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Normalization in EDIP97 and EDIP2003:
Updated European inventory for 2004 and
guidance towards a consistent use in practice
Article in The International Journal of Life Cycle Assessment · June 2011
DOI: 10.1007/s11367-011-0278-6
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Int J Life Cycle Assess (2011) 16:401–409
DOI 10.1007/s11367-011-0278-6
LIFE CYCLE IMPACT ASSESSMENT
Normalization in EDIP97 and EDIP2003: updated European
inventory for 2004 and guidance towards a consistent
use in practice
Alexis Laurent & Stig Irving Olsen &
Michael Zwicky Hauschild
Received: 30 November 2010 / Accepted: 10 March 2011 / Published online: 5 April 2011
# Springer-Verlag 2011
Abstract
Purpose When performing a life cycle assessment (LCA),
the LCA practitioner faces the need to express the
characterized results in a form suitable for the final
interpretation. This can be done using normalization against
some common reference impact—the normalization references—which require regular updates. The study presents
updated sets of normalization inventories, normalization
references for the EDIP97/EDIP2003 methodology and
guidance on their consistent use in practice.
Materials and methods The base year of the inventory is
2004; the geographical scope for the non-global impacts is
limited to Europe. The emission inventory was collected
from different publicly available databases and monitoring
bodies. Where necessary, gaps were filled using extrapolations. A new approach for inventorizing specific groups of
substances—non-methane volatile organic compounds and
pesticides—was also developed. The resulting inventory was
combined with the most updated sets of characterization
factors for each impact category in the EDIP methodologies.
Results and discussion Normalization references are provided for global and non-global impact categories for the
year 2004, and causes of variations compared to previous
versions are identified. For the non-toxic impact categories,
they mainly reflect demographic evolution or change in
emission intensities. For the toxic impact categories, they
are strongly dependent on improvements in the characterization models as well as on the inventory analysis.
Differentiation of substance groups into individual substance emissions is an important source, which leads to
identification of inconsistencies in the current practice and
guidance to ensure compatibility between LCI and LCIA.
Uncertainties are not quantified but are mainly expected to
lie in the toxic substance inventories, which are known not
to encompass all potentially harmful chemicals released in
Europe, e.g. omitting some toxic metals.
Conclusions The present study provides the most updated set
of publicly available normalization references for the EDIP
methodology and emission inventories for Europe that may
also serve for the calculation of normalization references for
other impact categories. It is believed to be the best estimate
available for Europe and is thus recommended for use along
with the guidance provided in this study.
Keywords EDIP . European inventory . LCI . LCIA . Life
cycle inventory . Normalisation . Normalisation reference
1 Introduction
Responsible editor: Berlan Rodríguez-Perez
Electronic supplementary material The online version of this article
(doi:10.1007/s11367-011-0278-6) contains supplementary material,
which is available to authorized users.
A. Laurent (*) : S. I. Olsen : M. Z. Hauschild
Section for Quantitative Sustainability Assessment (QSA),
Department of Management Engineering,
Technical University of Denmark (DTU),
Produktionstorvet 426,
2800 Kgs, Lyngby, Denmark
e-mail: alau@man.dtu.dk
With its translation of the product system's environmental
flows from the life cycle inventory phase (LCI) into scores
that represent their impacts on environment, life cycle
impact assessment (LCIA) is essential for the interpretation
of the results in relation to the questions posed in the goal
definition (Finnveden et al. 2009). Being an optional step in
LCIA according to ISO14044:2006 (ISO 2006), normalization of the characterized results gives insight in the
relative magnitude of the characterized impacts by relating
402
them to a common reference situation and expressing them
in a unit common for all impact categories. The reference
situation is typically the background load from society's
total activities, either representing a region (e.g. world or
EU25+3 in ReCiPe or CML2001; Sleeswijk et al. 2008;
Guinée et al. 2002) or expressed per capita in a given
region (e.g. in EDIP or IMPACT2002+; Wenzel et al. 1997;
Stranddorf et al. 2005; Lautier et al. 2010). The normalization references are calculated by characterizing the
emission inventory for the reference situation in the same
way as the inventory for the product system is characterized, and the normalization is performed by dividing the
characterized results for the product system by the
normalization references. After normalization all impact
category results are expressed in the same unit, e.g. in the
EDIP case the person equivalent (PE), the number of average
annual per capita impacts caused by the product system.
