Radiation Protection Standards for Radioluminous Timepieces

N o . 23

Radiation Protection Standards for Radioluminous Timepieces

REC O M M EN D A T IO N S OF THE EUROPEAN NUCLEAR ENERGY AG EN CY

AND THEINTERNATIONAL A T O M IC ENERGY A G E N C Y

I N T E R N A T I O N A L A T O M I C E N E R G Y A G E N C Y

V I ENNA, 1967

This publication is no longer valid Please see http://www.ns-iaea.org/standards/

RADIATION PROTECTION STANDARDS

FOR RADIOLUMINOUS TIMEPIECES


The following States are Members of the International Atomic Energy Agency:

AFGHANISTAN GERMANY, FEDERAL NIGERIAALBANIA REPUBLIC OF NORWAYALGERIA GHANA PAKISTANARGENTINA GREECE PANAMAAUSTRALIA GUATEMALA PARAGUAYAUSTRIA HAITI PERUBELGIUM HOLY SEE PHILIPPINESBOLIVIA HONDURAS POLANDBRAZIL HUNGARY PORTUGALBULGARIA ICELAND ROMANIABURMA INDIA SAUDI ARABIABYELORUSSIAN SOVIET INDONESIA SENEGAL

SOCIALIST REPUBLIC IRAN SIERRA LEONECAMBODIA IRAQ SINGAPORECAMEROON . ISRAEL SOUTH AFRICACANADA ITALY SPAINCEYLON IVORY COAST SUDANCHILE JAMAICA SWEDENCHINA JAPAN SWITZERLANDCOLOMBIA JORDAN SYRIAN ARAB REPUBLICCONGO, DEMOCRATIC KENYA THAILAND

REPUBLIC OF KOREA, REPUBLIC OF TUNISIACOSTA RICA KUWAIT TURKEYCUBA LEBANON UKRAINIAN SOVIET SOCIALISTCYPRUS LIBERIA REPUBLICCZECHOSLOVAK SOCIALIST LIBYA UNION OF SOVIET SOCIALIST

REPUBLIC LUXEMBOURG REPUBLICSDENMARK MADAGASCAR UNITED ARAB. REPUBLICDOMINICAN REPUBLIC MALI UNITED KINGDOM OF GREATECUADOR MEXICO BRITAIN AND NORTHERN IREUEL SALVADOR MONACO UNITED STATES OF AMERICAETHIOPIA MOROCCO URUGUAYFINLAND NETHERLANDS VENEZUELAFRANCE NEW ZEALAND VIET-NAMGABON NICARAGUA YUGOSLAVIA

The Agency's Statute was approved on 26 October 1956 by the Conference on the Statute of the IAEA held at United Nations Headquarters, New York; it entered into force on 29 July 1957.. The Headquarters of the Agency are situated in Vienna. Its principal objective is "to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world".

© IAEA. 1967

Permission to reproduce or translate the information contained in this publication may be obtained by writing to the International Atomic Energy Agency, K&rntner Ring 11, A-1010 Vienna I, Austria.

Printed by the IAEA in Austria

September 1967


SAFETY SERIES No.23

RADIATION PROTECTION STANDARDS

FOR RADIOLUMINOUS TIMEPIECES

RECOMM ENDAT IONS DRAWN UP BY A JOINT GROUP OF EXPERTS OF THE

EUROPEAN NUCLEAR ENERGY AGENCY AND THE

INTERNATIONAL ATOMIC ENERGY AGENCY

INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA, 1967


RADIATION PROTECTION STANDARDS FOR RADIOLUMINOUS TIMEPIECES (Safety Series, No. 23)

ABSTRACT. The recommendations of a joint group of experts set up by the IAEA and the European Nuclear Energy Agency of the Organization for Economic Co-operation and Development (OECD). The draft recommendations were circulated to all Member States of both organizations, the International Labour Organisation (ILO), the World Health Organization (WHO) and the International Commission on Radiological Protection (ICRP) and were finally approved in 1966. The Council of the OECD recommended that the measures taken by its Member States to provide adequate protection against the hazards of ionizing radiations for users of radioluminous timepieces and for the whole population be based on ’Radiation Protection Standards for Radioluminous Timepieces'.

Contents: Members of the group o f experts ; Explanation of terms used; Scope; General requirements; Special requirements; Appendix — Control procedures for radioluminous timepieces; Annex I — Selection of radionuclides to be used in radioluminous timepieces; Annex II — Radiation protection considerations and determination of maximum permissible activities of radionuclides recommended for radioluminous timepieces.

Available in English, French, Russian and Spanish.

(37 p p ., 14. 8 x 21 cm, paper-bound)(1967) Price: US$1.00- 7/2 stg.

THIS MANUAL IS ALSO PUBLISHED IN FRENCH, RUSSIAN AND SPANISH

RADIATION PROTECTION STANDARDS FOR RADIOLUMINOUS TIMEPIECES

IAEA, VIENNA, 1967 S T I/P U B /167


FOREWORD

With a view to obtaining international agreement on recommendations to promote safety in compliance with internationally agreed radiation protection standards, and also to facilitating trade and commerce, the European Nuclear Energy Agency (ENEA) of the Organization for Economic Co-operation and Development (OECD) and the International Atomic Energy Agency (IAEA) set up a joint group of experts from Belgium, Czechoslovakia, France, Federal Republic of Germany, Japan, Switzerland, the United Kingdom and the United States of America to prepare a draft of radiation protection standards for radioluminous timepieces.

The group of experts met twice in Paris in February 1964 and May 1965 and prepared a draft of the recommendations which was circulated in the Autumn of 1965 to all Member States of both organizations, the International Labour Organisation (ILO), the World Health Organization (WHO) and the International Commission on Radiological Protection (ICRP). In the light of the comments received, these draft recommendations were finally agreed in May 1966, during a meeting of the ENEA Health and Safety Committee, with the help of the secretariats of both the ENEA and IAEA organizations.

The draft recommendations were approved by the OECD Council at its meeting held on 19 July 1966*. The Council decided that the governments of its Member States shall ensure that appropriate measures be taken to provide adequate protection against the hazards of ionizing radiations for users of radioluminous timepieces and for the whole population. The Council recommended that these measures be based upon "the Radiation Protection Standards for Radioluminous Timepieces" and that the control procedures described in the appendix to these Standards be used to ensure that the manufacture of radioluminous timepieces complies with the requirements laid down in these Standards.

* The application of the Council Decision by the Federal Republic of Germany requires ratification in accordance with its Constitutional Procedures.


The draft recommendations were also approved by the Board of Governors of the IAEA at its meeting held on 19 September 1966. The Board decided that the Standards set forth in this document shall constitute the Agency's Radiation Protection Standards for Radio- luminous Timepieces, recommended to all its Member States that their relevant national regulations should conform, as far as practicable, to these Standards, and authorized the Director General of IAEA in collaboration with the Director General of ENEA, after obtaining the necessary advice, to arrange for such changes of detail in the Standards as will be needed from time to time to keep them technically up to date, provided that he shall give 90 days' advance notice of such changes to Member States and that comments received thereon shall be taken into consideration by the technical advisers.


CONTENTS

1. EXPLANATION OF TERMS USED ................................................. 32. SCOPE ..................................................................................................... 43. GENERAL REQUIREMENTS ............................................................. 54. SPECIAL REQUIREMENTS ................................................................ 7

APPENDIX: Control procedures for radioluminoustim ep ieces..................................... ......................................... 11

ANNEX' I: Selection of radionuclides to be used inradioluminous timepieces ................................................ 14

ANNEX II: Radiation protection considerations and determination of maximum permissible activities of radionuclides recommended for radioluminous timepieces ............................................................................... 30

MEMBERS OF THE GROUP OF EXPERTS ..................................... 1


MEMBERS OF THE GROUP OF EXPERTS

The composition of the group of experts who took part in the drawing up of the Draft Standards was as follows:

M r. R . E . Cunningham,Division of M aterials Licensing,Atomic Energy Com m ission,Washington,United States of Am erica

D r. A . Lafontaine,Institut d'Hygifene et d'Epidemiologie,Bruxelles,Belgique

Professor W . Minder,Section de Radioprotection,Service Federal de l'Hygi&ne Publique,Berne,Switzerland

D r. J. Muller,Institute of Radiation Hygiene,Prague,Czechoslovakia

P rofessor Y . Nishiwaki,Department of Radiation Protection,Research Laboratory of Nuclear Reactor,Tokyo Institute of Technology,Tokyo,Japan

Professor P. Pellerin,Service Central de Protection contre les Rayonnements Ionisants, Ministfere des Affaires Sociales,Le Vesinet,France

1


D r. J. Schwibach,Bundesm inisterium fiir w issenschaftliche Forschung, Bad G odesberg,F ed era l Republic of Germ any

M r. E .E . Smith,R adiologica l P rotection S ervice,M edical R esearch Council and M inistry o f Health, Sutton, Surrey,United Kingdom

S cien tific S ecre ta r ies

M r. E. W allauschekEuropean Nuclear E nergy A gency (ENEA)

M r. J. Mehl (until June 1965)M r. S. Somasundaram (from Septem ber 1965) International Atom ic E nergy A gency (IAEA)

2


1. EXPLANATION OF TERMS USED

For the purposes of these Standards, the following explanations of terms used are given:

(1) O rd in a ry t im e p ie c e s

Wrist or pocket watches or clocks, which contain a quantity of radioactive material acceptable for ordinary use.

(a) Wristwatches: Under normal conditions of use, wristwatches are worn on the wrist.(b) Pocket watches: Watches worn on the individual, other than on the wrist.(c) Clocks: Timepieces that are not worn on the individual.

(2) S pecia l t im e p ie c e s

Timepieces usually worn by the individual, containing quantities of radioactive material to produce greater luminosity necessary for special purposes.

(3) T ota l a c t iv i ty o f a t im e p ie c e

The total activity of the radioluminous paint present in a timepiece, regardless of which parts are luminized.

(4) A v e r a g e a c t iv i ty o f a t im e p ie c e

The average of the total activities of the timepieces taken at random from a given batch.

(5) B a tch

Timepieces or components of timepieces of a particular type produced within a given factory from the beginning to the end of a production cycle, without entailing changes in methods of production, materials of construction, or type and brand of radioluminous paint.

