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Toxicity to aquatic algae and cyanobacteria

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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)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
10-mL samples were taken in duplicate from all test concentrations and blank controls at the beginning and at the end of the test. Prior to analysis, samples were stored at room temperature.
An additional singular reserve samples of 10 mL were taken from all test solutions for possible analysis. If not used, these samples were stored at room temperature for a maximum of three months.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: preparation of test solutions started with a solution of 100 mg test item/L. The test item was completely dissolved in the test medium by careful mixing. The lower test concentrations were prepared by subsequent dilutions of the highest test solution in test medium. The final test solutions were all clear and colourless. After preparation, volumes of 50 mL were added to each replicate of the respective test concentration.
- Controls: test medium without test substance or other additives (blank control) and the highest test concentration without algae (background control)
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): none
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: Selenastrum capricornutum, NIVA CHL 1
- Source (laboratory, culture collection): in-house laboratory culture
- Age of inoculum (at test initiation): not reported
- Method of cultivation: not reported

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions (same as test or not): algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light in a climate room at a temperature of 23 ± 2 °C. Then, 3 days prior to test start, cells from the algal stock culture were inoculated in culture medium at a cell density of 1 x 10^4 cells/mL. This pre-culture was maintained at the same conditions as used in the test.
- Any deformed or abnormal cells observed: not reported
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
24 mg/L as CaCO3
Test temperature:
23 - 24 °C
pH:
8.1 - 10.2
Nominal and measured concentrations:
Nominal concentrations: 0.32, 1.0, 3.2, 10, 32 and 100 mg test item/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 100-mL glass vessels, containing 50 mL of test solution
- Aeration: not reported
- Initial cells density: 1 x 10^4 cells/mL
- Control end cells density: 196.5 x 10^4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6 (blank control), 1 (background control)

GROWTH MEDIUM
- Standard medium used: yes, the M2-medium was used

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water purified by reverse osmosis, and subsequently passed over activated carbon and ion-exchange cartridges
- Total Hardness: 24 mg CaCO3/L
- Intervals of water quality measurement: the pH of test solutions was measured at the beginning and at the end of the test. The temperature was continuously measured in a temperature control vessel.

OTHER TEST CONDITIONS
- Photoperiod: continuous lighting
- Light intensity and quality: light intensity within the range of 85 to 92 μE.m-2.s-1, using a cool-white TLD-lamp of 30 Watt

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: cells were counted using a microscope and a counting chamber at test start. Thereafter, cells densities were determined by spectrophotometric measurement of samples at 720 nm using a Varian Cary 50 single beam spectrophotometer with immersion probe (pathlength of 20 mm).

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Range finding study
- Test concentrations: 0.1, 1.0, 10 and 100 mg test item/L
- Results used to determine the conditions for the definitive study: the expected EC50 for cell growth inhibition was between 1.0 and 10 mg test item/L, and the expected EC50 for growth rate reduction was significantly higher and exceeded 100 mg test item/L.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.15 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
biomass
Remarks on result:
other: Pt concentrations calculated based on % Pt in the test material.
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
4.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% Confidence Interval: 2.1 - 11 mg test item/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2.3 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
biomass
Remarks on result:
other: 95% Confidence Interval: 0.99 - 5.16 mg Pt/L. Pt concentrations calculated based on % Pt in the test material.
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.47 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
growth rate
Remarks on result:
other: Pt concentrations calculated based on % Pt in the test material.
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
52 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% Confidence Interval: 35 - 73 mg test item/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
24.41 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
growth rate
Remarks on result:
other: 95% Confidence Interval: 16.43 - 34.27 mg Pt/L. Pt concentrations calculated based on % Pt in the test material.
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.42 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% Confidence Interval: 0.18 - 0.99 mg test item/L
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.2 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
biomass
Remarks on result:
other: 95% Confidence Interval: 0.085 - 0.46 mg Pt/L. Pt concentrations calculated based on % Pt in the test material.
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% Confidence Interval: 0.21 - 9.2 mg test item/L
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
1.41 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
growth rate
Remarks on result:
other: 95% Confidence Interval: 0.1 - 4.32 mg Pt/L. Pt concentrations calculated based on % Pt in the test material.
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): none reported
Results with reference substance (positive control):
Based on the 72-hour reference study with Selenastrum capricornutum, the EC50 of potassium dichromate for cell growth inhibition and growth rate reduction were determined to be 0.74 mg/L (95% Confidence Interval of 0.58 to 0.93 mg/L) and 1.5 mg/L (95% Confidence Interval of 1.0 to 2.1 mg/L), respectively.
Reported statistics and error estimates:
Statistically significant inhibition of cell growth and reduction of growth rate were both analysed using Bonferroni t-Test (two-tailed, alpha = 0.05) and Tukey's Test (alpha = 0.05).

