Caractérisation physico-chimique et effets cytotoxiques de particules atmosphériques PM 2,5 de la ville de Dakar (Sénégal)

Abstract

Objective: Air pollution is a major risk factor for human health. Numerous epidemiological studies have clearly established a correlation between exposure to fine particulate matter (PM 2.5) and the occurrence of respiratory diseases, including lung cancer. Our work consisted of collecting particles from the city of Dakar, at two different sites (P 1 and P 2) characterized by heavy automobile traffic. Method: The collection of particles was carried out using a cascade impactor. Physico-chemical characterization of the collected PM was conducted using scanning electron microscopy coupled with X-ray diffraction (particle size), inductively coupled plasma atomic emission spectrometry (inorganic chemicals), gas chromatography coupled with mass spectrometry (PAHs and VOCs), and ionic chromatography (ions). Results: Exposure of A549 cells to increasing concentrations of P 1 and P 2 particles causes a significant decrease in the incorporation of bromodeoxyuridine, and in the activity of mitochondrial dehydrogenase, and an increase in the activity of extracellular lactate dehydrogenase. These cytotoxic tests allowed the determination of the lethal concentrations for P 1 (LC 10 = 5.11 μg/cm 2 and LC 50 = 25.56 μg/cm 2) and P 2 (LC 10 = 5.59 μg/cm 2 and LC 50 = 27.97 μg/cm 2). Conclusion: The most significant toxic effect was observed in cells exposed to the highest concentration of P 1 particles (48 μg/cm 2). The results obtained could be explained by the synergistic deleterious effects caused by the inorganic and organic compounds bound to the PM 2.5, sources of reactive species of oxygen, and potentially toxic. © 2011 Société Française de Toxicologie Analytique.