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InLCA Session IIB - Risk-Based Approaches
Click here to download a zipped copy of the abstracts and slide presentations for this session.
Comparison of Two Equivalency Factor Approaches with Simplified Risk Assessment for LCIA of Toxicity Impact Potential

Presenter: D. A. Tolle
(slides in pdf)

D. A. Tolle, D. J. Hesse, G. B. Chadwell, J. S. Cooper, and D. P. Evers

Battelle
505 King Avenue
Columbus, OH 43201
Phone: 614-424-7591
FAX: 614-424-3404
E-mail: tolled@battelle.org


This study compares two equivalency factor approaches and a simplified risk assessment (RA) approach, for life cycle impact assessment (LCIA) characterization of impact potentials for the Inhalation Toxicity impact category. The equivalency approaches include the Persistence, Bioaccumulation, and Toxicity (PBT) and the multimedia fate modeling methods, which are supported by algorithms that incorporate acute toxicity benchmarks and data on fate/potential exposure. The simplified RA approach involved dispersion modeling using site-specific environmental data to determine environmental concentrations of emissions and compare them with threshold values considered safe for humans. The RA method was simplified by conducting dispersion modeling on only those air emissions where the release concentration before dispersion exceeded the threshold concentration. The case study used for this evaluation was based on life-cycle inventory data for manufacture of the GBU-24 munition, which was simplified to look at only one manufacturing site.

Comparison of the three LCIA methods is based on the amount of effort for data collection and analysis, as well as correlation of the impact potential scores. The effort to collect site-specific environmental data and conduct air dispersion modeling on 9 chemicals for the simplified RA method, required about 24 times more effort than the PBT method and about 4 times more effort than the multimedia fate modeling method. As the number of regions/sites and chemical emissions decreases, the improved correlation of the multimedia fate modeling method is more likely to justify the increase in effort for use of this method instead of the PBT method. The multimedia fate modeling method may be more appropriate for LCIAs involving comparative assertions or governmental policy decisions, while the PBT method may be adequate for internal company decisions. Although the simplified RA method is assumed to be the most accurate of the three methods evaluated, the substantial effort for obtaining environmental characteristics information needed for dispersion modeling does not seem justified when there are more than two sites included in the LCIA.

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LCA for Products with Indoor Lifetimes: Review of Methods and Issues, and Applications to Flooring Materials

Presenter: Gregory Norris

Gregory A. Norris

Sylvatica/Harvard School of Public Health
147 Bauneg Hill Rd, Suite 200
North Berwick, ME 03906
Phone: 207-676-7640
FAX: 207-676-7647
E-mail: norris@sylvatica.com

Yurika Nishioka. Harvard School of Public Health

Susan Doll, Harvard School of Public Health

Olivier Jolliet, EPFL, Switzerland


Life Cycle Assessment traditionally emphasizes (or in many cases, pays exclusive attention to) releases of pollutants to the outdoor environment. In most LCAs, if indoor emissions are included in the inventory (as they have been in many LCAs of paints, for example), indoor emissions are not differentiated from emissions to the outdoor environment. Indoor emissions can occur during manufacturing stages (occupational exposures) as well as during product installation and use. For a number of products with significant indoor emissions in their life cycles, indoor emissions may be associated with potentials for exposure which are orders of magnitude higher than those of the products' life cycle releases the outdoor environment.

The differing potential for unit emissions to lead to human health consequences as a function of whether they occur indoors or outdoors can be addressed using the concept of "Exposure efficiency." Exposure efficiency is the probability that a molecule of pollutant emitted from a source will reach and be inhaled by a human receptor. It can be estimated for different release environments by a variety of means.

This paper reviews the spectrum of methods that have been advanced by LCA practitioners for dealing with usage phase emissions to indoor air. In the context of a case study LCA comparison of flooring materials, the paper then addresses a number of issues which arise in LCAs of products with indoor air emissions. These issues include the wide variability in indoor air emissions within product classes; the need to convert testing data on emissions rates into total lifetime emissions data for use in LCA; and the availability of data on specific chemical species within important categories such as VOCs.

The paper proposes a new and integrated method for consistent treatment of indoor and outdoor emissions in LCA, and illustrates how use of this new method impacts results, conclusions, and data requirements for LCA.

