Palladium monoxide

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

no experimental study is required for this substance based on the outcome of a full TDp assay (cfr. IUCLID Section 4 'Water solubility') and the identified acute and chronic threshold values for ecotoxicity.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting 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)

Specific details on test material used for the study:

Purity: 97.01% Pd(NH3)4Cl2 (based on analyzed Pd content of 42.06%), rest water (Pd content of pure Pd(NH3)4Cl2 = 43.357%).

Analytical monitoring:

yes

Remarks:

concentrations of the test item in the test medium were confirmed by measuring dissolved Pd concentrations by ICP-MS

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) and immediately stabilised
by adding 0.1 mL conc. HNO3 to 10 mL test media. Samples are typically stable for about 24 hours. Samples were analysed on the day of
sampling, and were immediately stored at 4 °C until analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: To prepare a stock solution in growth medium, 10.34 mg of the test item were transferred into
a 1 L sterile glass flask. Sterile growth medium (1 L) and an acetone washed, sterilised star
shaped stirring bar were added to the bottle and the stock solution was stirred vigorously for
1 hours at room temperature (about 20°C). The stock solution was then diluted with sterile growth medium to obtain the required test
concentrations. All work was conducted on a clean bench using sterile equipment.
- Controls: Test medium (without added test item)
- 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): Experimental Phycology and Culture Collection of Algae at the University of Goettingen
(EPSAG), Nikolausberger Weg 18, 37073 Goettingen, Germany. Catalog No 61.81 SAG.
- Age of inoculum (at test initiation): The culture duration of the pre-cultures was about 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:

22.5 - 23 °C

pH:

pH of the controls: mean pH 7.9 at test start, mean pH 7.92 at test end
pH in test solutions: pH 7.46 to 7.66 at test start, pH 7.85 to 8.31 at test end

Dissolved oxygen:

Not stated

Salinity:

Not stated

Conductivity:

Not stated

Nominal and measured concentrations:

range-finder test: Nominal concentration 0.01-0.1-1 mg test item/L
definitive test: Nominal concentrations: control, 6.25, 12.5, 25.0, 50.0 and 100 μg Pd(NH3)4Cl2/L, equivalent to: control, 2.71, 5.42, 10.84, 21.7 and 43.4 μg Pd/L.

Measured concentrations in control: 0.004 µg Pd/L at test start, 0.006 μg Pd/L at test end
Measured concentrations at test start: 1.30, 3.14, 7.38, 15.9 and 36.5 μg Pd/L
Measured concentration after 72 hours (test end): 0.941, 1.93, 4.93, 9.42 and 26.7 μg/L μg Pd/L
Geometric mean of the measured concentrations at test initiation and termination (mean measured): 1.11, 2.46, 6.03, 12.2 and 31.2 μg Pd/L (equivalent to 2.55, 5.68, 13.9, 28.2 and 72.0 μg test item/L).

The values measured in the test solution represent the soluble part of palladium. The test item concentrations were assessed by chemical analyses of dissolved palladium in the aqueous phase and were calculated based on the palladium content of 42.06%

The evaluation was based on the geometric mean measured Pd concentrations, since the measured Pd concentrations were more than 20% below the nominal values.

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL conical glass flasks, acid-washed (10% HNO3) and rinsed six times with purified water
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 250 mL conical glass flasks covered with air-permeable silicone-sponge caps (vessels and silicone-sponge caps sterilised prior to use by autoclaving).
- Aeration: Not stated
- Renewal rate of test solution (frequency/flow rate): None
- Initial cells density: 10 000 cells /mL
- Control end cells density: 84.6 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. The sterilised synthetic growth medium (OECD medium) according to OECD 201 with
reduced EDTA concentration was used as growth medium.
In a pre-test, it was demonstrated that the growth of R. subcapitata in the OECD 201 growth
medium with 50% EDTA concentration fulfils the validity criteria of the OECD 201 guideline
while it did not in an EDTA-free OECD 201 medium. All stock solutions and the medium were
prepared with purified water processed using an ELGA „PURELAB Ultra“. 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.

