Mutagenicity profile of atmospheric particulate matter in a small urban center subjected to airborne emission from vehicle traffic and sugar cane burning

Abstract

Atmospheric particulate matter (PM) is genotoxic and recently was classified as carcinogenic to humans by the International Agency for Research on Cancer. PM chemical composition varies depending on source and atmospheric conditions. The Salmonella/microsome assay is the most used mutagenicity test and can identify the major chemical classes responsible for observed mutagenicity. The objective of this work was to characterize the mutagenicity of PM samples from a countryside city, Limeira, Brazil, which is influenced by heavy traffic and sugar cane biomass burning. Six samples of total PM were collected. Air mass backward trajectories were calculated. Organic extracts were assayed using the Salmonella/microsome microsuspension mutagenicity assay using TA98, YG1041, and TA1538, with and without metabolic activation (S9). YG1041 was the most sensitive strain and mutagenicity reached 9,700 revertants per m(3) without metabolic activation. Potency for TA1538 was higher than TA98, indicating that this strain should be considered in air mutagenicity studies. The increased response to YG1041 relative to TA98, and the decreased response with S9, suggests that nitroaromatics are the major contributors. Limeira is among the most mutagenic cities in the world. High mutagenicity in Limeira seems to occur when the air mass from the area of sugarcane production is mixed with air from the region impacted by anthropogenic activities such as traffic. An increase in the formation of nitro-polycyclic aromatic hydrocarbons may result from longer contact time between the aromatic compounds and the atmosphere with high NOx and ozone concentration, although more studies are required to confirm this hypothesis.

Evaluating the mutagenic potential of aerosol organic compounds using informatics-based screening

“…The formation of endoperoxides and epoxides and of other reactive oxygenated organic compounds, such as those in Clusters 7 and 8, was hypothesized by Fu et al (2012) to explain the DNA damage caused by photodegraded aromatic compounds. Moreover, the finding of biogenic SOA components with potential mutagenic properties (Cluster 0 and some compounds in Clusters 7 and 8) is in agreement with the results of Alves et al (2016), showing that the mutagenicity of the aerosol is enhanced when pollution is mixed with emissions in rural areas. The overall picture, however, is that a greater proportion of mutagenic compounds was predicted to occur in the anthropogenic SOA classes than in the biogenic ones (Fig.…”

Comparative mutagenic activity of atmospheric particulate matter from limeira, stockholm, and kyoto

“…Several different protocols of the Salmonella /microsome assay have been used, such as plate incorporation (Sato et al, ; Claxton et al, ; Villalobos‐Pietrini et al, ), pre‐incubation (Azuma et al, ; Matsumoto et al, ; Kawanaka et al, ), and microsuspension (Azuma et al, ; De Martinis et al, ; Claxton et al, ; Ducatti and Vargas, ; Umbuzeiro et al, , ). The microsuspension protocol is in general 5–10 times more sensitive than the plate incorporation protocol, including in the PM mutagenicity assessment (Azuma et al, ; Černá et al, ; Claxton et al, ), and is widely used when there is limited amount of sample available or when the aim of the study is to use several strains and/or test conditions (Kado et al, ; DeMarini et al, ; Alves et al, ; IARC, ).…”

Understanding aerosol formation mechanisms in a subtropical atmosphere impacted by biomass burning and agroindustry

“…Lee et al (2008) suggested that in addition to weak condensation sinks, the presence of organic compounds could be one factor contributing to nighttime nucleation, together with lower temperatures. A possible explanation for the particle nucleation observed here at night is therefore the conversion of (semi) volatile organic compounds to less volatile water-soluble forms by reactions involving ozone or nitrate radicals (Lee et al, 2016;Alves et al, 2016). Brown et al (2006) suggested that an abundance of nitrogen and sulfur oxides in polluted atmospheres could lead to nighttime sulfuric acid production by reactions involving the NO 3 radical and SO 2 .…”