ISO 20043-1:2021

INTERNATIONAL ISO
STANDARD 20043-1
First edition
2021-01
Measurement of radioactivity in
the environment — Guidelines for
effective dose assessment using
environmental monitoring data —
Part 1:
Planned and existing exposure
situation
Mesurage de la radioactivité dans l'environnement — Lignes
directrices pour l’évaluation de la dose efficace à l’aide de données de
surveillance environnementale —
Partie 1: Situation d'exposition existante et planifiée
Reference number
©
ISO 2021
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 5
5 Principle . 5
6 Assessing and monitoring human exposure. 8
7 Environmental monitoring program .10
7.1 General .10
7.2 Planning process .11
7.2.1 Selection of the sampling strategy .11
7.2.2 Description of the sampling plan .11
7.3 Sampling process .11
7.3.1 Collection of samples .11
7.3.2 Preparation of the sorted sample .12
7.4 Laboratory process .12
7.4.1 Handling of the laboratory sample .12
7.4.2 Preparation of the test sample .12
8 Environmental monitoring to assess external exposure .12
8.1 General .12
8.2 Direct measurement of the external dose .13
8.3 Indirect assessment of the external dose .14
8.3.1 External exposure from contaminated soil .14
8.3.2 External exposure from contaminated air .15
9 Environmental monitoring to assess internal exposure .15
9.1 General .15
9.2 Inhalation.16
9.3 Ingestion .17
9.3.1 General.17
9.3.2 Ingestion of water .17
9.3.3 Ingestion of agricultural products .18
10 Radioactivity measurement .18
10.1 General .18
10.2 Soil .18
10.3 Water .19
10.4 Food stuffs .20
11 Variability and uncertainty .21
12 Quality assurance and quality control program .21
Annex A (informative) Example of sampling procedures for environmental and food matrices .23
Annex B (informative) Example of sample preparation methods for environmental and
food matrices .24
Annex C (informative) Investigation to identify the cause of increase of ambient dose and
activity concentration of environmental samples above their background levels.25
Bibliography .26
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO's adherence to the World Trade Organization (WTO)
principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary
information
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, Subcommittee SC 2, Radiological protection.
A list of all the parts in the ISO 20043 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved

Introduction
Everyone is exposed to natural radiation. The natural sources of radiation are cosmic rays and naturally
occurring radioactive substances existing in the Earth itself and inside the human body. Human
activities involving the use of radiation and radioactive substances (NORM) cause radiation exposure in
addition to the natural exposure. Some of those activities, such as the mining and use of ores containing
naturally-occurring radioactive substances and the production of energy by burning coal that contains
such substances, simply enhance the exposure from natural radiation sources. Nuclear installations
use radioactive materials and produce radioactive effluent and waste during operation and on their
decommissioning. The use of radioactive materials in industry, agriculture and research is expanding
around the globe.
All these human activities generally also give rise to radiation exposures that are only a small fraction
of the global average level of natural exposure. The medical use of radiation is the largest and a growing
man-made source of radiation exposure in developed countries. It includes diagnostic radiology,
radiotherapy, nuclear medicine and interventional radiology.
Radiation exposure also occurs as a result of occupational activities. It is incurred by workers in
industry, medicine and research using radiation or radioactive substances, as well as by passengers
and crew during air travel and for astronauts. The average level of occupational exposures is generally
[1]
similar to the global average level of natural radiation exposure .
As the uses of radiation increase, so do the potential health risks and the public’s concerns increase.
Thus, all these exposures are regularly assessed in order to
a) improve the understanding of global levels and temporal trends of public and worker exposure,
b) evaluate the components of exposure so as to provide a measure of their relative importance, and
c) identify emerging issues that may warrant more attention and scrutiny. While doses to workers
are usually directly measured, doses to the public are usually assessed by indirect methods
using radioactivity measurement results performed on various sources: waste, effluent and/or
environmental samples.
To ensure that the data obtained from radioactivity monitoring programs support their intended use,
it is essential in the dose assessment process that stakeholders (the operators, the regulatory bodies,
the local information committee and associations, etc.) agree on appropriate data quality objectives,
methods and procedures for: the sampling, handling, transport, storage and preparation of test
samples; the test method; and for calculating measurement uncertainty. An assessment of the overall
measurement uncertainty also needs to be carried out systematically. As reliable, comparable and ‘fit
for purpose’ data are an essential requirement for any public health decision based on radioactivity
measurements, international standards of tested and validated radionuclide test methods are an
important tool for the production of such measurement results. The application of standards serves
also to guaranty comparability over time of the test results and between different testing laboratories.