3


(6) A ctivity o f radium-226

The activity of radium-226 in equilibrium with its daughter products of short half-life.

(7) A c t iv ity o f p r o m e th iu m -147

The activity of promethium-147 is established under the a s sumption that the presence of radioactive contaminants does not significantly affect the radiological characteristics on which is based the total activity permitted per timepiece.

(8) R ad iologica l quantities and units

Where reference to radiological quantities and units is made, the definitions and symbols comply with those given by the ICRU1.

2. SCOPE

2. 1 . These Standards shall apply to timepieces containing com ponents bearing radioluminous paint which are intended for use by individual members of the public.

2. 2. The aims of these Standards are to ensure that:(i) Users of radioluminous timepieces are exposed to as little

. ion izin g radiation a s p r a c tic a b le ;(ii) Users of radioluminous timepieces are not exposed to radi

ation in excess of the maximum permissible levels.laid down in the basic radiation protection standards2 of the Agencies, which are based on ICRP recommendations;

(iii) The contribution to the dose received by the whole population from the use of radioluminous timepieces is kept within the limits adopted by the appropriate national authority.

1 At present: ICRU Report No. 10a "Radiation Quantities and Units", National Bureau of Standards Handbook 84, Washington D. C. (1962).

2 Basic Safety Standards for Radiation Protection, Safety Series No. 9, IAEA, Vienna (1962) Revised Edition, IAEA, Vienna (1967).

Radiation Protection Norms, European Nuclear Energy Agency of the Organization for Economic Co-operation and Development, Paris, 1962 (at present under revision).

4


2. 3 . These standards shall not constitute an exemption from the obligations of notification, declaration, registration and/or licensing in connection with the manufacture, maintenance, repair, storage, transport, import/export and disposal of timepieces containing components bearing radioluminous paint. Such operations shall be carried out in accordance with national and international norms for radiation protection.

2.4. These Standards are not intended to cover radiation protection aspects for special timepieces containing quantities of radioactive material which exceed the limits set out in these Standards; these shall be subject to the jurisdiction of the appropriate national authority.

2. 5. These Standards are not intended to cover radiation protection aspects relevant to workers in the radioluminous paint and watch industry3. Nor are they intended to cover watchmakers who repair and maintain radioluminous timepieces, who should be informed of the potential hazards involved and should observe appropriate protective measures.

3. GENERAL REQUIREMENTS

3.1. Selection of radionuclides for use in luminous paints, and limitation of activity levels for dials and hands of timepieces shall be governed by consideration of:

(i) The quantity of a radionuclide necessary to obtain the re quired luminosity of the dials and hands of a timepiece;

(ii) The external radiation doses normally received by the user from the activity referred to under (i);

(iii) The doses that would result from internal radiation if particles of the radioactive luminous paint were ingested or inhaled,

3 These aspects have been dealt with in the ILO "Manual of Radiation Protection. Part V. Guide on Protection against Ionizing Radiation in the Application of Luminous Compounds", ILO, Geneva (1964).

5


with a view to minimizing exposure from external radiation and to keeping the potential risk of exposure from internal radiation as low as possible, for both individual members of the public and the whole population.

3.2. Apart from the considerations referred to in 3.1, the quantity of radioactive material in a timepiece shall be governed by the consideration of whether it is for ordinary or special use. Timepieces shall therefore be classified as:

(a) Timepieces for ordinary use (ordinary timepieces);

(b) Timepieces for special use (special timepieces).

Ordinary timepieces shall be free for general distribution, which will be wide and uncontrolled. Consequently the quantity of radioactive material they contain must be limited to amounts that will satisfy the aims of these Standards as set out in paragraph 2.2. Special timepieces are designed for uses for which greater luminosity than is necessary for ordinary timepieces is required. Their distribution is limited and their use is, in general, restricted to a limited period of time. Therefore, the quantity of radioactive material in special timepieces can be greater than is acceptable for ordinary timepieces and still satisfy the aims of these Standards as set out in paragraph 2.2.

3 .3 . The watch casing (case and transparent cover) shall be such that under normal conditions of use:

(i) The user is protected against direct contact with radioactive dials and hands;

(ii) Low-energy beta-radiation is effectively absorbed by the ' watch casing.

3.4. The adhesion of radioluminous paint to dials and hands of the timepieces shall be such that, under normal conditions of use, it remains fixed on these components.

6


4. SPECIAL REQUIREMENTS

4 . 1 . Radionuclides permitted for use in luminous paint for dials and hands of tim epieces4.

4 . 1 . 1 . Subject to 4.1. 3, the use of radionuclides in luminous paint for dials and hands of ordinary and special timepieces shall be restricted to:

(i) Tritium (3H)

(ii) Promethium-147 (141Pm)

(iii) Radium-2 2 6 (226Ra)

However, the use of 3H and 141Pm should be preferred as far as possible.226Ra shall not be used for pocket watches, regardless of

whether these are ordinary or special timepieces.

4. 1.2. The luminous paint used for the dials and hands of a timepiece should be activated with one and the same radionuclide5.

4. 1 . 3 . Any other radionuclide considered for use in timepieces shall be subject to a separate decision by the appropriate national authority based on the general requirements set out in paragraph 3.1. - 3. 4 6 . The appropriate national authority shall inform the international organizations concerned of such decisions.

4 See Annex I.

5 In the exceptional case where the use of more than one radionuclide in a timepiece isnecessary the sum of the ratios of the amount of each radioisotope contained in the timepiece tothe respective total permissible amount (as established in paragraph 4.2) shall not exceed the unity:

(X/LX + Y/Ly + . . . ) s 1

X, Y represent the activity of the radionuclide actually used.Lx, Ly represent the respective maximum permissible total activity.

6 The Agencies are prepared to consider the amendment of the list of radionuclides specified for use at a later stage, when new scientific information is available.

7


4.2. Total activity of radionuclides permitted per timepiece7.

4 . 2 . 1 . Ordinary timepieces

For ordinary timepieces, the total activity of radionuclides permitted according to 4 . 1 . 1 shall be limited as follows:

(a) Wrist watches

Radionuclide Average Maximum

3H 5 mCi 7.5 mCi

147 Pm 100 )iC i 150 (jCi

226 Ra 0.1 fiCi 0.15 (iCi

(b) Pocket watches


3H 5 mCi 7.5 mCi

147 Pm 100 ltd 150 (iCi

(c) Clocks


3 H 7.5 mCi 10 mCi

147 Pm 150 jnCi 200 fjCi

226 Ra 0.15 (iCi 0.2 nCi

7 See Annex II.


4 . 2 . 2 . Special tim epieces

For special timepieces, the total activity of radionuclides permitted according to 4 . 1 . 1 shall be limited as follows:

Radionuclide Maximum total activity

3H 25 mCi

147 Pm 0.5 mCi

m Ra8 1.5 MCi

4. 3. A d h esion o f ra d io lu m in ou s paint on d ia ls and hands

4.3. 1. The degree of adhesion of radioluminous paint on dials and hands should be subject to tests. The adhesive agent of the paint should provide adhesion on the painted surfaces in a manner which will withstand bending, vibrating and changes of temperature normally incident to the use of timepieces;

4 . 3 . 2 . The radioactive material should be bound in the luminous compound in a not readily soluble form, either by means of its chemical composition or with the help of a binding agent.

4 . 4 . C asing

Timepieces with dials and/or hands bearing radioluminous paint shall be enclosed in a case, the transparent cover of which must have a thickness equivalent to not less than 50 m g/cm 2 at any point. The casing and the transparent cover should be strong enough to withstand conditions normally incident to use and conditions incident to minor accidents.

4 . 5 . M arking

4, 5 . 1 . Ordinary timepieces

Ordinary timepieces do not require a special marking.

8 Not perm itted for pocket watches (see paragraph 4 .1 .1 ) .

9


Special timepieces must bear a specific marking on the dial to adv ise the watchmaker and the user of their special nature, and to permit that the appropriate national authority may take measures for the introduction of adequate systems of notification, declaration, registration and/or licensing if so deemed necessary.The marking should be as follows:

4 . 5 , 2 . Special tim ep ieces

Radionuclide Marking To indicate upper limit of activity as

Tritium "T 25" 25 mCi 3H

Promethium-147 "Pm 0.5" 0.5 mCi 147Pm

Radium-226 "Ra 1.5" 1.5 pCi “ Ra

4 . 6. T&sts

Special requirements as set out in paragraph 4. 1 to 4. 5 shall be subject to tests; these shall be carried out under the jurisdiction of the appropriate national authority. Recommendations for control procedures for radioluminous timepieces are given in the Appendix.

4. 7 . E x em p tio n fr o m n o tif ic a t io n , r e g is t r a t io n a n d / or l i c e n s in g

Provided that the detailed requirements listed above are met, the use of ordinary watches shall be exempted from notification, declaration, registration and/or licensing. Unless decided otherwise by the appropriate national authority, the exemption from notification, by the appropriate national authority, the exemption from notification, declaration, registration and/or licensing is extended to special timepieces containing tritium, but these requirements may be advisable in the case of promethium-147 and in particular of radium-22 6.

10


CONTROL PROCEDURES FOR RADIOLUMINOUS TIMEPIECES

1.1. Tests are necessary in order to ensure that the special re quirements laid down in the Standards for Radioluminous Timepieces are met. By these Standards, it is necessary to ensure that:

(i) The use of radionuclides in luminous paint for dials and hands of timepieces is restricted to selected radionuclides (3H, 147Pm or 226Ra);

(ii) The total activity per timepiece is limited;(iii) Marking of dials is applied if the total activity of a tim e

piece exceeds the activity levels set out for ordinary timepieces;

(iv) The adhesion of radioluminous paint to dials and hands of timepieces shall be such that, under normal conditions of use, it remains fixed on these components.

(v) The thickness of the casing is not lowered below minimum thickness values.

The aim of the recommended tests is therefore to ensure compliance with the provisions of the Radiation Protection Standards. They do not relate to the quality of timepieces or their components.

APPENDIX

1. INTRODUCTION

1.2. It is not practicable to include in a recommendation of an international character, tests of all the properties of luminous paints which it might be of interest to examine. A minimum control programme is therefore proposed in order to determine compliance with the requirements as previously listed.

