EPA/600/R-12/554 I July 2012 I www.epa.gov/research
United States
Environmental Protection
Agency
Tool for the Reduction and
Assessment of Chemical and Other
Environmental Impacts (TRACI)
TRACI version 2.1
User's Guide
Office of Research and Development
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EPA/600/R-12/554
August 2012
Tool for the Reduction and Assessment of
Chemical and Other Environmental
Impacts (TRACI)
USER'S MANUAL
Software Name and Version Number: TRACI version 2.1
STD Standard Operating Procedure (SOP)
Number S-10637-OP-1-0
Software Baseline Documentation
Number S-10637-CP-2-0
Jane Bare, Principal Investigator (TLP)
6/18/2012
Daniel Young, STD QAM
6/22/2012
Matthew Hopton, SAB Acting Branch Chief
6/29/2012
Sustainable Technology Division
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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TRACI2.1
Tool for the Reduction and Assessment of Chemical and other environmental Impacts 2.1
r \
Inventory of Stressors
Chemical Emissions
Fossil Fuel Use
/^Impact Categories \
Ozone Depletion
Global Warming
Acidification
Eutrophication
Smog Formation
Human Health
Particulate
Cancer
Noncancer
Ecotoxicity
Fossil Fuel Use
TRACI
Tool for the Reduction and
Assessment of Chemical and
other environmental Impacts
Characterization (e.g.. Human Health Noncancer)
3 * F
Air C
4
\
Ozone Depletion
/'Global Warming
/'Human Health Noncancer
User Manual
July 2012
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Table of Contents
Abbreviations 5
Technical Background 6
Abstract 6
Introduction 6
Inventory 8
Impact Assessment Methodologies 9
Acidification 11
Eutrophication 11
Global Climate Change 12
Ozone Depletion 12
Human Health Paniculate 13
Human health Cancer, Noncancer, and Ecotoxicity 14
Photochemical Smog Formation 15
Resource Depletion 16
Interpretation 16
Summary 17
Disclaimer 17
HowtoUseTRACI2.1 18
Impact Category Headings 18
Example Case Study Results 19
Example 1 19
Example 2 20
References 21
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CTU - Comparative Toxicity Unit
DOE - Department of Energy
EPA - Environmental Protection Agency
GWP - Global Warming Potential
ISO - International Organization of Standardization
LCA - Life Cycle Assessment
LCIA - Life Cycle Impact Assessment
NEI - National Emissions Inventory
NIST - National Institute of Standards and Technology
NRMRL - National Risk Management Research Laboratory
OOP - Ozone Depletion Potential
ORD - Office of Research and Development
PM - Particulate Matter
STD - Sustainable Technology Division
TRACI - Tool for the Reduction and Assessment of Chemical and other environmental Impacts
TRI - Toxics Release Inventory
US - United States
USETOX -model developed under UNEP-SETAC Life Cycle Initiative
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Abstract
TRACI2.1 (the Tool for the Reduction and Assessment of Chemical and other environmental Impacts) has been
developed for sustainability metrics, life cycle impact assessment, industrial ecology, and process design impact
assessment for developing increasingly sustainable products, processes, facilities, companies, and communities.
TRACI 2.1 allows an expanded quantification of stressors that have potential effects, including ozone depletion,
global warming, acidification, eutrophication, photochemical smog formation, human health paniculate effects,
human health cancer, human health noncancer, ecotoxicity, and fossil fuel depletion effects. Research is ongoing to
quantify the use of land and water in a future version of TRACI. The original version of TRACI was released in
August 2002 (Bare et al. 2003) followed by a release of TRACI 2.0 in 2011 (Bare 2011).
Impact assessment for environmental decision making in areas such as sustainability metrics, life cycle assessment
(LCA), and industrial ecology involve the quantification of a large number of potential impacts. Unfortunately,
completing comprehensive assessments for all potential effects at a high level of simulation, sophistication and
disaggregation require excessively large amounts of time, data, knowledge, and resources. It therefore follows that
every study must be limited in some aspects of sophistication and/or comprehensiveness.
While conducting several LCA case studies, the U.S. Environmental Protection Agency's (US EPA's) National Risk
Management Research Laboratory conducted a literature survey of existing methodologies (Heijungs et al. 1992a,
Heijungs et al. 1992b, Guinee et al. 2002, Goedkoop et al. 2009, Goedkoop & Spriensma 1999, Goedkoop et al.
