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SIO? 555 '' g ^ 

DEC 3 1979 

RADIATION PROTECTION 

ICRP PUBLICATION 26 

Recommendations ofthe 

International Commission on 

Radiological Protection 

(ADOPTED JANUARY 17, 1977) 

J PUBLISHED FOR 

The International Commission on Radiological Protection 

BY 

PERGAMON PRESS 

OXFORD : NEW YORK : FRANKFURT 
P.3 

Annals of the ICR 

Published on behalf of the International Commission 

on Radiological Protection 

U. S. NUCLEAR RI 

LIBRARY 

WASHINGTON, Dj-C 

STOP 555 

DEC 3 1979 

Editor: F. D. SOWBY ICRP. Sutton, Surrey 

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Scientific Secretary: Dr. F. D. Sowby, ICRP. Clifton Avenue, Sutton. Surrey SM2 5PU. England 

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Intei 

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The Intern; 

oxr 
RADIATION PROTECTION 

P.4 

ICRP PUBLICATION 26 

Recommendations ofthe 

International Commission on 

Radiological Protection 

(ADOPTED JANUARY 17, 1977) 

PUBLISHED FOR 

The International Commission on Radiological Protection 

A. Introduction 

B. Objectives of Radiatior 

C. Basic Concepts 

Detriment 

Dose equivalent 

Collective dose eqi 

Dose-equivalent cc 

Committed dose ec 

D. Radiobiological Consid 

Dose-response relath 

Implications from as; 

Significant volume. 

Rate of dose accun 

Tissues at risk 

Gonads 

Red bone marrow 

Bone 

Lung 

Pulmonary lymp 

Thyroid 

Breast 

Risk of cancer in al, 

Total stochastic risl 

Lens 

Skin 

Children andfoetui 

Tissues of low sensi 

Other effects 

h. The System of Dose Lim 

The bases for decidi 

Dose-equivalent lm 
P.5 

CONTENTS 

fthe 

non on 

tion 

A. Introduction 

deal Protection 

3. Objectives of Radiation Protection 

C. Basic Concepts 

Detriment 

Dose equivalent 

Collective dose equivalent 

Dose-equivalent commitment 

Committed dose equivalent 

D. Radiobiological Considerations 

Dose-response relationships 

Implications from assumptions about dose-response relationships 

Significant volumes and areas 

Rateofdose.accumulation 

Tissues at risk 

Gonads 

Red bone marrow 

Bone 

Lung 

Pulmonary lymphoid tissue 

Thyroid 

Breast 

Risk of cancer in all other tissues 

Total stochastic risk from uniform whole body irradiation 

Lens 

Skin 

Children andfoetuses 

Tissues of low sensitivity 

Other effects 

Paragraph Number 

1 

6 

55 

.15 

17 

22 

25 

26 

27 

27 

.31 

32 

.35 

36 

40 

44 

47 

49 

•52 

55 

51 

.58 

•60 

61 

63 

65 

66 

67 

E. The System of Dose Limitation 

The bases for deciding what is reasonably achievable in dose reduction 

Dose-equivalent limits--generai 

68 

72 

77 
P.6 

IV RECOMMENDATIONS OF THE ICRP 

Natural radiation and dose-equivalent limits 

Medical exposure of patients and dose-equivalent limits 

Implications for non-stochastic effects 

Dose-equivalent limits for workers 

Recommended dose-equivalent limits 

Planned special exposures 

Occupational exposure of women of reproductive capacity 

Occupational exposure of pregnant women 

Dose-equivalent limits for individual members of the public 

Exposure of populations 

A ccidents and emergencies 

F. General Principles of Operational Radiation Protection 

Introduction 

Protection standards 

Limits 

Reference levels 

Operational optimization 

G. Application to the Different Types of Exposure 

Occupational exposure 

Conditions of work 

Provisions for restricting exposure 

Monitoring of exposure 

The use of protection standards to interpret monitoring results 

Medical surveillance 

Intervention in abnormal situations 

Medical exposure 

Examinations or treatments directly associated with illness 

Systematic examinations 

Examinations for occupational, medico-legal or insurance purposes 

Medical research 

The optimization of exposure 

Professional training 

Other exposures 

The assessment of exposure 

The restriction of exposure 

The release of radioactive materials into the environment 

Direct external exposure from sources used for industrial, 

medical or scientific purposes 

87 

91 

94 

96 

103 

113 

115 

116 

117 

129 

113 

136 

136 

144 

145 

149 

153 

160 

160 

161 

167 

173 

175 

184 

188 

195 

197 

200 

202 

203 

205 

208 

210 

212 

220 

220 

228 

Ths use of prod 

Practices raisin,: 

Tice use of rad ic 

Monimrmg of exp 

Monitoring in n 

Mwzitoring in a 

Intervention 

Appendix 

Rula.governing tl 

Membership 

Method of work 

Relationships with 

Financial support 

Publications of the Co; 

Index 
P.7 

tp 

'.its 

capacity 

public 

?nng results 

llness 

-ance purposes 

• i.< -fi*. . 

nmenL ,'

 ! 

is trial, •- : ''. 

• • '• * ' -

i 

( 

87 * 

91 

94 

96 

103 j 

113 / 

115 ^ 

116 

117 

129 j 

113 I 

136 / 

136 * 

144 l 

145 ( 

149 j 

153 / 

160 

160 

161 

167 

173 

175 

184 

188 

195 

197 

200 / 

202 / 

203 ] 

205 / 

208 1 

210 S 

212 / 

220 / 

220 

228 / 

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^ 

1 

1 

' RECOMMENDATIONS OF THE ICRP 

* 1

 The use of products widely distributed to the public 

Practices raising the level of exposure to natural background 

j The use of radiation sources in teaching 

Monitoring of exposure 

' Monitoring in normal conditions 

Monitoring in abnormal circumstances 

Intervention 

Appendix ^ 

Rules governing the selection and work ofthe Commission 

Membership 

Method of work 

Relationships with other bodies 

i Financial support 

Publications of the Commission 

Index 

f 

| 

| 

\ 

^^^Uljro^g^ ^ 

LHPEMB1 

•BpKSpsg 

WamWrn^M^m 

mmmmmmmmW^WliV'r^^-

V 

229 

235 

237 

238 

238 

241 

242 

Page 

45 

45 

46 

47 

47 

47 

49 

51 
';' * "'3 3 y >' *v* \ 

i y »(,;'!! f jU4 "0 '»'..•''»''' 84JH5!

6

«' " MSy0;^y,9 r y y u , 4 

'«'»»•'„• '"HM 1 '5 i , *v.* i 

* 't* 

* 

P.8 

A. INTRODUCTION 

(1) The International Commission on 

Radiological Protection has been functioning 

since 1928, when it was established by the 

Second International Congress of Radiology. 

It assumed its present organizational form in 

1950 in order to cover more effectively the 

rapidly expanding field of radiation protection. As one of the commissions established 

by the International Congress of Radiology, 

ICRP has continued its close relationship with 

succeeding Congresses, and it has also been 

looked to as the appropriate body to give 

general guidance on the more widespread use 

of radiation sources caused by the rapid 

developments in the field of nuclear energy. 

The Commission continues to maintain its 

traditional contact with medical radiology 

and the medical profession generally, and it 

also recognizes its responsibility to other professional groups and its obligation to provide 

guidance within the field of radiation protection as a whole. Details of the Commission's 

rules, membership and relationships with 

other bodies are to be found in the appendix to 

this report. 

(2) The first recommendations of the ICRP 

were published in T928, and further reports 

were issued in 1931, 1934 arid 1937. Following 

the Commission's reorganization in 1950, 

basic recommendations were issued in 1951, 

1955 and 1959. A list of these and other 

recommendations of ICRP is given in the 

appendix to this report. 

(3) In 1966 the Commission published its 

recommendations (ICRP Publication 9) 

which had been adopted in 1965; they were 

amended in 1969 arid 1971. During the last 

decade new information has emerged which 

has necessitatedareview of theCommission's 

basic recommendations; the present report 

results from the examination of such new 

information by the Commission and its committees and task groups. The recommendations made in this report supersede the former 

basic recommendations published by the 

Commission, but not necessarily those of its 

committees* Although this publication comprises a comprehensive review of its recommendations, references are made in it to other 

reports of ICRP committees and task groups, 

in which more detailed discussion of various 

points may be found. 

(4) As in its previous recommendations, the 

Commission deals in this report with ionizing 

radiations only. Although the Commission 

recognizes that adequate control should be 

established over a number of sources of nonionizing radiations, it continues to consider 

that this is a subject that lies outside its field of 

work. 

(5) The Commission wishes to reiterate that 

its policy is to consider the fundamental 

principles.upon which appropriate radiation 

protection measures can be based. Because of 

the differing conditions that apply in various 

countries, detailed guidance on the application of its recommendations, either in regulations or in codes of practice, should be 

elaborated by the various international and 

national bodies that are familiar with what is 

best for their needs. The Commission recognizes that the individual experts responsible 

for putting radiation protection into practice 

need guidance that is sufficiently flexible to 

allow for national, regional or other variation. 

For this reason the Commission's recommendations are intended to provide an appropriate degree of flexibility. Because of this, 

•The status of the various committee publications is shown in the appendix to this report. 
P.9 

RECOMMENDATIONS OF THE ICRP 

the form in which the recommendations are 

worded will not necessarily be suitable, and 

may often be inappropriate, for direct assimilation into regulations or codes of practice. 

General guidance on the application of the 

Commission's recommendations is given in 

sections F and G. 

B. OBJECTIVES OF RADIATION PROTECTION 

(6) Radiation protection is concerned with 

the protection of individuals, their progeny 

and mankind as a whole, while still allowing 

necessary activities from which radiation 

exposure might result. The detrimental 

effects against which protection is required 

are known as somatic and hereditary; radiation effects are called "somatic" if they 

become manifest in the exposed individual 

himself, and "hereditary" if they affect his 

descendants. 

(7) "Stochastic" effects are those for which 

the probability of an effect occurring, rather 

than its severity, is regarded as a function of 

dose, without threshold. "Non-stochastic" 

effects are those for which the severity of the 

effect varies with the dose, and for which a 

threshold may therefore occur. At the dose 

range involved in radiation protection, hereditary effects are regarded as being stochastic. 

Some somatic effects are stochastic; of these, 

carcinogenesis is considered to be the chief 

somatic risk of irradiation at low doses and 

therefore the main problem in radiation 

protection. 

(8) Some non-stochastic somatic effects are 

specific to particular tissues, as in the case of 

cataract ofthe lens, non-malignant damage to 

the skin, cell depletion in the bone-marrow 

causing haematological deficiencies, and 

gonadal cell damage leading to impairment of 

fertility. Other non-stochastic effects may 

arise in the blood-vessels or connective tissue 

elements which are common to most organs 

of the body, and therefore require that, as a 

precautionary measure, a dose-equivalent 

limit should apply for all body tissues, to ensure that non-stochastic effects do not occur 

in any such tissue. For all these changes, the 

severity of the effect depends on the magnitude ofthedose received, and there is likely to 

be a clear threshold of dose below which no 

detrimental effects are seen. 

(9) The aim of radiation protection should 

be to prevent detrimental non-stochastic 

effects and to limit the probability of stochastic effects to levels deemed to be acceptable. 

An additional aim is to ensure that practices 

involving radiation exposure are justified (see 

paragraph 12 and sections E and F). 

(10) The prevention of non-stochastic 

effects would be achieved by setting doseequivalent limits at sufficiently low values so 

that no threshold dose would be reached, even 

following exposure for the whole of a lifetime 

or for the total period of working life. The 

limitation of stochastic effects is achieved by 

keeping all justifiable exposures as low as is 

reasonably achievable, economic and social 

factors being taken into account, subject 

always to the boundary condition that the 

appropriate dose-equivalent limits shall not 

be exceeded (see paragraphs 103-128). 

(11) Most decisions about human activities 

areibased on an implicit form of balancing of 

costs and benefits leading to the conclusion 

that ike conduct of a chosen practice is 

"worthwhile". Less generally, it is also 

recognized that the conduct of the chosen 

practice should be adjusted to maximize the 

benefit *o the individual or to society. In 

radiation protection, it is becoming possible 

to formalize these broad decision-making 

procedures, though not always to quantify 

them. The procedures are 

detail in section E. Howevc 

of these procedures does n 

sufficient protection for th 

therefore necessa-y. for th 

establish dose-equivalent li 

where the benefits and di 

received by the same i 

population. 

(12) For the above reas on; 

recommends a system of d< 

main features of which are a 

(a) no practice shall be i 

introduction produce 

benefit; 

(b) all exposures shall b 

reasonably achievabl 

social factors being ta 

and 

(c) the dose equivalent tc 

not exceed the limits i 

the appropriate circu 

Commission. 

Detriment 

(15) The deleterious sffet 

radiation may be of many \ 

effects on health there may t 

and non-stochastic effects ir 

vidua! and stochastic effeci 

tions. In addition, there m 

effects not associated with h 

need to restrict the use o 

products. 

(16) The Commission h£ 

concept of detriment to idt 

possible to quantify, all 

effects. In general, the detri 

tion is defined as the mathei 

tion" of the harm incurred \ 

to radiation, taking into ace 

probability of each type of c 

•International Commission on 

Report 19, International Commiss: 
m 

1 

ice on the application of the 

recommendations is given in 

ROTECTION 

tochastic effects do not occur 

sue. For all these changes, the 

effect depends on the magnij received, and there is likely to 

;hold of dose below which no 

jets are seen. 

}f radiation protection should 

: detrimental non-stochastic 

mit the probability of stochasvels deemed to be acceptable, 

aim is to ensure that practices 

tion exposure are justified (see 

id sections E and F). 

revention of non-stochastic 

be achieved by setting dosets at sufficiently low values so 

Id dose would be reached, even 

sure for the whole of a lifetime 

I period of working life. The 

ochastic effects is achieved by 

ufiable exposures as low as is 

ievable, economic and social 

taken into account, subject 

boundary condition that the 

se-equivalent limits shall not 

: paragraphs 103-128). 

visions about human activities 

implicit form of balancing of 

fits leading to the conclusion 

tct of a chosen practice is 

Less generally, it is also 

t the conduct of the chosen 

be adjusted to maximize the 

individual or to society. In 

ction, it is becoming possible 

hese broad decision-making 

jugh not always to quantify 

RECOMMENDATIONS OF THE ICRP 

them. The procedures are discussed in more 

detail in section E. However, the application 

of these procedures does not always provide 

sufficient protection for the individual. It is 

therefore necessary, for this reason also, to 

establish dose-equivalent limits in situations 

where the benefits and detriments are not 

received by the same members of the 

population. 

(12) For the above reasons, the Commission 

recommends a system of dose limitation, the 

main features of which are as follows: 

(a) no practice shall be adopted unless its 

introduction produces a positive net 

benefit; 

(b) all exposures shall be kept as low as 

reasonably achievable, economic and 

social factors being taken into account; 

and 

(c) the dose equivalent to individuals shall 

not exceed the limits recommended for 

the appropriate circumstances by the 

Commission. 

(13) In applying these recommendations, it 

must be recognized that many present practices give rise to dose equivalents that will be 

received in the future. These dose-equivalent 

commitments (see paragraph 25) should be 

taken into account so that necessary developments of present or future practice would not 

be liable to result in undue exposure of any 

members of the public. 

(14) Although the principal objective of 

radiation protection is the achievement and 

maintenance of appropriately safe conditions 

for activities involving human exposure, the 

level of safety required for the protection of 

all human individuals is thought likely to be 

adequate to protect other species, although 

not necessarily individual members of those 

species. The Commission therefore believes 

that if man is adequately protected then othei* 

living things are also likely to be sufficiently 

protected. 

C. BASIC CONCEPTS 

Detriment 

(15) The deleterious effects of exposure to 

radiation may be of many kinds. Among the 

effects on health there may be both stochastic 

and non-stochastic effects in the exposed individual and stochastic effects in later generations. In addition, there may be deleterious 

effects not associated with health, such as the 

need to restrict the use of some areas or 

products. 

(16) The Commission has introduced the 

concept of detriment to identify, and where 

possible to quantify, all these deleterious 

effects. In general, the detriment in a population is defined as the mathematical "expectation" of the harm incurred from an exposure 

to radiation, taking into account not only the 

probability of each type of deleterious effect, 

but also the severity of the effect. These 

deleterious effects include both the effects on 

health and other effects. On some occasions it 

is convenient to deal separately with the 

effects, or the potential effects, on health. 

These are then characterized by the concept of 

detriment to health. For effects on health, if 

pit the probability of suffering the effect /, is 

small and the severity of the effect is expressed 

by a weighting factor g„ then the detriment to 

health, G, in a group of P persons is given by 

G=P]TlPigi 

Dose equivalent 

(17) The absorbed dose,* D, is insufficient 

by itself to predict either the severity or the 

•International Commission on Radiation Units and Measurements, Radiation Quantities and Units, ICRU 

Report /9, International Commission on Radiation Units and Measurements, Washington, 1971. 
P.11 

RECOMMENDATIONS OF THE ICRP 

probability of the deleterious effects on health 

resulting from irradiation under unspecified 

conditions. In radiation protection it has been 

found convenient to introduce a further 

quantity that correlates better with the more 

important deleterious effects of exposure to 

radiation, more particularly with the delayed 

stochastic effects. This quantity, called dose 

equivalent, is the absorbed dose weighted by 

the modifying factors Q and TV given in 

paragraphs 18-20. 

(18) The dose equivalent, H, at a point in 

tissue, is given by the equation 

H = DQN 

where D is the absorbed dose, Q is the quality 

factor and N\s the product of all other modifying factors specified by the Commission. 

Such factors might take account, for example, 

of absorbed dose rate and fractionation. At 

present, the Commission has assigned the 

value 1 to N. The special name for the unit of 

dose equivalent is the sievert (Sv) 

lSv = Ukg-'^lOOrem). 

(19) The quality factor, Q, is intended to 

allow for the effect on the detriment of the 

microscopic distribution of absorbed energy. 

It is defined as a function ofthe collision stopping power (Ioo) in water at the point of 

interest. Interpolated values of Q as a 

function of Lm can be obtained from the 

figure, which is based on the values shown in 

the table. 

Lx-Q RELATIONSHIP 

L-c in water 

(keV/fim) 

3.5 (and less) 

7 

23 

53 

175 (and above) 

0 

1 

2 

5 

10 

20 

For a spectrum of radiation, an effective 

value, Q, of Q at the point of interest can be 

calculated.* 

(20) When the distribution of radiation in 

La,, is not known at all points in the volume of 

interest, it is permissible to use approximate 

o 

o 

20 

1 5 -

10 

I I I I II T 1 I I I I I | ~l 1 IIII I 

' ' ' ' IIII I J ' i i i i i i 

IO3 

Collision stopping power in water, keV//im 

FIG. 1. Quality factor as a function of collision stopping power in water. 

•International Commission on .Radiation Units and Measurements, Dose Equivalent, Supplement lo ICRU 

Report 19, International Commission on Radiation Units and Measurements, Washington, 1973. 

values for Q related to th< 

primary radiation. For this 

mission recommends the f 

Q to be used for both ext 

radiation: 

X rays, y rays and electrons 

Neutrons, protons and 

singly-charged particles of i 

greater than one atomic ma 

unknown energy 

a particles and multiply-ch; 

particles (and particlesof u: 

charge), of unknown cnerg; 

In the case of thermalnt 

uniquely defined, and Q rr 

the tables and diagrams wh 

function of neutron em 

Publication 21, fig. 15, gi 

thermal neutrons). 

(21) The recommended \ 

are intended for use only ir. 

tion, and then for compari 

exposure with the limits of c 

for assessing those compor 

that are taken into aecoun 

such limits. The values of C 

selected on the basis of rele\ 

tive biological effectiveness 

account of the fact that th 

limits (see paragraphs 103-

extrapolations from higher 

which deleterious effects in 

ly assessed. These values c 

not necessarily representa 

relative biological effecti 

observed effects, such as st 

animals at low levels of absc 

stochastic effects in man 

doses. It is particularly im 

equivalent should not be i 

likely early consequences o. 

exposures in man. 

Collective dose equivalent 

(22) The relationship b 

and the distribution of dos 

exposed population is no 

single quantity can adequa 
P.12 

ality factor, Q, is intended to 

effect on the detriment of the 

stribution of absorbed energy, 

a function of the collision stopLa,) in water at the point of 

rpolated values of Q as a 

.ai can be obtained from the 

s based on the values shown in 

.X-Q RELATIONSHIP 

Lv in water 

(keV/Mm) 

and less) 

(and above) 

0 

1 

2 

5 

10 

20 

im of radiation, an effective 

) at the point of interest can be 

he distribution of radiation in 

vn at all points in the volume of 

jermissible to use approximate 

T—I IIII I 

/ 

' ' i i i i i i 

IO3 

ter, keV//im 

g power in water. 

ose Equivalent, Supplement to ICRU 

., Washington;.lV73, 

RECOMMENDATIONS OF THE ICRP 

values for Q related to the various types of 

primary radiation. For this purpose the Commission recommends the following values of 

O to be used for both external and internal 

radiation: 

X rays, y rays and electrons 1 

Neutrons, protons and 

singly-charged particles of rest mass 

greater than one atomic mass unit of 

unknown energy 10 

a particles and multiply-charged 

particles (and particles of unknown 

charge), of unknown energy 20 

In the case of thermal^ neutrons the La, is 

uniquely defined, and Q may be takenjrom 

the tables and diagrams which present Q as a 

function of neutron energy -{viz. ICRP 

Publication 21, fig. 13, giving Q = 2.3 for 

thermal neutrons). 

(21) The recommended values of Q and Q 

are intended for use only in radiation protection, and then for comparing actual levels of 

exposure with the limits of dose equivalent, or 

for assessing those components of detriment 

that are taken into account in the setting of 

such limits. The values of Q and Q have been 

selected on the basis of relevant values of relative biological effectiveness but they also take 

account of the fact that the dose-equivalent 

limits (see paragraphs 103-104) are based on 

extrapolations from higher absorbed doses at 

which deleterious effects imman can be directly assessed. These values of Q are therefore 

not necessarily representative of values of 

relative biological effectiveness for other 

observed effects, such as stochastic effects in 

animals at low levels of absorbed dose or nonstochastic effects in man at high absorbed 

doses. It is particularly important that dose 

equivalent should not be used to assess the 

likely early consequences of severe accidental 

exposures in man. 

Collective dose equivalent 

(22) The relationship between detriment 

and the distribution of dose equivalent in an 

exposed population is not simple, and ho 

single quantity can adequately represent the 

distribution for the purpose of assessing detriment. Nevertheless, there are many situations 

in which valuable use can be made of the 

quantity called collective dose equivalent. 

The collective dose equivalent (S) in a population is defined by the expression 

S=ll,H,P, 

where //, is the per caput dose equivalent in 

the whole body or any specified organ or 

tissue of the Pt members of sub group (/') of 

the exposed population. The application of 

this concept is discussed in paragraphs 219, 

221 and 232. 

(23) The collective dose equivalent (Sk) 

from a practice or source (k), is defined by the 

expression 

H: HP(H)dH 

where P{H) dH is the number of individuals 

receiving a dose equivalent in the whole body 

or any specified organ or tissue in the range H 

toH+ dH. It is often not necessary to assess 

the contributions from small values of H 

accurately, provided that an upper estimate 

shows that they would not add significantly to 

the total integral. Ordinarily, the upper range 

of the integration is limited by the relevant 

dose-equivalent limits. A collective dose 

equivalent including contributions from high 

doses is not suitable for assessments of the 

type described in paragraph 24. 

(24) In the definition of the detriment to 

health (paragraph 16), if there is a proportional 

relationship between H and /?, (see paragraphs 

27-30) and if gt is independent of H, then the 

detriment to health, G, is proportional to 

the collective dose equivalent, Sk. The validity 

of this relationship between detriment 

and collective dose equivalent depends on 

the validity of the assumed linearity, with 

no threshold, between risk and dose equivalent. The Commission has stressed that this is 

a cautious assumption, the reliability of which 

has not yet been established, and it is 

conceivable that the proportionality factors 
P.13 

RECOMMENDATIONS OF THE ICRP 

or risk factors (risk per unit dose equivalent) 

could vary with the previously accumulated 

dose equivalent. However, for practices 

resulting in small increments of dose 

equivalent above that corresponding to the 

natural background, the additional detriment 

to health, AC, from a practice (k) must be 

closely proportional to 5*, even though the 

proportionality constant may be unknown. 

Furthermore, approximate proportionality 

would hold in cases where all the individual 

dose equivalents fell within a roughly linear 

region of the dose-response relationship. 

Dose-equivalent commitment 

(25) Further quantities are needed when the 

exposure is extended in time. The doseequivalent commitment, Hc> from a given 

decision or practice, is the infinite time integral of the per caput dose-equivalent rate, 

H(t), in a given organ or tissue for a specified 

population: 

The exposed population is not necessarily 

constant in number. It is also possible to 

define a collective dose-equivalent commitment, which is obtained by integration of the 

collective dose-equivalent rate. 

Committed dose equivalent 

(26) Another quantity used in these recommendations is the "committed dose equivalent", //so, to a given organ or tissue from a 

single intake of radioactive material into the 

body. This quantity, which may be considered 

to be a special case of dose-equivalent commitment, is the dose equivalent that will be 

accumulated over 50 years, representing a 

working life, following the intake: 

f'o + 50y 

H50 = \ H(t)dt 

J 'o 

H ff(t) dt 

where//(0 is the relevant dose-equivalent rate 

and t0 is the time of intake. 

D. RADIOBIOLOGICAL CONSIDERATIONS 

DOSE-RESPONSE RELATIONSHIPS 

(27) The relationship between the dose 

received by an individual and any particular 

biological effect induced by irradiation is a 

complex matter on which much further work 

is needed. For radiation protection purposes 

it is necessary to make certain simplifying 

assumptions. One such basic assumption 

underlying the Commission's recommendations is that, regarding stochastic effects, 

there is, within the range of exposure conditions usually encountered in radiation work, a 

linear relationship without threshold between 

dose and the probability of an effect. The 

simple summation of doses received by a 

tissue or organ as a measure of the total risk, 

and the calculation of the collective dose 

equivalent (see paragraphs 22 and 23), as an 

index of the total detriment to a population, 

are valid only on the basis of this assumption 

and that the severity of each type of effect is 

independent of dose. 

(28) The added risk from a given dose increment will depend on the slope of the doseresponse relationship. If the dose-response 

relationship for stochastic processes is in fact 

highly sigmoid, the risk from low doses could 

be overestimated by making a linear extrapolation from data obtained at high doses. 

There are radiobiological 

ing that the dose-respons 

radiation will generally ir 

increasing dose and dt 

absorbed dose range up 

many effects studied t 

response in this range ca: 

an expression of the form: 

E = aD + 

where E denotes the effc 

" A " and "b" are constr. 

term (bD2) in this express; 

high absorbed doses (gi 

gray) and high absorbed 

order of one gray per r 

linear term (aD) and the sk 

come to predominate as th 

are reduced. Although a 

form has been document 

effects, the relative value-

"a" and "6 " vary from 

another. The extent to wh 

may differ for other si tua 

determined. For huma 

particular, knowledge of • 

tionships is too limited u 

prediction of the shapes 

curves at low doses and lov 

theless, in a few instances r: 

based on results of irra 

populations involving sins 

ofthe order of 0.5 Gy or le 

repeated at intervals of a fe 

such cases it can be reasor 

the frequency per unit absc 

cular harmful effects re< 

exposures is not likely to o 

•Igray(Gy)=Ukg-|(=100ra 

tAt high doses this expression •• 

cell sterilization. This effect is nc 

see paragraph 33.) 
population is not necessarily 

imber. It is also possible to 

tive dose-equivalent commitobtained by integration of the 

equivalent rate. 

se equivalent 

•quantity used in these recomthe "committed dose equivai given organ or tissue from a 

f radioactive material into the 

ntity, which may be considered 

case of dose-equivalent come dose equivalent that will be 

>ver 50 years, representing a 

blowing the intake: 

-i: 

, + 30y 

H(t) dt 

:e relevant dose-equivalent rate 

e of intake. 

