MoVNbTe mixed oxide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 2021-06-29 to 2021-06-30, with the definitive exposure phase on 2021-06-30 at the test facility

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Test item Mo10V3TeNbO42
Batch number Ex 14402.600
CAS No. 146569-48-4
Active ingredient Niobium trivanadium decamolybdenum tellurium dotetracontaoxide
Purity 87.6 %
Water solubility < 0.2 g/L practically insoluble
Appearance Black solid powder
Expiry date 2026-03-10
Recommended storage Store tightly closed, cool and dry / 20°C

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

Based on the results of the preliminary test (see Annex I for details)
the definitive study was carried out with 5 concentrations within the
range of 10 to 1000 mg a.i./L (with and without ATU) in a geometrical
series and with a dilution factor of √10.
All concentrations were weighed out directly in Erlenmeyer flasks
and stirred overnight in 200 mL ultrapure water.
Triplicates of the control (without ATU) without test item were
included at the beginning and at the end of the replicates without
ATU.
Triplicates of the control (with ATU) without test item were included
at the beginning of the replicates with ATU and at the end of the test.
The reference item Copper (II)-sulfate pentahydrate was tested with
three concentrations within the concentration range 58 - 180 mg/L
and a dilution factor of approximately 1.8 (without ATU).
The reference item N-Methylaniline was tested with three
concentrations within the concentration range 0.1 – 1.8 – 32 mg/L
and a dilution factor of 18 (with and without ATU).
A fresh sample of activated sludge taken from the sewage plant
Hildesheim was used for the test procedure. It was washed twice
and adjusted with chlorine free tap water to a dry sludge
concentration of 3.0 g/L ± 10 %.

Test organisms (species):

activated sludge

Details on inoculum:

- Preparation of inoculum for exposure: Municipal sewage treatment plant of 31137 Hildesheim, Germany
Non-adapted activated sludge from the sewage plant at Pattensen is well suited as it receives predominantly municipal sewage and hardly any industrial chemical waste.
- Receipt: 2021-06-29
- Pretreatment: The sludge was washed twice and adjusted with chlorine free tap water if necessary. The sludge was used within 24 h after sampling.
- Dry sludge concentration: 2.95 g/L, corresponding to 1.48 g/L in the test vessels for replicates without ATU and 2.99 g/L, corresponding to 1.50 g/L in the test vessels for replicates with ATU.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

Not determined

Test temperature:

20.9 °C without ATU, 20.7 °C with ATU

pH:

pH-value of the activated sludge for test without ATU 7.33
pH-value of the activated sludge for test with ATU 7.33
pH-value of the synthetic waste water 7.21

Salinity:

Not determined

Details on test conditions:

TEST SYSTEM
- Test vessel: 5
- 500 mL Erlenmeyer flasks, DIN 12380
- Aeration:Permanent, to keep the dissolved oxygen concentration above 60 - 70 % saturation and to maintain the sludge flakes in suspension.
- Pretreatment: Stirring overnight in 200 mL ultrapure water at 400 rpm

- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 6 (Triplicates at the beginning of the test + triplicates at the end of the test.)
- No. of vessels per reference item Copper-II-Sulfat (replicates): 9 (three concentrations within the range 58 - 180 mg/L and a dilution factor 1.8)
- No. of vessels per reference item N-Methylaniline (replicates): 9 (three concentrations within the range 0.1 - 32 mg/L and a dilution factor 18)
- Composition of test medium:

Test concentrations [mg/L] 10 - 31.6 - 100 - 316 - 1000 mg active ingredient/L corresponding to 11.4 - 36.1 - 114 - 361 - 1142 mg test item/L. The test item was weighed out directly in Erlenmeyer flasks.

Test item concentration
[mg/L]
11.4 36.1 114 361 1142
Active ingredient
concentration
[mg a.i./L]*
10 31.6 100 316 1000
Test item [mg] 5.7 18.1 57.0 181 571
Synthetic waste water [mL] 16
Ultrapure water [mL] Filled up to 250 mL
Inoculum [mL] 250

*) corrected for 87.6 % (w/w) active ingredient (a.i.)


Test item concentration
[mg/L]
11.4 36.1 114 361 1142
Active ingredient
concentration
[mg a.i./L]*
10 31.6 100 316 1000
Test item [mg] 5.7 18.1 57.0 181 571
Synthetic waste water [mL] 16
ATU solution [mL]* 2.5
Ultrapure water [mL] Filled up to 250 mL
Inoculum [mL] 250

*) corrected for 87.6 % (w/w) active ingredient (a.i.)
**) Concentration of the ATU solution: 2.32 g/L
 

The reference item concentration (total respiration) was diluted out of a stock solution.
Dilution Table for the Reference Item (Total Respiration)
Reference item concentration [mg/L] 58 100 180
Stock solution [µL]* 96.7 166.7 300
Synthetic waste water [mL] 16
Demineralized water [mL] Filled up to 250 mL
Inoculum [mL] 250
*) Concentration stock solution: 300 g/L

The reference item concentration (nitrification) was diluted out of a stock solution.

