IEC 60695-7-2:2021

IEC 60695-7-2 ®
Edition 2.0 2021-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
HORIZONTAL PUBLICATION
PUBLICATION HORIZONTALE
Fire hazard testing –
Part 7-2: Toxicity of fire effluent – Summary and relevance of test methods

Essais relatifs aux risques du feu –
Partie 7-2: Toxicité des effluents du feu – Résumé et pertinence des méthodes
d'essai
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IEC 60695-7-2 ®
Edition 2.0 2021-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
HORIZONTAL PUBLICATION
PUBLICATION HORIZONTALE
Fire hazard testing –
Part 7-2: Toxicity of fire effluent – Summary and relevance of test methods

Essais relatifs aux risques du feu –

Partie 7-2: Toxicité des effluents du feu – Résumé et pertinence des méthodes

d'essai
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.220.40; 29.020 ISBN 978-2-8322-1003-1

– 2 – IEC 60695-7-2:2021 © IEC 2021
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Role of small-scale toxicity tests . 13
4.1 General . 13
4.2 Toxic potency . 13
4.3 Toxic hazard, exposure dose and fractional effective dose (FED) . 14
4.4 Fractional effective concentration (FEC) . 14
4.5 Generic toxic potencies . 14
5 General aspects of small-scale toxicity tests . 15
5.1 General . 15
5.2 Physical fire models . 15
5.3 Fire stages in a compartment fire . 16
5.4 Methods of analysis . 16
5.4.1 General . 16
5.4.2 Chemical analysis based methods . 19
5.4.3 Methods based on animal exposure . 19
6 Summary of published chemical analysis based test methods . 19
6.1 General . 19
6.2 UK Ministry of Defence – DEF STAN 02-713 . 19
6.2.1 Summary . 19
6.2.2 Purpose and principle . 20
6.2.3 Test specimen . 20
6.2.4 Test method . 20
6.2.5 Repeatability and reproducibility . 21
6.2.6 Relevance of test data and special observations. 21
6.3 Airbus industry . 22
6.3.1 Summary . 22
6.3.2 Purpose and principle . 22
6.3.3 Test specimen . 22
6.3.4 Test method . 22
6.3.5 Repeatability and reproducibility . 22
6.3.6 Relevance of test data and special observations. 23
6.4 Comitato Elettrotecnico Italiano (CEI) . 23
6.4.1 Summary . 23
6.4.2 Purpose and principle . 23
6.4.3 Test specimen . 23
6.4.4 Test method . 23
6.4.5 Repeatability and reproducibility . 23
6.4.6 Relevance of test data and special observations. 23
6.5 Norme Française (NF) . 24
6.5.1 Summary . 24
6.5.2 Purpose and principle . 24
6.5.3 Test specimen . 24

6.5.4 Test method . 24
6.5.5 Repeatability and reproducibility . 24
6.5.6 Relevance of test data and special observations. 24
6.6 ISO test methods . 25
6.6.1 ISO/TS 19021 . 25
6.6.2 ISO/TS 19700 . 26
6.7 International Maritime Organization (IMO) . 27
6.7.1 Summary . 27
6.7.2 Purpose and principle . 27
6.7.3 Test specimen . 27
6.7.4 Test method . 27
6.7.5 Repeatability and reproducibility . 28
6.7.6 Relevance of test data and special observations. 28
6.8 Toxicity test for rolling stock cables. 28
6.8.1 Summary . 28
6.8.2 Purpose and principle . 29
6.8.3 Test specimen . 29
6.8.4 Test method . 29
6.8.5 Repeatability and reproducibility . 29
6.8.6 Relevance of test data and special observations. 30
6.9 Toxicity test of materials and components (other than cables) used in railway
applications . 30
6.9.1 Summary . 30
6.9.2 Purpose and principle . 30
6.9.3 Test specimen . 30
6.9.4 Test method . 30
6.9.5 Repeatability and reproducibility . 31
6.9.6 Relevance of test data and special observations. 31
7 Summary of published test methods relating to animal exposure . 31
7.1 General . 31
7.2 Deutsches Institut für Normung, DIN 53436 . 31
7.2.1 Summary . 31
7.2.2 Purpose and principle . 31
7.2.3 Test specimen . 31
7.2.4 Test method . 32
7.2.5 Repeatability and reproducibility . 32
7.2.6 Relevance of test data and special observations. 32
7.3 National Bureau of Standards (NBS) . 33
7.3.1 Summary . 33
7.3.2 Purpose and principle . 33
7.3.3 Test specimen . 33
7.3.4 Test method . 33
7.3.5 Repeatability and reproducibility . 33
7.3.6 Relevance of test data and special observations. 34
7.3.7 Reference documents . 34
7.4 National Institute of Standards and Technology, NIST Radiant furnace . 34
7.4.1 Summary . 34
7.4.2 Purpose and principle . 34
7.4.3 Test specimen . 35