1996, Hauschild & Wenzel 1998a, Hauschild & Wenzel 1998b, Wenzel et al. 1997, Wenzel & Hauschild 1997,
Jolliet et al. 2003). As it was apparent that no tool existed that would allow a level of sophistication,
comprehensiveness, and applicability to the United States, the US EPA decided to begin development of a software
tool to conduct impact assessment with the best applicable methodologies within each category. This research effort
was called TRACI - the Tool for the Reduction and Assessment of Chemical and other environmental Impacts (Bare
et al. 2003).
As dictated within the ISO 14042 guidance in this area, an LCA has several steps, some of which may be iterative:
inventory, impact assessment, normalization (optional), and either valuation, grouping, or weighting (optional)
(International Standards Organization 2000). It is critical to consider the importance of each of these stages (e.g.,
without a strong inventory possessing high data quality, the results of the impact assessment will be less valuable).
In addition, while it is important to show as much comprehensiveness as possible within each study, as was recently
demonstrated at an US valuation exercise conducted at NIST, some impact category results may receive much more
attention (Gloria et al. 2007).
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The first step in developing this tool was to select the impact categories for analysis and methodology development.
It was soon recognized that the selection of these impact categories is a normative decision depending on what is
valued to the individual user. In an attempt to be fully comprehensive in the original selection of impact categories,
EPA initiated a taxonomy study of possible impacts (and impact categories) which could be included (Bare & Gloria
2008). From this greater list of impact categories, a smaller more manageable list of impact categories was selected
for inclusion into TRACI and subsequently, TRACI 2.1. This "manageable" list was selected for a variety of
reasons, including consistency with existing regulations and policies, perceived importance, and ease of modeling.
The traditional pollution categories of ozone depletion, global warming, human health criteria, smog formation,
acidification, and eutrophication were included within TRACI due to various programs and regulations within EPA
and recognizing the value of minimizing effects from these categories. The category of human health was further
subdivided into cancer, noncancer, and criteria pollutants (with an initial focus on particulates) to better reflect the
focus of EPA regulations and to allow methodology development consistent with the U.S. regulations, handbooks,
and guidelines. Smog formation is recognized as a significant environmental issue within the US and has separate
regulations, which address its prevention. Smog formation effects were kept independent and not further aggregated
with other human health impacts because environmental effects related to smog formation would have become lost
in the process of aggregation. Paniculate pollutants within TRACI are various sizes and forms of paniculate matter
(e.g., PM 2.5 and PM10) and pollutants which lead to respiratory impacts related to particulates (e.g., sulfur oxides
and nitrogen oxides). They were maintained as a separate human health impact category allowing a modeling
approach that can take advantage of the extensive epidemiological data associated with these well-studied impacts.
The resource depletion categories are recognized as significant in the US, especially for fossil fuel use, land use, and
water use. Although not included in TRACI 2.1, research is underway to include land use and water use impacts.
The categories within TRACI 2.1 are shown in Figure 1, with land use and water use being listed for future
inclusion. It should be noted, however, that this list of impact categories is considered a minimal set that may be
expanded in future versions. Further discussion about the history and development of TRACI, including the
minimization of assumptions and value choices by the use of midpoint indicators, and a comparison to other
methodologies may be found in supplemental documentation (Bare et al. 1999, Bare et al. 2000, Bare et al. 2003,
Bare 2006, Bare & Gloria 2008, Bare & Gloria 2006, Hofstetter et al. 2002, Pennington & Bare 2001, Pennington et
al. 2000).
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Figure 1. TRACI 2.1 framework
r \
Inventory of Stressors
Chemical Emissions
Fossil Fuel Use
,
-^
^Impact Categories ^\
Ozone Depletion
Global Warming
Acidification
Eutrophication
Smog Formation
Human Health
Particulate
Cancer
Noncancer
Ecotoxicity
-
' Characterization (e.g.. Human Health Noncancer)\
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Ozone Depletion
TRACI
Tool for the Reduction and
Assessment of Chemical and
other environmental Impacts
^Global Warming
/Human Health Noncancer
Inventory
The TRACI framework begins with a user provided inventory of Stressors. Within a gate-to-gate analysis, inventory
data are often available from the facility or facilities. Within an LCA this may be supplemented by inventory data
from suppliers, and/or publicly available databases such as those listed below: the 2006 US EPA's Greenhouse Gas
Emissions (US Environmental Protection Agency 2008h, US Environmental Protection Agency 2008g, US
Environmental Protection Agency 2008f), the 2006 US EPA's National Emissions Inventory (NEI) for Criteria
Pollutants (US Environmental Protection Agency 2007b), the 2002 Hazardous Air Pollutants (US Environmental
Protection Agency 2002), the 2006 US Department of Agriculture's (USDA's) Simulation of Nutrient Losses (US
Department of Agriculture - Natural Resources Conservation Service 2006), the 2005 US Department of Energy's
(US DOE's) Energy Consumption Estimates for fossil fuel depletion (US Department of Energy - Energy
Information Administration 2008), the 2005 US EPA's Toxics Release Inventory (TRI) (US Environmental
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Protection Agency 2005a), and the NREL LCI database (US Department of Energy - National Renewable Energy
Laboratory 2008). Data quality and applicability should be considered when including data sources.
