PIXE analysis revealed different levels of inorganic
elements in tobacco leaves when compared with lettuce
leaves (Table 2). The levels of trace elements in lettuce
were obtained in a previous study by our group. All of the
inorganic elements detected were present in much higher
levels in tobacco leaves than in lettuce leaves. This difference
reflects the fact that the two plants are different species.
Studies in humans and animals have demonstrated that
a wide variety of metals act as mutagenic and carcinogenic
agents (Leonard et al., 2004). In general, metal genotoxicity
is caused by indirect mechanisms, a major one of
which involves interference with cellular redox regulation
and the induction of oxidative stress (ROS generation),
which may cause oxidative DNA damage (Beyersmann and
Hartwig, 2008).