The hazards of tritium--revisited.

Tritium (3H) is the radioactive isotope of hydrogen, with a half-life of 12.3 years. It is created naturally in the atmosphere, and in higher annual rates in nuclear reactors and in nuclear weapon tests. This article surveys the properties of tritium, its biokinetics and its biological effectiveness. The safety levels of tritium have been a subject of dispute for many years, as many scientists consider that its doses and risks, as promulgated by the International Commission on Radiological Protection are, too low and should be at least doubled. Recent reports and evidence of increased cancer risks near nuclear installations that release tritium are discussed; these are of interest in view of new proposals to expand civil nuclear power.