The calculation of the normalization references requires
an inventory analysis for the background load, which in
itself can be as extensive as a product LCA. Typically, the
background load is quantified for a reference year, which
should be the same for all impact categories. For a given
region the background load may evolve significantly over
the years, e.g. because of regulations of chemicals or an
increase in pollutant releases. Together with the continuous
improvements in the characterization models, this requires
that updates of normalization references are performed
regularly in order for the LCA practitioner to base his/her
interpretation on consistent and reliable results.
While the normalization inventories (see ESM 1) can
also be used for calculating normalization references for
other LCIA methodologies, the main purpose of this study
is to provide an updated emission inventory in support of
calculating new normalization references for the Environmental Design of Industrial Products (EDIP) methodology,
which is a Danish LCA methodology originally developed
in the 90s (Wenzel et al. 1997; Hauschild and Wenzel 1998)
and revised in 2003 (Hauschild and Potting 2005).
Furthermore the purpose of the paper is to discuss the
causes of changes in the normalization references and the
main sources of uncertainty in the results.
2 Materials and methods
2.1 LCIA methodologies
The assessment of the impact categories is performed with
both the original EDIP97 (Wenzel et al. 1997) and the
EDIP2003 methodologies (Hauschild and Potting 2005;
Potting and Hauschild 2005), using the most updated sets
of characterization factors (LCA Center 2010). Compared
to the EDIP97 methodology, the EDIP2003 impact assess-
Int J Life Cycle Assess (2011) 16:401–409
ment includes a larger part of the impact pathway for the
non-global impact categories and supports both a sitegeneric and a site-dependent assessment on a per-country
level within Europe. Emphasis in EDIP2003 is put on
including the properties of the emission sources and the
receiving environment, which vary significantly within the
region. Typically impacts occurring in local areas are partly
caused by emissions outside those areas (e.g. dispersion of
airborne emissions), hence the need to adopt consistent
boundaries; EDIP2003 considers the whole continent of
Europe (Potting and Hauschild 2005).
In parallel, the traditional assessment of resource depletion
of EDIP97 was also adapted to enable the aggregation of the
results—commonly obtained per resource—into one single
score (similarly to any other impact category). Details of this
adaptation, which requires a new definition of characterization factors, are provided in ESM 2. The consequent
normalization reference of this new approach was calculated
using existing data for 2004 from the LCA Center (2010).
2.2 Inventory
The inventory study builds on previous works by Potting
and Hauschild (2005) and Stranddorf et al. (2005) to
establish a comprehensive inventory focusing on emissions
that occurred within Europe in 2004; 38 European
countries, representing a population of 719 million inhabitants out of the 729 million reported by UNSD (2010) for
Europe, were considered. Data quality and availability vary
significantly between substances or groups of substances.
Data collection for non-toxic impact categories benefits from
the fact that the impacts are caused by emissions of few
substances, which have been monitored and reported for
several years, at least in Europe. Consequently, consistent
databases are publicly available through reliable organizations
such as the EMEP Centre or EUROSTAT (see ESM 2).
In contrast, toxic impacts may be caused by thousands of
substances for which no well-proven systems of monitoring
and reporting exist. This issue has previously been
discussed (Finnveden et al. 2009; Sleeswijk et al. 2008),
and efforts are still on-going to mitigate it. An EU
regulation entered into force in 2006 with the aim to
establish a publicly available database of emissions of
potentially hazardous pollutants released to air, soil and
water from industrial facilities in Europe—the European
Pollutant Release and Transfer Register, E-PRTR (http://prtr.
ec.europa.eu/). Cross-checking with reports from authoritative organizations such as OSPAR or the EMEP Centre
revealed, however, that the database is not yet sufficiently
comprehensive to serve the purpose of this study (data not
shown). To fill the gaps in the emission inventory for the
toxic impacts, extrapolations thus had to be performed;
details can be found in ESM 2.
Int J Life Cycle Assess (2011) 16:401–409
Typically, non-methane volatile organic compounds
(NMVOCs) are inventorized as a group, and most impact
assessment methods provide one or a few generic characterization factors for the human toxicity or photochemical
ozone formation impact of the group as such (e.g. EDIP97,
CML). While being of minor importance to the photochemical ozone formation, the differentiation of NMVOCs
into single substances is highly relevant for the assessment
of their human toxicity impact—see Section 4.3. This
compelled us to differentiate emissions of NMVOCs into
the most important individual substances in this study. An
additional benefit of differentiating emissions of NMVOCs
lies in the minimization of the risk of double counting in
cases where some substances of central interest, such as
benzene, are reported as individual emissions alongside the
total NMVOC emissions.
