Diammonium sodium hexakis(nitrito-N)rhodate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Samples taken at test start and end from all test concentrations and control.
- Sampling method: Due to turbidity, test media in the two highest test concentrations was filtered before use in the algal test and sampling

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)

- Method: The test item was dissolved in growth medium and diluted with growth medium to obtain the required test concentrations under sterile conditions. The highest test concentration was prepared by adding the appropriate amount of test substance to the dilution water and vigorously stirring for 1 hour at 20°C. An aliquot of this test solution was then diluted further to prepare the other test concentrations.
- Controls: Dilution water only
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): None used

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Source (laboratory, culture collection): SAG, Culture Collection of Algae at Pflanzenphysiologisches, Institut of the University at Göttingen, Albrecht von Haller, Institut, Untere Klarspüle 2, D-37073 Göttingen, Catalog No 61.81 SAG
- Method of cultivation: Prior to testing a pre-culture was established in standard OECD growth medium to obtain exponentially-growing algae for the test. The culture duration of the pre-cultures was 3 days.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22.0 -22.1°C

pH:

pH of the controls: 8.03 at test start and 7.81 at test end (mean)
pH in test cultures: 7.3 - 8.07 at test start and 7.17 - 7.95 at test end (mean)

Details on test conditions:

TEST SYSTEM

- Test vessel: 200 mL conical glass flasks covered with air-permeable silicone sponge caps. Test vessels were cleaned using a dishwasher and additionally rinsed six times with purified water. Test vessels and caps were sterilised by autoclaving prior to use.
- Renewal rate of test solution (frequency/flow rate): Static
- Initial cells density: 10,000 cells/mL
- Control end cells density: 1,832,880 cells/mL
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 8

GROWTH MEDIUM

- Standard medium used: yes – OECD 201 growth medium

OTHER TEST CONDITIONS

- Sterile test conditions: yes
- Adjustment of pH: No
- Light intensity and quality: 92.65 – 98.29 µMol s-1 m-2

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):

- Determination of cell concentrations: measured at 24, 48 and 72 hours using an electronic particle counter

TEST CONCENTRATIONS

- Spacing factor for test concentrations: 3.2
- Range finding study: Concentrations based on a previous definitive test (Wenzel 2015a)
- Results used to determine the conditions for the definitive study: Yes

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

4.5 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 4.23 - 4.78 mg/L

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

0.782

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 0.705 - 0.862 mg/L

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.313 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 0.273 - 0.356 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 0.301 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.522

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Remarks on result:

other: 95% CL 0.477 - 0.568 mg/L

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

0.131 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Remarks on result:

other: 95% CL 0.109 - 0.155 mg/L

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

< 0.301 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 0.301 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.656 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 0.616 - 0.696

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.046 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 0.040 - 0.052

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 0.044 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.076 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

other: Yield

Remarks on result:

other: 95% CL 0.069 - 0.083

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

< 0.044 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

other: Yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 0.044 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

other: Yield

Results with reference substance (positive control):

ErC50: 2.62 mg/L(August 2015). Result is in good agreement with an international ring test

Reported statistics and error estimates:

EC50, EC20 and EC10, and the respective 95% confidence intervals, were calculated using Probit-analysis assuming log-normal distribution of the values. The NOEC values for growth rate were determined by the Williams Multiple Sequential t-test and the NOEC values for yield were calculated by the Mediantest (2-by-2-table) with Bonferroni correction, both using the computer program ToxRat Professional.

Table 1: Effective concentrations of Diammonium sodium hexakis (nitrito-N) rhodate for the exposure of Pseudokirchneriella subcapitata for 72 hours
Parameter	EC50 [mg/L]	EC20 [mg/L]	EC10 [mg/L]	NOEC [mg/L]
Measured initial concentrations [mg test item/L]
Growth rate (r) Value	4.5	0.782	0.313	<0.301
Yield (y) Value	0.522	0.131	<0.301	<0.301
Table 2: Effective concentrations in terms of rhodium concentrations for the exposure of Pseudokirchneriella subcapitata for 72 hours
Parameter	EC50 [mg/L]	EC20 [mg/L]	EC10 [mg/L]	NOEC [mg/L]
Measured initial concentrations [mg test item/L]
Growth rate (r) Value	0.656	0.114	0.046	<0.044
Yield (y) Value	0.076	0.019	<0.044	<0.044

Validity criteria fulfilled:

yes

Remarks:

The cell no. in controls inc. by a factor of 183. The mean of replicate coefficients of variations in section-by-section growth rate of controls - 14.2%. The coefficient of variation of average specific growth rate at test end in replicate control - 2.4%.

Conclusions:

The 72-hour EC50, EC10 and NOEC were found to be 4.5, 0.313 and < 0.301 mg test item L-1, respectively, for growth rate.