Laboratories apply them to demonstrate their technical competences and to complete proficiency tests
successfully during interlaboratory comparisons, two prerequisites to obtain national accreditation.
Today, over a hundred international standards, prepared by Technical Committees of the International
Organization for Standardization, including those produced by ISO/TC 85 working groups, and the
International Electrotechnical Commission, are available for measuring radionuclides in different
matrices by testing laboratories.
Generic standards help laboratories to manage the measurement process and specific standards
describing test methods are used specifically by those in charge of radioactivity measurement. These
later cover test methods for:
40 3 14
— Natural radionuclides, including K, H, C and those originating from the thorium and uranium
226 228 234 238 220 222 210
decay series, in particular Ra, Ra, U, U, Rn, Rn, Pb, which can be found in every
material from natural sources or can be released from technological processes involving naturally
occurring radioactive materials (e.g. the mining and processing of mineral sands or phosphate
fertilizer production and use), and
— Man-made radionuclides, such as transuranium elements (americium, plutonium, neptunium, and
3 14 90
curium), H, C, Sr and gamma emitting radionuclides found in waste, liquid and gases effluent
and in environmental matrices (air, soil, water, biota) as a result of authorized releases into the
environment and of fallout resulting from the explosion in the atmosphere of nuclear devices and
accidents, such as those that occurred in Chernobyl and Fukushima. Radionuclides, such as H and
C occur both naturally and as by-products of the operation of nuclear reactors.
[2]
The ICRP recognises three types of exposure situations that are intended to cover the entire range of
exposure situations: planned, emergency and existing exposure situations. Planned exposure situations
involve the planned introduction and operation of sources (previously categorised as practices).
Emergency exposure situations are situations requiring prompt action in order to avoid or to reduce
adverse consequences. Existing exposure situations are exposure situations that already exist when
a decision on control is taken, such as those caused by enhanced natural background radiation (e.g.
exposure to radon in existing buildings).
The fraction of the background dose rate to man from environmental radiation, mainly gamma
radiation, is very variable and depends on factors such as the radioactivity of the local rock and soil, the
nature of building materials and the construction of buildings in which people live and work.
This document sets out principles and guidance for the radiological characterisation of the environment
needed for checking the results of
— prospective assessment of dose to the public arising from exposure to ionizing radiation which
may arise from planned discharges to the atmosphere and to the aquatic environment or following
remediation action;
— retrospective assessment for dose that may be made for discharges or disposals that were not initially
covered by an authorization/permit delivered by a national regulatory body (e.g. contaminated land
or dose associated with accidental releases of radionuclides into the environment).
This document is one of a set of generic ISO Standards on measurement of radioactivity.
Example of dose assessment in different exposure situations, modified from Reference [3]
Type of assessment
Situation
Prospective Retrospective
Planned Determining compliance with Estimating dose to the public from past
the relevant dose constraint (dose limit operations
or regulatory requirements). A prospective
assessment includes the exposures expected
to occur in normal operation.
Existing Future prolonged exposures (e.g. after Past exposures (e.g. occupancy
remediation) of contaminated lands)
Emergency Emergency planning (operational Actual impacts after emergency
intervention level)
vi © ISO 2021 – All rights reserved

INTERNATIONAL STANDARD ISO 20043-1:2021(E)
Measurement of radioactivity in the environment —
Guidelines for effective dose assessment using
environmental monitoring data —
Part 1:
Planned and existing exposure situation
1 Scope
These international guidelines are based on the assumption that monitoring of environmental
components (atmosphere, water, soil and biota) as well as food quality ensure the protection of
[2][4][5][6][7][8]
human health . The guidelines constitute a basis for the setting of national regulations
and standards, inter alia, for monitoring air, water and food in support of public health, specifically to
protect the public from ionizing radiation.
This document provides
— guidance to collect data needed for the assessment of human exposure to radionuclides naturally
present or discharged by anthropogenic activities in the different environmental compartments
(atmosphere, waters, soils, biological components) and food;
— guidance on the environmental characterization needed for the prospective and/or retrospective
dose assessment methods of public exposure;
— guidance for staff in nuclear installations responsible for the preparation of radiological assessments
in support of permit or authorization applications and national authorities’ officers in charge of
the assessment of doses to the public for the purposes of determining gaseous or liquid effluent
radioactive discharge authorizations;
— information for the public on the parameters used to conduct a dose assessment for any exposure
situations to a representative person/population. It is important that the dose assessment process
be transparent, and that assumptions are clearly understood by stakeholders who can participate
in, for example, the selection of habits of the representative person to be considered.
