Page 295 - Materials Chemistry, Second Edition

4.5 Impact Categories, Impact Indicators and Characterisation Factors 279

strictly speaking, false 322) assumptions of a linear dose-response relationship for all
types of toxic impacts. This results in a toxicity factor of approximately 0.5/ED 50
for every disease endpoint and intake pathway, where ED 50 refers to a daily dose
causing an effect with a probability of 50% of human life time. Up to four EFs are
calculated:
• Cancer by intake exposure
• No cancer illness by intake exposure
• Cancer by inhalation exposure
• No cancer illness by inhalation exposure.
The human toxicity factors are of dimension comparative toxic units for human
health (CTU ) or number of diseases/kilgram substance intake. A reference to
h
mass ensures a linkage to released quantities of a substance and to the fU. Since
calculations can be automated with the help of software and integrated databases,
the focus shifts towards the inventory, which by then should also include emissions
of a multitude of organic substances. In the most recent data set, over 3000 organic
chemicals are included (2500 with freshwater EFs). For ‘metals’ (mostly ionic),
dissociating organic compounds and amphoteric compounds (e.g. surfactants)
only interim characterisation factors, 323) have been determined since their fate
factors are usually difficult to calculate by multimedia models. 324)
The toxicological information needed for the determination of the ED -values
50
was taken from extensive data collections, for example, US EPA. The same is valid
for the physico-chemical data of the compounds necessary for the computation.
Detailed information necessary for a practical application of this methodology
can be obtained in the USEtox special issue 325) including both human toxicity and
ecotoxicity (next section).

4.5.3.3 Ecotoxicity

4.5.3.3.1 Protected Objects Some problems of the impact category ‘ecotoxic-
ity’ have already been addressed within the category human toxicity. Protected
objects in the category ecotoxicity are primarily ecosystems, from small-scale
ecosystems to the macro ecosystem Earth including the atmosphere (Lovelock’s
‘Gaia’). 326) Interdependence between biotic and abiotic factors within the complex
structure of producers, consumers, decomposers and the physical environment
is typical of ecosystems. Biotic factors are organisms at various trophic levels.
Usually primary producers, consumers and destructors are differentiated. From
dead biomass the destructors generate nutrients which are needed by producers.

322) A more realistic assumption would make a reference to the functional unit, necessary for LCA,
impossible.
323) Henderson et al. (2011).
324) Classical multi-media models were developed for non-dissociating organic molecules without a
surface-active impact, see Mackay (1991) and Kl¨ opffer (1996b, 2012b).
325) Jørgensen and Hauschild (2011).
326) Gaia was the old (pre-olympic) earth goddess and primeval mother, earth itself; Lovelock (1982,
1990).