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RISK CHARACTERISATION
If a refinement of the risk characterisation is possible but the necessary data are not available,
further information and/or testing needs to be requested. On a case-by-case basis, a decision
must be taken as to whether both the PEC and PNEC will be revised or only one of them.
Consideration should be given to which of the parameters that will be most sensitive to revision
as a result of further testing. The decision by the competent authority to request additional data
should be transparent and justified and should be based on the principles of lowest cost and
effort, highest gain of information and the avoidance of unnecessary testing on animals. This
iterative approach has precautionary aspects as data gaps are filled by worst-case assumptions or
high assessment factors. Guidance on which tests to conduct and how the results of such tests
can be used to revise the PEC and/or the PNEC is given in Sections 6.2 and 6.3 of this document.
Detailed guidance on how to use (Q)SARs in order to clarify whether further testing is
necessary, and how these (Q)SARs can assist in deciding on the testing strategy, is given in
Chapter 4 (Use of QSARs).
5.3 RISK CHARACTERISATION FOR EXISTING SUBSTANCES
The environmental risk assessment in the context of article 5 and Annex 3 of Regulation 1488/94
involves the comparison of the PEC and PNEC values for the different endpoints mentioned
above. Regulation 793/93 mentions three different conclusions that may apply on the basis of the
risk characterisation:
Conclusion (i) There is need for further information and/or testing;
Conclusion (ii) There is at present no need for further information and/or testing and no need
for risk reduction measures beyond those which are being applied already;
Conclusion (iii) There is a need for limiting the risks; risk reduction measures which are
already being applied shall be taken into account.
The general scheme given in Figure 17 applies for the risk characterisation of existing
substances. At the first comparison of the PEC and PNEC values it is assumed that industry is
contacted and that all available information is used to derive these. If the PEC/PNEC ratio is
found to be less than or equal to one for each compartment, conclusion (ii) shall apply. If the
PEC/PNEC ratio for any compartment is greater than one, the rapporteur shall judge whether
further information and/or testing are required to clarify the concern (conclusion (i)) or if
(further) risk reduction measures are necessary (conclusion (iii)). The judgement shall be carried
out on the basis of the size of the PEC/PNEC ratio and some additional indicators such as:
1. indications of bioaccumulation potential;
2. the shape of the toxicity/time curve in ecotoxicity testing;
3. indications of other adverse effects on the basis of toxicity studies, e.g. classification as a
mutagen, toxic or very toxic or as harmful with a risk phrase R40 (“Possible risk of
irreversible effects”) or R48 (“Danger of serious damage to health by prolonged exposure”);
4. data on structurally analogous substances.
Furthermore indications of other adverse effects, e.g. classification with the risk phrases R45
(“May cause cancer”), R46 (“May cause heritable genetic damage”), R47 (“May cause birth
defects”) and R60 (“May impair fertility”) may be considered as well.
These factors especially pertain to substances for which a “standard” risk assessment cannot be
performed, for instance because the models that are applied are not suitable, or for substances for
which the standard data set does not give suitable information on the properties of the substance
(for instance highly hydrophobic substances that do not show any toxicity in short-term tests).
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