The tests may be* carried out on the components or, if possible, on the complete timepiece. Besides the minimum control programme, it may be advisable, however, that producers perform additional quality tests on the paints or painted hands and dials, before they are used in the production of timepieces.

1.3. The control procedure should be carried out under the jurisdiction of the appropriate national authority and should comprise both prototype tests and quality control. There may be differences

11


in the organization of control procedures from country to country, depending on different existing regulations. Details of the organization of the control are therefore left to be decided by the appropriate national authority, but it is recommended that it should be conducted on a common basis according to the recommendations given in the Minimum Control Programme below.

1.4. Exemption from these regulations may be granted by the appropriate authority if the producer can guarantee that the requirements in the Minimum Control Program m e have been fulfilled.

2. MINIMUM CONTROL PROGRAMME

2. 1. E xplanation o f t e r m s

(a) Prototype tests are tests to determine that the combination of the radioluminous paint, materials of construction and methods of manufacture are such that the timepiece or its components meet the requirements of the Standards.(b) Quality control comprises tests to ensure that the paint, components and manufacturing methods are the same as those used to produce the prototype timepiece or component, and the quality of the product is the same as the quality of the timepiece or component on which the prototype tests were conducted.

2. 2. P ro to ty p e te s ts

For each batch, the following tests shall be conducted in se quence on five timepieces of the appropriate components. If the batch is less than 20, tests need be conducted on only one timepiece.

2.2. 1. Type of nuclide, activity and marking

(a) Type of nuclide: It should be determined by standard methods and/or by certification of the supplier of the radioisotope.(b) The activity shall be determined by methods appropriate for the radionuclide9.(c) Marking: Visual inspection.

3 For instance: by m easuring the activity or the luminosity, applying chem ical procedures and other appropriate methods.

12


2 . 2 . 2 . Adhesion, release of activity and solubility

(a) Adhesion: The dials shall be attached to a vibrating fixture and undergo vibration at a rate of between 20 and 30 Hz, and a vibration acceleration of not less than 2 £ for a period of not less than one hour (g is the acceleration due to the earth's gravity). The hands shall be bent over a cylinder of 2. 5 cm diameter.If the length of the hand exceeds 1.5 cm, a larger bending radius up to the length of the hand tested shall be permitted. If, for reasons of special design, bending tests are not practicable, they should be replaced by a vibration test similar to that for dials.After this, appropriate tests should be made to check the firm adhesion of the paints on the dials and hands, i . e. by means of ultra-violet lamps and/or measurement of the activity of the painted components in order to ensure that no significant loss of activity has occurred.(b) Release of activity and solubility for tritium-activated paints: Hands and dials containing tritium-activated paints that have been subject to vibration or bending tests shall be totally immersed in distilled water at 20 ± 2°C for 24 h. The water must stand at least 3 mm above the painted area. The tritium content of the water shall not exceed 5% of the original activity of the tested components,

2 . 2 . 3 . Casing

The transparent cover must have a thickness equivalent to not less than 50 m g/cm 2 at any point.

2. 3. Q uality c o n tr o l x

Quality control procedures shall be used to ensure that the quality of the timepiece or components compares adequately with the quality of those timepieces or components employed in the prototype tests. As a minimum, quality control shall consist of 100% visual inspection to detect cracking or flaking of paint, imperfections in the transparent cover, inadequate markings, etc.

Special control procedures may be set out by the appropriate national authority, which shall take any measures necessary to ensure compliance with the standards. The manufacturer should make any additional tests necessary to fulfil the standards.

13


ANNEX I

SELECTION OF RADIONUCLIDES TO BE USED IN RADIOLUMINOUS TIMEPIECES

1. GENERAL CRITERIA FOR SELECTION

Out of the large number of naturally occurring and artificially produced radionuclides, only those which possess the following properties are technically suitable for use in radioluminous paint:

(i) Emit radiation suitable for producing luminosity in luminous paint, but which do not cause significant deterioration of the phosphor.

(ii) Have a lifetime long enough so that sufficient luminosity is obtained during the lifetime of the timepiece for which they are used.

(iii) Can be readily obtained at moderate costs in the required concentration and quantity.

The selection of radionuclides which can be permitted for use in radioluminous paint for timepieces must take into account the particular requirements of radiation protection which may be summarized as follows:

The quantity of the radionuclide per timepiece required to obtain sufficient luminosity shall be so low that:

(i) The doses which would result from external radiation of the timepiece should constitute only an insignificant fraction of the maximum permissible doses which apply to individual members of the public;10

(ii) The doses which would result from internal radiation if particles of the radioluminous paint were accidentally incorporated should — even under extreme conditions of intake — not constitute a significant radiation hazard.

For convenience of physical surveillance it is also desirable that the radionuclide meets the following requirements:

(i) It can be obtained without significant contamination from other radionuclides.

(ii) It can be bound in the luminous paint so that it does not escape in significant amounts.

10 This fact stresses once again the desirability of using 147Pm and 3H (see point 4 .1 .1 ).

14


(iii) It can be easily measured in quantities which are to be kept under control (e.g. activity handled, surface contamination, concentration in air and water, body burden).

In Table I are listed those radionuclides that have been Vised so far or that have been considered for use. As the following radionuclides are not commercially available, they are not included in the table: 151Sm, 171Tm, 227Ac, 232U, 233U, 237Np, 238Pu, 239pu> 240Pu, 241 pU) 242pu, 244Cm, 246 Cm, 250Cf, 252Cf. 228Ra has beenomitted because it can be obtained only with varying contents of 226Ra.

TABLE I. TECHNICAL DATA OF RADIONUCLIDES CONSIDERED FOR USE IN RADIOLUMINOUS TIMEPIECES

RadionuclideHalf-life

(yr)Type o f radiation

emitted

KrSpecific

gamma-ray emission R cm 2 h mCi

KgSpecific beta-ray emission a rad cm2

h mCi

3 H 12.46 6 - 0

14 C 5.57 X 103 6 - 0

36 Cl 3 .1 X 10 s 6, X - 150

63 Ni 125 e - 0

85 K r/85mRb 10.27 6. r 0.021 140

90Sr/90Y 28 6. 7 0.0017 370

" T c 2.1 X 105 6 - 18

147 P m /147Sm 2.50 e - < 2 .8204 3.57 . 6, X 0.007 160

210 pb 19.4 a. e, 7 0.014 205

226 Ra 1.62 X 10s a, 6 , 7 9.3 580

230 T h 8.0 X 104 7 0.0033 0

241 A m /237 mNp 470 a, 7 0.14 0

a 50 m g/cm 2 absorbent medium.

15


For the assessment of doses from external radiation are listed the specific gamma-ray emission and the specific beta-ray emission of the radionuclides. Doses from internal radiation can be assessed for all the radionuclides included in Table I from data published by ICRP [1],

2. ACTIVITY REQUIRED TO PRODUCE ADEQUATE LUMINOSITY

The basic concept in radiation protection is that all doses be kept as low as practicable and that any unnecessary exposure be avoided. In radiation protection applicable to the use of radioluminous timepieces compliance with the basic concept of radiation protection is best achieved if the activity per timepiece is kept as low as practicable, i . e. not higher than is required to produce adequate luminosity.

• The recognition of hand positions and dial divisions by luminous paint marks depends primarily on the size of the marking, the brightness of the surface11 and the reading distance. The values of minimum brightness listed in Table II were assessed [1] under the assumption that "point marking" is applied and that the spot diameters and reading distances listed in the second and third column

TABLE II. MINIMUM BRIGHTNESS REQUIRED FOR VARIOUS TYPES OF ORDINARY TIMEPIECES

Type of timepiece Spot diameter (mm)

Reading distance (cm )

Minimum brightness (/JL)

Ladies' wristwatches 0 .4 - 0.8 25 0.38 - 1.4

Mens' wristwatches 0 .6 - 1.0 25 0.24 - 0.65

Pocket watches 0.8 - 1.0 25 0.24 - 0.38

Travel alarm clocks 1.0 - 1.5 50 0.44 - 0.97

Large alarm clocks 1.5 - 3 .0 50 0.11 - 0.44

■1 Luminosity is measured in units of brightness. Brightness is measured by the flux emitted per unit emissive area as projected on a plane normal to the line of sight. The unit of brightness is that of a perfectly diffusing surface giving out one lumen per square centimeter of projected surface and is called the lambert (L).

16


respectively apply to the various types of timepieces for which the values are given. It is to be noted that also normal eyesight and adaption of the eye to darkness over a period of 30 min was presupposed in the assessment of the values of minimum brightness. Investigations of the activity required per gram of phosphor to produce a brightness in the range of ljuL, to 100 /uL have been published for 3H, 90S r /90Y, 147Pm, 204^ ancj 226 j a by various authors [2, 3, 4] and by luminous paint manufacturers [6 - 1 2 ]12. On the basis of these values the activity ratio

^ _ activity of beta-em itter/gram phosphorA activity of 226R a/gram phosphor

which corresponds to luminous densities of I to about 10 uL, was assessed [5],

The values of the activity per gram phosphor (ZnS/Ag) required to produce an initial brightness of 1 juL (two months after manufacture) A(0) and the corresponding activity ratios RA(0) listed in columns 2 and 3 of Table III do not make allowance for losses of brightness due to radioactive decay, release of activity and deterioration of the phosphor during the lifetime of the timepiece, and due to the absorption of radiation and visible light in the painted spot. These losses were taken into account via time-dependent loss factors r (radioactive decay) and r) (deterioration of the phosphor and release of activity from the paint), and the time-independent loss factor 6 (loss in the applied condition.as compared with the brightness of the activated natural phosphor in powder form).

The values t(10), rj(10), a(10), A(10) and RA(10) given in Table III were assessed [5] for timepieces with an expected lifetime of 10 yr. The influence of colour additives, which reduce the luminous density to as much as 30% of the uncoloured phosphor, was left out of account, because such colourings conflict with the basic concept of radiation protection. On the basis of the A(10) values given in Table III and

12 It is to be noted that the reported values are not in all cases suitable for comparison. Different phosphors were used and the method of paint preparation and of measurement of luminosity were not standardized. For that reason the calculations of the activities required to produce a luminosity of 1 )iL had to be based on the best possible interpolation from measured data. Therefore, the ratios listed should not be taken as absolute values; they are intended for guidance only in the assessment of the order of magnitude of exposure levels from external and internal radiation and would require correction as more detailed information becomes available.

