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Toxic Data Bias and the Challenges
of Using LCA in the Design Community
Presented at GreenBuild 2003 – Pittsburgh PA
Tom Lent
Principal • Energy & Environmental Consulting • 2464 West St, Berkeley, CA 94702
510-845-5600 • tlent@igc.org
1. OVERVIEW
Awareness is growing in the design community of the need to account for impacts throughout
the life cycle when assessing the environmental characteristics of materials. Until recently, Life
Cycle Assessment (LCA) tools to help rationalize this intricate task have been inaccessible to
most due to the need for complex software tools and expensive proprietary databases. Now with
the development of software tools such as BEES 3.0, relatively simple affordable tools that
compare LCA information for different building materials are becoming available to the design
community and the USGBC is considering incorporating LCA into LEED.
This paper outlines some important inherent structural constraints on the ability of LCA to
address a range of toxic chemicals and their related human health issues. It particularly focuses
on toxicity hazards that are known by science to be serious environmental health problems but
are as yet poorly quantified or otherwise not readily managed in an LCA framework. It explores
how these LCA constraints can guide the user away from a good understanding of the full
environmental health impacts and can lead to materials decisions that do not actually reflect the
user’s environmental goals. It also suggests approaches to overcome these problems to consider
before LCA tools are incorporated into LEED or otherwise used broadly by the design
community. The goal is to ensure that these tools serve the design community reliably and assure
that their use does not undermine the environmental and health goals they seek to promote.
2. LCA: POWER OF THE DOUBLE EDGED SWORD
Quantitative LCA tools have progressed tremendously and have become an effective means for
systematic internal industrial design analysis. When carried out by an individual manufacturer
using datasets they understand and manage, these analyses can provide excellent insight into the
impacts of alternative design pathways and be powerful tools for identifying environmental
impacts and selecting optimal design directions.
The application of these tools to material selection by the design community, however, presents
significant challenges that have not yet been overcome. The power of the LCA tool lies in the
wide ranging scope of its analysis, encompassing a large number of factors through which a
building material can impact the environment throughout its life cycle. At this state of
development, however, this scope can be a double-edged sword. Descriptions of LCA typically
imply that the analysis is complete, describing LCA as the analysis of the total environmental
Toxic Data Bias and LCA Challenges Tom Lent
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impact of a product through every step of its life.* While LCA designers are striving mightily to
improve the accuracy of their estimates and approximations, LCAs can never live up to the
expectation of total analysis set by such descriptions. By definition, LCAs must always have
boundaries limiting the impacts they attempt to model and are highly dependent upon industry
and science to provide useful data to drive the models. If the users don’t understand these
limitations, LCA tools can give the user a false sense of security that the tool is providing a
comprehensive, unbiased and final analysis of all of the environmental impacts resulting from
production, use and disposal of a material, ending the need to ask further critical questions. In
reality, serious data and analysis limitations inherent in current tools can lead them to strong but
hidden biases for materials with major environmental health impacts that are as yet inadequately
quantified or where acceptable health and safety threshold limits are in flux and dispute.
Persistent, bioaccumulative toxic (PBT) chemical releases are one key area that is highly
problematic to accurately represent in a quantitative assessment.
3. REVERSALS THROUGH UNCERTAINTY: VINYL VS. LINOLEUM CASE STUDY
A case study will demonstrate how LCA results can be dramatically affected by the effects of
data uncertainty. In fact results can be totally reversed.
The Vinyl Institute and several vinyl flooring manufacturers have been quick to promote that one
popular LCA tool – the BEES model (NIST 2002) - appears to rate vinyl composition tile (VCT)
as much more environmentally sound than linoleum. The Institute further implies that the
USGBC has endorsed this evaluation:
“The results show VCT ranks 20 to 30 percent higher in environmental performance and
90 to 170 percent higher in economic performance. Criteria for the rating include indoor
air quality, solid waste, acid rain, global warming and natural resource depletion. The
BEES model for evaluating building products has been adopted as an official tool of the
U.S. Greenbuilding Council (sic), and is used by architects, builders, contractors and
other specifiers who want to select environmentally friendly products.” (Vinyl Institute
1998)
Indeed the comparison looks even more dramatic than the Vinyl Institute suggests. With no
modification of parameters, BEES gives normalized environmental performance score results of
.0521 for generic linoleum and .0131 for generic VCT (where a lower score represents a lower
environmental impact). From this analysis it appears that linoleum has 3.98 times the
environmental impact of VCT. BEES allows for the fact that all environmental impacts are not of
equal import. BEES provides the option of using one of two different weighting schemes
developed by a US EPA Scientific Advisory Board or Harvard University or a user defined
scheme. As interpreted in BEES, the US EPA weighting scheme, for example, suggests that
global warming impacts are more than three times as important as ozone depletion impacts
(Lippiatt 2002). Applying the US EPA weighting criteria to the analysis reduces the spread, but
not enough to change the story. Linoleum still appears to have more than twice the
environmental impact of VCT (environmental performance scores are 0.333 for linoleum vs.
