SIST EN ISO 20553:2017

SLOVENSKI STANDARD
01-december-2017
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Radiation protection - Monitoring of workers occupationally exposed to a risk of internal
contamination with radioactive material (ISO 20553:2006)
Radioprotection - Surveillance professionnelle des travailleurs exposés à un risque de
contamination interne par des matériaux radioactifs (ISO 20553:2006)
Ta slovenski standard je istoveten z: EN ISO 20553:2017
ICS:
13.100 Varnost pri delu. Industrijska Occupational safety.
higiena Industrial hygiene
13.280 Varstvo pred sevanjem Radiation protection
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 20553
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2017
EUROPÄISCHE NORM
ICS 13.280
English Version
Radiation protection - Monitoring of workers
occupationally exposed to a risk of internal contamination
with radioactive material (ISO 20553:2006)
Radioprotection - Surveillance professionnelle des
travailleurs exposés à un risque de contamination
interne par des matériaux radioactifs (ISO
20553:2006)
This European Standard was approved by CEN on 13 September 2017.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20553:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 20553:2006 has been prepared by Technical Committee ISO/TC 85 “Nuclear energy,
nuclear technologies, and radiological protection” of the International Organization for Standardization
(ISO) and has been taken over as EN ISO 20553:2017 by Technical Committee CEN/TC 430 “Nuclear
energy, nuclear technologies, and radiological protection” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2018, and conflicting national standards shall be
withdrawn at the latest by April 2018.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 20553:2006 has been approved by CEN as EN ISO 20553:2017 without any modification.

INTERNATIONAL ISO
STANDARD 20553
First edition
2006-04-15
Radiation protection — Monitoring of
workers occupationally exposed to a risk
of internal contamination with radioactive
material
Radioprotection — Surveillance professionnelle des travailleurs
exposés à un risque de contamination interne par des matériaux
radioactifs
Reference number
ISO 20553:2006(E)
©
ISO 2006
ISO 20553:2006(E)
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ii © ISO 2006 – All rights reserved

ISO 20553:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions. 2
3.1 Absorption types . 2
4 Symbols and abbreviated terms . 6
5 Purpose and need for monitoring programmes . 6
6 Reference levels. 8
7 Routine monitoring programmes. 9
7.1 General aspects . 9
7.2 Workplace monitoring. 10
7.3 Individual monitoring . 10
7.4 Methods and time intervals . 11
8 Special monitoring programmes. 14
8.1 General aspects . 14
8.2 Workplace monitoring. 14
8.3 Individual monitoring . 15
9 Task-related monitoring programmes.17
9.1 General aspects . 17
9.2 Workplace monitoring. 17
9.3 Individual monitoring . 17
10 Special cases of individual monitoring . 18
10.1 Actinides. 18
10.2 Contamination in wounds. 18
10.3 Contamination on the skin. 18
11 Recording, documentation and reporting. 18
11.1 Recording and documentation. 18
11.2 Reporting . 20
12 Quality management. 20
Bibliography . 22

ISO 20553:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 20553 was prepared by Technical Committee ISO/TC 85, Nuclear energy, Subcommittee SC 2, Radiation
protection.
iv © ISO 2006 – All rights reserved

ISO 20553:2006(E)
Introduction
In the course of employment, individuals might work with radioactive materials that, under certain
circumstances, could be taken into the body. Protecting workers against risks of incorporated radionuclides
requires the monitoring of potential intakes and/or the quantification of actual intakes and exposures. The
selection of measures and programmes for this purpose requires decisions concerning methods, techniques,
frequencies etc. for measurements and dose assessment. The criteria permitting the evaluation of the
necessity of such a monitoring programme or for the selection of methods and frequencies of monitoring
usually depend upon the legislation, the purpose of the radiation protection programme, the probabilities of
potential radionuclide intakes, and the characteristics of the materials handled.