Supporting data, such as the TRI database, which were not originally collected or developed for this intention may
have some shortcomings. 1) Only exceedance of minimal reporting requirements may be included. 2) Groups of
substances may be lumped together (e.g., mercury, mercury compounds, copper, copper compounds, chromium,
chromium compounds, lead, and lead compounds). 3) The quality of the data may be uncertain and in many cases
hard to predict. TRACI users are encouraged to use the highest quality data whenever possible for minimal data and
modeling uncertainty.
Because TRACI is an impact assessment tool, the selection of inventory data source will not be further discussed
here. The heart of the TRACI framework is the characterization of each of the impact categories.
Whether the analysis is being conducted within an LCA, process design, or a sustainability metrics basis, in all
impact categories, the underlying methodologies within TRACI utilize the amount of the chemical emission or
resource used and the estimated potency of the stressor.
The estimated potency is based on the best available models and data for each impact category. For some impact
categories (e.g., ozone depletion potentials, global warming potentials), there is international consensus on the
relative potency of the chemicals listed. For other impact categories, the relative potency may be dependent on
models related to chemical and physical principles and/or experimental data. Descriptions on individual impact
categories are provided below and give greater detail about the modeling underlying each category.
In some impact categories, the location of the emission or resource used is of importance to the potency of the
stressor, and the practitioner is encouraged to maintain the location with each stressor. In these cases, the individual
stressors do not simply have one potency factor, but a potency factor at each of the locations. The calculations
should then be conducted at each location and then summed up to see the total impact for the study overall. As an
example, if an impact category (i) has a fate factor (F), and potency factor (P), then the site-specific analysis may be
calculated as follows
I' = X XX F' P1 M (1)
L^ L^ L^ xms xms xms
s x m
Where:
/' = the potential impact of all chemicals (x) for a specific impact category of concern (i)
Fxms = the fate of chemical (x) emitted to media (m) at site (s) for impact category (i)
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the potency of chemical (x) emitted to media (m) at site (s) for impact category (i)
Mxms = the mass of chemical (x) emitted to media (m) at site (s)
There are many times when the site-specific location is not utilized. For example, for some individual impact
categories, location does not influence the fate, transport, and potency to any great extent, and thus only one
characterization factor is presented for global use (e.g., global climate change, stratospheric ozone depletion). At
other times, the individual locations of the emissions are not known for a specific study and since all impact
categories allow non site-specific characterization, the more site-generic characterization factors may be used. In
these situations, the generalized equation without respect to location would be:
/'' = V CF' * M (2)
L-t xm xm ^ '
Where:
/' = the potential impact of all chemicals (x) for a specific impact category of concern (i)
CFxm = the characterization factor of chemical (x) emitted to media (m) for impact category (i)
Mxm = the mass of chemical (x) emitted to media (m)
Although the original version of TRACI was released with site-specificity available for many of the impact
categories, the vast majority of TRACI users have not been utilizing the site-specific features. This release of
TRACI 2.1, as described below will focus on the US average characterization.
For emission related categories, characterization factors are available for the media listed in Table 1.
Table 1. Characterization Factors are available for the media listed for each impact category.
Impact Category
Ozone Depletion
Global Climate
Acidification
Eutrophication
Smog Formation
Human Health Paniculate
Human Health Cancer
Human Health Noncancer
Ecotoxicity
Media
Air
Air
Air, Water
Air, Water
Air
Air
Urban Air, Nonurban Air, Freshwater, Seawater, Natural Soil,
Agricultural Soil
Urban Air, Nonurban Air, Freshwater, Seawater, Natural Soil,
Agricultural Soil
Urban Air, Nonurban Air, Freshwater, Seawater, Natural Soil,
Agricultural Soil
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Acidification is the increasing concentration of hydrogen ion (H+) within a local environment. This can be the result
of the addition of acids (e.g., nitric acid and sulfuric acid) into the environment, or by the addition of other
substances (e.g., ammonia) which increase the acidity of the environment due to various chemical reactions and/or
biological activity, or by natural circumstances such as the change in soil concentrations because of the growth of
local plant species.