* A typical description states: “LCA analyzes the total environmental impact of all materials and energy flows, either
as input or output, over the life of a product from raw material to end-of-life disposal or rebirth as a new product.”
(Montgomery 2003)
Toxic Data Bias and LCA Challenges Tom Lent
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0.153 for VCT). For the designer with thousands of materials to specify, this may be the end of
the story. Unexpectedly, the VCT appears to be better for the environment. Life is surprising and
sometimes convenient.
A deeper look at the numbers within the BEES model and study of the controversy around vinyl,
however, reveal a different story. A careful comparison of each of the impact categories across
the two floorings reveals that BEES actually calculates that VCT performs worse than linoleum
in every category in which either of the materials has a significant impact, with impact factors
that are anywhere from 1.4 to 8 times higher in every category, except eutrophication – excess
nutrient runoff*. Linoleum even outperforms VCT on fossil fuel depletion despite the fact that
linoleum currently is imported from Europe. In this analysis, however, the eutrophication flows
for linoleum are calculated to outweigh the impacts in all other categories combined.
Eutrophication is indeed a significant environmental problem, affecting aquatic life. The BEES
results, however, raise two important questions: Does linoleum’s contribution to eutrophication
really outweigh the human health issues raised by the vinyl life cycle and are LCA tools even
capable of actually making this comparison yet?
A look at one of the health impact concerns at issue in the life cycle of vinyl will help make clear
the challenges faced by LCAs in properly evaluating the health impacts of materials. Dioxins -
the most potent carcinogens known to science - are an unavoidable byproduct of the manufacture
of polyvinyl chloride (PVC) feedstock for VCT and of the combustion of PVC products
(Thornton 2002).
For an LCA to accurately capture and evaluate the health impacts of dioxin releases from the life
cycle of VCT, LCA planners must have access to validated quantifications of the amount of
dioxin emissions resulting from an average pound of PVC though its life cycle. Science is still
very early in its efforts to quantify dioxin flows in the environment. The vinyl industry points to
the US EPA Dioxin Assessment and notes that the latest draft identifies only 12.3g TEQ† as
coming from ethylene dichloride/vinyl chloride manufacturing. They point out that this is a tiny
fraction of the total EPA estimated dioxin flows of 3,252g TEQ (USEPA 2001a). Unfortunately,
this is likely just a tiny fraction of the actual flows of dioxin from the PVC life cycle. The EPA
Dioxin Assessment inventory represents only the flows that have been reliably characterized and
quantified, not an estimate of total flows. A tremendous volume of projected dioxin flows are
known to exist but have not yet been quantified reliably enough to be included in the official
EPA assessment. For example, the EPA estimates that landfill fires alone (with PVC the primary
chlorine donor and therefore a major dioxin factor) may contribute 1000g TEQ of dioxin per
year (USEPA 2001a). This is only one of a significant number of yet to be quantified dioxin
flows from the life cycle of PVC, including as yet poorly or unquantified combustion sources in
which PVC is a major chlorine donor (such as structural and vehicle fires) and disposal sites for
dioxins produced in the manufacture of PVC (such as landfills and injection wells) and better
* Eutrophication is the addition of mineral nutrients to the soil or water – in this case primarily from agricultural
practices used to raise the flax seed - which can increase algae growth, which in turn can lead to lack of oxygen,
impacting aquatic life.
† Dioxins are actually a family of chemicals – all potent but of varying toxic strength. “g TEQ” refers to “grams
toxic equivalent," a quantitative measure of the combined toxicity of a mixture of dioxin-like chemicals in reference
to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).
Toxic Data Bias and LCA Challenges Tom Lent
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quantified sources for which the fraction contributed by PVC has not yet been estimated (such as
burn barrels at 628 g TEQ , copper smelters and incinerators).
The result of the uncertainty in estimating dioxin flows is that the actual dioxin flows resulting
from PVC production and use are indeterminate. They likely total somewhere between one and
two orders of magnitude above the quantities listed in the inventory of the EPA assessment.