Executive summary:

The effect of diammonium sodium hexakis (nitrito-N) rhodate on the growth rate and yield of Pseudokirchneriella subcapitata was investigated according to OECD guideline 201 and EEC method C.3 (Wenzel 2015). Algae were placed in test medium containing the test item at 7 nominal concentrations ranging from 0.20 to 214.7 mg test item L^-1, corresponding to nominal rhodium concentrations of 0.029 to 31.3 mg Rh L^-1. The test was conducted under static conditions for 72 hours. The test solutions were analysed for rhodium using ICP-OES and test results reported based on measured initial concentrations.

The 72-hour EC50, EC10 and NOEC were found to be 4.5, 0.313 and < 0.301 mg test item L^-1 (0.656, 0.046 and <0.044 mg Rh L^-1), respectively, for growth rate. For yield, the EC50, EC10 and NOEC were 0.522, <0.301 and <0.301 mg test item L^-1 (0.076, <0.044 and <0.044 mg Rh L^-1), respectively.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Qualifier:

according to guideline

Guideline:

other: EEC method C.3

GLP compliance:

yes (incl. QA statement)

Remarks:

WCA-003/4-10/A

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Samples taken at test start and end from all test concentrations and control
- Sampling method: Due to turbidity, test media in the two highest test concentrations was filtered before use in the algal test and sampling

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test item was dissolved in growth medium and diluted with growth medium to obtain the required test concentrations under sterile conditions. The highest test concentration was prepared by adding the appropriate amount of test substance to the dilution water and vigorously stirring for 1 hour at 20°C. An aliquot of this test solution was then diluted further to prepare the other test concentrations.
- Controls: Dilution water only
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): None used

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Source (laboratory, culture collection): SAG, Culture Collection of Algae at Pflanzenphysiologisches, Institut of the University at Göttingen, Albrecht von Haller, Institut, Untere Klarspüle 2, D-37073 Göttingen, Catalog No 61.81 SAG
- Method of cultivation: Prior to testing a pre-culture was established in standard OECD growth medium to obtain exponentially-growing algae for the test. The culture duration of the pre-cultures was 3 days.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21.5 - 22°C

pH:

pH of the controls: 7.80 at test start and 8.07 at test end.
pH in test cultures: between 7.63 and 7.88 at test start and between 7.78 and 8.04 at the end of the test.

Nominal and measured concentrations:

Nominal concentrations: 0.2, 0.64, 2.05, 6.56, 21.0, 67.1, 214.7 mg test item/L (equivalent to 0.029, 0.093, 0.299, 0.955, 3.06, 9.78, 31.3 mg Rh/L).
The test evaluation was based on measured initial concentrations of Diammonium sodium hexakis (nitrito-N) rhodate: 0.301, 0.961, 3.02, 9.18, 27.7, 65.7, 207 mg test item/L (calculated from the measured initial rhodium concentrations of 0.044, 0.140, 0.440, 1.34, 4.04, 9.57, 30.1 mg Rh/L).

Details on test conditions:

TEST SYSTEM
- Test vessel: 200 mL conical glass flasks covered with air-permeable silicone sponge caps. Test vessels were cleaned using a dishwasher and additionally rinsed six times with purified water. Test vessels and caps were sterilised by autoclaving prior to use.
- Renewal rate of test solution (frequency/flow rate): Static
- Initial cells density: 10,000 cells/mL
- Control end cells density: 1,325,000 cells/mL
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 8

GROWTH MEDIUM
- Standard medium used: yes – OECD 201 growth medium

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: No
- Light intensity and quality: 90.44 – 93.46 µMol m-2 s-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: measured at 24, 48 and 72 hours using an electronic particle counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.5
- Range finding study: Yes, using concentrations of 2, 20 and 200 mg test item L-1
- Results used to determine the conditions for the definitive study: Yes

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 14.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

< 2.28 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 2.28 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 0.332 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

< 0.332 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 2.08 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Details on results:

Results based on yield:
EC50, EC10 and NOEC: <2.28 mg test item/L
EC50, EC10 and NOEC: <0.332 mg Rh/L

Results with reference substance (positive control):

ErC50: 2.62 mg/L(August 2015). Result is in good agreement with an international ring test

Reported statistics and error estimates:

EC50 and EC10, and their respective 95% confidence intervals were calcualted using Probit-analysis assuming log-normal distribution of the values. The NOEC values for growth rate were determined by the Williams Multiple Sequential t-test the NOEC values for yield were calculated by the Mediantest (2-by-2-table) with Bonferroni correction, both using the computer program ToxRat Professional.

