  We show that using the modified form of the Dirac Hamiltonian as suggested by
Bekenstein, does not affect the analysis in [1-4] of QSO data pertaining to a
measurement of alpha variation. We obtain the present time limit on
Bekenstein's parameter, tan^{2}chi =(0.2 \pm 0.7)\times10^{-6}, from the
measurement of the hydrogen 2p fine structure using value of alpha obtained
from different experiments.
