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:
9 September 1992 - 7 October 1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study has been performed according to OECD and/or EC guidelines and according to GLP principles. Limited information available to verify the composition of the used test substance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report Date:
1992

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
(1981)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): KY-ET
- Substance type: light yellow solid
- Physical state: solid
- Stability under test conditions: stable at least 48 hours in water
- Storage condition of test material: RT in the dark

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Municiple sewage treatment plant Waterschap de Aa, Schijndel, The Netherlands
- Preparation of inoculum for exposure: The activated sludge was aerated for 4 hours aeration. After 0.5 hours settling, the supernatant was decanted to provide a significantly large volume for a 1% inoculum for each test flask
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
10 mg/L
Based on:
test mat.
Initial conc.:
20 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Test temperature: The temperature varied between 18.5 and 21.5 degrees Celsius, except for day 0 when the medium temperature was 17 degrees Celsius
- pH: 4.8-5.5
- pH adjusted: no
- Continuous darkness: yes - brown vessels

TEST SYSTEM
- Number of culture flasks/concentration: 1
- Test performed in closed vessels due to significant volatility of test substance:
- Details of trap for CO2 and volatile organics if used: barium hydroxide (CO2 produced in each bottle reacted with the barium hydroxide in the gas scrubbing bottle and precipitated out as barium carbonate; amount of CO2 produced was determined by titrating the remaining Ba(OH)2 with 0.05 N standardized HCl.

SAMPLING
- Sampling frequency: d2, 5, 7, 9, 12, 16, 21 and 28
Reference substance
Reference substance:
other: sodium acetate

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (CO2 evolution)
Value:
13
Sampling time:
28 d
Remarks on result:
other: concentration 10 mg/l
Parameter:
% degradation (CO2 evolution)
Value:
6
Sampling time:
28 d
Remarks on result:
other: concentration 20 mg/L
Details on results:
Based on the calculated ThCO2 for the test substance, only 13% and 6% biodegradation, respectively for the low (10mg/L) and high (20 mg/L) nominal test concentrations, was observed. Therefore KY-ET was judged not readily biodegradable.

BOD5 / COD results

Results with reference substance:
The reference substance was biodegraded more than 60% (62%) within 12 days and was degraded to 97% by the end of the testing period (28d). The total CO2 release within the blank was 9.4 mg CO2.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
other: under test conditions little biodegradation observed
Conclusions:
Under the conditions of the test KY-ET was not readily biodegradable.
Executive summary:

A Modified Sturm Test (CO2 evolution) was performed according to OECD 301B. There were no protocol or other deviations and the data was judged reliable. The nominal concentrations of 10 mg/L and 20 mg/L showed only 13% and 9% degradation, respectively, via CO2 evolution. Therefore the test substance was judged not readily biodegradable.