Table 1. Mean cell densities (x 10^4 cells/mL) measured at 0, 24, 48, and 72 hours of exposure to platinum(2 +) tetraammine diacetate for Selenastrum capricornutum

 Nominal concentration (mg test item/L)     Exposure time (hours)         
 0 24  48  72 
 Blank control  1.0 11.5 69.2 196.5
 0.32  1.0 11.8 70.5 186.8
 1.0  1.0 7.2 46.4 155.8
 3.2  1.0 6.9 37.3 112.7
 10  1.0 5.7 26.1 82.0
 32  1.0 5.3  10.5 18.4
 100  1.0 4.7 5.7 5.5

Table 2. Percentage inhibition of cell growth and mean area under the growth curve (A) after 72 hours of exposure to platinum(2 +) tetraammine diacetate for Selenastrum capricornutum

 Nominal concentration (mg test item/L)    Cell growth (0 - 72 hours)    
 Mean area (A)  % Inhibition
 Blank control 4235.08 
0.32  4156.64  1.9 
1.0  3096.60  26.9 
3.2  2354.80  44.4 
10  1686.28  60.2 
32  537.80  87.3 
100  257.44  93.9 

Table 3. Percentage reduction of growth rate (μ) at 24, 48 and 72 hours of exposure to platinum(2 +) tetraammine diacetate for Selenastrum capricornutum

 Nominal concentration (mg test item/L)    Mean growth rate                

μ (0 - 24 hours)

% reduction 

μ (0 - 48 hours)

% reduction

μ (0 - 72 hours)

% reduction
Blank control 0.10163 - 0.08825 - 0.07329 -
0.32 0.10276 -1.1 0.08864 -0.4 0.07262 0.9
1.0 0.08251 18.8 0.07994 9.4 0.06991 4.6
3.2 0.08064 20.6 0.07541 14.6 0.06546 10.7
10 0.07246 28.7 0.06776 23.2 0.06117 16.5
32 0.06913 32.0 0.04887 44.6 0.04042 44.8
100 0.06478 36.3 0.03629 58.9 0.02349 67.9
Validity criteria fulfilled:
yes
Conclusions:
Based on nominal concentrations, the 72-hour EC50 of platinum(2+) tetraammine diacetate for biomass and growth rate of Selenastrum capricornutum were estimated to be 4.9 mg test item/L (2.3 mg Pt/L) and 52 mg test item/L (24.41 mg Pt/L), respectively. The 72-hour NOEC for biomass and growth rate were determined to be 0.32 mg test item/L (0.15 mg Pt/L), and 1.00 mg test item/L (0.47 mg Pt/L), respectively.
Executive summary:

A 72-hour algal growth inhibition test was conducted with Selenastrum capricornutum for platinum(2+) tetrammine diacetate. The study is reliable without restriction, being GLP-compliant and having followed standard test guidelines (OECD 201 and EU Method C.3).

Based on a range-finding test, six test concentrations were used and these were analysed using ICP-MS. Measured test concentrations, based on the Pt content, were found to be stable and in agreement with nominal concentrations throughout the test (90 – 105 % of nominal). All validity criteria were met.