Generic mathematical models used for the assessment of radiological human exposure are presented
to identify the parameters to monitor, in order to select, from the set of measurement results, the "best
estimates" of these parameter values. More complex models are often used that require the knowledge
of supplementary parameters.
The reference and limit values are not included in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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
me a s ur ement (GUM: 1995)
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated
terms (VIM)
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
3 Terms and definitions
For the purposes of this document, the definitions given in ISO 80000-10, ISO/IEC Guide 98-3,
ISO/IEC Guide 99, and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
background
doses, dose rates or activity concentrations associated with natural sources, or any other sources in the
environment that are not amenable to control
3.2
conversion coefficient
coefficient giving effective dose in an external exposure
3.3
data quality objectives
statement of the required detection limits, accuracy, reproducibility and repeatability of the required
analytical and other data
Note 1 to entry: Generic data quality objectives can sometimes be set at national level. Data quality objectives
can also embrace an amount of data required for an area of land (or part of a site) to enable sound comparison
with generic guidelines or standards or for a site-specific or material-specific estimation of risk.
3.4
dose assessment
assessment of the dose(s) to an individual or group of people
Note 1 to entry: For example, assessment of the dose received or committed by an individual on the basis of
results from workplace monitoring or bioassay.
Note 2 to entry: the term exposure assessment is also sometimes used.
3.5
dose coefficient
coefficient giving the committed effective dose from an internal exposure
3.6
emergency exposure situations
situation of exposure arising as a result of an accident, a malicious act or other unexpected event that
requires prompt action in order to avoid or to reduce adverse consequences
3.7
existing exposure situations
situation of exposure that already exists when a decision on the need for control needs to be taken
Note 1 to entry: Existing exposure situations include exposure to natural background radiation that is amenable
to control; exposure due to residual radioactive material that derives from past practices (3.13) that were never
subject to regulatory control; and exposure due to residual radioactive material deriving from a nuclear or
radiological emergency after an emergency has been declared to be ended.
2 © ISO 2021 – All rights reserved

3.8
hazard
potential for harm or detriment, especially for radiation risks; a factor or condition that might operate
against safety
3.9
intended use
use in accordance with information provided with a product or system, or, in the absence of such
information, by generally understood patterns of usage
3.10
model
analytical representation or quantification of a real system and the ways in which phenomena occur
within that system, used to predict or assess the behaviour of the real system under specified (often
hypothetical) conditions
[SOURCE: IAEA Safety Standard No. RS-G-1.8]
3.11
monitoring
measurement of dose, dose rate or activity for reasons relating to the assessment or control of exposure
to radiation or exposure due to radioactive substances, and the interpretation of the results
[SOURCE: IAEA Safety Glossary Terminology used in Nuclear Safety and Radiation Protection – 2018
Edition]
3.12
planned exposure situations
situation of exposure that arises from the planned operation of a source or from a planned activity that
results in an exposure due to a source
[SOURCE: IAEA Safety Glossary Terminology used in Nuclear Safety and Radiation Protection – 2018
Edition]
3.13
practice
human activity that introduces additional sources of exposure or exposure pathways or extends
exposure to additional people or modifies the network of exposure pathways from existing sources,
so as to increase the exposure or the likelihood of exposure of people or the number of people exposed
[SOURCE: IAEA Safety Standard No. RS–G–1.8]
3.14
quality assurance
planned and systematic actions necessary to provide adequate confidence that an item, process or
service satisfy given requirements for quality, for example, those specified in the license
[SOURCE: IAEA Safety Standard No. RS-G-1.8]
3.15
radioactive discharges
radioactive substances arising from a source (3.22) within a practice (3.13) which are discharged
as gases, aerosols, liquids or solids to the environment, generally with the purpose of dilution and
dispersion or disposal
[SOURCE: IAEA Safety Standard No. RS-G-1.8]
3.16
representative person
individual receiving a dose that is representative of the doses to the more highly exposed individuals in
the population
[SOURCE: ICRP Publication 101a. Annuals of the ICRP, 2006]
3.17
risk
combination of the probability of occurrence of harm and the severity of that harm
Note 1 to entry: The probability of occurrence includes the exposure to a hazardous situation, the occurrence of a
hazardous event and the possibility to avoid or limit the harm.
