[No public or meaningful name is available]

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:

09 Oct - 20 Oct 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Version / remarks:

1992

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: ISO standard 10634

Version / remarks:

1995

Principles of method if other than guideline:

Recorded deviations
• On nominal day 2 it was noticed that the ingoing aeration line was disconnected and there was a temporary breakdown in aeration for test item bottle B, the toxicity control, and blank bottle B.
Evaluation: This relatively short breakdown (<1 day) in aeration is normally considered to have no effect on the outcome of the study. Furthermore, the results for bottle B are in good agreement with bottle A for both the test item as well as the blanks while the toxicity control has satisfied the 25% biodegradation validity criterion.
• Between nominal day 17 and 18 a temporary breakdown in aeration (<1 day) occurred. This was observed in all vessels. The gas cylinders were empty.
Evaluation: Such a short breakdown in aeration does not influence the outcome or validity of the study.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Fatty acids, vegetable-oil, polymd., esters with 1,2-hexadecanediol

Cas Number:

68910-99-6

Molecular formula:

Not applicable (i.e., UVCB substance)

IUPAC Name:

Fatty acids, vegetable-oil, polymd., esters with 1,2-hexadecanediol

Test material form:

other: paste

Study design

Oxygen conditions:

aerobic

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): activated sludge obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.
- Pretreatment: The freshly obtained sludge was kept under continuous aeration until further treatment. Before use, the sludge was allowed to settle (30 min) and the supernatant liquid was used as inoculum.
- Concentration of sludge: 10 mL/L of mineral medium
- Initial cell/biomass concentration: 4.13 g/L suspended solids

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

15.5 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

12 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: The day before the start of the test (day -1) mineral components, Milli- RO water (ca. 80% of final volume) and inoculum (1% of final volume) were added to each bottle. This mixture was aerated with synthetic air overnight to purge the system of CO2.
- Test temperature: 22.2 - 23.5 °C
- pH: 7.7 - 7.6
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 2 (2 litre brown coloured glass bottles)
- Method used to create aerobic conditions: A mixture of oxygen (ca. 20%) and nitrogen (ca. 80%) was passed through a bottle containing 0.5 - 1 litre 0.0125 M Ba(OH)2 solution to trap CO2
- Details of trap for CO2 and volatile organics if used: (bottles filled with 100 mL 0.0125 M Ba(OH)2

SAMPLING
- Sampling method: Titrations were made every second or third day during the first 10 days, and thereafter at least every fifth day until day 28, for the inoculum blank and test item. Titrations for the positive and toxicity control were made over a period of at least 14 days.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates
- Positive control: 1 replicate
- Toxicity control: 1 replicate

Reference substance

Reference substance:

acetic acid, sodium salt

Results and discussion

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

28 d

Details on results:

In the toxicity control, more than 25% biodegradation occurred within 14 days (44% based on ThCO2). Therefore, the test item was assumed not to inhibit microbial activity.

Any other information on results incl. tables

Table 1: Validity criteria for OECD 301.

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	≤ 0%	yes
Percentage degradation of the reference compound has reached the pass levels by day 14.	83% after 14 d	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	44% at day 15	yes
The IC content of the test substance suspension in the mineral medium at the beginning of the test must be less than 5% of the TC.	<5%	yes
The total CO2 evolution in the inoculum blank at the end of the test should not normally exceed 40 mg/L medium.	56.2 mg CO2per 2 litres of medium	yes

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Interpretation of results:

under test conditions no biodegradation observed