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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:
23 November - 23 December 2016
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 guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
2006
Deviations:
yes
Remarks:
The pH value of one blank control was 8.7 at the end of the test (required range: 6.0-8.5). However, the deviation is minor, the other validity criteria were fulfilled and the two blank replicates showed a very similar oxygen consumption.
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Version / remarks:
Regulation (EC) No 440/200
Deviations:
yes
Remarks:
The pH value of one blank control was 8.7 at the end of the test (required range: 6.0-8.5). However, the deviation is minor, the other validity criteria were fulfilled and the two blank replicates showed a very similar oxygen consumption.
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Adenosine 5'-(tetrahydrogen triphosphate), disodium salt
EC Number:
213-579-1
EC Name:
Adenosine 5'-(tetrahydrogen triphosphate), disodium salt
Cas Number:
987-65-5
Molecular formula:
C10H14N5O13P3.2Na
IUPAC Name:
disodium 9-{5-O-[hydroxy({[(hydroxyphosphinato)oxy]phosphinato}oxy)phosphoryl]pentofuranosyl}-9H-purin-6-amine
impurity 1
Chemical structure
Reference substance name:
Water
EC Number:
231-791-2
EC Name:
Water
Cas Number:
7732-18-5
Molecular formula:
H2O
IUPAC Name:
Oxidane
impurity 2
Reference substance name:
Unknown impurities.
Molecular formula:
Not available as unknown impurities.
IUPAC Name:
Unknown impurities.
Test material form:
solid: crystalline
Details on test material:
Storage conditions: 2-8°C
Batch No: 11678500

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 6 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.:
98.4 mg/L
Based on:
other: nominal test item concentration based on 100 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: Aerobic mineral salts medium prepared with ultrapure water (conductivity: <1.5 µS/cm; DOC: <0.5 mg/L)
* mineral stock solution A (10mL/L): 8.5 g/L KH2PO4, 28.49 g/L K2HPO4.3H2O, 33.4 g/L Na2HPO4.2H2O, 0.5 g/L NH4Cl, pH 7.4
* mineral stock solution B (1 mL/L): 36.4 g/L CaCl2.2H2O
* mineral stock solution C (1 mL/L): 22.5 g/L MgSO4.7H2O
* mineral stock solution D (1 mL/L): 0.25 g/L FeCl3.6H2O
* Final test medium: 10 mL of solution A and 1 mL of solutions B, C and D per L of test medium

- Test temperature: 22±2°C, controlled at ± 1°C, in a thermostat cabinet
- pH: 7.4±0.2°C (measured prior to testing and if necessary adjusted with NaOH or HCl (except in flask C).
- 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) containing 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 3 g/L dry matter. Before the test, this suspension was diluted down to 60 mg/L dry matter, i.e. twice the final concentration, since this suspension was diluted 1:1 (v:v) afterwards. Since the test item is well soluble, it was dissolved in the test medium at a concentration twice of the final concentration to be achieved for the test. This stock solution was diluted in the sludge suspension 1:1 (v:v) to give a final test concentration of about 100 mg ThOD/l.

CONTROL AND BLANK SYSTEM
B: Inoculum blank (two replicates)
R: Procedure control (two replicates): 60.2 mg/L Sodium benzoate (100 mg ThOD/L)
C: Abiotic sterile control (one replicate): 99.0 mg/L test item (101 mg ThOD/L)
X: Toxicity control (one replicate): 97 mg/L test item and 60.2 mg/L reference item (total 199 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 (C).
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:
83
Sampling time:
28 d
Remarks on result:
other: test flask 1 after 28 d: 83.4% test flask 2 after 28 d: 83.4%
Details on results:
The biodegradability of ATP, Di-Na based on O2 consumption was calculated to be 83% after 28 days as compared to the theoretical oxygen demand (ThOD).
The biodegradation reached 83% at the end of the 10-d window. Biodegradation of the test item was observed without any lag-phase.

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: 21.5 (theoretical value calculated based on the carbon content and the test concentration) and 1.50 (mean of two replicates)
- blank control: <0.5 and 1.04 (mean of two replicates)
- procedure control: 35.1 (theoretical value calculated based on the carbon content and the test concentration) and 1.04 (mean of two replicates)

The total elimination calculated based on dissolved organic carbon (DOC) measurements reached 98% for ATP, Di-Na and 100% for sodium benzoate, respectively. These data confirm the high biodegradability of the test item.

Any other information on results incl. tables

Procedure control:

The procedure control sodium benzoate reached 90% biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.

Toxicity control:

At the applied initial test concentration of 99.0 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:

ATP, Di-Na 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 oxygen consumption.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
The pH value of one blank control was 8.7 at the end of the test (required range: 6.0-8.5). However, the deviation is minor, the other validity criteria were fulfilled and the two blank replicates showed a very similar oxygen consumption.
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 ATP, Di-Na (CAS 987-65-5) reached a biodegradation of 83% based on O2 consumption. The substance 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 ATP, Di-Na (CAS 987-65-5) exposed to microorganisms derived from activated sludge of a municipal sewage treatment plant was investigated under aerobic static exposure conditions, following the test guideline OECD 301 F.

The biodegradability of ATP, Di-Na based on O2 consumption was calculated to be 83% after 28 days as compared to the theoretical oxygen demand (ThOD).

The biodegradation reached 83% at the end of the 10-d window. Biodegradation of the test item occurred without any lag-phase.

The procedure control sodium benzoate reached 90% biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.

The total elimination calculated based on dissolved organic carbon (DOC) measurements reached 98% for ATP, Di-Na and 100% for sodium benzoate, respectively. These data confirm the high biodegradability of the test item.

ATP, Di-Na 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.