The volcanic eruptions thought responsible for Earth's largest mass extinction which killed more than 70 percent of plants and animals 250 million years ago is still taking lives today. That's the conclusion of a newly released study showing, for the first time, that the high silica content of coal in one region of China appears to be interacting with volatile substances in the coal to cause uncommonly high rates of lung cancer. The study, which helps solve this cancer mystery, appears in ACS' Environmental Science & Technology, a semi-monthly publication.

David Large and his colleagues note that parts of China's Xuan Wei County in Yunnan Province have the world's highest occurence rate of lung cancer in nonsmoking women 20 times higher than the rest of China. Women in the region heat their homes and cook on open coal-burning stoves that are not vented to the outside. Researchers think that indoor emissions from burning coal cause cancer, but are unclear why the lung cancer rates in this region are so much higher than other areas. Earlier studies show a strong link between certain volatile substances, called PAHs, in coal smoke and lung cancer in the region.

The researchers observed that coal used in parts of Xuan Wei County had about 10 times more silica, a suspected carcinogen, than U.S. coal. Silica may work in conjunction with PAHs to make the coal more carcinogenic, they indicate. The researchers also observed that this high-silica coal was formed 250 million years ago, at a time when massive volcanic eruptions worked to deposit silica in the peat that formed Xuan Wei's coal.


Posted by: Justin234    Source

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