3.18
risk assessment
overall process comprising a risk analysis and a risk evaluation
3.19
screening
type of analysis aimed at eliminating from further consideration factors that are less significant for
protection or safety, in order to concentrate on the more significant factors
3.20
site
defined area, in this context often local target area
3.21
soil
surface layer of the Earth’s crust composed of mineral particles, including organic matter
3.22
source
anything that may cause radiation exposure, such as by emitting ionization or radiation or by relating
radioactive substances or materials, and can be treated as a single entry for protection and safety
purposes
Note 1 to entry: For example, materials emitting radon are sources in the environment, a sterilization gamma
irradiation unit is a source for the practice (3.13) of radiation preservation of food, an X ray unit may be a source for
the practice (3.13) of radiodiagnosis; a nuclear power plant is part of the practice (3.13) of generating electricity
by nuclear fission, and may be regarded as a source (e.g. with respect to discharges to the environment) or as
a collection of sources (e.g. for occupational radiation protection purposes). A complex or multiple installation
situated at one location or site may, as appropriate, be considered a single source for the purposes of application
of safety standards.
[SOURCE: IAEA Safety Standard No. RS-G-1.8]
3.23
surface soil
upper part of a natural soil, generally dark-coloured and with a higher content of organic substances
and nutrient when compared to the subsoil below
3.24
surface water
lakes, ponds, impounding reservoirs, springs, flowing (streaming) waters, estuaries, wetlands, inlets,
canals, oceans within the relevant territorial limits, and all other bodies of water, natural or artificial,
inland or coastal, fresh or salt
4 © ISO 2021 – All rights reserved

4 Symbols
a
At At +1  average activity concentration in air a of a radionuclide r during a year from t +1
() ()
r r 0
-3
in Bq·m
E annual effective dose in Sv
E annual effective dose of representative individual due to external exposure in Sv
ext
E committed effective dose of representative individual due to ingestion in Sv
ing
E committed effective dose of representative individual due to inhalation in Sv
inh
E an external exposure of airborne radionuclides in air
ext, air
E an external exposure of airborne radionuclides deposited on soil surface
ext, soil
E (t ) age dependent committed equivalent dose in tissue or organ, T, due to the inhalation
inh, T 1
of air during a year t ;
-1
g
age dependent committed effective dose coefficient from radionuclide, r, by ingestion in Sv·Bq
ing,r
-1
g
age dependent committed effective dose coefficient from radionuclide, r, by inhalation in Sv·Bq
inh,r
age dependent committed equivalent dose coefficient in tissue or organ, T, from radionuclide,
g
ing,rT,
-1
r, by ingestion in Sv·Bq
age dependent committed equivalent dose coefficient in tissue or organ, T, from radionuclide,
g
inh,rT,
-1
r, by inhalation in Sv·Bq
* -1

annual average ambient gamma dose-equivalent rate at 10 mm depth in Sv·h
Ht()10,
H committed equivalent dose in tissue or organ, T, in Sv
T, ext
H committed equivalent dose in tissue or organ, T, from ingestion in Sv
T, ing
H committed equivalent dose in tissue or organ, T, from inhalation in Sv
T, inh
r a given radionuclide part of a dose assessment
3 -1

age dependent breathing rate during a year in m ·year
V
w tissue or organ weight factor
T
5 Principle
Radioactivity is a natural phenomenon common to every part of our environment and we are
continuously exposed to these natural sources of radiation. Radiation and radioactive substances have
many applications, ranging from power generation to uses in medicine, industry and agriculture. The
radiation health risks to workers and the public and the impact on the environment that may arise from
these applications are assessed and, when necessary, controlled.
The aim of the health risk assessment of radioactive releases (authorized or accidental) from a nuclear
installation into the environment is to estimate the potential health consequences of human exposure
to radiation. The impact could be local, regional or worldwide, and can result from existing, planned or
nuclear emergency exposures. These assessments are performed to identify the needs and priorities
to ensure public health protection and to inform national authorities (decision makers) and the public.
Health risk assessment requires an estimation of radiation doses to the public that usually cannot
be measured directly. Therefore, for the purpose of protection of the public health, it is necessary
to characterise an individual, either hypothetical or specific. This individual is defined as the
‘representative person’.