This International Standard offers guidance for the decision whether a monitoring programme is required and
how it should be designed. Its intention is to optimise the efforts for such a monitoring programme consistent
with legal requirements and with the purpose of the radiation protection programme. Recommendations of
international expert bodies and international experience with the practical application of these
recommendations in radiation protection programmes have been considered in the development of this
International Standard. Its application facilitates the exchanges of information between authorities, supervisory
institutions and employers. The International Standard is not a substitute for legal requirements.
In the International Standard, the word “shall” is used to denote a requirement and no deviation is allowed.
The word “should” is used to denote a recommendation from which justified deviations are allowed. The word
“may” is used to denote permission.
INTERNATIONAL STANDARD ISO 20553:2006(E)

Radiation protection — Monitoring of workers occupationally
exposed to a risk of internal contamination with radioactive
material
1 Scope
This International Standard specifies the minimum requirements for the design of professional programmes to
monitor workers exposed to the risk of internal contamination by radioactive substances and establishes
principles for the development of compatible goals and requirements for monitoring programmes.
This International Standard addresses the
a) purposes of monitoring and of monitoring programmes;
b) description of the different categories of monitoring programmes;
c) quantitative criteria for conducting monitoring programmes;
d) suitable methods for monitoring and criteria for their selection;
e) information that has to be collected for the design of a monitoring programme;
f) general requirements for monitoring programmes (e.g. detection limits, tolerated uncertainties);
g) frequencies of measurements;
h) special cases;
i) quality assurance; and
j) documentation, reporting, record-keeping.
This International Standard does not address
⎯ the monitoring of exposure to radon and its radioactive decay products;
⎯ detailed descriptions of measuring methods and techniques;
⎯ detailed procedures for in vivo measurements and in vitro analyses;
⎯ interpretation of monitoring results in terms of doses;
⎯ biokinetic data and mathematical models for converting measured activities into absorbed dose,
equivalent dose and effective dose; or
⎯ the investigation of the causes or implications of an exposure or intake.
ISO 20553:2006(E)
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 5725-1:1994, Accuracy (trueness and precision) of measurement methods and results — Part 1: General
principles and definitions
ISO 12790-1:2001, Radiation protection — Performance criteria for radiobioassay — Part 1: General
principles
BIPM/IEC/IFCC/ISO/IUPAC/IUPAP/OIML, International vocabulary of basic and general terms in metrology
(VIM), 1993
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5725-1, ISO 12790-1 and
International vocabulary of basic and general terms in metrology (VIM) and the following apply.
3.1 Absorption types
3.1.1
type F
F
deposited materials that have high (fast) rates of absorption into body fluids from the respiratory tract
3.1.2
type M
M
deposited materials that have intermediate (moderate) rates of absorption into body fluids from the respiratory
tract
3.1.1
type S
S
deposited materials that have low (slow) rates of absorption into body fluids from the respiratory tract
3.2
accuracy of measurement
characteristics of an analysis or determination that ensure that both the bias and precision of the resulting
quantity remains within specified limits
3.3
activity
transition rate
NOTE The activity is stated in becquerels (Bq).
3.4
activity median aerodynamic diameter
AMAD
value of aerodynamic diameter such that 50 % of the airborne activity in a specified aerosol is associated with
particles smaller than the AMAD, and 50 % of the activity is associated with particles larger than the AMAD
NOTE The aerodynamic diameter of an airborne particle is the diameter that a sphere of unit density would need to
have in order to have the same terminal velocity when settling in air as the particle of interest.
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ISO 20553:2006(E)
3.5
clearance
net effect of the biological processes by which radionuclides are removed from the body or from a tissue,
organ or region of the body
NOTE The clearance rate is the rate at which this occurs.
3.6
contamination
activity of radionuclides present on surfaces, or within solids, liquids or gases (including the human body),
where the presence of such radioactive material is unintended or undesirable
3.7
dose
[ICRU Report 60:1998]
3.7.1
annual dose
committed effective dose resulting from all intakes occurring during a calendar year
3.7.2
committed effective dose
time integral of the equivalent-dose rate over an integration period
NOTE In this International Standard, the integration time is 50 years following any intake.
