Comparative mutagenicity assessment of aerosols in emissions from biofuel combustion

This study was designed to determine the mutagenicity in extracts of aerosols generated from biofuel combustion in household cooking devices commonly used in India. Wood, dung cake and biofuel briquette were used as fuel in various stoves, including both traditional and improved stoves made of mud, fired clay and metal. The combustion aerosols of particle diameter less than 2.5 μm (PM2.5) were collected, and their organic extracts were tested for mutagenicity using the Ames Assay test with TA98 and TA100 strains of Salmonella typhimurium and studies were performed both with and without metabolic activation to account for direct and indirect acting mutagens. The measured mutagenicity emission factors, i.e., number of revertants per kg of fuel burnt, indicate that wood demonstrates significantly lower mutagenicity compared to dung cake and briquette. No significant stove effect was observed across all the fuels studied. The contribution of direct-acting mutagens was found to be greater than 70% in all cases. Such a high relative contribution of direct-acting mutagenicity has not been previously reported for biomass combustion aerosols.