In the case of prospective assessment, for estimating the impact of future liquid or gaseous discharges
from a particular emitter such as a nuclear facility, national regulations generally require dose
calculations to be carried out, based on the maximal foreseen quantities of radionuclides to be released
and considering conservative but realistic assumptions for determining the resulting quantities of
radionuclides in different compartments of the environment and then for calculating the effective dose
received by the representative person.
Complementarily to this approach, once the aforementioned facility is in operation, measurements
of the real activity concentrations of radionuclides in different compartments of the environment
can be carried out so as to check that they remain below those that were expected during the initial
assessment, and the dose assessment of the facility can be calculated as it relates to actual liquid
and gaseous discharges of the facility. In addition, radioactivity measurements in all the affected
compartments of the environment can help to confirm or to acquire useful information on mechanisms
of transfer of radionuclides in the environment, which is essential for enhancing robustness or for
building confidence in the dose assessment.
Finally, dose calculations can also be carried out directly from the results of radioactivity measurements
in the environment to determine the dose arising from exposure pathway.
Figure 1 — Annual dose assessment process for specified individual modified from ICRP
[ ]
Publ. 101 3
Dose assessment is a multistage process (see Figure 1) that follows the following stages:
— source identification and characterization, including data on the types and quantities of radionuclides
and radiations emitted;
— environmental characterization, such as meteorological condition, type of biota, agricultural
production, etc. and the activity concentration of radionuclides in environmental media and food
arising from the source under investigation;
6 © ISO 2021 – All rights reserved

— exposure scenario identification and characterization to combine environmental activity
concentration with habit data of the representative person (for example locations, ages, diets of the
exposed individuals or population);
— dose calculation using dose coefficients that either relate to activity concentration in air or soil to
external dose rates (external doses), or that convert a unit of intake of radionuclides through water
and food into dose (internal doses);
— effective dose calculation by summing up the contributions from external and internal dose.
An exposure assessment is the process by which the intensity, frequency and duration of human
exposure to a radionuclide are estimated. It is usually performed using one or more defined scenarios,
and on the basis of the data connected with a specific site.
Thus, depending on the scenario, different environmental pathways to a representative individual are
identified in order to determine the relevant activity concentration measurement of radionuclides in a
variety of environmental media.
The effective dose to the representative person may be calculated either following a deterministic or
[3]
a probabilistic approach, or a mixture of both approaches may be applied (see ICRP Pub101 ). The
method used depends on the situation, the capabilities and the data available. A brief description of
these approaches follows.
Deterministic and probabilistic methods may not necessarily yield mathematically equivalent results.
The simplest deterministic method for the assessment of compliance is a screening evaluation. This
method typically makes use of simplifying assumptions that lead to a very conservative estimate of
dose based on, for example, activity concentration of radionuclides at the point of discharge from the
source. Another simplifying assumption is to consider a single age group (e.g. adult) in estimating dose
to the public to compare with the dose constraints (ICRP, 2000). If the results of relatively conservative
screening assessments demonstrate that doses are well below the relevant dose constraint, there
may be no need for further detailed assessment of dose. A number of screening methods have been
[3]
developed and are available for application .
In another form of the deterministic method, a general assessment of the involved populations,
pathways, and radionuclides is made with the goal of identifying the group or groups receiving higher
doses using expert opinion, measurement data, or simple calculations. In some situations, people
receiving the higher doses are easily identified because site-specific exposure data are readily available
and habit information is known. In other situations, identifying these individuals is an iterative process
that considers key pathways of exposure and populations receiving doses from the source. The iterative
process usually indicates the areas that are likely to receive the greatest exposure from each pathway.
These areas should be investigated in more detail. Ultimately, an individual/group is identified that
is expected to receive the highest exposure taking all pathways into account. The mean dose to this
individual/group is compared with the dose constraint to determine compliance. This method is the
same as the critical group approach recommended previously by the ICRP.
The probabilistic method combines the distribution of values for parameters into a composite
distribution that presents a range of possible doses based on their probability of occurrence. The
distribution of calculated dose incorporates
a) the variability and uncertainty in the estimated environmental media activity concentration (i.e.
radionuclide activity concentration in air, water, soil) and food;
b) variability and uncertainty in the habit data (i.e. breathing rate, food and water ingestion rates,
time spent at various activities). As with the deterministic methods, identification of the exposed
population and the exposure scenarios of concern are likely to be an iterative process. However,
decision makers need guidance on how to determine compliance with the ICRP recommendations
when probabilistic methods are used.