17


T A B L E III. AC TIV ITY PER GRAM PHOSPHOR (ZnS/Ag) [C i/g ] REQUIRED FOR PRODUCING A LUMINOSITY OF 1 (iL(i) Shortly (2 months) after production of the radioluminous paint: A(0)(ii) 10 yr after production of the radioluminous paint: A(10) = A(0)/cr and the corresponding

activity ratios R A(0), R a(10)

Radionuclide A(0)(Ci/g) ra (° )

Loss factor Total loss o(10)

A(10)(Ci/g) RA(10)

r(10) 7)(10) 6

3H 4 .6 X 10"3 5.3 X 10 3 0.56 0.27 0.18 0.027 1 .7 X 10_1 2.00 X 10 4

14 c 1.9 X 1 0 ‘ 4 2 .2 X 10 2 . 1.00 0.21 0.37 0.078 2 .4 X 1 0 '3 2 .8 X 102

36 Cl 4 .3 X 10 - 5 5 .0 X 101 1.00 0.15 0.50 0.075 5.7 X 10 '4 6 .5 X 10

63 Ni 5 .7 X 1 0 ' 4 6 .7 X 102 0.94 0.25 0.30 0.070 8 .1 X 10 " 3 9 .3 X 102

85 Kr 4 .7 X 1 0 '5 5 .5 X 101 0.52 0.16 0.50 0.042 1.1 X 10 " 3 1 .3 X 102

90 Sr 1 .9 X 10 ' 5 2 .2 X 101 0.77 0.11 0.65 0.055 3 .4 X 10 "• 3.9 X 10

59 T c 1.0 X 10 ‘ 4 1 .2 X 102 1.00 0.16 0.42 0.067 1.5 X 10 ' 3 1 .7 X 102

i” Pm 1.5 X 1 0 -4 1 .7 X 102 0.068 0 .2 0 0.39 0.0053 2 .8 X 10 -2 3 .2 X 103204 4 .3 X 10- 5 5 .0 X 101 0.17 0.16 0. 50 0.013 3 .2 X 10 ' 3 3 .7 X 102

210 pb 3 .9 X 1 0 '6 4.5 0. 71 0.16 0.35 0.040 9 .8 X 10 1.1 X 10

226 Ra 8 .5 X 10-1 1 .0 1.00 0.26 0.38 0.098 8 .7 X 10 1 .0

230 T h 4 .3 X 1 0 '6 5 .1 1.00 0.30 0.35 0.105 4 .1 X 10-5 4 .7

241 Am 3.7 X 10-6 4 .4 1.00 0.30 0.35 0.105 3 .5 X 10 4 .0


values quoted by the dial-painting industry for the quantities of activated phosphor required per timepiece and the minimum luminous densities needed for the various types of ordinary timepieces (see Table II) an assessment was made on the total activity required per timepiece (see Table IV). These values are found to be some three to four times higher for travel alarm clocks and large alarm clocks than for other timepieces.

It should be noted that the values of the total activity of tim epieces listed in Table IV are minimum values. Allowance should be made for higher activities in order to compensate for variation of eyesight, to reduce the time required for adaption of the eye for reading and to compensate for quality variation of the luminous paint. For that reason four times the minimum total activity values which apply to small watches and twice the minimum total activity values which apply to alarm clocks (in these cases variation of eyesight can be compensated by reduction of the reading distance) may be used for guidance in limiting the total activity of ordinary tim epieces. For special timepieces ten times the minimum total activity values which apply to small watches may be considered a reasonable upper limit of the total activity per timepiece. It should be possible that with these activity levels the luminosity can be obtained which is required to permit reading of the time under all the special conditions for which special timepieces are designed.

3. HAZARDS OF EXPOSURE FROM EXTERNAL ANDINTERNAL RADIATION

Owing to more than 60 years of experience with radium, the potential risks of radiation exposure from this element and its daughter products are well understood. Timepieces with luminous paint activated with radium have been in use over the past 50 years and there exists a considerable volume of literature, which gives estimates of radiation doses to the public resulting from the use of radium-activated luminous timepieces. It would seem useful to make use of these data in arriving at comparative estimates of the radiological hazards to the public resulting from the use of luminous timepieces containing the other radionuclides which are listed in Table I.

19


TABLE IV. MINIMUM TOTAL ACTIVITY (mCi) OF VARIOUS TYPES OF TIMEPIECES

Type o f timepieceLadies'

wristwatchesMens'

wristwatchesPocket

watches

Travelalarmclocks

Largealarmclocks

Spot diameter(mm) 0.6 0.8 0.9 1.3 2.3

Total quantity ofphosphor (mg) 4 7 9 18 50

Reading distance(cm) 25 25 25 50 50

Minimumbrightness (jiL) 0.65 0.38 0.30 0.57 0.20

Radionuclide Total activity (mCi)

3H 4 .4 X 10 _1 4 .5 X 10 ~l 4. 6 X 10 1.7 1.7

14 C 6 .2 X 1 0 '3 6 .4 X 1 0 '3 6 .5 X 10 ' 3 2.5 X 10 " 2 2 .4 X 10- 2

36 Cl 1.5 X 10‘ 5 1 .5 X 10 ‘ 3 1 .5 X 1 0 '3 5.9 X 10‘ 3 5 .7 X 1 0 '3

63 Ni 2 .1 X 10‘ 2 2 .2 X 10"2 2 .2 X 1 0 '2 8.3 X 1 0 '2 8 .1 X 1 0 -2

85 Kr 2.9 X 10 "3 2 .9 X 10 ’ 3 3 .0 X 10 '3 1.1 x i o ~ 2 1.1 X 10"2

90 Sr 8 .8 X 1 0 '4 9 .1 X 10"4 9 .2 X 10"“ 3 .5 X 1 0 '3 3 .4 X 1 0 '3

" T c 3 .9 X 10"3 4 .0 X 10"3 4 .0 X 10"3 1.5 X 1 0 '2 1.5 X 10‘ 2

147 Pm 7.3 X 10‘ 2 7.5 X 10‘ 2 7.6 X 10 '2 2.9 X 1 0 '1 2.8 X 10_I204 T j 8 .3 X 10"3 8 .5 X 10 3 8.6 X 10‘ 3 3.3 X 1 0 '2 3 .2 X 10‘ 2210 p b 2 .5 X 10‘ 4 2 .6 X 10"4 2. 6 X 10‘ 4 1.0 X 1 0 '3 9 .8 X lO’ 4

226 Ra 2 .3 X 10‘ 5 2 .3 X 1 0 '5 2.3 X 10'5 8.9 X 10"5 8 .7 X 10‘ 5230 1.1 x i o ' 4 1.1 x i o ' 4 1.1 X 10'4 4 .2 X 10' 4 4 .1 X 10‘ 4

241 Am 9 .1 X 10"5 9 .3 X 10’ 5 9 .4 X 10‘ 5 3 .6 X 10‘ 4 3 .5 X 10"4

20


The only data at present available on the doses received by various organs as a result of external exposure from timepieces relate to timepieces containing 226Ra [12 - 22], Experimental in-' vestigations have shown that the radiation doses are closely bound up with the habits of the user and the design of the timepiece. Values for specific beta- and gamma-ionization (see Table I) and the re lative activity values R A(10) (see Table III) are therefore used here in assessing the external exposure to be expected from the use of the radionuclide X under consideration, relative to the exposure which must be expected if 226Ra is used13. In calculating the Kg values it was assumed that beta-radiation is absorbed by 50 mg/cm2 (minimum thickness of the transparent cover). Contributions from bremsstrahlung and absorption in air were ignored. The decay of the radionuclide over the lifetime of the timepiece is taken into account by introducing the integral mean value of the specific beta- and gamma-ray emission over that period. The relative dose values shown in Table V correspond to the relationship

3 . 1 . External exposure

R6 r (10) =

i - 0 .693t/TpR (10) X K X 6 X

[Kg v ] 226Ra

R a (1 0 ) is the ratio of the specific activity of the given radionuclide (Ci/g of phosphor) required to produce a luminosity of 1 /jL after a period of 10 years to the specific activity of 226Ra required to produce a luminosity of 1 nL after a period of 10 years.

Rg(10), Ry(10) is the ratio of the external beta or gamma radiation exposure received over a period of 10 years from a specific activity RA(10) of the given radionuclide to the external beta or gamma radiation exposure received over a period of 10 years from unit specific activity of 226Ra.

The values of Rg and Rv can only serve as a rough guide in the assessment of surface doses. The assessment of the doses received

13 There exist some uncertainties with respect to the Rg value of 226Ra. If it is assumedthat 2N>Bi (RaE), daughter product of 210Pb (RaD) (TD = 19.4y) is not present, then the calculated

rad cm 2 rad cm2value is Ko = 370 -------------- In calculating the dose ratio the value Ko = 400--------- rr was usedp h mCi p h mCifor 226Ra.

21


TABLE V. EXTERN AL EXPOSURE FROM BETA-RADIATION AND GAMMA-RADIATION (See text for definition o f Rg and Ry)

Radionuclide R6(10) 1^(10)

3 H 0 0

14 C 0 0

36 Cl 24 0

63 Ni 0 0

85 Kr 33 2.1 X 1 0 '1

90 Sr 32 6.3 X 10‘ 3

99 Tc 7.7 0

w Pm ~0 0

204'j'j 66 1 .2 X 10"1210 pfa 4.8 1 .4 X 10 "2

226 Ra 1.0 1.0

230 Th 0 1.7 X 10 "3

241 Am 0 6.0 X 10"2

by specific organs would require more elaborate calculations whereby in particular the exposure geometry and the absorption of the radiation in tissue would need detailed consideration. It can be seen from Table V that exposure of the user of a timepiece from beta radiation and gamma radiation can be reduced to zero level if aH, 14C, 63Ni or 147Pm are used. In the case of "T c , if the thickness of the absorbent medium is assumed to be 75 mg/cm^, the value of Rg would be barely distinguishable from zero. However, if 36C1, 85Kr, 90Sr or 204x 1 were used, then the exposure from beta radiation would be significantly (by factors between 20 and 7 0) higher than that which would result from use of 226Ra. A beta dose still higher by a factor of 5 would result from the use of 2i°Pb. In case of 230xh and 24iAm there would not exist exposure from beta radiation and the doses from gamma radiation could be considerably reduced.