Dilution Table for the Reference Item (Nitrification) without ATU
Reference item concentration [mg/L] 0.1 1.8 32
Stock solution [mL]* 0.05 0.9 16
Synthetic waste water [mL] 16
Demineralized water [mL] Filled up to 250 mL
Inoculum [mL] 250
*) Concentration stock solution: 1 g/L



Dilution Table for the Reference Item (Nitrification) with ATU
Reference item concentration [mg/L] 0.1 1.8 32
Stock solution [mL]* 0.05 0.9 16
Synthetic waste water [mL] 16
ATU solution [mL]** 2.5
Demineralized water [mL] Filled up to 250 mL
Inoculum [mL] 250


*) Concentration stock solution: 1 g/L
**) Concentration of the ATU solution: 2.32 g/L



EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
After 3 h incubation, the oxygen concentration of each control, reference item and test item replicate was determined by means of oximeter every 5 seconds after transferring the solution to the measuring chamber and the oxygen depletion was recorded for at least 5 minutes with the software PreSens Measurement Studio 2.

TEST CONCENTRATIONS

Inhibitions in the Preliminary Tests
A preliminary range finding test (non GLP) was carried out with the test item concentrations of 1 – 10 – 100 – 1000 mg/L with one replicate each. The pH was measured in one replicate with 1000 mg/L test item. The flasks were aerated for 3 hours.

In the preliminary range finding test, additional replicates were prepared to determine the inhibition of nitrification. One replicate each of 1 – 10 – 100 - 1000 mg/L was measured with the addition of Allylthiourea (ATU).

Nominal Test
Item
Concentration
[mg/L]
pH
(test item
in
medium)
Inhibition of
total
respiration
(without
ATU)
[%]
Inhibition of
heterotrophic
respiration
(with ATU)
[%]
Inhibition of
nitrification
[%]
10 - 3 0 6
100 - 7 0 13
1000 7.12 27 32 23

Since there is inhibition of nitrification with certain difference from heterotrophic respiration, the test was need to be performed with the determination of both endpoints.

Reference substance (positive control):

yes

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

361 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

114 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of heterotrophic respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

361 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of nitrification rate

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

575 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: CI (430 - 799 mg/L)

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

372 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of heterotrophic respiration

Remarks on result:

other: CI (130 - 1029 mg/L)

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

585 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of respiration due to nitrification

Remarks:

respiration rate

Remarks on result:

other: CI (285 -1045 mg/L)

Key result

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

976 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration tate

Remarks on result:

other: CI (740- 1103 mg/L)

Key result

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

409 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of heterotrophic respiration

Remarks:

respiration rate

Remarks on result:

other: CI (134 - 1082 mg/L)

Key result

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

1 119 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of respiration due to nitrification

Remarks:

respiration rate

Remarks on result:

other: CI (506 - > 1142 mg/L)

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 142 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 142 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of heterotrophic respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 142 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of nitrification rate

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 1 142 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 1 142 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of heterotrophic respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 1 142 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of nitrification rate

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? Yes

Reported statistics and error estimates:

The EC-values of the test item and the reference item were calculated by sigmoidal dose-response regression (biphasic regression where necessary) and linear regression, respectively, using software GraphPadPrism. Calculation of the confidence intervals for the EC50-value was carried out using standard procedures. The coefficient of variation of the oxygen uptake rates of the control replicates was calculated with standard methods using Excel.

The calculation of the oxygen uptake rates (R) and inhibition of respiration rates (I) was performed according to the guideline.

The NOEC for the oxygen uptake rate was determined with the
software ToxRat Professional as specified below.
The NOEC was determined by calculation of statistical significance
of the oxygen uptake rate in comparison to the control using
statistical standard procedure as normality test (Shapiro-Wilk),
variance homogeneity test (Levene’s test) and a multiple test
(Multiple Sequentially-rejective Median After Bonferroni-Holm for
total respiration, Multiple Sequentially-rejective Welsh-t-test After
Bonferroni-Holm for heterotrophic respiration and Williams Multiple
Sequential t-test for nitrification). Prior to running the multiple test,
a normality test and a variance homogeneity test were performed.
The P-value for all tests was 0.01. The a-value (acceptable
probability of incorrectly concluding that there is a difference) is
a=0.05

 

Oxygen Uptake Rates, Specific Respiration Rates and Inhibition of the Respiration

 

From the oxygen depletion the oxygen uptake rates were calculated in mg O2/L/h, additionally the specific respiration rates based on the dry sludge concentration were calculated in mg O2/g/h. The inhibition of the oxygen uptake rates of the test and reference item concentrations in % was calculated in comparison to the oxygen uptake rates of the control. The results are listed in the tables below.