The 72-hour EC50 for biomass and growth rate were estimated to be 4.9 mg test item/L (2.3 mg Pt/L) and 52 mg test item/L (24.41 mg Pt/L), respectively. The 72-hour NOEC for biomass and growth rate were determined to be 0.32 mg test item/L (0.15 mg Pt/L), and 1.00 mg test item/L(0.47 mg Pt/L), respectively.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Justification for type of information:
1. HYPOTHESIS FOR THE ANALOGUE APPROACH

The general principles applied for read across between metal substances are that ecotoxicity and the potential for adverse environmental effects are based on the metal ion in cases where the counter ions can reasonably be expected to be non-toxic, as is the case for many simple metals salts (e.g. anions such as SO42-, NO3-, OH-, see additional discussion below for Cl- compounds).

When reading across between different metal substances, the oxidation state of the metal ion needs to be carefully considered. For metals, chemical speciation can affect both the fate of the substance in the environment and its toxicity. For some metals (e.g. chromium and arsenic), large differences in environmental toxicity between difference oxidation states have been observed. For platinum substances, the database of ecotoxicity data is not as extensive as for other metal substances, but there may be a difference in toxicity between platinum (II) and platinum (IV) substances.

2. SOURCE AND TARGET CHEMICAL(S)

Source chemical: Platinum(2+) tetraammine diacetate
Target chemical: Tetraammineplatinum dinitrate

3. ANALOGUE APPROACH JUSTIFICATION

For platinum substances, the database of ecotoxicity data is not as extensive as for other metal substances, but there may be a difference in toxicity between platinum (II) and platinum (IV) substances. For this reason, read-across between different substances is limited to metal compounds in which the metal exists in the same oxidation state.

Generally, the strategies applied for read across between metal substances follow the principle that ecotoxicity and the potential for adverse environmental effects are based on the metal ion in cases where the counter ions can reasonably be expected to be non-toxic. There is some indication that for platinum (IV) substances, substances containing a chloro ligand are more toxic than those without a chloro ligand. As there is some evidence that platinum substances with a chloro ligand are more toxic, and this trend has been more clearly shown for other precious metal substances, read across for platinum (II) substances without a chloro ligand is only conducted from other platinum (II) substances without a chloro ligand.

Data for platinum(2+) tetraammine diacetate is therefore read across to tetraammineplatinum dinitrate, as both are platinum (II) substances that do not contain a chloro ligand.
Reason / purpose for cross-reference:
read-across source
Vehicle:
no
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.15 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
biomass
Remarks on result:
other: Pt concentrations calculated based on % Pt in the test material.
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
4.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% Confidence Interval: 2.1 - 11 mg test item/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2.3 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
biomass
Remarks on result:
other: 95% Confidence Interval: 0.99 - 5.16 mg Pt/L. Pt concentrations calculated based on % Pt in the test material.
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.47 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
growth rate
Remarks on result:
other: Pt concentrations calculated based on % Pt in the test material.
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
52 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% Confidence Interval: 35 - 73 mg test item/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
24.41 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
growth rate
Remarks on result:
other: 95% Confidence Interval: 16.43 - 34.27 mg Pt/L. Pt concentrations calculated based on % Pt in the test material.
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.42 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% Confidence Interval: 0.18 - 0.99 mg test item/L
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.2 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
biomass
Remarks on result:
other: 95% Confidence Interval: 0.085 - 0.46 mg Pt/L. Pt concentrations calculated based on % Pt in the test material.
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% Confidence Interval: 0.21 - 9.2 mg test item/L
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
1.41 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
growth rate
Remarks on result:
other: 95% Confidence Interval: 0.1 - 4.32 mg Pt/L. Pt concentrations calculated based on % Pt in the test material.
Validity criteria fulfilled:
yes
Conclusions:
Based on nominal concentrations, the 72-hour EC50 of platinum(2+) tetraammine diacetate for biomass and growth rate of Selenastrum capricornutum were estimated to be 4.9 mg test item/L (2.3 mg Pt/L) and 52 mg test item/L (24.41 mg Pt/L), respectively. The 72-hour NOEC for biomass and growth rate were determined to be 0.32 mg test item/L (0.15 mg Pt/L), and 1.00 mg test item/L (0.47 mg Pt/L), respectively.
Executive summary:

A 72-hour algal growth inhibition test was conducted with Selenastrum capricornutum for platinum(2+) tetrammine diacetate. The study is reliable without restriction, being GLP-compliant and having followed standard test guidelines (OECD 201 and EU Method C.3).