A mixture of the deterministic and probabilistic methods is often used. One example of this is the use of
[9]
measurement data in an existing exposure situation to determine dose to individuals . In this case, a
distribution of doses is produced because of the variability and uncertainty of habit and measurement
data, and this distribution becomes the basis for determining compliance.
This document deals with the environmental monitoring stage on the activity concentration
measurement of radionuclides in environmental media and includes the elements of the pathway
exposure to assess either the total exposure of a given representative individual at risk, or the additional
exposure from a given source or activity.
Characterization of sites with respect to external and internal exposure pathways is described in
Clause 6, description of the environmental monitoring is given in Clause 7 where reference to other
relevant ISO documents is also made and guidance to assess the uncertainty to dose assessment result
is given in Clause 11.
6 Assessing and monitoring human exposure
For a representative assessment of the dose in order to highlight the possible effects on human health,
an analysis of the exposure routes is a prerequisite. For this purpose, the current and planned use of
the environment of the site is included in the assessment, as it defines which exposure pathways to the
representative individual are relevant. If a new use is planned, a renewed assessment should be carried
out. Realistic, average or worst-case scenario exposures can be defined and depending on the purpose
of the exposure assessment, the data needed for the assessment differ depending of the scenario chosen.
Even when representative individuals are not directly exposed to direct radiation, exposure
assessments need to consider the various ways by which indirect exposure might occur, and their
significance, see Figure 2.
Figure 2 — Possible pathways of exposure for members of the public as a result of discharges of
[9]
radioactive material to the environment
8 © ISO 2021 – All rights reserved

Two main categories of exposure pathway are defined: external exposure pathway when the source
of exposure remains outside the body and internal exposure pathways when the source of exposure is
incorporated into the body. The importance of the various exposure pathways depends on:
a) The radiological properties of the material released (e.g. gamma emitters, beta emitters or alpha
emitters; physical half-life);
b) The physical (e.g. gas, liquid or solid) and chemical (e.g. organic or inorganic form, oxidation state,
speciation, etc.) properties of the material and its migration characteristics;
c) The dispersal mechanism and factors affecting it (e.g. stack height, meteorological conditions, etc.)
and environmental characteristics (e.g. climate, type of biota, agricultural production, etc.);
d) The locations, ages, diets and habits of the exposed individuals or population.
e) The radionuclide is different in its behaviour in the environment and health impact on humans
depending on its chemical form or compound. The health risk depends on both the activity
concentration of a radionuclide and the duration and the route of exposure (skin contact, inhalation,
ingestion, etc.). For this reason, analysis of the changes that the radionuclide undergoes as a result
of these transformations and phase transfer processes prior to exposure is an important part of
exposure assessment.
To identify the media that have to be sampled and tested for their activity concentration, it is important
that the appropriate sampling strategy and measurement can be applied to assess the dose to an
individual.
Thus the assessment of the annual effective dose E(t ) for a year t to a representative individual
1 1
requires the quantification of the contributions due to external exposure E and the internal
ext
exposure due to ingestion and inhalation of radionuclides, E and E respectively. According to ICRP
ing inh
[3]
publications such an evaluation has to be performed for the different tissues, T, taking into account
the age dependence of exposure and of dose factors and the tissue weighing factors, w , see Formula 1:
T
Et()=+EE +=Ew ⋅+HH +H (1)
()
1 exting inhe∑ TT,,xt TTingi, nh
T
One important purpose of environmental monitoring is to provide the data that permit the analysis and
the evaluation of the three terms of the formula to compute the human radiation exposure:
EE,, E .
exting inh
Thus, the quality of the environmental input data that characterize the parameters of the mathematical
formulae used to compute the effective dose are essential.
For this purpose, programs for monitoring radionuclides in the environment focus on pathways of
human exposure, see Table 1. An exposure pathway defines routes from a source of radionuclides and/or
radiation to a target: a representative person or a population through the different environmental media.
Monitoring programs of the environment usually integrate the sampling of plant or animal species that
are not part of the diet of the exposed individuals or population. They are selected for their ability to
accumulate radionuclides at higher activity concentrations than those usually found in the atmosphere,
soil or water compartment where they live. These bioindicators are considered as "sentinel" organisms
to detect minor radioa
...