Page 193 - Materials Chemistry, Second Edition

10 Life Cycle Impact Assessment 179

• Exposure: change in available quantity, quality or functionality of a resource
and potential competition among several users (human or ecosystems, with
different degrees of ability to adapt and/or compensate), e.g. habitat loss,
dehydration stress, soil biotic productivity, etc.
• Effects: adverse effects on directly affected users that are unable to adapt or
compensate (e.g. diseases due to lower water quality, migration or death of
species due to lack of water or habitat, malnutrition, etc.) and contributions to
other impact pathways (e.g. global warming due to change in soil albedo or
released soil carbon)
• Damage: distinguishing the severity of observed effects by quantifying the
reduction of biodiversity, or human health of a population affected (although not
yet common practice, this may even go as far as including social effects such as
war on water access)

This mechanism will have specific features and may vary significantly between
impact categories, but the principle remains valid for all extraction-related impact
categories, currently being:
• Land Use (affecting biotic productivity, aquifer recharge, carbon sequestration,
albedo, erosion, mechanical and chemical filtration capacity, biodiversity, etc.)
• Water use (affecting human health, aquatic ecosystems, terrestrial ecosystems)
• Abiotic resource use (fossil and mineral) affecting the future availability of the
non-renewable abiotic resources
• Biotic resource use (e.g. fishing or wood logging) affecting the future avail-
ability of the renewable biotic resources and the ecosystems from which they are
harvested.

10.2.3.5 The Impact Indicator

The starting point of the environmental mechanism is set by an environmental
intervention in the form of an elementary flow in the LCI, and the contribution from
the LCI flow is measured by the ability to affect an indicator for the impact category
which is selected along the cause–effect chain of the impact category. Apart from
the feasibility of modelling the indicator, this selection should be guided by the
environmental relevance of the indicator. For example, there is limited relevance in
choosing human exposure to the substance as an indicator for its human health
impacts, because even if a substance is taken in by a population (i.e. exposure can
be observed and quantified), it might not cause any health effect due to a low
toxicity of the substance, and this would be ignored if a purely exposure-based
indicator was chosen. In general, the further down the cause–effect chain an indi-
cator is chosen, the more environmental relevance (and meaning) it will have.
However, at the same time the level of model and parameter uncertainty may
increase further down the cause–effect chain, while measurability decreases (and
hence the possibility to evaluate and check the result against observations that can be