technical guidance documents - Institute for Health and Consumer ...

TESTING STRATEGIES
Another possible option for the refinement of the PEC is the performance of simple monitoring
(for example at point of release or in predicted worst-case environments). Long-term monitoring
programmes should only be initiated:
• in the case of borderline risk assessments, where immediate risk reduction action cannot be
justified;
• as a means of checking the effectiveness of risk reduction action;
taking into account monitoring programmes established under other EU legislation.
6.2.1 Aquatic compartment
In the following, a biodegradation testing strategy for the aquatic environment is presented in
relation to standardised testing methods available (see also Sections 2.3.6 and 4.2.3).
However, it should also be considered at each stage whether further abiotic testing, e.g. direct or
indirect aquatic photolysis or a, full adsorption/desorption test, could refine the PEC (local or
regional). In that respect it has to be considered whether the photolytic or hydrolytic degradation
products themselves may constitute a risk, and it should be considered to determine the ultimate
degradation half-life of these degradation products.
Two cases can be distinguished:
PEC/PNEC > 1 and the substance is readily biodegradable
Further biotic testing is unlikely to affect the PEC, unless the producer/importer believes it is
worth conducting a simulation test, which may generate a removal percentage greater than that
assumed for readily biodegradable substances.
PEC/PNEC > 1 and the substance is not readily biodegradable
If the substance is inhibitory at a level below that used in the ready test, an STP simulation test
that measures ultimate degradation should be performed at a non-inhibitory concentration. This
will only help refine PEClocal if the concentration predicted in the sewage treatment plant is
below the inhibition threshold.
Simulation tests for surface water and/or aquatic sediments may be needed to refine the PECs for
surface water and/or sediment for the regional assessment. Internationally standardised methods
have recently been developed and should be used for this purpose (see Section 2.3.6). The results
from such testing can be used directly in the calculation of PEC for the system being simulated.
Care will need to be taken, however, that the conditions of the test substance concentration
reflect those likely to be found in the relevant compartment (STP, surface water, sediment and/or
soil) so that the degradation half-life for full mineralisation can be established. For slowly
degrading substances it is in general recommended that any metabolites/degradation products are
identified and that their mineralisation half-lives are also established.
In deciding whether there is a need for further simulation degradation studies in one or more of
the environmental compartments surface water (freshwater, marine water) and/or sediment it
should be considered how a more precisely determined half-life for that compartment might
influence the overall risk assessment of the substances. This should be done by taking into
account the current production, use and environmental release and distribution of the substance.
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