  We revise existing limits on the D-dimensional Planck scale M_D from the
nonobservation of microscopic black holes produced by high energy cosmic
neutrinos in scenarios with D=4+n large extra dimensions. Previous studies have
neglected the energy radiated in gravitational waves by the multipole moments
of the incoming shock waves. We include the effects of energy loss, as well as
form factors for black hole production and recent null results from cosmic ray
detectors. For n>4, we obtain M_D > 1.0 - 1.4 TeV. These bounds are among the
most stringent and conservative to date.