KRATIONS 

HIPS 

as a measure of the total risk, 

Iation of the collective dose 

paragraphs 22 and 23), as an 

tal detriment to a population, 

m the basis of this assumption 

verity of each type of effect is 

dose. 

ed risk from a given dose incre-

:nd on the slope of the doseonship. If the dose-response 

r stochastic processes is in fact 

. the risk from low doses could 

ed by making a linear extradata obtained at high doses. 

RECOMMENDATIONS OF THE ICRP 

There are radiobiological grounds for assuming that the dose-response curve for low-LET 

radiation will generally increase in slope with 

increasing dose and dose rate, over the 

absorbed dose range up to a few gray.* For 

many effects studied experimentally, the 

response in this range can be represented by 

an expression of the form: 

E = aD + bD21 

where E denotes the effect, D the dose and 

"a" and "b" are constants. The quadratic 

term (bD2) in this expression predominates at 

high absorbed doses (generally above one 

gray) and high absorbed-dose rates (of the 

order of one gray per min); however, the 

linear term (aD) and the slope that it represents 

come to predominate as the dose and dose rate 

are reduced. Although a relationship of this 

- form has been documented for a variety of 

effects, the relative values of the parameters 

" A" and "b" vary from one observation to 

another. The extent to which the relationship 

may differ for other situations remains to be 

determined. For human populations in 

particular, knowledge of dose-response relationships is too limited to enable confident 

prediction of the shapes and slopes of the 

curves at low doses and low dose rates. Nevertheless, in a few instances risk estimates can be 

based on results of irradiation of human 

populations involving single absorbed doses, 

of the order of 0.5 Gy or less, or to such doses 

repeated at intervals of a few days or more. In 

such cases it can be reasonably assumed that 

the frequency per unit absorbed dose of particular harmful effects resulting from such 

exposures is not likely to overestimate greatly 

the frequency of such effects in the dose range 

of concern in radiation protection, even 

though the latter may be received at much 

lower dose rates. 

(29) In many instances, however, risk 

estimates depend on data derived from 

irradiation involving higher doses delivered at 

high dose rates. In these cases, it is likely that 

the frequency of effects per unit dose will be 

lower following exposure to low doses or to 

doses delivered at low dose rates, and it may 

be appropriate, therefore, to reduce these 

estimates by a factor to allow for the probable 

difference in risk. The risk factors discussed 

later have therefore been chosen as far as 

possible to apply in practice for the purposes 

of radiation protection. 

(30) The use of linear extrapolations, from 

the frequency of effects observed at high 

doses, may suffice to assess an upper limit of 

risk, with which the benefit of a practice, or 

the hazard of an alternative practice—not: 

involving radiation exposure—may be 

compared. However, the more cautious such 

an assumption of linearity is, the more 

important it becomes to recognize that it may 

lead to an overestimate of the radiation risks, 

which in turn could result in the choice of 

alternatives that are more hazardous than 

practices involving radiation exposures. 

Thus, in the choice of alternative practices, 

radiation risk estimates should be used only 

with great caution and with explicit 

recognition of the possibility that the actual 

risk at low doses may be lower than that 

implied by a deliberately cautious assumption 

of proportionality. 

• l gray (Gy) = I Jkg-1 (= 100 rad). 

tAt high doses ihis expression would have to be modified to take account of the decreased tumour risk caused by 

cell sterilization. This effect is not significant at the doses encountered in normal exposure conditions. (However, 

see paragraph 33.) 
RECOMMENDATIONS OF THE ICRP 

P.15 

IMPLICATIONS OF ASSUMPTIONS ABOUT 

DOSE-RESPONSE RELATIONS 

(31) A practical radiation protection 

system needs to be based on certain simplifying assumptions if it is to be applied effectively. The assumptions already made about 

the proportionality between dose and effect 

over the range of doses of concern in 

radiation protection imply certain principles 

that can be applied to important practical 

problems such as those relating to significant 

volumes and areas and the rate at which 

doses may be accumulated. These are discussed in the paragraphs that follow. 

Significant volumes and areas 

(32) From the assumption about the 

proportionality between dose and response 

(see paragraphs 27-30) it would follow that 

for stochastic effects it would be justifiable 

to consider the mean dose* over all cells of 

uniform sensitivity in a particular tissue or 

organ. This use of the mean dose has 

practical advantages in that the significant 

volume can usually be taken as that of the 

organ or tissue under consideration. 

(33) When the irradiation of a tissue is 

non-homogeneous, the use of the mean dose 

over the tissue ceases to be strictly valid if 

doses to individual cells differ more widely 

than the range of doses over which the doseresponse relationship for the tissue can be 

regarded as linear. An example of this may 

be the irradiation of the lung by radioactive 

particulates. However, on the basis of 

theoretical considerations, and of available 

epidemiological evidence, the Commission 

believes that, for late stochastic effects, the 

absorption of a given quantity of radiation 

energy is ordinarily likely to be less effective 

when due to a series of "hot spots" than 

when uniformly distributed, because of the 

effect of high doses in causing the loss of 

reproductive capacity or the death of cells. 

Thus, with particulate radioactive sources 

within a tissue, to assess the risk by assuming 

a homogeneous dose distribution would 

probably overestimate the actual risk. 

Moreover, for non-stochastic effects, the 

limited amount of cell loss that might result 

at moderate dose levels would be most 

unlikely to cause any impairment of organ 

function. 

(34) For exposure of the skin, either to 

external sources or as a result of skin 

contamination, it is not generally appropriate to average the dose equivalent over the 

entire skin. The averaging procedure will 

depend on the circumstances and is discussed 

in more detail in paragraphs 182 and 183. 

Rate of dose accumulation 

(35) The Commission previously recommended that, for occupational exposure, the 

magnitude of a single dose equivalent should 

be limited to one-half of the former annual 

dose-equivalent limit. This practice, which 

was intended to prevent the accumulation of 

more than the annual dose-equivalent limit 

within a short period of time, now seems to 

be unnecessary. The Commission therefore 

believes that it is sufficient to set annual 

dose-equivalent limits and does not 

recommend any further restrictions either on 

the instantaneous rate or on the rate at which 

the dose equivalent may be accumulated, 

except in the case of occupational exposure 

of women of reproductive capacity and 

pregnant women (see paragraphs 115 and 

116). In consequence, the Commission no 

longer recommends the use of the former 

age-related formula. 

'Unless specifically qualified, the term dose equivalent refers to the mean dose equivalent over the entire organ or 

tissue. 

(36) Im its former rec 

Commission stated that. 

one organ of the bod; 

irradiation of one partict 

is likely to be of greatest i 

of the dose it receives, 

radiation or the importan 

damage tiiat results. This 

referred to as the critic 

circumstances, and dose 

individual was determir 

equivalent limit for that t • 

concept of itBce critical org 

did not permit the summ 

according tto the relative r 

the irradiated tissues. Th< 

recommends a proced; 

account of ttfoe total risk 

exposume of all tissue 

paragrapfcs 104,105 and 1 

(37) F«nr the purpo 

protectMHm ik is necessary t 

. of organs amid tissues thr 

sidered toecannse of ther 

radiaitiamn damage, the st 

damage amid tbe extent to \ 

treatalbfte. In this section 

presents an outline of the 

about ttflnesE features for 

radiatiknm protection. 

(38) Ssmmse of the quant 

discussed iron the followir 

clearly age- «nr sex-dependt 

those ffunr ttBae developmen 

or for aSae induction of her 

additiiHm, ttSne trisk factors 

of nialliipnMgBES are reduce 

becaansetrnffttliie long latent; 

the ckwdktsipminent of these 

reasons ttllae total risk fr 

expoKnnne wifll wary somew 

with SEE, aEttbough in h 

from HBDE awanage value fo: 

sexes ase mast considerab! 

purposes tffinerefore, suffi 

>y rasing a sing 
XP 

S ABOUT 

NS 

'.1 doses in causing the loss of 

capacity or the death of cells, 

particulate radioactive sources 

;, to assess the risk by assuming 

ous dose distribution would 

erestimate the actual risk. 

or non-stochastic effects, the 

nt of cell loss that might result 

dose levels would be most 

ause any impairment of organ 

xposure of the skin, either to 

rees or as a result of skin 

n, it is not generally approage the dose equivalent over the 

The averaging procedure will 

e circumstances and is discussed 

.1 in paragraphs 182 and 183. 

? accumulation 

Commission previously recomfor occupational exposure, the 

\a single dose equivalent should 

one-half of the former annual 

;nt limit. This practice, which 

to prevent the accumulation-of 

ie annual dose-equivalent limit 

t period of time, now seems to 

ry. The Commission therefore 

it is sufficient to set annual 

;nt limits and does not 

tny further restrictions either on 

ecus rate or on the rate at which 

iiivalent may be accumulated, 

case of occupational exposure 

of reproductive capacity and 

men (see paragraphs 115 and 

sequence, the Commission no 

amends the use of the former 

)rmula. 

close equivalent over ihe entire organ,or 

RECOMMENDATIONS OF THE ICRP 

TISSUES AT RISK 

(36) In its former recommendations the 

Commission stated that, when more than 

one organ of the body is exposed, the 

irradiation of one particular organ or tissue 

is likely to be of greatest importance because 

of the dose it receives, its sensitivity to 

radiation or the.importanceto health of any 

damage that results. Thistissue or organ was 

referred to as '.the critical one under the 

circumstances, and dose limitation for the 

individual was determined by the doseequivalent limit for that tissue or organ. The 

concept of the critical organ used in this way 

did not permit the summation of detriment 

according to the relative radiosensitivities of 

the irradiated tissues. The Commission now 

recommends a procedure which takes 

account of the total :risk attributable to the 

exposure of all 'tissues irradiated (see 

paragraphs 104,105 and 125). 

(37) For the purposes of radiation 

protection it is necessary to specify a number 

of organs and tissues that have to be considered because of their susceptibility to 

radiation damage, the seriousness of such 

damage and the extent to which this could be 

treatable. In this section the Commission 

presents an outline of the assumptions made 

about these features for the purposes of 

radiation protection. 

(38) Some of the quantitative risk factors 

discussed in the following paragraphs are 

clearly age- or sex-dependent, as for example 

those for the development of breast cancer 

or for the inductionof hereditary defects. In 

addition, the risk factors for the occurrence 

of malignancies are reduced in older persons 

•because of the long latent periods involved in 

the development of these effects. For these 

reasons the total risk from an individual 

exposure will vary somewhat with age and 

with sex, although in fact the variations 

from the average value for all ages and both 

sates are not considerable. For protection 

purposes therefore, ;sufficient accuracy is 

obtained by using a s'ingle dose-equivalent 

limit for each organ or tissue for all workers 

regardless of age or sex. These limits are 

based upon the average risk levels described 

below for the various organs or tissues. The 

same principle applies also for different 

members of the general public. 

(39) The risk factors for different tissues 

are based upon the estimated likelihood of 

inducing fatal malignant disease, nonstochastic changes, or substantial genetic 

defects expressed in liveborn descendants. It 

is recognized that the appropriate basis for 

quantifying detriment should include die 

evaluation of all other forms of hurt and 

suffering that may result from exposure. 

This problem is the subject of a task group 

report being prepared for the Commission. 

It appears likely that the forms of detriment 

mentioned above would be regarded as the 

dominant components of the harm that may 

be caused by radiation, and those on which 

risk factors should most appropriately be 

based. 

Gonads 

(40) Deleterious effects caused by irradiation of the gonads may be of three different 

types: tumour induction, impairment of 

fertility in the irradiated, individual, and 

hereditary effects in descendants. 

(41) Human gonads appear to have a 

relatively low sensitivity to the induction of 

cancer by irradiation, since no carcinogenic 

effects in these organs have yet been 

documented conclusively. 

(42) In the female, impairment of fertility 

varies with age. Induction of menopause, 

with permanent cessation of fertility, could 

result from an absorbed dose of 3 Gy (lowLET radiation) in a woman aged 40, whereas 

the same absorbed dose might cause only 

temporary amenorrhoea in a woman aged 

20. The difference is related to the fact that 

production of new oocytes normally ceases 

in childhood, the number of such cells 

decreasing progessively with age after 
P.17 

10 RECOMMENDATIONS OF THE ICRP 

menarche, as oocytes lost from the ovary 

through ovulation or for other causes are not 

replaced. In the testis, by contrast, the 

supply of spermatozoa is replenished 

continually throughout adult life by proliferation of spermatogonia and other sperm 

precursor cells. Depletion of such cells by 

irradiation can be repaired if enough 

spermatogonia remain intact to repopulate 

the damaged testis. Although the sperm 

count may be depressed temporarily by an 

absorbed dose of 0.25 Gy (low-LET radiation) delivered at a high dose rate, the 

absorbed dose required to cause permanent 

sterility is larger by at least an order of 

magnitude. 

(43) The gonads are the tissues involved in 

the production of radiation-induced gene 

mutations and chromosomal changes leading 

to hereditary defects. Observations, mainly 

on small mammals and lower organisms, have 

provided data on the frequencies of hereditary 

changes resulting from irradiation; observations on man have indicated the frequencies 

of the various naturally-occurring hereditary 

and partially hereditary diseases that might be 

affected. The extents to which these diseases 

would increase with: a given increase in the 

mutation rate havefor the most part not been 

demonstrated directly in any organism. It is 

believed that the frequency of dominant, sexlinked and certain chromosomal diseases 

would increase in direct proportion to dose. 

The increase in the more common "irregularly 

inherited'' diseases would be less, especially in 

the first two generations. Where the whole of 

the body is exposed uniformly, it has been 

estimated for present purposes that the 

hereditary detriment is likely to be less than 

the detriment due to somatic injury in the 

irradiated individuals. The risk of serious 

hereditary ill health within the first two generations following the irradiation of either 

parent is taken to be about IO2 Sv1, and the 

additional damage to later generations to be 

of the same magnitude. The risk factor for 

radiation protection purposes is given in 

paragraph 60. 

Red bone marrow 

(44) The red bone marrow is taken to be the 

tissue mainly involved in the causation of 

radiation-induced leukaemia; other bloodforming tissues are thought to play a minor 

role in leukaemogenesis. Observations on 

humans irradiated for therapeutic purposes 

or on Japanese survivors of nuclear explosions 

indicate that the incidence of radiationinduced leukaemia reaches its peak within a 

few years after irradiation, and returns to preirradiation levels after about 25 years. For 

radiation protection purposes the risk factor 

for leukaemia is taken to be 210*3 Sv-1. 

(45) The haematopoietic cells in adults are 

assumed to be randomly distributed 

throughout the haematopoietic marrow 

within trabecular bone (see ICRP Publication 

11). Therefore, dose equivalent to those cells 

is calculated as the average over the tissue 

which entirely fills the cavities within 

trabecular bone. 

(46) Animal experiments have indicated 

that a protracted absorbed dose of 20 Gy 

(gamma radiation) over a lifetime would net 

impair the haematopoietic function of the red 

bone marrow. In man the impairment cf 

function of the red bone marrow is not 

considered likely to be a limiting effect, provided that occupational non-stochastic dose 

limits are set at the levels recommended in 

paragraph 103. 

Bone 

(47) The radiosensitive cells in bone have 

been identified as the endosteal cells and 

epithelial cells on bone surfaces (see ICR0 

Publication 11). The Commission recommends that, where possible, dose equivalent 

in bone should apply to the endosteal cells and 

cells on bone surfaces, and should be calculated as an average over tissue up to a distance 

of 10^m from the relevant bone surfaces. 

(48) A review by the Commission of the 

radiosensitivity of bone in relation to the 

development of radiation-induced cancer 

indicates that, per unit dose equivalent, iv is 

much less sensitive thar 

marrow, lung ant! Ihyroi 

radiation pnoteccon the r 

cancer is taken to be'5 3 0-1 

Lung 

(49) Cancer of the lung I 

miners exposed to high 

radon and its decay prodi 

difficult to derive a quan 

risk in terms of dose, be 

range in the esti mates that 

dose per unit concentratic 

However, ike epidemi 

makes it possible to set Iii 

concentration of radon dc 

air and the length of time J 

as to ensure an adequate dt 

A more detailed discussion 

be found in the forthcomi 

mittee 2's task group on i 

their daughter products. 

(50) Cancer of the lung t 

to radiation exposure has n 

people who have workec 

materials in particulate for 

ium, even though some of i 

above current limits. As 

paragraph 33, the Commi: 

the hazard of particulate n 

is likely to be less than 

material distributed unif< 

the lung. 

(51) There is evidence thi 

tion can also induce lung c: 

present indication is that 

cancer is about the same as 

opmentof leukaemia; this < 

to be modified when fun 

available on the time-cours 

of lung cancer after irradiat 

protection purposes the ris 

cancer is taken to be 210~3 S^ 

Pulmonary lymphoid tisi 

ular case of importance cont 

of inhaled particles containi 
CRP 

larrow 

ed bone marrow is taken to be the 

ly involved in the causation of 

duced leukaemia; other bloodsues are thought to play a minor 

kaemogenesis. Observations on 

adiated for therapeutic purposes 

ese survivors of nuclear explosions 

at the incidence of radiationkaemia reaches its peak within a 

ter irradiation, and returns to prelevels after about 25 years. For 

rotection purposes the risk factor 

lia is taken to be 2 IO"3 Sv-'. 

haematopoietic cells in adults are 

to be randomly distributed 

the haematopoietic marrow 

;cular bone (see ICRP Publication 

ore, dose equivalent to those cells 

d as the average over the tissue 

irely fills the cavities within 

30ne. 

mal experiments have indicated 

tracted absorbed dose of 20 Gy 

diation) over a lifetime would not 

laematopoietic function of the red 

ow. In man the impairment of 

if the red bone marrow is not 

likely to be a limiting effect, proviKcupational non-stochastic dose 

^et at the levels recommended in 

103. 

radiosensitive cells in bone have 

ified as the endosteal cells and 

ells on bone surfaces (see ICRP 

i 11). The Commission recom-

., where possible, dose equivalent 

uld apply to the endosteal cells and 

ne surfaces, and should be calcuiverage over tissue up to a distance 

am the relevant bone surfaces, 

eview by the Commission of the 

ivity of bone in relation to the 

nt of radiation-induced cancer 

iat, per unit dose equivalent, it is 

RECOMMENDATIONS OF THE ICRP 11 

much less sensitive than breast, red bone 

marrow, lung and thyroid. For purposes of 

adiation protection the risk factor for bone 

cancer is taken to be 5 10-4 Sv1. 

Lung 

(49) Cancer of the lung has been observed in 

miners exposed to high concentrations of 

:adon and its decay products. In miners it is 

difficult to derive a quantitative estimate of 

:isk in terms of dose, because of the great 

range in the estimates that have been made of 

;.!ose per unit concentration of activity in air. 

However, the epidemiological evidence 

makes it possible to set limits combining the 

concentration of radon daughter products in 

i:ir and the length of time spent in that air, so 

as to ensure an adequate degree of protection. 

A more detailed discussion of this subject is to 

be found in the forthcoming report of Committee 2's task group on radon, thoron and 

r

 heir daughter products. 

(50) Cancer of the lung clearly attributable 

to radiation exposure has not been reported in 

people who have worked with radioactive 

materials in particulate form, such as plutonium, even though some of them were exposed 

above current limits. .As already noted in 

paragraph 33, the Commission believes that 

the hazard of particulate material in the lung 

is likely to be less than that of the same 

material distributed uniformly throughout 

the lung. 

(51) There is evidence that external irradiation can also induce lung cancer in man. The 

present indication is that the risk of lung 

cancer is about the same as that for the development of leukaemia; this estimate may need 

to be modified when further data become 

available on the time-course of development 

of lung cancer after irradiation. For radiation 

protection purposes the risk factor for lung 

cancer is taken to be 2 10"3 S v1. 

Pulmonary lymphoid tissue (52) A particular case of importance concerns the retention 

of inhaled particles containing insoluble compounds in bronchopulmonary lymph nodes, 

which comprise about 1% of all lymphoid 

tissue in the body. Their selective irradiation 

can be regarded as corresponding to extremely non-uniform irradiation of the lymphoid 

tissue as a whole and so probably involving a 

lower hazard than if the contained activity 

were uniformly distributed through the total 

mass of lymphoid tissue. For irradiation of 

lymphocytes, however, the non-uniformity is 

less extreme, owing to the normal circulation 

of lymphocytes through the lymph nodes of 

thebody. 

(53) Autopsy data from men who had 

previously inhaled plutonium particulates 

indicate that the mean concentration of 

plutonium as averaged over the total mass of 

all lymphoid tissue is likely to be substantially 

less than the mean concentration in lung 

tissues. Since the lung is regarded as of higher 

sensitivity than the lymphoid tissue, it is to be 

assumed that the irradiation of lung is likely 

to be more limiting than that of lymphoid 

tissue in determining the dose limitation for 

such inhaled insoluble radioactive particulates. 

(54) For the purposes of radiation protection therefore the Commission considers that, 

in adults, it will be satisfactory to consider the 

trachea, bronchi, pulmonary region and 

pulmonary lymph nodes as one composite 

organ of mass 1 kg, to which dose limitation 

for the lung should apply. 

Thyroid 

(55) The cells at risk in the thyroid gland 

appear to be the epithelial cells of the thyroid 

follicles for which the dose calculation should 

be made. In most cases the mean dose to the 

whole gland will be substantially the same as 

the dose to these cells. 

(56) The sensitivity of the thyroid to the 

induction of cancer by radiation appears to be 

higher than that of the red bone marrow to the 

development of leukaemia. However, the 

mortality from these thyroid cancers is much 

lower than for leukaemia, primarily because 
12 RECOMMENDATIONS OF THE ICRP 

of the success in the treatment of thyroid 

cancer and the slow progress of this type of 

tumour. The overall mortality risk factor is 

considered to be about one quarter of that for 

the red bone marrow; for radiation protection 

purposes the risk factor is taken as 5 l.O-4 Sv1. 

Breast 

(57) Data on the development of breast 

cancer, following irradiation of women, 

suggest that, during reproductive life, the 

female breast may be one of the more radiosensitive tissues of the human body. There are 

indications that, under these circumstances, 

the risk factor for breast cancer may be a few 

times higher than that for leukaemia. For 

radiation protection purposes the risk factor 

is taken to be 2.5 10-3,S\•-' (see also paragraph 

38). 

Risk of cancer in all other tissues 

(58) In addition to those tissues discussed 

above, forwhich an approximate estimate has 

been made of the frequency with which 

malignancies are induced by moderate doses 

of radiation, there are other tissues (e.g. 

stomach, lower large intestine, salivary 

glands and probably liver) for which there is 

evidence that radiation is also carcinogenic at 

moderate doses. However, for these tissues no 

estimate can yet be made of the risk factor, 

although it is likely that this is low. There are 

other tissues, such as muscle and adipose 

tissue, for which little evidence has been 

obtained of any tumour induction at 

moderate doses. 

(59) Some estimate can be obtained,.however, of the total of all malignancies induced, 

relative to the risk of leukaemia induced 

under the same conditions of .irradiation. 

From this evidence it appears likely that the 

majority of all induced malignancies arise in 

those tissues from which approximate estimates of risk have been obtained. On this 

basis it is estimated that the combined risk of 

malignancy in all remaining unspecified 

tissues is unlikely to exceed 5 10-3 S v

1

, and it is 

further assumed that no single tissue is 

responsible for more than one-fifth of this 

value. 

Total stochastic risk from uniform whole 

body irradiation 

(60) For the purposes of radiation protection involving individuals, the Commission 

concludes that the mortality risk factor for 

radiation-induced cancers is about 10-2 Sv1, 

as an average for both sexes and all ages. The 

average risk factor for hereditary effects, as 

expressed in the first two generations, would 

be substantially lower than this, when account 

is taken of the proportion of exposures that is 

likely to be genetically significant, and can be 

taken as about 4 10-' Sv1. Both for the 

somatic, and for the hereditary risk factor, 

the estimates will differ somewhat for workers 

and for members of the general public, because of the difference in age structure of the 

two populations. These differences in total 

risk, however, are not sufficiently large to 

warrant the use of separate values for protection purposes in the two cases. However, the 

assessment of the total population detriment 

due to radiation from a given exposure should 

also take account of the total risk of 

hereditary damage that may be expressed in 

all subsequent generations. This risk, per unit 

:dose, is considered to be about twice that 

which is expressed in the first two generations 

only. 

Lens 

(61) When the lens is subjected to protracted 

irradiation over the occupational lifetime 

with high or low-LET radiation it can be 

concluded that a total dose equivalent of 15 Sv 

would be below the threshold for the production of any lens opacification that would 

"interfere with vision. The Commission therefore recommends that for radiation workers 

the annual dose-equivalent limit for the lens 

should be derived from the above dose 

P.19 

equivalent delivered over: 

(see paragraph 

(62) In admit 

anterior epiiSae 

KM). 

s.the«quat 

lum ofthe 

cai region generally'consii 

oftheleusmosi susceptible 

lens opacities. For t'he pu 

protection tfee equator r. 

considered tt© ljie 3 mm be 

the eye. 

Skin 

(63) InoomunarisoBi with 

discussed, sll i is though 

liable todewaiopfatal cane 

However, COST rreticaHly-un 

in the skin unj.y occur aft 

absorbed doses of 30 Gy 

over weeks or months to : 

skin. Therefore, the use . 

limit for expos are over the 

lifetime, should prevent 

such non-stoctiastic chant 

graph 103). 

(64) The thickness ot 

considerably from one pt 

another. The basal cell lay> 

is taken to bt the skin ti: 

Because of undulations in 

and because© vthe finite th 

a range of 5© -100 [tin (or 

appropriate for specifyini 

sensitive layer of most part: 

practice are wot protected I 

therefore exposed directly 

practical dos<: assessment 

recommends the use of a d< 

reasonablente an value. 
.RP 

ikely to exceed 5 IO-3 Sv1, and it is 

jmed that no single tissue is 

for more than one-fifth of this 

•stic risk from uniform whole 

Hon 

he purposes of radiation proteclg individuals, the Commission 

vat the mortality risk factor for 

duced cancers is about IO-2 Sv1, 

5 for both sexes and all ages. The 

factor for hereditary effects, as 

the first two generations, would 

illy lower than this, when account 

ie proportion of exposures that is 

enetically significant, and can be 

>out 4 10-3 Sv'. Both for the 

d for the hereditary risk factor, 

; will differ somewhat for workers 

nbers of the general public, bedifference in age structure of the 

ions. These differences in total 

;r, are not sufficiently large to 

ise of separate values for protecs in the two cases. However, the 

if the total population detriment 

ion from a given exposure should 

iccount of the total risk of 

amage that may be expressed in 

it generations. This risk, per unit 

sidered to be about twice that 

essed in the first two generations 

the lens is subjected to protracted 

>ver the occupational lifetime 

r low-LET radiation it can be 

at a total dose equivalent of 15 Sv 

ow the threshold for the produclens opacification that would 

1 vision. The Commission thereends that for radiation workers 

ose-equivalent limit for the lens 

lerived from the above dose 

RECOMMENDATIONS OF THE ICRP 

equivalent delivered over the working lifetime 

(see paragraph 103). 