 

Oxygen Uptake Rates and Specific Respiration Rates of the Total Respiration of the Control

	Repl.	Oxygen  Concentration*	Oxygen Uptake Rate RT	Specific Respiration Rate Rs
		[mg O2/L]	[mg O2/(L×h)]	[mg O2/g×h]
Control	1	5.84	37.6	25.5
	2	5.30	36.2	24.5
	3	5.88	37.2	25.2
	4	6.04	30.1	20.4
	5	6.60	34.6	23.5
	6	6.26	32.8	22.2
	Mean value		34.8	23.6
	Standard deviation		2.6
	CV [%]		7.6

*) determined at start of the measurement

Repl. = Replicate ; CV = Coefficient of variation

 

Oxygen Uptake Rates and Inhibition of the Total Respiration of the Test Item Concentrations

Main constituent Concentration**	Test item Concentration	Repl.	Oxygen  Concentration*	Oxygen Uptake Rate RT	Inhibition	Mean Inhibition
[mg a.i./L]	[mg/L]		[mg O2/L]	[mg O2/(L×h)]	[%]	[%]
10	11.4	1	5.91	36.4	-5	-7
		2	5.77	37.5	-8
		3	6.22	37.7	-8
		4	5.63	37	-6
		5	5.95	37.5	-8
31.6	36.1	1	6.18	36.4	-5	-5
		2	5.94	37.3	-7
		3	5.75	35.3	-1
		4	5.86	37.5	-8
		5	6.49	36.9	-6
100	114	1	6.57	36.3	-4	-3
		2	5.96	36.9	-6
		3	6.14	36.3	-4
		4	6.51	31.6	9
		5	6.24	37.5	-8
316	361	1	6.64	33.9	3	4
		2	6.91	33.4	4
		3	6.37	33.3	4
		4	7.01	33.6	3
		5	6.64	32.7	6
1000	1142	1	7.53	26.8	23	24
		2	6.97	26.5	24
		3	7.42	26.1	25
		4	6.85	27	22
		5	7.60	25.9	26

*) determined at start of the measurement

**) corrected for 87.6 % (w/w) active ingredient (a.i.)

Repl. = Replicate

Oxygen Uptake Rates of the Heterotrophic Respiration of the Control Replicates with ATU

	Rep	Oxygen  Concentration*	Oxygen Uptake Rate RH
		[mg O2/L]	[mg O2/(L×h)]
Control	1	7.59	17.0
	2	7.43	17.1
	3	7.51	16.7
	4	7.58	16.4
	5	7.96	15.6
	6	7.71	16.2
	Mean value		16.5
	Standard deviation		0.5
	CV [%]		3.1

*) determined at start of the measurement

CV = Coefficient of variation

 

Oxygen Uptake Rates and Inhibition of the Heterotrophic Respiration

Main constituent Concentration**	Test item Concentration	Rep	Oxygen  Concentration*	Oxygen Uptake Rate RT	Inhibition	Mean Inhibition
[mg a.i./L]	[mg/L]		[mg O2/L]	[mg O2/(L×h)]	[%]	[%]
10	11.4	1	7.79	17.1	-4	-10
		2	7.72	17.5	-6
		3	6.89	17.2	-4
		4	7.93	19.3	-17
		5	7.65	19.5	-18
31.6	36.1	1	7.00	17.7	-7	-10
		2	7.44	18.0	-9
		3	7.31	17.9	-8
		4	8.06	19.0	-15
		5	7.60	18.6	-13
100	114	1	7.31	18.5	-12	-14
		2	7.41	19.7	-19
		3	7.69	18.8	-14
		4	7.48	18.7	-13
		5	7.66	18.3	-11
316	361	1	7.38	15.3	7	6
		2	7.10	15.8	4
		3	7.53	15.4	7
		4	8.14	15.5	6
		5	7.84	15.1	8
1000	1142	1	7.92	11.8	28	27
		2	8.07	11.2	32
		3	7.91	12.2	26
		4	7.99	12.5	24
		5	8.05	12.1	27

*) determined at start of the measurement

**) corrected for 87.6 % (w/w) active ingredient (a.i.)

Calculated Oxygen Uptake Rates of the Nitrification of the Control

	Rep	Oxygen Uptake Rate RN
		[mg O2/(L×h)]
Control	1	20.6
	2	19.1
	3	20.5
	4	13.7
	5	19.0
	6	16.6
Mean value		18.3
Standard deviation		2.4
CV [%]		13.3

CV = Coefficient of variation

 