3.7.3
effective dose
sum of the weighted equivalent doses in all tissues and organs of the body
NOTE The effective dose is expressed in units of joules per kilogram (special name: sievert, Sv).
3.7.4
total dose
sum of effective dose from external radiation and committed effective dose from internal radiation
3.8
excretion function
the fraction of an intake excreted per day after a given time has elapsed since the intake occurred
3.9
event
any unintended occurrence, including operating error, equipment failure or other mishap, the consequences or
potential consequences of which are not negligible from the point of view of protection or safety
3.10
intake
activity of a radionuclide taken into the body in a given time period or as a result of a given event
3.11
in vitro analysis
analysis including measurements of radioactivity present in biological samples taken from an individual
NOTE 1 These include urine, faeces and nasal samples. In special monitoring programmes, samples of other materials
such as blood and hair may be taken.
NOTE 2 These analyses are sometimes referred to as indirect measurements.
ISO 20553:2006(E)
3.12
in vivo measurement
measurement of radioactivity present in the human body, carried out using detectors to measure the radiation
emitted
NOTE 1 Normally the measurement devices are whole-body counters or part-body (e.g. lung, thyroid) counters.
NOTE 2 Sometimes also referred to as direct measurements.
3.13
investigation level
level of dose, exposure or intake (specified by the employer or the regulatory authority) at or above which an
investigation is conducted
NOTE 1 See Clause 6.
3.14
detection limit
DL
smallest actual amount of a measurand that can be detected by a measuring method
NOTE Adapted from ISO 11929-7:2005.
3.15
monitoring
measurement of dose or contamination for the purpose of the assessment or control of exposure to radiation
or radioactive material, and the interpretation of the results
3.15.1 Categories of monitoring programme
NOTE The present International Standard distinguishes four different categories of monitoring programme, namely
routine monitoring programmes (3.15.1.1), special monitoring programmes (3.15.1.2), confirmatory monitoring
programmes (3.15.1.3), and task-related monitoring programmes (3.15.1.4).
3.15.1.1
routine monitoring programme
systematic monitoring programme
monitoring programme associated with continuing operations and intended to demonstrate that working
conditions, including the levels of individual dose, remain satisfactory, and to meet regulatory requirements
3.15.1.2
special monitoring programme
monitoring programme performed to quantify significant exposures following actual or suspected abnormal
events
3.15.1.3
confirmatory monitoring programme
monitoring programme carried out to confirm assumptions about working conditions, for example that
significant intakes have not occurred
3.15.1.4
task-related monitoring programme
specific monitoring programme
monitoring programme related to a specific operation, to provide information on a specific operation of limited
duration, or following major modifications applied to the installations or operating procedures, or to confirm
that the routine monitoring programme is suitable
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ISO 20553:2006(E)
3.15.2 Types of monitoring
NOTE This International Standard distinguishes two different types of monitoring in each category of monitoring,
individual monitoring (3.15.2.2) and workplace monitoring (3.15.2.3). A further type of monitoring, collective
monitoring (3.15.2.1), is regarded as a particular form of workplace monitoring.
3.15.2.1
collective monitoring
monitoring applied to representative members of a group of workers whose working conditions are not
significantly different in terms of the risk of intakes
3.15.2.2
individual monitoring
monitoring by means of equipment worn by individual workers, or measurement of the quantities of radioactive
materials in or on the bodies of individual workers, or measurement of radioactive material excreted by
individual workers
3.15.2.3
workplace monitoring
monitoring using measurements made in the working environment
3.16
monitoring interval
period between two times of measurement
3.17
quality assurance
QA
planned and systematic actions necessary to provide adequate confidence that a process, measurement or
service will satisfy given requirements for quality, for example, those specified in a licence
3.18
quality control
QC
part of quality assurance intended to verify that systems and components correspond to predetermined
requirements
3.19
quality management
QM
all activities of the overall management function that determine the quality policy, objectives and
responsibilities, and implement them by means such as quality planning, quality control, quality assurance and
quality improvement within the quality system
3.20
recording level
level of dose, exposure or intake (specified by the employer or the regulatory authority) at or above which
values of dose, exposure or intake received by workers are to be entered in their individual exposure records
NOTE See Clause 6 for the reference levels.
