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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Administrative data

Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the substance is readily biodegradable
other:
Cross-reference
Reason / purpose:
data waiving: supporting information
Reference
Endpoint:
biodegradation in water: screening test, other
Remarks:
Seawater : Closed bottle
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 day
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Guideline study performed to GLP.
This study is known to be more stringent on assessment of biodegradation than screening studies using sewage treatment plant innoculum and a pass in this study is a good indicator of biodegradation potential.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 306 (Biodegradability in Seawater)
Version / remarks:
Closed bottle using natual seawater
Principles of method if other than guideline:
28 day closed-bottle test, using natural seawater.
The seawater was enhanced with trace elements and a low level of phosphates and checks made that microbial counts were within specification.
Nitrification inhibitors were added to prevent distortion of results from nitrate metabolism.
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Batch SRK 184/14
Purity 43%
clear yellow liquid
Oxygen conditions:
aerobic
Inoculum or test system:
natural water: marine
Details on inoculum:
Natural sea water, pH 7.9. Test performed at ca 20 C
The seawater was enhanced with trace elements and a low level of phosphates and checks made that microbial counts were within specification.
Nitrification inhibitors were added to prevent distortion of results from nitrate metabolism.
Duration of test (contact time):
28 d
Initial conc.:
2 mg/L
Based on:
formulation
Initial conc.:
ca. 0.9 mg/L
Based on:
act. ingr.
Parameter followed for biodegradation estimation:
DOC removal
Reference substance:
acetic acid, sodium salt
Parameter:
% degradation (DOC removal)
Value:
39
Sampling time:
6 d
Parameter:
% degradation (DOC removal)
Value:
55
Sampling time:
14 d
Parameter:
% degradation (DOC removal)
Value:
55
Sampling time:
20 d
Key result
Parameter:
% degradation (DOC removal)
Value:
61
Sampling time:
28 d
Details on results:
60% acheived over 28 days as percentage of ThOD
Results with reference substance:
Valid, with ca 100% degradation recorded
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable, but failing 10-day window
Conclusions:
The interprestion as 'readily biodegradable, but failing 10-day window' typically applies to sewage-based screening methods that are typically less difficult to pass. The sewater protocol has a very low microbial count to mimic the impact of spills in marine use.

Therefore a 'pass' in the marine assay is seen as a good indicator of rapid biodegradation in water treatment plants.
Executive summary:

Considered rapidly biodegradable for purposes of classification and is probably passing the 10 -day window if tested by sewage-system assays.

Data source

Materials and methods

Results and discussion

Applicant's summary and conclusion