With a potent flow like dioxin this is potentially a very significant issue. The human health factor
rating in BEES for dioxin is more than 10,000 times higher than the next highest chemical
(diethanol amine) and a million or more times greater than the remainder (Lippiatt 2002). A
small difference in estimates of dioxin flows can have a massive impact on the outcomes.
Increasing the dioxin flow factor in BEES for VCT only by a factor of three would be sufficient
to totally eliminate the environmental advantage that BEES indicates for VCT over linoleum in
the initial comparison.
If only a portion of the EPA estimates eventually are confirmed, the end result for a VCT
material comparison will be dramatically changed – if the flow is included in the LCA.
Researching the origins of the dioxin flows in BEES, brought me to the PriceWaterhouse
Coopers DEAM database that drives the BEES analysis. On inquiry at PriceWaterhouse, I was
surprised to learn that that PVC flow model comes via France from the APME – the Association
of Plastics Manufacturers in Europe – who apparently conveniently have decided to leave dioxin
emissions entirely out of their model. Only dioxin emissions from coal combustion for electricity
production and from diesel transportation make it in to BEES*.
It should be noted that there are similar data concerns (except in the opposite direction) on the
linoleum side about whether the massive eutrophication impact that BEES displays is correct.
Resolution of these possible discrepancies could also reverse the results of the BEES analysis in
linoleum’s favor†.
LCAs as currently designed can only calculate and compare impacts based upon flows that are
well understood and quantified. For at least some prominent materials, only a small portion of
the total chemical flows that result in known human health impacts are well quantified. As is
made dramatically clear from the case of dioxin emissions from the PVC life cycle, the
magnitude of the missing or poorly characterized flows may well overwhelm all other impacts,
reversing the LCA analytical judgment of relative environmental impact when comparing
materials.
This is not meant to dismiss LCAs as a useful tool for the designer. LCAs can be very helpful in
assisting the designer to understand many significant environmental impacts of a material. This
case study demonstrates that use of BEES throws a strong spotlight on the enormity of the
eutrophication impact and the importance of addressing the agricultural practices involved. The
* Alexandre Rossin, PricewaterhouseCoopers LLP, Personal communication 10/17/03.
† Analysts from linoleum manufacturer Forbo have done their own internal LCAs and assert that the factor for
eutrophication from linoleum used in BEES is 2 orders of magnitude (100X) too high and suspect a
misunderstanding of functional units may have contributed to the error. If the current BEES eutrophication category
value (.0454) is reduced by 99% , the total environmental impact of linoleum drops from .0521 to .0071, flipping the
results. Linoleum ends up beating VCT with only 55% of the measured environmental impact – even before having
accounted for all of VCT’s dioxin related flows.
Toxic Data Bias and LCA Challenges Tom Lent
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case study, however, also demonstrates that any use of LCAs as a tool to compare materials must
be informed by knowledge of where flows are poorly characterized or totally missing and the
potential impact on the LCA of those flows. Failing to do this ensures that, at least in some cases
such as PVC, the LCA comparison will serve to mask the worst environmental impacts – in this
case the carcinogenic impact of dioxins - rather than clarify the tradeoffs and relative merits of
the materials. In so doing, uninformed LCA use can be expected to lead to environmentally
detrimental material choices.
4. MORE MISSING DATA: MAINTENANCE CHALLENGES
Dioxins are not the only significant flows unmeasured by LCAs. Another example is the
emissions from flooring materials over the lifetime of the installation. Most LCAs base their
flow assumptions about flooring emissions on the total of volatile organic compounds (VOCs)
emitted during the first 72 hours after installation. The theory of using this as a proxy for all
emissions from the floor is that VOC emissions from flooring products rapidly decline after
installation and become insignificant so only the initial emissions are meaningful. This approach
misses several other significant flows from installation that may far exceed the impact of the 72
hour post-installation VOC emissions, including both maintenance flows, such as VOCs and
sewage loads from wax and strip cycles and semi-volatile organic compound (SVOC) emissions
such as phthalates from PVC (Lundgren 2002), that occur over a much longer time frame than
the VOCs.
The emissions from cleaning, stripping and waxing maintenance activities are likely to be orders
of magnitude higher than the 72 hour post-installation VOC emissions. A recent LCA study
found that the amount of VOCs emitted from a single waxing of a floor is comparable to the
amount of VOCs emitted from the flooring itself over its entire life (Norris 2003). Two materials
with different maintenance requirements are likely to have vastly different lifetime VOC
emissions that are likely to dramatically alter the relative health impact balance between the
materials.
