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

MARINE RISK ASSESSMENT
• when a substance does not fulfil the criteria for ready biodegradability as defined in sections
on biodegradation and for the marine ready test (see Sections 2.3.6 and 4.2.3.4), it is
considered as being potentially persistent. The 10-day window criterion should not be used
here as an additional criterion. If the substance fulfils the criteria for B and T, further testing
is needed. It must be noted that in this case it is not considered appropriate to perform
inherent biodegradability tests but rather to go directly to simulation testing;
• when results are available showing that a substance does not fulfil the criteria for inherent
biodegradability as defined within the Annex V method or the OECD guideline this is a
clear indication that the substance will not biodegrade in the marine environment either. The
substance will be regarded as potentially persistent. When the (screening) criteria for B and
T are also fulfilled, further testing is needed in order to determine the half-life in the
environment.
• when a substance passes the criteria for inherent biodegradability tests this does not
necessarily indicate that it will not be persistent under environmental conditions. However,
in order to make the best use of available information it is accepted to use the results of two
specific tests when they fulfil certain criteria as an indication that the substance is not
persistent. These test are:
- Zahn-Wellens Test (EU Annex V C.9, OECD 302B, 1992g): Pass level (70%
mineralisation) must be reached within 7 days, log-phase should be no longer than 3
days, percentage removal in the test before degradation occurs should be below 15%,
not tested with pre-adapted microorganisms;
- MITI II -test (OECD 302C, 1981d): Pass level must be reached within 14 days; logphase
should be no longer than 3 days, not tested with pre-adapted microorganisms.
In case a range of biodegradation data, including conflicting data, is available, a case-by-case
assessment is needed, using a weight of evidence approach, in order to decide whether a
substance has the potential to be persistent (see also Section 2.3.6).
4.4.3.4 Data from biodegradation estimation models
For new substances, priority existing substances and biocides, information from a ready
biodegradability test is normally available and therefore an initial decision whether the substance
is potentially persistent can be taken. However, for many other substances no data will be
available or the available information is difficult to interpret. For these substances it can be
helpful to apply models that estimate the potential for biodegradation in the environment.
In a preliminary assessment whether a substance has a potential for persistence in the marine
environment and hence for asking for actual test data it is proposed to consider use of the
BIOWIN program. This program estimates aerobic biodegradability of organic chemicals using
6 different models:
1. linear model,
2. non-linear model,
3. ultimate biodegradability timeframe model,
4. primary biodegradability timeframe model,
5. MITI linear model,
6. MITI non-linear model;
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