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: light intensity (OSRAM Standard “cool white”) adjusted to 60 - 120 μE m-2 s-1
(4440 - 8880 lux) close to the surface of the liquid. The light intensity was measured daily
using a cosine (2 π) receptor (LI-250A, LI-COR) in μE m-2 s-1 at level of the test media
surface. measured light intensity 93.25 to 101.70 μE m-2 s-1
- Salinity (for marine algae): Not applicable

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter (CASY TT, OMNI Life Science GmbH & Co. KG, Bremen, Germany)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Justification for using less concentrations than requested by guideline: Not applicable
- Range finding study: Yes
- Test concentrations:
Nominal concentration 0.01-0.1-1 mg test item/L
- Results used to determine the conditions for the definitive study: The nominal 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):

yes

Remarks:

sensitivity of test organism routinely checked using 3,5-dichlorophenol; latest (April 2018) nominal growth rate ErC50=2.61 mg/L (95% CL 2.36-2.89 mg/L) in good agreement with results of international ring test (ErC50 3.38±1.3 mg/L ).

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

9.94 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 9.02-10.7 µg/L

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

6.25 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 5.14-7.15 µg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

5.67 µg/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.:

7.2 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Remarks on result:

other: 95% CL 6.46-11.7 µg/L

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

4.87 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Remarks on result:

other: 95%CL 3.37-5.35 µg/L

Details on results:

Microscopic examinations were performed to verify a normal and healthy appearance of the inoculum culture and to detect any abnormal appearance of the algae (as may be caused by the exposure to the test substance) at the end of the test.
Normal appearance of algal cells in control and two lowest dose treatments throughout test.
At mid dose level, few algal cells with normal appearance + some cell debris.
At highest two doses, very few algal cells with normal appearance + some cell debris.

Validity criteria fulfilled:

yes

Remarks:

cell number in control cultures increased by factor of 84.6 within 72h; mean of replicate CV in section-by-section growth rate of controls was 12.3% during test period; CV of average specific growth rate at test end in replicate control cultures was 2.4%

Conclusions:

The 72-hour ErC10 and ErC50 for the inhibition of growth rate were estimated with 2.71 μg Pd/L (6.25 μg Pd(NH3)4Cl2/L) and 4.31 μg Pd/L (9.94 μg Pd(NH3)4Cl2/L), based on mean measured Pd concentrations.

For yield, EyC10 and EyC50 values of 2.11 and 3.12 μg Pd/L (4.87 and 7.20 μg Pd(NH3)4Cl2/L) were determined, respectively, based on mean measured Pd concentrations.

The NOEC for the inhibition of both growth rate and yield was determined with 2.46 μg Pd/L (5.68 μg Pd(NH3)4Cl2/L), based on mean measured Pd concentrations.

Executive summary:

A GLP compliant study was performed to determine the toxicity of Tetraamminepalladium(2+) dichloride (Pd(NH3)4Cl2) on the growth of the unicellular freshwater green alga Raphidocelis subcapitata (formerly known as Pseudokirchneriella subcapitata). Exponentially-growing cultures of the green alga were exposed to five concentrations of the test item plus a control over several generations under defined conditions for 72 hours according to the OECD guideline 201.

The nominal test concentrations were prepared with sterile growth medium under sterile conditions. For the examination of the inhibition of alga growth, eight replicates of the control (test medium only) and four replicates of each treatment were tested at the nominal concentrations of 6.25, 12.5, 25.0, 50.0, 100 μg Pd(NH3)4Cl2/L plus control (equivalent to 2.71, 5.42, 10.84, 21.7, 43.4 μg Pd/L). The concentrations of dissolved palladium (Pd) in the media were measured at test initiation and test termination by ICP-MS (LOQ = 0.002 – 0.004 μg Pd/L). Measured palladium concentrations were within a range of 48.0 – 84.1% of the nominal concentrations at test start and between 34.7 – 61.6% of nominal at test termination. Thus, the evaluation was based on geometric mean measured Pd concentrations of 1.11, 2.46, 6.03, 12.2 and 31.2 μg Pd/L (equivalent to 2.55, 5.68, 13.9, 28.2 and 72.0 μg Pd(NH3)4Cl2/L).

