Page 301 - Materials Chemistry, Second Edition

4.5 Impact Categories, Impact Indicators and Characterisation Factors 285

extend over a range of ten orders of magnitude which is why a classification by an
order of magnitude of the individual values is judged as being sufficient and the
deviations of the individual models from each other (to maximally three orders of
magnitude) are regarded as tolerable.
A restriction of the model according to the authors (Rosenbaum et al., 2008, loc.
cit.) is the modelling of oceans as sinks, and ecotoxicity only referring to fresh water
organisms. Moreover, averaged sensitivities of tested groups of organism, not those
of the most sensitive species are integrated into the determination of the effect
factors. This procedure is justified, however, by the fact that in LCA – contrary to
chemical risk assessment – no risk is measured but comparative statements are to
be made. 343) Thus, average values are more useful than extrema.
A comprehensive treatment of USEtox including examples from the praxis of
LCIA is now available (special issue of The International Journal Life Cycle Assess.
edited by Jørgensen and Hauschild (2011, loc. cit.). The model developed for the
purpose of LCIA (as opposed to chemical risk assessment) has been described
earlier by Hauschild. 344)

4.5.3.4 Concluding Remark on the Toxicity Categories
For toxicity-related impact categories, like for all others, the inclusion of these
categories into the impact assessment has to be announced in ‘Goal and Scope’
and the method used has to be defined. Surely, LCAs on chemicals as such or as a
substantial part of products, for example, detergents, drugs, solvents, agricultural
chemicals, and so on must address those two impact categories, human toxicity and
ecotoxicity, in order to give convincing and credible results. Besides, simpler impact
indicators can further be employed for materials or products where chemicals are
only released in small quantities into the environment. This is not the case if the
use phase is dominated by cleansing or maintenance.
For procedures including persistence and long-range transfer, great progress has
been made in recent years and more is to be expected (For a recent survey see. 345)
Toxicological data like, for example, no observed effect level (NOEL) or NOEC and
derived values are, however, always at the basis to span a first relative scale.
A systematic inclusion of human toxicity and ecotoxicity into the impact assess-
ment increases requirements in the inventory:
1. The table of emissions should list as many individual chemicals as possible.
2. Data should not only include generic data records on energy and transportation
processes but be determined by a careful specific process analyses.
3. Data asymmetries (particularly frequent within toxicity) must be avoided in
comparative LCAs.
Data asymmetries within these impact categories can result in gross false esti-
mations because human and ecotoxicity of chemicals covers a range of many
orders of magnitude. Thus a particularly ‘poisonous’ substance may even though

343) Larsen and Hauschild (2007a,b).
344) Hauschild et al. (2008).
345) Kl¨ opffer (2012b)