– 4 – IEC 60695-7-2:2021 © IEC 2021
7.4.4 Test method . 35
7.4.5 Repeatability and reproducibility . 35
7.4.6 Relevance of test data and special observations. 35
7.4.7 Reference documents . 36
7.5 University of Pittsburgh, Upitt Box furnace . 36
7.5.1 Summary . 36
7.5.2 Purpose and principle . 36
7.5.3 Test specimen . 36
7.5.4 Test method . 36
7.5.5 Repeatability and reproducibility . 37
7.5.6 Relevance of test data and special observations. 37
7.5.7 Reference documents . 37
7.6 Japanese fire toxicity test for building components . 37
7.6.1 Summary . 37
7.6.2 Purpose and principle . 37
7.6.3 Test specimen . 37
7.6.4 Test method . 38
7.6.5 Repeatability and reproducibility . 38
7.6.6 Relevance of test data and special observations. 38
8 Overview of methods and relevance of data . 38
Bibliography . 41

Figure 1 – Different phases in the development of a fire within a compartment . 16

Table 1 – Characteristics of fire types (ISO 19706) . 18
Table 2 – C values for various gases . 21
f
Table 3 – Volume fraction limits for gas components . 22
Table 4 – Decomposition conditions . 26
The results are expressed as gas volume fractions. Maximum permitted values are
given below (see Table 5 – Volume fraction limits for gas component . 28
Table 5 – Volume fraction limits for gas component . 28
Table 6 – CC values taken from EN 50305 . 29
z
Table 7 – Reference concentrations of the gas components . 31
Table 8 – Overview of toxicity test methods . 39
Table 9 – Overview of toxicity test methods (continued, with comments) . 40

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIRE HAZARD TESTING –
Part 7-2: Toxicity of fire effluent –
Summary and relevance of test methods

