Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
23 October 2000 - 22 November 2000
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

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

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Specific details on test material used for the study:
Test material: Fenitrothion (Batch No.: 00611G, Purity: 94.6%)
Reference material: Sodium benzoate (Batch No.: 403453/1, Purity: 99.6%)

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, adapted
Details on inoculum:
aerobic activated sludge from a wastewater treatment plant treating predominantly domestic wastewater. The diluted activated sludge was used as inoculum to give a final concentration of 30 mg dry weight material per liter
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
other: guideline
Remarks:
This test design was selected according to the guidelines since the test item is not completely soluble at a concentration of 100 mg/l (information from the e-Pesticide Manual, Eleventh Edition, Version 1.1).
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
other:
Remarks:
The percentages of biodegradation of fenitrothion and sodium benzoate (the reference material) are calculated based on the biochemical oxygen demand (BOD) and the theoretical oxygen demand (ThOD)
Details on study design:
The reference material was tested simultaneously under the same conditions as the test material as a procedure control. Also the combination of the test material and the reference material was tested as a toxicity control. The test flasks were incubated under continuous stirring at 22°C for 28 days. Oxygen consumption was recorded manually by taking a daily reading at least each working day.
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Key result
Parameter:
other: % biodegradation based on ThOD NH4
Value:
6
Sampling time:
28 d
Remarks on result:
other: not readily biodegradable
Key result
Parameter:
other: % biodegradation based on ThOD NHO3
Value:
5
Sampling time:
28 d
Remarks on result:
other: not readily biodegradable

BOD5 / COD results

BOD5 / CODopen allclose all
Key result
Parameter:
ThOD
Value:
133 other: mg O2/L test soln. ThOD NH4
Key result
Parameter:
ThOD
Value:
156 other: mg O2/L test soln. ThOD NO3
Results with reference substance:
Percentage biodegradation of the reference material (Procedure control: Na-benzoate):
Base don ThOD: 87%

Any other information on results incl. tables

Percentage biodegradation of Fenitrothion

based on ThODNH4

based on ThODNO3

n=1

n=2

n=1

n=2

4

8

4

7

6 (mean)

5 (mean)

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Fenitrothion is concluded to be not readily biodegradable under the conditions tested.