a cause.
Now a team of experts led by The University of Nottingham have discovered that high concentrations of fine grained silica found in the coal which is produced from the uppermost Permian coal seam, correlate directly with lung cancer mortality rates. The results of their two year study, funded by UK Office of Science and Innovation through the Royal Society, have been published in the journal Environmental Science & Technology.
Dr David Large from the Department of Chemical and Environmental Engineering said: “Our work is a major break-through that points to a new research direction and a new way of addressing the problem. Our discovery does not, in itself, solve the problem — that is for future work. However we hope that the interest generated by these results will open doors to new research opportunities. Successful future work depends on being able to build an appropriate interdisciplinary team with fuel scientists, geologists, medics and epidemiologists.”
In Xuan Wei coal is used for domestic cooking and heating filling the air within the home with ash and volatiles. Over the past two decades excellent measures have been taken to improve living standards in Xuan Wei and provide better ventilation in dwellings. However, the lung cancer mortality rate shows no sign of diminishing. In turn, this is hampering development in a region that, like most of China, is dependent on coal as the primary energy resource.
The exceptional lung cancer mortality rate has, for many years, been attributed to high concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) — produced when domestic coal is burnt. But the association between PAH levels in the smoke and cancer mortality is very weak and the team led by The University of Nottingham began the search for other causes.
Dr Large said: “Future work should investigate the interaction of organic compounds and dust particles a topic that is of global significance. For example fine grained silica was recently declared a carcinogen. This was highly controversial as many believe that silica cannot cause cancer.
"Others believe that silica causes cancer when other compounds like aromatic hydrocarbons are involved. Xuan Wei provides an ideal opportunity to understand such an interaction. Another line of research is to use our approach to quantify the risk posed by coals worldwide.
“To reduce the risk to the people in China they need to reduce their exposure to the ash, so any practical way that addresses this would help. The first step would be awareness that the ash is hazardous, then in conjunction with the population consider practical ways of reducing ash exposure.”
The research was carried out in collaboration with the Division of Epidemiology and Public Health, at The University of Nottingham, the Department of Mineralogy at the Natural History Museum in London, the School of Public Health, Chinese University of Hong Kong, the State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing, The University of Texas at Dallas and the Yunnan Institute of Coal Geology Prospection, China.
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