ILCD Handbook: Framework and requirements for LCIA models and ...

ILCD Handbook: Framework and requirements for LCIA models and indicators First edition
4.3 Human toxicity
4.3.1 Framework and scope
Models and factors for toxicological effects in LCA must be based on the relative risk and
associated consequences of chemicals that are released into the environment. These must
build on the principles of comparative risk assessment, while providing indicators linked to
the Area of Protection ‗Human Health‘ (see Chapter 2).
LCA characterisation models and factors for toxic effects must rely on models that
account for a chemical‘s fate in the environment, human exposure, and differences in
toxicological response (both likelihood of effects and severity).
The scope and methodology of an LCA differs from that of many approaches adopted for
toxicological assessments in a regulatory context. Regulatory assessments of chemical
emissions usually have the objective of evaluating whether there will be an unacceptable risk
of a toxicological effect to an individual or subpopulation.
The focus in regulatory assessments is generally on ensuring that policy-based limits are
not surpassed by exposures at any location or point in time. For example, the maximum
likely exposure in the region of an emission may be compared to a tolerable threshold. If this
exposure is less than the agreed threshold then no further action is likely to be necessary
from a regulatory perspective. It should be noted that these regulatory limits, for example for
cancer effects, do not necessarily reflect an absence of an effect and neither are they
generally suitable for use in comparative risk assessments where one emission has to be
compared against another.
Nevertheless, the underlying mass balance models and basic dose-response information
used to determine comparative estimates for LCA are often the same as for regulatory
approaches. A key difference is that LCIA takes into account all releases of all substances
with a toxicity potential due to the evaluated product over the entire life cycle, regardless of
where and when they are released. However, in LCIA all emissions not related to the
evaluated product are deliberately excluded from the assessment, e.g. emission of the same
chemicals from other products or from sites unrelated to the product. Thus, site specific
regulatory assessments, chemical related regulatory assessments and toxicity aspects in
LCIA are to be seen complementary in their nature.
Life cycle assessments provide insights for products that are complementary to those of
many regulatory risk assessments. In LCA it is desirable to account for the full extent of the
likelihood of an effect (recommended midpoint indicator basis) and differences in severity
(recommended endpoint indicator basis).
The basis of comparative risk in LCA is the entire global population, using best-estimates
complemented with uncertainty insights. The factors must reflect the likelihood of a
toxicological impact integrated over time and space that is associated with the release of a
quantity of chemical into the environment. This is a fundamental difference from many
regulatory approaches, which focus more on realistic peak exposures for individuals
compared to acceptable thresholds. Nevertheless, this basis is consistent with the principles
already adopted for the assessment of substances such as radionuclides, for other impact
categories in LCA such as climate change, as well as in approaches necessary to support
cost-benefit analyses.
Contributions of emissions to short-term/acute and local scale effects are presently not
addressed in the recommendation. This includes those associated with indoor exposures,
direct exposure to products during their use stage, and to exposures in the work place. The
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