prEN ISO 27048

Radiation protection - Dose assessment for the monitoring of workers for internal radiation exposure (ISO 27048:2011)

ISO 27048:2011 specifies the minimum requirements for the evaluation of data from the monitoring of workers occupationally exposed to the risk of internal contamination by radioactive substances. It presents procedures and assumptions for the standardised interpretation of monitoring data, in order to achieve acceptable levels of reliability. Those procedures allow the quantification of exposures for the documentation of compliance with regulations and radiation protection programmes. Limits are set for the applicability of the procedures in respect of the dose levels above which more sophisticated methods will have to be applied.
ISO 27048:2011 addresses the following: procedures for dose assessment based on reference levels for routine and special monitoring programmes; assumptions for the selection of dose-critical parameter values; criteria for determining the significance of monitoring results; interpretation of workplace monitoring results; uncertainties arising from sampling, measurement techniques and working conditions; the special topics of interpretation of multiple data arising from different measurement methods at different times, handling data below the decision threshold, rogue data, and calculation of doses to the embryo/foetus and infant; reporting/documentation; quality assurance.
It is not applicable to the following: dosimetry for litigation cases; modelling for the improvement of internal dosimetry; the potential influence of decorporation measures (e.g. administration of chelating agents); the investigation of the causes or implications of an exposure; dosimetry for contaminated wounds.

Strahlenschutz - Dosisermittlung für die Überwachung der inneren Strahlungsbelastung von beruflich strahlenexponierten Personen (ISO 27048:2011)

Radioprotection - Estimation de la dose interne dans le cadre de la surveillance des travailleurs en cas d'exposition aux rayonnements (ISO 27048:2011)

L'ISO 27048:2011 spécifie les exigences minimales de l'évaluation des données de la surveillance professionnelle des travailleurs exposés vis-à-vis du risque de contamination interne par des composés radioactifs. Elle présente des procédures et des hypothèses utiles à l'interprétation normalisée des données de surveillance afin d'obtenir des niveaux acceptables de fiabilité. Ces procédures permettent la quantification des expositions afin de documenter la conformité aux exigences réglementaires et aux programmes de radioprotection. L'ISO 27048:2010 établit des limites d'application de ces procédures en termes de niveaux de dose au-dessus desquelles des méthodes plus sophistiquées seront appliquées.
L'ISO 27048:2011 aborde les éléments suivants: les procédures d'estimation de dose interne fondées sur les niveaux de référence utilisés dans les programmes de surveillance de routine et postincidentelle; les hypothèses pour le choix des paramètres influençant la dose interne; les critères pour déterminer l'impact des résultats de la surveillance; l'interprétation des résultats de la surveillance aux postes de travail; les incertitudes liées au recueil des échantillons, aux techniques d'analyse et aux conditions de travail; les cas particuliers suivants, concernant l'interprétation des données itératives issues des différentes méthodes de mesurage à des dates différentes, le traitement des données inférieures au seuil de décision, les données aberrantes et les estimations dosimétriques à l'embryon/fœtus et au nourrisson; le compte-rendu/la documentation; l'assurance de la qualité.
L'ISO 27048:2011 ne traite pas des éléments suivants: de la dosimétrie dans les cas litigieux; de la modélisation pour l'amélioration de la dosimétrie interne; de l'influence potentielle de l'action d'un agent décorporant (par exemple administration d'agents chélatants); de l'investigation des causes ou des implications d'une exposition; de la dosimétrie des blessures contaminées.

Radiološka zaščita - Ocena odmerka doze za spremljanje stanja delavcev glede notranje izpostavljenosti sevanju (ISO 27048:2011)

General Information

• Status: Not Published
• Publication Date: 01-May-2022
• Withdrawal Date: 01-Nov-2022
• ICS: 13.280 - Radiation protection
• Technical Committee: CEN/TC 430 - Nuclear energy, nuclear technologies, and radiological protection
• Drafting Committee: CEN/TC 430 - Nuclear energy, nuclear technologies, and radiological protection
• Current Stage: 4098 - Decision to abandon - Enquiry
• Start Date: 15-Sep-2022
• Completion Date: 11-Feb-2026
• Ref Project: oSIST prEN ISO 27048:2021 - Radiation protection - Dose assessment for the monitoring of workers for internal radiation exposure (ISO 27048:2011)

Overview

The standard prEN ISO 27048, titled Radiation protection - Dose assessment for the monitoring of workers for internal radiation exposure (ISO 27048:2011), issued by the European Committee for Standardization (CEN), establishes essential guidelines for evaluating internal radiation doses in occupational settings. It focuses on the systematic monitoring of workers exposed to internal contamination from radioactive substances and provides standardized procedures to ensure reliable, consistent dose assessments for compliance with radiation protection regulations.

This international standard is crucial in environments where workers risk contamination by radioactive materials, enabling accurate interpretation of bioassay and workplace monitoring data. By defining minimum requirements and structured assessment methodologies, the document helps organizations maintain safety, optimize resource use, and uphold regulatory obligations related to internal radiation exposure.