For the inventory analysis of European pesticide emissions, the agricultural soil was considered to be part of the
technosphere. This means that only those fractions of the
applied active ingredients that cross the boundaries of the
field and reach the biosphere were included in the
inventory, i.e. depositions from the air due to volatilization
and wind drift from the field as well as leaching to
groundwater and run-off to freshwater ecosystems. Based
on estimates using the PestLCI model (Birkved and
Hauschild 2006), average fractions of 5% and 0.1% were
assumed for modelling direct airborne emissions and
waterborne emissions from the field, respectively. Also for
the pesticide use, a specification of the applied mixture into
active ingredients was performed, using extrapolations from
English and Danish pesticide application statistics combined with EUROSTAT reports (see details in ESM 2).
3 Results
The inventory for European normalization references for
emission year 2004 is shown in ESM 1 in aggregated form
for the whole of Europe. The EDIP97 and EDIP2003
normalization references are provided in Table 1. Where
applicable, the old normalization references are also shown
in Table 1 for comparison. The normalization references for
individual European countries can be viewed in ESM 1.
403
factors and (4) refinement in the inventory modelling such
as the extension of emission inventories or specification of
groups of substances.
While the normalization references for non-toxic impact
categories are typically affected by the first two causes—
see Section 4.1, changes in the normalization references for
the toxicity-related impact categories are mainly driven by
the last two causes—see Sections 4.2 and 4.3.
4.1 Influence of changes in emission and population
Contribution analyses have been performed to identify the
dominating contributors for each impact category (Table 2);
normalization references for the non-toxic impact categories are typically dominated by a few substances, which
have been well monitored for several years (see data
sources in ESM 2). Therefore, the inventories can be
assumed to be relatively complete. The changes observed in
Table 1 between the old set and the new set of
normalization references for the impact categories global
warming, ozone depletion, acidification, nutrient enrichment/eutrophication and photochemical ozone formation
thus tend to reflect actual changes of emissions and/or
demography.
The introduction of new potentially harmful chemicals
on the market or the regulation or phasing out of others are
possible causes of either the increase or decrease in the
normalization references. An example is provided by ozone
depletion with its normalization reference dropping by a
factor of 5 between 1994 and 2004 (cf. Table 1), and by a
factor of 15, when comparing with more recent figures
from 2008 (not shown here).
At the same time, changes in population figures within the
reference region can also affect the normalization references,
when they are expressed on an annual per capita basis as is the
case in EDIP. In the case of an increasing population, this
factor tends to lower the normalization reference. Taking the
impact category “global warming”, between 1994 and 2004,
emissions of greenhouse gases increased by 1.6%, while the
demographic growth was much higher, i.e. 15%, leading to an
overall decrease of the normalization reference, from 8.7 to
7.7 t-CO2eq/capita/year (data for 1994 are based on
Stranddorf et al. 2005).
4.2 Influence of characterization models
4 Causes of variations in normalization references
When updating normalization references, changes can
result from several causes: (1) change in the substance
emissions from the old to the new reference year, (2)
change in the size of the population within the reference
region, (3) improvements in the characterization models
and/or in their coverage of substances with characterization
For the toxic impact categories, it is updates of the
characterization models as well as changes in the substance
coverage that together with inventory choices discussed in
Section 4.3 constitute the main causes for the changes
observed in the normalization references in Table 1. This is
visible from the contribution analyses in Table 3. Taking
human toxicity via air (HTA) from both EDIP97 and
404
Int J Life Cycle Assess (2011) 16:401–409
Table 1 Normalization references for the 22 EDIP impact categories (emission year 2004)
Impact categories
Symbols
Method
Geographical
scope
Norm. ref.