(62) In adults the equatorial portion of the 

anterior epithelium of the lens is the anatomical region generally considered to be the part 

of the lens most susceptible to the induction of 

lens opacities. For the purposes of radiation 

protection the equator of the lens can be 

considered to lie 3 mm behind the surface of 

the eye. 

Skin 

(63) In comparison with the tissues already 

discussed, skin is thought to be much less 

liable to develop fatal cancer after irradiation.. 

' i owever, cosmetically-unacceptable changes 

in the skin may occur after irradiation with 

;:osorbed doses of 20 Gy or more, delivered 

over weeks or months to limited portions of 

>kin. Therefore, the use of this value, as a 

limit for exposure over the whole occupational 

lifetime, should prevent the occurrence of 

>uch non-stochastic changes (see also paragraph 103). 

(64) The thickness of the skin varies 

considerably from one part of the body to 

another. The basal cell layer of the epidermis 

is taken to be the skin tissue most at risk. 

Because of undulations in the basal cell layer 

and because of the finite thickness of its cells, 

a range of 50-100 pirn (or 5-10 mg cm-2) is 

appropriate for specifying the depth of the 

sensitive layer of most parts of the skin that in 

practice are not protected by clothing and are 

therefore exposed directly to radiation. For 

practical dose assessment the Commission 

recommends the use of a depth of 70 pm as a 

reasonable mean value. 

23 

Children and foetuses 

(65) Exposure before birth or during child 

hood may interfere with subsequent growth 

and development, depending on factors such 

as dose and age at irradiation. Susceptibility 

to the induction of certain malignancies also 

appears to be higher during the prenatal and 

childhood periods than during adult life. 

Tissues of low sensitivity 

(66) It is now established that theri are 

various tissues in which the development of 

malignancy following irradiation seems to be 

very rare, as evidenced by the fact that 

epidemiological surveys have so far not 

shown excess rates of malignancy in such 

tissues. For these tissues dose limitation is 

based on the possibility of vascular or other 

deleterious changes. There may also be some 

tissues, for example those containing nonnucleated cells, the irradiation of which can 

be ignored for the purposes of radiatiow 

protection. 

Other effects 

(67) Other than the specific effects already 

discussed, there is no good evidence of 

impairment of function of organs and tissues 

at the levels of dose normally encountered in 

radiation work. The evidence for life-shortening from effects other than tumour induction 

is inconclusive and cannot be used quantitatively. Moreover, it seems unlikely that any 

major hazard from irradiation at recommended levels has been overlooked, as Lidged 

by the evidence from heavily irradiated 

populations, observed for periods up to 30 

years. 
P.21 

:

 il! ': 

14 RECOMMENDATIONS OF THE ICRP 

E. THE SYSTEM OF DOSE LIMITATION 

(68) In order to achieve the objectives listed 

in paragraph 12, the Commission recommends a system of dose limitation, the main 

purposes of which are to ensure that no source 

of exposure is unjustified in relation to its 

benefits or those of any available alternative, 

that any necessary exposures are kept as low 

as is reasonably achievable, and that the dose 

equivalents received do not exceed certain 

specified limits and that allowance is made for 

future development. These points are 

expanded further in the following paragraphs. 

(69) Ideally the acceptability of a proposed 

operation or practice involving exposure to 

radiation should be determined by costbenefit analysis, the purpose of which is to 

ensure that the total detriment should be 

appropriately small in relation to the benefit 

resulting from the introduction of the 

proposed activity. Comparisons between 

practices should be made after the application 

of the procedure of optimization (see 

paragraphs 72-76). The choice between 

practices will depend on many factors, only 

some of which will be associated with radiation protection. For "this reason, the comparison of practices is not discussed further in this 

report. Optimization, on the other hand, 

should be a major part of practical radiation 

protection; it is discussed in more detail in the 

following paragraphs. 

(70) In cost-benefit analysis the benefits are 

taken to include all the benefits accruing to 

society, and not just those that will be received 

by particular groups or individuals. In certain 

circumstances benefits can be quantified, but, 

when they contribute to the satisfaction of 

human desires, such quantification may 

prove difficult. Costs are considered as 

comprising the sum total of all negative 

aspects of an operation, including monetary 

costs and any damage to human health or to 

the environment. Since the distribution 

through the population of these benefits and 

costs will not be the same, this broad process 

of balancing would, however, be legitimate 

only if the detriment to each individual does 

not exceed an acceptable level. In exercising 

this process in relation to ionizing radiation, 

the individual limitation of detriment would 

be achieved by compliance with the Commission's dose-equivalent limits. 

(71) It may thus be necessary to make 

subjective value judgments in order to compare the relative importance of the costs 

imposed on human health by radiation 

exposure with other economic and social 

factors. In this respect radiation is not unique, 

and the same statement could be made in 

respect of a number of other agents to which 

mankind is exposed. 

The bases for deciding what is reasonably 

achievable in dose reduction 

(72) Many of the factors described in the 

preceding paragraphs will not be necessary 

for deciding what is reasonably achievable in 

dose reduction below the recommended 

limits. For this purpose the question is 

whether or not the activity is being performed 

at a sufficiently low level of collective dose 

equivalent (and usually, therefore, of detriment) so that any further reduction in dose 

would not justify the incremental cost required to accomplish it. In making this determination, the cost-benefit analysis shifts 

from a consideration of the total benefit of 

the activity to the change in net benefit that 

might be involved in requiring the activity to 

be performed at one level of dose rather than 

another. 

(73) The net benefit, B, of a product or an 

operation involving irradiation can be 

regarded as equal to the difference between its 

gross benefit, V, and the sum of three components: the basic production cost, P, the cost 

.of achieving a selected level of protection, X, 

and the cost, YL of the dc 

the operation or in the p 

disposal of the product, sc 

B= V—{P + 

Cost as used r ere includ 

purely econom ccosts. 

(74) In order to determi 

tion in exposure is "reasoi 

is necessary to consider o 

increase of benefit from st 

on the other the increase o; 

achievement. In the diffei 

analysis, intended to maxii 

the independent variable h 

equivalent, S, 

mum net benefit would be 

dV_ 

dS 

Since Kand/> 

from the r 

dJP 

~dS 

dX 

d? 

can be consi* 

S for a given practice, i 

optimization condition is 

S*such thatt 

tion per unit 

reduction o 

equivalent, i.e 

'.. ie increase ir 

dose equiv 

detriment 

(l i 

However, other compon 

detriment, such as restrict! 

or use of areas, will not nor 

the collective dose equiva 

some cases, be influenced 1 

equivalent in the exposed gi 

(75) Assessments base 

equation may be helped b> 

a monetary value to the uni 

equivalent. Although in \ 

difficult to quantify even 

ponents of tlie detriment, s 

the cost equivalent of a ma 

published, and, with all the 

provide possible quantita; 

decision-ma ring process (s 

tion 22). 
:RP 

MITATION 

tbe the same, this broad process 

; would, however, be legitimate 

etriment to each individual does 

n acceptable level. In exercising 

in relation to ionizing radiation, 

al limitation of detriment would 

by compliance with the Commis-

;quivalent limits. 

ay thus be necessary to make 

ilue judgments in order to comlative importance of the costs 

i human health by radiation 

ith other economic and social 

lis respect radiation is not unique, 

ne statement could be made in 

number of other agents to which 

exposed. 

>r deciding what is reasonably 

t dose reduction 

i of the factors described in the 

iragraphs will not be necessary 

what is reasonably achievable in 

[ion below the recommended 

this purpose the question is 

ot the activity is being performed 

ntly low level of collective dose 

ind usually, therefore, of detritt any further reduction in dose 

justify the incremental cost re-

:omplish it. In making this deterhe cost-benefit analysis shifts 

ideration of the total benefit of 

to the change in net benefit that 

olved in requiring the activity to 

d at one level of dose rather than 

iet benefit, B, of a product or an 

involving irradiation can be 

.qual'to the difference between its 

t, V, and the sum of three combasic production cost, P, the cost 

a selected level of protection, X, 

RECOMMENDATIONS OF THE ICRP 

and the cost, Y, of the detriment involved in 

th.e operation or in the production, use and 

disposal of the product, so that 

B= V—(P-rX+ Y) 

Cost as used here includes social as well as 

ourely economic costs. 

(74) In order to determine whether a reduction in exposure is "reasonably achievable" it 

is necessary to consider on the one hand the 

increase of benefit from such a reduction and 

on the other the increase of cost involved in its 

achievement. In the differential cost-benefit 

a nalysis, intended to maximize the net benefit, 

th.e independent variable is the collective dose 

equivalent, S, from the practice. The optimum net benefit would be attained if 

dy_fdP dX dY\_ 

dS \dS + dS + dSJ~ 

Since KandPcan be considered constant with 

V for a given practice, it follows that the 

optimization condition is fulfilled at a value 

S* such that the increase in the cost of protection per unit dose equivalent balances the 

reduction of detriment per unit dose 

equivalent, i.e. 

d_T\ 

dSjs. \dSjSa 

However, other components of radiation 

detriment, such as restrictions in the access to 

or use of areas, will not normally be related to 

the collective dose equivalent and may, in 

some cases, be influenced by the highest dose 

equivalent in the exposed group. 

(75) Assessments based on the above 

equation may be helped by the assignment of 

a monetary value to the unit of collective dose 

equivalent. Although in practice it is very 

difficult to quantify even some of the components of the detriment, several estimates of 

the cost equivalent of a man sievert have been 

published, and, with all their limitations, they 

provide possible quantitative inputs to the 

decision-making process (see ICRP Publication 22). 

15 

(76) The application of the processes 

described in preceding paragraphs does not 

always provide sufficient protection for the 

individual, particularly when benefits and 

costs are not identically distributed through 

the population. For a given practice, regardless of the result of the differential costbenefit analysis, individual dose-equiv£.lent 

limits must be respected. If the use of the 

optimal collective dose equivalent would 

cause any individual to exceed an approp riate 

limit, it would be necessary to set the collective 

dose equivalent at the point where individual 

dose-equivalent limits would be respected. 

Dose-equivalent limits—general 

(77) The dose equivalent limits forrherly 

recommended by the Commission have been 

in effect for over 20 years. They have been 

widely used internationally and have been 

incorporated into legislation in a numt er of 

countries and regions. Furthermore, there is 

no evidence to indicate that the Commisi ion' s 

recommended system of dose limitation has 

failed to provide an adequate level of safety. 

However, the Commission believes tha t it is 

appropriate to review its dose-equivalent 

limits in the light of present knowledjje, to 

determine whether any change in the levels is 

called for. The Commission's recommended 

dose-equivalent limits are discussed in paragraphs 103-108. 

(78) Almost every exposure of the body 

involves the irradiation of more than one 

tissue, and therefore, for reasons referred to 

in paragraph 36, the Commission believes 

that, for stochastic effects, it is appropriate to 

recommend a dose-equivalent limit based on 

the total risk of all tissues irradiated. This 

system incorporates the setting of a single 

dose-equivalent limit for uniform irradiation 

of the whole body (see paragraphs 104 and 

119) and a system designed to ensure tnat the 

total risk from irradiation of parts of the body 

does not exceed that from uniform irradiation 

of the whole body (see paragraphs 104, 105 

and 125). The system is further subject to the 
P.23 

16 RECOMMENDATIONS OF THE ICRP 

constraint that no single tissue should receive 

more than a specified dose-equivalent limit to 

prevent the occurrence of non-stochastic 

damage (see paragraphs 103 and 126). Ideally, 

the recommendations of the Commission 

should be designed to ensure that the 

detriment from any year's practice should be 

limited to a value independent of the distribution of dose equivalent within the body. 

(79) The Commission's dose limitations are 

intended to relate to the dose-equivalent commitment resulting from 1 year of a particular 

practice. With most external irradiation, and 

with short-lived radionuclides taken into the 

body, the committed dose equivalent from a 

year of practice will be received either instantaneously or within a short time, and thus 

should be subject to the limit for that year. 

However, the committed dose equivalent 

from 1 year's intake of a long-lived radionuclide refers to dose equivalents delivered 

over a long period, even up to many years, 

after the year in question. In principle, the use 

of the dose-equivalent commitment concept 

does permit the dose equivalent received in a 

single year to exceed the annual limit (e.g. in 

the case of an intake in 1 year of a material of 

long effective half life, followed by an intake 

in the next year equal to an ALI* of a material 

of short effective half life). In practice such 

situations will be rare and the dose equivalent 

during any year in excess of the annual limit 

will normally be small. 

(80) The Commission considers that, in 

assessing risks for the purposes of setting the 

dose-equivalent limit for individuals, the 

hereditary detriment in the immediate 

offspring of an individual (i.e. in the first two 

generations after irradiation) should be added 

to the total of any radiation-induced somatic 

detriment. The present indications are that a 

substantial part of the total hereditary harm 

appears in these first two generations of an 

individual's offspring. The harm to be 

received by all subsequent generations would 

•Annual Limit of Intake. 

need to be considered in any assessment of 

total hereditary effects. The reproductive life 

of workers exposed to radiation is considered 

to last about one third of their working career, 

and the Commission has therefore taken this 

factor into account in deriving the weighting 

factors given in paragraph 105. 

(81) The Commission's recommendations 

deal quite differently with two distinct conditions of exposure: 

(i) in which the occurrence of the exposure 

is foreseen and can be limited by 

control of the source and by the application of the Commission's system of 

dose limitation, including the development of satisfactory operating procedures; 

(ii) in which the source of exposure is not 

subject to control, so that any subsequent exposure can be limited in 

amount, if at all, only by remedial 

actions. 

When a source of exposure is subject to 

control it is feasible to apply the Commission's system of dose limitation (see paragraph 

12). Once such a system has been established, 

the objective should be to plan the use of 

radiation sources in such a way that, in 

normal practice, the system will not be 

infringed. The dose-equivalent limits assume 

the additional critical function of acting as a 

check on proper and adequate working 

practices at the source of exposure. The doseequivalent limits should not be regarded as a 

dividing line between safety and danger; when 

limits have been exceeded by a small amount it 

is generally more significant that there has 

been a failure of control than that one or more 

individuals have slightly exceeded a certain 

agreed dose. 

(82) In many practical situations it will be 

convenient to make use of a derived limit, 

calculated with the aid of a model, which provides a quantitative link between a particular 

measurement and the re 

equivalent limit or inta 

paragraph 140 et seq.). Ini 

the intention should be tc 

such that adherence to it * 

certainty of compliance 

sion's recommended dose 

However, failure to adh< 

limit will not necessarily 

achieve compliance with 

recommendations and m 

more careful study of the c 

matter is discussed in grea 

F. 

(83) The Commission's 

are intended to limit s 

individuals, hereditary eff 

ate offspring of irradiate 

hereditary and somatic ef I 

tion as a whole. It is thet 

consider the exposure of bi 

populations. The Commis: 

ed dose limits apply to tw 

posure, nameiy occupatic 

general exposure (see para 

organ or tissue the limit 

equivalent shall refer to the 

dose equivalents contrib 

sources and committed dos 

radioactivity taken hi:o th 

year of practice. In relation 

limits, the dose equivalent 

include contributions fror. 

cedure or from "normal'' 

(see also paragraphs 87-93 

(84) The dose-equivalei 

been established for occu 

are regarded as upper Iir. 

equivalents may have t 

monitored and controlled 

limits are not exceeded. 1 

equivalent for members of 

theoretical concept, inten 

the design and operation o 

makes it unlikely that indiv 

will receive more than t 

equivalent. The effectiv 

checked by assessments 
ICRP 

considered in any assessment of 

itary effects. The reproductive life 

exposed to radiation is considered 

:t one third of their working career, 

mmission has therefore taken this 

account in deriving the weighting 

:n in paragraph 105. 

• Commission's recommendations 

iifferently with two distinct condilosure: 

hich the occurrence of the exposure 

oreseen and can be limited by 

rol of the source and by the appli3n of the Commission's system of 

.- limitation, including the developt of satisfactory operating proves; 

hich the source of exposure is not 

eet to control, so that any subseit exposure can be limited in 

•unt, if at all, only by remedial 

3ns. 

ource of exposure is subject to 

is feasible to apply the Commism of dose limitation (see paragraph 

uch a system has been established, 

ive should be to plan the use of 

sources in such a way that, in 

actice, the system will not be 

The dose-equivalent limits assume 

nal critical function of acting as a 

proper and adequate working 

'. the source of exposure. The doselimits should not be regarded as a 

e between safety and danger; when 

been exceeded by a small amount it 

y more significant that there has 

ire of control than that one or more 

• have slightly exceeded a certain 

lany practical situations it will be 

to make use of a derived limit, 

vith the aid of a model, which prontitative link between a particular 

RECOMMENDATIONS OF THE ICRP 17 

measurement and the recommended dosecjuivalent limit or intake limit (see also 

paragraph 140 et seq.). In deriving such a limit 

: he intention should be to establish a figure 

>:.tch that adherence to it will provide virtual 

certainty of compliance with the Commission's recommended dose-equivalent limits. 

However, failure to adhere to the derived 

limit will not necessarily imply a failure to 

achieve compliance with the Commission's 

recommendations and may require only a 

more careful study of the circumstances. This 

matter is discussed in greater detail in section 

F. 

(83) The Commission's recommendations 

;re intended to limit somatic effects in 

individuals, hereditary effects in the immediate offspring of irradiated individuals, and 

hereditary and somatic effects in the population as a whole. It is therefore necessary to 

.msider the exposure of both individuals and 

populations. The Commission's recommended dose limits apply to two categories of exposure, namely occupational exposure and 

general exposure (see paragraph 137). In any 

organ or tissue the limitation of the dose 

equivalent shall refer to the sum of the annual 

dose equivalents contributed by external 

>ources and committed dose equivalents from 

radioactivity taken into the body during any 

year of practice. In relation to dose-equivalent 

limits, the dose equivalent shall not be held to 

include contributions from any medical procedure or from "normal" natural radiation 

(see also paragraphs 87-93). 

(84) The dose-equivalent limits that have 

been established for occupational exposure 

are regarded as upper limits, and the dose 

equivalents may have to be individually 

monitored and controlled to ensure that the 

limits are not exceeded. Limitation of dose 

equivalent for members of the public is a more 

theoretical concept, intended to ensure that 

the design and operation of radiation sources 

makes it unlikely that individuals in the public 

will receive more than the specified dose 

equivalent. The effectiveness of this is 

checked by assessments through sampling 

procedures and statistical calculations, and 

by control of the sources from which the 

exposure is expected to arise, and only rarely 

by spot checks of individual exposures. 

(85) The basis for the limitation of individual exposures, either of workers or of 

members of the public, is the limit for tne 

weighted mean whole body dose equivalent 

(see paragraph 104) and not the derived limits 

or levels by which the dose is controlled. The 

actual doses received by individuals will vary 

depending on factors such as differences in 

their age, size, metabolism and customs, as 

well as variations in their environment. With 

an occupationally-exposed individual it will 

often be sufficient to use derived limits and 

levels to assess his exposure status. With 

exposure of members of the public it is usually 

feasible to take account of these sources of 

variability by the selection of appropriate 

critical groups within the population 

provided the critical group is small enough to 

be relatively homogeneous with respect to 

age, diet and those aspects of behaviour that 

affect the doses received. Such a group should 

be representative of those individuals in the 

population expected to receive the highest 

dose equivalent, and the Commission believes 

that it will be reasonable to apply the 

appropriate dose-equivalent limit for individual members of the public to the weighted 

mean dose equivalent of this group. Because 

of the innate variability within an apparently 

homogeneous group some members of the 

critical group will in fact receive dose equivalents somewhat higher than the mean. However, because of the maximizing assumptions 

used, the dose equivalent actually received 

will usually be lower than the estimated dose 

equivalent (see also section G). 

(86) Before discussing the limitation of 

doses in different conditions of exposure, it is 

first necessary to review the relationship of 

the Commission's recommended doseequivalent limits to exposures from natural 

radiation and of patients from medical 

procedures. 
P.25 

18 RECOMMENDATIONS OF THE ICRP 

Natural radiation and dose-equivalent limits 

(87) Man has always been exposed to radiation from his natural environment, the basic 

sources of natural radiation exposure being 

cosmic rays, radioactivity in rocks and soil, 

and radioactive nuclides incorporated into his 

tissues. The dose of natural radiation that a 

person receives depends on a number of 

factors such as the height above sea-level at 

which he lives, the amount and type of 

radioactive nuclides in the soil in his neighbourhood, and the amount that he takes into 

his body in air, water and food. The total 

absorbed dose rate in most human tissues 

from natural radiation is about onethousandth of a gray per year, but absorbed 

dose rates up to one-hundredth of a gray per 

year, or more, have been reported from 

certain limited areas of the world. 

(88) Man-made modifications of the environment and man's activities can increase 

the "normal" exposure to natural radiation. 

Examples of this include mining, flight at high 

altitudes, and the use of building materials 

containing naturally-occurring radioactive 

nuclides. Even living within a house is often 

sufficient to increase radiation exposure 

because restricted ventilation tends to lead to 

an accumulation of radioactive gases and 

their decay products. 

(89) In radiation protection the Commission's recommended dose-equivalent limits 

have not been regarded as applying to, or 

including, the "normal" levels of natural 

radiation, but only as being concerned with 

those components of natural radiation that 

result from man-made activities or in special 

environments. This convention, valid on the 

assumption of linearity (see paragraphs 27-

30), is justified in the sense that the Commission's recommended limits are intended as 

guides for planning purposes, and thus 

primarily apply to man-made practices. 

Clearly, however, there is no sharp dividing 

line between levels of natural radiation that 

can be regarded as "normal" and those that 

are more elevated owing to human activities 

or choice of environment. There will therefore be instances in which judgment will have 

to be exercised as to whether the component 

of increased natural radiation should or 

should not be subject to the Commission's 

recommended system of dose limitation. 

(90) It should be emphasized moreover 

that, on the premise that the frequency of 

radiation effects is linearly proportional to 

the dose received, such harm as may be caused 

by natural radiation could be regarded as 

independent of, and simply additive to, the 

amount of harm that may be caused by any of 

the man-made practices involving radiation 

exposure to which the Commission's limits 

apply. In this sense, regional variations in 

natural radiation are regarded as involving a 

corresponding variation in detriment in just 

the same way as, for example, regional variations in meteorological conditions or volcanic 

activity involve differences in the risk of harm 

in different areas. On this basis there is no 

reason why differences in natural radiation 

should affect acceptable levels of man-made 

exposure, any more than differences in other 

natural risks should do. 

Medical exposures of patients and 

dose-equivalent limits 

(91) In these recommendations "medical 

exposure" refers to the intentional exposure 

of patients for diagnostic and therapeutic 

purposes, and to the exposures resulting from 

the artificial replacement of body organs or 

functions (e.g. by heart pumps and cardiac 

pace-makers). It applies to exposures 

administered by medical and paramedical 

personnel. It does not refer to the irradiation 

of the staff involved in the administration of 

medical exposures to patients, nor to the 

irradiation of one patient by another. 

(92) Medical exposure is, in general, subject 

to most of the Commission's system of dose 

limitation, that is: unnecessary exposures 

should be avoided; necessary exposures 

should be justifiable in terms of benefits that 

would not otherwise have been received; and 

the doses actually administered should be 

limited to the minimum 

with the medical benef 

patient. The individual re 

is himself the direct reci 

resulting from the procec 

it is not appropriate to ai 

values of the Commiss 

dose-equivalent limits to 

With certain medical exr 

higher level of risk may ii 

the benefit derived than b 

the Commission to be ai 

pational exposure or for e 

ofthe public. 

(93) It has already bee 

graph 89 that the Co 

mended dose-equivalent 

for planning purposes an 

ponent "of risk resulting 

practice to which radiatio 

Under the assumption c 

from such a practice is un 

from other sources, and i 

able to consider separatei 

from such practices frorr 

from medical exposure. 

siderations detailed in 

Commission considers tl 

resulting from medical e> 

influence any of the p 

limitation applied to exr 

sources. However, becau 

of non-stochastic effects 

exceptional cases of workgone radiodiagnosis or r; 

ing heavy irradiation of p: 

whose work would involv 

ure of those parts, the 

should be reviewed by the 

authority. 

Implications for non-stoc 

(94) As already stated, 

recommended dose-equi\ 

limitation of stochastic ef; 

contributions from natur: 

or from medical exposi 
CRP 

ances in which judgment will have 

ised as to whether the component 

;d natural radiation should or 

be subject to the Commission's 

•ed system of dose limitation, 

hould be emphasized moreover 

e premise that the frequency of 

ffects is linearly proportional to 

^ived, such harm as may be caused 

radiation could be regarded as 

t of, and simply additive to, the 

iarm that may be caused by any of 

ade practices involving radiation 

) which the Commission's limits 

his sense, regional variations in 

iation are regarded as involving a 

ing variation in detriment in just 

ty as, for example, regional variaeorological conditions or volcanic 

olve differences in the risk of harm 

: areas. On this basis there is no 

• differences in natural radiation 

ct acceptable levels of man-made 

ny more than differences in other 

s should do. 

oosures of patients and 

ilent limits 

hese recommendations "medical 

refers to the intentional exposure 

: for diagnostic and therapeutic 

nd to the exposures resulting from 

il replacement of body organs or 

z.g. by heart pumps and cardiac 

s). It applies to exposures 

:d by medical and paramedical 

It does not refer to the irradiation 

involved in the administration of 

posures to patients, nor to the 

of one patient by another. 

ical exposure is, in general, subject 

the Commission's system of dose 

that is: unnecessary exposures 

avoided; necessary exposures 

jstifiable in terms of benefits that 

Hherwise have been received; and 

actually administered should be 

RECOMMENDATIONS OF THE ICRP 19 

limited to the minimum amount consistent 

vith the medical benefit to the individual 

patient. The individual receiving the exposure 

h himself the direct recipient of the benefit 

resulting from the procedure. For this reason 

it is not appropriate to apply the quantitative 

values of the Commission's recommended 

dose-equivalent limits to medical exposures. 

With certain medical exposures a very much 

higher level of risk may in fact be justified by 

the benefit derived than by the level judged by 

the Commission to be appropriate for occupational exposure or for exposure of members 

ofthe public. 

(93) It has already been indicated in paragraph 89 that the Commission's recommended dose-equivalent limits are intended 

: or planning purposes and refer to that component 'of risk resulting from a particular 

practice to which radiation protection applies. 

Under the assumption of linearity the risk 

i rom such a practice is unaffected by the risks 

"rom other sources, and it is therefore justifiable to consider separately the doses received 

irom such practices from the doses acquired 

from medical exposure. In view of the considerations detailed in paragraph 92, the 

Commission considers that radiation doses 

resulting from medical exposures should not 

influence any of the procedures of dose 

limitation applied to exposures from other 

sources. However, because of the possibility 

of non-stochastic effects developing in the 

exceptional cases of workers who have undergone radiodiagnosis or radiotherapy involving heavy irradiation of part of the body, and 

whose work would involve substantial exposure of those parts, the working situation 

should be reviewed by the competent medical 

authority. 

Implications for non-stochastic effects 

(94) As already stated, the Commission's 

recommended dose-equivalent limits for the 

limitation of stochastic effects do not apply to 

contributions from natural radiation sources 

or from medical exposure. However, the 

question of non-stochastic effects merits consideration. 

