  We consider the impact of combining precision spectroscopic measurements made
in atomic hydrogen with similar measurements made in atomic deuterium on the
search for physics beyond the Standard Model. Specifically we consider the wide
class of models that can be described by an effective Yukawa-type interaction
between the nucleus and the electron. We find that it is possible to set bounds
on new light-mass bosons that are orders of magnitude more sensitive than those
set using a single isotope only, provided the interaction couples differently
to the deuteron and proton. Further enhancements of these bounds by an order of
magnitude or more would be made possible by extending the current measurements
of the isotope shift of the 1s$_{1/2}$-2s$_{1/2}$ transition frequency to that
of a transition between the 2s$_{1/2}$ state and a Rydberg s-state.