Based on a range-finding test, six test concentrations were used and these were analysed using ICP-MS. Measured test concentrations, based on the Pt content, were found to be stable and in agreement with nominal concentrations throughout the test (90 – 105 % of nominal). All validity criteria were met.

The 72-hour EC50 for biomass and growth rate were estimated to be 4.9 mg test item/L (2.3 mg Pt/L) and 52 mg test item/L (24.41 mg Pt/L), respectively. The 72-hour NOEC for biomass and growth rate were determined to be 0.32 mg test item/L (0.15 mg Pt/L), and 1.00 mg test item/L(0.47 mg Pt/L), respectively.

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)
Deviations:
not specified
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
not specified
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
Samples of the algal populations were removed daily and absorbance values determined for each control and treatment group. Furthermore, water samples were taken from the control and each test groups (the three replicates were pooled) at 0 and 72 hours for quantitative analysis.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: An amount of test material (160 mg) was dispersed in culture medium and the volume adjusted to 500 mL to give a 320 mg/L stock solution. The following stock solutions were then prepared by serial dilution: 160, 80, 40, and 20 mg/L.
An aliquot (250 mL) of each stock solution was then separately mixed with 250 mL of algal suspension to give the test concentrantions of 10, 20, 40, 80 and 160 mg/L.
- Controls: test medium without the test item
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: green algae
- Strain: CCAP 276/20
- Source (laboratory, culture collection): liquid cultures of Scenedesmus subspicatus were obtained from the Culture Centre for Algae and Protozoa (CCAP), Institute of Freshwater Ecology, Ferry House, Ambleside, Cumbria.

HOLDING CONDITIONS PRIOR TO TEST
Cultures were maintained in the laboratory by the replenishment of culture medium approximately once per week. The culture was maintained in the laboratory at a temperature of 21 ± 1 °C under continuous illumination (intensity approximately 7000 lux) and constant aeration.

LIFE STAGE OF TEST SPECIES USED
Pre-culture conditions gave an algal suspension in log phase growth characterised by an absorbance of 1.998 (at 665 nm). This suspension was diluted to an absorbance of 0.030 prior to use. At test start the culture contained a nominal cell density of 1000 cells/mL.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
24 °C
pH:
7.6 - 10.2
Nominal and measured concentrations:
Nominal concentrations: 10, 20, 40, 80 and 160 mg test item/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 mL glass conical flasks
- Type: covered with aluminium foil
- Fill volume: 100 ml of test solution
- Initial cells density: 50000/mL
- Control end cells density: 2000000/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: at approximately 7000 lux
- Test vessels were constantly shaken at 100 rpm

EFFECT PARAMETERS MEASURED: the cell densities of the controls and test concentrations cultures were determined every 24 hours by direct counting with the aid of a haemocytometer and using a spectrophotometer, respectively.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study
- Test concentrations: 0.010, 0.10, 1.0, 10 and 100 mg test item/L
- Results used to determine the conditions for the definitive study: results showed no effect on growth at test concentrations of 0.010, 0.10, 1.0 and 10 mg test item/L. Growth was observed to be reduced at 100 mg test item/L.
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
50.64 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
pt
Basis for effect:
biomass
Key result
Duration:
48 h
Dose descriptor:
EC50
Remarks:
24-48 h
Effect conc.:
280 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Extrapolated value
Duration:
48 h
Dose descriptor:
EC50
Remarks:
24-48 h
Effect conc.:
141.79 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
growth rate
Remarks on result:
other: Extrapolated value
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
40 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
20.25 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
growth rate
Details on results:
The EC50 for growth rate was determined by extrapolation as less than 50 % inhibition occurred over the test concentrations range.
Reported statistics and error estimates:
Statistical analysis of the area under the growth curve was carried out for the control and all test concentrations using one-way analysis of variance. The test concentrations of 60, 80 and 160 mg test item/L were found to be significantly different (p < 0.05) from the control groups.