3.21
reference level
investigation level or recording level
3.22
retention function
fraction of an intake present in the body or in a tissue, organ or region of the body after a given time has
elapsed since the intake occurred
ISO 20553:2006(E)
3.23
time of measurement
in the case of in vitro analysis, the time at which the biological sample (e.g. urine, faeces) was taken from the
individual concerned. In the case of in vivo measurements, the time at which the in vivo measurement begins.
4 Symbols and abbreviated terms
AMAD Activity median aerodynamic diameter
A Mathematical symbol for the detection limit, used in equations
DL
DL Detection limit
e(50) Dose coefficient: committed effective dose accumulated within 50 years following a unit intake
E(t) Value of the excretion function at time, t, (in days) after a unit intake
f Gastro-intestinal uptake fraction
IAEA International Atomic Energy Agency
ICRP International Commission on Radiological Protection
QA Quality assurance
QC Quality control
QM Quality management
R(t) Value of the retention function at time, t, (in days) after a unit intake
RPE Respiratory protective equipment
∆T Time interval (in days) between two measurements in a routine monitoring programme
5 Purpose and need for monitoring programmes
The purpose of monitoring, in general, is to verify and document that the worker is protected adequately
against risks from radionuclide intakes and the protection complies with legal requirements. Therefore, it forms
part of the overall radiation protection programme, which starts with an assessment to identify work situations
in which there is a risk of radionuclide intake by workers, and to quantify the likely intake of radioactive
material and the resulting committed effective dose received. Decisions about the need for monitoring and the
design of the monitoring programme should be made in the light of such a risk assessment.
Routine monitoring programmes are performed to quantify exposures where there is the possibility either of
undetected accidental intakes or of chronic intakes. The basis for routine monitoring programmes is the
assumption that working conditions, and thus risks of intake, remain reasonably constant. The design of such
a programme of regular measurements strongly depends on the level of the annual dose the quantification of
which is ensured. This level should be well below legally relevant limits; its definition should take into account
uncertainties, for example in activity measurement and dose assessment. If this level is too high, intakes
representing considerable fractions of dose limits could be overlooked, whilst a low value can cause the
expenditure of unnecessary efforts at low exposures.
Special monitoring programmes are performed to quantify significant exposures following actual or suspected
abnormal events. Therefore, in comparison to routine monitoring programmes, the time of intake is usually
much better known and additional information can be available, which helps to reduce the uncertainty of
6 © ISO 2006 – All rights reserved

ISO 20553:2006(E)
assessment. The purposes of dose assessment in such cases include assisting in decisions about
countermeasures (e.g. decorporation therapy), compliance with legal regulations and aiding decisions for the
improvement of conditions at the workplace. In most cases, special monitoring programmes are performed
individually. In cases where there is reason to suspect that exposure limits could be exceeded, it can be
appropriate to extend the measurements in order to derive individual retention and excretion functions and
biokinetic model parameters.
Confirmatory monitoring programmes can be required to check the assumptions about exposure conditions
underlying the procedures selected, e.g. the effectiveness of protection measures. It may consist of workplace
or individual monitoring, e.g. as occasional measurements to investigate the potential accumulation of activity
in the body.
Task-related monitoring programmes apply to a specific operation. The purpose and the dose criteria for
carrying out task-related monitoring programmes are identical to those for routine monitoring programmes.
Individual monitoring gives information needed to assess the exposure of a single worker by measuring
individual body activities, excretion rates or activity inhaled (using personal air samplers).
