Potassium niobate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Reason / purpose for cross-reference:

read-across source

Duration:

24 h

Dose descriptor:

other: El20

Effect conc.:

2 186 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EL10

Effect conc.:

1 105 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

LOELR

Effect conc.:

3 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

NOELR

Effect conc.:

2 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

1 498 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95%-CI: 1286 – 1723 mg/L

Duration:

48 h

Dose descriptor:

other: EL20

Effect conc.:

1 060 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95%-CI: 818 – 1242 mg/L

Duration:

48 h

Dose descriptor:

EL10

Effect conc.:

885 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95%-CI: 633 – 1069 mg/L

Duration:

48 h

Dose descriptor:

LOELR

Effect conc.:

1 333 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

889 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: agglomerates formed, test substance is not stable in the neutralized test medium

Results with reference substance (positive control):

- EC50 (24): 1.97 mg/L
- EC50 (48): < 1.25 mg/L

Table 3: Results of the immobilization test after 24 h and 48 h including recorded parameters.

Loading rate [mg/L]	Volume test solution [mL]	Time [h]	Number immobile/ daphnids inserted				Sum immobile	Sum inserted	Immobilization [%]	Oxygen [mg/L]		pH
			1	2	3	4				Initial	End	Initial	End
889	20	24	0/5	1/5	1/5	0/5	2	20	10	6.9	7.4	6.5	6.9
		48	0/5	1/5	1/5	0/5	2	20	10	5.8	7.4		7.4
1333	20	24	2/5	1/5	0/5	0/5	3	20	15	6.9	7.3	6.5	6.8
		48	3/5	3/5	1/5	1/5	8	20	40	5.9	7.4		7.0
2000	20	24	0/5	0/5	0/5	0/5	0	20	0	6.8	7.8	6.5	6.8
		48	4/5	4/5	3/5	4/5	15	20	75	6.1	8.1		6.7
3000	20	24	3/5	2/5	2/5	2/5	9	20	45	6.8	7.7	6.5	6.8
		48	5/5	5/5	4/5	5/5	19	20	95	6.0	8.1		6.5
4500	20	24	0/5	3/5	1/5	2/5	6	20	30	6.9	8.0	6.5	6.7
		48	5/5	5/5	5/5	5/5	20	20	100	6.0	8.0		6.5
Control		24	0/5	0/5	0/5	0/5	0	20	0	7.1	8.0	7.6	7.4
		48	0/5	0/5	0/5	0/5	0	20	0	6.9	8.0		6.4

Table 4: Results of the chemical analysis

		NC	A	C	E
Nominal loading rate [mg/L]		0	889	2000	4500
Measured concentration [µg/L]
	0 h	< LOQ	114	8.90	504
Before chemical	24 h (aged)	< LOQ	1.63	3.89	183
digestion	24 h (fresh)	0.98*	729	49.4	303
	48 h	< LOQ	260	6.01	2.17
	0 h	< LOQ	120	55.6	395
After chemical	24 h (aged)	< LOQ	15.1	42.8	243
digestion	24 h (fresh)	3.93*	577	277	331
	48 h	2.09*	344	80.9	-

LOQ (Limit of quantification) = 0.5 μg/L

*due to memory effects

Validity criteria fulfilled:

yes

Conclusions:

For the conducted semi-static acute immobilization test with Daphnia magna, applying nominal concentrations of 889 to 4500 mg/L niobium pentachloride, nominal effect levels were calculated:
- 48 h EL50 (nominal): 1498 mg/L (95%-CI: 1286 – 1723 mg/L);
- 48h LOELR: 1333 mg/L;
- 48h NOELR: 889 mg/L.
Due to methodological difficulties, it was not possible to calculate effect concentrations based on measured concentrations. Hence, values are reported based on the nominal loading rates.

Executive summary:

The 48-h acute toxicity of niobium pentachloride to Daphnia magna was studied under the conditions of OECD guideline 202 (semi-static conditions). Daphnids were exposed to a control containing no test substance and niobium pentachloride at nominal loading rates of 889, 1333, 2000, 3000 and 4500 mg/L for 48 h. Immobilization was observed daily. Due to highly variable Nb⁵⁺ concentrations in solution, effect concentrations were based on nominal loading rates. The 48-h EL₅₀ was 1498 mg/L. The 48-h NOELR based on immobilization was 889 mg/L and the LOELR was 1333 mg/L. This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates. However, it was not possible to determine effect levels based on measured effective test substance concentrations. After pH adjustment, the measured Nb⁵⁺concentrations were low and showed high variability. Therefore, no concentration-response relationship could be established. Concentrations of the test sample varied due to precipitation, agglomeration and adsorption reactions. In addition, slight changes in pH had profound impact on the test concentrations. Observed immobilization effects may predominantly refer to elevated NaCl concentrations, originated from neutralization, than released Nb⁵⁺ions. Reported EC₅₀values for NaCl vary but may be as low as 874 mg/L (ECHA registry for NaCl). Due to a concentration of approximately 4.68 g/L NaCl, present at the highest loading rate of 4500 mg/L test substance, and the sensitivity of D. magna to salinity, any hypothetical Nb⁵⁺related effects cannot be distinguished from NaCl induced inhibition in the conducted test.