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60695-7-2 has been prepared by IEC technical committee 89: Fire
hazard testing.
This second edition cancels and replaces the first edition published in 2011. This edition
constitutes a technical revision.
The main changes with respect to the previous edition are listed below:
– New text in the introduction;
– New text in the scope;
– Clause 2 has been updated;
– Many terms and definitions in Clause 3 reproduced from ISO 13943 have been deleted.
Other terms and definitions have been added.
– New text in Subclauses 4.3 and 4.4;
– New text in Subclause 6.1;
– 6 – IEC 60695-7-2:2021 © IEC 2021
– References to IEC 60695-7-50 and -51 (now withdrawn) have been removed;
– Reference to DEF STAN 07-247 has been added;
– Details of ISO/TS 19021 have been added;
– Details of EN 17084 have been added;
– New text added concerning ISO/TS 19700;
– New text added concerning the IMO FTP toxicity test;
– New Subclause 7.1 has been added;
– The Annex in Edition1 has been replaced by new Clause 8;
– The bibliography has been updated.
The text of this International Standard is based on the following documents:
Draft Report on voting
89/1489/CDV 89/1508/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
It has the status of a basic safety publication in accordance with IEC Guide 104.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
A list of all the parts in the 60695 series, under the general title Fire hazard testing, can be
found on the IEC website.
IEC 60695-7 consists of the following parts:
Part 7-1: Toxicity of fire effluent – General guidance
Part 7-2: Toxicity of fire effluent – Summary and relevance of test methods
Part 7-3: Toxicity of fire effluent – Use and interpretation of test results
In this document the following print types are used:
– Words in italics in the text are defined in Clause 3.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
INTRODUCTION
In the design of an electrotechnical product, the risk of fire and the potential hazards associated
with fire need to be considered. In this respect the objective of component, circuit and
equipment design, as well as the choice of materials, is to reduce the risk of fire to a tolerable
level even in the event of reasonably foreseeable (mis)use, malfunction or failure.
IEC 60695-1-10, IEC 60695-1-11 [1] , and IEC 60695-1-12 [2] provide guidance on how this is
to be accomplished.
Fires involving electrotechnical products can also be initiated from external non-electrical
sources. Considerations of this nature are dealt with in an overall fire hazard assessment.
The aim of the IEC 60695 series of standards is to save lives and property by reducing the
number of fires or reducing the consequences of the fire. This can be accomplished by:
• trying to prevent ignition caused by an electrically energised component part and, in the
event of ignition, to confine any resulting fire within the bounds of the enclosure of the
electrotechnical product;
• trying to minimise flame spread beyond the product’s enclosure and to minimise the harmful
effects of fire effluents including heat, smoke, and toxic or corrosive combustion products.
Electrotechnical products, primarily as the objects of a fire, may contribute to the fire hazard
due to the release of toxic effluent, which may be a significant contributing factor to the overall
fire hazard.
The IEC 60695-7 series provides guidance to IEC product committees on the adoption and
implementation of the recommendations of ISO for the minimization of toxic hazard from fires
involving electrotechnical products.This part of IEC 60695-7 describes fire effluent toxicity test
methods in common use to assess electrotechnical products or materials used in
electrotechnical products.
IEC product committees incorporating requirements for the assessment of toxic hazard from
fire in product standards should note that toxic potency and other measurements of toxicity
which are described in this part of IEC 60695 should not be used directly in product
specifications. Data from toxic potency test methods should only be used as part of a toxic
hazard assessment, in conjunction with other product-based reaction to fire data such as mass
loss rate.
___________
Numbers in square brackets refer to the bibliography.

– 8 – IEC 60695-7-2:2021 © IEC 2021
FIRE HAZARD TESTING –
Part 7-2: Toxicity of fire effluent –
Summary and relevance of test methods

1 Scope
This part of IEC 60695-7 gives a brief summary of the test methods that are in common use in
the assessment of the toxicity of fire effluent. It includes special observations on their relevance
to real fire scenarios and gives recommendations on their use.
It advises which tests provide toxic potency data that are relevant to real fire scenarios, and
which are suitable for use in fire hazard assessment and fire safety engineering.
The list of test methods is not to be considered exhaustive.
This summary cannot be used in place of published standards which are the only valid reference
documents.
This basic safety publication is intended for use by technical committees in the preparation of
standards in accordance with the principles laid down in IEC Guide 104 and ISO/IEC Guide 51.
One of the responsibilities of a technical committee is, wherever applicable, to make use of
basic safety publications in the preparation of its publications. The requirements, test methods
or test conditions of this basic safety publication will not apply unless specifically referred to or
included in the relevant publications.
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.
IEC 60695-1-10, Fire hazard testing - Part 1-10: Guidance for assessing the fire hazard of
electrotechnical products - General guidelines
IEC 60695-7-1, Fire hazard testing - Part 7-1: Toxicity of fire effluent - General guidance
IEC 60695-7-3, Fire hazard testing - Part 7-3: Toxicity of fire effluent - Use and interpretation
of test results
IEC GUIDE 104, The preparation of safety publications and the use of basic safety publications
and group safety publications
ISO/IEC Guide 51, Safety aspects – Guidelines for their inclusion in standards
ISO 13943:2017, Fire safety – Vocabulary
ISO 13344, Estimation of the lethal toxic potency of fire effluents

