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:
Preliminary COD determination 2005-09-21. Study test phase 2005-09-23 to 2005-10-21. Study report signed 2006-01-26.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Meets the criteria for classification as Reliable without restriction according to Klimisch et al (1997)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report Date:
2006

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: Final effluent stage from Severn Trent Water plc sewage treatment plant at Loughborough, Leceistershire, UK
- Storage conditions: The effluent was filtered through coarse filter paper and the filtrate maintained on continuous aeration at 21 deg. C
- Concentration of sludge: Test media was innoculated with sewage treatment micro-organisms at 1 drop of innoculum per litre
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
5 mg/L
Based on:
act. ingr.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: The culture medium used in this study was that recommended in the OECD guidelines.
- Test temperature: 20 deg. C

TEST SYSTEM
- Number of culture flasks/concentration: Sufficient bottles were prepared to allow a single oxygen determination per bottle with duplicate bottles for each test medium at each sampling point.
- Measuring equipment: Dissolved oxygen determined using a YSI 54A dissolved oxygen meter and BOD probe.

SAMPLING
- Sampling frequency: Dissolved Oxygen concentrations for each test medium were determined on days 0, 3, 5, 7, 11, 14, 18, 21, 24 and 28.

CONTROL AND BLANK SYSTEM
- Inoculum blank: A control consisting of inoculated culture medium
- Toxicity control: The test substance (5.0 mg ai/l) plus the standard reference material (1.5mg/l sodium benzoate) in inoculated culture medium
Reference substance
Reference substance:
benzoic acid, sodium salt
Remarks:
3.0 mg ai/l

Results and discussion

Preliminary study:
The COD of the test substance was determined to be 1.27 mgO2/mg.
% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
7
Sampling time:
5 d
Parameter:
% degradation (O2 consumption)
Value:
11
Sampling time:
7 d
Parameter:
% degradation (O2 consumption)
Value:
11
Sampling time:
14 d
Parameter:
% degradation (O2 consumption)
Value:
11
Sampling time:
21 d
Parameter:
% degradation (O2 consumption)
Value:
11
Sampling time:
28 d

BOD5 / COD results

Results with reference substance:
Sodium benzoate attained 80% degradation after 14 days and 82% degradation after 28 days thereby confirming the suitability of the test method and culture conditions.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable
Conclusions:
It is concluded that in this study the test substance failed to meet the criteria for ready biodegradability.
Executive summary:

Introduction

This study was performed to assess the ready biodegradability of the test substance in an aerobic aqueous medium. The method was designed to be compatible with the following guidelines:

OECD Guidelines for Testing of Chemicals (1992) No. 301D, 'Reday Biodegradability; Closed Bottle Test'

Method C.4 -E of Commission Directive 92/69/EEC (Annex V of Council Directive 67/548/EEC)

US EPA Fate, Transport and Transformation Test Guidelines OPPTS 835.3110 Paragraph (o).

Results & Conclusions

The test substance attained 11% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the terms and conditions of OECD Guideline No 301D.