  The dispersive effects of vacuum polarization on the propagation of a strong
circularly polarized electromagnetic wave through a cold collisional plasma are
studied analytically. It is found that, due to the singular dielectric features
of the plasma, the vacuum effects on the wave propagation in a plasma are
qualitatively different and much larger than those in pure vacuum in the regime
when the frequency of the propagating wave approaches the plasma frequency. A
possible experimental setup to detect these effects in plasma is described.
