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Input data
EFFECTS ASSESSMENT
The methods should be applied on all reliable available NOECs from chronic/long-term studies,
preferably on full life-cycle or multi-generation studies. NOECs are derived according to
previous considerations (Table 15).
Which taxonomic groups
It is important to include all available information on the mode of action of the chemical, in
order to evaluate the need to include possible other (sensitive) taxonomic groups or exclude
possible over-representation of certain taxonomic groups, realising that the mode of action may
differ between short-term effects and long-term effects and between taxonomic groups. The
minimum species requirements when using the Species Sensitivity Distribution method are:
• fish (species frequently tested include salmonids, minnows, bluegill sunfish, channel catfish,
etc.);
• a second family in the phylum Chordata (fish, amphibian, etc.);
• a crustacean (e.g. cladoceran, copepod, ostracod, isopod, amphipod, crayfish etc.);
• an insect (e.g. mayfly, dragonfly, damselfly, stonefly, caddisfly, mosquito, midge, etc.);
• a family in a phylum other than Arthropoda or Chordata (e.g. Rotifera, Annelida, Mollusca,
etc.);
• a family in any order of insect or any phylum not already represented;
• algae;
• higher plants.
It is recognised that for some of the taxa mentioned above, no internationally standardised test
guidelines for long-term tests are currently available. The applicability of existing test data and
the fulfilment of the above requirements thus need to be assessed on a case-by-case basis. There
is a need to evaluate additional information in order to assess how relevant and representative the
list of taxonomic groups is to the risk assessment scenario being investigated.
Minimal sample size (number of data)
Confidence can be associated with a PNEC derived by statistical extrapolation if the database
contains at least 10 NOECs (preferably more than 15) for different species covering at least
8 taxonomic groups.
Deviations from these recommendations can be made, on a case-by-case basis, through
consideration of sensitive endpoints, sensitive species, mode of toxic action and/or knowledge
from structure-activity considerations.
How to deal with multiple data for one species?
Where appropriate and possible, a pre-selection of the data should be performed in relation to
realistic environmental parameters for Europe (e.g. hardness of water, pH, organic matter and/or
temperature). The full database should be carefully evaluated to extract information (e.g., on
sensitive endpoints), which may be lost when “averaging” the data to a single value.
The test data applicable to the most sensitive endpoint should be taken as representative for the
species. In this context, demographic parameters can be used as endpoints, as can bio-markers if
they are toxicologically relevant in terms of population dynamics.
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