Limits on CP -odd four-fermion operators containing the strange quark field

The bounds on the neutron electric dipole moment and {ital T}-odd nucleon-nucleon interaction are used to extract the limits on the effective CP-odd four-fermion operators containing a strange quark field. This completes the study of the dim=5,6 CP-odd operators built from light-quark fields. The limits are very strong and comparable to those obtained previously for operators containing up and down flavors. We also analyze the shift of the axionic vacuum, {theta}{sub eff}, induced by four-fermion operators in the presence of the PQ mechanism and conclude that this gives subleading contributions to CP-odd observables as compared with the direct ones. {copyright} {ital 1999} {ital The American Physical Society}