22


3 . 2 . Internal exp osu re

Table VI shows dose equivalent values (rem) per unit activity (^Ci) taken up by adults (standard man). The values were calculated for various modes of uptake of soluble and insoluble materials on the basis of the values published by the ICRP [1] for metabolic behaviour, effective energy and organ weights. For effective energies whose effective half-lives are long in comparison with the expected exposure times (90Sr, 226Ra, 230Th and 241 Am) the dose which would be received after a period of 50 yr is not taken into account. The doses for uptake of soluble radionuclide through wounds (Dws) and for the inhalation of the insoluble radionuclide (Djj) correspond to Fairbairn's data [12]. The values for the ingestion of soluble radionuclides (Dqs) and the inhalation of soluble radionuclides (DiS ) were calculated on the basis of the following relationships:

D os = f i x Dws

DjS = fa/fw X Dos

where ^ = fraction of the radionuclide which passes from the gastrointestinal tract to the blood

fa = fraction of the radionuclide which reaches the reference organ following inhalation

fw = fraction of the radionuclide which reaches the reference organ following ingestion.

The dose values for ingestion of insoluble radionuclides (D01) were obtained from the formula

19. 2 X EE (RBE)JJoi " m

where E E (RBE) = effective energy for the reference organ area of the gastrointestinal tract, and

m = mass of the reference area of the gastrointestinal tract (lower large intestine).

The doses given in Table VI together with the relative activity values Ra (Table III) provide a basis for the assessment of the relative internal radiation exposure, according to the mode of uptake for the radionuclides under consideration.

23


TA B L E VI. DOSE EQUIVALENT (rem) PER UNIT A C TIV ITY (nCi) TAKEN INTO THE BODY FOR ADULTS (standard man)

Radionuclide DWS(rem //iCi)

Critical3organ fi Do s

(rem/jiCi)lafw

DlS(rem /fiCi)

D b ^Ol(rem/|iCi)

DIIC (rem /(i Ci)

3H 2 .4 X 1 0 '4 body tissue 1.0 2 .4 X 10‘ 4 1.0 2 .4 x 10~4 1.3 X 10‘ 3 i . o x io ' 2

14 C 2 .8 X 1 0 '3 bone 1.0 2.8 X 10-3 0.80 2 .2 X 10‘ 3 6.9 X lO '3 6 .1 X 1 0 '2

36 Cl 7.0 X 1 0 '3 whole body 1.0 7.0 X 1 0 '3 0.75 5 .2 X 10‘ 3 3 .3 X 10 -2 2 .9 X 10

63Ni 2 .4 X 1 0 '1 bone 0.3 7 .2 X 10"2 1.33 9 .6 X 10‘ 2 2 .7 X 10‘ 3 2. 4 X 10‘ 2

8SKr - - - - - - 2 .8 X 1 0 '2 2 .6 X 1 0 '1

so Sr 9 .0 X 10 bone 0.3 2.7 X 10 1.33 3 .6 X 10 1. 4 X 1 0 '1 1 .2

" T c 6 .0 X 1 0 '3 kidneys 0 .5 3 .0 X 10-3 1.0 3 .0 X 1 0 -3 1 .2 X 10‘ 2 1 .1 X 1 0 '1

147 Pm 7.0 X 1 0 '1 bone 10 - 4 7.0 X 10 - 5 2 .6 X 103 1 .8 X 1 0 -1 8 .8 X 10 ' 3 7 .0 X 10 ‘ 2204'j'j 3 .0 X 1 0 '! kidneys 0.45 1.4 X 10 "2 1.04 1 .5 X 10 ‘ 2 3 .2 X 10 ‘ 2 2 .6 X 10 _1

2ioPb 2 .0 X 10z bone 0.08 1.6 X 10 4 .0 6 .4 X 10 1. 2 X 10 _1 2 .8 X 10

226 Ra 1.0 X 10 3 bone 0.3 3 X 10 2 0.75 2 .3 X 102 5.9 X 1 0 - 1 1 .3 X 102

230Th 1.1 X 105 bone 10 1.1 X 10 2.6 X 103 2 .9 X 104 6 .0 X 10 "2 5 .4 X 10

M1Am 9 .0 X 103 bone 10- 4 9.0 X 10"1 2 .5 X 103 2 .3 X 103 7. 7 X 10 " 2 6 .5 X 10

a These values relate to D ^g, Dpg and DIS k The critical organ is the lower large intestine c Critical organ is the lung


The relative d oses

(•^A ^O I^XK q1 = ^ 226R a ’ ( in g e s t io n in in so lu b le f o r m )

( R a X Djr )XRn = — ) 226Ra ’ (inhalation in insoluble form)

( R A X D f

(Dos ■A OS 'X— 226Ra ’ (ingestion in soluble form)

(..a x d )x .R1S = — — j ~2~2^Ra ' 1 (inhalation in soluble form)

(r a x d ws) xRwq = — , „ogT,— » (uptake through wounds in soluble form)

(DWs' Ka

show the factor by which the dose corresponding to absorption of luminous paint from a timepiece containing radionuclide X differs from that due to the absorption of a similar amount of luminous paint containing a 226Ra activated phosphor.

All these dose ratios are based on the soluble form of 226Ra, because it must be assumed that 226Ra activated paints produced so far cannot be considered completely insoluble [13],

The values calculated from activity ratios which apply- to timepieces with a lifetime of 10 years are given in Table VII. The absorption of insoluble materials through wounds has not been considered because it can be assumed that most of the material is removed from the wound during treatment and therefore does not reach the critical organ.

It can be deduced from Table VII that

(i) The dose from internal radiation in the case of ingestion would be less for each of the available radionuclides than for soluble 226Ra, provided that the radionuclide is used in the insoluble form. ' In the case of 22®Ra the dose from internal radiation would result only in about 1/500 of the dose to be expected from use of the soluble product.

(ii) With the available radionuclides the dose from internal radiation caused by inhalation of insoluble radionuclides, except 2i°Pb, would be less than or comparable to the dose to be expected from the use of z26Ra in its soluble form.

25


T A B L E V II. R E L A T IV E V A L U E S O F T H E D O SE F R O M IN T E R N A L R A D IA T IO N (s in g le in ta k e )(S ee te x t f o r d e fin it io n o r q u o t ie n ts )

Radionuclide R oi(10) -R n (10) RogdO) RIS(IO) RWS<10>

3H 8.5 X 1 0 '2 8 .5 X 1 0 '1 1 .6 X 10’ 2 2.0 X 10‘ 2 4. 7 X 10-3

14 C 6 .4 X 10‘ 3 7 .4 X 10"2 2 .6 X 1 0 '3 2 .7 X 10‘ 3 7.8 X 10‘ 4

36 Cl 7.2 X 1 0 '3 8 .3 X 10rZ 1 .5 X 1 0 '3 1.5 X 10r3 4 .6 X 10 '4

°N i 8 .4 X 1 0 '3 9 .7 X 10 -2 2 .2 X 1 0 '1 3 .9 X 10’ 1 2 .2 X 10 '1

85 Kr 1.2 X 1 0 '2 1 .5 X 10 -1 - - -

90 Sr 1.8 X 10"2 2 .0 X 1 0 '1 3.5 1.5 X 10 3.5

99 Tc 6.8 X 1 0 '3 8 .1 X 10‘ 2 1.7 X 1 0 '3 2 .2 X 10"3 1.0 X 10-3

147 Pm 9.3 X 1 0 '2 9 .7 X 1 0 '1 7 .5 X 10‘ 4 2 .5 2 .2

204 72 3,94 X 1 0 '2 4 .2 X 1 0 '1 1.7 X 1 0 '2 2 .4 X 10"2 1.1 X 1 0 '2

Z10pb 4 .4 X lO-3 1.3 5.9 X 10_1 CO 2 .2

226 Ra 2 .0 X 1 0 '3 5.7 X 1 0 '1 1.0 1.0 1.0

230 xh 9 .4 X 10‘ 4 1.1 1. 7 X 10 -1 5.9 X 102 5.2 X 102

“ ‘ Am 1.0 X 1 0 '4 1.1 1.2 X 10‘ 2 4 .0 X 10 3 .6 X 10

(iii) E xcept in the ca se o f 90Sr, the dose fro m internal radiation a fter in gestion o f the so lub le fo rm o f the availab le rad ion u clides would be le s s than the d o se to be ex p e cte d i f so lu b le 226Ra w e re u sed .

(iv ) W hen the a v a ila b le r a d io n u c lid e s a r e u sed , the d o s e fr o m in te rn a l ra d ia tion re su lt in g fr o m in ha lation o f the so lu b le r a d io n u c lid e s (w ith the e x ce p t io n o f 90Sr, 210P b, 230Th and 24iAm ) w ou ld be le s s than the d o s e to be e x p e cte d fr o m the u se o f s o lu b le 226R a.

(v) W ith the e x cep tion o f 90Sr, 147P m , 210Pb, 230Th and 241 A m , the ' d o s e f r o m in te rn a l ra d ia tio n r e s u lt in g fr o m uptake o f r a d i o

n u c lid e s in so lu b le fo r m through w ounds w ould be le s s than the d ose to be ex p ected fr o m the u se o f so lu b le 226Ra.

(vi) 226Ra cou ld on ly be c o n s id e re d le s s dangerous than oth er r a d io n u c lid e s i f it cou ld be kept in in so lu b le fo r m in ra d io lu m in ou s p a in ts .

