  The anomaly cancellation condition of the Standard Model may be unnatural in
theories with extra dimensions as an anomaly of a low-energy 4-dimensional
theory can be canceled by an inflow from a bulk. This inflow may give rise to
an observable effect at low energies. We analyze several physical models in
which this effect exists and estimate constraints on its value, imposed by the
modern experimental data. We show that the effect can be large enough to be
observed even when these constraints are satisfied. Positive result of such an
experiment would be a low-energy signature of the existence of extra
dimensions.
