Page 225 - Materials Chemistry, Second Edition

4.4 Method of Impact Categories (Environmental Problem Fields) 209

Example 3: Ecotoxicity

Primary impact: Impact of pollutants on organisms, following the intake of the
pollutant or by a change of abiotic living conditions induced by the pollutant.
Secondary impact: Harmful impacts on single organisms, populations, species,
biocoenoses or ecosystems, impacts of transformation products and metabo-
lites of the pollutant.
Tertiary impacts: Harmful impacts on the level of ecosystems; drastic changes to
ecosystems, for example, by starvation of single species due to organ lesions,
but also by subtler impacts like, for example, the perturbation of chemical
communication systems or the hormone system; changes in biodiversity,
that is type and variety of species, changes in nutrition, nutrient cycles,
energy flows of ecosystems, and so on.
The primary impact of a pollutant following its intake by an organism is
linked to exposition. The bioconcentration factor (BCF) (C /
(pollutant X in the organism)
C ) is a useful indicator directly connected to expo-
(pollutant X in it the surrounding medium)
sition but does not allow a differentiation of the toxicological potentials of the
pollutants. Since the level of genuine importance for impact assessments – the
tertiary impacts – is however generally not retraceable to quantifiable single events,
substances are mostly assessed on the level of secondary impacts (usually level of
organisms, e.g. daphnia, fish and alga tests).
In a similar way all impact categories can be analysed. Noise can, for example,
be designated as an annoyance, but a chronic impact by noise may result in
psychological damage (continuous stress by traffic noise) or hearing defect. For
LCA it is important to realize that a mid-point quantification (closer to the inventory)
can be accomplished more easily, and the number of potential categories can be
reduced to a manageable quantity. Besides, indicators closer to the releases better
correspond to the precautionary principle since many of the possible subsequent
impacts are included in the assessment without detailed knowledge, which is often
not available, of causal chains. (see Figure 4.3).

4.4.3.2 Potential versus Actual Impacts
The approximately quantified effects in LCIA are usually considered as ‘potential’
impacts. 74) ISO 14040 (2006a), for example, says:

LCA addresses the environmental aspects and potential environmental impacts*
( … ) thoughout a product’s life cycle from raw material acquisition through
production, use, end-of-life treatment, recycling and final disposal (i.e. cradle to
grave).

74) Udo de Haes (1996), Heijungs and Guin´ ee (1993), ISO (2006a) and Finnveden et al. (2009).