  This talk contains an analysis of quenched chiral perturbation theory and its
consequences. The chiral behavior of a number of quantities such as the pion
mass $m_\pi^2$, the Bernard-Golterman ratios $R$ and $\chi$, the masses of
nucleons, and the kaon B-parameter are examined to see if the singular terms
induced by the additional Goldstone boson,$\eta'$, are visible in present data.
The overall conclusion (different from what I presented at the lattice meeting)
of this analysis is that, with some caveats on the extra terms induced by
$\eta'$ loops, the standard expressions break down when extrapolating the
quenched data with $m_q < m_s/2$ to physical light quarks. I then show that due
to the single and double poles in the quenched $\eta'$, the axial charge of the
proton cannot be calculated using the Adler-Bell-Jackiw anomaly condition. I
conclude with a review of the status of the calculation of light quark masses
from lattice QCD.

High Energy Physics - Lattice