Yes, potency is critical. The endocrine system distinguishes high-potency hormones that convey vital biological signals from other chemicals occurring naturally in the body that interact with it inconsequentially due to their low potency.The endocrine system also responds to high potency chemicals which can alter its functional state through strong interactions that mimic or interfere with hormone action. It does not respond to low potency chemicals, which interact too weakly to alter its functional state.