GAW Report No. 205 - IGAC Project

CHAPTER 2 - AFRICASeveral studies in Nigeria have dealt with the consequences, such as mental developmentin children, of high blood lead concentrations [Ogunsola et al., 1994]. However, recent leadmeasurements in Lagos and Abuja show that atmospheric lead concentration are now between 1 and2 orders of magnitude lower than previous measurements, following the gasoline lead phase out in2006 [Ezeh et al., 2010].Aerosol biological reactivities of human bronchial epithelial cells from in vitro studiesThe fine and ultrafine aerosol fractions are now recognized to induce biological effects dueto their capacity to reach the distal lung, together with specific compositions including transitionmetals and organic compounds [Happo et al., 2008; Seagrave et al., 2006; Huang et al., 2003].Particle toxicity results from their ability to trigger intracellular production of reactive oxygenspecies in epithelial cells and macrophages, the first cells encountered by particles in therespiratory tract. This oxidative stress activates signalling pathways, leading to the release of proinflammatorybiomarkers (IL-8; IL-6, GM-CSF….) [Mitschik et al., 2008]. Such comprehensiveprocesses of particle health effects have been extensively studied in developed countries, leadingto specific regulations [Ramgolam et al., 2009]. Only a few studies have been conducted indeveloping countries, especially in West Africa [Val et al., 2012; Kouassi et al., 2010; Dieme et al.,2012].An example of such results was part of POLCA, with the aim of characterizing atmosphericparticulate pollution and to determine induced toxicity potential of particles in epithelium cells(16HBE) according to their sizes (coarse, fine and ultrafine particles). Three main situations werescrutinized: Bamako during (BK1) and after (BK2) a typical dust event and Dakar (DK) (aerosolchemical specificities given in Figure 9 and in Table 4). PM biological reactivities werecharacterized from measurements of the expression of a panel of biomarkers.Figure 9 - Size speciated chemical aerosol composition in Dakar and in Bamako during (BK1)and after (BK2) a dust event [Val et al., 2013](Also shown in Chapter 7 as Figure 17)39