Bis(5-oxo-L-prolinato-N1,O2)zinc

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

18 June 2015 to 16 July 2015

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

not specified

Details on inoculum:

- Concentration of sludge: 30 mg/L

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

not specified

Parameter followed for biodegradation estimation:

other: Biochemical oxygen demand

Details on study design:

TEST CONDITIONS
- Test temperature: 22 ± 1 °C
- Apparatus: Ohkura Electric Co. Model OM-3100A (I.D. #:T).

TEST SYSTEM
- Culturing apparatus: Bottles
- Number of culture flasks/concentration: Two flasks test material (test material 100 mg/L + inoculum 30 mg/L + mineral medium).

CONTROL AND BLANK SYSTEM
- Inoculum blank: One inoculum blank (inoculum 30 mg/L + mineral medium).
- Other: One procedure control (sodium benzoate 100 mg/L + inoculum 30 mg/L + mineral medium).

SAMPLING
- Sampling frequency: Days 7, 14, 21 and 28.

Reference substance:

benzoic acid, sodium salt

Parameter:

other: BOD

Value:

73

Sampling time:

28 d

Remarks on result:

other: Std dev. not reported

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

Under the conditions of the study the BOD % biodegradability was 73 %.

Executive summary:

The biodegradability was examined in accordance with the standardised guideline OECD 301F under non GLP conditions. The biochemical oxygen demand (BOD) was measured over a 28 day period during which samples were taken on days 7, 14, 21 and 28.

Under the conditions of the study the BOD % biodegradability was 73 %.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24 March 2016 to 14 April 2016

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Dangerous Chemicals Administration GB/T 21801

Version / remarks:

2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Chemical Registration Center of MEP 301F

Version / remarks:

2013

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: State Environmental Protection Administration of China HJ/T 153-2004

Version / remarks:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: State Environmental Protection Administration of China HJ/T 84-2001

Version / remarks:

2001

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Urban construction industry standard of the People's Republic of China CJ/T 221-2005

Version / remarks:

2006

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Controlled room temperature (15 to 25 °C, below 70 % RH)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: Aeration tank of Liede Sewage Treatment Plant of Guangzhou.
- Method of cultivation: Any coarse particles and impurities were removed from the surface of the sludge, the sludge was washed with the test medium (centrifuged at 1100 g for 10 minutes, repeated four times). The supernatant was decanted and the solids were resuspended in the test medium.
- Storage conditions: The sludge was kept aerated until required.
- Concentration of sludge: 4.0 g/L
- Initial cell/biomass concentration: The inoculum was added to each test vessel to give a final concentration of 28 mg/L suspended solids. The total number of cells in the test system was determined as 2.0 x 10^7 cfu/L by nutirent agar.

Duration of test (contact time):

18 d

Initial conc.:

67 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: 10 mL of solution A was mixed with deionised water, then 1 mL of solutions B, C and D were added to make the final volume up to 1 L with deionised water. Six litres were prepared:
Solution A = KH2PO4 8.50g, K2HPO4.3H2O 28.50 g, Na2HPO4.12H2O 67.15 g and NH4Cl 0.50 g, dissolved in water made up to 1 L, pH 7.40.
Solution B = CaCl2 13.75 g, dissolved in water and made up to 0.5 L.
Solution C = MgSO4.7H2O 11.25 g, dissolved in water and made up to 0.5 L.
Solution D = FeCl3.6H2O 0.125 g, dissolved in water and made up to 0.5 L.
- Test temperature: 21.1 to 22.9 °C
- pH: 7.50 to 7.56 (start of the test), 7.31 to 7.56 (end of the test)
- Suspended solids concentration: 4.0 g/L
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: Bottles
- Number of culture flasks/concentration: Three (bottles 1, 2 and A); 4.5 mg of the test material was weighed directly into each bottle, 362.4 mL of test medium was added to each and mixed ultrasonically for 10 minutes to achieve suspensions. 2.6 mL of inoculum was added to each.
- Method used to create anaerobic conditions: The bottles were stirred and incubated in closed conditions.
- Measuring equipment: OxiTop Control BOD Test System recorded the oxygen uptake of each vessel.