Results Synopsis

 

Test Organism Age: < 24 h

Test Type: Semi-static

	24 h	48 h
ELR50 (nominal)	n.d.	1498 mg/L (95%-CI: 1286 – 1723 mg/L)
ELR20 (nominal)	2186 mg/L (95%-CI: n.d.)	1060 mg/L (95%-CI: 818 – 1242 mg/L)
ELR10 (nominal)	1105 mg/L (95%-CI: n.d.)	885 mg/L (95%-CI: 633 – 1069 mg/L)
LOELR(nominal)	3000 mg/L	1333 mg/L
NOELR(nominal)	2000 mg/L	889 mg/L

Endpoint Effected: Mobility

This information is used in a read-across approach in the assessment of the target substance.

For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Reason / purpose for cross-reference:

read-across source

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

>= 580 - <= 880 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other:

Remarks:

D. magna

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

>= 440 - <= 880 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: D. magna

Details on results:

Effect range for D. magna is given from n=3 tests. D. magna: arithmetic mean after 48 h exposure is given as 660 mg/L.

Results with reference substance (positive control):

48-h LC50 values for NaCl averaged 1,042 mg/L:To determine whether the results of reference toxicant tests related to the responses observed in the concurrent exposures to ion combinations, LC50 values were calculated for the reference toxicant tests from the first 11 test groups with C. dubia (total of 1,045 ion solutions tested). During this period, 48-h LC50 values for NaCl averaged 1,042 mg/L as Cl2 with a coefficient of variation equal to 24%. The LC50 value from the concurrent reference toxicant test was included as an independent variable for each ion solution and thus considered by the stepwise logistic regression. In this analysis, the reference reference toxicant variable was not selected as being statistically significant, explaining only 0.12 % of the overall variance.From this, we surmised that there was no consistent relationship between the sensitivity of the test organisms (as measured by the reference toxicant test) and the responses of organisms in the concurrent ion exposures. For this reason, the reference toxicant test results were not considered further in subsequent regressions.

Reported statistics and error estimates:

Coefficients of variation for LC50 values for individual ion combinations were typical for acute toxicity tests, with means of 17 % for D. magna (SD = 7.5; range 4.8–31).

The measured ion concentrations in the stock solution differed less than 20 % from nominal concentrations and, thus, calculations are based on nominal values.

To calculate ion concentrations in actual test solutions, the concentrations in the applicable stock solutions were multiplied by the relative proportion of each solution in the test solution. Because the dilution water (MHRW) also contained small concentrations of each ion, these background concentrations were then added to the calculated contributions from the stock solutions.

Validity criteria fulfilled:

not applicable

Conclusions:

Within the frame of analysing statistical models to predict the toxicity of major ions to aquatic invertebrates and freshwater fish the toxicity of KCl to Daphnia manga was assessed. The study was conducted according to U.S. EPA national methods.

Executive summary:

The 48-hr acute toxicity of KCl to Daphnia magna was studied under static conditions. Daphnids were exposed to control, positive control (NaCl), and test chemical at nominal concentrations 10,000, 5,000, 2,500, 1,250 mg a.i./L for 48 hr. Mortality was observed at test termination. The 48-hr LC₅₀was determined with a mean of 660 mg/L for D. magna.

 

Based on the results of this study, KCl would not be classified as toxic to D. magna in accordance with the CLP classification system.

 

This study is classified as acceptable for an acute toxicity study with freshwater invertebrates.

 

Results Synopsis

 

Test Organism Age (e.g. 1^stinstar): < 24 h

Test Type (Flowthrough, Static, Static Renewal): Static

 

Daphnia magna:

LC₅₀:  660 mg a.i./L

Endpoint(s) Effected:  mortality

This information is used in a read-across approach in the assessment of the target substance.

For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Reason / purpose for cross-reference:

read-across source

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

>= 580 - <= 630 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other:

Remarks:

C. dubia

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

>= 580 - <= 760 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other:

Remarks:

C. dubia

Details on results:

Effect range for C. dubia is given from n=3 tests. C. dubia: arithmetic mean after 48 h exposure is given as 630 mg/L.

Results with reference substance (positive control):

48-h LC50 values for NaCl averaged 1,042 mg/L:To determine whether the results of reference toxicant tests related to the responses observed in the concurrent exposures to ion combinations, LC50 values were calculated for the reference toxicant tests from the first 11 test groups with C. dubia (total of 1,045 ion solutions tested). During this period, 48-h LC50 values for NaCl averaged 1,042 mg/L as Cl2 with a coefficient of variation equal to 24%. The LC50 value from the concurrent reference toxicant test was included as an independent variable for each ion solution and thus considered by the stepwise logistic regression. In this analysis, the reference reference toxicant variable was not selected as being statistically significant, explaining only 0.12 % of the overall variance.From this, we surmised that there was no consistent relationship between the sensitivity of the test organisms (as measured by the reference toxicant test) and the responses of organisms in the concurrent ion exposures. For this reason, the reference toxicant test results were not considered further in subsequent regressions.

