545

or to undertake more than first-aid treatment and sutureof superficial injuries. The English report does notagree with the concept of

" central accident units ". But

certain larger units will be more active than others inteaching and research. These larger units should bestaffed and equipped more generously; and they will, infact, be central accident units in all but name. TheScottish report frankly recommends a three-tier struc-ture with a central accident unit which is responsible forundergraduate and postgraduate teaching and research,and the treatment of specially referred patients withmultiple and complicated injuries, as well as for providinga routine service for the local population. The suggestionthat the consultant in administrative charge should be anorthopaedic surgeon is based on the fact that the over-

whelming majority of injuries involve the limbs andlocomotor system. But if the new accident and emergencyservice is to be a success, each member of the team mustfeel that he or she is part of it and has something tocontribute; they must learn to work together and trusteach other. This requires a new relationship betweenconsultants such as Dr. OSBORN 26 called for last week.Both reports emphasise the need for improved instruc-tion in accident surgery, but both reject the idea ofaccident hospitals and of a pure accident surgeon.The growing epidemic of injury is a challenge to the

hospital service that needs to be met with greaterresolution and greater energy than have yet beenevinced.

26. Osborn, G. R. ibid, Sept. 8, 1962, p. 502.

Annotations

THE UNCERTAIN EFFECTS OF RADIATION

THE second comprehensive report of the UnitedNations scientific committee on the effects of atomicradiation again emphasises the unanswered questions andthe urgent need for research into many aspects of radiationand its biological effects. It repeats the advice to minimiseor avoid entirely all forms of unnecessary radiation

exposure, and declares that the " final cessation of nuclear

tests would benefit present and future generations ofmankind."

On the somatic effects of radiation, the committeeconcluded that no new data had emerged which disprovedthe assumed proportionality between dose and effect thatwas used for estimating risks at low doses. But it was clearthat such a relationship might not hold at doses lower thanthose which had been investigated. It was now more fullyrealised that somatic effects were less likely at low dose-rates than at the high dose-rates employed in manyexperiments. The only justifications for applying to lowdoses relationships observed at higher doses, thereforeassuming that there was no threshold for induction ofmalignancies, were the expediency of the procedure andthe consistency of the assumptions regarding mechanismsin both dose ranges. It was not known whether thisprocedure underrated or overrated the risk. The reportadvocates an intensified search for carcinogenic agents inthe environment other than radiation, and continues:

" Laborious though it may be to make observations on the effectsof low doses on large human populations, such observations will beinvaluable in complementing and confirming extensive animalexperiments. Any large-scale investigation, however, especially inman, requires accurate planning to ensure that there is a reasonablelikelihood of obtaining meaningful results. Both clinical and vitaland health statistical studies of sufficiently large populations living inareas of different radiation background, of the survivors of Hiroshimaand Nagasaki, of persons receiving radiation for medical purposesand of occupationally exposed persons require continued support andprompt reporting."

It is now known that the frequency of radiation-induced mutation is not dependent solely on the accumu-lated dose but is also dependent on rate of delivery. The1958 United Nations report 2 suggested that the repre-1. Report of the United Nations Scientific Committee on the Effects of

Atomic Radiation. General Assembly: Official Records, SeventeenthSession, Supplement no. 16 (A/5216). United Nations, New York,1962. U.N. publications are obtainable from H.M. Stationery Office,P.O. Box 569, London, S.E.1.

2. See Lancet, 1958, ii, 355, 360.

sentative doubling dose for man might well lie between10 and 100 rad, with 30 rad as the most probable value.Recent information from mouse experiments suggestedthat for acute irradiation the probable combined value forboth sexes was somewhat lower than 30 rad but not lessthan 15 rad. For chronic irradiation the most probablevalue was 100 rad or possibly higher.

Tackling a very complex task, the committee have

attempted to assess the comparative risks of hereditaryand somatic effects from the main sources of irradiation.These estimates are necessarily subject to variations bya great many factors not yet precisely defined :

The figures in column 1 are based on the ratio between dosesto the gonads (or the genetically significant dose in medicalirradiation) from the various sources. They therefore comparethe risks that gene mutations will be induced. Column 2 givesthe ratio between mean bone-marrow doses, and thereforeestimates the comparative leukaemia risk. The bone-tumour

figures in column 3 are based on doses to cells lining bonesurfaces. Comparison of risks can only be made separately forhereditary and somatic effects. The estimate for continuedtesting is derived from an assumed yearly injection-rate (1megacurie of 90Sr and 1028 atoms of 14C) into the atmosphere.The largest study of the genetic effects of radiation in

man is still the investigation of the offspring of parentsexposed at Hiroshima and Nagasaki. Continuing examina-tion has detected no significant increase in the frequencyof malformations or early deaths in these children. Butthe progeny of irradiated mothers have consistently showna significant excess of females over males, which couldbe the result of radiation-induced sex-linked mutations.The new United Nations report becomes for the

moment the modern text on radiation and its effects: itwill surely be rewritten before long. The few extracts wehave reproduced illustrate how increasing knowledge has,temporarily at any rate, complicated the situation inseveral ways. And, as the report says, " individualsentences or assessments may be misleading if taken outof their appropriate context." The plainest of the report’smessages is that great caution is still essential before thenew sources of ionising radiation can be allowed to con-tinue unabated in man’s environment. Disquiet on thisscore has become familiar: it should not be discounted forthat reason.