ISO 13571:2007, Life-threatening components of fire – Guidelines for the estimation of time
available for escape using fire data
ISO/TR 16312-2, Guidance for assessing the validity of physical fire models for obtaining fire
effluent toxicity data for fire hazard and risk assessment – Part 2: Evaluation of individual
physical fire models
ISO 19706, Guidelines for assessing the fire threat to people
ISO 29903:2012, Guidance for comparison of toxic gas data between different physical fire
models and scales
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13943:2017, some of
which are reproduced below for the user's convenience, and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
acute toxicity
toxicity that causes rapidly occurring toxic effects
Note 1 to entry: Compare with the term toxic potency (3.16).
[ISO 13943:2017, definition 3.8]
3.2
asphyxiant
toxicant (3.17) that causes hypoxia, which can result in central nervous system depression or
cardiovascular effects
Note 1 to entry: Loss of consciousness and ultimately death may occur.
[ISO 13943:2017, definition 3.23]
3.3
concentration
mass of a dispersed or dissolved material in a given volume
−3
Note 1 to entry: For a fire effluent the typical unit is g⋅ m .
Note 2 to entry: For toxic gas, concentration is usually expressed as a volume fraction (3.18) at T = 298 K and
3 3 −6
P = 1 atm, with typical units of µL/L (= cm /m = 10 ).
Note 3 to entry: The concentration of a gas at a temperature, T, and a pressure, P, can be calculated from its
volume fraction (assuming ideal gas behaviour) by multiplying the volume fraction by the density of the gas at that
temperature and pressure.
Note 4 to entry: Pascal (Pa) is the SI unit for pressure; however, atmosphere (atm) is typically used in this context,
where 1 atm = 101,3 kPa.
[ISO 13943:2017, definition 3.62]

– 10 – IEC 60695-7-2:2021 © IEC 2021
3.4
effective concentration 50
EC
concentration (3.3) of a toxic gas or fire effluent, statistically calculated from concentration-
response data, that causes a specified effect in 50 % of a population of a given species within
a specified exposure time and post-exposure time
Note 1 to entry: Compare with the term IC (ISO 13943:2017, 3.211).
−3
Note 2 to entry: For fire effluent, the typical unit is g × m .
Note 3 to entry: For toxic gas, the typical unit is µL/L (T = 298 K and P = 1 atm); see volume fraction (3.18).
Note 4 to entry: The observed effect is usually a behavioural response, incapacitation (3.8), or death. The EC for
incapacitation is termed the IC . The EC for lethality is termed the LC (3.11).
50 50 50
3.5
exposure dose
measure of the maximum amount of a toxic gas or fire effluent that is available for inhalation,
calculated by integration of the area under a concentration-time curve
−3
Note 1 to entry: For fire effluent, the typical unit is g × min × m .
−1
Note 2 to entry: For toxic gas, the typical unit is µL × min × L (T = 298 K and P = 1 atm); see volume fraction (3.18).
[ISO 13943:2017, definition 3.107]
3.6
fractional effective concentration
FEC
ratio of the concentration (3.3) of an irritant (3.9) to that concentration expected to produce a
specified effect on an exposed subject of average susceptibility
Note 1 to entry: Compare with the term F factor (ISO 13943:2017, 3.112).
Note 2 to entry: As a concept, FEC may refer to any effect, including incapacitation (3.8), lethality or other
endpoints.
Note 3 to entry: When not used with reference to a specific irritant, the term FEC represents the summation of FEC
values for all irritants in a fire-generated atmosphere.
Note 4 to entry: The FEC is dimensionless.
[ISO 13943:2017, definition 3.187]
3.7
fractional effective dose
FED
ratio of the exposure dose (3.5) for an asphyxiant (3.2) to that exposure dose of the asphyxiant
expected to produce a specified effect on an exposed subject of average susceptibility
Note 1 to entry: As a concept, FED may refer to any effect, including incapacitation (3.8), lethality or other
endpoints.
Note 2 to entry: When not used with reference to a specific asphyxiant, the term FED represents the summation of
FED values for all asphyxiants in a combustion atmosphere.
Note 3 to entry: The FED is dimensionless.
[ISO 13943:2017, definition 3.188]
3.8
incapacitation
state of physical inability to accomplish a specific task