(NR)
Old NR
(1994)
Unit
Global warming
Ozone depletion
Acidification
Nutrient enrichment
–N-equivalents
–P-equivalents
Photochemical ozone formation
(low-NOX)
Photochemical ozone formation
(high-NOX)
Acidification
Terrestrial eutrophication
Aquatic eutrophication
–N-equivalents
–P-equivalents
Photochemical ozone formation–impacts
on vegetation
Photochemical ozone formation–impacts
on human health
Chronic ecotoxicity in aquatic ecosystems
(ETWC)
Acute ecotoxicity in aquatic ecosystems
(ETWA)
Chronic ecotoxicity in terrestrial ecosystems
(ETSC)
Chronic ecotoxicity in aquatic ecosystems
(ETWC)
Acute ecotoxicity in aquatic ecosystems
(ETWA)
Chronic ecotoxicity in terrestrial ecosystems
(ETSC)
Human toxicity, via air
Human toxicity, via air
Human toxicity, via water
Human toxicity, via soil
Resource depletion
GW
OD
AC97
NE
–
–
PO
EDIP97/2003
EDIP97/2003
EDIP97
EDIP97
EDIP97
EDIP97
EDIP97
World
World
Europe
Europe
Europe
Europe
Europe
7.73E+03
2.05E−02
5.48E+01
4.59E+01
8.32E+00
2.82E−01
1.58E+01
8.70E+03
1.03E−01
7.40E+01
1.19E+02
2.40E+01
4.00E−01
2.50E+01
kg
kg
kg
kg
kg
kg
kg
PO
EDIP97
Europe
1.34E+01
2.50E+01
kg C2H4 eq/person/year
AC03
TE
AE
–
–
POveg
EDIP2003
EDIP2003
EDIP2003
EDIP2003
EDIP2003
EDIP2003
Europe
Europe
Europe
Europe
Europe
Europe
3.93E+02
1.37E+03
4.59E+01
8.32E+00
2.82E−01
5.97E+04
2.20E+03
2.10E+03
5.80E+01
1.20E+01
4.10E−01
1.43E+05
m²UES/person/year
m²UES/person/year
kg NO3− eq/person/year
kg Neq/person/year
kg Peq/person/year
m² ppm hr/person/year
POhum
EDIP2003
Europe
2.84E+00
1.01E+01
m² ppm hr/person/year
ETWC-97
EDIP97
Europe
2.96E+06
3.52E+05
m3 water/person/year
ETWA-97
EDIP97
Europe
5.25E+05
2.91E+04
m3 water/person/year
ETSC-97
EDIP97
Europe
2.22E+05
9.64E+05
m3 soil/person/year
ETWC-03
EDIP2003
Europe
3.66E+06
–
m3 water/person/year
ETWA-03
EDIP2003
Europe
6.65E+05
–
m3 water/person/year
ETSC-03
EDIP2003
Europe
7.32E+04
–
m3 soil/person/year
HTA-97
HTA-03
HTW-97
HTS-97
RD
EDIP97
EDIP2003
EDIP97
EDIP97
EDIP97
Europe
Europe
Europe
Europe
World
3.58E+10
4.73E+08
4.72E+04
8.06E+03
8.17E−01
–
m3 air/person/year
year−1
m3 water/person/year
m3 soil/person/year
PR/person/year
EDIP2003 assessments as an example, it can be seen that
whereas formaldehyde and butadiene appear to dominate
the impact potential when using EDIP97 (31% and 19%,
respectively), benzene is by far the largest contributor to the
impact in the EDIP2003 assessment (55%) where exposure
is more realistically represented.
The coverage of substances is not responsible for the
differences between the old and the new normalization
references in Table 1 since the CFs are available for the
same chemicals in both calculations. However, the methodological advances, represented here by the introduction
of a more geographically explicit exposure modelling, tend
to modify the distribution of the impact potentials significantly as visible from Table 3. Although arising from a
specific improvement within the same methodology, these
3.06E+09
1.71E+08
5.22E+04
1.27E+02
CO2 eq/person/year
CFC11eq/person/year
SO2 eq/person/year
NO3− eq/person/year
Neq/person/year
Peq/person/year
C2H4 eq/person/year
discrepancies demonstrate the well-known issue that the use
of different characterization methods for an impact category
can lead to large inconsistencies in the obtained results
(Dreyer et al. 2003; Pant et al. 2004).
4.3 Influence of inventory modelling
In parallel to continuous improvements in characterization
models, the development of inventory analysis can also be a
significant source of changes in normalization references as
they aim to increase accuracy and representativeness of the
estimated impact scores. The inventory modelling related to
NMVOCs and pesticides—see Section 2.2—is discussed
below with respect to influences on the normalization
references.