Key Topics

• Scope of Dose Assessment

  • Specifies minimum requirements for evaluating monitoring data from workers exposed internally to radioactive substances.
  • Covers dose assessment procedures applicable to routine and special monitoring programs.
  • Defines criteria and assumptions for selecting dose-critical parameters.

• Monitoring and Evaluation Procedures

  • Procedures for interpreting workplace and individual monitoring data, including air activity concentrations and bioassay results.
  • Handling uncertainties arising from measurement techniques, sampling variability, and working conditions.
  • Interpretation of multiple datasets obtained from different methods or at various times.

• Decision Thresholds and Limits

  • Defines critical values and decision thresholds for evaluating measured activities related to safety limits.
  • Guidance on managing data below detection limits and addressing outliers or rogue results.

• Special Considerations

  • Dose calculation methods for sensitive cases such as embryo, foetus, and infant exposures.
  • Recognition of the limits of applicability, including when more advanced dose assessment methods are necessary for high-dose scenarios.

• Documentation and Quality Assurance

  • Detailed recommendations for reporting and documenting dose assessments.
  • Emphasis on maintaining quality assurance throughout the monitoring and evaluation process.

• Exclusions

  • Not applicable to dosimetry related to legal litigation, enhancements to dosimetry models, decorporation treatment effects, cause investigations of exposures, or dosimetry for contaminated wounds.

Applications

• Occupational Radiation Safety Programs
  Organizations engaged in nuclear power, radiopharmaceutical, and industrial radiology sectors can apply the standard to ensure workers’ internal doses are assessed consistently, supporting regulatory compliance and workplace safety.

• Regulatory Compliance and Reporting
  Employers and radiation protection officers (RPOs) can use ISO 27048 to fulfill requirements for transparent and accurate documentation of internal exposure, facilitating audits and official reporting to authorities.

• Dose Assessment Harmonization
  Enables harmonized dose assessment protocols worldwide, allowing consistent inter-laboratory comparisons, exchange of dosimetric information, and certification or accreditation of monitoring services.

• Risk Management and Incident Response
  Provides structured guidance for monitoring during routine activities as well as special or abnormal exposure events, ensuring reliable dose quantification to inform protective actions.

• Quality Program Development
  Supports the development of robust quality assurance programs within radiation protection laboratories and monitoring entities, enhancing measurement accuracy and reliability.

Related Standards

• ISO 20553:2006 – Radiation protection - Monitoring of workers occupationally exposed to a risk of internal contamination with radioactive material
  Supports comprehensive internal contamination monitoring practices complementing dose assessment guidance.

• ISO 28218 – Radiation protection - Performance criteria for radiobioassay
  Specifies performance requirements for measurements used in internal dosimetry, enhancing measurement quality relevant to ISO 27048.

• ISO/IEC Guides 98-3, 99, 5725 series – Guidance on measurement uncertainty and accuracy
  These guides underpin the statistical and metrological principles applied in evaluating dose assessment data under ISO 27048.

Practical Value and Benefits

• Enables consistent and scientifically supported internal dose assessments for worker safety.
• Optimizes resource allocation by tailoring assessment effort according to exposure seriousness.
• Facilitates international collaboration by standardizing dose interpretation methods.
• Supports radiation protection programs by ensuring dose assessments are reliable and reproducible.
• Helps protect vulnerable populations such as pregnant workers by including dose calculation procedures for embryos and infants.

Employing prEN ISO 27048 provides radiation protection professionals with a robust framework for managing internal exposure data, promoting occupational health and regulatory compliance in radiation-prone industries.

Standards Content (Sample)

SLOVENSKI STANDARD
01-januar-2021
Radiološka zaščita - Ocena odmerka doze za spremljanje stanja delavcev glede
notranje izpostavljenosti sevanju (ISO 27048:2011)
Radiation protection - Dose assessment for the monitoring of workers for internal
radiation exposure (ISO 27048:2011)
Strahlenschutz - Dosisermittlung für die Überwachung der inneren Strahlungsbelastung
von beruflich strahlenexponierten Personen (ISO 27048:2011)
Radioprotection - Estimation de la dose interne dans le cadre de la surveillance des
travailleurs en cas d'exposition aux rayonnements (ISO 27048:2011)
Ta slovenski standard je istoveten z: prEN ISO 27048
ICS:
13.280 Varstvo pred sevanjem Radiation protection
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 27048
First edition
2011-01-15
Radiation protection — Dose assessment
for the monitoring of workers for internal
radiation exposure
Radioprotection — Estimation de la dose interne dans le cadre de la
surveillance des travailleurs en cas d'exposition aux rayonnements

Reference number
ISO 27048:2011(E)
©
ISO 2011
ISO 27048:2011(E)
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ii © ISO 2011 – All rights reserved