Workplace monitoring, which includes collective monitoring, provides exposure assessments for a group of
workers assuming identical working conditions i.e. risks of intake as well as all factors influencing the resulting
doses. It is mainly used in cases where individual monitoring is not appropriate and it can also be needed in
those cases where individual monitoring is not sufficiently sensitive. In some cases, results of workplace
monitoring are needed to support individual dose assessments (e.g. air monitoring can provide information on
the time of an intake).
Factors determining the need for a monitoring programme are
⎯ the magnitude of likely exposures;
⎯ the need to recognise incorporation events should they occur;
⎯ the need to assess the effectiveness of protective equipment (RPE).
Table 1 gives criteria defining the need for a monitoring programme, and this is illustrated diagrammatically in
Figure 1.
The numbers given in this International Standard take into account only exposures by incorporated
radionuclides. In cases where external exposure is likely to exceed the internal exposure, the values of
Table 1 and Figure 1 are to be reduced by a factor of two.
Accordingly, it is necessary to assess the likely magnitude of exposures without taking into account personal
protective measures. If available, this assessment can be done on the basis of results of earlier monitoring
programmes (individual or workplace monitoring). If no other reliable information is available or can be
obtained, the likely annual dose may be estimated according to the criteria suggested by IAEA Safety Reports
[3]
Series No. 18 or on the basis of national guidelines.
Table 1 — Need for monitoring programmes according to the exposure situation
Type of monitoring required Normative Recommended level
Workplace monitoring If the worker is occupationally exposed If the likely annual committed effective
and the assessed dose contribution dose exceeds 1 mSv
from intakes of radionuclides is likely to
be significant
Individual monitoring If the worker can be exposed to more If the likely annual total dose exceeds
than 30 % of the dose limit by internal 6 mSv
exposure
ISO 20553:2006(E)
Figure 1 — Illustration of the need for monitoring programmes according to the exposure situation
If a worker is exposed to more than one radionuclide, the design of a monitoring programme may disregard
radionuclides the sum of whose contributions in increasing order is likely to be less than 1 mSv per year.
In the case of mixtures where the radionuclide composition is well known, it is possible to use the
measurement of a single radionuclide to infer the activities of the others. This approach is acceptable if the
additional uncertainty (in terms of dose) arising from the incomplete knowledge of the radionuclide
composition does not exceed 10 %.
6 Reference levels
Reference levels are the values of quantities above which a particular action or decision shall be taken. The
purpose of setting these levels is so that unnecessary, non-productive work can be avoided and resources
can be used where they are most needed. Reference levels include the recording level, above which a dose
assessment has to be recorded, lower values being ignored; and the investigation level, above which the
exposure estimates have to be confirmed by additional investigations (see Table 2).
NOTE The scope of this International Standard does not include the investigation of the causes or implications of an
exposure or intake.
The recording level shall be set at a value corresponding (having regard to the length of the monitoring
interval) to an annual dose no higher than 5 % of the annual dose limit. The investigation level shall be set at a
value corresponding to an annual dose no higher than 30 % of the annual dose limit.
8 © ISO 2006 – All rights reserved

ISO 20553:2006(E)
Table 2 — Reference levels for monitoring internal exposures
Level Meaning
Recording level The recording level is the level of dose, exposure or intake at or above which
dose assessments have to be recorded in the individual exposure records. It
shall be set at a value corresponding to an annual dose no higher than 5 %
of the annual dose limit. Results falling below this level may be shown as
“below recording level”.
Investigation level The investigation level is the level of dose, exposure or intake at or above
which investigation has to be made in order to reduce the uncertainty
associated with the dose assessment. The level shall be set at a value
corresponding to an annual dose no higher than 30 % of the annual dose
limit.