Reported statistics and error estimates:

Coefficients of variation for LC50 values for individual ion combinations were typical for acute toxicity tests, with means of 17 % for C. dubia (SD = 14; range 0.0–61).

The measured ion concentrations in the stock solution differed less than 20 % from nominal concentrations and, thus, calculations are based on nominal values.

To calculate ion concentrations in actual test solutions, the concentrations in the applicable stock solutions were multiplied by the relative proportion of each solution in the test solution. Because the dilution water (MHRW) also contained small concentrations of each ion, these background concentrations were then added to the calculated contributions from the stock solutions.

Validity criteria fulfilled:

not specified

Conclusions:

Within the frame of analysing statistical models to predict the toxicity of major ions to aquatic invertebrates and freshwater fish the toxicity of KCl to Ceriodaphnia dubia was assessed. The study was conducted according to U.S. EPA national methods.

Executive summary:

The 48-hr acute toxicity of KCl to Ceriodaphnia dubia was studied under static conditions. Daphnids were exposed to control, positive control (NaCl), and test chemical at nominal concentrations 10,000, 5,000, 2,500, 1,250 mg a.i./L for 48 hr. Mortality was observed at test termination. The 48-hr LC₅₀was determined with a mean of 630 mg/L for C. dubia.

 

Based on the results of this study, KCL would not be classified as toxic to C. dubia in accordance with the CLP classification system.

 

This study is classified as acceptable for an acute toxicity study with freshwater invertebrates.

 

Results Synopsis

 

Test Organism Age (e.g. 1^stinstar): < 24 h

Test Type (Flowthrough, Static, Static Renewal): Static

  

Ceriodaphnia dubia

LC₅₀:  630 mg a.i./L

Endpoint(s) Effected:  mortality

This information is used in a read-across approach in the assessment of the target substance.

For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Description of key information

Two studies are available for aquatic invertebrates which can be used for read-across to potassium niobate: Heisterkamp (2015) describes the toxicity of NbCl₅, while Mount (1997) reports the toxicity of KCl. Hence, the main components (Nb and K ions) of the target substance (KNbO₃) are assessed by the mentioned ecotoxicological studies.

 

Mount et al. published a peer-reviewed study in 1997 on the toxicity of several ionic compounds to Daphnia magna and Ceriodaphnia dubia including the substance KCl. This study is rated Klimisch 2. The tests with the daphnids were conducted similar to the OECD test guideline 202. The EC₅₀ values after 48-h of static exposure derived for Daphnia magna and Ceriodaphnia dubia are 660 mg/L and 630 mg/L, respectively.

 

The Study by Heisterkamp (2015) was conducted according to GLP principles and followed the OECD test guideline 202. For the conducted semi-static acute immobilization test with Daphnia magna, applying nominal concentrations of 889 to 4500 mg/L niobium pentachloride, nominal 48-h EL₅₀ based on the nominal loading rate was 1498 mg/L.

However, it was not possible to determine effect levels based on measured effective test substance concentrations. After pH adjustment the measured Nb₅₊ concentrations were low and showed high variability. Therefore, no concentration-response relationship could be established. Concentrations of the test sample varied due to precipitation, agglomeration and adsorption reactions. In addition, slight changes in pH had profound impact on the test concentrations. Observed immobilization effects may therefore rather predominantly refer to elevated NaCl concentrations, originated from neutralization, than released Nb⁵⁺ ions. Reported EC₅₀ values for sodium chloride vary but may be as low as 874 mg/L (ECHA registry for sodium chloride). Due to a concentration of approximately 4.68 g/L NaCl, present at the highest loading rate of 4500 mg/L test substance, and the sensitivity of D. magna to salinity, any hypothetical Nb⁵⁺ related effects cannot be distinguished from NaCl induced inhibition in the conducted test.

This information is used in a read-across approach in the assessment of the target substance.

For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

The key value for chemical safety assessment is derived by calculating the EC₅₀value of KNbO₃for combined effects of niobium and potassium ions upon dissolution of the test substance KNbO₃ in water. According to information from the available water solubility study according to OECD 105, 441 mg/L and 143 mg/L of potassium and niobium, respectively, are released from a nominal loading of 20 g KNbO₃/L. The acute toxicity of KNbO₃ to aquatic invertebrates can be calculated according to the following formula:

Sum(Ci) / EC_50m= Sum (Ci / EC_50i)

With

-       Ci =concentration of component i (weight percentage)

-       EC_50i= EC₅₀value for component i

-       n = number of components

-       EC_50m= EC₅₀of the part of the mixture with test data

The weight percentages of potassium and niobium correspond to 75.5 % and 24.5 %, respectively.Sum (Ci) corresponds to 100 %. Thus, the calculated EC₅₀ for KNbO₃ is approximately 735 mg/L. This value is carried forward in the risk assessment.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

735 mg/L