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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
Study period:
18 January 2012 to 16 February 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Deviations:
no
Qualifier:
according to
Guideline:
ISO DIS 9439 (Ultimate Aerobic Biodegradability - Method by Analysis of Released Carbon Dioxide)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Identification: Paz-E
- Molecular formula: C44H48O4N8F2
- Molecular weight: 790.9
- Description: White powder

- Test substance storage: At room temperature protected from light in desiccator
- Stability under storage conditions: Stable
- Expiry date: 25 November 2012 (allocated by NOTOX, 1 year after receipt of the test substance)

- Hygroscopic: Yes, in desiccator
- Volatile: No
- Test substance handling: Use amber-coloured glassware or wrap container in tin-foil.
- Stability in water: Unknown
- Solubility in water: <10 mg/mL

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Source: The source of test organisms was activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.

Treatment: The freshly obtained sludge was kept under continuous aeration until further treatment. The concentration of suspended solids was 4.7 g/l in the concentrated sludge (information obtained from the municipal sewage treatment plant). Before use, the sludge was allowed to settle (58 minutes) and the supernatant liquid was used as inoculum at the amount of 10 ml/l of mineral medium.
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
18 mg/L
Based on:
test mat.
Initial conc.:
12 mg/L
Based on:
other: Total Organic Carbon (TOC)
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (CO2 evolution)
Value:
25
Sampling time:
29 d
Remarks on result:
other: HCl added on the 28th day (last CO2-measurement on the 29th day)
Parameter:
% degradation (CO2 evolution)
Value:
10
Sampling time:
29 d
Remarks on result:
other: HCl added on the 28th day (last CO2-measurement on the 29th day)
Details on results:
The relative biodegradation values calculated from the measurements performed during the test period revealed 25 and 10% biodegradation of Paz-E, for the duplicate bottles tested. Thus, the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met.

In the toxicity control more than 25% biodegradation occurred within 14 days (34%, based on ThCO2). Therefore, the test substance was assumed not to inhibit microbial activity.

BOD5 / COD results

Results with reference substance:
The positive control substance was biodegraded by at least 60% (75%) within 14 days.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable (25-10%)
Conclusions:
PAZ-E was not readily biodegradable under the conditions of the modified Sturm test presently performed.