Differences in the biological activity of two PM3.3 components: carbonaceous and silica particles.

In this study we compared the biological reactivity of PM3.3 with those of carbon black (CB) and respirable silica particles, monitored by in vitro hemolytic potential and morphological alterations, in order to evaluate the correlations between the different physico-chemical characteristics of the three types of particulate and their biological effects. Carbon black and silica particles were used as reference environmental particles in order to limit the number of the urban PM variables, which is a mixture highly heterogeneous. Our data suggest that the urban PM3.3 have a similar surface reactivity as CB. In fact, when the percent of hemolysis were plotted against particle surface per volume units, the PM3.3 activity did not differ significantly from that of CB. This observation is in agreement with the SEM morphological evaluations of treated erythrocytes because the more abundant alteration in PM3.3-treated cells was the stomatocytic transformation (main feature of CB-treated red blood cells), followed by echinocytic transformation (observed in silica-treated cells).