ISO 27048:2011(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.2
3 Terms and definitions .2
4 Symbols and abbreviated terms .6
5 Derivation of critical values for routine monitoring programmes.7
6 Procedure for the assessment of workplace monitoring data .10
7 Procedure for the assessment of individual monitoring data .12
8 Uncertainties.22
9 Special topics .26
10 Documentation .29
11 Reporting.29
12 Quality assurance.30
Annex A (informative) Predicted ranges of measured bioassay quantities, E(50) = 20 mSv .31
Annex B (informative) Scattering factors .72
Annex C (informative) Retention functions and excretion rates.74
Bibliography.75

ISO 27048:2011(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 organisations, 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 standardisation.
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 27048 was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies, and
radiological protection, Subcommittee SC 2, Radiological protection.
iv © ISO 2011 – All rights reserved

ISO 27048:2011(E)
Introduction
The doses resulting from internal radiation exposure arising from contamination by radioactive substances
cannot be measured directly. Workers are monitored by making systematic measurements of activity
concentrations in air, activity in the body or excretion rates (see ISO 20553). The quantitative interpretation of
such measured activities requires well-defined models and data describing the behaviour of radioactive
substances in the human body. Such models and comprehensive data are provided by the International
Commission on Radiological Protection (ICRP). The practical use of these models, however, requires
assumptions to be made regarding the circumstances of an intake event (either known or assumed) such as
information on the chemical and physical characteristics of the radioactive material to which the individual was
exposed and the length of the time interval between intake and measurement.
In the case of an abnormal event leading to significant intake of a radioactive substance an exhaustive
investigation may be justified to assess the internal dose as reliably as possible. The procedure to be applied
in such a situation strongly depends on the individual case and is less amenable to standardisation. However,
when monitoring workers, the great majority of measurements indicate minor, if not negligible, exposures. For
these cases, while it is important to ensure the reproducibility of dose assessments, it is also important to
optimise the effort and cost involved in making the interpretation.
Various intercomparison studies have revealed that, in spite of the availability of scientific support in the form
[1][2][3][4][5] [6][7][8][9][10][11][12][13][14][15][16]
of International Atomic Energy Agency (IAEA) and ICRP
recommendations, the actual application of identical models and data by different laboratories often results in
dose assessments differing by orders of magnitude. There is, therefore, a need to lay down standard
procedures for assessing internal doses using exposure data, body activities or excretion rates, in order to
achieve consistency and reliability in the assessment of doses.
This International Standard should improve the reproducibility of dose assessments while ensuring that the
level of effort required for data interpretation is commensurate with the seriousness of the exposure. It should
enable the exchange of consistent dosimetric information among laboratories and authorities, including across
international borders. It is expected that it form the basis for certification, accreditation or approval in this field,
for which there is a growing demand.

INTERNATIONAL STANDARD ISO 27048:2011(E)

Radiation protection — Dose assessment for the monitoring of
workers for internal radiation exposure
1 Scope
This International Standard specifies the minimum requirements for the evaluation of data from the monitoring
of workers occupationally exposed to the risk of internal contamination by radioactive substances. It presents
procedures and assumptions for the standardised interpretation of monitoring data, in order to achieve
acceptable levels of reliability. Those procedures allow the quantification of exposures for the documentation
of compliance with regulations and radiation protection programmes. Limits are set for the applicability of the
procedures in respect of the dose levels above which more sophisticated methods will have to be applied.
This International Standard addresses the following:
a) procedures for dose assessment based on reference levels for routine and special monitoring
programmes;
b) assumptions for the selection of dose-critical parameter values;
c) criteria for determining the significance of monitoring results;
d) interpretation of workplace monitoring results;
e) uncertainties arising from sampling, measurement techniques and working conditions;
f) the special topics of
1) interpretation of multiple data arising from different measurement methods at different times,
2) handling data below the decision threshold,
3) rogue data, and
4) calculation of doses to the embryo/foetus and infant;
g) reporting/documentation;
h) quality assurance.
It is not applicable to the following:
⎯ dosimetry for litigation cases;
⎯ modelling for the improvement of internal dosimetry;
⎯ the potential influence of decorporation measures (e.g. administration of chelating agents);
⎯ the investigation of the causes or implications of an exposure;
⎯ dosimetry for contaminated wounds.
ISO 27048:2011(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/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated terms
(VIM)
ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results — Part 1: General
principles and definitions
ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
ISO 5725-3, Accuracy (trueness and precision) of measurement methods and results — Part 3: Intermediate
measures of the precision of a standard measurement method
ISO 20553:2006, Radiation protection — Monitoring of workers occupationally exposed to a risk of internal
contamination with radioactive material
ISO 28218, Radiation protection — Performance criteria for radiobioassay
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC Guide 99, ISO 5725-1,
ISO 5725-2 and ISO 5725-3 and the following apply.
3.1
absorption
absorption characterised by its rate in the deposited material and which, depending on the material, is
denoted as being of type F, M or S
3.1.1
absorption type F
deposited materials that have high (fast) rates of absorption into body fluids from the respiratory tract
3.1.2
absorption type M
deposited materials that have intermediate (moderate) rates of absorption into body fluids from the respiratory
tract
3.1.3
absorption type S
deposited materials that have low (slow) rates of absorption into body fluids from the respiratory tract
3.2
activity
number of spontaneous nuclear disintegrations per unit time
NOTE The activity is stated in becquerels (Bq), i.e. the number of disintegrations per second.
2 © ISO 2011 – All rights reserved

