MUTAGENICITY ASSESSMENT OF AIRBORNE PARTICLES IN MEXICO-CITY

The Ames's TA98 strain of Salmonella typhimurium with and without mamm alian metabolic activation was used to detect the mutagenic activity o f organic chemicals associated with airborne particles. Two kinds of p articles: total suspended (TSP) and those particles with an aerodynami c diameter of 10 mu m or smaller (PM10) were collected in glass fiber filters using high-volume samplers during the dry season (December 198 9-March 1990) in the Metropolitan Area of Mexico City at five stations of the air quality network belonging to the Ministry of Social Develo pment. Although the highest mass concentrations of particles were obta ined from the Northeastern and Southeastern areas, the largest frequen cy of mutations was found Downtown which indicated that vehicle exhaus t was an important source. Contrary to what was expected, the mutageni c responses were higher for PM10 than for TSP samples. On the other ha nd, the microsome activation increased significantly the mutagenic act ivity of the complex mixture, which hinted at the presence of higher a mounts of indirect (or promutagens) than direct mutagens both for TSP and PM10.