Acidifying substances are often air emissions, which may travel for hundreds of miles prior to wet deposition as acid
rain, fog, or snow or dry deposition as dust or smoke paniculate matter on the soil or water. Sulfur dioxide and
nitrogen oxides from fossil fuel combustion have been the largest contributors to acid rain (US Environmental
Protection Agency 2008q).
Substances, which cause acidification, can cause damage to building materials, paints, and other human-built
structures, lakes, streams, rivers, and various plants and animals. The sensitivity of various environments can depend
on a number of factors including: the local buffering capacity, the local plant and animal species, and the existing
acidity within the environment (US Environmental Protection Agency 2008c).
Consistent with the focus on providing midpoint assessments, TRACI2.1 uses an acidification model which
incorporates the increasing hydrogen ion potential within the environment without incorporation of site-specific
characteristics such as the ability for certain environments to provide buffering capability (Wenzel et al. 1997,
Wenzel & Hauschild 1997).
Eutrophication is the "enrichment of an aquatic ecosystem with nutrients (nitrates, phosphates) that accelerate
biological productivity (growth of algae and weeds) and an undesirable accumulation of algal biomass" (US
Environmental Protection Agency 2008d). Although nitrogen and phosphorus play an important role in the
fertilization of agricultural lands and other vegetation, excessive releases of either of these substances may provide
undesired effects on the waterways in which they travel and their ultimate destination. While phosphorus usually has
a more negative impact on freshwater lakes and streams (U.S. Environmental Protection Agency 2008), nitrogen is
often more detrimental to coastal environments (Ecological Society of America 2000).
Some of the major substances which have a role in this impact category are difficult to characterize including
emissions from: wastewater treatment plants, decaying plant life pulp and paper mills, food processing plants, and
fertilizers used in agricultural, commercial, and individual household locations (US Environmental Protection
Agency 1997). For example, the majority of fertilizer (when utilized correctly) provides the benefits for which it was
purchased. However, depending on the slope of the fields, the precipitation, and volatilization of the fertilizer, some
of this product may go beyond the original intended boundaries and cause unintended consequences downstream. It
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is these unintended consequences that are considered to be the emission in this case; whereas, the portion of the
application that achieved its goal of fertilizing fields was considered to be useful product (US Department of Energy
- National Renewable Energy Laboratory 2008).
The original methodology utilized in TRACI allowed site-specific characterization, which is not supported, in the
current version. Additional substances, which have the potential to cause eutrophication, have been added to TRACI
2.1.
"Global warming is an average increase in the temperature of the atmosphere near the Earth's surface and in the
troposphere, which can contribute to changes in global climate patterns. Global warming can occur from a variety of
causes, both natural and human induced. In common usage, "global warming" often refers to the warming that can
occur as a result of increased emissions of greenhouse gases from human activities" (US Environmental Protection
Agency 2008b). The current trend is to use the phrase 'climate change' instead of global warming to denote the
other changes which may occur in addition to temperature change (US Environmental Protection Agency 2008p).
During the last 200 years, the sources of greenhouse gases have increased (mostly caused from the increased
combustion of fossil fuels (US Environmental Protection Agency 2008a)), while the sinks have decreased (e.g.,
deforestation and land use changes). The U.S. is keeping track of the greenhouse gas emissions (US Environmental
Protection Agency 2008h, US Environmental Protection Agency 2008g) and has a policy in place for greenhouse
gas reductions (US Environmental Protection Agency 2008p).
TRACI 2.1 utilizes global warming potentials (GWPs) for the calculation of the potency of greenhouse gases
relative to CO2 (IPCC (Intergovernmental Panel on Climate Change) 2001). Consistent with the guidance of the
United Nations Framework Convention on Climate Change (UNFCCC) (UNFCCC -The United Nations Framework
Convention on Climate Change 2003), the US EPA uses GWPs with 100-year time horizons. TRACI 2.1 expands
the list of substances found within the original version of TRACI and utilizes a hierarchy of data sources consistent
international acceptance. This hierarchy of sources includes the most current GWPs published by the IPCC
(Solomon 2011, Solomon et al. 2007, IPCC (Intergovernmental Panel on Climate Change) 2001, IPCC
(Intergovernmental Panel on Climate Change) 1996).
Ozone within the stratosphere provides protection from radiation, which can lead to increased frequency of skin
cancers and cataracts in the human populations. Additionally, ozone has been documented to have effects on crops,
other plants, marine life, and human-built materials. Substances which have been reported and linked to decreasing
the stratospheric ozone level are chlorofluorocarbons (CFCs) which are used as refrigerants, foam blowing agents,
solvents, and halons which are used as fire extinguishing agents (US Environmental Protection Agency 2008J). Over
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20 years ago, the United States signed the Montreal Protocol to reduce CFC production, and later implemented even
more stringent reductions, which have led to a complete end of production of CFCs (by 1996) and halons (by 1994).