ISO 27048:2011(E)
3.3
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.
3.4
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.
3.5
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
3.6
critical value
maximum value for the result of a single measurement in a monitoring programme where it is safe to assume
that the corresponding extrapolated annual dose will not exceed a predefined dose level
3.7
decision threshold
fixed value of the measurand by which, when exceeded by the result of an actual measurement of a
measurand quantifying a physical effect, it is decided that the physical effect is present
NOTE The decision threshold is the critical value of a statistical test for the decision between the hypothesis that the
physical effect is not present and the alternative hypothesis that it is present. When this value is exceeded by the result of
an actual measurement, this is taken to indicate that the hypothesis should be rejected. The statistical test shall be
designed such that the probability of wrongly rejecting the hypothesis (error of the first kind) is at most equal to a given
value, α.
3.8
detection limit
smallest true value of the measurand which is detectable by the measuring method
NOTE The detection limit is the smallest true value of the measurand which is associated with the statistical test and
hypothesis according to in vivo measurement (3.14) by the following characteristics: if, in reality, the true value is equal
to or exceeds the detection limit, the probability of wrongly not rejecting the hypothesis (error of the second kind) shall be
at most equal to a given value, β.
[17]
3.9 Doses
3.9.1
annual dose
committed effective dose resulting from all intakes occurring during a calendar year
NOTE The term “annual dose” is not used to represent the dose received in a year from all preceding intakes.
3.9.2
committed effective dose
time integral of the equivalent dose rate over an integration period, which, in the context of this International
Standard, is 50 years following any intake
ISO 27048:2011(E)
3.9.3
effective dose
sum of weighted equivalent doses in all tissues and organs of the body
3.10
excretion function
fraction of an intake excreted per day after a given time has elapsed since the intake occurred
3.11
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
3.12
intake
activity of a radionuclide taken into the body in a given time period or as a result of a given event
3.13
in vitro analyses
indirect measurements
analyses including measurements of radioactivity present in biological samples taken from an individual
NOTE These include urine, faeces and nasal samples; in special monitoring programmes, samples of other materials
such as blood and hair may be taken.
3.14
in vivo measurement
direct measurements
measurement of radioactivity present in the human body carried out using detectors to measure the radiation
emitted
NOTE Normally, the measurement devices are whole-body or partial-body (e.g. lung, thyroid) counters.
3.15
monitoring
measurements made for the purpose of assessment or control of exposure to radioactive material and the
interpretation of the results
NOTE This International Standard distinguishes four different categories of monitoring programmes, namely
confirmatory monitoring programme (3.15.1.1), routine monitoring programme (3.15.1.2), special monitoring
programme (3.15.1.3), and task-related monitoring programme (3.15.1.4), as well as two different types of monitoring,
namely individual monitoring (3.15.2.1) and workplace monitoring (3.15.2.2), which feature in each category.
3.15.1 Categories of monitoring programme
3.15.1.1
confirmatory monitoring programme
monitoring programme carried out to confirm assumptions about working conditions
EXAMPLE Monitoring programme carried out to confirm that significant intakes have not occurred.
3.15.1.2
routine 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
3.15.1.3
special monitoring programme
monitoring programme performed to quantify significant exposures following actual or suspected abnormal
events
4 © ISO 2011 – All rights reserved

