Interestingly, oxidative damage is not always harmful. At low levels, ROS play essential roles in cellular signaling and defense mechanisms. For instance, the immune system uses ROS to kill invading pathogens. Moreover, certain cancer therapies, such as radiation and some chemotherapeutic agents, rely on generating ROS to kill cancer cells. The key lies in maintaining a balance where ROS levels are sufficient for normal physiological functions but not so high as to cause pathological damage.