Levels of total inorganic chlorine have been declining since 1998, and recovery of the ozone layer is expected in
about 50 years (US Environmental Protection Agency 2008m).
There is international consensus on the use of ozone depletion potentials (ODPs), a metric proposed by the World
Meteorological Organization (WMO) (Solomon & Albritton 1992, WMO (World Meteorological Organization)
1999), for calculating the relative importance of substances expected to contribute significantly to the breakdown of
the ozone layer. The US EPA maintains websites listing various options for ODPs (US Environmental Protection
Agency 2008k, US Environmental Protection Agency 20081). These options are consistent with the US and WMO
documents used internationally (WMO (World Meteorological Organization) 2003, US Environmental Protection
Agency 1992, US Environmental Protection Agency 2003, WMO (World Meteorological Organization) 1999, US
Environmental Protection Agency 20081, US Environmental Protection Agency 2008J, US Environmental Protection
Agency 2008k). Within TRACI 2.1, the most recent sources of ODPs were used for each substance.
Although this category may be called the human health criteria pollutants category, it deals with a subset of the
criteria pollutants, i.e., paniculate matter and precursors to particulates. Paniculate matter is a collection of small
particles in ambient air which have the ability to cause negative human health effects including respiratory illness
and death (US Environmental Protection Agency 2008n). Numerous epidemiology studies show an increased
mortality rate with elevated levels of ambient paniculate matter (US Environmental Protection Agency 2008n).
Paniculate matter may be emitted as particulates, or may be the product of chemical reactions in the air (secondary
particulates). The most common precursors to secondary particulates are sulfur dioxide (SO2) and nitrogen oxides
(NOx). Common sources of primary and secondary particulates are fossil fuel combustion, wood combustion, and
dust particles from roads and fields (US Environmental Protection Agency 2008n). Paniculate matter is divided into
two major groups of concern: "inhalable coarse particles" which are between 2.5 micrometers and 10 micrometers in
diameter, like dust from roadways, and "fine particles" which are smaller than or equal to 2.5 micrometers in
diameter, and are often the products of combustion (US Environmental Protection Agency 2008o). Sensitive
populations such as children, the elderly, and people with asthma are more susceptible to experiencing higher
consequences (US Environmental Protection Agency 2008i). Although national US standards have existed since
1971, even more stringent standards were placed in 2006 (US Environmental Protection Agency 2006).
The method for calculation of human health impacts includes the modeling of the fate and exposure into intake
fractions (i.e., that portion of the emitted substance, which is expected to be inhaled by a human being). These intake
fractions are calculated as a function of the amount of substance emitted into the environment, the resulting increase
in air concentration, and the breathing rate of the exposed population. The increasing air concentrations are a
function of the location of the release and the accompanying meteorology and the background concentrations of
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substances, which may influence secondary particle formation. Substances were characterized using PM2.5 as the
reference substance (Humbert 2009).
During the development of the original TRACI, human health was represented by three impact categories based on
the current structure of the EPA regulations and the chemical and physical behaviors of the pollutants of concern.
CalTOX was determined to be the best model for human health cancer and noncancer (McKone 1993), and the input
parameters were selected to be consistent with the EPA Risk Assessment Guidelines and the Exposure Factors
Handbook (U.S. Environmental Protection Agency 1997, US Environmental Protection Agency 1989a, US
Environmental Protection Agency 1989b). Research was conducted to determine the source of the major
uncertainties and influence of site-specific parameters on the human toxicity potentials (Hertwich et al. 1999). The
probabilistic research showed that for the majority of the TRI substances, chemical data (e.g., toxicity and half-life)
had the most significant impact on data variability/uncertainty and that site-specific parameters had little effect on
the relative human toxicity potentials (Hertwich et al. 1999). This research supported later development of global
toxicity potentials for human health cancer and noncancer.
Under the Life Cycle Initiative of the United Nations Environment Program (UNEP) / Society of Environmental
Toxicology and Chemistry (SETAC) various international multimedia model developers of CalTOX, IMPACT
2002, USES-LCA, BETR, EDIP, WATSON, and EcoSense created a global consensus model known as USEtox
(Hauschild et al. 2008, Rosenbaum et al. 2008, USEtox Team 2010). Over the course of a series of workshops and
numerous communications, model results from the original models were compared to determine the most influential
parameters and largest sources of differences between the models using 45 organic substances, which were selected
for their diversity in environmental partitioning, exposure pathway, persistence, and air transport. The USEtox
model adopted many of the best features of the above-named models and was used to develop human health cancer
and noncancer toxicity potentials and freshwater ecotoxicity potentials for over 3000 substances including organic
and inorganic substances.