ISO 27048:2011(E)
3.15.1.4
task-related 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
3.15.2 Types of monitoring
3.15.2.1
individual monitoring
monitoring by means of equipment worn by individual workers, by measurement of the quantities of
radioactive materials in or on the bodies of individual workers, or by measurement of radioactive material
excreted by individual workers
3.15.2.2
workplace monitoring
monitoring using measurements made in the working environment
3.16
monitoring interval
period between two consecutive times of measurement
3.17
quality assurance
planned and systematic actions necessary to provide adequate confidence that a process, measurement or
service will satisfy given requirements for quality such as those specified in a licence
3.18
quality control
part of quality assurance intended to verify that systems and components correspond to predetermined
requirements
3.19
quality management
all activities of the overall management function that determine the quality policy, objectives and
responsibilities, and that 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, specified by the employer or the regulatory authority, at or above which values of dose received
by workers are to be entered in their individual records
3.21
reference level
investigation level or recording level
3.22
retention function
function describing the 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
3.23
scattering factor
geometric standard deviation of the lognormal distribution of bioassay measurements
ISO 27048:2011(E)
3.24
time of measurement
〈in vitro analysis〉 time at which the biological sample (e.g. urine, faeces) was taken from the individual
concerned
3.25
time of measurement
〈in vivo analysis〉 time at which the measurement begins
4 Symbols and abbreviated terms
α probability of falsely claiming the presence of activity in a sample
β probability of falsely claiming the absence of a component in a sample
D annual committed effective dose (Sv) such that lower doses may be discounted for the purpose of
v
the monitoring programme (maximum value: 0,1 mSv)
E level of annual dose (Sv) such that lower doses may be considered negligible for the purpose of the
v
monitoring programme (maximum value: 0,1 mSv)
E(50) committed effective dose
e(50) dose coefficient: committed effective dose per unit intake
f gastro-intestinal uptake factor
A
I intake
L (I) likelihood function
i
m(t) predicted value of the measured quantity at time, t, for unit intake (excretion or retention function at
time, t , for unit intake)
i
m (t) predicted value of the quantity measured after a period of t days of a chronic unit intake per day
c
(excretion or retention function at time, t , for chronic unit intake per day)
i
M measurement value at time, t
i i
M critical value
c
n in routine monitoring, number of monitoring intervals in a calendar year, i.e. 365/ΔT
P activity to be measured (in vitro or in vivo) corresponding to all known, already documented intakes
N number of measurements below the decision threshold
K scattering factor of the monitoring method applied
SF
ΔT duration of the monitoring interval (in days)
t time of the current measurement
m
t time of the assumed intake
i
∗
y decision threshold
6 © ISO 2011 – All rights reserved

ISO 27048:2011(E)
5 Derivation of critical values for routine monitoring programmes
Critical values, M — the maximum value for the result of a single measurement where the corresponding
c
extrapolated annual dose will not exceed a predefined dose level — shall be derived for each routine
monitoring programme. This dose level shall be set such that lower doses may be considered negligible
(i.e. reported as zero dose). For measurement results below M , there is no need to evaluate the intake or
c
dose explicitly: the dose may be regarded as insignificant. The measured value (if above the decision
threshold) shall be recorded in order to document the fact that the measurement was carried out and to
provide information to support any possible future reassessment of dose.
The annual committed effective dose, D , selected as the dose level for the derivation of M shall not exceed
v c
0,1 mSv, unless required differently in national law.
The critical value, M , for an individual routine monitoring programme depends on
c
⎯ the monitoring interval determined in accordance with ISO 20553, and
⎯ the distribution and retention in the body or the excretion rate from the body of the contaminant.
Critical values may be calculated for air concentrations provided that these calculations are based on a
realistic assessment of the air concentration in the breathing zone of the worker.
Assuming a single acute intake at the midpoint of the monitoring interval, M for a routine monitoring
c
programme can be calculated using Equation (1):
Dm×Δ(/T2)
ΔT
v
M=× (1)
c
e 50 365
()
where
D is the level of annual dose (Sv) such that lower doses may be discounted for the purpose of the
v
monitoring programme;
m(ΔT/2) is, for in vitro measurements, the value of the excretion function at time ΔT/2 (days) after a unit
intake, and, for in vivo measurements, the value of the retention function at time ΔT/2 (days)
after a unit intake;
e(50) is the dose coefficient: the committed effective dose per unit intake for inhalation (appropriate
absorption type).
Equation (1) is based on the assumption that only one radionuclide is incorporated. For mixtures of
radionuclides, typical isotope ratios (weighted by the dose coefficients) shall be applied to reduce M .
c
Critical values, M for D = 0,1 mSv for each in vitro and in vivo measurement are given in Tables 1 to 5 for
c v
the selected radionuclides and the monitoring intervals defined in ISO 20553 for a routine monitoring
programme.
The fact that nuclides and critical values are listed in Tables 1 to 5 does not imply that the corresponding
measurement method alone is adequate for routine monitoring. For some of the nuclides, actual detection
limits do not fulfil the requirements of ISO 20553. Data for these nuclides are provided to give a numerical
basis for decisions on whether the monitoring method is appropriate. The measurements for which numbers
are given may supplement other monitoring procedures, e.g. workplace monitoring.
ISO 27048:2011(E)
Table 1 — Critical values for urine analysis for a routine
monitoring programme corresponding to D = 0,1 mSv
v
Max. time intervals for Critical values for
a
Radionuclide Absorption type urine measurements 0,1 mSv
days Bq/24h
3 b
H HTO 30 4 000
Organic 7 10
C
Dioxide 180 300
32 b
P F 30 10
33 b
P F 30 100
S F 7 20
Ni M 15 3
F 30 10
Sr
S 30 5 E-2
F 30 1
Sr
S 180 3 E-3
Ra M 180 1 E-4
c
Uranium (natural)
F 90 1 E-2
hexafluoride
c
Uranium (natural)
peroxide, nitrate, F 30 2 E-2
ammonium diuranate
Uranium (natural)
M 90 3 E-3
tetrafluoride, trioxide
Uranium (natural)
S 90 2 E-5
dioxide, octoxide
Np M 180 1 E-4
Pu S 180 7 E-7
Pu S 180 1 E-6
Pu M 180 1 E-5
Am M 180 3 E-5
Cm M 180 3 E-5
a
For some of the nuclides, actual detection limits do not fulfil the requirements of ISO 20553. Data for these
nuclides are provided to give a numerical basis for decisions on whether the monitoring method is appropriate.
b
Expressed in becquerels per litre (Bq/l).
c
Based on biokinetic data published in [18].