SAMPLING
- Sampling frequency: The OxiTop Control BOD Test System was set to record the oxygen update of each vessel automatically during the experiment.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes 3 bottles contained inoculum and test medium only; (bottle 3, 4 and B): 429.0 mL of test medium was added to 3.0 mL of inoculum for each bottle.
- Toxicity control: Yes one control contained test material, reference material, inoculum and test medium; (bottle 6) 16.8 mg of the test material was weighed directly into bottle 6, 241.4 mL of test medium was added and mixed ultrasonically for 10 minutes to form a suspension. 6.9 mL of reference substance stock solution was added and 1.75 mL of inoculum was also added.
- Other: The procedure control contained the reference substance, inoculum and test medium; (bottle 5) 10.0 mL of reference substance stock solution was added to 352.4 mL of test medium and 2.60 mL of inoculum.

CALCULATIONS:
-Calculation of ThOD
The theoretical oxygen demand (ThOD) could be calculated according to the chemical composition. For the compound: CcHhClclNnNanaOoPpSs, the ThOD without nitrification would be:

ThOD NH4 = [16[2c + 0.5 (h-cl-3n)+3s +2.5p+0.5na-o]] / MW

And with nitrification would be:

ThOD NO3 = [16[2c + 0.5 (h-cl) +2.5p+0.5na-o]] / MW.

Where
MW=molecular weight.

ThOD NH4 and ThOD NO3 of the test material are 0.76 mg/mg and 1.12 mg/mg, ThOD NH4 of the reference substance is 1.67 mg/mg.

-Calculation of the percentage biodegradation
It was revealed that nitrification occurred in the test material during the test, the percentage biodegradation of procedure control, toxicity control and test suspension from day 1 to day 17 was calculated using the following:

Da = [(BOD-B)/ThOD NO3)] x100

The percentage biodegradation on day 18 was calculated using:

Da = [(BOD - B – Bn)/ThOD NH4] x 100

The percentage biodegradation of the procedure control was calculated by:

Da = [(BOD – B)/ThOD NH4] x 100

Where:
Da = percentage biodegradation %
BOD = Biological oxygen demand of the test suspension mg/L
B = Oxygen consumption of the inoculum blank mg/L
Bn = Oxygen consumption from nitrification of the test substance mg/L


Calculation of the Primary biodegradation
The primary biodegradation was calculated by the residual amount of the test substance:

Db = [(Sa – Sb) / Sa] x 100

Where:
Db = primary biodegradation %
Sa = the residual amount of the test substance in the test suspensions at the start of the test mg/L
Sb = the residual amount of the test substance in the test suspensions at the end of the test mg/L

Reference substance:

benzoic acid, sodium salt

Test performance:

VALIDITY OF THE TEST
- The oxygen uptake of the inoculum blank was 11.0 mg/L on day 18, from the curve on day 28 it would be less than 60 mg/L and therefore met the validity of the test.
- At the end of the test the pH was 7.31 to 7.56 which was within the acceptance range (6.0 to 8.5).
- The difference of extremes of replicate values of the removal of test material was less than 20 % during the test.
- The percentage biodegradation of the procedure control and the toxicity control were 83.2 and 83.8 % which had reached the pass levels of 60 and 25 % of ThOD within 14 days.

Key result

Parameter:

% degradation (O2 consumption)

Value:

90.7

Sampling time:

18 d

Remarks on result:

other: Standard deviation not reported.

Details on results:

BOD percentage biodegradation:
-Procedure control (14 d): 83.2 %
-Procedure control (18 d): 85.0 %
-Toxicity control (14 d): 83.8 %
-Toxicity control (18 d): 90.9 %
-Test suspension (18 d): 88.0 and 93.3 % = 90.7 % (average)
-Primary biodegradation of test suspensions 1 and 2 were both 100 % on day 18.

-At the end of the test the pH values of the suspensions were 7.31 and 7.33 and the inoculum blanks were both 7.43. The pH values of the procedure control and the toxicity control were 7.56 and 7.47, respectively.

