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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:
27 April - 26 May 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 guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
2006
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Version / remarks:
Regulation (EC) No 440/2008
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
impurity
Test material form:
solid: crystalline
Remarks:
crystalline powder
Details on test material:
Batch No: 11679700
Storage: at room temperature, protected from light

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.:
62.5 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: 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 in the dark
- pH: 7.4±0.2°C (measured prior to testing and if necessary adjusted with NaOH or HCl (except in flask C, T and X).
- 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 2 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. The test item was applied by direct addition into the test vessels to give a final test concentration as ThOD of about 100 mg O2/l.

CONTROL AND BLANK SYSTEM
B: Inoculum blank (two replicates)
R: Procedure control (two replicates): 60.3 mg/L Sodium benzoate (100 mg ThOD/L)
C: Abiotic sterile control (one replicate): 63.5 mg/L test item (102 mg ThOD/L)
X: Toxicity control (one replicate): 64.0 mg/L test item and 60.3 mg/L reference item (total 204 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:
88
Sampling time:
28 d
Remarks on result:
other: test flask 1 after 28 d: 86.6% test flask 2 after 28 d: 88.6%
Details on results:
The biodegradability of Adenosine-5’-monophosphate (AMP) based on O2 consumption was calculated to be 88% after 28 days as compared to the theoretical oxygen demand (ThOD). The biodegradation reached 85% at the end of the 10-d window. Biodegradation of the test item was observed after a lag-phase of about 1 day.

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: 21.6 (theoretical value calculated based on the carbon content and the test concentration) and 0.974 (mean of two replicates)
- blank control: <0.5 and 0.739 (mean of two replicates)
- procedure control: 35.1 (theoretical value calculated based on the carbon content and the test concentration) and 0.951 (mean of two replicates)

The total elimination calculated based on dissolved organic carbon (DOC) measurements reached 99% for Adenosine-5’-monophosphate (AMP) and 99% 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 88% biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.

Toxicity control:

At the applied initial test concentration of 64.5 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:

Adenosine-5’-monophosphate (AMP) 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
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 Adenosine-5’-monophosphate (AMP) (CAS no. 61-19-8) exposed 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 Adenosine-5’-monophosphate (AMP) (CAS no. 61-19-8) 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 Adenosine-5’-monophosphate (AMP) based on O2 consumption was calculated to be 88% after 28 days as compared to the theoretical oxygen demand (ThOD).

The biodegradation reached 85% at the end of the 10-d window (i.e. within 10 days after attainment of 10% degradation).

Biodegradation of the test item was observed after a lag-phase of about 1 day.

The procedure control sodium benzoate reached 88% biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.

The total elimination calculated based on dissolved organic carbon (DOC) measurements reached 99% for Adenosine-5’-monophosphate (AMP) and also for sodium benzoate. This data is in line with the degradation calculated based on O2 consumption.

Adenosine-5’-monophosphate (AMP) (CAS no. 61-19-8) 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.

All validity criteria were fulfilled.