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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Guideline study to GLP standards with no deviations

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Specific details on test material used for the study:
Source and lot/batch number of test material:
Thienylethylamine (CAS-No.: 30433-91-1) Batch number 6U098
- Purity: 98.1%

Study design

Oxygen conditions:
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): A sample of activated sludge was collected from one of the return lines at Burley
Menston sewage treatment works (West Yorkshire, UK), which has a predominantly domestic waste-water catchment.
- Storage conditions: On arrival, the sample was aerated by means of a compressed air supply
- Concentration of sludge: nominal final solids concentration of 30 mg/L in each test vessel
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
15 mg/L
Based on:
Test material equivalent to mg organic carbon/L
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
- Composition of medium:
The test was conducted in an aqueous, synthetic, mineral salts medium. A test
medium concentrate was prepared in ultra-pure water containing 30 mL/L solution (a)
and 3 mL/L of each of solutions (b), (c) and (d). Solutions (a) to (d) were prepared as
(a) potassium dihydrogen phosphate (8.50 g, VWR, ≥ 99.0%); dipotassium hydrogen
phosphate (21.75 g, VWR, ≥ 99.0%); disodium hydrogen phosphate dihydrate
(33.40 g, Fisher, ≥ 99.0%); ammonium chloride (0.50 g, Fisher), all dissolved in and
made up to 1 L with RO water.
(b) calcium chloride dihydrate (36.40 g, VWR), dissolved in and made up to 1 L with
RO water.
(c) magnesium sulphate heptahydrate (22.50 g, Sigma Aldrich), dissolved in and
made up to 1 L with RO water.
(d) ferric chloride hexahydrate (0.25 g, Sigma Aldrich) and concentrated hydrochloric
acid (1 drop, VWR), dissolved in and made up to 1 L with RO water.

- Culturing apparatus: Test vessels containing 1.5L of test medium
- Number of culture flasks/concentration: 2 for each group - test substance, reference substance and blank control. 1 for toxicity control.
- Method used to create aerobic conditions: air used in this study was delivered from a cylinder of CO2-free air (Air Products) and was regulated in two stages. Initial control was provided by a gas regulator and the air flow to each vessel controlled by individual needle valves. Measurements of
the flow rate exiting each test vessel were made at intervals not exceeding seven days, with a bubble flow meter and stopwatch. Adjustments were made as necessary to maintain a flow rate of ca 50 mL per minute
- Measuring equipment: determined by titration of barium hydroxide stock trap bottle
- Test performed in open system: Yes
- Details of trap for CO2 and volatile organics if used: Barium hydroxide

- Sampling frequency: Days 0, 1, 4, 6, 8, 11, 15, 18, 22, 25, 28, 29
- Sampling method: At appropriate intervals, the air supply to each vessel was interrupted and the trap bottle nearest to the test vessel was removed for sampling. The remaining two bottles of the series were moved towards the test vessel, and a fresh trap bottle placed on the end of the series. Once the series of trap bottles were connected to the test vessel the air supply was restarted.

- Blank control: inoculated mineral salts medium
- Test substance: inoculated mineral salts medium and test substance
- Reference substance: inoculated mineral salts medium and sodium benzoate
- Toxicity control: inoculated mineral salts medium, test substance and sodium
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

Preliminary study:
A solubility trial was performed by weighing a sub-sample (390.9 mg calculated
quantity to ensure 225 mg carbon) of Thienylethylamine into a vessel and making up
to 100 mL with reverse osmosis (RO) water. The test substance appeared to be
soluble. The application solution was therefore added into the test vessels.
Test performance:
Not applicable
% Degradation
Key result
% degradation (CO2 evolution)
Sampling time:
28 d
Details on results:
To be considered readily biodegradable, a test substance must achieve 60%
biodegradation by the end of the test. Additionally, the test substance must biodegrade
by at least 60% within 10 days of having degraded by 10%.
Thienylethylamine showed no biodegradation during the course of the study with a
mean of 0% biodegradation. Thienylethylamine cannot, therefore, be considered
readily biodegradable.
Percent biodegradation values at each sampling interval, for the two replicates
containing Thienylethylamine did not vary, therefore satisfying the validity criterion
of less than 20% difference.

BOD5 / COD results

Results with reference substance:
Rapid carbon dioxide generation commenced immediately and declined to a more
gradual rate over the period of the incubation. The corrected
mean percentage biodegradation had exceeded 60% by Day 11 (61%), 70% by Day
28 and by the end of the study the mean biodegradation had reached a maximum of
72%. The validity criterion of 60% biodegradation at 14 days was therefore met.

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
not readily biodegradable
The reliable OECD 301B Guideline study on ready biodegradability reported a degradation rate of thienylethylamine of 0% within the 10-day window and 0% after 28 days. Therefore, thienylethylamine is considered to be not readily biodegradable.
Executive summary:

The reliable OECD 301B Guideline study on ready biodegradability reported a degradation rate of thienylethylamine of 0% within the 10-day window and 0% after 28 days. Therefore, thienylethylamine is considered to be not readily biodegradable.