This list of 3000 substances goes beyond the list included within the original TRACI, because initially TRACI was
focused on covering those chemicals of concern within the US (e.g., TRI chemicals). It has since been recognized
that today's global economy often requires the inclusion of suppliers who are outside of the US within countries
who may have their own lists of reportable chemicals. The USEtox expanded set allows this expansion into
chemicals of concern globally.
USEtox is developed with two spatial scales: continental and global. The environmental compartments within the
continental scale includes: urban air, rural air, agricultural soil, industrial soil, freshwater, and coastal marine water.
USEtox includes most of the pathways found in the original EPA Risk Assessment Guidelines, including inhalation,
ingestion of drinking water, produce, meat, milk, and freshwater and marine fish.
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The USEtox model has been selected to replace the CalTOX model as the basis for the TRACI impact categories of
human health cancer, noncancer, and ecotoxicity. It should be noted that some of the characterization factors
included within the USEtox model are recommended while others are simply interim and should be used with
caution (Rosenbaum et al. 2008, Hauschild et al. 2008).
The recommended units for the USEtox human health cancer, noncancer, and ecotoxicity are: CTUcancer,
CTUnoncancer, and CTUeco, respectively. Although USEtox guidance allows for the combination of cancerous and
noncancerous impacts, users of TRACI are encouraged to maintain these categories independently. Individual
emissions to media may be combined to consolidate emissions to these three categories.
Ground level ozone is created by various chemical reactions, which occur between nitrogen oxides (NOx) and
volatile organic compounds (VOCs) in sunlight. Human health effects can result in a variety of respiratory issues
including increasing symptoms of bronchitis, asthma, and emphysema. Permanent lung damage may result from
prolonged exposure to ozone. Ecological impacts include damage to various ecosystems and crop damage. The
primary sources of ozone precursors are motor vehicles, electric power utilities and industrial facilities (US
Environmental Protection Agency 2008e).
Within the Leiden University's CML 2002 Handbook (Guinee et al. 2002) are listed various options for "summer
smog" modeling including: 1) Photochemical Ozone Creation Potentials (POCPs) (Derwent et al. 1996, Derwent et
al. 1998, Jenkin & Hayman 1999, Andersson-Skold et al. 1992, Derwent 1991), and 2) Maximum Incremental
Reactivity (MIR) (Carter 1994, Carter 1997, Carter 2000). More recent work is now available from Carter for MIR
values. Some of this work was conducted specifically for TRACI (Carter 2007, Carter 2008).
Carter's MIRs have been selected for use within TRACI 2.1 for the following reasons. 1) It was developed
specifically for the US. 2) It is comprehensive in impacts, covering human and environmental effects. 3) It has the
most comprehensive substance coverage allowing greater differentiation of effects when available. The full set of
POCPs recently available only cover 128 substances and the TRACI 2.1 MIRs cover nearly 1200 substances (Carter
2007, Carter 2008, Carter 2010b, Carter 2012). 4) It is the method that is used and recommended by the US EPA
and individual states within the United States for other environmental programs, including cap and trade programs
(US Environmental Protection Agency 2007a, US Environmental Protection Agency 2005b, US Environmental
Protection Agency).
Many of the methods, including MIRs prior to the TRACI research, did not have a NOx value on the same scale as
the VOCs. This was true for MIRs since the MIR reflects the degree of reactivity with NOx, a concept that is not
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reflective of NOx reactivity with NOx. At the request of this author, Carter was asked to develop and document a
proxy NOx value on the same scale as the MIR (Carter 2008, Carter 2010a).
Modifications were made in the development of TRACI2.1 when compared to the original version of TRACI. First,
the MIRs were updated to include the latest work of Carter (Carter 2010b). More chemicals were added and the total
number of pollutants now quantified in this category is nearly 1200 substances. Second, to be consistent with the
presentation and units of other impact categories a reference substance was adopted. Thirdly, those twelve
substances, which have a negative MIR, were set to zero. While it may be true there is a slightly beneficial effect to
the reduction of ozone concentrations upon increased concentration of these pollutants, it was decided that providing
"credit" for the additional release of pollutants was not generally a good practice. This is consistent with other
recommendations in which negative MIRs were not given credits (Carter 2003).