(95) When exposure is limited by consideration of stochastic effects, it is unlikely that the 

addition of occupational exposures and 

normal medical or natural radiation exposures would cause a total dose equivalent that 

would be near threshold values of any harmful non-stochastic effect. Although, in 

principle, contributions to the dose 

equivalent from all sources (i.e. also from 

medical sources and normal natural background) should be added in assessing the likelihood of non-stochastic damage occurring, 

the Commission considers that in practice it is 

not necessary that this should be done. High 

doses from natural radiation sources would 

only be expected to occur.under the special 

conditions mentioned in paragraph 89 and 

should in any case then be included under the 

dose-equivalent limits to the extent that the 

elevated exposures are subject to human 

control. In the case of high medical exposures 

(e.g. in radiotherapy) it would be the doses 

from these exposures that would dominate, 

and the consideration of possible risks of nonstochastic effects (e.g. to the lens of the eye) 

would be part of the medical considerations in 

the treatment of the patient, rather than the 

task of those responsible for radiation 

protection in general. 

Dose-equivalent limits for workers 

(96) As stated in paragraph 77, the Commission's recommended dose-equivalent 

limits for occupational exposure have been in 

effect for over 20 years. In view of the 

emphasis that the Commission places on risk 

estimations, it believes it appropriate to assess 

the levels of risk that are associated with its 

dose-equivalent limits. The Commission 

believes that for the foreseeable future a valid 

method for judging the acceptability of the 

level of risk in radiation work is by comparing 

this risk with that for other occupations 

recognized as having high standards of safety, 

which are generally considered to be those in 
P.27 

20 RECOMMENDATIONS OF THE ICRP 

which the average annual mortality due to 

occupational hazards does not exceed 10-4*. 

In most occupations, fatalities, whether due 

to accidents or disease, are accompanied by a 

much larger number of less severe consequences. Radiation exposure, on the other 

hand, at levels imposed by adherence to 

recommended dose-equivalent limits, is expected to cause very few injuries or illnesses in 

exposed workers other than any malignant 

diseases which may be induced. In assessing 

the implication of dose-equivalent limits 

therefore the Commission believes that the 

calculated rate at which fatal malignancies 

•might be induced by occupational exposure to 

radiation should in any case not exceed the 

occupational fatality rate of industries recog-

' nized as having high standards of safety. 

(97) Other criteria than fatality rates could 

be used in ensuring that radiation exposure, as 

controlled by recommended dose-equivalent 

limits, involves no greater hazard than in 

other safe industries. Ideally, account should 

be taken of all components of the harm, or 

detriment, involved in the various occupations 

—including the sum of all accidents, illnesses, 

genetic defects and fatalities involved, as well 

as the aaxieties of workers or their families 

about the hazards or conditions of work in 

different industries. As a first approximation 

it can be stated that an assessment based only 

on the mortality criterion can be regarded as 

•conservative since experience has shown that 

the non-fatal effects of irradiation are much 

less frequent than the non-fatal effects 

encountered in other safe occupations. 

However, the summation and comparison of 

the diverse contributions to total detriment 

are difficult to make on an objective basis. 

(98) Account can be taken of some 

components of disability by estimating the 

average amount of time lost (e.g. per worker 

year) from full activity—whether from accidents, industrial disease or, in the extreme 

case, by death from occupational causes. A 

review of the problems involved in developing 

any "Index of Harm" on this basis is given in 

a report on this topic being prepared for the 

Commission; however, no such criterion can 

be regarded as more than indicative of broad 

differences in risk. It should be mentioned, 

however, that an accidental death appears to 

involve an average loss of about 30 years of 

life in many industries, and to be associated 

with an approximately equal total loss of 

working time from industrial accidents. A 

fatal malignancy induced by occupational 

exposure to radiation would be expected to 

involve the loss of about 10 years of life, 

owing to the long latency in the development 

of such a condition, without appreciable 

associated time loss from accidents. 

(99) When making comparisons with other 

safe occupations, it should be realised that the 

level of risk representative of a safe occupation relates to the average risk for all workers 

.in that occupation, the risk for individual 

workers varying with their job and being 

distributed around this average. A similar 

distribution of individual risks also occurs in 

radiation work; in many cases of occupational 

.exposure where the Commission's system of 

dosehmitation has been applied, the resultant 

annual average dose equivalent is no greater 

than one-tenth of the annual limit .t Therefore 

the application of a dose-equivalent limit provides much better protection for the average 

worker in the group than that corresponding 

to the limit. 

(100) In the case of uniform exposure of the 

whole body, in circumstances where the Commission's recommendations, including the 

annual dose-equivalent limit of 50 mSv, have 

been applied, the distribution of the annual 

dose equivalents in large occupational groups 

has been shown very commonly to fit a lognormal function, with an arithmetic mean of 

about 5 mSv, and with very few values 

approaching the limit. The application of the 

risk factors given in paragraphs 40-60 to the 

above mean dose indicates that the average 

risk in these radiation occupations is com-

•See the Commission's report on Problems Involved in Developing an Index ofHarm (in preparation). 

TSee Annex.E of the 1977 Report of the United Nations Scientific Committee on the Effects of Atomic Radiation. 

parable with the average 

industries (but see also par 

(101) The Commissioi 

limits are primarily in 

adequate protection even 

exposed individuals, in 

workers who are expose 

equivalent limits are unlil 

doses each year of their oc 

it would be their expei 

equivalent that would i; 

individual risk. In thi: 

comparable with individu; 

randomly to higher risks 

tions. Exposures consiste; 

would be comparable with 

higher-than-average risk i 

for certain individuals in n 

tries. 

(102) However, if the e: 

in any particular occup 

planned so that a large f 

received dbse equivalents 

the annual limit, the aver; 

rise substantially above on 

There would thus be a co 

the average risk, even thou 

equivalent limit was not 

individual worker. Long-c 

of a considerable proportit 

or near the dose-equivalen 

be acceptable if a careful cc 

had shown that the hig 

would be justified. 

Recommended dose-equ 

The Commission's recc 

intended to prevent non 

and to limit the occurr 

effects to an acceptable U 

sion believes that non-sto 

be prevented by applying 

limitof0.5Sv(50rem)in 

except the lens, for whic 

recommends a limit of 0. 

year. These limits appi 

whether the tissues are 

together with other org; 
P.28 

RECOMMENDATIONS OF THE ICRP 

of Harm" on this basis is given in 

this topic being prepared for the 

i; however, no such criterion can 

as more than indicative of broad 

in risk. It should be mentioned, 

at an accidental death appears to 

verage loss of about 30 years of 

industries, and to be associated 

proximately equal total loss of 

.e from industrial accidents. A 

lancy induced by occupational 

radiation would be expected to 

loss of about 10 years of life, 

.• long latency in the development 

condition, without appreciable 

me loss from accidents, 

i making comparisons with other, 

ions, it should be realised that the 

representative of a safe occupa*-

o the average risk for all workers 

ipation, the risk for individual 

ying with their job and being 

around this average. A similar 

of individual risks also occurs in 

Tk; in many cases of occupational 

•ere the Commission's system of 

on has been applied, the resultant 

tge dose equivalent is no greater 

th of the annual limit.t Therefore 

on of a dose-equivalent limit probetter protection for the average 

e group than that corresponding 

e case of uniform exposure of the 

in circumstances where the Comcommendations, including the 

equivalent limit of 50 mSv, have 

i, the distribution of the annual 

ents in large occupational groups 

>wn very commonly to fit a logtion, with an arithmetic mean of 

iv, and with very few values 

the limit. The application of the 

;iven in paragraphs 40-60 to the 

dose indicates that the average 

radiation occupations is com-

\ of Harm'(in preparation). 

:c on the iilTccts of Atomic Radiation. 

p:;rable with the average risk in other safe 

industries (but see also paragraph 29). 

<;01) The Commission's dose-equivalent 

limits are primarily intended to ensure 

adequate protection even for the most highly 

exposed individuals. In many occupations 

•.•••ackers who are exposed near the doseeuuivalent limits are unlikely to receive such 

doses each year of their occupational life and 

it would be their expected lifetime dose 

equivalent that would indicate their total 

individual risk. In this sense they are 

comparable with individuals who are exposed 

randomly to higher risks in "safe" occupations. Exposures consistently near the limits 

would be comparable with a situation where a 

uigher-than-average risk has been identified 

. .far certain individuals in non-radiation indus-

.. tries. 

1102) However, if the exposure of workers 

in any particular occupation were to be 

I'lanned so that a large fraction of workers 

received dose equivalents which approached 

ihe annual limit, the average exposure could 

i :se substantially above one-tenth of the limit. 

There would thus be a corresponding rise in 

i he average risk, even though the annual doseequivalent limit was not exceeded by any 

individual worker. Long-continued exposure 

o f a considerable proportion of the workers at 

or near the dose-equivalent limits would only 

be acceptable if a careful cost-benefit analysis 

had shown that the higher resultant risk 

would be justified. 

Recommended dose-equivalent limits. (103) 

The Commission's recommendations are 

intended to prevent non-stochastic effects 

and to limit the occurrence of stochastic 

effects to an acceptable level. The Commission believes that non-stochastic effects will 

be prevented by applying a dose-equivalent 

limit of 0.5 Sv (50 rem) in a year to all tissues 

except the lens, for which the Commission 

recommends a limit of 0.3 Sv (3Cf rem) in a 

year. These limits apply irrespective of 

whether the tissues are exposed singly or 

together with other organs, and they are 

intended to constrain any exposure that fulfils 

the limitation of stochastic effects (see 

paragraphs 104-110). 

(104) For stochastic effects the Commission's recommended dose limitation is based 

on the principle that the risk should be equal 

whether the whole body is irradiated uniformly or whether there is non-uniform irradiation. 

This condition will be met if 

ZTwTHTZH wb,i» 

where, wT is a weighting factor representing 

the proportion of the stochastic risk resulting 

from tissue (T) to the total risk, when the 

whole body is irradiated uniformly, HT is the 

annual dose equivalent in tissue (7V), //«,b.i is 

the recommended annual dose-equivalent 

limit for uniform irradiation of the whole 

body, namely 50 mSv (5 rem). 

(105) The values of wT recommended by the 

Commission are shown below: 

Tissue 

Gonads 

Breast 

Red bone marrow 

Lung 

Thyroid 

Bone surfaces 

Remainder 

wT 

0.25 

0.15 

0.12 

0.12 

0.03 

0.03 

0.30 

The value of wT for the remaining tissues 

requires further clarification. For the reasons 

stated in paragraphs 58 and 59 the Commission 

recommends that a value of wT = 0.06 is 

applicable to each of the five organs or tissues 

of the remainder receiving the highest dose 

equivalents, and that the exposure of all other 

remaining tissues can be neglected. (When the 

gastro-intestinal tract is irradiated, the 

stomach, small intestine, upper large intestine 

and lower large intestine are treated as four 

separateorgans.) 

(106) It is recognized that the risk associated 

with a given exposure will vary with the age and 

sex of the individual exposed. However, the 

values of wrgiven in paragraph 105 are recommended as appropriate for the protection of 
P.29 

22 RECOMMENDATIONS OF THE ICRP 

any worker, regardless of these sources of 

variability(seealsoparagraph38). 

(107) The values of MY presented in paragraph 105 are intended as guidance for those 

concerned with calculating secondary and 

derived limits (see section F). In particular, 

they are used by ICRP Committee 2 in calculating values of annual limits of intake (ALI) 

for radionuclides, which take account of the 

dose equivalent in each tissue. In practical 

situations, however, it will usually suffice to 

use the two secondary limits that are applicable to external and internal exposure, 

namely, the limit to the dose-equivalent index 

H, (see paragraph 108) and ALI (see paragraph 109). 

(108) With external exposures to penetrating radiation, on those occasions when information is lacking concerning the actual 

distribution of dose equivalent in the body, i* 

is possible to assess the maximum value of 

dose equivalent that would occur in a 30 cm 

sphere (the deep dose-equivalent index, H,)*. 

The limitation of the dose-equivalent index to 

an annual value of 50 mSv would afford a 

level of protection that would be at least as 

good as that provided by the method recommended in paragraph 104. 

(109) With internal exposure resulting from 

the intake of radionuclides protection can be 

based on annual limits of intake (ALI). These 

are calculated by ICRP Committee 2. from 

knowledge of the various organ committed 

dose equivalents per unit intake, by application of the principles discussed in paragraphs 

104 and 105; such exposures are also subject 

to the limits for non-stochastic effects given 

in paragraph 103. 

(110) When external and internal exposures 

are received together, the Commission's 

recommended dose limitation for stochastic 

effects will not be exceeded if: 

"wb.L 'i.i. 

where, //, is the annual dose-equivalent index, 

/7w bL is the annual dose-equivalent limit, 

lj is the annual intake of radionuclide j , IJL is 

the annual limit of intake for radionuclide j . 

(111) Although the Commission no longer 

proposes separate annual dose-equivalent 

limits for individual tissues and organs irradiated singly, the implied values of such limits 

may be obtained, if required, by dividing the 

dose-equivalent limit H^.L (50 mSv in a year) 

by the relevant value of WT. Such values would 

be subject to the limits, based on nonstochastic effects, given in paragraph 103. 

(112) It should be recognized that the limits 

have been derived for application in average 

situations, for all adult ages and for both sexes 

and without regard to individual circumstances which might enhance the risk. The 

Commission believes that, for example, any 

variation in risk with age will not influence the 

total risk from a lifetime exposure unless the 

exposure is limited to a special group. Additional precautions and dose limitations may be 

necessary, however, to limit the irradiation of 

an embryo or foetus in the case of occupational 

exposure of pregnant women (see paragraphs 

115andll6). 

Planned special exposures. (113) Situations 

may occur infrequently during normal 

operations when it may be necessary to permit 

a few workers to receive dose equivalents in 

excess of the recommended limits. In such 

circumstances external exposures or intakes 

of radioactive material may be permitted 

provided the dose-equivalent commitment 

does not exceed twice the relevant annual limit 

in any single event, and, in a lifetime, five 

times this limit. The Commission wishes tc 

•International Commission on Radiaiion Units and Measurements, The Conceptual Basis for the Deicrminalion 

of Dose Equivalent, tCRU Report 25, International Commission on Radiaiion Unils and Measurements, 

Washington, 1976. 

emphasize that external e 

of this magnitude are c 

alternative techniques, wl 

such exposure of wo 

unavailable or imprac 

paragraph 171). 

(114) Planned special e> 

be permitted if the wor 

received abnormal exposu 

equivalents in excess of fi\ 

annual limit. Planned 

should not be permitted f< 

ductive capacity. Dose ec 

from planned special ex 

recorded with those fron 

but any excess over the lim 

paragraphs 103 et seq. si 

constitute a reason for e 

from his usual occupatio. 

emergency exposures are c 

G). 

Occupational exposure x 

ductive capacity. (115) 

reproductive capacity a 

exposed under the limits 

paragraph 108, and whe: 

received at an approximate 

unlikely that any embryo c 

than 5 mSv during the 

pregnancy. Having t 

circumstances in which sui 

occur, the Commission 

procedure will provide aj 

tion during the essential 

genesis. 

Occupational exposure q 

(116) It is likely that any i 

than 2 months' duration 

recognized by the womai 

physician. For reasons dese 

65, the Commission recorr 

pregnancy has been diagnc 

should be made to ensure tl 

continue to work only in V\ 

B, specified in paragraph 11 
ICRP 

" wb. L 'j, L 

s the annual dose-equivalent index, 

he annual dose-equivalent limit, 

-.ual intake of radionuclide j , Ijt L is 

limit of intake for radionuclide j . 

rhough the Commission no longer 

separate annual dose-equivalent 

tdividual tissues and organs irradi-

, the implied values of such limits 

ained, if required, by dividing the 

alent limit //wb,/. (50 mSv in a year) 

ant value of WT. Such values would 

to the limits, based on noneffects, given in paragraph 103. 

hould be recognized that the limits 

derived for application in average, 

for all adult ages and for both sexes -

ut regard to individual circumich might enhance the risk. The 

>n believes that, for example, any 

i risk with age will not influence the 

om a lifetime exposure unless the 

limited to a special group. Additutions and dose limitations may be 

however, to limit the irradiation of 

)r foetus in the case of occupational 

'pregnant women (see paragraphs 

special exposures. (113) Situations 

r infrequently during normal 

when it may be necessary to permit 

:ers to receive dose equivalents in 

he recommended limits. In such 

ces external exposures or intakes 

tive material may be permitted 

he dose-equivalent commitment 

:eed twice the relevant annual limit 

,le event, and, in a lifetime, five 

iimit. The Commission wishes to 

: Conceptual Basis lor the Determination 

n Radiation Units and Measurements, 

RECOMMENDATIONS OF THE ICRP 23 

emphasize that external exposures or intakes 

ol this magnitude are only justified when 

aiternative techniques, which do not involve 

such exposure of workers, are either 

unavailable or impracticable (see also 

paragraph 171). 

(114) Planned special exposures should not 

bo permitted if the worker has previously 

received abnormal exposures resulting in dose 

•-ouivalents in excess of five times the relevant 

annual limit. Planned special exposures 

.hould not be permitted for women of reproductive capacity. Dose equivalents resulting 

irom planned special exposures should be 

secorded with those from usual exposures, 

but any excess over the limits recommended in 

paragraphs 103 et seq. should not by itself 

constitute a reason for excluding a worker 

from his usual occupation. (Accidental and 

emergency exposures are discussed in section 

G). 

Occupational exposure of women of reproductive capacity. (115) When women of 

reproductive capacity are occupationally 

exposed under the limits recommended in 

paragraph 108, and when this exposure is 

received at an approximately regular rate, it is 

unlikely that any embryo could receive more 

than 5 mSv during the first 2 months of 

pregnancy. Having regard to the 

circumstances in which such exposures could 

occur, the Commission believes that this 

procedure will provide appropriate protection during the essential period of organogenesis. 

Occupational exposure of pregnant women. 

(116) It is likely that any pregnancy of more 

than 2 months' duration would have been 

recognized by the woman herself or by a 

physician. For reasons described in paragraph 

65, the Commission recommends that, when 

pregnancy has been diagnosed, arrangements 

should be made to ensure that the woman can 

continue to work only in Working Condition 

B, specified in paragraph 161. 

Dose-equivalent limits for individual members of the public. (117) Radiation risks are a 

very minor fraction of the total number of 

environmental hazards to which members of 

the public are exposed. It seems reasonable 

therefore to consider the magnitude of radiation risks to the general public in the light of 

the public acceptance of other risks of everyday life. This acceptance (when related to 

risks that could not be reduced or avoided 

entirely) is motivated by the benefits that 

would not otherwise be received, by an assessment of the social cost of achieving a possible 

reduction of risk, or by an implicit judgment 

that the risk is negligible. 

(118) The acceptable level of risk for 

stochastic phenomena for members of the 

general public may be inferred from consideration of risks that an individual can modify to 

only a small degree and which, like radiation 

safety, may be regulated by national ordinance. An example of such risks is that of using 

public transport. From a review of available 

information related to risks regularly accepted ' 

in everyday life, it can be concluded that the 

level of acceptability for fatal risks to the 

general public is an order of magnitude lower 

than for occupational risks. On this basis, a 

risk in the range of IO-6 to IO"5 per year would 

be likely to be acceptable to any individual 

member of the public. 

(119) The assumption of a total risk of the 

order of 10"2 Sv1 (see paragraph 60) would 

imply the restriction of the lifetime dose to the 

individual member of the public to a value 

that would correspond to 1 mSv per year of 

life-long whole body exposure. For the 

reasons given in the following paragraphs, the 

Commission's recommended whole body 

dose-equivalent limit of 5 mSv (0.5 rem) in a 

year, as applied to critical groups, has been 

found to provide this degree of safety and the 

Commission recommends its continued use 

under the conditions specified in paragraphs 

120-128. 

(120) The application of an annual doseequivalent limit of 5 mSv to individual 

members of the public is likely to result in 
P.31 

24 RECOMMENDATIONS OF THE ICRP 

average dose equivalents of less than 0.5 mSv, 

provided that the practices exposing the 

public are few and cause little exposure 

outside the critical groups (see paragraph 85). 

When applying the dose-equivalent limit for 

members of the public, consideration must be 

given to the possibility that some individuals 

may belong to more than one critical group, 

ln fact, due to the maximizing assumptions 

usually made in selecting critical groups, the 

doses actually received by the most highly 

exposed individuals will in most cases be 

considerably lower than the doses postulated 

for the critical group. 

(121) The actual value of the average dose 

depends upon both the result of the optimization process of a large number of justified 

practices causing radiation exposures and the 

value selected to limit the individual doses. If 

at some time in the future the combined 

exposure resulting from optimized exposures 

resulted in average dose equivalents higher 

than 1 mSv in a year, the situation might still 

be justifiable, even though the average risk 

for members of the public would be higher 

than the range 10-* to 10~5 per year. 

(122) In some cases optimization, which 

could be the overriding protection criterion, 

will necessitate a more realistic selection of the 

critical group, because to overestimate the 

risk would introduce a bias which would 

invalidate the optimization. In these cases, the 

dose-equivalent limit to individual members 

of the public, referred to in paragraph 120, 

would still adequately restrict the average 

dose equivalent, but the few individuals 

exposed to the dose-equivalent limit could run 

a risk in the range of 10-5 to 10-4 per year. This 

annual risk would then be one order of 

magnitude higher than the risk range quoted 

in paragraph 118. Since exposures at the doseequivalent limit are not likely to be repeated 

over many years, however, an adequate 

restriction of the life-time dose is still likely to 

be achieved. In any rare cases where the doses 

to a few individuals were actually found to be 

received at high rates over prolonged periods, 

it would be prudent to take measures to restrict 

their life-time dose as implied in paragraph 

119. 

(123) In such cases, where optimization is 

the deciding protection criterion and where 

critical groups are selected on the basis of 

realistic assumptions, it would be appropriate 

to use as a boundary condition of any single 

optimization process an individual dose limitation such as indicated in paragraph 122. 

Even the few individuals who would actually 

receive doses of this magnitude over a long 

period of time would not be subject to risks 

appreciably above the level that is generally 

considered acceptable (see paragraph 118). 

(124) In most applications, however, 

administrative planning is based on operational limits derived from very crude costeffectiveness considerations of protective 

measures and quite conservative estimates of 

the resulting doses in critical groups. For such 

planning it is usually quite appropriate to 

assess the doses in the critical group in relation 

to the dose-equivalent limit of 5 mSv in a year, 

and the Commission has found no reason to 

recommend a change in this practice. The 

main reason for this decision is that the Commission's system of dose limitation, with the 

dose-equivalent limit of 5 mSv in a year, is 

found to provide the necessary degree cf 

safety, under the boundary conditions stated 

in paragraphs 120-123, and that a change in 

the upper limit would not be of the same 

importance from the radiation protection 

point of view as the rigorous application of 

the principle of keeping all doses as low as is 

reasonably achievable. 

(125) For non-homogeneous exposure." 

with organ doses HT, the limitation condition 

is Y.T

W

THT ^ H'^ L, where/^,;, L isthedoseequivalent limit for uniform irradiation of the 

whole body for a member of the public. Due 

to different age distributions when members 

of the public are irradiated, the risks will not 

be quite the same as for occupational 

exposures. The relative risks, however, will 

differ but little and the Commission has not 

found the differences significant enough to 

recommend a separate set of weighting 

factors, different from th 

in paragraph 105 (see also 

(126) In order to preve 

(issue from receiving a to 

contribute significantly : 

non-stochastic effects, a: 

dose-equivalent limit of 5' 

This limit is consideral 

corresponding limits rea 

vention of non-stochastic 

pational exposure. The it 

that the longer exposu 

practical difficulties in c 

exposure from all source 

threshold doses for not 

being reached. The wc 

recommended in paragrar 

provide the necessary limi 

stochastic effects, but the 

needed for the skin and the 

(127) In the calculation 

lent incurred by members 

intake of radionuclides, 

taken of differences in org 

characteristics of ehildn 

differences may be found 

task group on Refere 

Publication 23). 

(128) As with workers ( 

an increase in the average t 

the public could result fror 

in the number of sources 

though each satisfactorily 

justification and optimi 

graphs 68-76) and caused; 

the recommended limii 

regional authorities shoe 

under surveillance the sep; 

from all practices to the a 

the whole population so a 

single source or practk 

unjustified amount to the; 

that no individual receives 

a result of membership of i 

groups. 

Exposure of populations 

(129) In its previous rec 
ICRP 

me dose as implied in paragraph 

such cases, where optimization is 

g protection criterion and where 

ups are selected on the basis of 

umptions, it would be appropriate 

boundary condition of any single 

>.n process an individual dose limitas indicated in paragraph 122. 

•w individuals who would actually 

es of this magnitude over a long 

ime would not be subject to risks 

/ above the level that is generally 

acceptable (see paragraph 118). 

t most applications, however, 

:ive planning is based on opera-

:s derived from very crude costss considerations of protective 

nd quite conservative estimates of 

g doses in critical groups. For such 

. is usually quite appropriate to 

oses in the critical group in relation 

equivalent limit of 5 mSv in a year, 

mmission has found no reason to 

1 a change in this practice. The 

a for this decision is that the Comystem of dose limitation, with the 

tlent limit of 5 mSv in a year, is 

provide the necessary degree of 

er the boundary conditions stated 

';hs 120-123, and that a change in 

limit would not be of the same 

from the radiation protection 

:w as the rigorous application of 

e of keeping all doses as low as is 

achievable. 

>r non-homogeneous exposures 

doses HT, the limitation condition 

^ H'wb.Lt whereH^.L isthedoseimit for uniform irradiation of the 

for a member of the public. Due 

age distributions when members 

:c are irradiated, the risks will not 

the same as for occupational 

The relative risks, however, will 

ittle and the Commission has not 

differences significant enough to 

1 a separate set of weighting 

RECOMMENDATIONS OF THE ICRP 25 

factors, different from the values of wTgiven 

ir: paragraph 105 (seealso paragraph60). 

: 126) In order to prevent any one organ or 

• ue from receiving a total dose which could 

^•r.tribute significantly to the induction of 

non-stochastic effects, an overriding annual 

d-.v c-equivalent limit of 50 mSv should apply. 

;

 "•.!•; limit is considerably lower than the 

, esponding limits recommended for pre-

• e::>;on of non-stochastic effects after occu-

; vonal exposure. The intention is to ensure 

: ::: the longer exposure period and the 

;-.vcrical difficulties in controlling the total 

. posure from all sources will not result in 

::-. vjhold doses for non-stochastic effects 

i.-.u reached. The weighting procedure 

commended in paragraph 125 will generally 

. provide the necessary limitation also for non-

. :i-.!chastic effects, but the special limitation is 

...needed for the skin and the lens ofthe eye. 

127) In the calculation of the dose equivalent incurred by members ofthe public from 

V":;ke of radionuclides, account must be 

;u!:cn of differences in organ size or metabolic 

characteristics of children. Data on such 

differences may be found in the report of the 

•ask group on Reference Man (ICRP 

Fublication23). 

(128) As with workers (see paragraph 102) 

an increase in the average dose to members of 

'die public could result from any large increase 

"i die number of sources of exposure, even 

diough each satisfactorily met the criteria of 

'•'istification and optimization (see paragraphs 68-76) and caused no exposures above 

die recommended limits. National and 

regional authorities should therefore keep 

under surveillance the separate contributions 

1

 rom all practices to the average exposure of 

!

'ie whole population so as to ensure that no 

M

"gle source or practice contributes an 

''"justified amount to the total exposure, and 

'''at no individual receives undue exposure as 

•

l

 result of membership of a number of critical 

groups. 

/: xposure of populations 

C29) In its previous recommendations the 

Commission suggested a genetic dose limit, 

although it expressed reservations about 

proposing generally applicable dose limits for 

populations. It has become increasingly clear 

that the previously suggested level is not likely 

to be reached, and it is very improbable that 

responsible authorities would permit the 

average dose equivalent in a population to 

reach values that are more than smail fractions of the former genetic dose limit of 5 rem 

in 30 years. Therefore, continuance of the 

former genetic dose limit could be regarded as 

suggesting the acceptability of a higher 

population exposure than is either necessary 

or probable, and a higher risk than is justified 

by any present or easily envisaged future 

development. Furthermore, knowledge 

gained over the past two decades indicates 

that genetic effects, while important, are 

unlikely to be of overriding importance, and 

would need to be related to the sum of all 

other effects. 