Oxygen Uptake Rates and Inhibition of the Nitrification

Main constituent Concentration*	Test item Concentration	Rep	Oxygen Uptake Rate RT	Inhibition	Mean Inhibition
[mg a.i./L]	[mg/L]		[mg O2/(L×h)]	[%]	[%]
10	11.4	1	18.3	0	-4
		2	19.4	-6
		3	19.6	-7
		4	18.9	-3
		5	19.4	-6
31.6	36.1	1	18.2	1	-1
		2	19.1	-4
		3	17.1	7
		4	19.3	-5
		5	18.7	-2
100	114	1	17.5	4	8
		2	18.1	1
		3	17.5	4
		4	12.8	30
		5	18.7	-2
316	361	1	18.5	-1	2
		2	18.0	2
		3	17.9	2
		4	18.2	1
		5	17.3	6
1000	1142	1	14.8	19	21
		2	14.5	21
		3	14.1	23
		4	15.0	18
		5	13.9	24

*) corrected for 87.6 % (w/w) active ingredient (a.i.)

 

Validity criteria fulfilled:

yes

Conclusions:

The NOEC of Mo10V3TeNbO42 for Total Respiration is 316 mg active ingredient/L (361 mg/L).
The EC10 for Total Respiration is 503 mg active ingredient/L (575 mg/L) and the EC50 is > 1000 mg active ingredient/L (> 1142 mg/L).

The NOEC for heterotrophic respiration is 100 mg active ingredient/L (114 mg/L).
The EC10 for heterotrophic respiration is 325 mg active ingredient/L (372 mg/L) and the EC50 is > 1000 mg active ingredient/L (> 1142 mg/L).

The NOEC for nitrification is 316 mg active ingredient/L (361 mg/L).
The EC10 for nitrification is 511 mg active ingredient/L (585 mg/L) and the EC50 is > 1000 mg active ingredient/L (> 1142 mg/L).

Executive summary:

 

A respiration inhibition test with activated sludge according to OECD Guideline No. 209 was carried out withthe test item Mo10V3TeNbO42  from 2021-06-29 to 2021-06-30, with the definitive exposure phase on 2021-06-30 at the test facility. The test system was activated sludge of the municipal treatment plant of 31137 Hildesheim, Germany. Based on the results of the preliminary test, the study was carried out under static conditions with the test item
concentrations 10 - 31.6 - 100 - 316 - 1000 mg active ingredient/L with and without N-Allylthiourea, corresponding to 11.4 - 36.1 - 114 - 361 - 1142 mg test item/L. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours and the inhibitory effects of the test and reference item were determined in comparison to the control respiration rates. The mean inhibition of total respiration for the test item replicates ranged from
-7 % to 24 % (Table 10). The mean inhibition of the heterotrophic respiration for the test item replicates ranged from -14 % to 27 % (Table 12). The mean inhibition of nitrification for the test item replicates ranged from -4 % to 21 % (Table 14).

In order to check the activity of the test system and the test conditions a reference test was carried out with copper (II) sulphate pentahydrate and N-Methylaniline (with and without ATU) as reference item and the reference toxicity was determined. The EC50-value for the reference item copper (II) sulphate pentahydrate was 104 mg/L. The EC50-value for the reference item N-Methylaniline was 2.1 mg/L.

 

 

Endpoints of Mo10V3TeNbO42 for Inhibition of Respiration in [mg Test item/L]

 

	Total Respiration		Heterotrophic Respiration		Nitrification
	EC-values [mg/L]	CI  P = 95 [%] [mg/L]	EC-values [mg/L]	CI  P = 95 [%] [mg/L]	EC-values [mg/L]	CI  P = 95 [%] [mg/L]
NOEC	361	–	114	–	361	–
EC10	575	430 – 799	372	130 – 1029	585	285 – 1045
EC20	976	740 – 1103	409	134 – 1082	1119	506 – > 1142
EC50	> 1142	–	> 1142	–	> 1164	–
EC80	> 1142	–	> 1142	–	> 1164	–

 

 

Description of key information

The NOEC of Mo10V3TeNbO42 for Total Respiration is 316 mg active ingredient/L (361 mg/L).
The EC10 for Total Respiration is 503 mg active ingredient/L (575 mg/L) and the EC50 is > 1000 mg active ingredient/L (> 1142 mg/L).

The NOEC for heterotrophic respiration is 100 mg active ingredient/L (114 mg/L).
The EC10 for heterotrophic respiration is 325 mg active ingredient/L (372 mg/L) and the EC50 is > 1000 mg active ingredient/L (> 1142 mg/L).

The NOEC for nitrification is 316 mg active ingredient/L (361 mg/L).
The EC10 for nitrification is 511 mg active ingredient/L (585 mg/L) and the EC50 is > 1000 mg active ingredient/L (> 1142 mg/L).

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

575 mg/L