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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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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 guidelineopen allclose all
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)

Test material

Constituent 1
Chemical structure
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 concentrationsopen allclose all
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
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
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
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.

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.