An International Agency for Research on Cancer (IARC) monograph working group has concluded that indoor emissions from household combustion of coal are carcinogenic in the Group 1 category to humans, and are associated primarily with an increased risk of lung cancer. Dr. Qing Lan of NCI's DCEG was a member of the working group and her research in this area, conducted in Xuan Wei county in China, served as the primary evidence of carcinogenesis.

The working group also concluded that indoor emissions from household combustion of biomass fuel (mostly wood) and from high-temperature frying are probably carcinogenic (Group 2A category) to humans. DCEG scientists contributed to the research leading to these conclusions.

Exposure to environmental carcinogens varies widely around the world, but the use of solid fuels for cooking and heating is most common in low- and medium-resource countries, where about half of the world's population lives. "This provides a warning that exposure to indoor combustion products of coal and other biomass is hazardous, and that steps need to be taken to reduce exposure, such as improving indoor ventilation," said Dr. Lan, who pointed out that many millions of people are at increased risk from such indoor air pollution around the world. In fact, a study by Dr. Lan showed that improved venting of indoor combustion products resulted in a drop in lung cancer rates.

The working group was convened by the IARC Monographs Programme, the cancer research agency of the World Health Organization. A summary of the IARC evaluation was published in the December 2006 issue of The Lancet Oncology.