Int J Life Cycle Assess (2011) 16:401–409
405
Table 2 Main contributors to the normalization references for the EDIP non-toxic impact categories
Substances
Emission
GW (%) OD (%) AC97 (%) NE (%) PO (%) AC03 (%) TE (%) AE (%) POveg (%) POhum (%)
compartment
Carbon dioxide
Carbon monoxide
Total NMVOCs
Nitrous oxide
Methane
Total ODS
CFCs
HCFCs
Methyl bromide
Carbon tetrachloride
Halons
Nitrogen oxides (NOX)
Ammonia
Air
Air
Air
Air
Air
Air
Air
Air
Air
Air
Air
Air
Air
67
3
–
6
18
4
–
–
–
–
–
–
–
–
–
–
–
–
–
53
24
11
10
1
–
–
–
–
–
–
–
–
–
–
–
–
–
37
35
–
–
–
–
–
–
–
–
–
–
–
–
–
–
20
77
–
2
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
22
28
–
–
–
–
–
–
–
–
–
–
–
42
58
–
–
–
–
–
–
–
–
–
–
–
–
–
–
5
24
–
–
–
–
–
–
–
–
70
–
–
8
36
–
1
–
–
–
–
–
–
55
–
Sulphur oxides (SOX)
Total-N
Total-P
TOTAL
Air
Water
Water
–
–
–
99
–
–
–
100
28
–
–
100
–
84
16
100
–
–
–
100
50
–
–
100
–
–
–
100
–
80
20
100
–
–
–
99
–
–
–
100
The cut-off of the substance contribution reported here is 1%; contributions 10–30% are marked in italics; contributions above 30% are marked in bold
GW global warming, OD ozone depletion, AC97 acidification (EDIP97), NE nutrient enrichment (EDIP97), PO photochemical ozone formation
(EDIP97), AC03 acidification (EDIP 2003), TE terrestrial eutrophication (EDIP 2003), AE aquatic eutrophication (EDIP 2003), POveg
photochemical ozone formation impacts on vegetation (EDIP 2003), POveg photochemical ozone formation impacts on human health (EDIP
2003), ODS ozone-depleting substances
4.3.1 Issues related to NMVOC and pesticide inventories
In their update of the normalization references for EDIP toxic
impacts, Stranddorf et al. (2005) demonstrated that the
specification of individual substances unveils underestimations caused by the widely used simplifying approach to
characterize groups of substances, e.g. NMVOCs, as a
whole. The specifications of NMVOCs in the current
inventory (see details in ESM 2) tend to confirm those
assertions: NMVOCs turn out to govern the human toxic
impacts, via air and via soil, inducing the EDIP97 normalization references to increase by factors of ca. 12 and 63,
respectively, compared to their previous values (see Table 1).
Similar results occur from a more substance-specific
treatment of the emissions of pesticides, but the differences
observed in Table 1 between the EDIP97 normalization
references calculated by Stranddorf et al. (2005) and those
calculated in this study are not only explained by the
specification into active ingredients but also by the change in
emission modelling—see Section 2.2. In this study, the
pesticides are modelled as direct emissions from the field to
either air or water. As a result, the contribution to the
terrestrial ecotoxic potential becomes much lower than what
is typically obtained when the applied quantities of pesticides are modelled as emissions to agricultural soil (e.g. in
Stranddorf et al. 2005).
Despite the specification of the NMVOCs, which tends
to increase the impact potential (cf. above), the overall
result for the EDIP97 normalization reference for terrestrial
ecotoxicity is a drop by a factor of 4.3. Conversely, the
impact potentials for aquatic ecotoxicity increase due to the
inclusion of direct emissions of pesticides to the freshwater
environment, for chronic effects by a factor of around 8.4.
As a consequence, using the old set of normalization
references in combination with the substance-specific treatment of NMVOCs and pesticides and the consideration of
agricultural fields as a part of the technosphere could
introduce a considerable bias in the obtained results. For the
ecotoxic impact categories presented above, the discrepancy
between the two normalized impact scores could be as large as
a factor of 36 compared to the use of the updated set of
normalization references (Fig. 1). This could lead to improper
recommendations based on the results of the study. The need
to keep regular updates in phase with the development of the
LCA methodology itself, both at the characterization and at
the inventory levels, is strongly supported by these findings.
