  Lattice QCD studies of hadron-hadron interactions are performed by computing
the energy levels of the system in a finite box. The shifts in energy levels
proportional to inverse powers of the volume are related to scattering
parameters in a model independent way. In addition, there are non-universal
exponentially suppressed corrections that distort this relation. These terms
are proportional to exp(-m_pi L) and become relevant as the chiral limit is
approached. In this paper we report on a one-loop chiral perturbation theory
calculation of the leading exponential corrections in the case of I=2 pi-pi
scattering near threshold.