26


4 . CO NCLU SIO N S

The p r im a ry o b je c t iv e o f the s e le c t io n o f ra d ion u clid es should be to preven t f o r e s e e a b le r is k s , su ch a s e x p o su re fr o m ex te rn a l r a d ia tion . E x tern a l e x p o su re fr o m t im e p ie c e s can be kept at z e r o le v e l if 3H, 14C, 63Ni o r 147Pm are used and at in sign ificant le v e ls i f 230Th o r 241 A m a re u sed . T h e r e fo r e , th e se ra d io n u c lid e s w ould be su itab le fo r use in tim e p ie ce s p rovid ed that th ere do not ex ist sign ificant r is k s o f in te rn a l ra d ia tion e x p o s u re in c a s e o f an a c c id e n t . In the c a s e o f 3H, l4C , 63Ni and 147P m th e re do not e x is t su ch e x c e s s iv e high r isk s r e g a r d le s s w hether so lu b le o r in so lu b le m a te r ia l is used. H ow ever , in the c a s e o f 230Xh and 241A m su ch r is k s w ould e x is t i f the m a te r ia l w e re to be in ha led o r in co r p o r a te d th rough w ounds in it s so lu b le fo r m . O w ing to the r e la t iv e ly h igh c o s t s a n d /o r ow ing to p r o b le m s in the p ro d u c tio n o f the r e q u ir e d q u a n titie s and c o n cen tra tion s o f 14C and 63Ni lim ited p r a c t ic a l e x p e r ie n ce o f th e ir use fo r rad iolum inou s paint is a v a ilab le . T h e re fo re , a d e c is io n whether the use o f th ese ra d ion u clid es in rad io lu m in ou s paint fo r t im e p ie ce s can be re co m m e n d e d m u st be p o s tp o n e d u n til m o r e e x p e r ie n c e is obtained . T h is le a v e s a s ra d io n u clid e s w hich can be recom m en d ed fo r use in t im e p ie c e s

3H and 147P m .

A s r e g a rd s 226Ra it is a p p re c ia te d that the e x p o su re r is k s a re w e ll u n d erstood and can w e ll be kept u nder c o n t r o l . T he e x p o su re le v e ls f r o m b e ta - and g a m m a -r a d ia t io n and ra d o n le a k a g e d o not p resen t a s ig n ifica n t h aza rd i f the to ta l a c t iv ity is kept at le v e ls w hich a re su b je ct to a d e ta iled study in A nnex II o f th is m anual and i f ad equ ate m e a s u r e s a r e taken w h ich p re v e n t unduly h igh radon leakage. Taking into accoun t the w orldw ide use o f radium fo r ra d io - lu m in ou s paint in t im e p ie c e s du rin g a p e r io d o f about 50 y e a r s , w h ich has not led to a s ig n ifica n t con tr ib u tion to the e x p o su re o f hum an b e in g s [14 ], fu rth er u se o f 226Ra can be p e rm itte d .

R E F E R E N C E S T O ANNEX I

[ 1] Recommendations of the International Commission on Radiological Protection, Report of Committee II on Permissible Dose from Internal Radiation, Pergamon Press (1959).

[2 ] WALLHAUSEN, C. W., Use of Radioisotopes in the Production of Self-Luminous Compounds, Proc. UN Int. Conf. PUAE 15 (1955) 307-309.

27


[3 ] HEUSINGER, H., RAU, H., Producing luminescence by beta-radiation of tritium, Kerntechnik3 (1960) 67-70 (in German).

[4 ] VEIT, W., Investigation on luminous paints activated by Pm-147, Kerntechnik 5 (1963) 221-224 (in German).

[5 ] MEHL, J. G., The choice of Radionuclides for Luminous Paints in Watchmaking Industry, Atomkemenergie 3 /4 (1965) 115-126 (in German).

[6 ] Information sheet on radium activated luminous paint, Radium' Chemie Teufen/AR, Switzerland (1961) (in German).

[7 ] Information sheet on promethium activated luminous paint, kadium-Chemie Teufen/AR, Switzerland (1963) (in German).

[8 ] Trilumin, luminescent material, Westo G. m. b. H ., Stuttgart (1963) (in French).[9 ] Technical information sheet on Prosilux-P luminescent paint, Buchler&Co., Braunschweig

(1964) (in German).[10] Technical information sheet on Prosilux-R luminescent paint, Buchler&Co., Braunschweig

(1964) (in German).[11] Luminosity and activity of Dainippon Sinloihi Co. Ltd. luminescent paints: Atomloihi-T;

Atomloihi-Pj Atomloihi-R. (Personal communication).[12] FAIRBAIRN, A., "The classification of radioisotopes for packaging" in Regulations for the

Safe Transport of Radioactive Materials: Notes of Certain Aspects of the Regulations, Safety Series No. 7, IAEA, Vienna (1961).

[13] HALIK, J., Contribution to radiotoxicity estimation of luminous radioactive paints, Pracovni Lekar 15 (1963)419-422.

[ 14] Report of the United Nations Scientific Committee on the Effects of Atomic Radiation,New York (1962).

BIBLIOGRAPHY (in date o r d e r )

LIBBY, W.F. Dosages from natural radioactivity and cosmic rays, Science 122 (1955) 57-58.

NATIONAL RESEARCH COUNCIL, The Biological Effects of Atomic Radiation, NRC, Washington (1956).

GLASER, G., Radiation from luminous dials and its effects, Feinwerktechnik 61 (1957) 3pp.(in German).

GLASER, G ., Radiation from luminous dials, Die Uhr 23 (1958) 2pp. (in German).

SEELENTAG, W., KLOTZ, E., Radiation exposure of the public from luminous dials of timepieces, Strahlentherapie 110 (1959) 606-621 (in German).

BINKS, W., MARLEY, W .G ., "Occupational exposure to radiation in the United Kingdom and its contribution to the genetically effective dose1', in The Hazards to Man of Nuclear and Allied Radiations. A second report to the Medical Research Council, HMSO CMND. 1225 (1960) Appendix B., 120-128.

28


JOYET, G., MILLER, M ., The radiation dose from luminous dials in Switzerland, Experientia 16 (1960) 342-346 (in German).

EIKODD, A. et al., Radioactivity of luminous watches and estimation of dose to wrist and the gonads, Phys. Med. Biol. 6 (1961) 25-31.

WEISS, H. M ., Radioluminous paints and related questions concerning radiation protection, Jahrbuch der Dtsch. Ges. f. Chronometrie 13 (1962) 108-112 (in German).

SEELENTAG, W., SCHMIER, H., Radiation exposure from luminous watch dials, Radiol. Hlth Data (1963)209-213.

JOYET, G ., Radiation protection and radioactivity of luminous dials, Neue Zurcher Zeitung, Beilage Technik, 17. 4. 1963 (in German).

29


ANNEX II

R A D IA TIO N P R O T E C T IO N CON SIDERATION S AND D E T E R M IN A T IO N O F M AXIM U M PER M ISSIB LE

A C T IV IT IE S OF RA D IO N U CLID ES RE CO M M EN D ED F O R RADIOLUM INOUS T IM E P IE C E S

I. P O T E N T IA L H A ZA R D S RE SU LTIN G F R O M TH E USE OF RADIOLUM INOUS T IM E P IE C E S

1. R a d io lu m in ou s t im e p ie c e s a r e s o u r c e s o f r a d io a c t iv ity w h ich m ay e x p o se in d iv idu al m e m b e r s o f the popu lation and, to so m e e x tent, the population as a w hole, to ex tern a l radiation on the one hand in n orm a l con d ition s o f use, and to the p o s s ib le r isk o f in terna l c o n tam ination o f the other, when p rotection is no lon ger ensured against an esca p e o f rad ioa ctive m a teria l o r contact with such m a teria l. P erm a n en t e x te rn a l ir ra d ia t io n due to and y r a y s is p ro d u ce d by t im e p ie c e s b ea rin g rad io lu m in ou s paint activa ted by rad iu m . If the w atch g la s s is r e m o v e d , e x te r n a l ir r a d ia t io n is a ls o p r o d u c e d by /3 -ra y s in the c a s e o f p r o m e th iu m -147.2. T h e a c t iv ity p r e se n t in a t im e p ie c e w ith a r a d io lu m in o u s d ia l m u st be a s low a s p r a c t ic a b le and, in any event, lo w e r than the am ount o f ra d io n u clid e w h ich w ould ca u se the c r i t i c a l o rg a n to r e ce iv e the m axim um p e r m is s ib le d ose in c a se o f acc id en ta l contam in ation in the m ost u n favou rable con d ition s . Under n orm a l con d ition s o f u se , the d o s e r e su lt in g fr o m the p r e s e n c e o f r a d io n u c lid e s in

-t im e p ie c e s should on ly con stitu te a m in o r fra c tio n o f the m a xim u m p e r m is s ib le d ose fo r e x p o su re o f in d iv idu al m e m b e rs o f the popu la tion . T h is r e d u c e s the r a d io is o to p e s e lig ib le fo r u se in the m an u fa c tu re o f lum in ou s t im e p ie c e s - both fr o m the health and fr o m the cu rre n t te ch n ica l standpoint - to a v e r y sm a ll n um ber, n a m ely t r i tium , p r o m e th iu m -147 and ra d iu m -2 2 6 . (See Annex I).3. H ealth co n s id e ra tio n s m ust take in to accoun t the d o s e s actu a lly r e c e iv e d fr o m the u se o f t im e p ie c e s , the con tr ib u tion o f the d o s e s r e c e iv e d to the g e n e t ica lly s ign ifican t d ose o f the population and the d o s e s which cou ld p o ss ib ly be re ce iv e d by the individual u se r in ca se o f an a c c id e n t. A p a rt f r o m the a c t iv ity in a t im e p ie c e , the d o s e s a c tu a lly r e c e iv e d w ill la r g e ly depend upon the p e r io d du rin g w hich the t im e p ie c e is u sed .4. F o r the a s s e s s m e n t o f the g e n e t ic a l ly s ig n if ic a n t d o s e , the num ber o f u se rs b e co m e s a v e ry im portant fa c to r . F o r that reason .

