Page 86 - Materials Chemistry, Second Edition

68 LIFE CYCLE ASSESSMENT HANDBOOK

health and the environment than another. Also, with varying sites where the
release occurs, an amount of one pollutant can have different effects under dif-
ferent condition.
The life cycle impact assessment (LCIA) phase of an LCA is the evaluation of
potential human health and environmental impacts of the natural resources and
environmental releases identified during the inventory. By modeling poten-
tial impact pathways, LCIA addresses ecological and human health effects, as
well as resource depletion, in order to help us better understand the linkage
between the product or process and its potential environmental impacts. An
important distinction exists between LCIA and other types of impact analysis
(see box). LCIA does not necessarily attempt to quantify site-specific or actual
impacts associated with a product, process, or activity. That is, LCIA does not
attempt to directly assess the impact of releases as a traditional risk assess-
ment would. According to the US Environmental Protection Agency (EPA),
"Risk assessment is a process in which information is analyzed to deter-
mine if an environmental hazard might cause harm to exposed persons and
ecosystems (EPA 2004)."

Box 4.1 LCA versus Risk Assessment (EPA 2006)

"An important distinction exists between life cycle impact assessment
(LCIA) and other types of impact analysis. LCIA does not necessarily
attempt to quantify any specific actual impacts associated with a product,
process, or activity. Instead, it seeks to establish a linkage between a system
and potential impacts. The models used within LCIA are often derived and
simplified versions of more sophisticated models within each of the various
impact categories. These simplified models are suitable for relative compar-
isons of the potential to cause human or environmental damage, but are not
indicators of absolute risk or actual damage to human health or the envi-
ronment. For example, risk assessments are often very narrowly focused
on a single chemical at a very specific location. In the case of a traditional
risk assessment, it is possible to conduct very detailed modeling of the
predicted impacts of the chemical on the population exposed and even to
predict the probability of the population being impacted by the emission. In
the case of LCIA, hundreds of chemical emissions (and resource Stressors)
which are occurring at various locations are evaluated for their potential
impacts in multiple impact categories. The sheer number of Stressors being
evaluated, the variety of locations, and the diversity of impact categories
makes it impossible to conduct the assessment at the same level of rigor
as a traditional risk assessment. Instead, LCIA models are based on the
accepted models within each of the impact categories using assumptions
and default values as necessary. The resulting models that are used within
LCIA are suitable for relative comparisons, but not sufficient for absolute
predictions of risk."