  Cosmic structure formation leads to large-scale shocked baryonic flows which
are expected to produce a cosmological population of structure-formation cosmic
rays (SFCRs). Interactions between SFCRs and ambient baryons will produce
lithium isotopes via \alpha+\alpha \to ^{6,7}Li. This pre-Galactic (but
non-primordial) lithium should contribute to the primordial 7Li measured in
halo stars and must be subtracted in order to arrive to the true observed
primordial lithium abundance. In this paper we point out that the recent halo
star 6Li measurements can be used to place a strong constraint to the level of
such contamination, because the exclusive astrophysical production of 6Li is
from cosmic-ray interactions. We find that the putative 6Li plateau, if due to
pre-Galactic cosmic-ray interactions, implies that SFCR-produced lithium
represents Li_{SFCR}/Li_{plateau}\approx 15% of the observed elemental Li
plateau. Taking the remaining plateau Li to be cosmological 7Li, we find a
revised (and slightly worsened) discrepancy between the Li observations and Big
Bang Nucleosynthesis predictions by a factor of ^7Li_{BBN}/^7Li_{plateau}
\approx 3.7. Moreover, SFCRs would also contribute to the extragalactic
gamma-ray background (EGRB) through neutral pion production. This gamma-ray
production is tightly related to the amount of lithium produced by the same
cosmic rays; the 6Li plateau limits the pre-Galactic (high-redshift) SFCR
contribution to be at the level of I_{\pi_{\gamma}SFCR}/I_{EGRB} < 5% of the
currently observed EGRB.