4.3.2 Guidance for improving inventories of NMVOCs
and pesticides
As it was found that the differentiation of substance groups
into individual substances can have a significant influence on
406
Int J Life Cycle Assess (2011) 16:401–409
Table 3 Main contributors to the normalization references for the EDIP 97 and 2003 toxic impact categories
Substances
Emission
compartment
ETWC97 (%)
ETWA97 (%)
ETSC97 (%)
ETWC03 (%)
ETWA03 (%)
ETSC03 (%)
HTA97 (%)
HTA03 (%)
HTW97 (%)
HTS97 (%)
1,3-Butadiene
Acrolein
Benzene
Benz(a)pyrene
Butanol
Benzene
Chlorpyrifos
Copper
Cypermethrin
Dioxins
Ethene
Formaldehyde
Hexanes
Air
Air
Air
Fresh water
Air
Marine water
Fresh water
Fresh water
Fresh water
Air
Air
Air
Air
–
–
–
4
–
4
53
8
3
–
–
–
2
–
–
–
2
–
2
8
4
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
5
82
–
–
–
–
4
–
4
56
6
4
–
–
–
2
–
–
–
2
–
2
9
3
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
5
82
–
19
3
14
–
12
–
–
–
–
–
–
31
–
8
–
55
–
5
–
–
–
–
–
–
13
–
–
–
2
–
–
–
–
–
–
3
–
–
–
–
–
88
–
–
–
–
–
–
–
–
–
–
Iron
Lead
Lead
Mercury
Fresh water
Fresh water
Air
Agricultural soil
5
–
–
3
–
–
–
–
–
4
–
–
2
–
–
–
–
–
–
–
–
–
–
6
–
2
–
–
–
–
Mercury
Mercury
Parathion-methyl
Zinc
VOC, unspecified
TOTAL
Air
Fresh water
Fresh water
Fresh water
Air
–
–
–
14
2
–
95
–
–
–
77
–
–
96
–
–
–
–
–
9
96
–
–
–
14
2
–
96
–
–
–
79
–
–
97
–
–
–
–
–
9
96
–
–
–
–
–
16
95
–
–
–
–
–
7
94
3
43
38
–
3
–
94
–
–
–
–
–
7
95
c
The cut-off of substance contribution reported here is 2%; contributions 10–30% are marked in italics; contributions above 30% are marked in bold
ETWC ecotoxicity, water chronic (EDIP97 or 2003); ETWA ecotoxicity, water acute (EDIP97 or 2003); ETSC ecotoxicity, soil chronic (EDIP97 or
2003); HTA human toxicity via air (EDIP97 or 2003); HTW human toxicity via water (EDIP97); HTS human toxicity via soil (EDIP97); VOC
volatile organic compounds
PE EU1994
PE EU2004
ETWC
4
3
ETSC
4
3
2
2
ETSC
1
With old set of
normalization references
(Stranddorf et al., 2005)
1
ETWC
With new set of
normalization references
(This study)
Fig. 1 Example of normalized results obtained when using an old set
and a new set of normalization references for EDIP97 to assess the same
product system. ETSC ecotoxicity, soil chronic; ETWC ecotoxicity,
water chronic; PEEU2004 Person Equivalent based on Europe 2004
the resulting normalization references, a default approach to
apply generic characterization factors by grouped emission
sources was developed for the situation where the data needed
to support a substance-specific inventory are not available to
the LCA practitioner (for physical reasons, e.g. measurements, or for legal reasons, e.g. confidentiality), or uncertainties associated with the specifications are too high.
Following the approach presented in Hauschild and Wenzel
(1998), NMVOC characterization factors, differentiated
according to their emission source and sector and applicable
to Europe, were calculated for the EDIP toxic impact
categories for 80 different source types (see ESM 1). No
default factors were calculated for pesticides since the
emissions have a very strong dependency on local conditions
of application, e.g. the applied agricultural practice.
Another issue highlighted in this study lies in the setting of
boundaries between the technosphere and the biosphere,
which is often improperly done in the current practice of
pesticide emission modelling. Today, several databases and
LCA software still inventorize the full applied quantity of
Int J Life Cycle Assess (2011) 16:401–409
pesticides as direct emissions to agricultural soil, whereas the
latter shall be part of the technosphere (see Section 2.2). The
68 pesticides included in the Ecoinvent database are thus
considered as emissions to agricultural soil, taking 100% of
the applied active ingredients and letting the characterization
model deal with their fate (Nemecek and Kägi 2007).
However, most impact assessment models are not able to
distinguish the fates of pesticides from those of other
compounds, which are unintentionally released (e.g. metals
in sewage sludge applied to agriculture). Generally, a large
fraction of pesticides is taken up by plants or degraded in
the field or on the leaves, and this fraction does not affect
the environment outside the field. A sensitivity analysis was
performed on the EDIP97 normalization references in order
to evaluate the divergence arising from using an improper
pesticide inventory. The inventory described in this study
(see Section 2.2) was used, but pesticide emissions to air
(5%) and water (0.1%) were substituted by 100% emissions
to soil. Results show that human toxicity is overall not
affected since pesticides play a negligible role in the
assessment whereas impact potentials are ca. 3–7 times
lower to what they should be for aquatic ecotoxicity and
more than 165 times too high for terrestrial ecotoxicity.
