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Environmental fate & pathways

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:
9 May 2019 - 25 July 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report date:
2019

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
2006
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Version / remarks:
Regulation (EC) No 440/2008
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Reference substance 001
Cas Number:
67-47-0
Molecular formula:
C6H6O3
impurity 1
Chemical structure
Reference substance name:
Fructose
EC Number:
200-333-3
EC Name:
Fructose
Cas Number:
57-48-7
Molecular formula:
C6H12O6
IUPAC Name:
D-fructose
impurity 2
Chemical structure
Reference substance name:
1-(furan-2-yl)-2-hydroxyethanone
Cas Number:
17678-19-2
Molecular formula:
C6H6O3
IUPAC Name:
1-(furan-2-yl)-2-hydroxyethanone
impurity 3
Reference substance name:
Water
EC Number:
231-791-2
EC Name:
Water
Cas Number:
7732-18-5
Molecular formula:
H2O
IUPAC Name:
water
impurity 4
Chemical structure
Reference substance name:
Sodium formate
EC Number:
205-488-0
EC Name:
Sodium formate
Cas Number:
141-53-7
Molecular formula:
CH2O2.Na
IUPAC Name:
sodium formate
impurity 5
Chemical structure
Reference substance name:
Sodium nitrate
EC Number:
231-554-3
EC Name:
Sodium nitrate
Cas Number:
7631-99-4
Molecular formula:
HNO3.Na
IUPAC Name:
sodium nitrate
impurity 6
Chemical structure
Reference substance name:
Glucose
EC Number:
200-075-1
EC Name:
Glucose
Cas Number:
50-99-7
Molecular formula:
C6H12O6
IUPAC Name:
D-glucose
impurity 7
Chemical structure
Reference substance name:
Sodium acetate
EC Number:
204-823-8
EC Name:
Sodium acetate
Cas Number:
127-09-3
Molecular formula:
C2H4O2.Na
IUPAC Name:
sodium acetate
impurity 8
Chemical structure
Reference substance name:
2-furaldehyde
EC Number:
202-627-7
EC Name:
2-furaldehyde
Cas Number:
98-01-1
Molecular formula:
C5H4O2
IUPAC Name:
2-furaldehyde
impurity 9
Chemical structure
Reference substance name:
Sodium 4-oxovalerate
EC Number:
243-378-4
EC Name:
Sodium 4-oxovalerate
Cas Number:
19856-23-6
Molecular formula:
C5H8O3.Na
IUPAC Name:
sodium 4-oxopentanoate
impurity 10
Chemical structure
Reference substance name:
Formaldehyde
EC Number:
200-001-8
EC Name:
Formaldehyde
Cas Number:
50-00-0
Molecular formula:
CH2O
IUPAC Name:
formaldehyde
Test material form:
solid: crystalline
Details on test material:
freeze-dried material
Batch: 1808A-RO-C-I1-FD-Chg#3
Appearance Crystal / brown
Storage: Refrigerator (2 - 8 °C)
Expiring date: 31 December 2019

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source: Sludge from the aeration tank of the ARA Werdhölzli (CH-8048 Zürich), a municipal biological waste water treatment plant.
- Preparation of inoculum for exposure: The sludge was pre-conditioned for 7 days (aerated but not fed) to reduce the amount of O2 consumed by the blank controls. Therefore, the sludge was washed twice with tap water and once with test medium.
- Pretreatment: The activated sludge was used after sampling from the treatment plant without adaptation.
- Concentration of sludge: 30 mg/L dry matter in the final mixture.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
71.5 mg/L
Based on:
other: nominal test item concentration based on 101 mg ThOD/L
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of test medium: A mineral salt medium was prepared according to the test guideline and used for sludge preconditioning and testing (except for the abiotic sterile control. Analytical grade salts were dissolved in ultra-pure water to obtain the concentrations. The pH value of the test medium was adjusted to 7.4±0.2.

- Test temperature: 22±2°C, controlled at ±1°C, in a thermostat cabinet in the dark
- pH: 6.0-8.5
- Continuous darkness: yes, test bottles were in a thermostat cabinet.

TEST SYSTEM
- Test flasks: 510 mL glass bottles (tightly closed with manometric BOD measuring devices) contain ing a total volume of test solution of 200 mL. The bottles were equipped with stirring rods and butyl rubber quivers which contain 2 pellets of sodium hydroxide each to absorb the produced CO2 from the head space.
- Test performed in duplicate (two test flasks)

After centrifugation, the sludge was suspended in test medium at about 2 g/l dry matter and kept under constant aeration and stirring without feeding for 7 days, until test start. On the day of the test start, this sludge suspension was diluted down to 60 mg/l dry matter, i.e. twice as high as the final test concentration, as this suspension was diluted by a factor of two afterwards to obtain a final dry matter concentration of 30 mg/l in the test vessels.

