The coupling of spacetime contorsion with fermions can be non-universal and chiral, leading to a four-fermion interaction which violates parity. We find the contribution of this interaction to the left-right asymmetry for parity violating processes like electron-electron and electron-deuteron scattering and compare with known observations. This provides an estimate of an upper bound on the coupling constants, suggesting that the strength of the “new physics" can be as large as only one order of magnitude smaller than that of weak interactions.