[Genotoxicity of urban air particulate matter]

This paper reviews the genetic toxicology of urban air particulate. Dusts present in the urban environment are composed of a special type of soot, currently mainly emitted by motor vehicles. This soot contains variable quantities of adsorbed highly active genotoxic compounds (polycyclic aromatic hydrocarbons and their nitro derivatives, i.e., nitroarenes). Nitroarenes are among the compounds with the highest genotoxic activity according to the Ames test (genetic point mutation on bacteria), and are particularly abundant in ultrafine particulate matter (< 1.1 microns) emitted by diesel engines, mainly trucks. Diesel emissions have been considered as probable carcinogenic agents for man by the International Agency for Research on Cancer (IARC). Highly mutagenic activity is present in the air of all the cities in the world, and there is increasing concern about possible carcinogenic effects on the general population as a result of exposure to urban particulate matter. Early epidemiological studies on city-dwellers exposed to heavy pollution indicate an excess of lung tumours. Lastly, there is a possible carcinogenic risk for occupationally exposed workers, such as traffic police and those working for city road cleaning services, etc., who are constantly obliged by their jobs to be exposed to polluted city air at work.