Background: Canonical histones are regulated by stem-loop-binding protein (SLBP) and are expressed during S phase. Results: Arsenic decreases SLBP levels via epigenetic mechanisms, and histone mRNAs acquire a poly(A) tail. Conclusion: Poly(A) tails allow for the presence of canonical histones outside of S phase. Significance: These mechanisms may be involved in arsenic-induced carcinogenesis.