Ruthenium trichloride hydrate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

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)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Control and all test concentrations
- Sampling method: Samples taken at test start and test end
- Sample storage conditions before analysis: The samples were filtered (0.2 μm polyether sulphone membrane syringe filter) at room temperature (20-25°C). The solutions (20 mL) were then transferred into disposable polyethylene vials, acidified with HNO3 (final concentration about 10 %) and stored in a refrigerator (about 4 °C) until further analysis

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Direct addition of the test item to the test medium. Amounts of 20.1, 10.0, 5.0, 2.5 and 1.26 mg of the test item were weighed into a flask, which was subsequently filled up with 1.0 L of AAP medium. The solutions were stirred vigorously using a magnetic stirring bar for about 1 h at room temperature (ca. 20 °C). Afterwards all test solutions were stained brown. To separate insoluble test item from the test medium and to sterilise the test medium, the test medium was filtered using a 0.22 μm PES filter (polyethylensulfone, Nalgene, bottle top filter) under sterile conditions, before addition of the algae. After the filtration step all solutions were clear.
- Controls: Test medium
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): None
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)): None
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): None after filtering

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: unicellular green alga
- Strain: Raphidocelis subcapitata, Chlorophycea, Chlorophyta. (former names Pseudokirchneriella subcapitata, Selenastrum capricornutum)
- 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.
- Age of inoculum (at test initiation): The culture duration of the pre-cultures was 3 days.

ACCLIMATION
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: Not stated

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

Not stated

Test temperature:

21.5 - 22 °C

pH:

Test start: 4.13 - 7.21
Test end: 4.35 - 8.81

Dissolved oxygen:

Not stated

Salinity:

Not stated

Conductivity:

Not stated

Nominal and measured concentrations:

Nominal concentration: 1.25, 2.50, 5.00, 10.0 and 20.0 mg/L, equivalent to: 0.507, 1.01, 2.02, 4.06 and 8.11 mg Ru/L.
Measured concentration at the test start: 0.124, 0.078, 0.091, 0.148 and 1.01 mg Ru/L

The test item concentrations were assessed by chemical analyses of ruthenium in the aqueous phase at the start and at the end of the test and the test item concentrations were calculated based on the ruthenium content of 40.56 %.

Measured concentrations at test start: 0.124, 0.078, 0.091, 0.148 and 1.01 mg Ru/L
Measured concentration after 72 hours: 0.096, 0.072, 0.087, 0.132, 0.575 mg Ru/L
Mean measured concentrations: 0.109, 0.075, 0.089, 0.140, 0.763 mg Ru/L; equivalent to 0.268, 0.184, 0.219, 0.345, 1.882 mg test item /L

The values measured in the test solution represent the soluble part of ruthenium. The deviation from the measured initial ruthenium concentration was greater than ± 20 % at test end and therefore the evaluation of the results was based on the geometric mean test item concentrations

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL conical flasks
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 250 mL conical glass flasks covered with air-permeable silicone-sponge caps
- Aeration: Not stated
- Renewal rate of test solution (frequency/flow rate): None
- Initial cells density: 10 000 cells /mL
- Control end cells density: 161.5 x 10(4) cells/mL
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 8

GROWTH MEDIUM
- Standard medium used: Yes, AAP growth medium. In this medium, the molar ratio of iron to EDTA slightly exceeds unity with iron in excess (molar ratio Fe(III+) / EDTA = 1 / 1.36). Considering the molar ratio of Fe and EDTA and the high stability constant of EDTA with Fe(III+) ions (log Ks 25), the chelation of ruthenium remains negligible in comparison with nominal ruthenium test concentrations and therefore the EDTA containing OECD medium can be used without limitations.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: The pH of the medium was obtained at equilibrium between the carbonate system of the medium and the partial pressure of CO2 in atmospheric air.
- Photoperiod: Continuous light
- Light intensity and quality: 93.68 - 99.81 µE(1) m(-2)s
- Salinity (for marine algae): Not applicable

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter (CASY® TT, Innovatis, Germany).

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Justification for using less concentrations than requested by guideline: Not applicable
- Range finding study: Yes, two pre-tests were conducted.
- Test concentrations:
Pre-test 1: 2.47, 24.7 and 247 μg test item/L (nominal) (1, 10 and 100 μg Ru/L)
Pre-test 2: 247, 991 and 3959 μg test item/L (nominal)
- Results used to determine the conditions for the definitive study: The concentrations to be tested in the definite test were selected on the basis of the results from the range-finding test

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.602 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence intervals: 0.531 - 0.708 mg/L

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.233 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence intervals: 0.206 - 0.259

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 0.184 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: growth rate and yield

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.244 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Details on results:

- Observation of abnormalities (for algal test): Cell debris, barely intact cells at 1.88 mg test item/L

Validity criteria fulfilled:

yes

Remarks:

Cell number in controls increased by a factor of 161.5, mean replicate coefficient of variance was 9.59%, coefficient of variation of average specific growth rate at test end was 0.93%

Conclusions:

The 72-h EC50 based on growth rate was 0.602 mg L-1 and the EC10 was 0.233 mg/L. The 72-h EC50 based on yield was 0.244 mg L-1 and the EC10 could not be determined. The NOEC for growth rate and yield was <0.184 mg L-1.

Executive summary:

A GLP- compliant 72-h algal growth inhibition study was conducted for ruthenium trichloride (hydrate) following OECD guideline 201 (Wenzel 2016).

Two pre-tests were conducted followed by a definitive test with nominal concentrations of 1.25, 2.50, 5.00, 10.0 and 20.0 mg test item L-1, prepared in sterile AAP growth medium. Test solutions were analysed for ruthenium using ICP-OES and mean measured concentrations of 0.268, 0.184, 0.219, 0.345 and 1.882 mg test item L-1 used for reporting of results.

There were concentration-dependent effects on the growth of the green algae over the range of the tested concentrations. The 72-h EC50 based on growth rate was 0.602 mg L-1 and the EC10 was 0.233 mg/L. The 72-h EC50 based on yield was 0.244 mg L-1 and the EC10 could not be determined. The NOEC was calculated to be below the lowest test concentration of 0.184 mg L-1.

Description of key information

The 72-h EC50 based on growth rate was 0.602 mg L-1 and the EC10 was 0.233 mg L-1. The 72-h EC50 based on yield was 0.244 mg L-1 and the EC10 could not be determined. The NOEC for growth rate and yield was <0.184 mg L-1.

Additional information

A GLP- compliant 72-h algal growth inhibition study was conducted for ruthenium trichloride (hydrate) following OECD guideline 201 (Wenzel 2016).

Two pre-tests were conducted, followed by a definitive test with nominal concentrations of 1.25, 2.50, 5.00, 10.0 and 20.0 mg test item L-1, prepared in sterile AAP growth medium. Test solutions were analysed for ruthenium using ICP-OES and mean measured concentrations of 0.268, 0.184, 0.219, 0.345 and 1.882 mg test item L-1 used for reporting of results.

There were concentration-dependent effects on the growth of the green algae over the range of the tested concentrations. The 72-h EC50 based on growth rate was 0.602 mg L-1 and the EC10 was 0.233 mg L-1. The 72-h EC50 based on yield was 0.244 mg L-1 and the EC10 could not be determined. The NOEC was calculated to be below the lowest test concentration of 0.184 mg L-1.