Accurately including the maintenance flows and properly weighting the impact of the exposures
in an LCA intended for universal use is very difficult, as maintenance procedures and exposures
vary widely from building to building. Rates of maintenance will vary widely depending upon
traffic, preferences, and budgets. Staff and patients in a healthcare facility that is fully
operational 24/7 are going to have far higher exposure to cleaning chemicals than occupants of a
9-5 office building where maintenance can be scheduled for evenings and weekends when
occupancy is low. To account for this, LCA programs will need to gather input from the user on
building occupancies and maintenance procedures and build that in to the model. Lacking that,
users must be made aware that not only are the maintenance-related flows excluded, but that the
impact of those flows could radically impact the indoor air quality results for floorings and other
maintained surfaces. Otherwise, again the results of a comparative analysis between two
materials with substantially different maintenance regimes will sometimes be quite counter to the
true comparative environmental impact.
Toxic Data Bias and LCA Challenges Tom Lent
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5. HOW DO WE REALLY SELECT MATERIALS? SCREENS VERSUS WEIGHTINGS
Most LCAs are currently configured to be completely based upon relative weightings. Every
impact is assumed to have a value that can be exchanged against another impact. For example,
two materials will be score about equally in an LCA using the EPA weighting if one has three
times the indoor air quality impact but only half the global warming impact of the competing
material.
Real world materials selection, however, doesn’t work that way. Specifiers work with a variety
of weightings, limits and absolute screens. Minimum standard criteria are established by building
codes for concerns such as flame spread. The building code is absolute on this issue, not
allowing more flame spread in exchange for more of another value like structural strength.
Owner values may also determine absolute criteria ranging from color and pattern, to life
expectancy and maintenance requirements. Owners may also place a combination of criteria on
other factors, such as cost. These might include both absolute criteria limit (must cost no more
than $X/yd) and a weighting (below that maximum price a cheaper product may outweigh
another value like ease of maintenance). Environmental impact analyses can and should be
similarly subject to more than just comparative weighting. Just as fire safety provided a strong
rationale for setting absolute standards for flame spread and screening out inappropriate
materials, other environmental and human health and safety concerns establish a strong rationale
for setting standards and screens on the chemical flows resulting from materials selection.
In some cases the rationale may be for a not-to exceed chemical standard, as in the case of the
California 1350 materials emissions standards. Previous emissions standards took more of a
fungible weightings approach in which any VOC emissions were allowable as long as the total of
all VOCs did not exceed a specified limit. The 1350 test, on the other hand, recognizes that each
of an increasing number of VOCs has a known limit beyond which chronic illness effects on
humans have been identified in scientific study and sets an absolute limit on the permissible
emissions of each individual compound based upon those health impact studies (Lent 2003). An
LCA tool that alerted the user if established VOC limits would ever be exceeded would be much
more useful than one that simply measures total VOCs and weighs that against all other impacts
and hence buries the issue behind a composite rating number. Even 1350 should not be the
endpoint for inclusion of life time emission issues. The 1350 test addresses VOCs released in the
first few months of a products life but not the SVOCs referred to earlier. Until and unless
adequate testing and modeling protocols can be established to inform safe levels, a precautionary
approach will need to be taken to address phthalates, brominated flame retardants, and other
SVOCs.
In other cases, chemicals have been clearly determined to be sufficiently harmful to warrant
outright elimination. CFCs and PCBs have been banned for use in the US (USEPA 2000 USEPA
1979) and hence any material that results in their use or production should be identified and
disallowed in an LCA. Similarly the US has committed in an international treaty “to reduce
and/or eliminate the production, use, and/or release of persistent organic pollutants” (POPs),
including through material substitution, to eliminate use of those materials that contribute to the
formation of POPs in any stage of their lifecycle (US EPA 2001b UNEP 2000). Useful LCAs
would support implementation of these agreements with warning flags, if not outright screens, on
materials that contribute to POPs formation.
Toxic Data Bias and LCA Challenges Tom Lent
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6. ACCOMMODATING DATA REALITIES: SUGGESTIONS FOR LCA
ENHANCEMENTS
To avoid the pitfalls identified here, LCA tools like BEES should consider incorporating a
number of enhancements:
Data uncertainties: Identify the significant uncertainties and quantification controversies in the
data and flag these uncertainties numerically and graphically to show the end user the effect they
may have on the end results through error bars and similar tools.
Use phase flows: Obtain user inputs on use patterns, preferences and maintenance procedures
and build that in to the models to allow modeling of use- and maintenance-related flows.
Chemical restrictions and screens: Build absolute chemical and maximum concentration level
screening into the model to allow application of legal limits, health research based standards,
international treaty obligations and precautionary specifications to the environmental flows.