A steep concentration-dependent inhibiting effect on the growth of the freshwater green algae was observed over the range of the tested concentrations.

The 72-hour ErC10 and ErC50 for the inhibition of growth rate were estimated with 2.71 μg Pd/L (6.25 μg Pd(NH3)4Cl2/L) and 4.31 μg Pd/L (9.94 μg Pd(NH3)4Cl2/L), based on mean measured Pd concentrations.

For yield, EyC10 and EyC50 values of 2.11 and 3.12 μg Pd/L (4.87 and 7.20 μg Pd(NH3)4Cl2/L) were determined, respectively, based on mean measured Pd concentrations.

The NOEC for the inhibition of both growth rate and yield was determined with 2.46 μg Pd/L (5.68 μg Pd(NH3)4Cl2/L), based on mean measured Pd concentrations.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant, guideline study, available as an unpublished report, no restrictions, fully adequate for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples were taken from the test media at test start and after 72 hours. At test start a sample of fresh control media and freshly prepared test media of each treatment were taken prior to distributing the test media to the test containers. After 72 hours samples of the replicate vessels from each treatment were pooled prior to analysis. Samples were taken and filtered (0.2µm). Solutions were acidified with nitric acid (target concentration 3% HNO3) and stored at 4°C until analysis.

Vehicle:

no

Details on test solutions:

A stock solution of 19.87 mg diamminedichloropalladium/L was prepared by dissolving adequate amounts of test item in sterile growth medium in a sterile glass bottle and stirring for one hour. The stock solution was diluted with 10-fold concentrated growth medium and ultrapure water under sterile conditions to obtain the required test concentrations.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: freshwater alga
- Strain: SAG 61.81
- Source (laboratory, culture collection): SAG, Culture Collection of Algae at Pflanzenphysiologisches Institut of the University of Göttingen, Albrecht von Haller Institut, Untere Klarspüle 2, D-37073 Göttingen.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

Not reported

Test temperature:

21 - 22 °C

pH:

At test start: 7.88 - 8.09
At end of test: 7.29 - 8.12

Dissolved oxygen:

Not reported

Salinity:

Not relevant

Nominal and measured concentrations:

Nominal concentrations: Control, 1.24, 2.48, 4.97, 9.94 and 19.87 g DDP/L
corresponding to Control, 0.625, 1.25, 2.5, 5.0 and 10.0 µg palladium/L,
Mean measured (geometric mean) concentrations: Control, 0.140, 0.286, 0.765, 1.33 and 3.56 µg palladium/L,
corresponding to Control, 0.278, 0.569, 1.52,2.65 and 7.08 µg DDP/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Conical flask
- Type: covered with air-permeable silicon sponge caps
- Material, size, headspace, fill volume: Glass, 250 mL containing 100 mL test medium
- Initial cells density: 10,000 cells/mL
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 8

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: sterile ultrapure water

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: No
- Light intensity and quality: OSRAM "day light" 4440 - 8880 Lux (60 - 120 µE/m2/s)
- Shaken at a rate of 100 rpm

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2

- Range finding study: Yes
- Test concentrations: Not reported

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

4.03 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

Diamminedichloropalladium

Basis for effect:

other: yield

Remarks on result:

other: 95% CL 3.58 - 4.85

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

2.84 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

Diamminedichloropalladium

Basis for effect:

other: yield

Remarks on result:

other: 95% CL 2.50 - 3.16

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2.64 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

Diamminedichloropalladium

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

5.88 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

Diamminedichloropalladium

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 5.27 - 6.22

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

3.74 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

Diamminedichloropalladium

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 2.56 - 4.45

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2.64 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

Diamminedichloropalladium

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

2.03 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element

Remarks:

Palladium

Basis for effect:

other: yield

Remarks on result:

other: 95% CL 1.80 - 2.44

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.43 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element

Remarks:

Palladium

Basis for effect:

other: yield

Remarks on result:

other: 95% CL 1.26 - 1.59

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.33 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element

Remarks:

Palladium

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

2.96 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element

Remarks:

Palladium

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 2.65 - 3.13

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.88 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element

Remarks:

Palladium

Basis for effect:

growth rate

Remarks on result:

other: 95% CL 1.29 - 2.24

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.33 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element

Remarks:

Palladium

Basis for effect:

growth rate

Results with reference substance (positive control):

The sensitivity of the test organism is routinely checked using 3,5-dichlorophenol. The nominal ErC50 value of 2.91 mg/L (95% confidence limits 2.35 - 3.63 mg/L) is in good agreement with the results of an international ring test with ErC50 of 3.38 ± 1.30 mg/L.

Reported statistics and error estimates:

Test results were statistically analysed to determine EC values together with 95 % confidence intervals using Probit-analysis assuming log-normal distribution of the values. Individual replicate responses were used for the regression analysis.
The NOEC and LOEC values for growth rate were determined by the Mann-Whitney U-test with Bonferroni correction and for yield by the Williams Multiple Sequential t-test.

Validity criteria fulfilled:

yes

Conclusions:

The 72-hour ErC50 and ErC10 for growth rate were 5.88 and 3.74 μg test item/L, respectively based on mean measured concentrations of diamminedichloropalladium. For yield the EYC50 and EYC10 values were 4.03 and 2.84 μg /L. NOEC for both growth rate and yield were 2.64 μg test item/L.

Based on the mean measured concentrations of dissolved palladium, the EC50 values for growth rate and yield were 2.96 and 2.03 μg Pd/L. The EC10 values were 1.88 and 1.43 μg Pd/L for growth rate and yield, respectively. The NOEC values for both growth rate and yield were calculated to be 1.33 μg Pd/L.

Executive summary:

A GLP compliant, OECD guideline study to assess algal growth was carried out (Fraunhofer 2012). It is considered to be suitable for use as the key study for this endpoint.

Description of key information

No experimental study is required for this substance based on the outcome of a full TDp assay (cfr.

IUCLID Section 4 'Water solubility') and the identified acute and chronic threshold values with other

water soluble palladium substances.

 

GLP compliant studies were performed to determine the toxicity of Diamminedichloropalladium (Wenzel, 2012) and Tetraamminepalladium(2+) dichloride (Wenzel, 2018) on the growth of the unicellular freshwater green alga Raphidocelis subcapitata (formerly known as Pseudokirchneriella subcapitata) during a 72 hours assay according to the OECD guideline 201. The geometric mean EC10 and EC50 values were calculated as 2.26 and 3.57 µg Pd/L, respectively. These are the lowest acute and chronic threshold identified with palladium substances, and serve as basis for acute and chronic ERV derivation.The geomean ECx values of other algal species (S subspicatus and C. reinhardtii) are 1.8 and 2-fold higher than for P subcapitata, respectively (cfr Environmental Read Across Justification document in IUCLID Section 13 for more details).

Key value for chemical safety assessment

EC50 for freshwater algae:

3.57 µg/L

EC10 or NOEC for freshwater algae:

2.26 µg/L

Additional information

No experimental study is required for this substance based on the outcome of a full TDp assay (cfr.

IUCLID Section 4 'Water solubility') and the identified acute and chronic threshold values with other

water soluble palladium substances.

 

GLP compliant studies were performed to determine the toxicity of Diamminedichloropalladium (Wenzel, 2012) and Tetraamminepalladium(2+) dichloride (Wenzel, 2018) on the growth of the unicellular freshwater green alga Raphidocelis subcapitata (formerly known as Pseudokirchneriella subcapitata) during a 72 hours assay according to the OECD guideline 201. Thegeometric mean EC10 and EC50 values were calculated as 2.26 and 3.57 µg Pd/L, respectively.The geomean ECx values of other algal species (S subspicatusandC. reinhardtii)are 1.8 and 2-fold higher than forP subcapitata, respectively (cfr Environmental Read Across Justification document in IUCLID Section 13 for more details).