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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
02 April 1991 to 30. April 1991 (start and end of experimental phase)
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: STP effluent
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Effluent of STP Wiesbaden (presumably a municipal STP, Germany.
- Laboratory culture: NA.
- Method of cultivation:NA.
- Storage conditions: No data.
- Storage length: No data.
- Preparation of inoculum for exposure: No data.
- Pretreatment: No data.
- Concentration of sludge: 1 mL effluent per 1 L inoculum.
- Initial cell/biomass concentration: No data.
- Water filtered: No data.
- Type and size of filter used, if any: No data.
Duration of test (contact time):
28 d
Initial conc.:
213 mg/L
Based on:
DOC
Initial conc.:
1.28 g/L
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium: Standard mineral medium.
- Additional substrate: No data.
- Solubilising agent (type and concentration if used): No data.
- Test temperature: No data.
- pH: No data.
- pH adjusted: No data.
- CEC (meq/100 g): No data.
- Aeration of dilution water: Yes.
- Suspended solids concentration: No data.
- Continuous darkness: No data.
- Other: -

TEST SYSTEM
- Culturing apparatus: no data.
- Number of culture flasks/concentration: 3 (one test concentration, one performance control, one blank control).
- Method used to create aerobic conditions: Aeration, air quality not specified.
- Method used to create anaerobic conditions: NA.
- Measuring equipment: DOC measurement with a Fa. Maihak UV-DOC.
- Test performed in closed vessels due to significant volatility of test substance: No data.
- Test performed in open system: No data. But presumably yes (aeration).
- Details of trap for CO2 and volatile organics if used: No data.
- Other: -

SAMPLING
- Sampling frequency: days 0 (3 hours), 1, 3, 6, 9, 13, 16, 20, 23, and 28.
- Sampling method: Removal of aliquots.
- Sterility check if applicable: No.
- Sample storage before analysis: No data.
- Other:

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, one replicate.
- Abiotic sterile control: No.
- Toxicity control: No.
- Procedural control: Yes, one replicate.
- Other: -

STATISTICAL METHODS: NA, since test systems were not replicated
Reference substance:
ethylene glycol
Key result
Parameter:
% degradation (DOC removal)
Value:
81
Sampling time:
28 d
Results with reference substance:
The reference substance was degraded within 28 days by 99%.
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The substance is readily biodegradable.
Executive summary:

In a non-GLP study according to OECD 301E the test item was aerobically exposed at 213 mg DOC/L to standard OECD mineral medium and an effluent of STP Wiesbaden (presumably municipal). Exposure was for 28 days. The above concentration of test substance was exposed to 1 mL effluent per 1 L standard mineral medium. Three test groups were incubated: Test item (213 mg DOC/L, one replicate), blank control (one replicate) and reference substance ethylene gylcol (one replicate). Biodegradation was determined on days 0 (3 hours), 1, 3, 6, 9, 13, 16, 20, 23, and 28 by measuring DOC with a Maihak DOC-UV device. The results show that 99 % of the reference substance was degraded within 23 days. A value for day 14 is not provided. Hence the validity of the test cannot be checked. Test items results show that 81% were eliminated within 28 days of which 70% were reached within 9 days and 10% within 3 hours. The results show that the substance is readily biodegradable.

 

Description of key information

The results of 2 experimental studies and the result of QSAR BIOWIN v4.10 modelling was used for the assessment of ready biodegradability of the substance. Experiments and calculation show that the substance is readily biodegradable. 

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

A valid non-GLP study (OECD 301 E, key study) shows that the substance is readily biodegradable, since 81% of the test substance were mineralized within 28 days of exposure to activated sludge (trigger for biodegradation is 60%). Another supporting experiment (non-GLP, OECD 301 D) shows mineralization of average 74% (mean of 81%, 67% and 74%) within 28 days (trigger for biodegradation is 60%). Ready biodegradation is supported by QSAR BIOWIN of EPI Suite which shows that the substance is readily biodegradable.