  The cosmological lithium problem -- that theory predicts a primordial
abundance far higher than the observed value -- has resisted decades of
attempts by cosmologists, nuclear physicists, and astronomers alike to root out
systematics. We reconsider this problem in the setting of the Standard Model
extended by gauged baryon minus lepton number, which we spontaneously break by
a scalar with charge $2 N_c N_g$. Cosmic strings from this breaking can support
interactions converting three protons into three positrons, and we argue that
an `electric'-`magnetic' interplay can give this process an amplified,
strong-scale cross-section in an analogue of the Callan-Rubakov effect. We
suggest such cosmic strings have disintegrated $\mathcal{O}(1)$ of the
primordial lithium nuclei, and lay out what is necessary for this scheme to
succeed. To our knowledge this is the first new physics mechanism with
microphysical justification for the abundance of lithium uniquely to be
modified after Big Bang Nucleosynthesis.
