Individual exposure level following indoor and outdoor air pollution exposure in Dakar (Senegal).

The consequences of indoor and outdoor air pollution on human health are of great concern nowadays. In this study, we firstly evaluated indoor and outdoor air pollution levels (CO, CO2, NO, NO2, PM10) at an urban site in Dakar city center and at a rural site. Then, the individual exposure levels to selected pollutants and the variations in the levels of biomarkers of exposure were investigated in different groups of persons (bus drivers, traders working along the main roads and housemaids). Benzene exposure levels were higher for housemaids than for bus drivers and traders. High indoor exposure to benzene is probably due to cooking habits (cooking with charcoal), local practices (burning of incense), the use of cleaning products or solvent products which are important emitters of this compound. These results are confirmed by the values of S-PMA, which were higher in housemaids group compared to the others. Urinary 1-HOP levels were significantly higher for urban site housemaids compared to semirural district ones. Moreover, urinary levels of DNA oxidative stress damage (8-OHdG) and inflammatory (interleukin-6 and -8) biomarkers were higher in urban subjects in comparison to rural ones. The air quality measurement campaign showed that the bus interior was more polluted with PM10, CO, CO2 and NO than the market and urban or rural households. However, the interior of households showed higher concentration of VOCs than outdoor sites confirming previous observations of higher indoor individual exposure level to specific classes of pollutants.

Mutagenicity and clastogenicity of native airborne particulate matter samples collected under industrial, urban or rural influence.

Airborne particulate matter has recently been classified by the IARC as carcinogenic to humans (group 1). However, the link between PM chemical composition and its carcinogenicity is still unclear. The aim of the present study was to evaluate and to compare genotoxic potencies of 6 native PM samples collected in spring-summer or autumn-winter, either in industrial, urban or rural area. We evaluated their mutagenicity through Ames test on YG1041, TA98, and TA102 tester strains, and their clastogenicity on human bronchial epithelial BEAS-2B cells using comet assay, γ-H2AX quantification, and micronucleus assay. Ames test results showed a strong positive response, presumably associated with nitro-aromatics content. In addition, at least 2 positive responses were observed out of the 3 genotoxicity assays for each of the 6 samples, demonstrating their clastogenicity. Our data suggest that PM samples collected in autumn-winter season are more genotoxic than those collected in spring-summer, potentially because of higher concentrations of adsorbed organic compounds. Taken together, our results showed the mutagenicity and clastogenicity of native PM2.5 samples from different origins, and bring additional elements to explain the newly recognized carcinogenicity of outdoor air pollution.