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

ILCD Handbook: Framework and requirements for LCIA models and indicators First edition
consideration of safety factors only as part of the uncertainty assessment, and not as an
integral part of the toxicological effects data.
Due to the large number of potential endpoints that involve various mechanisms, there is
no true midpoint for toxicological effects where comparisons can be made on a purely natural
science basis. The midpoint indicator is therefore based on the likelihood of an effect
associated with an emission of a quantity of a chemical.
Though each toxicological effect could be treated as a separate endpoint, these effects are
usually grouped for practical reasons in subcategories. Subcategories include:
Cancer.
Respiratory diseases.
Other non cancer effects.
Impact of ionizing radiation.
The severity factor to account for differences in the effects can be estimated by implicitly
assuming equal weighting within these categories or by using explicit metrics such as Years
of Life Lost (YLL) and Years of Life Disabled (YLD) as discussed in Chapter 3 for Human
Health.
4.3.2 Criteria for Evaluation of this impact category
In addition to the general criteria described in Chapter 2, the main criteria ‗Environmental
relevance‘ and ‗scientific robustness‘ are further specified by the following sub criteria:
For environmental relevance, criteria have been defined to assess the quality and
adequacy of the assessment framework:
The model considers fate, exposure and effects in a quantitative way. Fate factors,
intake fraction and dose-response information can be given as intermediary results.
Urban area is considered separately. Advection out of a region or from a continent, for
example, is not considered a final loss.
Influential fate processes are taken into account as appropriate (e.g. –degradation,
chemical reaction, volatilization, deposition, intermittent rain, direct deposition of
pesticides on plants, colloid matter, sedimentation).
Main impact pathways are covered as being relevant (inhalation, ingestion of meat,
dairy products, fish, eggs, etc).
Regarding dose-response, the Effect Dose 10% (ED10) or 50% (ED50) is used as a
benchmark for the point of departure, avoiding safety factors. If not available
extrapolation from NOAEL to LOAEL (No or Lowest Observable Adverse Effect Levels)
is performed. Human data are preferably used when test sample sizes are sufficient
and a causal relationship is proven.
Chemicals that test negative in cancer tests are differentiated from chemicals without
available data.
Route to route extrapolation (e.g. oral to inhalation) methods are available for chemicals
with partial data.
Regarding severity and aggregation, value judgments are transparent and intermediary
results are kept separate.
4 Requirements for specific impact categories 40