  We argue for a recently observed puzzling multiferroic behavior in s=1/2 1D
chain cuprate LiCu2O2 with edge-shared arrangement of CuO4 plaquettes and
incommensurate spiral spin ordering can be consistently explained if one takes
into account the nonrelativistic exchange-induced electric polarization on the
Cu2+ centers substituting for the positions native for the Cu1+ ions. These
substituent centers are proved to be an effective probe of the spin
incommensurability and magnetic field effects.