Table 1. Mean cell density and absorbance values of the control cultures measured every 24 hours

 Control 0 h  24 h  48 h  72 h 
Mean cell density (cells/mL)  5.87 x 104  5.86 x 104 2.59 x 105  2.10 x 106 
Mean absorbance value 0.026  0.035  0.149  0.740 

Table 2. Inhibition of growth determined by tetraammineplatinum (2 +) hydrogencarbonate to Scenedesmus subspicatus

 Nominal concentrations (mg test item/L) Area under curve at 72 h  % inhibition  Growth rate (24 - 48 h)   % inhibition
 Control 11.960  0.063 
10  11.640  0.063 
20  9.752  18  0.060 
40  9.936  17  0.054  14 
80  6.756  44  0.053  16 
160  3.484  71  0.044  30 
Validity criteria fulfilled:
not specified
Conclusions:
Based on nominal concentrations, the 72-hour EC50 of tetraammineplatinum(2+) hydrogencarbonate to Scenedesmus subspicatus was determined to be 100 mg test item/L (50.64 mg Pt/L) for biomass. The 24/48-hour EC50 for growth rate was extrapolated to be 280 mg test item/L (141.79 mg Pt/L).
Executive summary:

A 72-hour algal growth inhibition test was conducted with Scenedesmus subspicatus for tetraammineplatinum(2+) hydrogencarbonate.The study is reliable without restrictions, being GLP-compliant, and having followed standard test guidelines (OECD 201 and EU Method C.3).

Based on a range-finding test, five test concentrations were used and these were analysed using HPLC. Measured test concentrations were found to be in excess of the required 80 % of nominal, and therefore results were based on nominal concentrations. The 72-hour EC50 for biomass was estimated to be 100 mg test item/L (50.64 mg Pt/L), and the 24/48-hour EC50 for growth rate was extrapolated to be 280 mg test item/L(141.79 mg Pt/L). The 72-hour NOEC was determined to be 40 mg test item/L (20.25 mg Pt/L).

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Justification for type of information:
1. HYPOTHESIS FOR THE ANALOGUE APPROACH

The general principles applied for read across between metal substances are that ecotoxicity and the potential for adverse environmental effects are based on the metal ion in cases where the counter ions can reasonably be expected to be non-toxic, as is the case for many simple metals salts (e.g. anions such as SO42-, NO3-, OH-, see additional discussion below for Cl- compounds).

When reading across between different metal substances, the oxidation state of the metal ion needs to be carefully considered. For metals, chemical speciation can affect both the fate of the substance in the environment and its toxicity. For some metals (e.g. chromium and arsenic), large differences in environmental toxicity between difference oxidation states have been observed. For platinum substances, the database of ecotoxicity data is not as extensive as for other metal substances, but there may be a difference in toxicity between platinum (II) and platinum (IV) substances.

2. SOURCE AND TARGET CHEMICAL(S)

Source chemical: Tetraammineplatinum(2+) hydrogencarbonate
Target chemical: Tetraammineplatinum dinitrate

3. ANALOGUE APPROACH JUSTIFICATION

For platinum substances, the database of ecotoxicity data is not as extensive as for other metal substances, but there may be a difference in toxicity between platinum (II) and platinum (IV) substances. For this reason, read-across between different substances is limited to metal compounds in which the metal exists in the same oxidation state.

Generally, the strategies applied for read across between metal substances follow the principle that ecotoxicity and the potential for adverse environmental effects are based on the metal ion in cases where the counter ions can reasonably be expected to be non-toxic. There is some indication that for platinum (IV) substances, substances containing a chloro ligand are more toxic than those without a chloro ligand. As there is some evidence that platinum substances with a chloro ligand are more toxic, and this trend has been more clearly shown for other precious metal substances, read across for platinum (II) substances without a chloro ligand is only conducted from other platinum (II) substances without a chloro ligand.

