[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:

30 July - 27 Aug 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2,2-bis[(hexadecanoyloxy)methyl]propane-1,3-diyl dihexadecanoate

Cas Number:

18641-58-2

Molecular formula:

C69H132O8

IUPAC Name:

2,2-bis[(hexadecanoyloxy)methyl]propane-1,3-diyl dihexadecanoate

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge was collected on 29 July 2020 from an aeration tank of a sewage treatment plant treating predominantly domestic sludge in Kurume-shi, Fukuoka, Japan
- Storage conditions: aerated at approximately 22°C until use for the test
- Concentration of sludge: concentration of suspended solids in the collected activated sludge was 2040 mg/L (determined on 29 July 2020)

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

30.5 mg/L

Based on:

other: test item

Initial test substance concentration 2

Initial conc.:

88 mg/L

Based on:

ThOD

Remarks:

test item

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: According to the guideline
- Additional substrate: No
- Test temperature: 22±1°C
- pH: 7.3-7.4, measured on day 28 in the test suspension and inoculum blank
- pH adjusted: Yes
- Suspended solids concentration: 30 mg/L
- Continuous darkness: Yes
- Other: In each test vessel, 0.5 g of silica gel was added and stirred for 30 minutes with a stirrer at room temperature. Each test solution was stirred with a stirrer during the incubation period

TEST SYSTEM
- Culturing apparatus: Glass vessels
- Number of culture flasks/concentration: 2 (each containing 9.16 mg test item + 0.5 g silica gel + 4.41 mL inoculum + test media for a total test solution volume of 300 mL)
- Measuring equipment: Closed system oxygen consumption measuring apparatus
- Details of trap for CO2: Soda lime

SAMPLING
- Sampling frequency: BOD of the test solutions was measured continuously during the incubation period with a closed system oxygen consumption measuring apparatus
- Other: appearances of test suspensions and inoculum blank were observed and recorded

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates (each containing 0.5 g silica gel + 4.41 mL inoculum + test media for a total test solution volume of 300 mL)
- Procedure control: 1 replicate (0.5 g silica gel + 30 mg reference substance + 4.41 mL inoculum + test media for a total test solution volume of 300 mL)
- Toxicity control: 1 replicate (9.16 mg test item + 0.5 g silica gel + 30 mg reference substance + 4.41 mL inoculum + test media for a total test solution volume of 300 mL)

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

60

Sampling time:

28 d

Details on results:

- The % biodegradation was calculated on the basis of the ThOD of the test item (Pentaerythritol tetrapalmitate, constituting 91.6% of the test material). The test sample was corrected with the purity of the test item. It is noted that the percentage degradation may include biodegradation of the impurity.
- The 28-d biodegradation of the test item was 60% (average). The pass level of biodegradation was not reached within the 10-d window. The 10-d window for the test item started on day 3 (02 Aug 2020) and after 10 days (12 Aug 2020) the biodegradation of the test item was 47% (average).
- 66% biodegradation occurred within 14 days in the toxicity control and therefore the test item was not toxic to microorganisms.

BOD5 / COD results

Results with reference substance:

> 60 % biodegradation of the reference substance occurred within 14 days (90% in 14 d)

Any other information on results incl. tables

BIOLOGICAL RESULTS:
Table 1: % biodegradation of test item, procedure control and toxicity control

Time (days)	Test item solution 1	Test item solution 2	Procedure control	Toxicity control
7	30	31	83	55
14	49	48	90	66
21	58	54	94	76
28	62	57	96	82

VALIDITY CRITERIA:
Table 2: Validity criteria for OECD TG 301

Validity 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%.	Difference of extremes 5%	Yes
Percentage degradation of the reference compound reached the pass level by day 14 (≥ 60%).	90% in 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.	66% in 14 d	Yes
The oxygen uptake of the inoculum blank is normally 20-30 mg O2/L and should not be greater than 60 mg/L in 28 days.	19-21 mgO2/L in 28 d	Yes

OTHER OBSERVATIONS:
Table 3: Appearances of test suspension and incolum blank

Test solution	Appearance at the start of incubation	Appearance at the end of incubation
Test item solution	Test item was not dissolved	The presence or absence of insoluble compound except the sludge could not be confirmed. Growth of sludge was observed
Inoculum blank	Insoluble compound except the sludge was not observed	Insoluble compound except the sludge was not observed

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:

inherently biodegradable

Executive summary:

The biodegradability of Pentaerythritol tetrapalmitate was tested in a GLP study according to OECD TG 301F, where the test material was incubated for 28 days with an inoculum collected from a municipal sewage treatment plant treating predominantly domestic sludge. Silica gel was added to improve the bioavailability of the poorly water soluble test item. The concentration of inoculum in the test vessels was 30 mg suspended solids/L and the concentration of the test item (Pentaerythritol tetrapalmitate) was 30.5 mg/L (88 mg ThOD/L). The degradation of test item was monitored by assessing O2 consumption and the results were calculated by subtracting the amount of BOD in the inoculum blank from the amount of BOD from the test item sample and dividing by the ThOD of the test item (Pentaerythritol tetrapalmitate). A procedure and a toxicity control were run in parallel.

All validity criteria of the TG were fulfilled. In the toxicity control, 66% biodegradation occurred in 14 d and therefore the test item is not toxic to microorganisms.

The 28-d biodegradation of the test item was 60%. This level of biodegradation was not reached within the 10-d window. Therefore, in accordance with Section R.7.9.4.1 of the Guidance on Information Requirements and Chemical Safety Assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2017), the test item is considered as inherently biodegradable.