  Torsion appears in a natural way in modern formulations of the gravitational
theories. In this work we study several aspects of the interplay between the
Standard Model and a classical gravitational background with torsion. In
particular we consider the problem of the gauge and gravitational anomalies,
$B$ and $L$ anomalies, the effective action for the torsion and the propagation
of electromagnetic radiation in the presence of torsion.
