It’s commonly held that left and right photons interact with matter in exactly the same way, because electromagnetism “conserves parity”. But we know that P-symmetry, in our world, is generally broken. Even according to the Standard Model, when light propagates through some media, it interacts with electrons, that are subject to the weak force that isn’t parity-conserving. Can any estimate of “practical” chirality of the photon wrt atomic matter be made? Was there any search for anomalous electromagnetic phenomena related to chirality? Such as optical activity in substances whose physics may not be chiral. Examples of substances without any anticipated form of either structural chirality or angular momentum are argon (all natural isotopes are even), 4He, Th 16O2, but substances that are racemic only statistically (in average) can be considered as well.