Investigating photo-driven arsenics' behavior and their glucose metabolite toxicity by the typical metallic oxides in ambient PM2.5.

ABSTRACT

It is essential and challenged to understand the atmospheric arsenic pollution because it is much more complicated than in water and top-soil. Herein the different behavior of arsenic species firstly were discovered within the ambient PM2.5 collected during daytime and nighttime, winter and summer. The diurnal variation of arsenic species in PMs is significantly correlated with the presence of metallic oxides, specifically, ferrous, titanium and zinc oxides, which might play a key role in the process of the photo-oxidation of As(III) to As(V) with the meteorological parameters and regional factors excluded. Subsequently, the photo conversion of arsenite was detected on metal-loaded glass-fiber filters under visible light. The photo-generated superoxide radical was found to be predominantly responsible for the oxidation of As(III). In order to reveal toxicity differences induced by oxidation As(III), HepG2 cells were exposed to various arsenic mixture solution. We found that the antioxidant enzyme activities suppressed with increasing the As(III)/As(V) ratio in total, followed by the accumulation of intracellular ROS level. The glucose consumption and glycogen content also displayed an obvious reduction in insulin-stimulated cells. Compared to the expression levels of IRS-1, AKT and GLUT4, GLUT2 might be more vulnerable to arsenic exposure and lead to the abnormalities of glucose metabolism in HepG2 cells. Taken together, these findings clarify that the health risk posed by inhalation exposure to As-pollution air might be alleviated owing to the photo-driven conversion in presence of metal oxides.