Data for tetraammine platinum hydrogen carbonate is therefore read across to tetraammineplatinum dinitrate, as both are platinum (II) substances that do not contain a chloro ligand.
Reason / purpose for cross-reference:
read-across source
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
50.64 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
pt
Basis for effect:
biomass
Key result
Duration:
48 h
Dose descriptor:
EC50
Remarks:
24-48 h
Effect conc.:
280 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Extrapolated value
Duration:
48 h
Dose descriptor:
EC50
Remarks:
24-48 h
Effect conc.:
141.79 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
growth rate
Remarks on result:
other: Extrapolated value
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
40 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
20.25 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Pt
Basis for effect:
growth rate
Details on results:
The EC50 for growth rate was determined by extrapolation as less than 50 % inhibition occurred over the test concentrations range.
Validity criteria fulfilled:
not specified
Conclusions:
Based on nominal concentrations, the 72-hour EC50 of tetraammineplatinum(2+) hydrogencarbonate to Scenedesmus subspicatus was determined to be 100 mg test item/L (50.64 mg Pt/L) for biomass. The 24/48-hour EC50 for growth rate was extrapolated to be 280 mg test item/L (141.79 mg Pt/L).
Executive summary:

A 72-hour algal growth inhibition test was conducted with Scenedesmus subspicatus for tetraammineplatinum(2+) hydrogencarbonate.The study is reliable without restrictions, being GLP-compliant, and having followed standard test guidelines (OECD 201 and EU Method C.3).

Based on a range-finding test, five test concentrations were used and these were analysed using HPLC. Measured test concentrations were found to be in excess of the required 80 % of nominal, and therefore results were based on nominal concentrations. The 72-hour EC50 for biomass was estimated to be 100 mg test item/L (50.64 mg Pt/L), and the 24/48-hour EC50 for growth rate was extrapolated to be 280 mg test item/L(141.79 mg Pt/L). The 72-hour NOEC was determined to be 40 mg test item/L (20.25 mg Pt/L).

Description of key information

For tetraammine platinum dinitrate, ecotoxicity data are read across from other Pt(II) substances without a chloro ligand, tetraammine platinum hydrogen carbonate and platinum(2+) tetraammine diacetate. The lowest reported EC50 based on growth rate is 24.4 mg Pt L-1 and the lowest EC10 and NOEC values (growth rate) are 1.41 mg Pt L-1 and 0.470 mg Pt L-1, respectively.

Key value for chemical safety assessment

Additional information

For tetraammine platinum dinitrate, ecotoxicity data are read across from other Pt(II) substances without a chloro ligand, tetraammine platinum hydrogen carbonate and platinum(2+) tetraammine diacetate. 

A 72-hour algal growth inhibition test was conducted with Scenedesmus subspicatus for tetraammineplatinum(2+) hydrogencarbonate following OECD guideline 201 and EU Method C.3 (Mead and Bartlett 1997). Based on a range-finding test, five test concentrations were used and these were analysed using HPLC. Measured test concentrations were found to be in excess of the required 80 % of nominal, and therefore results were based on nominal concentrations. The 72-hour EC50 for biomass was estimated to be 100 mg test item L-1 (50.64 mg Pt L-1), and the 24 - 48-hour EC50 for growth rate was extrapolated to be 280 mg test item L-1 (141.79 mg Pt L-1). The 72-hour NOEC was determined to be 40 mg test item L-1 (20.25 mg Pt L-1).

A 72-hour algal growth inhibition test was conducted with Selenastrum capricornutum for platinum(2+) tetraammine diacetate following OECD guideline 201 and EU Method C.3 (Migchielsen 2006). Based on a range-finding test, six test concentrations were used and these were analysed using ICP-MS. Measured test concentrations, based on the Pt content, were found to be stable and in agreement with nominal concentrations throughout the test (90 – 105 % of nominal). Therefore, results were based on nominal concentrations. All validity criteria were met. The 72-hour EC50 for biomass and growth rate were estimated to be 4.9 mg test item L-1 (2.3 mg Pt L-1) and 52 mg test item L-1 (24.41 mg Pt L-1), respectively. The 72-hour NOEC for biomass and growth rate were determined to be 0.32 mg test item L-1 (0.15 mg Pt L-1), and 1.00 mg test item L-1 (0.47 mg Pt L-1), respectively. The 72 -hour EC10 values for biomass and growth rate were 0.42 mg test item L-1 (0.2 mg Pt L-1) and 3.0 mg L-1 (1.41 mg Pt L-1).