  It is pointed out that the meson mixing matrix elements usually considered
responsible for the bulk of the observed few-body charge symmetry breaking are
naturally $q^2$-dependent in QCD. For $\pi^o-\eta$ mixing, using the usual
representation of the pseudoscalar fields, the leading $q^2$ dependence can be
explicitly calculated using chiral perturbation theory to one loop, the result
being a significant decrease in the magnitude of the matrix element in going
from timelike to spacelike values of $q^2$. Since it is the latter range of
$q^2$ which is relevant to NN scattering and the few-body bound state, this
result calls into serious question the standard treatment of few-body charge
symmetry breaking contributions associated with $\pi^o-\eta$ and $\rho -\omega$
mixing.
