Overview: Reactive Oxygen in Biological System

Abstract

The occurrence of free radicals in living systems was discovered nearly half a century ago on the basis of the similarity between the effects of ionizing radiation and aging. A broader understanding of the extent and importance of the formation of oxygen-derived free radicals and nonradical reactive oxygen-containing molecules emerged after the discovery of superoxide dismutase. A free radical is defined as any chemical species capable of independent existence that contains one or more unpaired electrons on the outer orbit. The presence of unpaired electrons causes free radicals to be paramagnetic and usually makes them very reactive. Dr. Grzegorz Bartosz covers ‘‘reactive oxygen species in biological systems’’ by discussing the major routes for generation of reactive oxygen species. The work environment contains a number of chemicals that if inhaled or absorbed by the body pose a potential risk for workers’ health. Interaction between air pollutants and living tissue may cause a disturbance of the oxidative balance of the body. The topic of ‘‘oxidative stress-inducing workplace agents’’ is discussed by Drs. Jolanta Gromadzinska and Wasowicz. They cover a number of chemicals found in the workplace that have been shown to have strong oxidative properties. The role of ‘‘essential elements in oxidative stress’’ is discussed by Drs. Wasowicz, Reszka, Gromadzinska, and Rydzynski. They point out that many of the essential elements are involved in protection against oxidative stress as well as in oxidation-induced programmed cell death. Selenium and zinc are among the essential elements involved in these protective mechanisms. A number of physical agents including ultraviolet radiation, electromagnetic ionizing radiation, ultrasound, and low frequency magnetic fields can