7 Routine monitoring programmes
7.1 General aspects
Routine monitoring programmes are established to quantify exposures where there is the possibility either of
undetected accidental intakes or of chronic intakes. Measurements in a routine monitoring programme are
made at pre-determined times and are not related to any known intake events. Decisions therefore have to be
made in advance concerning methods, frequencies, and the underlying biokinetic models. For the evaluation
of measured values in terms of intakes it also is necessary to make assumptions concerning the time interval
between intake and measurement.
Routine monitoring programmes shall be established including suitable workplace monitoring and individual
monitoring according to the criteria in Table 1, taking into account the requirements of this clause.
The following general requirements shall be observed when specifying a routine monitoring programme:
⎯ the consequences resulting from an unknown time interval between intake and measurement shall be
limited so that
⎯ on average over many monitoring intervals, doses are not underestimated, and
⎯ the maximum underestimate of the dose resulting from a single intake does not exceed a factor of
three, and
⎯ the detection of all annual exposures that can exceed 1 mSv shall be ensured;
NOTE For some radionuclides, this requirement can only be achieved by workplace monitoring.
⎯ at least two measurements shall be performed annually.
The maximum overestimation is in nearly all cases greater than the maximum underestimation. The constraint
on the maximum underestimation of a single intake does not exclude a considerable overestimation.
These requirements together with the assumptions about the pattern of intake and the sensitivity of the
selected methods of measurement determine the frequency of the routine measurements.
The objectives of a monitoring programme and the way it is to be organized shall be documented according to
Clause 11 including the basis for interpreting the results. The monitoring programme shall be reviewed by
means of a confirmatory monitoring programme after any major modifications have been made to the
installation, to operations, or to the regulatory requirements.
ISO 20553:2006(E)
7.2 Workplace monitoring
Workplace monitoring includes collective monitoring (i.e. individual monitoring of selected workers
representing groups of workers), and measurements of airborne activity and surface contamination in the
workplace. Surface contamination is not directly related to individual exposure but can indicate increased risk
of intake.
Continuous monitoring of airborne radioactive material is important, because inhalation is generally the main
exposure pathway for workers. The main objectives of monitoring airborne activity are
⎯ to help to assess the internal exposure of workers through inhalation;
⎯ to rapidly detect abnormal or deteriorating conditions, thereby making it possible to take the appropriate
protective action, for example, the use of respiratory protective equipment;
⎯ to provide information for setting up individual monitoring programmes for workers.
The establishment of an air-monitoring system in order to detect and assess collective or individual exposure
requires knowledge of the conditions at the workplace and the materials handled there. The design of the
system is expected to be tailored to the risk of intake.
The results of air-monitoring can be used to estimate the intake of a radioactive substance by workers but
reliance on measurement of airborne activities alone can lead to errors in exposure estimates. This is true
when sources of air contamination are localized or change position over time, often because of worker action
or movement.
Workplace air-monitoring results can be considered as representative provided they meet two criteria. Firstly,
they reliably shall not underestimate the intakes as measured in vivo or by in vitro individual measurements.
Secondly, they shall be confirmed by a confirmatory monitoring programme, involving the use of individual
air-sampling devices or the use of individual excretion measurements.
NOTE The requirement to avoid underestimation may be achieved by applying correction factors taking into account
spatial and temporal variability of radionuclide concentrations in the worker’s breathing zone.
7.3 Individual monitoring
Individual monitoring of radionuclides can be made by in vivo measurements or in vitro analyses, by taking
continuous air samples using individual air-sampling devices or by a combination of all these methods. The
selection depends on a number of factors, such as the following:
⎯ radiation emitted by the radionuclide and its progeny;
⎯ decay rate of the radionuclide;
⎯ retention in the body or the excretion rate from the body of the contaminant as a function of the time
between intake and measurement;
⎯ biokinetics, organ deposition and excretion pathway of the contaminant;
⎯ technical feasibility of measurement.
