A unit of measurement adapted to the evaluation of the effects of low-doseradiation exposure

A clearer understanding by a wider public of the health effects of radioact ive materials arising in the nuclear industry is essential if the public in terest is to served. Clear and continuous information provided to the publi c about radiation dose from industry is inadequate to an intuitive and corr ect understanding of relative risk in part because radiation exposure is ex pressed in units that non-specialists find difficult to comprehend. We prop ose the establishment of a unit of irradiation dose to the individual that is equal to that provided to a human being by the naturally occurring radio activity of human tissue : the "Dari" from the French for "Dose Annuelle du e aux Radiations Internes" annual dose from internal radioactivity. To the extent of 90%, this radiation is due to potassium 40, of mean life 1.3 bill ion years, that was present in the cosmic dust from which the Earth was for med about 4.5 billion years ago. The DARI amounts to less than 10% of the n atural radiation to which the body is subject, arising from external irradi ation from rocks and from cosmic rays. The use of this unit for expressing the individual's radiation dose from an incident or an accident involving r adioactive materials would facilitate a proper judgment of its impact, and would avoid unwarranted concerns.