8 © ISO 2011 – All rights reserved

ISO 27048:2011(E)
Table 2 — Critical values for faecal analysis for a routine
monitoring programme corresponding to D = 0,1 mSv
v
Max. time intervals for Critical values for
a
Radionuclide Absorption type faecal measurements 0,1 mSv
days Bq/24h
Uranium (natural)
M 180 2 E-3
tetrafluoride, trioxide
Uranium (natural) dioxide,
S 180 9 E-4
octoxide
Th S 180 2 E-4
Th S 180 5 E-4
Th M 180 2 E-4
Np M 180 7 E-2
Pu S 180 5 E-4
Pu S 180 7 E-4
Pu M 180 1 E-4
Am M 180 2 E-4
Cm M 180 4 E-4
a
For some of the nuclides, actual detection limits do not fulfil the requirements of ISO 20553. Data for these
nuclides are provided to give a numerical basis for decisions on whether the monitoring method is appropriate.

Table 3 — Critical values for whole body measurements for a routine
monitoring programme corresponding to D = 0,1 mSv
v
Max. time intervals for
Critical values for
whole body
Radionuclide Absorption type 0,1 mSv
measurements
Bq
days
Cr F 15 20 000
Mn M 90 1 000
Fe M 90 400
Co S 180 2 000
Co S 180 500
Co S 180 100
Se M 180 4 000
110m
Ag S 180 200
Cs F 180 2 000
ISO 27048:2011(E)
Table 4 — Critical values for lung measurements for a routine
monitoring programme corresponding to D = 0,1 mSv
v
Max. time intervals for Critical values for
Radionuclide Absorption type lung measurements 0,1 mSv
days Bq
Uranium ( U)
M 180 0,6
tetrafluoride, trioxide
Uranium ( U) dioxide,
S 180 0,3
octoxide
Am M 180 0,04
Table 5 — Critical values for thyroid measurements for a routine
monitoring programme corresponding to D = 0,1 mSv
v
Max. time intervals for Critical values for
Radionuclide Absorption type thyroid measurements 0,1 mSv
days Bq
I F 90 200
I F 15 30
6 Procedure for the assessment of workplace monitoring data
The measurement or assessment of concentrations of radioactivity in air may be used to quantify workers'
exposure if the monitoring programme does not require mandatory individual measurements. The following
assessment procedure assumes that the measured activity concentration is representative of the air in the
breathing zone.
The general procedure is described in Figure 1.
If the measurement does not give an activity concentration above the decision threshold of the method applied,
the fact that the measurement was performed is documented and no further evaluation is required.
If the measured value indicates an extraordinary event, an investigation shall be carried out to determine the
reasons for the elevated result and documented. If this investigation does not exclude a dose exceeding 30 %
of the annual dose limit, an individual dose assessment shall be undertaken. An extraordinary event here
means that the measured value significantly exceeds the estimates or assumptions on which the monitoring
programme was based, e.g. exceeding the 95th percentile of available long-term observations.
The dose corresponding to a measured activity concentration in air is calculated using Equation (2):
EC(50)=×ΔT×e (50)×9,6 (2)
iim, i
where
e(50) is the dose coefficient: the committed effective dose per unit intake for inhalation (appropriate
absorption type);
i is the index for the nuclide present in the inhaled air;
C is the measured concentration of radionuclide i (in Bq/m );
m,i
3 [7]
9,6 is the coefficient reflecting the volume of air breathed during light physical activity (in m /d) .
10 © ISO 2011 – All rights reserved

ISO 27048:2011(E)
When tritium intakes are monitored by air sampling (e.g. itinerant workers in nuclear power plants), the value
[6]
resulting from Equation (2) shall be multiplied by a factor of 1,5 in order to account for uptakes via skin .
The dose calculated in this way shall be documented as the dose for the monitoring interval, unless it exceeds
the investigation level defined when setting up the monitoring procedure, in which case exposure estimates
will need to be confirmed by additional investigations (see ISO 20553).
Measurement of airborne
radioactivity
Document that
measurement was
no
Value above decision threshold?
performed.
yes
Indication of
extraordinary event?
no
Calculated dose on the basis of default
models and with default assumptions on
exposure conditions
yes
Document
Dose *n > measurement, dose,
no
investigation level?
ID for process.
yes
Special (individual ) monitoring

