Page 93 - Materials Chemistry, Second Edition

LIFE CYCLE IMPACT ASSESSMENT 75

to midpoint modeling. Other more heterogeneous impact categories, such as
"Human Toxicity" and "Ecotoxicity Effects," do not fit well into a single mid-
point and, in effect, approach the AoPs.
The Life Cycle Initiative, a joint project between the United Nations
Environment Programme (UNEP) and the Society for Environmental
Toxicology and Chemistry (SETAC) propose a comprehensive LCA frame-
work that combines midpoint-oriented and damage-oriented approaches in a
common and consistent framework (Jolliet et ah, 2004). While elaborating the
guidance of recommended practices in LCIA, (Margni, Gloria et ah 2008) pro-
vide a detailed discussion on the choice of midpoint and damage indicators.
Jolliet et al. (2004) and Bare and Gloria (2006) propose dividing impact cat-
egories into two groups: (1) Those based on common impact mechanisms
and (2) Those that may not have a common midpoint and are comprised of
different environmental mechanisms.
The first group includes relatively well-established midpoints (global
warming and ozone depletion) based on common impact mechanisms and for
which further modeling does not differentiate between various substances.
This type of impact categories is illustrated in Figure 4.4. Examples of
the first type of traditional midpoint categories include: ozone deple-
tion, global warming, acidification, eutrophication, and smog formation.

Endpoint effects
not calculated or
which do not
[ all calculated endpoint effects indicators are
DAMAGE indicator may aggregate
have damage
into single unit.
lost
Figure 4.4 Impact models progresses from inventory flow to damage for classic midpoint
impact categories. Note that endpoints that are not modeled are lost (Bare and Gloria 2006).