Table 1: Effective concentrations of Diammonium sodium hexakis (nitrito-N) rhodate for the exposure of Pseudokirchneriella subcapitata for 72 hours
Parameter	EC50 [mg/L]	EC10 [mg/L]	NOEC [mg/L]
Measured initial concentrations [mg test item/L]
Growth rate (r) Value	>14.3	<2.28	<2.28
Yield (y) Value	<2.28	<2.28	<2.28
Table 2: Effective concentrations in terms of rhodium concentrations for the exposure of Pseudokirchneriella subcapitata for 72 hours
Parameter	EC50 [mg/L]	EC10 [mg/L]	NOEC [mg/L]
Measured initial concentrations [mg Rh/L]
Growth rate (r) Value	>2.08	<0.332	<0.332
Yield (y) Value	<0.332	<0.332	<0.332

Validity criteria fulfilled:

yes

Remarks:

The cell no. in controls inc. by a factor of 133. The mean of replicate coefficients of variations in section-by-section growth rate of controls - 10%. The coefficient of variation of average specific growth rate at test end in replicate control – 4.3%.

Conclusions:

The 72-hour EC50, EC10 and NOEC were found to be >14.3, <2.28 and <2.28 mg test item L-1, respectively, for growth rate.

Executive summary:

The effect of diammonium sodium hexakis (nitrito-N) rhodate on the growth rate and yield of Pseudokirchneriella subcapitata was investigated according to OECD guideline 201 and EEC method C.3 (Wenzel 2015). Algae were placed in test medium containing the test item at 5 nominal concentrations ranging from 2.00 to 78.3 mg test item L^-1, corresponding to rhodium concentrations of 0.219 to 11.4 mg Rh L^-1. The test was conducted under static conditions for 72 hours. The test solutions were analysed for rhodium using ICP-OES and test results reported based on measured initial concentrations. Although the concentrations used in the main study were based on the results from a rangefinder study, it was not possible to determine an EC50 or EC10 for growth rate from the study, with results reported as unbounded values.

The 72-hour EC50, EC10 and NOEC were found to be >14.3, <2.28 and <2.28 mg test item L-1 (>2.08, <0.332 and <0.332 mg Rh L^-1), respectively, for growth rate. For yield, the EC50, EC10 and NOEC were all <2.28 mg test item L^-1 (<0.332 mg Rh L-¹).

Description of key information

The 72-hour EC50, EC10 and NOEC were found to be 4.5, 0.313 and < 0.301 mg test item L-1, respectively, for growth rate.

Key value for chemical safety assessment

EC50 for marine water algae:

4.5 mg/L

EC10 or NOEC for freshwater algae:

0.313 mg/L

Additional information

The effect of diammonium sodium hexakis (nitrito-N) rhodate on the growth rate and yield of Pseudokirchneriella subcapitata was investigated according to OECD guideline 201 and EEC method C.3 (Wenzel 2015a). Algae were placed in test medium containing the test item at 5 nominal concentrations ranging from 2.00 to 78.3 mg test item L^-1, corresponding to nominal rhodium concentrations of 0.219 to 11.4 mg Rh L^-1. The test was conducted under static conditions for 72 hours. The test solutions were analysed for rhodium using ICP-OES and test results reported based on measured initial concentrations. Although the concentrations used in the main study were based on the results from a rangefinder study, it was not possible to determine an EC50 or EC10 for growth rate from the study, with results reported as unbounded values. The 72-hour EC50, EC10 and NOEC were found to be >14.3, <2.28 and <2.28 mg test item L^-1 (>2.08, <0.332 and <0.332 mg Rh L^-1), respectively, for growth rate. For yield, the EC50, EC10 and NOEC were all <2.28 mg test item L^-1 (<0.332 mg Rh L^-1).

During the initial test for growth rate, a 50% effect was not achieved and effects appeared to plateau (at around 35-40%) above a nominal concentration of 12.5 mg L^-1. However, at the lowest test concentration there was a greater than 10% effect, therefore an EC10 or NOEC could not be derived either. For yield, a greater than 50% effect was observed at all exposure concentrations, therefore no EC50 or EC10 could be derived. As neither an EC50 or EC10 value could be determined from the study, the test was repeated with different test concentrations.

In the repeated test, the effect of diammonium sodium hexakis (nitrito-N) rhodate on the growth rate and yield of Pseudokirchneriella subcapitata was investigated according to OECD guideline 201 and EEC method C.3 (Wenzel 2015b). Algae were placed in test medium containing the test item at 7 nominal concentrations ranging from 0.20 to 214.7 mg test item L^-1, corresponding to nominal rhodium concentrations of 0.029 to 31.3 mg Rh L^-1. The test was conducted under static conditions for 72 hours. The test solutions were analysed for rhodium using ICP-OES and test results reported based on measured initial concentrations.

The 72-hour EC50, EC10 and NOEC were found to be 4.5, 0.313 and < 0.301 mg test item L^-1 (0.656, 0.046 and <0.044 mg Rh L^-1), respectively, for growth rate. For yield, the EC50, EC10 and NOEC were 0.522, <0.301 and <0.301 mg test item L^-1 (0.076, <0.044 and <0.044 mg Rh L^-1), respectively.