[No public or meaningful name is available]

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:

05 NOV 2020 - 27 JAN 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2021

Report date:

2021

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: “Testing Guidelines for Studies of Chemicals, Chapter 4 Degradation and Accumulation test field, Section 3 Biodegradation Study (Ready Biodegradability): Modified MITI(I)”

Version / remarks:

National Institute of Environmental Research Notification No. 2020-28 (Aug. 19, 2020)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Version / remarks:

adopted on 17th July 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

bis(2,2,6,6-tetramethyl-1-(1,3-benzothiazol-2-ylsulfanyl)piperidin-4-yl)carbonate

Cas Number:

2311845-49-3

Molecular formula:

C33H42N4O3S4

IUPAC Name:

bis(2,2,6,6-tetramethyl-1-(1,3-benzothiazol-2-ylsulfanyl)piperidin-4-yl)carbonate

Test material form:

solid: particulate/powder

Study design

Oxygen conditions:

anaerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Remarks:

Fresh samples collected from different sites in Korea were incubated for over one month and the activated sludge greater than 10^7 cells/mL was used in this test.

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Inoculum used in this study was collected from 11 sites in Korea including 5 rivers (Gangjeong, Mulgeum, Gwangju, Daejeon, Paldang), 4 domestic sewage treatment plants (Dalseo, Gumi, Busan, Jungrang) and 2 industrial wastewater treatment plants (Dalseo, Yeosu). Annual collection at 4 times (Mar, Jun, Sep and Dec)
- Storage conditions: Fresh samples collected from these sites were incubated for over one month, condition of the inoculum: dissolved oxygen 8.14 mg/L, pH 7.23 and temperature 25.1 °C
- Preparation of inoculum for exposure: Six bottles were prepared for exposure, mixing the activiated sludge with dionizied water, basal culture medium, nitrification inhibitor for treatment with the test item or control substance or control bottles as appropriate.
- Pretreatment: not specified
- Concentration of sludge: inoculum was treated at a concentration of about 10^7-10^8 cells/L

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

100 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: Composition of stock solutions for basal culture medium were prepared as follows. Dissolve A, B, C and D solutions in deionized water at the ratio of 0.3 %.
Solution A : Dipotassium hydrogen orthophosphate 2.175 g, Potassium dihydrogen rthophosphate 0.850 g, Disodium hydrogen orthophosphate dodecahydrate 4.460 g, Ammonium chloride 0.170 g
Dissolve in deionized water and make up to 100 mL. The pH value of the solution is adjusted to 7.2.
Solution B : Magnesium sulfate heptahydrate 2.250 g, Dissolve in deionized water and make up to 100 mL.
Solution C : Calcium chloride anhydrous 2.750 g, Dissolve in deionized water and make up to 100 mL.
Solution D : Iron(III) chloride hexahydrate 0.025 g, Dissolve in deionized water and make up to 100 mL. The pH value of the solution is adjusted to 7.2.
- Test temperature: 24.5 - 25.7 °C
- pH: 7.1 - 7.2 (acceptable range: 6.0 - 8.5)
- Continuous darkness: yes
Other: The biodegradation test was conducted according to the SOP of “Biodegradation test” and the oxygen uptake was measured by the BOD meter equipped with 6 bottles. Reference compound, Sodium benzoate, was used to check the microbial activity of treated inoculums. Test substance and reference compound were treated to be about 100 mg/L(w/v) (16.05 mg and 16.02 mg, respectively) after correcting for purity.


TEST SYSTEM
- Culturing apparatus: Incubator: JEIO TECH Co., Ltd., IL-21, Korea
- Number of culture flasks/concentration: 3 bottles were treated with test item, and 3 bottles served as controls
- Measuring equipment: BOD meter: WTW, OxiTop® Control 6, Germany

SAMPLING
- Sampling frequency: The test was performed in the incubator to maintain a constant temperature and the oxygen uptake was checked once a day during test period.
- Sample storage before analysis: no storage indicated

CONTROL AND BLANK SYSTEM
- Inoculum blank: Activated sludge 5.1 mL + basal culture medium 1.92 mL + deionized water 152.82 mL + Nitrification inhibitor (C4H8N2S) 0.16 mL
- Abiotic sterile control: Test substance (16.05 mg) + deionized water 160 mL
- Toxicity control: no
- Other: Activity control: Sodium benzoate (16.02 mg) + Activated sludge 5.1 mL + basal culture medium 1.92 mL + deionized water 152.82 mL + Nitrification inhibitor (C4H8N2S) 0.16 mL

Reference substance

Reference substance:

benzoic acid, sodium salt

Remarks:

Sodium benzoate

Results and discussion

Test performance:

There was no environmental condition which might have affected the reliability of the test results and the test temperature was maintained at 24.5 - 25.7(25.1±0.2) °C during the test by monitoring of datalogger.

% Degradation

Parameter:

% degradation (test mat. analysis)

Remarks:

residual amount of test substance determined by HPLC-PDA analysis

Value:

4.65

Sampling time:

28 d

Details on results:

BOD concentrations of the inoculum blank (bottle 6) for 28 days were 0.0 - 45.0 mg O2/L.
These values were within the acceptable range (less than 60 mg O2/L for inoculums blank) specified by the OECD guideline.
The change of BOD concentrations for the test bottles was measured by BOD meter for 28 days. The difference of replicate value for the treatments (bottle 2, 3 and 4) at the end of the test was 4.5 % which was less than 20 % specified by the OECD guideline.
The pH values at the end of BOD measurement were 7.21, 7.16 and 7.16 for test bottle 2, 3 and 4, respectively. These values were within the acceptable range (6.0 - 8.5 for pH) specified by the OECD guideline.
The percentage biodegradation of test substance based on BOD measurement were calculated to be 0.0 % after 28 days.
The percentage biodegradations based on the residual amount of test substance by HPLC-PDA analysis was calculated to be 4.65 %.

BOD5 / COD results

Results with reference substance:

The percentage biodegradations of the reference compound (Sodium benzoate) were 76.0 % after 7 days and 77.5 % after 14 days and were within the acceptable range (greater than 40 % after 7 days and 65 % after 14 days) specified by the OECD guideline.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test substance could not be concluded as readily degradable by microorganisms in the aquatic environment. The average percentage biodegradation of the test substance by BOD measurement after 28 days was calculated to be 0.0 % which was less than pass level of biodegradability (60%) specified by the OECD Guideline. The percentage biodegradation based on the residual amount of test substance by HPLC-PDA analysis was calculated to be 4.65 %.

Executive summary:

The biodegradation in water, screening test was performed according to OECD Guideline 301C under GLP compliance. Inoculum used in this study was collected from 11 sites in Korea including 5 rivers (Gangjeong, Mulgeum, Gwangju, Daejeon, Paldang), 4 domestic sewage treatment plants (Dalseo, Gumi, Busan, Jungrang) and 2 industrial wastewater treatment plants(Dalseo, Yeosu). The biodegradation test was conducted according to the SOP of “Biodegradation test” and the oxygen uptake was measured by the BOD meter equipped with 6 bottles. Reference compound, Sodium benzoate, was used to check the microbial activity of treated inoculums. 

The test substance could not be concluded as readily degradable by microorganisms in the aquatic environment. The average percentage biodegradation of the test substance by BOD measurement after 28 days was calculated to be 0.0 % which was less than pass level of biodegradability (60%) specified by the OECD Guideline.

The percentage biodegradations based on the residual amount of test substance by HPLC-PDA analysis was calculated to be 4.65 %.