Bioassay of Extracts of Ambient Particulate Matter

Abstract

Organic extracts from airborne particles collected at various sites in Scandinavia have been tested for mutagenicity in the Ames Salmonella/microsome assay. Extracts from particles in the respirable size fraction (diameter less than 3 R±m) were mutagenic with and without metabolic activation. The mutagenic activity varied from day to day, mainly due to variations in meteorological parameters, especially wind speed and atmospheric stability. A seasonal variation could also be observed, with the highest average values in winter time.Samples collected in urban areas were considerably more mutagenic than samples from background areas. The results suggest that exhaust from motor vehicles are the most important source of mutagenic particles in urban areas.Comparison of roof top samples with street level samples indicated that atmospheric reactions cause transformation of nonpolar compounds in the primary emission to more oxygenated mutagenic compounds. It is, however, not known to which degree this causes an overall increase of the mutagenic activity.The mutagenic activity of emissions from stationary combustion sources have also been studied, and residential heating by burning solid fuels in small combustion units have been shown to be a major contributor to mutagens in the environment.

Consensus report: mutagenicity and carcinogenicity of car exhausts and coal combustion emissions.

“…Further efforts are needed to identify the unknown compounds. Particularly, the polar fraction of urban air particulate seems to contain biological active compounds (13,66) which are not identified.…”

“…The mutagenic activity of organic extracts of ambient particulate matter in Salmonella typhimurium has been reported from several parts of the world. Industrialized and urbanized areas generally contain more mutagenic substances than rural areas although rural areas may be influenced by long-range transport of mutagenic airborne particles (66).…”

“…The contribution from various sources to the mutagenicity of ambient air has been estimated by several investigators (37,66,95). All of these studies suggest that combustion sources in general are important.…”

Polycyclic aromatic hydrocarbons in ambient air particles in the city of Las Palmas de Gran Canaria

“…Because automobile emissions are among the principal sources of mutagenicity in urban atmospheres (Alfheim et al, 1983)-which has aroused especial interest among scientists in both particulate emissions from diesel engines (Clark et al, 1982;Rapaport et al, 1980) and PAH emissions from petrol engines (Löfroth, 1981;Westerholm et al, 1988;Alsberg et al, 1985)-a city area that might be used as a reference in studying such emissions was chosen as vehicles are the only major source of anthropogenic pollution in it. The specific area studied was Bravo Murillo, a downtown street with heavy motor vehicles traffic (80,000 vehicles/day), of which, a high proportion are diesel propelled (taxis, buses and trucks), and the main roadway connecting the downtown and uptown districts.…”

Human Cell Mutagens in Los Angeles Air

“…Butler et al (12) discovered aerosol mutagenicity differences between cities in six different countries. Studies have also found bacterial mutagenicity to vary with season in Scandinavia (13), in the San Francisco Bay area (14), in northwest Italy (15), and in Newark, NJ (16). In our previous work (17), little seasonal variation was seen in the bacterial mutagenic potency (mutagenicity per µg of organic material supplied to the assay) of 1993 fine urban organic aerosol samples from the Los Angeles area; however, definite spatial variation was observed with the highest bacterial mutagen concentrations found in the immediate vicinity of the densest collections of emission sources, leading us to conclude that direct emissions of mutagenic organics from primary emission sources are very important to the bacterial mutagenicity of the ambient aerosol.…”