Figure 1 — Flow chart for interpretation of measured activity concentrations in air
ISO 27048:2011(E)
7 Procedure for the assessment of individual monitoring data
The procedure for interpreting single results of individual monitoring measurements is described in Figure 2,
7.1 describes the procedure for dose assessment based on routine monitoring and 7.2 describes the
differences in this procedure that apply to the evaluation of special monitoring.
7.1 Results of routine monitoring
The procedure for assessing doses on the basis of routine monitoring results is described on the left-hand
side of Figure 2.
12 © ISO 2011 – All rights reserved

ISO 27048:2011(E)
Measurement performed Measurement performed
for routine monitoring for special monitoring
STEP 1:
Uptake via wound and
Interval and method appropriate
influence of decorporation
no
for routine monitoring? therapy can be ruled out?
yes yes
Document that
STEP 2:
measurement was
no no Value significant?
Value significant?
performed.
yes
yes
STEP 3:
Calculate dose on the basis of default
Calculate dose
models and with default assumptions
on the basis of default models
on exposure conditions
STEP 4:
Considering uncertainties
Considering uncertainties
Document
of measurements:
of measurements:
measurement ,
no no
dose K × E (50) > 5 %
SF
n × K × E (50) > 5 %
SF
of the annual dose limit?
of the annual dose limit?
yes
yes
STEP 5:
Confirm assumptions/findings by
Unexpected exposures no
additional measurements
excluded?
no
yes
STEP 6:
Considering uncertainties
Document
Considering uncertainties
of parameters describing measurement,
of parameters describing
no no
exposure situation: annual dose assessed dose,
exposure situation: annual dose
limits potentially exceeded? model parameter,.
limits potentially
exceeded?
yes
STEP 7:
Decrease uncertainty with available
case-specific information
Document
STEP 8:
measurement,
annual dose limit potentially no
assessed dose,
exceeded?
yes
model parameter,.
yes Go to expert assessment
Figure 2 — Procedure for assessment of doses on basis of individual measurements
ISO 27048:2011(E)
7.1.1 Step 1 — Appropriateness of measurement
The first question to be answered is whether the measurement is suitable for treatment by standard
procedures. A check shall be made of whether the method of monitoring and the time interval since the
previous measurement are appropriate to the radionuclide or material and absorption type according to
ISO 20553. The time interval shall not deviate from that given in ISO 20553 by more than the tolerance
specified in ISO 20553:2006, Table 6. Also, if a worker is only employed for a period shorter than the
nuclide-specific monitoring interval defined in ISO 20553, the standard procedure for interpreting results of
routine monitoring is not appropriate.
If one of these conditions is not fulfilled, the interpretation of the measured value shall be made according to
the procedure for special monitoring (see 7.2).
7.1.2 Step 2 — Significance
A measured value shall be judged to be significant, if
⎯ the value exceeds the decision threshold, y*, of the measurement method, and
⎯ the value is above the critical value, M .
c
The comparison of the measured value with M should be based on the absolute amounts of radionuclides
c
present in urine or faecal samples; i.e. no attempt should be made to subtract natural background levels.
If one of these criteria is not fulfilled, it is sufficient to document the measurement without further evaluation.
If the measured value is found to be significant before continuing with Step 3, a test should be made as to
whether the measured value is attributable to earlier intakes already quantified and documented.
7.1.2.1 Contributions from earlier intakes
The calculation of contributions from earlier intakes shall use Equation (3):
PI=×m()t−t (3)
∑iim
i
where
P is the activity to be measured (in vitro or in vivo) corresponding to all known, already documented
intakes;
i is the index for the intake events previously identified;
I is all intakes (in Bq) potentially contributing to the measured value actually to be analysed (in Bq);
i
t is the time of the intake;
i
t is the time of the current measurement.
m
7.1.2.2 Test of significance of earlier contributions
By means of the scattering factors, K , given in 8.3.2 and Annex B, the significance of earlier contributions
SF
(P) shall be tested as follows.
14 © ISO 2011 – All rights reserved

