  We investigate the axial vector torsion-spin coupling effects in the
framework of the Poincar\'e gauge theory of gravity with the general Yang-Mills
type Lagrangian. The dynamical equations for the ``electric'' and ``magnetic''
components of the torsion field variable are obtained in the general form and
it is shown that the helicity density and the spin density of the
electromagnetic field appear as the physical sources. The modified Maxwell's
equations for the electromagnetic field are derived, and the electromagnetic
wave propagation under the action of the uniform homogeneous torsion field is
considered. We demonstrate the Faraday effect of rotation of the polarization
for such a wave, and establish the strong bound on the possible cosmic axial
torsion field from the astrophysical data.