(130) In these recommendations, therefore, 

the Commission does not propose dose limits 

for populations. Instead it wishes to emphasize that each man-made contribution to 

population exposure has to be justified by its 

benefits, and that limits for individual 

members of the public refer to the total dose 

equivalent received from all sources (except as 

already noted). The limit for irradiation of a 

whole population is thus clearly seen as the 

total reached by a summation of minimum 

necessary contributions, and not as a permissible total apparently available for apportionment. Consideration of the principles 

enunciated in paragraphs 117-125, together 

with the Commission's system of dose limitation, is likely to ensure that the average dose 

equivalent to the population will not exceed 

0.5 mSv per year. 

(131) In any cost-benefit assessment of a 

given practice (see paragraphs 60 and 68-76) 

the specification of the collective dose 

equivalent is a relatively straightforward procedure if the dose equivalent is limited to the 

population that shares the benefit of the 

source. If the exposure will involve other 
P.33 

26 RECOMMENDATIONS OF THE ICRP 

populations (or groups,, etc.} the total collective dose equivalent should'be kept below that 

which would have applied had the costbenefit assessment been confined to the 

population that receives the benefit. 

(132) For the purposes envisaged in paragraph 128 it would be useful to develop longterm forecasts of the trend of the various contributions to the total collective dose equivalent delivered from various sources of 

exposure. This would facilitate discussions of 

the appropriate national and international 

arrangements in regard to justification for 

particular contributions to population 

exposures. Contributions that are not 

primarily controllable nationally, or on an 

agreed regional basis, call for international 

agreement on levels of exposure or collective 

dose equivalents from various sources. In 

order to achieve these objectives, such 

authorities may find it appropriate to apply 

collective dose-equivalent limits for various 

practices or sources of exposure. 

A ccidents and emergencies 

(133) Under conditions in which accidental 

exposures occur, questions arise as to what 

remedial actions may be available to limit the 

subsequent dose. In.such cases, the hazard or 

social cost involved in any remedial measure 

must be justified by the reduction of risk that 

will result. Because of the great variability of 

the circumstances in which remedial action 

might be considered, it is not possible for the 

Commission to recommend "intervention 

levels" that would be appropriate for all 

occasions. However, with certain types of 

accident that are to some extent foreseeable it 

may be possible to gauge, by an analysis of the 

costs of the accident and of remedial action, 

levels below which it would not be appropriate 

to take action. 

(134) The decision to initiate remedial 

action will have to take account of the particular circumstances that prevail. In general it 

will be appropriate to institute countenneasures only when their social cost and risk will be 

less than those resulting from further 

exposure. Nevertheless, at the operational 

level (at a reactor establishment, for example) 

those responsible for the health and safety of 

workers, and of individuals outside the establishment, will need to have an emergency 

plan, including dose levels at which various 

countenneasures would have to be considered. The setting of such levels for particular circumstances is considered to be the 

responsibility of the national authorities. (See 

also section G.) 

(135) It has been indicated in paragraph 81 

that the Commission's dose-equivalent limits 

are agreed values, established so as to make it 

possible to plan and design operations 

involving foreseen but acceptable radiation 

exposures. These limits are intended to apply 

only to those conditions where the source of 

exposure is under control, and relate to 

average workers without taking any accouni 

of age or child expectancy. The Commission's 

recommended limits are set at a level which is 

thought to be associated with a low degree of 

risk; thus, unless a limit were to be exceeded 

by a considerable amount, the risk would still 

be sufficiently low as not to warrant such 

countenneasures as would themselves involve 

significant risks or undue cost. It is therefore 

clear that it is not obligatory to take remedial 

action if a dose-equivalent limit has been or 

might be exceeded (see section G). 

F. GENER 

(136) The recommenda 

the report deal with the g 

operational radiation pr 

initial conception of a 

exposure to ionizing radi 

limitation of such exp 

operations, to the proc 

cases of accident or emerg 

(137) As has been statec 

is convenient to define thr 

to which these recommenc 

the exposure of individt 

their work; 

the exposure of indivi 

medical examination or 

other exposures of indiv 

These points are discussei 

G. 

(138) More detailed re< 

some aspects appear in 

committees (see Referen 

judgment is called for in tl 

these recommendations. 

(139) Responsibilities fc 

priate radiation proteci 

employers, the statutory 

ities, the manufacturers 

products giving rise to r 

and, in some cases, the exj 

management of an institi 

all the necessary facilities f 

of the operations unde 

particular, it should desig 

special duties for protectio: 

of radiation protection teat 

(140) All proposed inst 

operations, all changes ir 

tions and operations, and a 

products containing radio; 
CRP 

accident and of remedial action, 

which it would not be appropriate 

>n. 

e decision to initiate remedial 

>ave to take account of the particstances that prevail. In general it 

opriate to institute countermeaslen their social cost and risk will be 

those resulting from further 

Nevertheless, at the operational 

actor establishment, for example) 

nsible for the health and safety of 

d of individuals outside the estab-

/ill need to have an emergency 

ling dose levels at which various 

sures would have to be con-

: setting of such levels for particutances is considered to be the. 

ty of the national authorities. (See 

G.) 

as been indicated in paragraph 81 

nmission's dose-equivalent limits 

alues, established so as to make it 

> plan and design operations 

?reseen but acceptable radiation 

These limits are intended to apply 

ie conditions where the source of 

• under control, and relate to 

rkers without taking any account 

Id expectancy. The Commission's 

ed limits are set at a level which is 

7e associated with a low degree of 

mless a limit were to be exceeded 

:rable amount, the risk would still 

itly low as not to warrant such 

sures as would themselves involve 

isks or undue cost. It is therefore 

is not obligatory to take remedial 

Jose-equivalent limit has been or 

.eeded (see section G). 

RECOMMENDATIONS OF THE ICRP 

GENERAL PRINCIPLES OF OPERATIONAL 

RADIATION PROTECTION 

INTRODUCTION 

(136) The recommendations of this part of 

;ne report deal with the general principles of 

operational radiation protection, from the 

initial conception of a proposal involving 

exposure to ionizing radiations, through the 

limitation of such exposures in normal 

operations, to the procedures required in 

•. ases of accident or emergency. 

(137) As has been stated in paragraph 83, it 

is convenient to define three types of exposure 

to which these recommendations apply: 

the exposure of individuals in the course of 

their work; 

the exposure of individuals due to their 

medical examination or treatment; and 

other exposures of individuals. 

These points are discussed further in section 

G. 

(138) More detailed recommendations on 

some aspects appear in reports of ICRP. 

committees (see References). Professional 

judgment is called for in the application of all 

these recommendations. 

(139) Responsibilities for achieving appropriate radiation protection fall on the 

employers, the statutory competent authorities, the manufacturers and the users of 

products giving rise to radiation exposure 

and, in some cases, the exposed persons. The 

management of an institution must provide 

all the necessary facilities for the safe conduct 

of the operations under its control. In 

particular, it should designate persons with 

special duties for protection, such as members 

of radiation protection teams. 

(140) All proposed installations and new 

operations, all changes in existing installations and operations, and all new or modified 

Products containing radioactive materials or 

27 

emitting ionizing radiation, s&nmffld be 

examined at the design stage froamtffliepDintof 

view of restricting the resulting «naaE{pational 

and general exposure. Such exaimrnimions can 

often be carried out by comgranissni with 

detailed technical standards prqpansi taking 

into account the recommendattiians of the 

Commission. 

(141) Before commissioningannihstaiUlation, 

starting an operation or distributtongaipitoduct, 

it should be established that tUneiinSfflillation, 

operation or product conforms \wtiih the 

approved proposals and that, the ^jEpnropriate 

radiation protection requiremenfls Hmts been 

met. In the case of installations audi operations, there should be contirtniting dtacks on 

the effectiveness of the organnizifliiiimal arrangements made to achieve praflseaBiom, and 

on the availability and applicaflmnn off appropriate working instructions. 

(142) The assessment of exposure toff individuals or groups, carried out toy saalkiulation 

or measurement, is an essential©mnpsiment of 

the procedures for restricting esqpssjme and 

for intervention (see paragraph MS)). The 

emphasis at the design and early aparational 

stages is on predictive assessraennlts;Bm>U„ where 

necessary, is confirmed by maraianriimg(during 

subsequent operations. Predidtine 'assessments are also needed in the [planning of 

intervention procedures but, im aatidition, 

monitoring carried out during saaanmBU operations will often provide the feasis for any 

decisions to intervene. 

(143) Intervention is the teran lusadl when 

steps have to be taken to depart tfiwmm mormal 

operating procedures in abnonmrilttitiua'tions, 

including accidents. Its aim is tt® mesttr'ict the 

exposure of individuals and to iminhriize the 

consequences of unavoidable tesqpsDsures. 
P.35 

28 RECOMMENDATIONS OF THE ICRP 

Intervention usually involves action to regain 

control oftheabnormal situation and countermeasures applied to individuals or their 

environment. The broad structure of the 

procedures for intervention should be the 

subject of advanced planning, taking into 

account the probability as well as the consequences of the various situations for which 

intervention might be required. The details 

may need to be settled in the light of the 

prevailing circumstances. 

PROTECTION STANDARDS 

(144) It is important to distinguish between 

distinct types of protection standards: basic 

limits (dose-equivalent limits and secondary 

limits), derived limits, authorized limits and 

reference levels. 

Limits 

(145) The dose-equivalent limits (see paragraphs 103 and 104, 119 and 126) apply to the 

dose equivalent or, where appropriate, the 

committed dose equivalent, in the organs or 

tissues of the body of an individual or, in the 

case of exposure of the population, to the 

average of one of these quantities over a 

group of individuals. 

(146) Secondary limits are given for external 

irradiation and for internal irradiation. In the 

case of external irradiation of the whole body 

the secondary limit applies to the maximum 

dose equivalent in the body at depths below 

1 cm (see paragraph 108). The secondary 

limits for internal exposure are the annual 

limits of intake by inhalation or ingestion (see 

paragraph 109). These limits of intake relate 

to adult Reference Man. When, however, a 

critical group of the public differs substantially in biological characteristics from 

Reference Man, it may be appropriate to take 

account of such differences (see also paragraph 127). 

(147) In practical radiation protection, it is 

often necessary to provide limits associated 

with quantities other than dose equivalent, 

committed dose equivalent, or intake, and 

relating, for example, to environmental 

conditions. When these limits are related to 

the basic limits by a defined model of the 

situation and are intended to reflect the basic 

limits, they are called derived limits. Derived 

limits may be set for quantities such as doseequivalent rate in a workplace, contamination of air, contamination of surfaces and 

contamination of environmental materials. 

The accuracy of the link between derived 

limits and basic limits depends on the realism 

of trie model used in the derivation. 

(148) Limits laid down by a competent 

authority or by the management of an institution are called authorized limits. These 

should, in general, be below derived limits 

though, exceptionally, they may be equal to 

them. The process of optimization may be 

used in the establishment of authorized limits 

and they apply only in limited circumstances. 

It is important that any such limitations 

should be clearly laid down. Where an 

authorized limit exists it will always take 

precedence over a derived limit. 

Reference levels 

(149) Reference levels may be established 

for any of the quantities determined in the 

course of radiation protection programs, 

whether or not there are limits for these 

quantities. A reference level is not a limit and 

is used to determine a course of action when 

the value of a quantity exceeds or is predicted 

to exceed the reference level. The action to be 

initiated may range from simply recording the 

information, through investigations into 

causes and consequences, up to intervention 

measures. It is important to define the general 

scope of iWs action whei 

cnce level Hie most com 

ence level ane 'recording 

levels andiiaiKrvention lev 

(150) Manny measurerm 

oring programs show rest 

to be of nmffisrest and sue 

discarded without .being i 

helpful to drifine a forma 

dose eqpreaiflent .or intak 

result is ffiF sufficient in 

recording amid keeping. Oi 

be covecd%- the simple 

were a l Wmv fee defin 

Theseumrainorded results > 

zero for assessing annual 

intake for tihe purposes o 

tion. TM$ abroach resul: 

simplifkaanmn of the recc 

results. 

(151) Immestigation leve 

values tsS-t&ose equivalen 

(153) TBa application 

optinrnannnni io tbe restr: 

and, inpamniQular, to the sc 

protectBKam, acquires a case 

situatkms.. Um practice, a 

protecuMHm.iarrategies.is defi 

radiatfrnmesqposure and the 

going firaamn cone strategy tc 

evaluated. Both variatior 

pressed im comparable tei 

stage itlaatt poses \the greatc 

also psr,agii^phs 72-76). 

(154)A$sfatted:in paragr, 

assume tifaatttihe detriment t 

tional to flflneceoliective dos 

exposed ©nnu$p, •but other c 

detriment mnay bs rnfluer 

highest utaecaquivalent anc 

the rafcmtnmniBship between t 

relevant intriit. Two extre 

worth- eHnMnaaering. In the f 
CRP 

• probability as well as the consethe various situations for which 

1 might be required. The details 

to be settled in the light of the 

ircumstances. 

IDS 

mits by a defined model of the 

d are intended to reflect the basic 

are called derived limits. Derived 

je set for quantities such as doserate in a workplace, contaminacontamination of surfaces and 

ion of environmental materials. 

cy of the link between derived"' 

asic limits depends on the realism 

.1 used in the derivation, 

nits laid down by a competent 

by the management of an institualled authorized limits. These 

general, be below derived limits 

eptionally, they may be equal to 

process of optimization may be 

•stablishment of authorized limits 

ply only in limited circumstances, 

tant that any such limitations 

clearly laid down. Where an 

limit exists it will always take 

?ver a derived limit. 

?vels 

erence levels may be established 

the quantities determined in the 

radiation protection programs, 

not there are limits for these 

\ reference level is not a limit and 

etermine a course of action when 

a quantity exceeds or is predicted 

e reference level. The action to be 

y range from simply recording the 

i, through investigations into 

consequences, up to intervention 

: is important to define the general 

RECOMMENDATIONS OF THE ICRP 29 

scope of this action when defining the reference level. The most common forms of reference level are recording levels, investigation 

levels and intervention levels. 

(150) Many measurements made in monitoring programs show results that are too low 

to be of interest and such results are often 

discarded without being recorded. It is often 

helpful to define a formal recording level for 

uose equivalent or intake above which the 

esult is of sufficient interest to be worth 

recording and keeping. Other results can then 

be covered by the simple statement that they 

vere all below the defined recording level. 

These unrecorded results should be treated as 

/c:o for assessing annual dose equivalent or 

iiv.ake for the purposes of radiation protec-

- tion. This approach results in a considerable 

simplification of the records of monitoring 

• results. 

(151) Investigation levels can be defined as 

vatues of dose equivalent or intake above 

which the results are considered sufficiently 

important to justify further investigations. 

For any defined type of measurement it is 

possible to establish a derived investigation 

level such that a measured result below the 

derived investigation level will, with reasonable certainty, correspond to a value of dose 

equivalent or intake below the relevant 

investigation level (see paragraphs 178-181). 

(152) Although the details of intervention 

will depend on the situation prevailing at the 

time, experience has shown that it is often 

useful to have pre-established intervention 

levels so that if the value of a quantity does not 

exceed or is not predicted to exceed the intervention level, then it is highly improbable that 

intervention will be required. Because intervention is liable to interfere with normal 

operation or, in some cases, to disrupt the 

normal chain of responsibilities, it should nut 

be undertaken lightly. 

OPERATIONAL OPTIMIZATION 

(153) The application of the process of 

optimization to the restriction of exposure 

and, in particular, to the selection of levels of 

protection, requires a case-by-case review of 

situations. In practice, a series of radiation 

protection strategies is defined. The change in 

radiation exposure and the differential cost of 

going from one strategy to the next are then 

evaluated. Both variations need to be expressed in comparable terms, and it is this 

stage that poses the greatest difficulties (see 

also paragraphs 72-76). 

(154) As stated in paragraph 24 it is usual to 

assume that the detriment to health is proportional to the collective dose equivalent in the 

exposed group, but other components of the 

detriment may be influenced more by the 

highest dose equivalent and, in particular, by 

'he relationship between this value and the 

relevant limit. Two extreme situations are 

w

orth considering. In the first, the detriment 

to health in the exposed group is the predominant component of the total detriment 

and the required comparison is the differential 

change in the cost of protection strategies sind 

the corresponding differential change of the 

collective dose equivalent. The second 

extreme situation is where the detriment to 

health is likely to be very small, for example 

where the numbers of individuals are extremely limited. Optimization in this case involves 

the highest individual dose equivalent as 

opposed to the collective dose equivalent and 

it is necessary to take account of exposure 

contributions from procedures other than 

that under review. 

(155) Some exposures are due to minor 

mishaps and it is then necessary to consider 

not only the level of exposure but also its 

probability, or more simply, to look at the 

long-term average of the exposure of individuals resulting from both continuous and 
P.37 

30 RECOMMENDATIONS OF THE ICRP 

intermittent exposure. This technique allows 

choices to be made between the resources to 

be devoted to the reduction of routine exposures and those to be devoted to the avoidance 

of minor mishaps. 

(156) It would also be convenient to identify 

the possible additional benefit that would 

result from the provision of monitoring 

resources in addition to the minimum 

necessary to demonstrate compliance with the 

optimized level of exposure. However, it is 

usually very difficult to quantify this kind of 

benefit, and consequently decisions are based 

largely on judgment. 

(157) As most forms of intervention involve 

some detriment, the optimal-method of intervention depends on a balance between the 

detriment caused by the intervention and the 

benefit expected by the reductions of dose 

achieved by the intervention. Such a balance 

necessarily depends on local circumstances at 

the time of the situation calling for intervention, but preliminary planning should be done 

in advance on a contingency basis. 

(158) A considerable contribution is made 

to radiation protection by the use of technical 

standards and specifications. The case-bycase optimization of widely used equipment is 

not appropriate because it would nullify the 

advantages of standardization and would 

cause a net social loss. Optimization should, 

however, play a part in the setting of such 

standards and specifications and in their 

subsequent application. 

(159) When appropriate data for true optimization are lacking, a much cruder process 

may be adopted. This process consists of 

applying a fairly arbitrary reduction factor to 

a limit, or of applying similarly arbitrary 

safety factors in plant design. The resulting 

exposures may then be either higher or lower 

than the optimum value. 

APPLICATION TO THE DIFFERENT TYPES 

OF EXPOSURE 

OCCUPATIONAL EXPOSURE 

(160) The main responsibility for the protection of workers rests with the normal chain 

of management in an institution possessing 

any radiation source that causes exposure of 

workers. It is necessary to identify technically 

competent persons to provide advice on all 

relevant aspects of radiation protection, both 

inside and outside the institution, and to provide such technical services as are needed in 

the application of the appropriate recommendations for radiation protection. 

Conditions of work 

(161) For the purposes of this report occupational exposure comprises all the dose 

equivalents and intakes incurred by a worker 

".during periods of work (excluding those due 

to medical and natural radiation). The scale 

.and form of the problems of radiation 

protection of workers vary over very wide 

-ranges, and there are practical advantages in 

•introducing a system of classification of 

conditions of work. Conditions of work can 

•be divided into two classes: 

Working Condition A: this describes 

conditions where the annual exposures 

might exceed three-tenths of the doseequivaleai limits; 

WorkingCondition B: this describes conditions where it is most unlikely that the 

annual exposures will exceed three-tenths 

of thedose-equivalent limits. 

The value of three-ten 

for occupationai expos 

level used in the organi; 

is not a limit. Where t 

nccted with the work, a; 

premises not containin: 

giving rise to the ex 

condition should be sue 

cable to members of the 

(162) The main aim 

Working Condition / 

workers who might oth 

the dose-equivalent li 

individual monitoring s 

can be restricted if ne 

Condition B, individu 

necessary, although it 

carried out as a method 

conditions are satisfactc 

(163) The practical 

system of classification > 

is greatly simplified by 

corresponding system 

workplaces. The minim 

define controlled are: 

operation would give ri: 

tion A and to which a 

demarcation of control 

on the operational situe 

be convenient to use 

boundaries. The control 

case be large enough to 

that the annual dose-ec 

outside the controlled a 

tenths of the limits. 

(164) It is sometimes c 

further class of work] 

"supervised area", ai 

chosen so as to make it i 

annual dose equivalent 

vised area will exceed or, 

(165)ThereisnosimpI 

the classification of are 

tion of working cone 

classification of areas ta 

time spent by workers i; 

course of the year and b. 

rarely uniform througho 

1 I 
Hv-J 

RP 

he situation calling for interveniminary planning should be done 

1 a contingency basis, 

msiderable contribution is made 

protection by the use of technical 

id specifications. The case-byation of widely used equipment is 

iate because it would nullify the 

of standardization and would 

ocial loss. Optimization should, 

iy a part in the setting of such 

ad specifications and in their 

pplication. 

n appropriate data for true optilacking, a much cruder process 

pted. This process consists of 

irly arbitrary reduction factor to 

3f applying similarly arbitrary 

•s in plant design. The resulting 

iy then be either higher or lower 

num value. 

:RENT TYPES 

RE 

is of work (excluding those due 

id natural radiation). The scale 

>f the problems of radiation 

f workers vary over very wide 

here are practical advantages in 

a system of classification of 

" work. Conditions of work can 

o two classes: 

Condition A: this describes 

where the annual exposures 

-'cd three-tenths of the doselimits; 

ondition B: this describes condie it is most unlikely that the 

osures will exceed three-tenths 

equivalent limits. 

RECOMMENDATIONS OF THE ICRP 31 

The value of three-tenths of the basic limits 

for occupational exposure is thus a reference 

level used in the organization of protection. It 

is not a limit. Where the exposure is unconnected with the work, and where the work is in 

premises not containing the radiation sources 

giving rise to the exposure, the working 

condition should be such that the limits appliable to members of the public are observed. 

(162) The main aim of the definition of 

working Condition A is to ensure that 

vorkers who might otherwise reach or exceed 

the dose-equivalent limits are subject to 

individual monitoring so that their exposures 

can be restricted if necessary. In Working 

Condition B, individual monitoring is not 

necessary, although it may sometimes be 

carried out as a method of confirmation that 

conditions are satisfactory. 

(163) The practical application of this 

• .stem of classification of working conditions 

:> greatly simplified by the introduction of a 

corresponding system of classification of 

workplaces. The minimum requirement is to 

define controlled areas where continued 

operation would give rise to Working Condition A and to which access is limited. The 

demarcation of controlled areas will depend 

on the operational situation and it will often 

be convenient to use existing structural 

boundaries. The controlled area should in any 

case be large enough to make it most unlikely 

that the annual dose-equivalents to workers 

outside the controlled area will exceed threetenths of the limits. 

(164) It is sometimes convenient to specify a 

further class of workplace. It is called a 

"supervised area", and has a boundary 

chosen so as to make it most unlikely that the 

annual dose equivalents outside the supervised area will exceed one-tenth of the limits. 

(165) There is no simple parallelism between 

the classification of areas and the classification of working conditions, because the 

classification of areas takes no account of the 

time spent by workers in the area during the 

eourse of the year and because conditions are 

r

arcly uniform throughout an area. 

(166) In order to simplify the arrangements 

for medical supervision and for individual 

monitoring, it is usual to classify individual 

workers. In principle, this can be done in 

terms of the class of working conditions in 

which they operate, but in practice it almost 

always has to be done in terms of the areas 

where they work, the type of work done and, 

if this can be forecast with sufficient reliability, the time to be spent in the area. 

Provisions.for restricting exposure 

(167) As far as is reasonably practicable, 

the arrangements for restricting occupational 

exposure should be those applied to the source 

of radiation and to features of the workplace. 

The use of personal protective equipment 

should in general be supplementary to these 

more fundamental provisions. The emphasis 

should thus be on intrinsic safety in the workplace and only secondarily on protection that 

depends on the worker's own actions. 

(168) Access to controlled areas should be 

restricted, at least by the use of warning signs. 

Inside controlled areas it may sometimes be 

necessary to define regions where compliance 

with the relevant limits can be achieved only 

by limiting the time spent in the region or by 

using special protective equipment. The 

access of workers to controlled areas should 

be limited to those who are assigned to the 

area and to others who have been authorized 

to have access. The access of workers to 

supervised areas should be the subject of local 

operating instructions. Visitors, either 

workers or members of the public, should be 

admitted to workplaces only with the 

approval of an appropriate level of the 

management responsible for the workplace. 

(169) External exposure may be restricted 

by the use of shielding, distance and limitation of time of exposure. Shielding produces 

intrinsically safe conditions in the workplace. 

Distance and limitation of time of exposure 

require the careful training and supervision of 

workers. Complete protection is afforded by 

the use of "closed" installations providing 
P.39 

32 RECOMMENDATIONS OF THE ICRP 

virtually complete shielding.for the radiation 

source and effectively preventing access. 

However, the failure of such equipment as 

interlock systems may cause excessive 

exposure. Operating procedures should therefore include routine checks of such systems. 

(170) Contamination by radioactive 

materials may be restricted by containment 

and cleanliness. Containment, which provides intrinsic safety, consists of a series of 

barriers, their number being a function of the 

potential hazards involved. Total containment is not always justified and partial containment may be sufficient provided that it is 

supplemented by a high standard of cleanliness. Ventilation plays a significant part in 

both containment and cleanliness. When 

contamination of the workplace cannot be 

excluded, personal protective equipment has 

a part to play in the protection of workers. 

(171) Although the Commission gives 

recommendations relating to planned special 

exposures to internal contamination (see 

paragraph 113) the use of protective equipment should make such exposures unnecessary. 

(172) All workers who may have access to 

supervised or controlled areas should be 

properly trained and given appropriate information about the hazards-of their work and 

about the precautions they should take to 

protect themselves. They should be made 

aware of the importance of complying with 

the working instructions. 

Monitoring of exposure 

(173) Workers designated as operating in 

Working Condition A should be the subject 

of individual assessment of dose equivalent, 

committed dose equivalent or intake, as the 

case may be. This consists of individual 

monitoring for external irradiation and for 

internal contamination as appropriate. In 

some cases it will be necessary to use indirect 

methods. An individual assessment of exposure is not required for workers designated as 

working in Working Condition B. It is sufficient to assess the conditions in the working 

environment, following the principles and 

recommendations set out in ICRP Publication 

12. 

(174) Monitoring programs should be 

designed to meet clearly defined objectives: 

routine monitoring, associated with continuing operations, monitoring of an operation, 

applied to a particular operation, and special 

monitoring in an actual or suspected abnormal situation. In addition to the primary 

aims, most monitoring programs have 

supplementary functions. The programs 

should be reviewed both periodically in the 

light of experience, and in the event of any 

major modification of the installation or the 

operations, to ensure that they continue to 

meet their objectives. 

The use of protection standards to interpret 

monitoring results. (175) Use can be made of 

derived limits or authorized limits in the 

application of individual monitoring programs. Such limits are essential in the monitoring of operations where, in general, only part 

ofthe dose-equivalent limit or secondary limit 

can be committed to the operation. 

(176) Only in a few circumstances can the 

results of programs of monitoring of the 

workplace be used to estimate the dose 

equivalents or intakes of individual workers. 

The use of derived or authorized limits is 

essential in the interpretation of environmental monitoring programs. 

(177) A substantial part of all monitoring 

programs is confirmatory in nature and, given 

satisfactory results, no further action needs to 

be taken. In these circumstances there is a 

possibility that the occasional significant 

result will be overlooked, unless use is made 

of investigation levels and derived investigation levels. The initial action to be taken when 

a result exceeds an investigation level should 

be determined in advance. 

