Density functional theoretical study elucidates two different pathways for metabolic activation of 2,2'-bis(4-hydroxyphenyl) propane (Bisphenol A; BPA) and consequential formation of 4-methyl-2,4-bis(p-hydroxyphenyl)pent-2-ene (M-1) and 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (M-2, the potential environmental estrogen). Selectivity toward M-1(nontoxic)/M-2(toxic) formation can be controlled by varying the polarity of the reaction medium. We also found the reversal of thermodynamic stability for M-1/M-2 in response to the static polarization of the medium. Moreover, stereocontrol of biologically active M-2 with static polarization as the switch (∼0.005 au) might affect the receptor binding. This analysis may be useful in dictating the prevention of the harmful action of BPA and its metabolites.