Borate(1-), bis[ethanedioato(2-)-.kappa.O1,.kappa.O2]-, potassium (1:1), (T-4)-

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:

2004-10-25 to 2004-10-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Version / remarks:

. EEC directive 92/69, Part C; Publication No. L383, December 1992

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Version / remarks:

, adopted 1992-07-17

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

244761-29-3

EC Number:

607-383-9

Cas Number:

244761-29-3

IUPAC Name:

244761-29-3

Constituent 2

Reference substance name:

Lithium bis(oxalato)borate

EC Number:

456-990-3

EC Name:

Lithium bis(oxalato)borate

IUPAC Name:

lithium bis(oxalato)borate

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

SMILES: O=C1O[B-]2(OC1=O)OC(=O)C(=O)O2.[Li+]

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

10 mg/L

Based on:

other: nominal concentration of the test item

Initial test substance concentration 2

Initial conc.:

30 mg/L

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral Medium (8.5 mg/L KH2PO4, 21.75 mg/L K2HPO4, 67.20 mg/L Na2HPO4*12 H2O, 0.5 mg/L NH4Cl, 22.5 mg/L MgSO4*7 H2O, 36.4 mg/L CaCl2*2 H2O, 0.25 FeCl3*6 H2O)
- Additional substrate: no
- Test temperature: 21.1 - 22.9 °C
- pH: 7.3-7.6
- pH adjusted: yes, with 1 N NaOH
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 250-300 ml BOD bottles with glass stoppers
- Number of culture flasks/concentration: duplicates
- Method used to create aerobic conditions: The concentration of dissolved oxygen was measured for control purposes. The mineral medium was left at
test temperature to obtain a saturated solution at the start of the test.
- Measuring equipment: oxygen meter

SAMPLING
- Sampling frequency: ln duplicate; immediately at the start of the experiment (day 0), and at day 4, 8, 12, 16, 20, 24 and 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes
- Toxicity control: yes
- Other: positive control: yes: Sodium acetate (2 mg/L)

Reference substance

Reference substance:

acetic acid, sodium salt

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

39

Sampling time:

4 d

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

89

Sampling time:

8 d

% Degradation 3

Parameter:

% degradation (O2 consumption)

Value:

80

Sampling time:

12 d

% Degradation 4

Parameter:

% degradation (O2 consumption)

Value:

83

Sampling time:

16 d

% Degradation 5

Parameter:

% degradation (O2 consumption)

Value:

95

Sampling time:

28 d

Details on results:

The results indicated above refer to 10 mg/L and are mean values from duplicates.
Additional results - that could not be filled in the table above - are as follows: 85 % at day 20 and 89 % at day 24.
The following results refer to 30 mg/L and are mean values: 15 % (4d), 68 % (8d), 77 % (12d), 79 % (16d), 72 % (20d), 82 % (24d), 86 % (28d).

The values of the oxygen depletion (mg BOD/L) (duplicates) at different time points are as follows:
10 mg/L: 0.720 and 0.570 (4 h), 1.400 and 1.530 (8 h), 1.305 and 1.325 (12 h), 1.370 and 1.380 (16 h), 1.460 and 1.330 (20 h), 1.440 and 1.500 (24 h), 1.510 and 1.620 (28 h);
30 mg/L: 1.580 and -0.080 (4 h), 3.480 and 3.290 (8 h), 3.845 and 3.785 (12 h), 3.980 and 3.870 (16 h), 3.500 and 3.600 (20 h), 4.120 and 4.040 (24 h), 4.200 and 4.330 (28 h).

BOD5 / COD results

Results with reference substance:

The following results refer to 2 mg/L reference substance and are mean values: 44 % (4d), 93 % (8d), 79 % (12d), 79 % (16d), 73 % (20d), 75 % (24d), 84 % (28d)

Any other information on results incl. tables

There was no inhibition of microbial activity in the toxicity control.

There was no significant degradation in the abiotic control.

Read across for evaluation of biodegradation of potassium bis(oxalato)borate from the biodegradation study results of lithium bis(oxalato)borate is justified on the basis of structural similarity of the substances. The bis(oxalato)borate salt part [B(C2O4)2] is the same in both substances and only the cationic part of salts differ (lithium or potassium). Both lithium and potassium belong to alkali-metals.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Lithium bis(oxalato)borate was ready biodegradable under the conditions in the closed bottle test and therefore considered to be "ready biodegradable".Based on structural similarity, the result can be used for read across when evaluating biodegradability of potassium bis(oxalato)borate. The result from biodegradation study can be used and is valid for environmental classification of KBOB. For risk assessment, also potassium bis(oxalato)borate can be regarded as readily biodegradable. See also attachment in section 13 (Analogue approach justification).

Executive summary:

A study on biodegradation (closed bottle test) of lithium bis(oxalato)borate was assessed according to OECD guideline 301D and EU method C.4. The relative biodegradation values calculated from the 2 measurements performed during the test period of 28 days revealed 95 % degradation of test substance at 10 mg/L and 86 % degradation of test substance at 30 mg/L. Furthermore, at least 60 % degradation was reached within the 10 days immediately following the attainment of 10 % biodegradation (10-day window). Except for a deviating difference of duplicate values of the reference substance at the end of the test (24 %), which was considered not to have affected the integrity of this study, all criteria for acceptability of the test were met. Therefore, this study was considered to be valid.

Thus, lithium bis(oxalato)borate was ready biodegradable under the conditions in the closed bottle test. (NOTOX, 2004).

Based on structural similarity, the result can be used for read across when evaluating biodegradability of potassium bis(oxalato)borate. Consequently, also potassium bis(oxalato)borate can be regarded as readily biodegradable.