Resource depletion is an extremely important issue for the use and development of sustainability metrics and LCA
methodologies. Unfortunately, it is one of the most difficult issues to quantify while minimizing value choices and
assumptions. Because all of the previously described categories had legislation or international agreements related to
their control, it was relatively easy to utilize the models, which were in existence for fate, transport, and potency for
each impact category. A parallel track does not exist for these resource depletion categories. Therefore, it is
recognized up front the quantification of these impact categories will be the most controversial.
Based on a review performed by the author, a determination was made that the initial resource depletion categories
which would be addressed within TRACI would be fossil fuel use, land use, and water use. A non site-specific
recommendation for fossil fuel use characterization was included within the original version of TRACI (Bare et al.
2003, Goedkoop & Spriensma 1999) and this reference methodology is maintained within this release of TRACI
2.1. Over the next few years, the author will be concentrating research efforts in land and water use and should have
additional recommendations. In both cases, land and water use recommendations are expected to be site specific,
because of the unique properties of location, meteorology, and existing ecosystems.
Notice that no conclusions can be drawn about the relative importance of the scores when compared across impact
categories. Since each impact category has different units it is not appropriate to simply look at the values of each
impact category and determine from this point which impact category is of most concern. To look at relative
importance would involve normalization and weighting. None of the above impact categories have been aggregated
using normalization or weighting. Even the human health impact categories have been maintained independently in
these examples.
Whether using TRACI within previously developed software, or using it within an EXCEL spreadsheet, one of the
most important phases is a proper interpretation of results. One important component of interpretation is an
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understanding of the uncertainty involved with various results. Uncertainty in the calculated results can be highly
variable depending on the impact category and its underlying methodology. Within the USEtox Manual, for
example, they mention that characterization factors associated with USEtox may span three orders of magnitude on
the individual factors. Other impact categories such as ozone depletion may be based on chemical data and models
with less associated uncertainty for individual substances. These uncertainties can best be understood by consulting
the original sources of characterization factors.
TRACI 2.1 is now available for use in sustainability, life cycle impact assessment, process design, or pollution
prevention. All of these applications require quantitative data to guide decision making which impacts the current
and future generations. TRACI 2.1 has been updated to include additional substances and updated methodologies.
Over the next few years, the US EPA will be continuing to expand research into the areas of land use and water use.
Use of TRACI, including but not limited to the impact assessment modeling, does not create regulatory or scientific
approval by the US EPA on any issues to which it is applied, nor does it release any users from any potential
liability, either administratively or judicially, for any damage to human health or the environment. The US EPA
does not make any warranty concerning the correctness of the database, any actions taken by third parties as a result
of using the model, or the merchantability or fitness for a particular purpose of the model. The EPA does not
endorse any products or services.
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The TRACI_2012 spreadsheet includes a number of worksheets. These worksheets and their function are described
below.
TRACI2.1
Fossil Fuels
Substances
References
Provides information concerning the version, source, and disclaimer for using
TRACI2.1.
Provides information specific to the characterization of fossil fuels.
Includes substances, CAS numbers, and their characterization factors for all of the
substance based impact categories.
Provides references for all of the characterization factors within TRACI.
CAS # - Chemical Abstract Services Number
Substance Name - Substances Name (may include categories)
Alternate Substance Name - Limited Alternatives are available
Global Warming Air (kg CO2 eq/kg substance) = Global Warming Potentials for Air Emissions
Acidification Air (kg SO2 eq/kg substance) = Acidification Potentials for Air Emissions
Acidification Water (kg SO2 eq/kg substance) = Acidification Potentials for Water Emissions
HH Paniculate Air (PM2.5eq/kg substance) = Human Health Paniculate (and secondary paniculate matter