-The results revealed that significant nitrification occurred in the test suspensions 1 and 2 during the test, oxygen consumption from nitrification of the test substance was 21.6 and 21.2 mg/L, respectively.

-On day 14 of the test, the percentage biodegradation of the procedure control and the toxicity control were 83.2 and 83.8 % respectively, which showed that the inoculum activity met the validity of the test, and the test substance was considered not to have a toxic effect of the sewage sludge microorganisms used in the study.

-On day 18 of the test, BOD of the test suspensions 1 and 2 were 77.4 and 79.7 mg/L respectively and the data after that was over the measuring range (80 mg/L) which cannot be read so the test was ended early. The test material residual contents were examines and they were shown to have almost completely biodegraded on day 18.

Results with reference substance:

The percentage biodegradation of the procedure control was 83.2 %.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the conditions of the study, the percentage biodegradation of the test material was greater than 80 % at the end of the 10 day window and the average percentage biodegradation on day 18 was 90.7 %.

Executive summary:

The biodegradability of the test material was determined in accordance with OECD 301F and other Chinese guidelines by measuring oxygen uptake under GLP conditions.

A measure volume of inoculated mineral medium containing a known concentration of test material as a nominal sole source of organic carbon was stirred in a closed bottle at 22 ± 1 °C for up to 28 days. The consumption of oxygen was determined by measuring the change in pressure in the apparatus. Evolved carbon dioxide was absorbed by sodium hydroxide. The amount of oxygen uptake by the microbial population during biodegradation of the test substance was expressed as a percentage of ThOD.

The filtered test material suspension was used for concentration analysis using HPLC, the results showed that the percentage recovery was 99.1 % revealing that the extraction and analysis methods were satisfactory.

On day 18 of the test, BOD of the test suspensions 1 and 2 were 77.4 and 79.7 mg/L respectively and the data after that was over the measuring range (80 mg/L) which cannot be read so the test was ended early. The test material residual contents were examines and they were shown to have almost completely biodegraded on day 18.

All validity criteria of the test were fulfilled.

Under the conditions of the study, the percentage biodegradation of the test material was greater than 80 % at the end of the 10 day window and the percentage biodegradation on day 18 was 90.7 %.

Description of key information

Under the conditions of the study, the percentage biodegradation of the test material was greater than 80 % at the end of the 10 day window and the percentage biodegradation on day 18 was 90.7 %.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Key study- Yanzhen, 2016

The biodegradability of the test material was determined in accordance with OECD 301F and other Chinese guidelines by measuring oxygen uptake under GLP conditions. The study was awarded a reliability score of 2 in accordance with the criteria set forth by Klimisch et al. (1997).

A measure volume of inoculated mineral medium containing a known concentration of test material as a nominal sole source of organic carbon was stirred in a closed bottle at 22 ± 1 °C for up to 28 days. The consumption of oxygen was determined by measuring the change in pressure in the apparatus. Evolved carbon dioxide was absorbed by sodium hydroxide. The amount of oxygen uptake by the microbial population during biodegradation of the test substance was expressed as a percentage of ThOD.

The filtered test material suspension was used for concentration analysis using HPLC, the results showed that the percentage recovery was 99.1 % revealing that the extraction and analysis methods were satisfactory.

On day 18 of the test, BOD of the test suspensions 1 and 2 were 77.4 and 79.7 mg/L respectively and the data after that was over the measuring range (80 mg/L) which cannot be read so the test was ended early. The test material residual contents were examines and they were shown to have almost completely biodegraded on day 18.

All validity criteria of the test were fulfilled.

Under the conditions of the study, the percentage biodegradation of the test material was greater than 80 % at the end of the 10 day window and the percentage biodegradation on day 18 was 90.7 %.

Supporting study- Ichikawa (2015)

The biodegradability was examined in accordance with the standardised guideline OECD 301F under non GLP conditions. The study was awarded a reliability score of 4 in accordance with the criteria set forth by Klimisch et al. (1997). The biochemical oxygen demand (BOD) was measured over a 28 day period during which samples were taken on days 7, 14, 21 and 28.

Under the conditions of the study the BOD % biodegradability was 73 %.