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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report date:
2002

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid: viscous
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Purity : 96.8%

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
Aerobic activated sludge from a wastewater treatment plant treating predominantly domestic wastewater. The sludge was washed twice with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension was weighed, therafter dried and the ration of wet to dry weight was calculated.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Details on study design:
Temperature: 22°C
Light regimen: darkness
pH at the start of the test: 7.2-7.4
pH at the end of the test: 7.1-7.8
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Key result
Parameter:
% degradation (O2 consumption)
Value:
< 60
Sampling time:
28 d
Details on results:
The biodegradation of the test item was calculated based on the theoretical oxygen demand (ThOD) of 2.54 mg O2/mg test item.
In one of the two flask of each test with the test item the biochemical oxygen demand (BOD) in the test media increased significantly after 11-13 days until test termination after 28 days. At the end of the 28-day exposure period, the biodegradation rate of allethrin was 37 (test I) and 61% (test II), respectively.
In the second flask from test II the BOD in the test medium increased starting on Day 26, reaching a biodegradation rate of 14% at Day 28. Only in one flask, no increase of the BOD was observed.
In no case, the pass level for ready biodegradability, i.e. a biodegradation rate of at least 60% of the ThOD in a 10-day window within the 28-day period of the test, was reached.

BOD5 / COD results

Results with reference substance:
The reference item was degraded by an average of 86-89% by exposure Day 14. At day 28, the reference item was degraded by an average of 92%.

Any other information on results incl. tables

The test item had no inhibitory effect on activated sludge microorganisms (biodegradation rate in both toxicity controls was >25% within 14 days) .

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The mean degradation rate (calculated as average over the degradation rates in all test vessels) was 28%. Allethrin was found to be not ready biodegradable under the test conditions within 28 days.