Note 1 to entry: An example of a specific task is to accomplish escape from a fire.
[ISO 13943:2017, definition 3.225]
3.9
irritant, noun
gas or aerosol that stimulates nerve receptors in the eyes, nose,
mouth, throat and respiratory tract, causing varying degrees of discomfort and pain with the
initiation of numerous physiological defence responses
Note 1 to entry: Physiological defence responses include reflex eye closure, tear production, coughing, and
bronchoconstriction.
[ISO 13943:2017, definition 3.237]
3.10
irritant, noun
gas or aerosol that stimulates nerve receptors in the lower respiratory tract, which
may result in breathing discomfort
Note 1 to entry: Examples of breathing discomfort are dyspnoea and an increase in respiratory rate. In severe
cases, pneumonitis or pulmonary oedema (which may be fatal) may occur some hours after exposure.
[ISO 13943:2017, definition 3.238]
3.11
lethal concentration 50
LC
concentration (3.3) of a toxic gas or fire effluent, statistically calculated from concentration-
response data, that causes death of 50 % of a population of a given species within a specified
exposure time and post-exposure time
Note 1 to entry: Compare with the term effective concentration 50 (3.4).
−3
Note 2 to entry: For fire effluent, the typical unit is g × m .
Note 3 to entry: For toxic gas, the typical unit is µL/L (T = 25 °C and P = 1 atm; see volume fraction (3.18).
[ISO 13943:2017, definition 3.241]
3.12
lethal exposure dose 50
LCt
product of LC (3.11) and the exposure time over which it was determined
Note 1 to entry: Compare with the terms concentration (3.3), effective exposure dose 50 (ISO 13943:2017, 3.87),
exposure dose (3.5) and lethal exposure time 50 (ISO 13943:2017, 3.243).
Note 2 to entry: LCt is a measure of lethal toxic potency (3.13).
–3
Note 3 to entry: For fire effluent, the typical unit is g⋅min⋅m .
−1
Note 4 to entry: For toxic gas, the typical unit is µL⋅min⋅L ) (T = 25 °C and P = 1 atm); see volume fraction (3.18).
[ISO 13943:2017, definition 3.242]
3.13
lethal toxic potency
toxic potency (3.16) where the specific toxic effect is death

– 12 – IEC 60695-7-2:2021 © IEC 2021
Note 1 to entry: Compare with the terms lethal concentration 50 (LC ) (3.11) and lethal exposure dose 50
(LCt ) (3.12).
[ISO 13943:2017, definition 3.244]
3.14
mass loss concentration
〈closed system〉 mass of the test specimen consumed during combustion divided by the test
chamber volume
–3
Note 1 to entry: The typical unit is g × m .
[ISO 13943:2017, definition 3.262]
3.15
mass loss concentration
〈open system〉 mass of the test specimen consumed during combustion divided by the total
volume of air passed through the test apparatus
Note 1 to entry: The definition assumes that the mass is dispersed in the air flow uniformly over time.
−3
Note 2 to entry: The typical unit is g × m .
[ISO 13943:2017, definition 3.263]
3.16
toxic potency
measure of the amount of toxicant (3.17) required to elicit a specific toxic effect
Note 1 to entry: Compare with the terms effective exposure dose 50 (ISO 13943:2017, 3.87) and lethal exposure
dose 50 (3.12).
Note 2 to entry: A small value of toxic potency corresponds to a high toxicity, and vice versa.
ISO 13943:2017, definition 3.402
3.17
toxicant
toxin
toxic substance
ISO 13943:2017, definition 3.404
3.18
volume fraction
〈gas in a gas mixture〉 ratio of the volume that the gas alone would occupy at a defined
temperature and pressure, to the volume occupied by the gas mixture at the same temperature
and pressure
Note 1 to entry: The concentration (3.3) of a gas at a temperature, T, and a pressure, P, can be calculated from its
volume fraction (assuming ideal gas behaviour) by multiplying the volume fraction by the density of the gas at that
temperature and pressure.
Note 2 to entry: Unless stated otherwise, a temperature of 298 K and a pressure of 1 atm are assumed.
3 3 –6
Note 3 to entry: The volume fraction is dimensionless and is usually expressed in terms of µL/L (= cm /m = 10 ),
or as a percentage.
ISO 13943:2017, definition 3.421