precursors) Potentials for Air Emissions
Eutrophication Air (kg N eq/kg substance) = Eutrophication Potentials for Air Emissions
Eutrophication Water (kg N eq/kg substance) = Eutrophication Potentials for Water Emissions
Ozone Depletion Air (kg CFC-11 eq/kg substance) = Ozone Depletion Potentials for Air Emissions
Smog Air (kg O3 eq/kg substance) = Smog Formation Potentials for Air Emissions
Ecotox CF (CTUeco/kg), EmairU, freshwater = Freshwater Ecotoxicity Potentials for Urban Air Emissions
Ecotox CF (CTUeco/kg), Em. airC, freshwater = Freshwater Ecotoxicity Potentials for Rural Air Emissions
Ecotox CF (CTUeco/kg), Em. Fr.waterC, freshwater = Freshwater Ecotoxicity Potentials for Freshwater Emissions
Ecotox CF (CTUeco/kg), Em. seawaterC, freshwater = Freshwater Ecotoxicity Potentials for Seawater Emissions
Ecotox CF (CTUeco/kg), Em. Nat.soilC, freshwater = Freshwater Ecotoxicity Potentials for Natural Soil Emissions
Ecotox CF (CTUeco/kg), Em. Agr.soilC, freshwater = Freshwater Ecotoxicity Potentials for Agricultural Soil
Emissions
CF Flag Ecotox = Characterization Factor Flag for Ecotoxicity Potentials
Human health CF (CTUcancer/kg), Emission to urban air, cancer = Human health Cancer Potentials for Urban Air
Emissions
Human health CF (CTUnoncancer/kg), Emission to urban air, non-cane. = Human health Non-cancer Potentials for
Urban Air Emissions
Human health CF (CTUcancer/kg), Emission to cont. rural air, cancer = Human health Cancer Potentials for Rural
Air Emissions
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Human health CF (CTUnoncancer/kg), Emission to cont. rural air, non-cane. = Human health Non-cancer Potentials
for Rural Air Emissions
Human health CF (CTUcancer/kg), Emission to cont. freshwater, cancer = Human health Cancer Potentials for
Freshwater Emissions
Human health CF (CTUnoncancer/kg), Emission to cont. freshwater, non-cane. = Human health Non-cancer
Potentials for Freshwater Air Emissions
Human health CF (CTUcancer/kg), Emission to cont. sea water, cancer = Human health Cancer Potentials for Sea
water Emissions
Human health CF (CTUnoncancer/kg), Emission to cont. sea water, non-cane. = Human health Non-cancer
Potentials for Sea water Emissions
Human health CF (CTUcancer/kg), Emission to cont. natural soil, cancer = Human health Cancer Potentials for
Natural Soil Emissions
Human health CF (CTUnoncancer/kg), Emission to cont. natural soil, non-cane. = Human health Non-cancer
Potentials for Natural Soil Emissions
Human health CF (CTUcancer/kg), Emission to cont. agric. soil, cancer = Human health Cancer Potentials for
Agricultural Soil Emissions
Human health CF (CTUnoncancer/kg), Emission to cont. agric. soil, non-cane. = Human health Non-cancer
Potentials for Agricultural Soil Emissions
CF Flag HH carcinogenic = Characterization Factor Flag for Human Health Carcinogenic Potentials
CF Flag HH non-carcinogenic = Characterization Factor Flag for Human Health Non-carcinogenic Potentials
To calculate the score for each individual impact category, multiply the mass of the substance (kg) emitted in the
given compartment (e.g., urban air, agricultural soil) with the characterization factor for that substance in each
impact category.
Assume the emissions include the following.
Halon-1301 = 2 kg emissions to air
Which has a GWP for air = 7140,
And an OOP for air = 16.
Would yield the following scores
For GWP = 2 kg * 7140 kg CO2 eq / kg substance = 14,280 kg CO2 eq
For ODP = 2 kg * 16 kg CFC-11 eq / kg substance = 32 kg CFC-11 eq
Similarly, the cancer and noncancer categories are treated as independent impact categories and should not be
aggregated. The media emissions can be aggregated however.
Assume the emissions include the following.
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Benzene = 5 kg emissions to rural air
Which has a Smog Potential for air = 0.72 O3 eq / kg substance,
And an Ecotoxicity Potential for rural air = 0.064 CTUeco / kg substance,
And a Human health Cancer Potential to rural air = 1.2 E-07 CTUcancer / kg substance
And a Human health Noncancer Potential to rural air = 3.0 E-08 CTUnoncancer / kg substance
And Benzene = 10 kg emissions to freshwater
And an Ecotoxicity Potential for freshwater = 66 CTUeco / kg substance,
And a Human health Cancer Potential to freshwater = 2.4 E-07 CTUcancer / kg substance
And a Human health Noncancer Potential to freshwater =6.1 E-08 CTUnoncancer / kg substance
The above two emissions of benzene would yield the following scores.
For Smog = 5 kg * 0.72 ozone eq / kg substance = 3.6 ozone eq
For Ecotoxicity = (5 kg * 0.064 CTUeco / kg substance) + (10 kg * 66 CTUeco / kg substance) = 660 CTUeco
For Human Health Cancer = (5 kg * 1.2 E-07 CTUcancer / kg substance) + (10 kg * 2.4 E-07 CTUcancer / kg
substance) = 3.0 E-06 CTUcancer
For Human Health Noncancer = (5 kg * 3.0 E-08 CTUnoncancer / kg substance) + (10 kg * 6.1 E-08
CTUnoncancer / kg substance) = 7.6 E-7 CTUnoncancer
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