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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:
January - March 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
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
yes
Remarks:
This deviation has no incidence on study results.
GLP compliance:
yes

Test material

Constituent 1
Reference substance name:
Almond, sweet, ext.
EC Number:
291-063-5
EC Name:
Almond, sweet, ext.
Cas Number:
90320-37-9
IUPAC Name:
Proteins from sweet almond extract
Test material form:
solid: particulate/powder
Details on test material:
- Appearance: white powder
- Storage: in a dark place at room temperature
- Batch : 16 187
- Manufacturing date: July 5th 2016
- Expiry date: July 5th 2018

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: The inoculum was a fresh sample of activated sludge and was collected from the aeration tank of a sewage treatment plant receiving predominantly domestic sewage.
- Sample site: Water treatment plant "STEP de Lille", 33290 Blanquefort (France) - Tank 2.
- Laboratory culture: A filtration through a fine sieve (about 1 mm) was performed in order to remove coarse particles. After removal of any coarse particles, the sludge was washed by recantation in a mineral medium until sludge was considered free from excess substrate or inhibitor.
- Inoculum preconditioning: Pre-conditioning consisted in aerating sludge (in mineral medium) for 5-7 days before the test and at the test temperature.
Duration of test (contact time):
ca. 28 d
Initial test substance concentration
Initial conc.:
ca. 100 g/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST ITEM PREPARATION
The test item is soluble in water; it was diluted with mineral medium at 1g/L and directly introduced with sludge into each test vessels.
The test item “POLYLIFT AT” was tested at 100 mg/L in mineral medium.
The test medium was the mineral medium, a weakly saline aqueous medium.

TEST CONDITIONS
Composition of medium: Mineral medium according to OECD 301F guideline
- Test temperature: The test was performed in darkness between 21.9 to 22.4°C (constant temperature +/- 1°C).
- Mineral medium - pH: 7.6
- Inoculum : pH: 6.4, Dissolved oxygen: 8.6 mg/L, Suspended solids concentration: 2.76 g/L
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: WTW Oxitop (FCBA reference: ACQU 1011)
- Number of culture flasks/concentration: 3 flasks (test item and inoculum)
- Test performed in closed vessels: Yes
- A measured volume of inoculated medium containing a known concentration of the test item (100 mg/L) as the nominal sole source of Carbon, was stirred in a closed vessel at a constant temperature up to 28 days.
- Details of trap for CO2: Microbial respiration consumes O2 and releases CO2 which were absorbed by soda lime pellets present in the headspace of flasks. This produced a decrease in pressure in the flask proportional to the amount of oxygen taken up by the microbial population during biodegradation
, which was expressed as a percentage of ThOD (Theoretical Oxygen Demand).
- Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without the test item. Furthermore, in order to check the procedure, a reference item control (sodium benzoate 60.2 mg/L + inoculum) and toxicity control (sodium benzoate + inoculum + test item) were run in parallel.

SAMPLING
- Sampling frequency: 0 to 28 days

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes; 3 flasks (inoculum only)
- Reference item: 2 flasks (Sodium benzoate and inoculum)
- Toxicity control: Yes; 2 flasks (test item, sodium benzoate and inoculum)
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

Preliminary study:
none
% Degradationopen allclose all
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
following the ThOD-NH4
Value:
ca. 82.69
St. dev.:
5.29
Sampling time:
28 d
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
following the ThOD-N03
Value:
ca. 53.93
St. dev.:
3.45
Sampling time:
28 d
Details on results:
The test item “POLYLIFT AT” contains proteins, so nitrogen has been dosed in the elementary analyses, the evaluation of biodegradation had to be based in the following expressed as ThODNH4 and ThODNO3.

The degradation for the 10-day window beginning was reached on Day 2, at the end of the 10-day window (reaching at least 60%), on Day 5, the mean degradation was 66.14% following the ThODNH4 and therefore the D-day window was reached.
The degradation rate of the test item “POLYLIFT AT” reached 82.69% (between 76.58% and 85.75%), following the ThODNH4, after 28 days of incubation.

The degradation for the 10-day window beginning was reached on Day 2, at the end of the 10-day window, on Day 12, the mean degradation was 52.92% following the ThODNO3 and therefore the D-day window was failed
The degradation rate of the test item “POLYLIFT AT” reached 53.93% (between 49.95% and 55.92%), following the ThODNO3, after 28 days of incubation.

According to the OECD guideline 301F, the test item is readily biodegradable according to ThODNH4.
According to the OECD guideline 301F, the test item is not considered to be readily biodegradable according to ThODNO3.

Toxicity control:
A biodegradation of 84.99% (with ThODNH4) and 65.85% (with ThODNO3) after 14 days of incubation was noted in the Toxicity control (containing both of the test item and the reference item).
At the end on the test, 28 days of incubation, the results were respectively 87.59% and 67.87%.
Therefore, the test item was not inhibitory at the tested concentration on the aerobic activated sludge micro-organism because degradation was >25% within 14 days (validity criterion).

BOD5 / COD results

Results with reference substance:
The reference item “Sodium benzoate” was degraded up to 88.69% after 28 days.
Therefore, it confirms the suitability of the used aerobic sludge inoculum.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Remarks:
Based on ThODNH4
Conclusions:
Based on ThODNH4, the 10-Day window was reached on Day 5 and the results obtained show that the test item can be considered readily biodegradable after 28 days of incubation with a mean percentage of biodegradation rate of 82.69%.
Based on ThODNO3, the 10-Day window failed.The results obtained show that the test item cannot be considered readily biodegradable after 28 days of incubation with a mean percentage of biodegradation rate of 53.93%.
Under conditions of OECD Guideline 301F, the test item “POLYLIFT AT”, cannot be considered readily biodegradable based on ThODNO3, assuming nitrification occurs.
Executive summary:

The ready biodegradability of the test item has been determined by the Manometric Respirometry Test according to the OECD Guideline No. 301F with GLP compliance.

A measured volume of inoculated medium containing a known concentration of the test item (100 mg/L) as the nominal sole source of Carbon, was stirred in a closed vessel at a constant temperature up to 28 days. Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without the test item. Furthermore, in order to check the procedure, a reference item control (sodium benzoate 60.2 mg/L+ inoculum) and toxicity control (sodium benzoate + inoculum +test item) were run in parallel. The amount of oxygen taken up by the microbial population during the biodegradation of the test item (corrected by blank inoculum, run in parallel) was determined from the change in pressure in apparatus and will be expressed as percentage of theoretical Oxygen Demand (ThOD).

The test item “POLYLIFT AT” contains nitrogen the elementary analyses, the evaluation of biodegradation had to be based in the following expressed as ThODNH4and ThODNO3.

The degradation for the 10-day window beginning was reached on Day 2, at the end of the 10-day window (reaching at least 60%), on Day 5, the mean degradation was 66.14% following the ThODNH4and therefore the D-day window was reached.

The degradation rate of the test item “POLYLIFT AT” reached 82.69% (between 76.58% and 85.75%), following the ThODNH4, after 28 days of incubation.

The degradation for the 10-day window beginning was reached on Day 2, at the end of the 10-day window, on Day 12, the mean degradation was 52.92% following the ThODNO3and therefore the D-day window was failed.

The degradation rate of the test item “POLYLIFT AT” reached 53.93% (between 49.95% and 55.92%), following the ThODNO3, after 28 days of incubation.

  According to the OECD guideline 301F, the test item is readily biodegradable according to ThODNH4.

 According to the OECD guideline 301F, the test item is not considered to be readily biodegradable according to ThODNO3.