3.19
volume yield
volume, at 298 K and 1 atm, of a component of fire effluent divided by the mass loss of the test
specimen associated with the production of that volume
3 −1
Note 1 to entry: The typical unit is m × g .
ISO 13943:2017, definition 3.422
4 Role of small-scale toxicity tests
4.1 General
Small-scale toxicity tests, and toxic potency tests in particular, serve a very specific purpose –
to generate data to be used in toxic hazard assessments, fire hazard assessments, or fire‑safety
engineering calculations.
These tests are often wrongly interpreted as providing data which give a direct indication of the
toxicity or toxic hazard associated with a material or product. Such interpretations are invalid
and are contrary to the guidance given in ISO 19706 and IEC 60695-7-1, and are likely to lead
to incorrect assumptions about the contribution of a given material or product to toxic hazard.
Therefore, the data from small-scale toxicity tests should not be used directly in product
specifications, or to imply in isolation, any level of toxic hazard.
Data from toxic potency test methods should only be used as part of a toxic hazard assessment
in conjunction with other product based reaction to fire data such as mass loss rate.
Guidance for the comparison of toxic gas data between different physical fire models and scales
is given in ISO 29903:2012.
4.2 Toxic potency
The term toxic potency is a specific technical term in fire science. It is the measure of the
amount of toxicant required to elicit a specific toxic effect. One specific toxic potency that is
commonly used is the exposure dose that causes the death of 50 % of exposed organisms. This
is known as the LCt (lethal exposure dose 50).
th
The exposure dose of the i toxic component, [D] , in a mixture of toxic components, is defined
i
by the following equation:
[D] = C dt = X m dt = X D
i i i m
i
∫ ∫
V
th
or, if the volume fraction of the i toxic component is constant over time,
[D] = C × t
i
i
where
th
C is the volume fraction of the i toxic component;
i
th
X is the volume yield of the i toxic component from a toxic potency test;
i
D is the mass loss concentration integral, which is the integral of the mass lost over the
m
exposure time, t, divided by the volume of the fire effluent;

– 14 – IEC 60695-7-2:2021 © IEC 2021
m is the mass of the test specimen lost during the time of exposure;
t is the exposure time, and
V is the volume into which the fire effluent is dispersed.
In both cases the exposure dose has units of volume fraction × time, e.g. min.
In some cases, m/V, known as mass loss concentration, is used instead of the volume fraction,
−3
in which case the exposure dose has units of concentration × time, e.g. g × min × m .
−3
Suppose that a 30 min exposure to a mass loss concentration of 20 g⋅m causes the defined
−3
effect, then the toxic potency of the material is 600 g × min × m . This means that, for example,
−3
an exposure of 10 min to a mass loss concentration of 60 g × m is assumed to cause the
−3
defined effect. Similarly, an exposure of 20 min to a mass loss concentration of 30 g × m is
also assumed to cause the same defined effect.
The toxic potency of the fire effluent
...