Seasonal variations in the level of mutagenicity: an assessment of respirable particulate matter in Rio de Janeiro, Brazil

Abstract

Respirable particles (PM2.5) can become associated with organic matter containing several compounds such as polycyclic aromatic hydrocarbons (PAHs). Many PAHs have been identified as cancer-inducing chemicals. The mutagenicity of airborne particles is generally associated with PAHs, but recent reviews show that PAHs may not be the predominant mutagens in atmospheric pollution, and that nitroaromatic compounds, aromatic amines and aromatic ketones, often found in moderately polar or highly polar organic fractions, are potent mutagens. Nitro-polycyclicaromatics (nitro-PAHs) are persistent environmental mutagens and can be found in airborne suspended particles from direct sources such as diesel and gasoline exhausts, or may be products of atmospheric reactions in the presence of NO2 and NO3 radicals. In the present work we compared PAH levels and mutagenicity using gas chromatography spectrometry and the Salmonella/microsome assay on organic extracts of PM2.5 for Salmonella typhimurium strain TA98. The samples were collected in two periods: (I) July to October 2010 and (II) November 2010 to May 2011 at three sites in Rio de Janeiro – (1) low urban traffic at the University campus; (2) heavy