(178) It is possible to give general guidance 

on investigation levels for individual monitoring that applies in a large number of situations. Since there is no Commission recommendation on in 

Working Conditio; 

unlikely that the e? 

tenths of the appi 

secondary or derive 

priate to use

 rhis 

setting investigatic 

monitoring. Howe\ 

to be useful, has to 1 

measurement, not 

equivalent or intak 

appropriate to base 

the fraction of three 

ponding to the frac 

individual monitor 

Corresponding dei 

can then be deduced 

measured. 

(179) Somewhat 

apply in the setting 

programs of speci 

monitoring is assoc 

though not neces; 

principle, the choie 

depends on the exp 

occasions on which 

during the year. In 

Commission recom 

tion level should co: 

of the annual dos 

level bears tha saint 

equivalent li.nit as 

level for routine nv 

that events requiri 

monitoring may oc 

individual about six 

(180) Investigatic 

monitoring will de] 

form of the monitc 

type of investigatic 

common form of i 

monitoring of wo 

expected consistenc 

conditions. 

(181) Although it 

able for initiating i: 

situations, it may 

dose equivalents a 

The Commission re 
ions in the working 

the principles and 

n ICRP Publication 

>grams should be 

defined objectives: 

.iated with continu-

;g of an operation, 

eration, and special 

i or suspected abtion to the primary 

: programs have 

s. The programs 

periodically in the 

in the event of any 

c installation or the 

it they continue to 

•mdards to interpret 

Use can be made of 

ized limits in the 

i monitoring prontialinthemonitorn general, only part 

it or secondary limit 

>cration. 

cumstances can the 

monitoring of the 

estimate the dose 

individual workers, 

uthorized limits is 

tation of environrris. 

t of ail monitoring 

in nature and, given 

ther action needs to 

nstances there is a 

asional significant 

unless use is made 

1 derived investigam to betaken when 

gation level should 

• e general guidance 

ndividual monitor-. 

c number of situaommission rccomRECOMMENDATIONS OF THE ICRP 33 

mendation on individual monitoring in 

Working Condition B (i.e. where it is most 

unlikely that the exposure will exceed threetenths of the appropriate dose equivalent, 

secondary or derived limits) it is often appropriate to use this figure of three-tenths in 

setting investigation levels for individual 

monitoring. However, an investigation level, 

to be useful, has to be set in relation to a single 

measurement, not the accumulated dose 

equivalent or intake in a year, and it is most 

appropriate to base the investigation level on 

the fraction of three-tenths of the limit corresponding to the fraction of a year to which the 

individual monitoring measurement refers. 

Corresponding derived investigation levels 

can then be deduced for the quantities directly 

. measured. 

.(179) Somewhat different considerations 

apply in the setting of investigation levels for 

programs of special monitoring. Here the 

monitoring is associated with a single event, 

though not necessarily a unique one. In 

principle, the choice of an investigation level 

depends on the expectation of the number of 

occasions on which similar events will occur 

during the year. In ICRP Publication 10, the 

Commission recommends that the investigation level should correspond to one-twentieth 

of the annual dose-equivalent limits. This 

level bears the same relationship to the doseequivalent limit as does the corresponding 

level for routine monitoring, if it is assumed 

that events requiring a program of special 

monitoring may occur in relation to a single 

individual about six times in a year. 

(180) Investigation levels for other types of 

monitoring will depend on the objectives and 

form of the monitoring program and on the 

type of investigation to be carried out. One 

common form of investigation level for the 

monitoring of workplaces is based on the 

expected consistency of results during normal 

conditions. 

(181) Although investigation levels are suitable for initiating investigations into specific 

situations, it may be convenient to record 

dose equivalents at somewhat lower levels. 

The Commission recommends that recording 

levels should be based on an annual dose 

equivalent or intake of one-tenth of the 

annual dose-equivalent limit or intake limit. 

(182) For the special case of monitoring of 

skin, two situations occur in routine practice. 

For external radiation a dose equivalent is 

measured by one or two dosemeters and the 

results are treated as representative of the 

whole, or of substantial areas, of the skin. No 

problem of averaging then arises and the 

results are related directly to the relevant 

dose-equivalent iimit. In the second situation, 

the irradiation results from surface contamination on the skin. This is never uniform and 

occurs preferentially on certain parts of the 

body, notably the hands. However, it does 

not persist over many weeks and does not 

always occur again at exactly the same places. 

For routine purposes, it is adequate to regard 

the contamination as being averaged over 

areas of about 100 cm2. Routine monitoring 

for skin contamination should therefore be 

interpreted on this basis and the limit applied 

to the average dose equivalent over 100 cm2. 

(183) In accidents or suspected accidents, 

more detailed information should be sought 

on the distribution of absorbed dose, dose 

equivalent or contamination. An estimate 

should be made of the average dose equivalent 

over 1 cm2 in the region of the highest dose 

equivalent. This dose equivalent should then 

be compared with the dose-equivalent limit. If 

the dose distribution is extremely nonuniform, as is that from very small particles in 

contact with the skin, the local distribution of 

absorbed dose should be assessed and used to 

predict possible local skin reactions. It is 

inappropriate, however, to relate such localized absorbed doses to the absorbed doses 

corresponding to the dose-equivalent limit. 

Medical surveillance 

(184) The medical surveillance of workers 

exposed to radiation is based on the general 

principles of occupational medicine. It has the 

following aims: 

to assess the health of the worker; 

to help in ensuring initial and continuing 
P.41 

34 RECOMMENDATIONS OF THE ICRP 

compatibility between the health of the 

workers and the conditions of their work; 

to provide a base line of information useful 

in the case of accidental exposure or occupational disease. 

Deleterious effects cannot be unequivocally 

associated with exposures within the doseequivalent limits, and medical surveillance 

has no part to play in confirming the effectiveness of a radiation protection program. 

Medical surveillance may include both preoperational and routine examinations, the 

latter being determined mainly by the 

worker's general state of health and by the 

conditions of work. 

(185) Workers designated as operating in 

Working Condition A should be given a preoperational medical examination before 

starting this kind of work, though not necessarily before employment. One objective of 

this examination is the recognition of conditions or characteristics that limit the type of 

exposure to which the individual should be 

subjected. For these purposes, the physician 

needs information about the conditions of 

work, including details of the job description. 

(186) Following a preoperational examination, consideration should be given to the 

need for a continuing surveillance of the 

health of workers. If this is needed, the 

physician should have access to information 

held by the employing organization about the 

working conditions (e.g. job description and 

working environment) and about the state of 

health of workers (e.g. absences due to 

sickness). It is principally on the basis of this 

information that the frequency of any routine 

examinations should be decided. 

(187) The Commission considers that, with 

the present dose-equivalent limits, no special 

administrative arrangement is appropriate 

for workers as far as radiation risks are concerned. In particular, no special arrangement 

is required with respect to working hours and 

length of vacation. 

Intervention in abnormal situations 

(188) Arrangements should be made for 

dealing with abnormal situations, not only 

with respect to their detection and the assessment of dose or intake, but also with respect 

to the form of intervention that may have to 

be applied. The intervention levels and the 

appropriate actions for limiting exposure 

should be the subject of operating instructions.- Provision should be made for special 

medical surveillance and, if necessary, treatment following exposure substantially in 

excess ofthe dose-equivalent limits. 

(189) The emergency plans (which should, 

as far as practicable, be drawn up in advance) 

should have three clearly distinguished 

objectives. The first is to restrict exposures as 

far as is reasonably achievable and, in particular, to attempt to avoid exposures above the 

dose-equivalent limits. The second is to bring 

the situation back under control, and the third 

is to obtain information for assessing the 

causes and consequences ofthe event. 

(190) Although, by their nature, accidental 

exposures are not subject to control, their 

magnitude can to some extent be limited by 

intervention, especially if attention has been 

paid to this possibility during the design of 

installations and equipment and the preparation of operating instructions. 

(191) During the immediate course of a 

serious incident, urgent action to save life, to 

prevent injuries, or to prevent a substantial 

increase in the scale of the incident, may 

require that some workers be exposed in 

excess of the limits applicable to a planned 

special exposure. Such workers should be 

volunteers, and it is desirable that groups of 

workers likely to provide such volunteers 

should, as part of their normal training, 

receive information about risks involved in 

exposures above the limits. It will not normally 

be possible to control such exposures in detail, 

but substantial efforts should be made to provide an upper limit to the likely exposures. 

(192) Once the initial event has been brought 

under control, there remains the problem of 

remedial work. It will usually be appropriate 

to carry this out while maintaining compliance 

with the Commission's recommended limits 

but, exceptionally, i 

which the use of th< 

excessive expense or 

of people and rim 

then be given to the a 

izing a planned spec 

number of individt 

essential operations 

bedonein compliant 

(193) As a result 

individual workers i 

or contaminated. In 

ure, the immediate a 

to collect informa 

stances of the accide 

tests, with a view to 

the individuals who 

substantially above 

of contamination of 

intake by inhalatio: 

active substances, 

action is indicated. 

action is largely dete 

which it can be carrie 

to control contamii 

lowed to interfere wi 

quent treatment of 

medical attention foi 

will often have to 

grounds rather than 

(195) The term m 

the exposure of indi' 

examination or treat 

Most medical expos 

use of radiation for 

purposes, but some 

case of cardiac pa< 

active power source 

useful part and t 

adventitious. 

(196) The object: 

cedures are: 
RECOMMENDATIONS OF THE ICRP 

ituations, not only 

tion and the assessut also with respect 

n that may have to 

tion levels and the 

.limiting exposure 

operating instruce made for special 

if necessary, treate substantially in 

:nt limits. 

ans '(which should, 

awn up in advance) 

arly distinguished 

estrici exposures as 

able and, in particxposures above the 

e second is to bring 

mtroii, and the third 

for assessing the 

ftheesent. 

r nature, accidental 

t to control, their 

•ctent fee limited by 

attention has been 

ir'ing tthe design of 

nt and the prepara-

>ns. 

ediate course of a 

tion to save life, to 

event a substantial 

the incident, may 

..TS be exposed in 

cable to a planned 

/orkers should be 

ible that groups of 

e such volunteers 

normal training, 

t risks involved in 

I twill not normally 

exposures in detail, 

tld be made to pro-

:ely exposures, 

ithas been brought 

ins the problem of 

illy be appropriate 

lainingcompliance 

commended limits 

but, exceptionally, there may be situations in 

which the use of the limits would involve an 

excessive expense or an excessive involvement 

of people and time. Consideration should 

then be given to the appropriateness of authorizing a planned special exposure for a limited 

number of individuals to carry out various 

essential operations, leaving the remainder to 

be done in compliance with the limits. 

(193) As a result of abnormal situations, 

individual workers may be seriously exposed 

or contaminated. In respect of external exposure, the immediate action needed is essentially 

to collect information about the circumstances of the accident and to initiate medical 

tests, with a view to subsequent diagnosis, on 

the individuals who may have been exposed 

substantially above the limits. In some cases 

of contamination of skin or wounds, or of the 

intake by inhalation or ingestion of radioactive substances, immediate therapeutic 

action is indicated. The effectiveness of the 

action is largely determined by the speed with 

which it can be carried out. However, the need 

to control contamination should not be allowed to interfere with the first aid and subsequent treatment of individuals who require 

medical attention for other reasons. Decisions 

will often have to be made on qualitative 

grounds rather than on the basis of carefully 

made and interpreted monitoring measurements. It is particularly important in this 

respect that there should be a close working 

relationship between the management of the 

institution, the individuals with special 

responsibilities for radiation protection, and 

the medical staff, whether these be associated 

with the institution or the local hospital. It is 

essential that such working relationships be 

developed in advance. 

(194) The principal administrative arrangements to be made after an abnormal event are 

those concerned with initiating an investigation into the causes and consequences of the 

event and with reaching decisions about the 

need for any restriction on the future employment of those involved in the event. I f the dose 

or the intake of radioactive material exceeds 

twice the annual limit, the case should be 

subject to appropriate medical review. The 

worker may still be allowed to continue 

routine work if there is no objection from the 

medical standpoint, due account having been 

taken of previous exposure, health, age and 

special skills, as well as social and economic 

responsibilities. However, the event may have 

demonstrated characteristics in individuals 

indicating unsuitability for further employment in similar work. 

MEDICAL EXPOSURE 

(195) The term medical exposure refers to 

the exposure of individuals subject to medical 

examination or treatment involving radiation. 

Most medical exposure.is concerned with the 

use of radiation for diagnostic or therapeutic 

purposes, but sometimes, for example in the 

case of cardiac pacemakers using a radioactive power source, the radiations play no 

useful part and the exposure is merely 

adventitious. 

(196) The objectives of the medical procedures are: 

examinations or treatments directly associated with illness; 

systematic examinations undertaken for 

mass screening purposes or for periodic 

health checks; 

examinations forming part of the medical 

surveillance of workers or carried out for 

medico-legal or insurance purposes; 

examinations or treatment forming part of 

a medical research program. 
P.43 

36 RECOMMENDATIONS OF THE ICRP 

Examinations or treatments directly associassociated with illness 

(197) The decision as to whether an examination involving a certain radiation dose to a 

patient is justified is sometimes the responsibility of the referring physician, and sometimes of the practitioner who carries out the 

procedure.. In either case, however, it is 

imperative that the decision be based upon a 

correct assessment of the indications for the 

examination, the expected yield from the 

examination and the way in which the results 

are likely to influence the diagnosis and subsequent medical care ofthe patient. It is equally 

important that this assessment be made 

against a background of adequate knowledge 

of the physical properties and the biological 

effects of ionizing radiation. 

(198) I n therapeutic exposures, the absorbed 

doses to organs are in general very much 

higher and both the dangers of the exposure 

and the benefits of the treatment can be assessed more quantitatively. The decision can 

then be based on a balance between these 

aspects. It is also necessary to consider alternative therapeutic procedures and to compare 

their effectiveness and their dangers with 

those associated with radiological treatment. 

(199) While it is important that the decision 

to proceed with examinations or treatment 

involving exposure to radiations should take 

into account the dangers of such exposures, it 

is equally important that these dangers should 

not be overestimated, since this might lead to 

the rejection of justified examinations or 

treatments. 

Systematic examinations 

(200) Periodic health checks undertaken 

without reference to current illness may 

involve some radiological examinations. 

Their justification depends on the probability 

of obtaining useful information and the 

importance of this information for the individual's health. 

(201) For the systematic examinations used 

in mass screening, the justification should be 

based on a balance between the advantages 

implied for the individuals examined and for 

the population as a whole, together with the 

costs, including detriment, of the screening. 

In general, the advantages will depend on the 

yield of the screening procedure, the possibility of effective treatment of the cases 

detected and, for certain diseases, the advantages to the community of the control of the 

disease. The benefits of screening are not 

always the same for different groups making 

up the population and screening will often be 

justified only if it is limited to certain specified 

groups. The program should be subject to 

frequent examination to determine whether 

the yield in finding significant disease is sufficiently high to warrant its continuation. 

Examinations for occupational, medico-legal 

or insurance purposes 

(202) Examinations carried out to assess the 

fitness of an individual for work, to provide 

information for medico-legal purposes, or to 

assess the health of a subscriber to, or beneficiary of, an insurance may carry some direct 

or indirect advantages for the individual 

examined, but they also carry advantages for 

the employer, third parties and the insurer. 

All these aspects should be considered in 

assessing the justification of such examinations. 

Medical research 

(203) Examinations or treatment forming 

part of a medical research program sometimes 

involve direct benefits for the exposed individual and sometimes do not. When new and 

experimental methods of diagnosis or treatment are capable of benefitting the patients 

on whom they are tested, the justification for 

the procedures can be judged in the same way 

as for other medical exposures. Nevertheless, 

because of the experimental character of the 

procedures, they should be subject to thorough review. 

(204) The deliberate irradiation of persons 

for the purposes oi 

studies in which nc 

sons irradiated is i; 

when the exposure 

they may have, sho 

properly qualified; 

irradiation should 

consent of the aut 

institution where t 

place, as advised I 

body and subject to 

tions. The estimate 

should be explaine 

should be volumetheir free will. The 

rigorous should be 

conditions of secur: 

their capability of 

follows that the irr; 

of such studies, of c 

regarded as being 

true consent should 

expected radiaiion 

order of one-tentf 

limits applicable to 

public) and if valid i 

those legally respo 

The individuals exj 

tions obtain no d 

exposure and ir. is 

ensure that their d 

able, and thus to se 

ever, the magnitud 

ated with the exposi 

the state of health < 

and it is not possib 

applicability. App 

therefore be authc 

program. 

The optimization q 

(205) The Corr 

emphasize that care: 

would, in many case 

reduction of the do; 

ures, without impai 

general, the technic 

should allow: 
RECOMMENDATIONS OF THE ICRP 37 

een the advantages 

s examined and for 

:, together with the 

t, of the screening. 

; will depend on the 

ocedure, the possinent of the cases 

liseases, the advanf the control of the 

screening are not 

ent groups making 

eening will often be 

'. to certain specified 

ould be subject to 

determine whether 

:ant disease is suffiontinuation. 

ional, medico-legal 

ied out to assess the 

>r work, to provide 

gal purposes, or to 

•criber to, or benety carry some direct 

for the individual 

irry advantages for 

es and the insurer, 

be considered in 

of such examinatreatment forming 

Togram sometimes 

the exposed indiot. When new and 

diagnosis or treatTitting the patients 

he justification for 

ed in the same way 

ires. Nevertheless, 

al character of the 

>e subject to thordiation of persons 

for the purposes of those research and other 

studies in which no direct benefit to the persons irradiated is intended, in circumstances 

when the exposure is unrelated to any illness 

they may have, should only be undertaken by 

properly qualified and trained persons. Such 

irradiation should only be given with the 

consent of the authorities in charge of the 

institution where the irradiation is to take 

place, as advised by an appropriate expert 

body and subject to local and national regulations. The estimated risks of the irradiation 

should be explained to those involved, who 

should be volunteers fully able to exercise 

their free will. The higher the dose the more 

rigorous should be the requirements on the 

conditions of securing true volunteers and on 

their capability of understanding the risk. It 

• follows that the irradiation, for the purposes 

of such studies, of children and other persons 

regarded as being incapable of giving their 

true consent should only be undertaken if the 

expected radiation dose is low (e.g. of the 

order of one-tenth of the dose-equivalent 

limits applicable to individual members of the 

public) and if valid approval has been given by 

those legally responsible for such persons. 

The individuals exposed under these conditions obtain no direct benefit from their 

exposure and it is therefore necessary to 

ensure that their detriment remains acceptable, and thus to set authorized limits. However, the magnitude of the detriment associated with the exposure depends on the age and 

the state of health of the exposed individual 

and it is not possible to fix limits of general 

applicability. Appropriate limits should 

therefore be authorized for each research 

program. 

The optimization of exposure 

(205) The Commission wishes to reemphasize that careful attention to techniques 

would, in many cases, result in a considerable 

reduction of the dose due to medical procedures, without impairment of their value. In 

general, the techniques and equipment used 

should allow: 

the reduction of the doses received by 

tissues in the region of the body under 

examination to the minimum compatible 

with obtaining the necessary information 

in the particular patient; 

the delivery to the treated region of the 

body of a therapeutic dose the magnitude 

of which is most likely to ensure the required response; 

the limitation as far as practicable of the 

exposure of other parts of the body. 

(206) Because of the risk of radiation injury 

to any embryo or foetus, the possibility of 

pregnancy is one of the factors to be considered in deciding whether to make a radiological examination involving the lower 

abdomen in a woman of reproductive 

capacity. Although such an examination is 

least likely to pose any hazard to a developing 

embryo if carried out during the 10 day 

interval following the onset of menstruation, 

attention should always be paid to details of 

radiological technique that would ensure 

minimization of exposure to any embryo or 

foetus that may be present, whether or not the 

women is known to be pregnant. 

(207) Before prescribing an examination or 

investigation, the responsible practitioner 

should satisfy himself that the necessary 

information is not already available from 

other previous examinations and investigations. 

Professional training 

(208) The Commission wishes to emphasize 

the importance of including adequate training 

on radiation protection in the general education and training of individuals entering the 

medical and associated professions, since all 

those who enter these professions may be 

involved in prescribing procedures involving 

exposure to ionizing radiation. More 

thorough training in radiation protection is 

required by those planning to enter the field of 

radiology and by scientists and technicians 

assisting in the medical uses of radiation. 
P.45 

38 RECOMMENDATIONS OF THE ICRP 

(209) Recommendations and more detailed 

information on the protection of individuals 

subject to medical examinations or treatment 

and on the training of the medical profession 

are included in ICRP Publications 15, 16 and 

17. 

OTHER EXPOSURES 

(210) As a result of human activities, 

individuals in the population may be subject 

to exposure to many sources beyond those 

giving rise to occupational exposure and 

medical exposure. Exposure to this wide 

range of sources is considered in the following 

paragraphs. 

(211) The various contributions to other 

exposure may be grouped into broad categories to which the general principles of 

protection may apply but which call for 

different technical approaches: These 

categories are: 

exposure due to the dispersion in the environment of radioactive materials; 

direct exposure to radiation sources used in 

industry, medicine and research; 

exposure resulting from the use in everyday 

life of widely distributed products containing sources of ionizing radiation; 

exposure to natural sources of radiation 

and to practices iri everyday life that cause 

an increase in the level of dose resulting 

from the natural background of radiation; 

and 

exposure due to the use of radiation sources 

in teaching. 

The assessment of exposure 

(212) In order to apply the system of dose 

limitation to any practice involving such 

exposures, it is necessary to assess both the 

individual dose equivalents and the collective 

dose equivalents. For the purpose of comparing individual dose equivalents with the 

appropriate limits, the doses from the normal 

natural radiation background are not 

included (see paragraphs 89 and 90). 

(213) The assessment of individual dose 

equivalent has the aim of ensuring that the 

exposure of each individual remains within 

the appropriate limits and this assessment 

must therefore take into account not only the 

radiation resulting from the practice under 

consideration but also the total exposure 

resulting from all the practices that contribute 

to general exposure. The assessment of 

collective dose equivalent has as its main 

object the appraisal of the justification and 

optimization of the exposure. The assessment 

can therefore be carried out in relation to the 

proposed practice alone. 

(214) The exposure of individuals depends 

on a large number of factors, some related to 

their way of life and their use of the environment and others concerning their biological 

characteristics. It is not possible to evaluate 

these variables for each of the exposed 

individuals, but it is generally possible to 

identify within an exposed population smaller 

groups comprising individuals who are 

broadly comparable in respect of those 

characteristics that determine their exposure. 

(215) The dose equivalent to a specified 

organ or tissue in a given population group 

will usually be determined on the basis of a 

representative sample. The spread of the 

observed values will be an indication of the 

homogeneity of the sample, and thus of the 

group, and will provide a statistical basis for 

judging whether the group has been suitably 

defined. 

(216) It is often possible to identify 

population groups with characteristics 

causing them to be exposed at a higher level 

than the rest ofthe exposed population from a 

given practice. The exposure of these groups, 

known as critical groups, can then be used as a 

measure of the upp< 

doses resulting fron 

When several practii 

ficantly to the expos 

population, either si 

sively, th.e definitioi 

takeaccount of these 

(217) When the r 

time or the exposui 

mental contaminati 

collective annual dos 

a maximum over a p 

procedure continues 

maximum correspor 

ment of an equiiibr 

level resulting from i 

of the practice. It i 

average dose equival 

that should be comp; 

ing dose-equivalent I 

(218) It is also use) 

the dose-equivalent 

collective dose-eqi 

These are obtained b: 

the average dose-eq; 

the exposed popuk. 

dose-equivalent rat 

where each of these r; 

the application of a 

specified time, often 

tion that all reiev 

constant, the annue 

and the annual collei 

then reach equilibri 

dose-equivalent cc 

collective dose-equi 

year of practice. T: 

remain constant inci 

tion of the practice, 

ditions, the size of 

and the way people 

In some instances, 

assumed to continue 

allow for the annual c 

to reach equilibriu: 

sufficient to integrr 

equivalent rate over t 

as this integral is c 
RECOMMENDATIONS OF THE ICRP 39 

ie medical profession 

iblications 15,16 and 

t of individual dose 

of ensuring that the 

dual remains within 

and this assessment 

account not only the 

i the practice under 

the total exposure 

ctices that contribute 

The assessment of 

ent has as its main 

the justification and 

sure. The assessment 

out in relation to the 

individuals depends 

tors, some related to 

ir use of the environing their biological 

possible to evaluate 

ch of the exposed 

enerally possible to 

d population smaller 

dividuals who are 

i respect of those 

nine their exposure, 

alent to a specified 

n population group 

ed on the basis of a 

The spread of the 

an indication of the 

pie, and thus of the 

i statistical basis for 

ip has been suitably 

ossible to identify 

ith characteristics 

>ed at a higher level 

d population from a 

ure of these groups, 

can then be used as a 

measure of the upper limit of the individual 

doses resulting from the proposed practice. 

When several practices may contribute significantly to the exposure of the same exposed 

population, either simultaneously or successively, the definition of critical groups must 

take account of these separate contributions. 

(217) When the procedure is extended in 

time or the exposure results from environmental contamination, the individual and 

collective annual dose equivalents may rise to 

a maximum over a period of years even if the 

procedure continues at a constant level. Their 

maximum corresponds either to the achievement of an equilibrium condition or to the 

level resulting from the period of application 

of the practice. It is this maximum of the 

. average dose equivalent in the critical groups 

that should be compared with the corresponding dose-equivalent limit. 

(218) It is also useful in some cases to assess 

the dose-equivalent commitment or the 

collective dose-equivalent commitment. 

These are obtained by integrating over all time 

the average dose-equivalent rate throughout 

the exposed population and the collective 

dose-equivalent rate in that population, 

where each of these rates is that resulting from 

the application of a specified practice for a 

specified time, often a year. On the assumption that all relevant conditions remain 

constant, the annual mean dose equivalent 

and the annual collective dose equivalent will 

then reach equilibrium values equal to the 

dose-equivalent commitment and the 

collective dose-equivalent commitment per 

year of practice. The factors that have to 

remain constant include the rate of application of the practice, the environmental conditions, the size of the exposed population 

and the way people use that environment. 

In some instances, the practice cannot be 

assumed to continue for a sufficient time to 

allow for the annual collective dose equivalent 

to reach equilibrium. In this case, it is 

sufficient to integrate the collective doseequivalent rate over the period of the practice, 

as this integral is equal to the maximum 

annual collective dose equivalent to be experienced in the future from the practice. 

(219) Because of its complexity, assessments of collective dose equivalent involve the 

use of simplifications and approximations, 

particularly when a large population is irradiated at low dose levels. Because of this, they 

may involve considerable uncertainties and 

these must be borne in mind when the assessments are being used to appraise the detriment 

associated with a practice. 

The restriction of exposure 

The release of radioactive materials into the 

environment. (220) The restriction of the 

exposure which is caused by the release of 

radioactive materials into the environment 

depends on: 

the control of releases of gaseous and liquid 

effluents to the environment; 

the control of disposals to the environment 

of solid wastes; 

appropriate arrangements for reducing the 

probability of accidents giving rise to the 

releases of radioactive materials into the 

environment and for limiting the magnitude of these releases, should they occur. 

(221) Except for trivial amounts of activity, 

all releases of radioactive substances to the 

environment (including the disposal of solid 

wastes) should be subject to authorizations 

issued by the competent national authority. 