ISO 27048:2011(E)
If the measured value, M, lies in the interval of
P
< SF
K
SF
then this indicates that there is no significant contribution by new intakes. In this case it is sufficient to
document the measurement without further evaluation. If the measured value, M, is according to Equation (5)
P
M < (5)
K
SF
then this indicates a discrepancy between the earlier assessments and the present value. If the earlier
assessments can be confirmed, the present measurement shall be repeated. If the earlier assessments
cannot be confirmed, their contribution to the present measurement shall be ignored. If the measured value, M,
is according to Equation (6)
MP>×K (6)
SF
then the measured value is the consequence of an intake not yet analysed. In this case, the measurement
may be interpreted by the standard dose assessment given in 7.1.3.
7.1.3 Step 3 — Standard dose assessment
In the standard dose assessment, the dose corresponding to the measured value shall be calculated using the
following default assumptions:
⎯ the intake was an acute event at the midpoint of the monitoring interval;
⎯ the exposure was via inhalation of material with AMAD = 5 µm;
[8]
⎯ the absorption type, the retention and the excretion rates are as described by the ICRP 68 and
[12]
ICRP 78 default values.
Alternatively, where site-specific default values are available and documented, these may be used, provided
they are shown to be appropriate for the process in which the individual was engaged.
NOTE An assumption of a chronic and constant intake rate might better represent constant intake probabilities and
result in unbiased estimates. Nevertheless, the assumption of an acute intake event is chosen here for reasons of
consistency with ICRP recommendations.
Equations (7) and (8) shall be used for the calculation of the intake during the monitoring interval and the
committed effective dose, E(50), resulting from that intake:
M ′
I = (7)
mTΔ /2
()
Ee50=×50I (8)
() ( )
where
M′ equals either the measured value M or M − P, if the contributions, P, from earlier intakes have been
calculated according to 7.1.2.1;
I is the intake (in Bq).
ISO 27048:2011(E)
[12]
Values for m(t) (retention function or excretion rate) are given in Annex C and correspond to ICRP 78 . They
shall be used unless there are more recent data published by ICRP.
EXAMPLE Numerical application for Equations (7) and (8):
A worker handles iodine-131( I), type F compound (AMAD = 5 µm). A routine monitoring programme by thyroid
(in vivo) monitoring with a 14 day interval yielded the following results: 360 Bq.
ΔT = time interval = 14 days with ΔT/2 = 7 days
M′ = measured value = 360 Bq
m(ΔT/2) = retention in the thyroid after single intake in Bq per Bq incorporated activity for I-131,at t = 7 days,
−2 −1
m(7) = 7,4⋅10 Bq.Bq (according to Annex C, part 1, for I-131)

−2
According to Equation (7): I = 360/7,4⋅10 = 4 865 Bq
−8 −5
According to Equation (8): E(50) = e(50) × I = 1,1⋅10 × 4 865 = 5⋅10 Sv
[dose coefficient e(50) taken from [27]].
For exposures to mixtures of radionuclides where measured values M′ have been obtained for each
radionuclide, Equations (7) and (8) should be used directly, and the values of E(50) for each nuclide summed
before proceeding to Step 4. If a measured value for one radionuclide M′ is to be used not only to determine
a
E (50) but also to infer the committed effective dose resulting from an intake of another radionuclide, E (50),
a b
then this should be done by multiplying E (50) by the product of I /I and e (50)/e (50). I /I may be
a b a b a b a
determined from the isotopic activity ratio for the radionuclides present in the material to which the worker was
exposed. The values of E(50) for each nuclide should then be summed before proceeding to Step 4.
7.1.4 Step 4 — Criterion for accepting the standard dose assessment
There is no need for further evaluation if, for the calculated dose E(50), Equation (9) is valid:
nK××E 50< 0,05×E (9)
()
SF limit
where
n is the number of monitoring intervals per year (= 365/ΔT);
E is the annual dose limit.
limit
In this case, the calculated intake for the monitoring interval and the corresponding committed effective dose
shall be documented. This dose is the documented best estimate and is used for determining formal
compliance with dose limits.
If more than one radionuclide is monitored, the sum of their contributions to the committed effective dose
during the monitoring interval shall be used in the comparison in Equation (9).
The scattering factors are given in Annex B. They reflect the uncertainties resulting from sampling and
measuring, and they are defined under the assumption of lognormal distributions, which requires that Type A
errors be small (below 30 %). Alternatively, where site-specific scattering factors are available and
documented, these may be used, provided that they are shown to be appropriate for the process in which the
individual was engaged.
16 © ISO 2011 – All rights reserved

ISO 27048:2011(E)
7.1.5 Step 5 — Unexpected exposures
When specifying a routine monitoring programme, it is generally assumed that work processes and workplace
conditions do not vary greatly over time. An additional check should therefore be made to determine whether
the measured value is consistent with earlier experience. An unusual value could indicate a deviation from the
normal conditions that were assumed to prevail when the routine monitoring programme was defined.
Additionally, the comparison of results for different workers with comparable exposure situations may be
helpful in identifying unexpected exposure situations.
Therefore, it is recommended that adequate quantitative criteria be set up in advance for the identification of
exposures for which the application of previously defined assumptions is questionable, and for which further
investigations are required.
7.1.6 Step 6 — Comparison with dose limits
If the dose calculation following Equations (7) and (8) results in an estimate exceeding 5 % of the annual dose
limit [i.e. the condition in Equation (9) is not fulfilled], and if there is no evidence for an unexpected exposure,
then the next step consists of a test of whether annual dose limits may be exceeded.
The procedure described below enables a decision to be made as to whether the dose can reliably be
assumed to lie below the dose limit, in order for the further course of investigation to be determined. It takes
account of uncertainty in the material-specific parameters that have the greatest effect on dose. The
procedure is not intended to be used for determining formal complia
...