These large discrepancies for ecotoxicity impacts support
the recommendation that product life cycle inventories must
be corrected to include only emissions from the field before
using the normalization references reported in this study.
5 Uncertainty and sensitivity analysis in relation
to inventory settings
5.1 Uncertainty and bias
Only a qualitative assessment of uncertainties was deemed
possible, identifying the main sources of uncertainties.
Normalization references for the non-toxic impact categories generally have a reasonable reliability due to considerable experience with reporting inventories for the
associated emissions at the national and European levels,
and the relatively stable characterization models. However,
considerable efforts are still required to reach such a level
of quality for the toxic impacts because of (1) the absence
of characterization factors for relevant organic substances
additional to those presently covered, (2) the modelling
uncertainties related to the determination of the existing
characterization factors, and (3) the incompleteness of the
European emission inventory used to calculate the normalization references.
The former two refer to uncertainties inherent to the
EDIP methodology. Currently, the EDIP97 methodology
has factors for a few hundred chemicals, and although these
include many priority chemicals, it is expected that a
407
number of toxic substances of relevance for the human and
ecotoxic impacts at a European level may still be without
characterization factors in this methodology. In addition,
characterization factors for individual substances are
strongly dependent on the availability of data on substance
characteristics, and they may thus change in time as new
knowledge about a substance is generated. However, the
largest uncertainties in this study are likely to reside in the
latter of the above identified uncertainty sources because
only a limited number of substances could be inventorized,
and the reliability of the data for some of the most
contributing substances is questionable due to the extrapolations applied to arrive at the data.
The influence of this issue was observed when applying
the normalization references on a few distinct life cycle
inventories from the Ecoinvent database (not shown here).
Upon normalization, a number of metals (e.g. iron,
thallium, strontium, chromium (+VI)), initially not included
in the normalization inventory, turned out to contribute
significantly to the toxic impact categories. The omission of
these metal emissions in the inventory of the normalization
references lead to a bias in normalization with too high toxic
impacts, which might threaten the validity of the interpretation. It was therefore chosen to expand the normalization
inventory by including emissions of these metals from the
energy generation through a combination of European energy
figures with emission factors from the Ecoinvent database
(EUROSTAT 2010; Ecoinvent Centre 2007) (already
accounted for in the references given in Table 1).
5.2 Sensitivity analysis on inventory robustness
To further investigate the sensitivities of the inventory built in
this study, normalization references for EDIP97 toxic impact
categories were calculated using a different European inventory
from Sleeswijk et al. (2008; revised, Sleeswijk, 2010, personal
communication), which is based on the emission year 2000.
Table 4 summarizes the most influential differences between
the approaches taken by Sleeswijk et al. and by this study.
Table 4 illustrates that the deviations in the calculated
normalization references (ratio shown) arise from differences in the inventory of a very limited number of
substances. The modelling of pesticides is thus entirely
responsible for the deviation observed for the terrestrial
ecotoxicity normalization reference and partly explains the
deviation for aquatic ecotoxicity. The deviations in the
other impact categories can typically be assigned to a few
other inconsistencies in the inventory choices, viz. the
selection of the data sources and the type of extrapolations
applied when inventorizing NMVOCs and waterborne
releases of heavy metals and dioxins.
Considering the rather different inventory approaches
taken in the two studies, it is interesting that the
Impact category
Chronic ecotoxicity
in aquatic ecosystems
Inventory aspect
Sleeswijk et al. (2008; revised, Sleeswijk,
2010, personal communication)a
This study
Ratiob
Influence on the impact potential
Pesticide modelling
Pesticides as 100% emitted to soil
Pesticides as 0.1% emitted to
freshwater and 5% to air
Extrapolations based on consumption
data and agriculture modes in the
UK and DK
45.9
Contribution of pesticides equals ca. 70% with inventory
from this study whereas no pesticide contributes in the
assessment with inventory from Sleeswijk et al. where
nothing is emitted to water nor to air.
c
Extrapolations based on GDP or areas
Chronic ecotoxicity
in terrestrial ecosystems
Heavy metals (HM) to
freshwater
EPER database used for EU-15,
complemented by extrapolations
with GDP
OSPAR and HELCOM reports
complemented by GDP extrapolations
Higher emissions in this study (factors 46 and 35 for Cu
and Zn, respectively), leading to higher impact
potentials from HM emitted to aquatic ecosystems in
this study compared to Sleeswijk et al.
Dioxins emitted to
freshwater
Emissions to water extrapolated from
USA, Japan and Canada
Not included
Waterborne dioxins accounting for 10% with inventory
from Sleeswijk et al. The extrapolated emission data
for Europe was found to be too uncertain to include in
this study, so there is no contribution to the
normalization reference.
