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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:
03.2018 to 04.2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
(1992)
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Version / remarks:
(2008)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): A fresh sample of activated sludge from a municipal sewage treatment plant (Schmallenberg, Germany) was collected.
- Laboratory culture: no
- Preparation of inoculum for exposure: Since it was not necessary, the samples were not washed with mineral medium after the arrival at the laboratory but kept aerobic until use. The sludge was left for settlement for ca. one hour. Subsequently the supernatant was discarded and the concentration of suspended solids was measured in the remaining sludge. The concentration was adjusted to 4.0 g/L and verified by dry mass measurement. The concentration used in the test was 29.7 mg dry mass/liter (7.4 mg dry mass/250 mL).
- Pretreatment: no
- Concentration of sludge: 29.7 mg dry mass/liter
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
100 mg/L
Based on:
test mat.
Initial conc.:
32 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: For the preparation of the stock solutions for mineral medium the following reagents (analytical grade) were used:
( a ) KH2PO4 8.51 g/L
K2HPO4 21.74 g/L
Na2HPO4 x 2 H2O 33.42 g/L
NH4Cl 0.50 g/L
pH 7.4 ± 0.2

( b ) CaCl2 x 2 H2O 36.41 g/L
( c ) MgSO4 x 7 H2O 22.51 g/L
( d ) FeCl3 x 6 H2O 0.25 g/L.
The mineral medium applied in the test contained 10 mL/L of mineral stock solution a and 1 mL/L of the mineral stock solution b–d, respectively.

- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Test temperature: 22 +/- 1°C
- pH: Before test start the pH values of all solutions were determined and adjusted to 7.4 ± 0.2 with H2SO4 (50 g/L) (Table 1). At the end of the test the pH values of all solutions were determined again.
- pH adjusted: yes
- Aeration of dilution water: not reported
- Suspended solids concentration: 39.7 mg dry mass / L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: respirometer
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: activated sludge
- Measuring equipment: respirometer (Sapromat, Voith Inc.)
- Test performed in closed vessels: yes
- Details of trap for CO2 and volatile organics if used: suitable absorbent used


SAMPLING
- Sampling frequency: 1/day
- Sampling method: oxygen uptake was measured
- Sample storage before analysis: no

CONTROL AND BLANK SYSTEM
- Inoculum blank: performed
- Abiotic sterile control: performed
- Toxicity control: performed
- Other: procedural control with reference substance performed
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (O2 consumption)
Value:
1
St. dev.:
1.1
Sampling time:
28 d
Remarks on result:
other: With degradation rates below 10 % over the complete test duration in the 100 mg/L assays, no degradation rate within a 10-day-window can be calculated.

BOD5 / COD results

Results with reference substance:
The reference substance sodium benzoate was biodegraded by 90% within 14 d thus fulfilling the guideline criterion.

Any other information on results incl. tables

The biodegradation of Neodecanoic acid, tin (2+) salt (2:1) in the static test was found to be at mean 1% with a standard deviation of 1.1% for a concentration of 100 mg test item per liter and at mean 12% with a standard deviation of 9.2% for a concentration of 32 mg test item per liter after 28 days. However, with 14 % (SD = 9.2 %), the maximum mean degradation rate within the 28 day test duration was found in the 32 mg/L assays. For a concentration of 32 mg test item per liter, biodegradation within the 10-day-window was found to be 13%. The 10-day-window started at mean at day 15. With degradation rates below 10 % over the complete test duration in the 100 mg/L assays, no degradation rate within a 10-day-window can be calculated.

The degradation of the reference substance sodium benzoate had reached 90% within the first 14 days. The difference of extremes of replicate values of the removal of the test item at the end of the test for 100 mg/L and 32 mg/L, respectively, is less than 20%. Therefore, the test can be considered as valid. No inhibitory effects of the test item were observed (more than 25% degradation occurred within 14 days) in the toxicity control.

Conclusion:

According to the guideline, Neodecanoic acid, tin (2+) salt (2:1) must be considered as being not readily biodegradable under the test conditions applied.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
According to the guideline, PU-2017-793 must be considered as being not readily biodegradable under the test conditions applied.
Executive summary:

The ready biodegradation of Neodecanoic acid, tin (2+) salt (2:1) was investigated in a study conducted according to OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test) and EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test) over a period of 28 days and using non-adapted activated sludge as inoculum. The biodegradation rate was determined by measurement of oxygen consumption. Inoculum blank, procedural/functional control with the reference substance sodium benzoate, and toxicity control using 100 mg/L test item and 100 mg/L reference compound were performed.

The biodegradation of Neodecanoic acid, tin (2+) salt (2:1) in the static test was found to be at mean 1% with a standard deviation of 1.1% for a concentration of 100 mg test item per liter and at mean 12% with a standard deviation of 9.2% for a concentration of 32 mg test item per liter after 28 days. However, with 14 % (SD = 9.2 %), the maximum mean degradation rate within the 28 day test duration was found in the 32 mg/L assays. For a concentration of 32 mg test item per liter, biodegradation within the 10-day-window was found to be 13%. The 10-day-window started at mean at day 15. With degradation rates below 10 % over the complete test duration in the 100 mg/L assays, no degradation rate within a 10-day-window can be calculated.

The degradation of the reference substance sodium benzoate had reached 90% within the first 14 days. The difference of extremes of replicate values of the removal of the test item at the end of the test for 100 mg/L and 32 mg/L, respectively, is less than 20%. Therefore, the test can be considered as valid. No inhibitory effects of the test item were observed (more than 25% degradation occurred within 14 days) in the toxicity control.

Conclusion:

According to the guideline, Neodecanoic acid, tin (2+) salt (2:1) must be considered as being not readily biodegradable under the test conditions applied.