The measurement frequency required for a routine monitoring programme depends on the retention and
excretion of the radionuclide, the sensitivity of the available measurement techniques and the uncertainty that
is acceptable when estimating annual intake and committed effective dose, as given in Equations (1) and (2):
For in vivo measurements:
A 365
DL
e(50)⋅⋅ u 1mSv (1)
RT∆∆T
()
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ISO 20553:2006(E)
For in vitro analyses:
A 365
DL
e(50)⋅⋅ u 1mSv (2)
ET∆∆T
()
If exposure to more than one radionuclide cannot be ruled out, this requirement shall be adjusted accordingly
so that a total annual dose of 1 mSv can reliably be detected and assessed. Small contributions may be
ignored; see Clause 5.
The maximum potential underestimation shall not exceed a factor of three; assuming that a single intake
occurred in the middle of the monitoring interval this requirement means, as given in Equations (3) and (4):
For in vivo measurements:
∆T
R()
u 3 (3)
RT()∆
For in vitro analyses:
∆T
E()
u 3 (4)
ET()∆
Individual air-sampling devices worn by workers can give an adequate estimate of the intake of each worker.
However, they are susceptible to uncertainty resulting from the sampling of a single, non-representative
particle. The interpretation of results can require a confirmatory monitoring programme to determine the
distribution of particle sizes in aerosols. The presence of a few isolated high results from an individual
air-sampling device indicates the need for a special monitoring programme.
Excretion analysis usually requires a 24 h sample collected in a manner that avoids external contamination.
For certain elements, for which equilibrium is quickly reached between the blood and the urinary
concentrations, it is also possible to take samples over shorter periods (“spot samples”) normalizing to 24 hour
excretion on the basis of the creatinine concentration. Faecal excretion analysis is strongly recommended to
be performed over three consecutive days.
In the case of material with very short effective half-lives (i.e. < 0,5 d), routine individual monitoring is in most
cases not necessary, as the effective dose is dominated by the external exposure. However, there should be
a considerable degree of confidence in the workplace monitoring system.
The measurement of nasal sample activity is another way to detect the inhalation of α-emitting particles; a
positive result from such a measurement can be used as an indicator for further individual investigations for all
the workers in the group. Such a measurement can also be useful for reducing the uncertainty in the time of
an intake for dose assessment.
7.4 Methods and time intervals
The methods and time intervals summarized in this subclause were derived from the principles laid down
above and the following assumptions:
[11]
⎯ ICRP 66 models for inhalation (default values for workers: AMAD = 5 µm);
[12]
⎯ element-specific retention and clearance functions defined by ICRP 78 ;
⎯ acute intake by inhalation at the mid-point of the monitoring interval. This is a reasonable assumption for
chronic intakes and, on average, it prevents the underestimation of intakes;
⎯ with DL values of routine measurements as from ICRP 78.
ISO 20553:2006(E)
The methods and time intervals for routine monitoring programmes are summarized in Table 3 for commonly
used radionuclides. Other methods and time intervals may be used, if they fulfil the requirements defined
above (see 7.1) and the above assumptions are shown not to be appropriate for particular cases. For other
radionuclides, the methods and the time intervals of measurements shall be selected observing the
requirements laid down above (see 7.1).
Table 3 — Methods and maximum time intervals for routine monitoring programmes
In vitro analyses In vivo measurements
Radionuclide Absorption type
Urine Whole body Thyroid
days days days
H HTO 30 — —
C Organic 7 — —
Dioxide 180 — —
P F 30 — —
P F 30 — —
S F 7 — —
Cl F 30 — —
Cr F (15) 15 —
Mn M — 90 —
Fe M — 90 —
Co S (30) 180 —
Co S (90) 180 —
Co S (180) 180 —
Ni M 15 — —
Se M — 180 —
Sr F, S 30 — —
Sr F, S F:30, S:180 — —
110m
Ag S — 180 —
I F (90) — 90
I F (15) — 15
Cs F (180) 180 —
Ra M 180 — —
NOTE Where a figure is given in brackets, this is an alternative to the value in a diff
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