Dirhodium trisulphate

Toxicity to aquatic algae and cyanobacteria

Administrative data

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

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Diammonium sodium hexakis(nitrito-N)rhodate

EC Number:

264-713-0

EC Name:

Diammonium sodium hexakis(nitrito-N)rhodate

Cas Number:

64164-17-6

Molecular formula:

H4N.1/2N6O12Rh.1/2Na

IUPAC Name:

Diammonium sodium hexakis(nitro-N)rhodate

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Sampling and analysis

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

Test solutions

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

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella 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.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

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

Results and discussion

Effect concentrations

Effect concentrations 1

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

Effect concentrations 2

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

Effect concentrations 3

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

Effect concentrations 4

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

Effect concentrations 5

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

Effect concentrations 6

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

Effect concentrations 7

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

Effect concentrations 8

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

Effect concentrations 9

Key result

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

Effect concentrations 10

Key result

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

Effect concentrations 11

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

Effect concentrations 12

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

Effect concentrations 13

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

Effect concentrations 14

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.

Any other information on results incl. tables

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

Applicant's summary and conclusion

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 (corresponding to 0.656, 0.046 and <0.044 mg Rh L-1).

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.