These authorizations should be based on preoperational studies which should, if necessary, include the assessment of the doseequivalent commitment to different 

population groups and, in particular, to the 

critical group, and the collective dose 

equivalents and collective dose-equivalent 

commitments. These studies should be 

carried out at an early stage of a project when 

it is still possible to introduce modifications. 

(222) These assessments require the use of 

models of various degrees of complexity, 

representing the movement of radioactive 

materials through the environment from the 
P.47 

40 RECOMMENDATIONS OF THE ICRP 

source to man. These models have to take into 

account the nature arid: the" physical and 

chemical forms of the radioactive materials, 

together with their methods of release. The 

models then have to reflect the characteristics 

of the environment and of man that influence 

the consequent exposure of individuals and 

groups. To make such models detailed and 

realistic requires extremely complex studies 

involving a considerable effort, and it is 

reasonable in practice to adjust the magnitude 

of this effort to the importance of the 

particular problem.* 

(223) In practice, the first stage is to carry 

out a simplified preliminary study based on 

existing information and making use of 

reasonably cautious hypotheses to bridge 

over the gaps in the information that always 

exist at this stage. In almost all situations the 

preliminary study will show that the 

exposures that might be caused by the 

proposed releases are extremely low and that 

sufficient information already exists for 

making decisions. In some cases, however, 

the preliminary study will indicate the need 

for further work, usually of limited scale. 

(224) When it appears that the exposures 

will be significant, it will usually be necessary 

to assess them with greater accuracy and to 

carry out more detailed studies directed 

principally at reducing the uncertainties 

indicated by the preliminary study. 

(225) The relationship between the rate of 

release and exposure of the critical group 

allows the assessment of a derived limit of 

release in each case. 

(226) The authorized limits of release are 

fixed by the national authorities at values 

which are generally lower than those of the 

derived limits. In setting such limits the 

authorities should apply, with an appropriate 

degree of detail, the processes of optimization, and should take account of other current 

or proposed sources of exposure. 

(227) Because of the different factors 

considered in the process of optimization, the 

authorized limit for the total release to a 

sector of the environment to which several 

installations release radioactive materials 

may be different from the sum of the optimized limits appropriate for each installation 

separately. When several installations make 

releases into the same sector of the environment, for example into the same river basin, it 

is necessary to assess the derived limit of 

release for the whole ofthe relevant sector. 

Direct external exposure from sources used 

for industrial, medical or scientific purposes. 

(228) The restriction of exposure in these cases 

is usually achieved with the aid of technical 

standards relating to the sources. In some 

cases, however, the restriction of exposure 

may form part of the design of the individual 

project. Any necessary reduction of exposure 

is usually obtained by the use of shielding, but 

exceptionally it may be necessary to define an 

area of restricted access or use in the vicinity 

ofthe source. 

The use of products widely distributed to 

the public. (229) It is convenient to distinguish 

between two categories of such products: 

those which include electronic equipment 

that emits x rays adventitiously; 

those which contain radioactive materials. 

(230) These two categories of product 

present different problems in the restriction 

of exposure. The first category gives rise only 

to external irradiation and that only during 

operations. For the second category, it is also 

necessary to take account of the possibility of 

contamination resulting from normal use, 

abnormal events and disposal. 

(231) The restriction of exposure from both 

these categories of product should be based 

on a control system at the national level aimed 

at ensuring that the exposures caused by each 

product are justified and then limited in an 

appropriate way. The appraisal of the consequences of the use of these products is 

jgmeiiaiHy based c 

(DsU'eKXtive dose equ 

amsQime applicatio 

tD3> tatke account 

fflspiwaients. The c 

gjjwaii application 

flesliuires of the de 

dfasiioe 'of the rad 

Hnnronilkictiion of shi 

0£33Mt:is often t 

arjjarrriicular appiicr 

sna^U while the re 

wnysenafi. it-is the 

qsaaanttitative appra 

Jfinte ffiinal decision 

agmaiiiittati ve j udgm e: 

((S3) Although 

ffirann -each type ol 

garasdiiicts are ust 

aastdhflarky should e 

nesaiMng from al 

ttmgsEtdiner remain wii 

fteaocepta'bie. 

((2Sft)The-pr,actic 

ffiranmn iproducts wl 

annttflsairized, .-is achi 

ffiarihnical .standards 

teamsttiics of :the pro< 

wikffln tthe conditic 

snniffilliitmes, iby pre 

tfflmiireventuivi dispo 

Ftoectiaes raising 

wdnma'i badkgroun, 

pnaeaiices that ma 

exposure from the 

laafianknvinclude: 

•This lopk- is discussed in detail in a report being prepared by ICRP Committee 4. 

:aaseol certain 

ttaamuDf buildings. 

Kaititude flyi 

: consumption 

fimwihich theconc 

eflamnents is.unusi 

ffiriigin or has bee 

%/ttihe use of fert. 

(Q36J In applying 

it is app 
RECOMMENDATIONS OF THE ICRP 41 

e total release to a 

ent to which several 

adioactive materials 

the sum of the opti-

• for each installation 

al installations make 

ector of the environhe same river basin, it 

the derived limit of 

ae relevant sector. 

're from sources used 

r scientific purposes. 

\posure in these cases 

the aid of technical 

ie sources. In some 

triction of exposure 

sign of the individual 

eduction of exposure 

: use of shielding, but 

ecessary to define an 

or use in the vicinity 

videly distributed to 

'enient to distinguish 

f such products: 

lectronic equipment 

titiously; 

dioactive materials. 

egories of product 

ns in the restriction 

egory gives rise only 

nd that only during 

id category, it is also 

: of the possibility of 

from normal use, 

osal. 

exposure from both 

ict should be based 

national level aimed 

;ures caused by each 

I then limited in an 

praisal of the consethese products is 

generally based on the magnitude of the 

collective dose equivalent that they cause, but 

in some applications it may also be necessary 

to take account of the individual dose 

equivalents. The exposure resulting from a 

given application can often be reduced by 

features of the design (for example, by the 

choice of the radionuclide used or by the 

introduction of shielding against x rays). 

(232) It is often the case that the benefits of 

a particular application, though real, are very 

small, while the resulting exposures are also 

very small. It is then very difficult to make a 

quantitative appraisal of the situation, and 

the final decision will often be based on 

qualitative judgment. 

(233) Although the exposures resulting 

from each type of these widely distributed 

products are usually low, the national 

authority should ensure that the exposures 

resulting from all the applications taken 

together remain within limits that it judges to 

be acceptable. 

(234) The practical restriction of exposures, 

from products whose use is justified and 

authorized, is achieved by compliance with 

technical standards dealing with the characteristics of the products and, in some cases, 

with the conditions of their use and, 

sometimes, by providing arrangements for 

their eventual disposal. 

Practices raising the level of exposure to 

natural background. (235) Examples of the 

practices that may increase the level of 

exposure from the natural background of 

radiation include: 

the use of certain materials in the construction of buildings and roads; 

high-altitude flying; 

the consumption of water and foodstuffs 

in which the concentration of natural radioelements is unusually high because of their 

origin or has been enhanced, for example 

by the use of fertilizers. 

(236) I n applying the system of limitation of 

exposure, it is appropriate to take account 

only of the change in exposure caused by (the 

assessed practice and not of the pre-existtiimg 

exposure level. The justification for most of 

the underlying practices (such as tdhse comsitroction of buildings) is self-evident, ami the 

emphasis in the restriction of exposure is 

therefore on optimization. The pmocess of 

optimization usually leads to tthe estabfchment of authorized limits for each significant 

situation. 

The use of radiation sources in mucking. 

(237) It is important to distinguish between 

two kinds of applications of radiation sources 

in teaching: 

the general teaching of sciencesubjeclis; 

specialized teaching of subjects concerned 

with radiations and their uses. 

In the first type of application the exposure 

resulting from demonstrations or experiments 

is likely to involve a very large mutmber of 

people and might thus contribute significantly to the general exposure. For this treason 

the Commission recommends that the annual 

dose equivalents received by indivMmal pupils 

during their courses should not exceed onetenth of the limits recommended for individual 

members of the public. The second ttype of 

application involves a much smaller number 

of people and is analogous to occupational 

exposure. Only exceptionally will the use of 

radiation sources in this kind of teaching 

require the conditions of work to be dassified 

as Working Condition A (see paragraph 161). 

Working Condition A should be pantnitted 

only where students are aged 18 years or over. 

The general procedures for restricting 

exposure should be broadly similar to those 

for occupational exposure although, in the 

absence of Working Condition A, they can be 

substantially simplified. More detailed 

recommendations are given in ICRP Publication 13. 

Monitoring of exposure 

Monitoring in normal conditions. (238) 

Releases of radioactive materials into the 
P.49 

42 RECOMMENDATIONS OF THE ICRP 

environment should be subject to appropriate 

monitoring to demonstrate compliance with 

the authorized release limits, unless other 

forms of assessment show this monitoring to 

be unnecessary. For major installations, the 

monitoring of releases may also contribute to 

the detection of abnormal situations. In most 

other cases, the monitoring of sources should 

be aimed at ensuring compliance with 

technical standards and the arrangements 

required by the national authorities. Special 

requirements may deal, for example, with the 

effectiveness of shields around sources, the 

characteristics of consumer products and the 

monitoring of control of their distribution, or 

the setting of activity limits for building 

materials. 

(239) In a few cases, essentially limited to 

situations where the exposure results from the 

release of radioactive materials into the 

environment, it may be necessary to supplement the monitoring of sources by monitoring 

of the relevant sector of the environment. 

Such monitoring may also be useful in verifying the validity of the models used in predicting exposure. The introduction of environmental monitoring is only necessary in the few 

cases where preoperational studies have 

shown that the installation might be the cause 

of a significant exposure of members of the 

public. Situations may also arise where 

several installations may release radioactive 

materials into the same sector of the environment and, even if each is individually insignificant, they may together make it necessary to 

introduce a program of environmental 

monitoring, usually of a limited nature. 

(240) Individual monitoring will not 

normally form a part of the monitoring of 

general exposure of the public, except in 

relation to some aspects of the use of 

radiation sources in teaching. In the specialized teaching associated with the characteristics or use of radiation sources, individual 

monitoring may be justified by the likely 

levels of exposure or by the fact that it forms a 

valuable introduction to good practice in 

subsequent work. 

Monitoring in abnormal circumstances. 

(241) In abnormal circumstances following, 

for example, an accident in an installation or 

during transport, it may be necessary to carry 

out monitoring if radioactive materials may 

have been released into the environment in 

quantities capable of causing a significant 

exposure of members of the public. This 

monitoring has the principal objective of 

obtaining information necessary to assess the 

situation and to decide on the need for intervention. It should also provide data for the 

evaluation of the exposure of members of the 

public, taking account of any countermeasures that have been applied. Furthermore, scientific information should also be 

collected with the aim of improving the 

prediction of consequences in such situations. 

The program of monitoring should be 

designed, at least in general terms, when an 

installation first becomes operational or a 

series of transport operations is first 

considered. 

Intervention 

(242) The form of intervention suitable for 

limiting an abnormal exposure to members of 

the public will depend on the circumstances. 

All the countenneasures that can be applied to 

reduce the exposure of members of the public 

after an accidental release of radioactive 

materials carry some detriment to the people 

concerned, whether it is a risk to health or 

some social disruption. The decision to 

introduce countermeasures should be based 

on a balance of the detriment which it carries 

and the reduction in the exposure which it can 

achieve. The magnitude of the detriment of 

countermeasures will vary with their nature 

and with the circumstances in which they are 

applied, for example, with the size of the 

population involved. Their effectiveness, on 

the other hand, will depend on the speed with 

which they can be introduced. For these 

reasons it is not possible to fix generally 

applicable intervention levels above which 

intervention will always be required. However, it might be 

which interventi 

considered to be. 

depend on the j 

each case and cai 

guidance. The de 

measures should': 

information avai 

tionieveisareexp 

dose equivalents 

helpful in practic 

ventKon levels api 

measurements fc 

monitoring progr: 

(243)To be,eff. 

pre-planned. An 

therefore be prep: 

menrsbers of the i 

sigtiM'dcant accide 

gency plan sfoould 

tihe special mon 

Sffituatiou (see pa 

tiae countcrmea 
.'«- fsss*. V * 

RECOMMENDATIONS OF THE ICRP 43 

mal circumstances. 

mstances following, 

in an installation or 

)e necessary to carry 

ctive materials may 

the environment in 

using a significant 

)f the public. This 

ncipal objective of 

cessary to assess the 

n the need for interirovide data for the 

e of members of the 

of any countera applied. Furthertion should also be 

of improving the 

cs in such situations, 

itoring should be 

:ral terms, when an 

:s operational or a 

perations is first 

ever, it might be possible to set levels below 

which intervention would not generally be 

considered to be justified. Intervention levels 

depend on the particular circumstances of 

each case and can therefore give only general 

guidance. The decision to introduce countermeasures should be taken in the light of all the 

information available at the time. Intervention levels are expressed in terms of individual 

dose equivalents or intakes. It will often be 

helpful in practice to provide derived intervention levels applicable to the results of the 

measurements forming part of the special 

monitoring program. 

(243) To be effective, intervention must be 

pre-planned. An emergency plan should 

therefore be prepared in any situation where 

members of the public may be subject to a 

significant accidental exposure. The emergency plan should include: 

the special monitoring needed to assess the 

situation (see paragraph 241); 

the countermeasures needed to reduce the 

exposure of members of the public together 

with the means necessary to put them into 

effect; 

the intervention levels and derived iMervention levels giving guidance on the different countermeasures. 

The emergency plan should be based ion a 

study of the radiological consequences ©f the 

releases following a reference accident. These 

consequences should be assessed rasing a 

method analogous to that described in 

paragraphs 222-234 for releases dnnring 

normal operations. The plan should be sefficiently flexible to allow its adaptation 5© the 

real situation, since this will differ firaam -that 

forecast. In particular, the inverventiomfisveis 

and the derived intervention levels shomM not 

be applied automatically; they should be 

treated as reference levels intended for 

guidance in making decisions and sfoonuDd be 

reassessed in the light of all the available 

information at the time of intervention. 

vention suitable for 

osure to members of 

I the circumstances, 

hat can be applied to 

•mbers of the public 

ase of radioactive 

iment to the people 

a risk to health or 

The decision to 

es should be based 

lent which it carries 

tposure which it can 

of the detriment of 

y with their nature 

es in which they are 

ith the size of the 

•ir effectiveness, on 

id on the speed with 

oduced. For these 

le to fix-generally 

evels above which 

be required. How-
RECOMMENDATIONS OF THE ICRP 45 

APPENDIX 

Rules governing the selection and work 

of the Commission 

The following are the Commission's rules, 

as approved by the International Congress of 

Radiology. 

1. (a) The International Commission on 

Radiological Protection (ICRP) shall be composed of a Chairman and not more than twelve 

other members. The selection of the members 

shall be made by the ICRP from nominations 

submitted to it by the National Delegations to 

the International Congress of Radiology and 

by the ICRP itself. The selections shall be 

subject to approval by the International 

Executive Committee (IEC) of the Congress. 

Members of the ICRP shall be chosen on the 

basis of their recognized activity in the fields 

of medical radiology, radiation protection, 

physics, health physics, biology, genetics, 

biochemistry and biophysics, with regard to 

an appropriate balance of expertise rather 

than to nationality. 

(b) The membership of the ICRP shall be 

approved during each International Congress, 

for service until the end of the succeeding 

Congress, or until new members are appointed. Not less than three but not more than 

five members shall be changed at any one 

Congress. In the intervening period vacancies 

may be filled by the ICRP. 

(c) In the event of a member of the ICRP 

being unable to attend the ICRP meetings, a 

substitute may be selected by the ICRP as a 

temporary replacement. Such a substitute 

shall not have voting privileges unless specifically authorized by the ICRP. 

(d) The ICRP shall be permitted to invite 

individuals to attend its meetings to give 

special technical advice. Such persons shall 

not have voting privileges, but their opinions 

may be recorded in the minutes. 

2. The Chairman shall be elected by the 

ICRP from among its members to serve until 

the end of the succeeding Congress, or until 

his successor is elected. The choice shall not be 

limited to the country in which it is proposed 

to hold the succeeding Congress. The Chairman shall be responsible for reporting the 

proceedings and recommendations of the 

ICRP at the next Congress. 

3. The ICRP shall elect from among its 

members a Vice-Chairman who will serve in 

the capacity of Chairman in the event that the 

Chairman is unable to perform his duties. 

4. Minutes of meetings and records of the 

ICRP shall be made by a Scientific Secretary 

selected by the Chairman of the ICRP, 

subject to the approval of its members. The 

Scientific Secretary need not be a member of 

the ICRP. The records of the ICRP shall be 

passed on to the succeeding Scientific Secretary. 

5. The Chairman, in consultation with the 

Vice-Chairman and the Scientific Secretary, 

shall prepare a program to be submitted to the 

Commission for discussion at its meetings. 

Proposals to be considered shall be submitted 

to the Chairman for circulation to all 

members of the ICRP and other specially 

qualified individuals at least 2 months before 

any meeting of the ICRP. 

6. Decisions of the ICRP shall be made by a 

majority vote of the members. A minority 

opinion may be appended to the minutes of a 

meeting if so desired by any member upon his 

submission of the same in writing to the 

Scientific Secretary. 

7. The ICRP may establish such committees 

as it deems necessary to perform its functions. 
P.52 

•46 

'MettLmmtrship 

The Commission's rules require that its 

members be elected every 4 years. The 

C. G. STEWART, Chairman 

B. LlNDElX, Vice-Chairman 

D. J. BENINSON 

HI JAMMET 

JL LlNlECKI 

A. X MCLEAN 

Y. f. MOSKALEV 

H. B. NEWCOMBE 

djamrnttee I on Radiation Effects 

A. C. UPTON, Chairman 

SL ABRAHAMSON 

G. W. BARENDSEN 

S. M. BROWN 

A. M. BRUES 

O. Hue 

(Dnamattee 2 on Internal Exposure 

k VENNART, Chairman 

W. J. BAIR 

G-. Cl BUTLER 

Gt W. DOLPHIN 

l_. E_ FEINENDEGEN 

W. JACOBI 

Ghummittee 3 on External Exposure 

VL LlNDELL, Chairman 

A . K.ELLERER 

E. E. KOVALEV 

L.-E. LARSSON 

C MEINHOLD 

RECOMMENDATIONS OF THE ICRP 

membership of the Commission and of its 

committeesfor 1973-1977 was as follows: 

E. E. POCHIN 

S. TAKAHASHI 

A. C. UPTON 

J. VENNART 

B. WINDEYER 

K. Z. MORGAN, Member Emeritus 

L. S. TAYLOR, Member Emeritus 

F. D. SOWBY, Scientific Secretary 

B. MODAN 

R. H. MOLE 

G. MORLAT 

P. OFTEDAL 

A.G. SEARLE 

V. ZELENY 

J. LAFUMA 

C. MAYS 

P. E. MORROW 

P. V. RAMZAEV 

W. S. SNYDER 

R. C. THOMPSON 

R. OLIVER, died 1976 

P. PELLERIN 

R. A. ROWLEY 

K. A STEVENS 

S. TAKAHASHI 

Method of Woi 

Much of the 

Commission oi 

performed by ac 

which theComr: 

the services of i 

who are not met 

way the Commi 

the appropriate i 

so that work a 

published withir 

if the Commissi 

ensure the safe a 

techniques in t. 

information. Ri 

lished are shown 

Relationships w 

The Commiss 

ship with the Wc 

the Internation; 

Close working : 

tained with the 

Committee on t. 

tion, the Uni 

Programme, the 

the IntertnvtionE 

sion, the Nncle 

European Gconc 

mission is repr 

number of me 

bodies; all of the 

(Dmamttee 4 on Application of the Commission's Recommendations 

M. JAMMET, Chairman 

ID. J. BENINSON 

H..J-. DUNSTER 

K. K.OREN 

E. KUNZ 

I>. MECHALI 

A. A. MOISEEV 

H. MUTH 

C. POLVANI 

L. ROGERS 

D. J. STEVENS 

E. G. STRUXNESS 

K. SUNDARAM 
.J.m£1&Li 

RECOMMENDATIONS OF THE ICRP 47 

ission and of its 

as as follows: 

tent us 

ritus 

etary 

Method of Work 

Much of the work of the International 

Commission on Radiological Protection is 

performed by ad hoc task groups, by means of 

which the Commission has been able to call on 

the services of a large number of individuals 

who are not members of a committee. In this 

way the Commission is able to bring together 

the appropriate experts rapidly and effectively 

so that work can be completed and reports 

published within the short time that is essential 

if the Commission's recommendations are to 

ensure the safe and rapid development of new 

techniques in the light of the most recent 

information. Reports that have been published are shown at the end of the appendix. 

Relationships with other bodies 

The Commission has an official relationship with the World Health Organization and 

the International Atomic Energy Agency. 

Close working relationships are also maintained with the United Nations Scientific 

Committee on the Effects of Atomic Radiation, the United Nations Environment 

Programme, the International Labour Office, 

the International Electrotechnical Commission, the Nuclear Energy Agency and the 

European Economic Community. The Commission is represented by observers at a 

number of meetings organized by these 

bodies; all of the above bodies are invited to 

send representatives to the Commission's 

meetings with its committees. 

Financial support 

Meetings of the Commission with its 

committees are held approximately every 2 

years, and the Commission itself meets about 

once a year. In addition, committees and task 

groups meet on their own to discuss and 

prepare their reports. The Commission has 

been able to support the travel costs of some 

of the individuals attending these meetings, 

thanks to grants of money generously made to 

it by the World Health Organization, the 

International Atomic Energy Agency, the 

United Nations Environment Programme, 

the International Society of Radiology, the 

International Radiation Protection Association, the Nuclear Energy Agency, the European Economic Community, and national 

sources in Canada, Japan and the United 

Kingdom. Nevertheless, the contribution that 

the Commission can make to travel expenses 

is severely limited, and during recent years 

between one-half and two-thirds of the total 

travel costs have been borne by the institutions 

of the ICRP members. The Commission is 

grateful for the amount of time made available to its work by the institutions of its 

members, and for all the financial support, 

without which it would not be possible to 

carry out its work. 
RECOMMENDATIONS OF THE ICRP 49 

PUBLICATIONS OF THE COMMISSION 

1. X-ray and Radium Protection. Recommendations of the 2nd International Congress of Radiology, 1928. Circular 

No. 374 of the Bureau of Standards, U.S. Government Printing Office (January 23, 1929). Br. J. Radiol., 1. 359 

(1928). 

2. Recommendations of the International X-ray and Radium Protection Commission. Alterations to the 1928 

Recommendations of the 2nd International Congress of Radiology. 3rd International Congress of Radiology, 

1931. Br. J.Radiol.. 4,485(1931). 

3. I nternational Recommendations for X-ray and Radium Protection. Revised by the International X-ray and Radi um 

ProtectionCommissionandadoptedby the3rd InternationalCongressof Radiology, Paris, July 1931 Br. J. Radiol., 

5,82(1932). 

4. International Recommendations for X-ray and Radium Protection. Revised by the International X-ray and Radium 

ProtectionCommissionandadopted by the4th International Congressof Radiology, Zurich, July 1934. Radiology, 

23,6S2-5(\9.4).Br. J. Radiol., 7,695(1934). 

5. International Recommendations forX-rayandRadium Protection. Revisedby the InternationalX-ray and Radium 

Protection Commission and adopted by the 5th International Congress of Radiology, Chicago, September 1937. 

BritishInstituteofRadiology(1938). 

6. International Recommendations on Radiological Protection. Revised by the International Commission on 

Radiological Protectionat the6th InternationalCongressof Radiology, London, 1950. Radiology, 56,431 -9 (1951). 

Br. J. Radiol.. 24,46-53(1951). 

7. Recommendations of the International Commission on Radiological Protection (Revised December I, 1954). 

Br. J. Radiol., Suppl.6(1955). 

8. Report on Amendments during 1956 to the Recommendations of the International Commission on Radiologics^ 

Protection (ICRP). Radial. Res., 8, 539-542 (1958). Acta Radiol., 48, 493-495 (1957). Radiology, 70, 26I-2S2 

(1958)fb/75cArittea.d.Gebieted.Rontgenstrahlenu.d.Nuclearmedizin, 88,500-502(1958). 

9. Recommendations of the International Commission on Radiological Protection (Adopted September 9, 1958). 

ICRPPublication /,PergamonPress,London(1959). 

10. Report on Decisions at the 1959 Meeting of the International Commission on Radiological Protection (ICRP). 

Radiology, 74,116-119(1960). Am. J. Roentg., 83,372-375 (1960). Strahtentherapie, 112,3(1960). Acta Radiol., 

53,2{1960).Br.J.Radiol., 33,189-192(1960). 

11. Recommendations of the International Commission on Radiological Protection (as amended 1959 and revised 

1962). ICRPPublication6, Pergamon Press, Oxford(l 964). 

12. Recommendations of the International Commission on Radiological Protection Report of Committee II on 

Permissible Dose for Internal Radiation (1959). ICRPPublication2, Pergamon Press, Oxford (1960). Health Phys., 

3,(1960). 

13. Recommendations of the International Commission on Radiological Protection Report of Committee III on 

Protection against X-rays up to Energies of 3 MeV and Beta- and Gamma-rays from Sealed Sources (1960). ICRP 

Publications, Pergamon Press, Oxford( 1960). 

14. Recommendations of the International Commission on Radiological Protection Report of Committee IV 

(1953-1959) on Protection against Electromagnetic Radiation above 3 MeV and Electrons, Neutrons and Protons 

(Adopted 1962, with revisions adopted 1963). ICRP Publication^ Pergamon Press, Oxford (1964). 

15. Recommendations of the International Commission on Radiological Protection Report of Committee V on the 

Handling and Disposal of Radioactive Materials in Hospitals and Medical Research Establishments. ICRP 

Publications, PergamonPress,Oxford(l965). 

16. Principles of Environmental Monitoring related to the Handling of Radioactive Materials. A report prepared 

by a Task Group of ICRP Committee 4, ICRPPublication 7, Pergamon Press, Oxford (1966).* 

17. The Evaluation of Risks from Radiation. A report prepared by a'Task Group of ICRP Committee I, ICRP 

Publications, Pergamon Press, Oxford (1966). Heallh Phys., 12,239-302 (1966). 

18. Recommendations of the International Commission on Radiological Protection. (Adopted September 17, 

1965). ICRP Publication 9, Pergamon Press, Oxford (1966). 

19. Report on amendments to ICRP Publication 9. Health Phys., 17, 389-390 (1969). Acta Radiol.. 8, 258 (1969). 

20. Report on the 1971 meeting of ICRP. Health Phys.. 21, 615-616 (1971). Phys. Med. Biol., 16, 693-695 (1971). 

21. Report on the 1972 meeting of ICRP. Health Phys., 24.360 (1973). Am. J. Roentg., 117,211 (1973). 

22. Report of Committee 4 on evaluation of radiation doses to body tissues from internal contamination due to 

occupational exposure. ICRP Publication 10, Pergamon Press, Oxford (1968).* 

23. The assessment of internal contamination resulting from recurrent or prolonged uptakes. A report of ICRP 

Committee 4. ICRP Publication 10A, Pergamon Press, Oxford (1971).* 

24. A review of the radiosensitivity of the tissues in bone. A report prepared by a Task Group for ICRP 

Committees I and 2. ICRP Publication II, Pergamon Press, Oxford (1968). 

• Recommendations of the ICR P applicable at the time of publication of this report. 
P.55 

50 RECOMMENDATIONS OF THE ICRP 

25. General principles of monitoring for radiation protection of workers. A report prepared by a Task Group of 

ICRP Committee4. ICRPPublication 12, Pergamon Press, Oxford (1969).* 

26. Radiation protection in schools for pupils up to the age of 18 years. A report by Committee 3 of ICRP. ICRP 

Publication 13, Pergamon Press. Oxford (1970).* 

27. Radiosensitivity and spatial distribution of dose. Reports prepared by two Task Groups of ICRP Committee 1. 

ICRP Publication 14, Pergamon Press, Oxford (1969). 