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A Risk-Based Life-Cycle Assessment Framework for Analyzing Complex Technologies

Presenter: Robert Anex
(slides in pdf)

Robert P. Anex

Science & Public Policy Program
University of Oklahoma
100 East Boyd St., Rm S-202
Norman, Oklahoma 73019
Phone: 405-325-2299
FAX: 405-325-7695
E-mail: rpanex@ou.edu


This paper describes a risk-based life-cycle assessment (LCA) framework for analyzing complex technologies. The essence of LCA is the identification and evaluation of the relevant environmental implications of a product or process across its entire life cycle. One of the most powerful features of LCA is its ability to prevent environmental problems from being "solved" by being shifted to another part of the life cycle. Two of LCA's weaknesses as it is usually implemented are its aggregation of impacts across spatial and temporal dimensions, and its failure to account for risks. The impacts to the environment and human health considered in an LCA are fundamentally probabilistic and governed by risks. Because of the unique ways that people address decisions involving risk, for LCA to be a truly useful decision making guide, it must present risk information in ways that inform decision makers about the trade-offs between risks and benefits. Considering risks is particularly important in managing complex technological systems that present large system uncertainties. This paper describes the complementary roles of risk assessment and LCA in the evaluation of complex technologies and defines the need for a technique that integrates LCA and risk assessment. The paper then describes a risk-based life-cycle assessment (rbLCA) framework utilizing an iterative LCA process that spatially and temporally disaggregates important risk effects and expands the number of endpoints so that risks can be meaningfully assessed and evaluated by decision makers and stakeholders. The paper also describes the software tools that are required to support the rbLCA framework and how such tools can be developed by building upon existing LCA and risk assessment software.

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Consequences of the Damage Approach on the Valuation Step and LCA in General

Presenter: Patrick Hofstetter

Patrick Hofstetter

U.S. EPA (MS-466)
ORISE Research Fellow
Visiting Scientist at Harvard School of Public Health Phone:
26 W, Martin Luther King Dr.
Cincinnati, Ohio 45268
513-569-73 26
FAX: 513-569-71 11
E-mail: hofstetter.patrick@epa.gov


The damage approach has recently received high attention in Life Cycle Impact Assessment as it aims to model complex cause-effect relationships up to endpoints while present state-of-the-art methods model up to midpoints only. The aim of the damage approach is to model changes to a few safeguard subjects. The safeguard subjects should reflect elements that society considers of ultimate relevance. This shift in the modeling from midpoints to endpoints implies as well a shift in the division of tasks between model developers and decision makers. While the uncertain assumptions of the final consequences of midpoint results were so far within the interpretation of (expert) panel members or decision makers they are now supported by damage models. These endpoint models are uncertain as well because they rely on value laden choices and judgements. This is the interface where the new division of work occurs.

A powerful graphical tool for dominance analysis was developed to make transparent model results from the damage approach to decision makers. Examples show how manipulative such tools can be without careful introduction. This includes the knowledge on what decision makers do observe, perceive, or expect as a consequence of environmental effects. Practically this means that the reference system may considerably vary with decision makers and that the interpretation tool has to allow for this variation. Within Life Cycle Assessment the focus is on impacts induced by the change in resource use and emission patterns due to improvements within or change to another product system. This implies marginal changes and therefore the valuation has to deal with the weighting of marginal damages. This adds to the inherent difficulty to perceive effects spread in time and place. A number of possible solutions are presented, empirical validation being the next step.

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Screening and Ranking in the Context of Implicit Toxicological Concern:
A Comparison of Methodologies and Requirements

Presenter: David W. Pennington

David W. Pennington

ORISE Research Fellow
Systems Analysis Branch, NRMRL
U.S. EPA
Cincinnati, OH
E-mail: pennington.david@epamail.epa.gov


A large number of methodologies have been proposed to support the relative comparison of chemical emissions in the context of implicit toxicological concern. Nevertheless, the selection of a methodology typically remains subjective and influenced by resource availability (time, knowledge and money). The results of three extensive studies are outlined in this presentation to help practitioners address such issues:

I) The merits and applicability of five categories of methodology are first illustrated with the help of a hierarchical framework and straightforward case study. The hierarchy is based on the level of representation of the environmental mechanisms (from fate, via exposure to toxicological potency) and perceived sophistication.

II) A comparison is then presented of two of the more prominent but structurally different methodologies (tiers 4 and 5 in the hierarchy) used in the US. The WMPT facilitates comparison in terms of key properties using a framework of expert judgment to reflect levels of concern in terms of Persistence, Bioaccumulation and Toxicity (PBT). Toxic Equivalency Potentials (TEPs) account for chemical fate, multi-pathway exposure and toxicity using a multimedia model structure. Using the same data for 318 organic chemicals and minimizing scenario differences, a strong relationship and parallel support role is demonstrated to exist between these two particular approaches in the context of human health.

III) Focusing data collection efforts can dramatically reduce the time required to compare a large number of chemicals or emissions using the more sophisticated multimedia approaches in the hierarchy. Based on model insights and a stated trade-off between data needs and error, four straightforward guidelines are presented to help predetermine which degradation rates (air, water, soil and sediment) are likely to be pertinent. The introduced error is generally less than an order of magnitude for the 318 chemicals when compared to the full human health, while the data requirements (1272 half-lives) and associated collection times are drastically cut.


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