CONTROL AND BLANK SYSTEM
B: Inoculum blank (two replicates)
R: Procedure control (two replicates): 60.1 mg/L Sodium benzoate (100 mg ThOD/L)
A: Abiotic sterile control (one replicate): 71.5 mg/L test item (101 mg ThOD/L)
X: Toxicity control (one replicate): 71.5 mg/L test item and 60.1 mg/L Sodium benzoate (total 201 mg oxygen demand/L)

SAMPLING
The test vessels were stirred by an inductive stirring system for a maximum test period of 28 days. During the test the O2 uptake was continuously measured with a manometric BOD measuring device. Temperature was recorded with a data logger.
At the end of the test, the pH was measured in all flasks except the abiotic sterile control (A).
Total elimination was determined in each test vessel (test suspension, blank and procedure control) based on the theoretical carbon content and the analysis of the dissolved organic carbon (DOC) concentrations at the end of the test.

STATISTICAL METHODS:
Values of % degradation were calculated for each test flask and day. The arithmetic mean of % degradation in each test flask on each day was calculated.
Reference substance
Reference substance:
other: Sodium benzoate
Remarks:
CAS 532-32-1

Results and discussion

% Degradation
Key result
Parameter:
% degradation (O2 consumption)
Value:
76
Sampling time:
28 d
Remarks on result:
other: test flask 1 after 28 d: 77.5% test flask 2 after 28 d: 75.5%
Details on results:
The biodegradability of 5-(Hydroxymethyl)furfural based on O2 consumption was calculated to be 76% after 28 days as compared to the theoretical oxygen demand (ThOD).
The biodegradation reached 68% at the end of the 10-d window.
Biodegradation of the test item started without any significant lag-phase.
The procedure control with sodium benzoate reached a biodegradation of 85% after 14 days, thus confirming suitability of inoculum and test conditions.

The respective concentrations of organic carbon at the beginning (theoretical value based on the test item’s carbon content and the test concentration, as mg TOC/L) and at the end of the test (mean measured value of the two replicates, as mg DOC/L) were, respectively:
- test units: 36.3 (theoretical value calculated based on the carbon content and the test concentration) and 2.41 (mean of two replicates)
- blank control: <0.5 and 0.91 (mean of two replicates)
- procedure control: 34.2 (theoretical value calculated based on the carbon content and the test concentration) and 0.99 (mean of two replicates)

The total elimination calculated based on dissolved organic carbon (DOC) measurements reached 96% for 5-(Hydroxymethyl)furfural and 100% for sodium benzoate, respectively. These data confirm the high biodegradability of the test item.

BOD5 / COD results

Results with reference substance:
Results with reference substance

Any other information on results incl. tables

Procedure control:

The procedure control sodium benzoate reached 85% biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.

Toxicity control:

At the applied initial test concentration of 71.5 mg/L the test item was not judged to have any inhibitory effect on the microbial population, since the biodegradation of the mixture (test item + reference item sodium benzoate) exceeded 25% within 14 days.

Abiotic steril control:

5-(Hydroxymethyl)furfural was not abiotically degraded (by processes using O2) during the whole test period of 28 days in the absence of microorganisms as confirmed by the lack of significant oxygen consumption.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
A 28-d ready biodegradability test (OECD 301F, Manometric Respirometry Test) using activated sludge of a municipal sewage treatment plant indicated that 5-(Hydroxymethyl)furfural (CAS no. 67-47-0) reached the pass level of 60% for ready biodegradability in the Manometric Respirometry Test within the 10-d window and, therefore, can be termed as readily biodegradable.
Executive summary:

The biodegradability of 5-(Hydroxymethyl)furfural (CAS no. 67-47-0) exposed to microorganisms derived from activated sludge of a municipal sewage treatment plant was investigated under aerobic static exposure conditions, following the OECD guideline 301 F. Both the biodegradation over the course of the test (based on O2 consumption compared to the theoretical oxygen demand ThOD) and the total elimination at the end of the test (based on the determination of the dissolved organic carbon, DOC) were assessed.

Based on O2 consumption the biodegradation of 5-(Hydroxymethyl)furfural was calculated to be 76% of the ThOD after 28 days and reached 68% at the end of the 10-d window (i.e. within 10 days after attainment of 10% degradation).

Biodegradation of the test item started without any significant lag-phase.

The procedure control with sodium benzoate reached a biodegradation of 85% after 14 days, thus confirming suitability of inoculum and test conditions.

Based on the determination of the DOC at the end of the test the total elimination was calculated to be 96% for 5-(Hydroxymethyl)furfural and 100% for sodium benzoate. This data is in line with the

degradation calculated based on O2 consumption.

5-(Hydroxymethyl)furfural (CAS no. 67-47-0) reached the pass level of 60% biodegradation in the Manometric Respirometry Test within the 10-day window and, therefore, can be termed as readily biodegradable.

All validity criteria were fulfilled.