Mining coal in China can be dangerous. However, actually using some coal may be worse.
Domestic use of coal containing high levels of silica could be the cause of higher cancer rates within rural Xuan Wei county, China.
A recent mining disaster in China, which claimed the lives of 108 people, has highlighted the potential dangers of coal. The incident was one of the deadliest tragedies in a series of coal mining accidents within the People's Republic.
While Chinese authorities are currently investigating the matter and working to improve safety practices, it appears that miners aren't the only ones at risk from coal, according to a new study.
Since at least the 1980s, health experts have wondered why non-smoking women in some parts of rural Xuan Wei county, China, die of lung cancer at higher rates than anywhere else in the world -- at rates up to 20 times higher than elsewhere in China.
A new study may have found the cause: domestic use of coal containing high levels of silica, a consequence of volcanic activity during the world's greatest mass extinction 250 million years ago.
In a paper published in Environmental Science and Technology, a research team led by David Large of the University of Nottingham in the United Kingdom took a geological view of the mystery, analyzing the composition of the coal from several sites in Xuan Wei and comparing it with samples from elsewhere in China and the United States.
For years, researchers have attempted to explain this cancer epidemic. Many have suspected polycyclic organic hydrocarbons (PAHs), large organic molecules that form when coal is burned. PAHs are often toxic and suspected to cause cancer.
However, PAH levels alone cannot account for the high incidence of cancer in Xuan Wei.
Coal-burning produces PAHs. Unventilated, indoor heating and cooking stoves, which provide a steady source of smoke in the home, were common throughout China until recently.
The coal used in Xuan Wei had a unique composition, Large found. 'There is masses and masses of silica, and most of that silica is very fine-grained,' he said.