Higher lung cancer risk in eastern China: study

People in eastern China likely have a higher risk of developing lung cancer than those in western China because of extensive burning of biomass fuels in homes and factories, according to a study.

The study, by researchers with Environment Canada's air quality research division and Chinese scientists, based its findings on measured levels of polycyclic aromatic hydrocarbons (PAHs) in different parts of China.

PAHs are cancer-causing chemical compounds that are released into the air when fuels like oil and coal are burned in factories and homes.

Although some Chinese families have switched to cleaner fuels, more than 70 percent of households continue to burn biomass fuels - such as coal, wood and dung - in open stoves in poorly ventilated homes for cooking and heating.

That leads to severe indoor air pollution.

The study, published in the Proceedings of the National Academy of Sciences of the United States of America, said PAH levels were higher in eastern China, particularly in the North China Plain, East Sichuan Basin and part of Guizhou province.

Although these provinces only account for 12 percent of China's land mass, they make up 48 percent of the nation's biomass consumption and 66 percent of industrial-coking coal use, Ma Jianmin and the other researchers wrote.

While noting that there were pockets outside eastern China with high PAH levels, the researchers concluded that "the lung cancer risk in eastern China was higher than in western China."

They said rural dwellers, women and children appeared to be particularly vulnerable to inhaling cancer-causing PAHs.

China's northeastern Shanxi province, a major coal producing area, leads China in PAH emissions because of the presence of thousands of small-scale coke ovens that operate without any kind of restrictions, the researchers said.

By comparison, western China, from Tibet to Inner Mongolia, had far lower levels of PAHs, they added.

China's PAH emission was around 114,000 metric tons in 2004, or 29 percent of the world's total.

The study was released as thousands of scientists and researchers gathered in Cancun, Mexico for a global conference on lung health.

SOURCE: Proceedings of the National Academy of Sciences, online December 7, 2009.