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MARINE RISK ASSESSMENT
Table 31 Overview of P-assignment for different types of biodegradation data
Type of data Criterion Definitive assignment Screening assignment 1)
DT50 marine water > 60 d VP -
DT50 freshwater 2)
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> 40 d P 3) -
> 60 d VP -
DT50 marine sediment > 180 d VP -
DT50 freshwater sediment 2)
Readily biodegradable 4)
Inherently degradable
QSAR Non-linear model prediction <
0.5 or MITI non-linear model
prediction < 0.5 and Ultimate
biodegradation timeframe
prediction < 2.2
> 120 d P 3) -
> 180 d VP -
Yes Not P -
No - P or vP
Yes Not P 5) -
No - P or vP
- P or vP
1) These screening methods give an “open-ended” categorisation of the substance as either being potentially P or vP, which cannot easily
be related to a half-life for biodegradation.
2) Data for estuaries should also be considered in this category.
3) Half-life data in freshwater and freshwater sediment can be overruled by data obtained under marine conditions.
4) Regardless of whether the 10-d window criterion is fulfilled.
5) This only applies to cases where the specific criteria as mentioned in Section 4.4.3.3 are fulfilled.
4.4.4 Testing strategy for the B criterion
4.4.4.1 Introduction
Substances can accumulate in aquatic organisms directly from the water, i.e. bioconcentration, or
via uptake through the foodchain, i.e. biomagnification. A high bioaccumulation potential of a
substance is of particular concern for the marine environment due to the possible accumulation
in the foodchains and the potential long-term effects that may occur in organisms at the top of
these foodchains. Whereas different models and parameters are available to evaluate
bioconcentration for organic chemicals, suitable parameters to evaluate accumulation in marine
foodchains are not available. The bioconcentration factor (BCF) in aquatic organisms is
traditionally used as a first indicator for bioaccumulation (see Section 3.8.2).
In principle, the assessment of the (potential for) bioaccumulation in the context of the PBT
assessment makes use of measured bioconcentration factors in marine or freshwater organisms.
Where these are not available BCF values may be estimated from the octanol/water partition
coefficient (Kow) using QSAR models. In addition, Kow values, either experimentally
determined or estimated can be used directly to assess the potential for bioaccumulation.