28. Protection against ionizing radiation from external sources. A report of ICRP Committee 3. ICRP Publication 

15. Pergamon Press, Oxford (1970).* 

29. Protection of the patient in x-ray diagnosis. A report prepared by a Task Group of ICRP Committee 3. ICRP 

Publication 16, Pergamon Press, Oxford (1970). 

30. Patient exposures in diagnostic radiology: Protection problems of current concern. A statement issued by the 

International Commission on Radiological Protection (ICRP). July 1973. Br. J. Radiol., 46, 1086-1088 (1973). 

31. Protection of the patient in radionuclide investigations. A report prepared for ICRP and adopted by the 

Commission in September 1969. ICRPPublication 17, Pergamon Press, Oxford (1971). 

32. The RBE for high-LET radiations with respect to mutagenesis. A report prepared by a Task Group of ICRP 

Committee 1. ICRPPublication 18, Pergamon Press, Oxford (1972). 

33. The metabolism of compounds of plutonium and other actinides. A report prepared by a Task Group of ICRP 

Committee 2. ICRP Publication 19, Pergamon Press, Oxford (1972). 

34. Alkaline earth metabolism in adult man. A report prepared by a Task Group of ICRP Committee 2. ICRP 

Publication 20, Pergamon Press, Oxford (1973). 

35. Data for protection against ionizing radiation from external sources: supplement to ICRP Publication 15. 

A report of ICRP Committee 3, ICRPPublication 21, Pergamon Press, Oxford (1973).* 

36. Implications of Commission recommendations that doses be kept as low as readily achievable. A report of 

ICRP Committee 4, ICRP Publication 22, Pergamon Press, Oxford (1973).* 

37. Report of the Task Group on Reference Man. A report prepared by a Task Group of Committee 2 of ICRP. 

ICRP Publication 23, Pergamon Press, Oxford (1975). 

38. Radiation protection in uranium and other mines. A report of ICRP Committee 4. ICRP Publication 24, 

Pergamon Press, Oxford (1977). 

39. The handling, storage, use and disposal of unsealed radionuclides in hospitals and medical research establishments. A report of a Task Group of ICRP Committees 3 and 4. ICRP Publication 25, Pergamon Press, Oxford 

(1977).* 

40. Planned and unplanned releases of radioactive materials into the environment. A report of ICRP Committee 4. 

(In preparation.) 

41. Principles concerning emergency and accidental exposures of workers. A report of ICRP Committee 4. (In 

preparation.) 

42. Radon, thoron and their daughter-products. A report of a Task Group of ICRP Committee 2. (In preparation.) 

43. Radionuclide Decay Schemes. A report .of ICRP Committee 2 (in preparation). 

44. Problems involved in developing an index of harm. A report of a Task Group of the International Commission 

on Radiological Protection. (In preparation.) 

45. Limits forintakeof radionuclides. A report of ICRP Committee 2. (In preparation.) 

46. Exposure of man to ionizing radiation arising from medical procedures. An enquiry into methods of evaluation. 

A report of the International Commissions on Radiological Protection and on Radiological Units and 

Measurements. Phys. Med. Biol., 2,107-151 (1957). 

47. Exposure of man to ionizing radiation arising from medical procedures with special reference to radiation 

induced diseases: An enquiry into methods of evaluation. A report of the International Commissions on 

Radiological Protection and on Radiological Units and Measurements. Phys. Med. Biol., 6, 199-258 (1961). 

48. Repon of the RBE committee to the International Commissions on Radiological Protection and on Radiological 

Units and Measurements. Health Phys., 9, 357-384 (1963). 

49. A review of the physiology of the gastrointestinal tract in relation to radiation doses from radioactive materials. 

A report prepared by a consultant to ICRP Committee 2. Health Phys., 12. 131-161 (1966). 

50. Dosimetry of the gastrointestinal tract. A report prepared by consultants to ICRP Committee 2. Heallh Phys., 

12,163-172(1966). 

51. Deposition and retention models for internal dosimetry of the human respiratory tract. A report prepared by a 

Task Group of ICRP Committee 2. Health Phys., 12, 173-207 (1966). Errata and revisions to report, Health 

Phys., 13,1251(1967). 

52. Radiobiological aspects of the supersonic transport. A report by a Task Group of ICRP Committee 1. Health 

Phys.. 12,209-226(1966). 

53. Calculation of radiation dose from protons and neutrons to 400 MeV. A report prepared by a Task Group of 

ICRP Committee 3. Health Phys., 12,227-237 (1966). 

54. Radiation dose from neutrons and protons in the energy range from 400 MeV to 2 GeV. A report prepared by a 

Task Group of ICRP Committees. Health Phys., 17,449-457 (1969). 

'Recommendations of the ICRP applicable at the time of publication of this report. 

Accidental exposure 

and quality factor 

and remedial actic 

management of 

of public 243 

Adventitious radiatii 

from electronic eq 

Annual limits of into 

use of weighting I"; 

calculation of 10 

Bone 

radiosensitive cells 

risk factor for 4? 

weighting factor f( 

Bone marrow (red) 

and leukaemia 4-

and haematopoieti 

risk factor for 44 

weighting factor fc 

Breast 

influence of age an 

risk factor for 57 

weighting factor Ic 

Carcinogenesis 

chief somatic eff ec 

risk factors for 4-

Cataract 

as non-stochastic e 

Children 

and radiation dam; 

Collective dose equiv. 

and detriment 24 

and population exp 

definition 22 

from a practice 2.' 

Committed dose equi 

and annual limits o 

definition 26 

Competent authority 

medical authority 

statutory competen 

technically compete 

Conditions of work 

Working condition 

Working condition 

Working condition 

Controllable sources 

and dose limitation 

Controlled area 

access to 168 

and working condit 
RECOMMENDATION

S OF THE ICRP 

51 

by a Task Group of 

tee 3 of ICRP. ICRP 

" ICRP Committee I. 

3. ICRP Publication 

• Committee 3. ICRP 

;tement issued by the 

•5, 1086-1088(1973). 

and adopted by the 

"ask Group of ICRP 

Task Group of ICRP 

Committee 2. ICRP 

ZRP Publication 15. 

lievable. A report of 

jmmittee 2 of ICRP. 

"RP Publication 24, al research establishjamon Press, Oxford • ICRP Committee 4. tP Committee 4. (In 

e2. (In preparation.) 

lational Commission 

ethods of evaluation, 

iiological Units and 

.-ference to radiation 

ial Commissions on 

6, 199-258(1961). 

i and on Radiological 

adioactive materials. 

ttee2. Health Phys., 

report prepared by a 

ms to report. Health 

Committee I. Health 

by a Task Group of 

report prepared by a 

INDEX 

Individual items in this publication are indexed by paragraph number. 

Accidental exposures 

and quality factor 21 

and remedial actions 133 

management of 188-194 

of public 243 

Adventitious radiation 

from electronic equipment 

Annual limits of intake 

use of weighting factors with 

calculation of 109 

229 

107 

•Bone 

radiosensitive cells of 47 ' risk factor for 48 

weighting factor for 105 

Bone marrow (red) 

and leukaemia 44 

and haematopoietic cells 45,46 

risk factor for 44 

weighting factor for 105 

Breast 

influence of age and sex on risk factor 

risk factor for 57 

weighting factor for 105 

38 

Carcinogenesis 

chief somatic effect 7 

risk factors for 44-60 

Cataract as non-stochasti

c effect 8 

Children 

and radiation damage 65 

Collective dose equivalent 

and detriment 24 

and population exposure 131, 132,218,219 

definition 22 

from a practice 23 

Committed dose equivalent 

and annual limits of intake 109 

definition 26 

Competent authority 

medical authority 93 

statutory competent authorities 139 

technically competent person 160 

Conditions of work 

Working condition A 161-166 

Working condition B 161-166 

Working condition B and pregnancy 116 

Controllable sources 

and dose limitation 81 

Controlled area 

access to 168 

and working conditions 163 

Countermeasures 

see Remedial actions 

Critical groups 

and dose limitation. 84,216 

and release limits 225 

dose-equivalent limits for 119-125, 217 

optimization of exposure 121-123 

variable characteristics of 85,214 

Critical organ 

in relation to risk 36 

Derived limit 

use of 82,147,175,176 

Detriment 

and collective dose 24 

and operational optimization 154 

definition 16 

Dose equivalent 

and modifying factors 18 

definition 17, 18 

limitation of applicability 21 

Dose-equivalent commitment 

and future exposures 13 

definition 25 

use of 218 

Dose-equivalent limit 

and system of dose limitation 11,12 

and stochastic risk 78 

and non-stochastic damage 78 

and medical exposure 83, 91-95 

and natural background 83, 87-90 

for workers 96-116 

for members of the public 117-128 

to prevent non-stochastic effects 8 

Dose-response relationship 

assumptions about 27 

varieties of 28 

Embryo 

see Foetus 

Emergencies 

see Accidental exposures 

Environment 

release of radioactivity to 220-227 

Fertility 

impairment of 8,42 

Foetus 

and medical exposure 206 

and occupational exposure 

irradiation of 65 

115, 116 
P.57 

.52 

Gastrointestinal tract 

radioseBBtivity of 58 

weighting factor for 105 

Genetic do« limit 

recommended formerly 129 

Gonads 

and cancer 41 

and fertSty 42 

and hereditary effects 43 

risk factor for 43 

weighting factor 105 

Hereditary effects 

and fomcr genetic dose limit 129 

and reproductive life of workers 80 

definition 6 

in immediate offspring 80 

stochastic 7 

RECOMMENDATIONS OF THE ICRP 

Intervention 

and abnormal situations 

and optknization 157 

levels 133,152, 188 

Investigation level 

useof 151,177-181 

143, 188-194,242,243 

Justification of exposures 10

, 12,68,69 

Lens 

and cataract 8 

dose-cq«valent limit for 61 

opacification in 61 

radiosensitive cells in 62 

Levels 

intervention 133,152, 188 

investigation 151, 177-181 

reference 149.161 

Tcaxdmg 150 

Limits 

authorad 148, 175, 176, 226,227, 236 

basic 344 

derived 147,175,176 

secondary 146 

Linearity 

see also Dose-response relationship 

assumption about 27 

at low doses 28 

limitations 30 

Lung 

and particulates 33, 50 

cancer ia: 49 

-lymphoid tissue in 52-54 

Tisk faaor for 51 

- weighting factor for 105 

Medical exposure 

.and dose-equivalent limits 

.and noo-stochastic effects 

;and pregnancy 206 

and raSodiagnosis 197 

and raifiotherapy 198 

and research 203,204 

and taking 208 

83,91-93 

93,95 

medico-legal and insurance 202 

optimization of 205 

systematic examinations 200,201 

Medical surveillance 

in abnormal situations 188 

of workers 184-186 

Members of the public 

and acceptability of risk 118 

and critical groups 119-124 

and dose limitation 84 

and non-stochastic effects 126 

and teaching 237 

dose-equivalent limit for 119-126 

risks to 117 

weighting factors for 125 

Modifying factors 

and dose equivalent 18 -

Monitoring 

and occupational exposure 173-183 

and working conditions 162 

environmental 238 

in abnormal circumstances 241 

optimization of 156 

Natural radiation 

and dose-equivalent limits 83, 87-90 

and man-made enhancement 88, 89, 235 

Non-specific effects 

and low doses 67 

Non-stochastic effects 

and dose limitation 95 

definition 7 

dose-equivalent limits for 103,126 

somatic 8 

Non-uniform irradiation 

and dose limitation 104,110 

Occupational exposure 

abnormal situations 188 

conditions of work 161 

distribution of 100-102 

dose-equivalent limits for 96-116 

medical surveillance 184 

monitoring of exposure 173 

risks in safe industries 96-102 

total detriment from 97-98 

Optimization 

and cost-benefit analysis 70-76 

and dose-equivalent limits 76 

and enhanced natural radiation 236 

and safety factors 159 

and technical standards 158,228 

operational 153-159 

Particulates 

and irradiation of lung 33, 50 

Patient 

protection of 197-209 

Planned special exposures 

dose equivalents permitted 113 

management of 114,192 

Population 

and dose limitation 130 

and former genetic dose limit 129 

exposure of 129-1 

Pregnancy 

and occupational e.-

and radiological ex; 

Protective equipment 

and occupational e> 

and planned special 

Pulmonary lymphoid 

distribution ol 52-

Quality factor 

and dose equivalent 

and RBE 21 

approximate values 

definition 19 

limitation ol'applic: 

Rate of dose accumul: 

and age-related for: 

and dose-equivalerr 

Recording level 

useof 150 

Reference level 

and condition of wi 

useof 149 

Reference man 

and secondary limit 

characteristics of 

Regulations 

relation to !""RP re<. 

Remedial actio.is 

and intervenion 1 

and uncontrolled sc 

in accidents 133-1 

Risk factors 

and radiation protei 

definition ?A 

relation to a •? and s 

relation to hurt and 

Sievert 

unit ofdoseequival 

Significant volumes ai 

and mean dose 32 

and skin 34, 182, i 
RECOMMENDATION

S OF THE ICRP 

53 

201 

-126 

3-183 

126 

exposure of 129-132,218, 219,229 

Pregnancy 

and occupational exposure 116 

and radiological examinations 206 

Protective equipment 

and occupational exposure 167 

and planned special exposures 171 

Pulmonary lymphoid tissue 

distribution of 52-54 

Quality factor 

and dose equivalent 18 

and RBE 21 

approximate values of 20 

definition 19 

limitation of applicability 21 

Rate of dose accumulation 

and age-related formula 35 

and dose-equivalent limits 35 

Recording level 

use of 150 

Reference level 

. and condition of work 161 

"useof 149 

Reference man 

and secondary limits 146 

characteristics of 127 

Regulations 

relation to ICRP recommendations 

Remedial actions 

and intervention 143, 242 

and uncontrolled sources 81 

in accidents 133-135,192 

Risk factors 

and radiation protection 29 

definition 24 

relation to age and sex 38 

relation to hurt and suffering 39 

Sievert 

unit of dose equivalent 18 

Significant volumes and areas 

and mean dose 32 

and skin 34,182,183 

Skin 

assumed depth 64 

dose-equivalent limit 63 

monitoring of 182,183 

non-malignant damage to 8, 63 

Somatic effects 

definition 6 

Stochastic effects 

and dose-equivalent limit 104-112 

definition 7 

hereditary 7 

limitation of 10 

somatic 7 

Supervised area 

access to 168 

and working conditions 163 

Teaching 

dose-equivalent limits for 237 

Threshold dose 

and dose-equivalent limits 10 

and non-stochastic effects 7 

Thyroid 

cells at risk 55 

risk factor for 56 

weighting factor for 105 

Total risk 

cancer 58,59 

somatic plus hereditary 60 

Training 

and medical exposure 208, 209 

and occupational exposure 172 

Vacation 

and occupational exposure 187 

Weighting factors 

for dose limitation 104, 105, 125 

Whole body exposure 

dose-equivalent limit for 104-112, 

Women of reproductive capacity 

and occupational exposure 115 

and planned special exposures 114 

Working hours 

and occupational exposure 187 

and teaching 237 

119 

236 

:28 
STATEMENT FROM 

THE 1978 STOCKHOLM MEETING OF THE INTERNATIONAL 

COMMISSION ON RADIOLOGICAL PROTECTION 

The International Commission on Radiological Protection (ICRP) held its annual 

meeting in Stockholm in May, 1978, 

together with its four expert committees. 

Sixty-five individuals from seventeen 

countries were present to review the 

Commission's current work and to decide on 

a programme of work for the next 4-year 

period. Representatives or observers were 

also present from the Commission of the 

European Communities, the International 

Atomic Energy Agency, the International 

Commission on Radiation Units and 

Measurements, the International 

Electrotechnical • Commission, the 

International Radiation Protection 

Association, the International Society of 

Radiology, the OECD Nuclear Energy 

Agency, the United Nations Environment 

Programme, the United Nations Scientific 

Committee on the Effects of Atomic 

Radiation and the World Health 

Organization. 

ICRP PUBLICATION 26 

The Commission also reviewed its 1977 

recommendations (ICRP Publication 26) 

and identified the following points that 

require clarification. 

Estimates of radiation risk 

The risk factors given by the Commission 

in ICRP Publication 26 (paragraphs 36-60) 

are based on advice received from its 

committee on radiation effects. They are 

consistent with data available in the 

scientific literature and with information 

included in the 1977 report of the 

UNSCEAR. 

In the light of its continuing review of the 

published information on the 

epidemiological and radiobiological 

evidence of radiation risks to man, the 

Commission has concluded that the 

information available up to May 1978 does 

not call for changes in the risk factors given 

in ICRP Publication 26. These risk factors 

are intended to be realistic estimates of the 

effects of irradiation at low annual dose 

equivalents (up to the Commission's 

recommended dose-equivalent limits). 

In dealing with the stochastic effects of 

ionizing radiation the Commission 

recommended (in paragraph 105 of ICRP 

Publication 26) weighting factors for 

application to the dose equivalent in various 

organs and tissues. The Commission wishes 

to point out that it did not intend the hands 

and forearms, the feet and ankles, the skin 

and the lens of the eye to be included in the 

"Remainder". These tissues should 

therefore be excluded from the computation 

of I jw-rHj. In order to prevent the 

occurrence of non-stochastic effects, the 

Commission recommends that the relevant 

dose-equivalent limits given in paragraph 

103 should apply to these tissues. 

In the assessment of detriment from 

exposure of population groups a small risk 

of fatal cancer resulting from exposure of 
P.60 

the skin may need to be taken into account, 

for example in the case of exposure of the 

whole skin from soft beta radiation. In this 

case a risk factor in the region of IO"4 Sv-1 

may be applied to the mean dose over the 

entire surface of the skin, which would 

correspond to a value of wT of about 0.01. 

The Commission's occupational dose 

limits are intended to apply to all workers, 

and are based on average values of risk 

factors for male and female adults. The 

variations of risk with exposure at different 

ages in the two sexes, referred to in 

paragraph 38 of ICRP Publication 26, are 

discussed in ICRP Publication 27, a report 

to the Commission on "Problems involved 

in developing an index of harm". This 

report also reviews the basis for the 

selection, in ICRP Publication 26 

(paragraph 60) of an average genetically 

significant fraction (0.4) of occupational 

exposure and the mean mortality risk factor 

(10~2 Sv-') for both sexes and all ages. 

Effective dose equivalent 

The Commission recommends that the 

sum 1T-WTHT (see paragraph 104 of ICRP 

Publication 26) be called the effective dose 

equivalent (denoted HE). 

Modifications to the text of ICRP 

Publication 26 

The Commission believes that the 

following textual revisions to certain 

paragraphs in ICRP Publication 26 will 

clarify their meaning. 

(38) The fourth and fifth sentences should 

read: 

For protection purposes therefore, 

sufficient accuracy is obtained by 

using a single effective dose-equivalent limit for all workers regardless 

of age or sex. This limit is based 

upon the average risk levels described 

below for the various organs or 

tissues. 

(79) The first sentence should read: 

The Commission's dose-equivalent 

limits for workers are intended to 

apply to the sum of the dose equivalent resulting from external exposure 

during 1 year and the committed 

dose equivalent from that year's 

intake of radionuclides. 

(79) Add the following sentence at the end 

of the paragraph: 

Similar principles apply to the doseequivalent limits for members of the 

public. 

(89) In the second sentence the following 

should be deleted: 

"are intended as guides for planning 

purposes, and thus" 

(93) In the first sentence the following 

should be deleted: 

"are intended for planning purposes 

and" 

(107) The end of the last sentence should 

read: 

. . . namely, the limit to the deep and 

shallow dose-equivalent indices //j t d 

and HltS (see paragraph 108) and 

ALI (see paragraph 109). 

(108) The last part ofthe first sentence should 

read: 

. . . it is possible to assess the maximum value of dose equivalent that 

would occur at a depth of 1 cm or 

more in a 30 cm diameter sphere (the 

deep dose-equivalent index, //|>d). 

(108) The following sentence should be 

added at the end of the paragraph: 

In addition, the shallow dose-equivalent index (the maximum dose 

equivalent in the shell from 0.07 mm 

to 10 mm depth in the 30 cm sphere) 

should be limited to 500 mSv to 

provide i 

practical 

the deep 

alent inc 

dose equi 

to less th; 

(110) Theparagr; 

When ex 

ures are 

Commiss 

limits will 

following 

W 

and 

H l.S 

H. sk.L 

where Hx 

equivalent 

shallow d< 

is the anr 

The first group 

of intake (ALI) 

together with th< 

includes the met 

metabolic data 

available at the * 

Stockholm, and i 

publication in a re; 

for intakes of rat 

Similar informatic 
&M 

/anous organs or 

tould read: 

:'s dose-equivalent 

rs are intended to 

of the dose equivaT external exposure 

nd the committed 

from that year's 

elides. 

entence at the end 

apply to the dose-

:'or members of the 

;nce the following 

;uides for planning 

s" 

ice the following 

planning purposes 

provide protection for the skin. In 

practical situations, these limits on 

the deep and shallow dose-equivalent indices will limit the annual 

dose equivalent in the lens of the eye 

to less than 300 mSv. 

(110) The paragraph should read: 

When external and internal exposures are received together, the 

Commission's recommended dose 

limits will not be exceeded if both the 

following conditions are met: 

^E.L j 4,L 

and 

H I.s 

H 

< 1 

sk.L 

where HXi is the annual deep doseequivalent index, HltS is the annual 

shallow dose-equivalent index, HEL 

is the annual limit of the effective 

dose equivalent (50 mSv), H^L is 

the annual limit of dose equivalent 

in the skin (500 mSv), I. is the annual 

intake of radionuclide j , AJL is the 

annual limit of intake for radionuclide j . 

(113) The second sentence should read: 

In such circumstances external 

exposures and intakes of radioactive 

material may be permitted provided 

that the sum of the dose equivalent 

from the external exposure and the 

committed dose equivalent from the 

intake of radionuclides does not 'exceed twice the relevant annual limit 

in any single event, and, in a lifetime, 

five times this limit. 

(187) In the first sentence, the term "doseequivalent limit" should be replaced 

by "system of dose limitation". 

(238) In the last sentence the term "monitoring of control" should read "nraomkoring or control". 

t sentence should SECONDARY LIMITS FOR INTERNAL EXPOSURE 

.nit to the deep and 

valent indices Hld 

ragraph 108) and 

•h 109). 

rst sentence should 

o assess the maxise equivalent that 

depth of 1 cm or 

ameter sphere (the 

.*nt index, Hld). 

The first group of values of annual limits 

of intake (ALI) for radiation workers, 

together with the text of a report that 

includes the methods of calculation and 

metabolic data for 22 elements, were 

available at the Commission's meeting in 

Stockholm, and are now in the course of 

publication in a report to be entitled "Limits 

for intakes of radionuclides by workers". 

Similar information on additional elements 

will be published as soon as it becomes 

available. 

Organ dose estimates for members of the 

public cannot be derived directly from the 

data given for workers because of 

differences in metabolism, organ size and 

duration of exposure. The Coeramission is 

therefore planning to issue specific guidance 

on the assessment of internal exposure of 

members of the public. 

tence should be 

he paragraph: 

tallow dose-equivmaximum dose 

lell from 0.07 mm 

the 30 cm sphere) 

I to 500 mSv to 
P.62 

CURRENT WORK OF ICRP 

Four reports are being completed, 

preparatory to publication in the Annals of 

the ICRP. The titles of the reports are: -

— Biological effects of inhaled radionuclides. 

-Limits for intakes of radionuclides by 

workers (to replace ICRP Publication 2). 

— Radionuclide releases into the 

environment: assessment of doses to 

man. 

— Monitoring for internal contamination 

due to occupational exposure (to replace 

ICRP Publications 10 and 10A). 

A full programme of work is planned for 

the Commission and its committees and task 

groups in the immediate future. Subjects 

receiving urgent review

 :—'"J

- *u-

following: 

— Non-stochastic effects! 

-Risks and RBEs of hi 

-Risks to the human embryo and 

foetus-with special reference to 

occupational exposure of women. 

— Doses to patients from 

radiopharmaceuticals. 

— Protection in all fields in which ionizing 

radiations are employed in medicine. 

-The practical application of the Commission's recommendations. 

— Application of the ICRP system of dose 

limitation to practices that modify man's 

exposure to natural background radiation. 

During its term of office the Commission 

plans to prepare revised versions of its 

Publications 7, 10, 12, 13, 15/21, 16, 17 and 

24. 

for carcinogenesis: 

— Somantic and heredilj 

ation at low doses. 25PU 

RA 

1231 

R2In31 

n o . 26 

c.22 

Intemat'l . Comm. on Rad. Prot . 

Recomm. of th e Intemat'l . Comm. 

on Rad. Prot . 

; said Scope 

Founded in 1928. t 

beeira providing gen 

by rapid developmc 

The reports and reo 

journal. Annals of h 

repeat as so o n a s i t it 

in this important fie! 

Single issues of the j 

who do not require 

copy of a particula 

bookseller, subscrip 

Contents of Volume 

No E ICRP Publica; 

Radiation Protectioi 

No. 2 ICRP Publica 

The Handling. Store 

Hospitals ami Medic 

No. 3 ICRP Publica 

Recommendations oj 

No. 4 ICRP Publica 

iems Invoked in 

Forthcoming Issues 

Forthcoming Issues 

Principles Concernir 

Limits for Intakes ol 

Planned and Unplar 

Biological EITects of 

Radon, Thoron and 
finals of the ICR 

man embryo and 

;ial reference to 

arc of women. 

patients from 

tls. 

Ids in which ionizing 

oyed in medicine, 

cation of the Comldations. 

:CRP system of dose 

es that modify man's 

1 background radiance the Commission 

sed versions of its 

3, 15/21, 16, 17 and 

ad. Prot. 

at'l . Comm, 

15PU 

Aims and Scope 

Founded in 1928, the International Commission on Radiological Protection has since 1950 

been providing general guidance on the more wide-spread use of radiation sources caused 

by rapid developments in the field of nuclear energy. 

The reports and recommendations ofthe ICRP are now available in the form of a new review 

journal, Annals ofthe ICRP. Subscribers to the journal will be assured of receiving each new 

report as soon as it appears, thus ensuring that they are kept abreast ofthe latest developments 

in this important field, andean build up a complete set of ICRP reports and recommendations. 

Single issues of the journal will be available separately for those individuals and organizations 

who do not require a complete set of all ICRP publications, but would like to have their own 

copy of a particular report covering their own field of interest. Please order through your 

bookseller, subscription agent or, in case of difficulty, direct from the publisher. 

Contents of Volume 1 

No 1 ICRP Publication No. 24 

-Radiation Protection in Uranium and other Mines 

No. 2 ICRP Publication No. 25 

The Handling, Storage, Use and Disposal of Unsealed Radionuclides in 

Hospitals and Medical Research Establishments 

No. 3 ICRP Publication No. 26 

Recommendations ofthe International Commission on Radiological Protection 

No. 4 ICRP Publication No. 27 

Problems Involved in Developing an Index of Harm 

Forthcoming Issues 

Forthcoming Issues of the Annals will include reports on the following topics: 

Principles Concerning Emergency and Accidental Exposures 

Limits for Intakes of Radionuclides by Workers 

Planned and Unplanned Releases of Radioactive Materials 

Biological Effects of Inhaled Radionuclides 

Radon, Thoron and Daughter Products