Assessment of oxidative stress induced by atmospheric particulate matter: from acellular and cellular assays to the use of model and experimental organisms.

Oxidative stress is considered one of the major mechanisms by which atmospheric particulate matter (PM) can induce adverse effects on living systems. Recently, the assessment of PM-induced oxidative stress effects has gained importance, and many efforts have been invested in identifying the most suitable techniques for evaluating PM toxicological potential. This paper briefly resumes the current knowledge and criticisms related to the application of the OP and cellular assays and systematically reviews the studies focused on the assessment of PM-induced oxidative stress using model or experimental organisms. Currently, the most widely used techniques are acellular oxidative potential (OP) assays, which allow for a quick and relatively low-cost assessment of the OP of PM; however, their biological representativeness has still to be confirmed. Other popular techniques are based on the exposure of different cell lines, which allows for assessing different biological outcomes; however, they are based on simple systems unable to properly represent the response complexity of a complete biological organism. Another issue related to both OP and cellular assays is that they are mainly applied to the extracts of sampled PM filters, with a possible alteration of the actual oxidizing properties of the sample. Conversely, the use of model or experimental organisms for the assessment of PM-induced oxidative stress is less frequent in the literature, even though this would enable the evaluation of multiple stress response pathways and, in some cases, the prevention of any physicochemical alteration of PM by in situ exposure. In this review, we analyzed available papers focused on the study of oxidative stress effects induced by PM in plant and lower animal model/experimental organisms. In our opinion, increased employment of model and experimental organisms may overcome most of the criticisms shown by conventional methods.