30


when co n s id e r in g the health standpoint, sep ara te co n s id e ra tio n w ill be r e q u ire d f o r o r d in a r y t im e p ie c e s , w h ich a re u sed co n tin u o u sly by la rg e g rou p s o f the population , and fo r s p e c ia l t im e p ie c e s w hich a re n orm a lly u sed fo r lim ited p e r io d s by a lim ited num ber o f people . H o w e v e r , it is a n tic ip a te d that the c o n tr ib u t io n to the g e n e t ic a lly s ign ifican t d ose o f the population o f le s s than 100 m re m p er g e n e ra tio n (s e e a ls o S e c tio n II o f th is A n n ex), r e s u lt in g f r o m the u se o f o rd in a ry ra d iu m -a ct iv a te d t im e p ie c e s w hich m eet the Standards set out in th is m anual, m ay se e m a cce p ta b le by a ll national au th orities .5. A s c o n c e r n s s p e c ia l t im e p ie c e s , the im p o r ta n c e o f the c o n tr ib u tion to the g e n e t ica lly s ig n ifica n t d o s e o f the popu la tion cannot be a s s e s s e d w ithout a d e ta ile d study o f the p a r t ic u la r s itu a tion in the c o u n try c o n c e r n e d . T h e r e fo r e , though e x p o s u r e r a te s o f e x tern a l rad iation fr o m sp e c ia l t im e p ie c e s can be a s s e s s e d , it cannot be evaluated w hether th ese ex p osu re ra tes would not resu lt in s ig n ifica n t co n tr ib u t io n s to the g e n e t ic a l ly s ig n ific a n t d o s e w ithout in trod u ction o f so m e c o n tr o l m e a s u re s . F o r th is rea son , su ch t im e p ie c e s m ust, a c c o r d in g to th ese S tandards, be m a rk ed in o r d e r to p e rm it the a p p ro p r ia te n ationa l au th ority take m e a s u re s fo r the in trod u ction o f a c o n tr o l sy s te m i f so d eem ed n e c e s s a r y .6 . In S e c tio n II the e x p o s u r e le v e ls f r o m e x te r n a l r a d ia t io n a re a s s e s s e d , taking in to a ccou n t the con trib u tion s fr o m gam m a ra d ia tion , beta radiation and brem sstrah lu n g, w hich a r is e fr o m the m a xim um a c t iv it ie s r e co m m e n d e d fo r o r d in a r y and s p e c ia l t im e p ie c e s .7. In Section III the m axim um ex p osu re le v e ls w hich cou ld p ossib ly a r is e f r o m the in take o f the m a x im u m p e r m is s ib le a c t iv i t ie s r e com m en d ed f o r o r d in a r y and s p e c ia l t im e p ie c e s a re a s s e s s e d . Inte r n a l ra d ia tio n ca n be c a u se d by in h a la tion o f in g e s t io n o f r a d io a c t iv e fra g m e n ts f r o m d ia ls w h ich a r e u n p ro te c te d . F o r the p u r p o se s o f s tr ic t and e ffic ie n t p ro te c tio n , one m ust assu m e that there is a p o s s ib ility that the w e a r e r o f a lu m in ou s w atch d ia l m ay inhale o r in gest som e o f the ra d io a ct iv e m atter fr o m the d ia l at lea st on ce during a life t im e .

In o r d e r to red u ce the in tern a l ir ra d ia tio n h a za rd s , the fo l lo w ing poin ts should be co n s id e re d :

(a) R a d io a ctiv e d ia ls and hands shou ld be m ade in su ch a w ay that no undue lo s s o f r a d io a c t iv ity o c c u r s f r o m th e t im e p ie c e u nder fo r e s e e a b le c o n d it io n s . F o r th is p u rp o s e , a p p ro p r ia te te s ts sh ou ld be c a r r ie d out.(b) S p e c ia l ra d io lu m in o u s t im e p ie c e s w h ich a r e out o f o r d e r and are no lo n g e r c o n s id e r e d s e r v ic e a b le should be kept under

31


c o n tro l o r d isp o se d of, s o that r is k s o f contam ination a re m ost u n likely.(c ) R a d io lu m in ou s t im e p ie c e s sh ou ld not be g iven to ch ild re n a s to y s .

8 . W ith re g a rd to s p e c ia l t im e p ie c e s , the v a lu es re co m m e n d e d in th is m anual m ay lead , in som e c a s e s , to rad ia tion d o s e s ex ce e d in g th ose set out by the IC R P fo r in d iv idu al m e m b e r s o f the popu lation , i f the use o f such t im e p ie c e s is not s t r ic t ly lim ited to the p u rp o se s fo r w hich they a re d es ign ed .

II. M AXIM UM PER M ISSIB LE A C T IV IT IE S D ERIV ED FR O M EXPO SU R E LIM ITS OF E X T E R N A L RADIATIO N

A . R adium - 226

In p ra c tice , a r isk o f ex tern a l radiation fro m ra d io iso to p e s c o n s id e r e d p e r m is s ib le f o r p ro d u c in g lu m in e s c e n c e in t im e p ie c e s a r is e s on ly in the c a se o f 226Ra. T he gonads and the b lo o d -fo rm in g o r g a n s m a y be e x p o s e d to ga m m a ra d ia tio n e m itte d b y th e r a d io a ctiv e daughter p rod u cts o f 226Ra. The skin o f the fa ce and the len s o f the e y e s co u ld be m a in ly e x p o s e d to be ta r a d ia t io n f r o m th e s e daughter p rod u cts . F in a lly , the sk in o f the w r is t cou ld be e x p osed to g a m m a ra d ia tio n p a ss in g fr o m the d ia l th rou gh the b a ck o f the w atch .

R a d iu m -2 2 6 , w h ich h as been u sed fo r about 50 y e a r s fo r p r o du cing lu m in e s ce n ce in z in c su lph ide c r y s t a ls , a c ts e s s e n t ia lly by its a lpha e m is s io n and by that o f the daughter p ro d u c ts 'w ith w hich it is m o r e o r le s s in e q u ilib r iu m w ith in the lu m in e sce n t m a te r ia l . B eta e m is s io n , is su in g fr o m the da u gh ter p ro d u c ts , p la y s o n ly a m in o r part in p rod u cin g lu m in e s ce n ce , but as it is not c o m p le te ly stopped by the g la ss p ro tectin g the dial, it p rod u ces ex tern a l ra d ia tion the in ten sity o f w hich , a fte r p a ssin g through an a v era g e 50 m g /c m 2 g la ss , can be determ ined by a co e ffic ie n t o f sp e c ific io n iza tion equal to 320 rad c m 2 /h m C i a p p rox im a te ly 14.

14 If it is assumed that all the daughter products including 210Po (RaF) are present in equilibrium amounts, when filtered by 50 m g/cm 2, the value is about 550 rad/h and, when filtered by100 m g/cm 2, the value is about 300 rad/h. A considerable fraction of the beta emission is from 21°Bi (RaE), which will only be present in appreciable amounts many years after the preparation of the radium, as it is a daughter of zl0Pb (RaD) which has a 20-yr half-life and which is likely to be eliminated in the preparation of the 226Ra from the mineral. If no 210Pb is assumed to be present, the values of beta-ray emission are about 320 and 180 rad/h for the two thicknesses respectively.

32


T A B L E V III. A N N U A L R A D IA T IO N D O S E S R E C E IV E D B Y C R IT IC A L O R G A N S

OrganType of

irradiationAnnual dose

received

Lenses of the eyes (3 mm deep)

Beta 0.11 rad a

Skin of the face Beta 0 .4 rada

Blood-forming tissues (trunk)

Gamma 0.03 radb

Skin of the wrist (at 1 .5 cm)

Gamma 4.8 radc

aValue determined experimentally.Calculated value.Calculated value. The maximum permissible dose to the skin for individualmembers of the population is 7 .5 rem/yr.

The gam m a rad ia tion o f 226Ra w hich is em itted by its daughter products is o f no im p ortan ce in the production o f lu m in escen ce ; how e v e r , it ir r a d ia te s the w h ole b od y . T he e x p o s u re r a te s ca n be ca lcu lated fo r sp e c if ic parts o f the body by using the value o f its sp e c if ic ion ization co e ffic ie n t = 9 R c m 2 /h m C i.

In te r m s o f th ese s p e c i f i c io n iza tio n c o e f f i c ie n t s , and o f the average d istan ce betw een the organ and the d ia l [1, 2, 3], it is p o s s ib le to determ ine, fo r a m axim um a ctiv ity o f 0. 15 /jC i o f 226Ra, the annual rad ia tion d o s e s r e c e iv e d by the c r i t i c a l o r g a n s ; th e se a re show n in T a b le VIII.

It can b e se e n fr o m T a b le VIII that a ll the c r i t ic a l o rg a n s r e c e iv e an annual ra d ia tio n d o s e lo w e r than that la id dow n by the IC R P .

T he " g e n e t ic " ra d ia tio n d o s e r e su lt in g fr o m e x p o s u r e o f the gon ads to gam m a ra d ia tion fr o m lu m in ou s d ia ls con ta in in g rad iu m should be d e te rm in e d fo r the popu la tion a s a w h o le . It d ep en ds on the p ro p o rt io n o f m en and w om en w e a r in g r a d io lu m in o u s w a tch e s , th eir age, ch ild expectan cy , and fin a lly , on the annual dose re ce iv e d

33


by the gonads for an activity of 0. 1 nCi from a watch worn on the w rist15.

The ICRP has suggested a maximum population genetic dose of 5 rem from all sources, in addition to medical procedures and natural background radiation. In an illustrative apportionment of this dose, the ICRP has indicated that 0. 5 rem might be allocated to the external irradiation of the population at large. This is equivalent to 17 mrem/yri6 .

B. P rom ethiu m -147

Promethium-147 is a pure beta emitter. The maximum range of its beta particles is 46 mg/ c m2 . Since the Standards set out in this manual recommend a minimum thickness of 50 m g/cm 2 for the casing of timepieces, no exposure hazard from beta radiation should exist. The total activity per timepiece (150 /JCi per ordinary timepiece) and the energy of the beta radiation ( E max = 0. 223 MeV) is low enough not to produce bremsstrahlung in such amounts and energies as would require special attention. From radiation analysis of 147pm it is known that this radioisotope is not free from contamination by other radionuclides. In particular 154Eu, a gamma-emitter, is normally present in commercially available products. However, the quantities can be kept at less than 0. 004% so that the gamma radiation can be kept at insignificant levels [_4J, and in any case lower than 0.1 mrem/h at 10-cm distance. In the case of pocket watches (ordinary timepieces) containing 147Pm, control measures should be applied in order to ensure that the dose level of 0, 1 mrem/ h at 10-cm distance is not exceeded.