Prime chemicals for absolute limits are persistent bioaccumulative toxics and others whose
manufacture, use or disposal results in generation or release of carcinogens (cancer causing
chemicals), teratogens (chemicals inducing birth defects in the developing fetus), reproductive
toxicants (chemicals that damage the functions of the reproductive system), developmental
toxicants (chemicals that stop or misdirect human development), or endocrine disruptors
(chemicals that disturb the operation of the endocrine system, affecting development and other
key bodily functions). This process will need to be one that continues to be updated for a long
time with ample use of precautionary principles for protective insurance as we await testing on
thousands of uncharacterized chemicals*.
7. CONCLUSION
LCAs are truly a double-edged sword. On the one hand they have the potential to provide the
design community with highly important information in the search for the most environmentally
friendly and healthy materials. On the other hand, the current reality is that they provide just one
portion of the picture in any comparative analysis of materials. LCAs, such as BEES, do not
generally incorporate information into their analyses about environmental health issues that are
not yet well quantified, are affected by user patterns, are precautionary or are subject to
maximum limits or absolute restrictions. By being portrayed as total analyses of environmental
flows, LCAs run the danger of lulling the design professional user into thinking that the provided
material comparison is complete and does not require any additional analysis.
A series of enhancements have been described that would help flag uncertainty issues,
incorporate use variability and acknowledge chemical restrictions and screens, bringing each of
these explicitly into the LCA analysis.
* The task of identifying chemical hazards and screening our materials choices for environmental and human health
and safety will be an ongoing one. Complete basic publicly available toxicity information (the Screening
Information Data Set, or SIDS) is available for less than 10% of the roughly 2,800 high production volume
chemicals (those produced in volumes over one million pounds per year). No toxicity information at all is available
for more than 40%. Even less is known about the tens of thousands more chemicals that are produced in smaller
volumes of for any of these chemicals in combination with each other. (US EPA 1999, Lowell 2003)
Toxic Data Bias and LCA Challenges Tom Lent
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Even with these enhancements, it remains critically important for the user to understand the
limitations of quantitative analysis in the face of scientific uncertainty. Put simply, this means
that science understands the existence and importance of many significant environmental health
hazards - like dioxin emissions - for which it can not yet provide reliable numbers to plug into
LCA type analyses. The lack of those numbers means that these issues do not show up in a
quantity based LCA as currently designed. The health impacts, however, do not go away and we
can ill afford to ignore them. For many of these issues, preemptive precautionary action to limit
or exclude use of materials involving certain targeted chemicals is the wiser, more responsible
and - considering potential liability issues - sometimes more economically conservative course
than waiting for certain scientific quantification.
Even with the best data available and more enhancements, LCAs will remain a tool that can only
provide one important part of the puzzle - the well quantified part. It will remain critical for the
design community to recognize the limitations on what quantification can do to guide materials
decision making. We must continue to take responsibility for understanding the challenges and
controversies around our materials choices and continue to make value judgments on the
precautionary issues at the boundaries of scientific certainty.
Toxic Data Bias and LCA Challenges Tom Lent
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8. REFERENCES
Lent, Tom. 2003. Review of the California 1350 Specification and Indoor Air Quality. Healthy Building
Network. Washington, DC. http://www.healthybuilding.net/healthcare/specification.html.
Lippiatt, Barbara C. 2002. BEES 3.0 Technical Manual and User Guide. NISTIR 6916. National Institute
of Standards and Technology. Gaithersburg, MD. October 2002. p. 27
Lowell Center for Sustainable Production. 2003. Integrated Chemicals Policy. University of
Massachusetts Lowell. Lowell, MA. p. 2.
Lundgren, B., et al. 2002. “Small Particles Containing Phthalic Esters in the Indoor Environment – A
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Montgomery, Margaret. 2003. “Life Cycle Assessment Tools” Architecture Week. 20 August 2003 P.
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Thornton, Joe, PhD. 2002. Environmental Impacts of Polyvinyl Chloride Building Materials. Healthy
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US EPA. 1979. United States Environmental Protection Agency. EPA Bans PCB Manufacture; Phases
Out Uses. press release. April 19, 1979. Sept 20. 2003. http://www.epa.gov/history/topics/pcbs/01.htm
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US EPA. 2001b. Persistent Organic Pollutants (POPs).
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UNEP. 2000. United Nations Environment Programme. Persistent Organic Pollutants,.
http://www.chem.unep.ch/pops/.
Vinyl Institute. 1998. Website. “Environmental Attributes of Vinyl, Vinyl Flooring Comes First in Life-
cycle Assessment”. Environmental Briefs. December 1998. 9/5/2003.
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