Page 176 - Materials Chemistry, Second Edition

MODELING THE AGRI-FOOD INDUSTRY WITH LIFE CYCLE ASSESSMENT 161

relevant impacts are relative to the stocks of the target and by-catch fish species
and seafood habitats, but indicators are currently under development.
Nonetheless, the impacts related to the agri-food product system are of
a very different nature compared to the traditional ones typically modeled in
LC A, which raises many issues regarding the application of the LCA approach.
For instance, agri-food systems require different considerations regarding the
definition of the functional unit, the system boundaries, the allocation issues,
the fertilizers and pesticides dispersion models, and the indicators for some
impact categories. (Sleeswijk, et ah 1997). Today there are many different
approaches, but there are no standardized methodological answers to these
questions. Much has to be done to build a consistent, practical and life cycle
science-based approach to product level sustainability information reporting
for all food, beverage, and agriculture products. Moreover, the data quality
of commercial databases for the agriculture and food systems remains, in our
opinion, quite poor, hence the strong need to improve the quantity and quality
of these databases.
In this chapter some of the typical methodological issues of agri-food LCA
are highlighted by showing, through case studies, how they have been treated
and managed. The starting point is the illustration of aspects regarding the
choice of the functional unit and system boundary definition. Following,
issues concerning the use of adequate fertilizer and pesticide dispersion models
are addressed. Next, different land use and water use assessment approaches
are analysed in relation to the agri-food sector. In the final part of the chapter
the current LCA approach used by the food industry are critically analysed.

7.2 Methodological Issues

7.2.1 Choice of Functional Unit
Choosing the functional unit is one of the very first critical tasks encountered
during an LCA. The choice of the functional unit may vary according to the
aim of the LCA study and may be determined in different terms such us func-
tionality, nutritional value, portion size or other criteria. A functional unit is
defined by the ISO 14044 norm as the "quantified performance of a product
system for use as a reference unit" (ISO-14044, 2006b). In addition, the ISO
14040 norm indicates that: "The functional unit defines the quantification of
the identified functions (performance characteristics) of the product. The pri-
mary purpose of a functional unit is to provide a reference to which the inputs
and outputs are related. This reference is necessary to ensure comparability of
LCA results. Comparability of LCA results is particularly critical when differ-
ent systems are being assessed, to ensure that such comparisons are made on
a common basis." (ISO-14040,2006a).
It is important to define a suitable functional unit since the choice of differ-
ent functional units is directly reflected on the results of the study which can
be completely contradictory (Hischier & Reichart, 2003; Kim & Dale, 2006).