Iron (and some other metals,
e.g. Cr(+VI) and Sr) to
freshwater
Pesticide modelling
Not included
Rough estimates for iron
(and these other metals) based
on energy production in Europe
Pesticides as 0.1% emitted to
freshwater and 5% to air
Extrapolations based on
consumption data in Europe and
agriculture practices in
UK and DK
Significant contribution of iron (and strontium to a lesser
degree) in this study (5.5%).
Pesticides as 100% emitted to soil
Extrapolations based on GDP or areas
0.007
Terrestrial ecotoxicity potential is dominated at ca. 100%
by pesticide contributions in Sleeswijk et al., while
main contributors are NMVOCs in the present
study (99%)
NMVOC emissions
(specified)
Most emissions of NMVOCs to air
extrapolated from Canada,
US and Japan data
(incl. formaldehyde)
Differentiation of NMVOCs based
on emission data and
sector-specific distributions
9.1
NMVOCs dominant in both assessments (62% in
Sleeswijk et al. and 96% in this study, both driven by
formaldehyde and butadiene contributions) but lower
NMVOC emissions are considered in the inventory of
Sleeswijk et al. (hence the lower normalization
reference resulting from the latter)
Human toxicity,
via water
Dioxins emitted to
freshwater
Emissions to water extrapolated from USA,
Japan and Canada
Not included
1.1
Waterborne dioxins accounting for 6% with inventory
from Sleeswijk et al.
Thallium (and some other
metals, e.g. Cr(+VI),
Fe and Sr) to freshwater
NMVOC emissions (specified)
Not included
Rough estimates for thallium
(and these other metals) based on
energy production in Europe
Differentiation of NMVOCs based
on emission data and
sector-specific distribution
Human toxicity,
via soil
a
Most emissions of NMVOCs to air
extrapolated from Canada,
US and Japan reports
(incl. formaldehyde)
Inventory of (Sleeswijk et al. 2008) revised by the authors (Sleeswijk, 2010, personal communication)
b
Ratios of normalization references (this study)/(Sleeswijk, 2010, personal communication)
c
Acute ecotoxicity on aquatic ecosystems not reported as comparisons are similar to the ones for chronic ecotoxicity
Contribution of thallium (1.2%) to impact potential in
this study
23.2
NMVOCs dominant in both assessments (40% in
Sleeswijk et al. and 97% in this study, both driven by
benzene contributions) but lower NMVOC emissions
are considered in the inventory of Sleeswijk et al.
(hence the lower normalization reference resulting
from the latter)
Int J Life Cycle Assess (2011) 16:401–409
Human toxicity,
via air
408
Table 4 Inventory discrepancies between Sleeswijk et al. (2008; revised, Sleeswijk, 2010, personal communication) and this study that influence the EDIP97 normalization references for the toxic
impact categories
Int J Life Cycle Assess (2011) 16:401–409
normalization references end up within 1–2 orders of
magnitude for all the toxic impact categories. On the other
hand, this finding documents that the normalization contributes to increasing the uncertainty of the toxic impact
categories compared to the non-toxic categories, and they
emphasize the need to concentrate efforts to better
inventorize central substances or groups of substances,
such as dioxins and some specific heavy metals.
6 Conclusions
The study provides the most updated set of publicly
available normalization references for the EDIP method
(both EDIP97 and EDIP2003) and a set of inventory data
covering all the common midpoint categories to be applied
in the calculation of European normalization references for
other LCIA methodologies. The references are calculated
for the emission year 2004, and for the non-global impact
categories, they represent the European background load.
For the toxic impact categories, emphasis was put on
including recent developments in inventory modelling. The
differentiation of emissions of groups of chemicals, such as
NMVOCs and pesticides, into individual substance emissions was performed, and pesticide emissions were modelled to the ecosphere rather than to the technosphere to
ensure compatibility with characterization models. The
outcome helped highlight the inconsistencies still inherent
in current LCI practices, where the harmonization of the
approaches followed appears as an important challenge to
take up in the field of LCA.
Furthermore, important sources of uncertainties were
identified for the toxic impact categories, both at the
characterization and at the inventory levels. For the latter,
the most significant issues are related to incompleteness in the
coverage of substances. Practical trials and comparisons with
other inventory information were performed to quantitatively
estimate these gaps. The findings clearly demonstrate the need
to complement inventories with reliable information on key
substances such as heavy metals or dioxins.
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