Oxygen: our major carcinogen?

Evidence has accumulated implicating that atmospheric oxygen can be considered as an important environmental mutagen, whose action can be potentiated by a variety of environmental factors. Under normal conditions oxygen genotoxicity is largely prevented by a cellular antioxygenic defense system, which must be extremely efficient, but might not be entirely safe. A better understanding of this defense system may help to suggest how the incidence of carcinogenesis can be minimized.