C. Tritium

As tritium is a pure beta emitter with a maximum range of beta particles of 0. 6 m g /cm 2, the beta energy is low enough to ensure

15 A series of studies carried out in Switzerland showed that this specific dose was equal to 70 mR per jiCi/yr for a man and 65 mR per jiCi/yr for a woman.

16 It emerged from a statistical study carried out in Switzerland that about 66% of the male and 25% of the female population wear watches with dials excited by an average activity of 0.1 jiCi of radium and taking into account the age and the fertility rate, this works out at a genetic dose of 100 mR per generation, i.e . 3.3 mR/yr. Owing to the high percentage of luminous timepieces in use in Switzerland, these values can be considered as exceptionally high and will be lower in other countries.

34


that no external radiation results from luminous watches containing tritium. The outer layer of the skin has a thickness of about 0. 07 mm, which is equivalent to a range of 7 mg/ cm2.

III. MAXIMUM PERMISSIBLE ACTIVITIES DERIVED FROMEXPOSURE LIMITS OF INTERNAL RADIATION

After introduction into the body, tritium, promethium-147 and radium- 226, depending on their chemical state, i . e. soluble or insoluble, follow the general metabolic channels, each lodging in one or several critical organs. Once lodged, the ionizing effect diminishes according to the effective half-life (i.e. physical half-life and biological half-life). The radiation dose received by the critical organ must remain below the maximum permissible doses specified in the basic Radiation Protection Norms. In estimating this dose, the chemical form of the radioactive substance — in particular as regards radium-226 (depending on whether it is present in the form of a soluble or insoluble salt) — has to be taken into consideration. It will always be desirable that the radioisotopes should be present in as insoluble a form as possible.

According to the Report of the ICRP Committee II with regard to soluble material, tritium settles, after ingestion or inhalation, throughout the whole body. Promethium-147 settles, through inhalation, in the bones, the amount absorbed by ingestion being negligible. Radium-226, after ingestion, lodges mainly in the bones. Radioluminous paints may be relatively insoluble and the critical organ may therefore be the gastrointestinal (GI) tract, the lung or others.

The only possible risk involved is of ingestion or inhalation of a fragment of luminescent material, or of intake through wounds, if the watch is opened or the protective glass is broken. This possible hazard is assessed in Table IX, which gives the radiation dose in rems received by the critical organs, assuming an accidental ingestion or inhalation of radioactivity equal to one-tenth of that of a watch containing the average perm issible quantity17. The doses indicated in Table II are dissipated in less than twelve months in the case of tritium, over several years for promethium-147 (corresponding to the total disintegration of the isotope), and within

17 The figures on which the calculations are based were taken from the Report of ICRP Com-mittee II on Permissible Dose for Internal Radiation (1959).

35


TABLE IX. DOSE EQUIVALENT VALUES CORRESPONDING TO VARIOUS MODES OF INTAKE OF ONE-TENTH OF THE AVERAGE PERMISSIBLE ACTIVITY RECOMMENDED FOR ORDINARY WATCHES

Radionuclide Chemicalform

Mode of intake

Criticalorgan

Activity ingested

(M Ci)

Dose equivalent (rems)

(Insol.) Ingestion GI 500 6 .5 X 1 0 '1Inhalation Lung 500 5 .0

Ingestion Body tissue 500 1 .0 5 X 1 0 '1

(S o l.) InhalationThrough

wounds

Body tissue Body tissue

500500

1 .0 5 X 1 0 '11 .0 5 X 1 0 _1

(Insol. ) Ingestion GI 10 8 .8 X 1 0 " 2Inhalation Lung 10 7 .0 X 1 0 '1

Pm Ingestion Bone 10 7 .4 X 10 -*

(Sol. ) InhalationThrough

wounds

BoneBone

1010

2 .07 .4

(Insol.) Ingestion GI 0 .0 1 7 .6 X 1 0 ‘ 3

Inhalation Lung 0 .0 1 1 .3

226 Ra Ingestion Bone 0 .0 1 3 .1

(S o l.) Inhalation Bone 0 .0 1 3 .1Through

woundsBone 0 .0 1 1 0 .4

50 years for radium-226 (following the basic ICRP concept taking 50 years in relation to the life span).

The annual doses are still below the maximum permissible dose of 0. 5 rem applicable to the whole body, the gonads and the blood- forming organs. By and large, accidental absorption by an individual of a fragment of dial or hand containing the activities indicated represents a negligible hazard, and is an acceptable risk with regard to the population as a whole.

36


Similar considerations may be applied to ordinary clocks and special timepieces, with correspondingly greater doses because of the larger activities permitted. In all these considerations it should be borne in mind that such accidental absorption will be exceedingly rare.

REFERENCES TO ANNEX II

[ 1] JOYET, G., Helvetica Physica Acta, XXXIII, 6/7 (I960) 557.[2] SEELENTAG, W ., KLOTZ, E., Strahlentherapie 110 (1959) 606.[3 ] JOYET, G., MILLER, M ., Experientia, XVI/8 (1960) 342.[4] VEIT, W., Untersuchungen iiber mit Promethium aktivierte Leuchtfarben, Kerntechnik 5

(1963) 223-24.

37


I A E A S A L E S A G E N T S

Orders for Agency publications can be p laced with your book se ller or any o f our sa les agents lis ted below :

A R G E N T I N AC om ision N acional de Energia A tom ica A venida del L ibertador General San Martin 8250 Buenos A ires - Sue. 29

A U S T R A L I AHunter Publications*23 M cK illop Street Melbourne* C .l

A U S T R I AGeorg Fromme & C o.Spengergasse 39 A -1050, V ienna V

B E L G I U MO ffice international de librairie 30* avenue Mamix B ru ssels 5

B R A Z I LLivraria K osm os Editora Rua do R osa rio , 135-137R io de Janeiro

A gen cia Expoente O scar M. Silva Rua Xavier de T o le d o . 1 4 0 »1 ° Andar (C aixa P osta l N o. 5.614)Sao Paulo

BYELORUSSIAN SO VIET SOCIALISTREPU BLIC

See under USSR

CANADAThe Queen*s Printer Ottawa* Ontario

C H I N A (Taiw an)Books and S c ien tific Supplies Service* Ltd.*P .O . Box 83 T a ipei

CZECHO SLO VAK SOCIALIST REPU BLIC S .N .T .L .Spolena 51 N ove Mesto Prague 1

D E N M A R KEjnar Munksgaard Ltd.6 N oiregade Copenhagen K

F I N L A N DAkateeminen Kirjakauppa Keskuskatu 2 H elsinki

F R A N C EO ffice international de docum entation e t librairie 48* rue G ay-L ussac F -75 , Paris 5 e

G E R M A N Y , Federal R epublic of R. Oldenbourg Rosenheim er Strasse 145 8 Munich 8

H U N G A R Y KulturaHungarian Trading C o. for Books and N ewspapers P .O .B . 149 Budapest 62

I S R A E LH eiliger and C o.3 Nathan Strauss Street Jerusalem

I T A L YA genzia Editoriale Intem azionale O rgan izzazion i U niversali (A .E .I.O .U .) Via M eravigli 16 Milan

J A P A NMaruzen Company Ltd .6* Tori Nichome N ihonbashi (P .O . Box 605)Tok yo Central

M E X I C OL ibrena Internacional A v . Sonora 206 M exico 11* D .F .

N E T H E R L A N D SN .V . Martinus N ijhoff Lange Voorhout 9 The Hague

N E W Z E A L A N DWhitcombe & Tom bs* Ltd.G .P .O . Box 1894 Wellington* C .l


N O R W A YJohan Grundt Tanum Karl Johans gate 43O slo

P A K I S T A NKarachi Education Society Haroon Chambers South N apier Road (P .O . Box N o. 4866)Karachi 2

P O L A N DOsrodek R ozpow szechniana Wydawnictw Naukowych P olsk a Akademia Nauk Pal'ac Kultury i Nauki Warsaw

R O M A N I ACartimexRue A. Briand 14»18 Bucarest

SOUTH A FRICAVan S ch aik 's Bookstore (P ty) Ltd. Libf* Building Church Street (P .O . Box 724)Pretoria

S P A I NLibreria BoschRonda de la U niversidad 11Barcelona

S W E D E NC .E . Fritzes Kungl. H ovbokhandel Fredsgatan 2 Stockholm 16

S W I T Z E R L A N D Librairie Payot Rue Grenus 6 1211 Geneva 11

T U R K E YLibrairie H achette 469, Istik la l Caddesi B eyoglu , Istanbul

UKRAINIAN SOVIET SO CIA1ISTREPU BLIC

See under USSR

UNION OF SOVIET SOCIALISTREPU BLICS

Mezhdunarodnaya Kniga Smolenskaya-Sennaya 32*34 M oscow G-200

UNITED KINGDOM OF G R E A TBRITAIN AND NORTHERN IRE LAN D

Her M ajesty ’ s Stationery O ffice P .O . Box 569 London, S .E .l

UNITED STATE S O F AMERICA N ational Agency for International P u b lica tion s . Inc. 317 E ast 34th Street New York, N .Y . 10016

V E N E Z U E L ASr. Braulio G abriel Chacares Gobernador a Candilito 37 Santa R osa lia (Apartado P osta l 8092)Caracas D .F .

Y U G O S L A V I AJugoalovenaka K ajiga T erazije 27 Belgrade

IAEA pub lications can a lso be purchased retail at the United Nations B ookshop at United Nations Headquarters, New York, at the new s-stand at the A g en cy ’ s Head* quarter^, Vienna, and at most con feren ces , sym posia and seminars organized by the A gen cy .

In order to fa cilita te the distribution of its p u b lica tion s, the Agency is prepared to a ccep t payment in UNESCO coupons or in lo ca l cu rren cies.

Orders and inquiries from countries where sa les agents have not yet been appointed may be sent to :

D istribution and S ales Group, International Atom ic Energy A gency,Kam tner R ing 11* A -1010, Vienna I , Austria


INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA. 1967

PRICE: US $1.00Austrian Schillings 26.- ( 7 2 stg: F.Fr. 4,90; DM 4,-)


Radiation Protection Standards for Radioluminous Timepieces

Documents

Transcript of Radiation Protection Standards for Radioluminous Timepieces