Palladium (II) di(4-oxopent-2-en-2-oate)

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

5 December 2019 - 30 March 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Version / remarks:

Adopted June 18th, 2019

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Pd content: 34.52% (>99.9% Palladium (II) di(4-oxopent-2-en-2-oate) (Pd(C5H7O2)2) based on analysed Pd)

Analytical monitoring:

yes

Details on sampling:

dissolved Pd is determined in samples of all fresh test solutions (at the beginning of the test prior to addition of test organisms and at media renewal after 48 hours, immediately after preparation of test solutions before distributing to the test vessels) and aged samples (before media renewal and at test end).
Duplicate samples were taken (10 mL), filtered (0.45 µm polyethersulphone membrane (PES) syringe filter) and afterwards acidified with conc. HNO3.
Samples were sealed after acidification and stored at ± 4°C is not analysed immediately.

Vehicle:

yes

Remarks:

test item is dissolved in Cu-reduced dilution water

Details on test solutions:

At first a stock solution was prepared by transferring 5.0 mg of the test item into a glass flask. 5000 mL Cu-reduced dilution water and a stirring bar were added to the bottle and stirred vigorously for about 24 hours at room temperature (about 20°C) to achieve maximum solubility of the test item. Another flask was filled with dilution water only for the control replicates and stirred in the same way.
After 24 hours, the stock solution was ultrasonicated for 30 minutes and afterwards undissolved test item was removed using a PES (polyethersulphone) bottle top filter with a pore size of 0.45 µm. The filtrate of the stock solution was diluted with test water to obtain the other test concentrations.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

Test facility-bred. Fertilised eggs for the test were obtained from iindividuals reared in the laboratory of the Fraunhofer Institute, Schmallenberg, Germany.
Origin: West Aquarium GmbH, 37431 Bad Lauterberg, Germany
Size: 1.0 - 2.0 cm

Test type:

semi-static

Water media type:

freshwater

Remarks:

Purified drinking water was used according to the OECD guideline203

Limit test:

no

Total exposure duration:

96 h

Remarks on exposure duration:

Semi-static conditions for a period of 96 h in 3 L test vessels (filled wth about 2L test solution) with one media renewal after 48 hours.

Test temperature:

22.8-23.6 °C

pH:

7.80 - 8.05

Dissolved oxygen:

oxygen saturation 89.0 - 99.0%

Nominal and measured concentrations:

nominal: control, 3.2, 7.04, 15.5, 34.1, 75 µg Test item/L (corresponding to control, 1.11, 2.43, 5.35, 11.8, 25.9 µg Pd/L)
measured (geomean concentrations): control, 1.98, 4.52, 10.4, 24.2, 42.1 µg Test Item/L (corresponding to control, 0.683, 1.56, 3.60, 8.35, 14.5 µg Pd/L)
For calculation of geometric mean concentrations, at first, the measured background concentrations of the control samples were deducted from the measured test item concentration of the respective test concentration.
Measured test item concentrations and calculated geometric mean concentrations used for the effect assessment.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

5.48 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality (fish)

Remarks on result:

other:

Remarks:

95% CI: not determinable

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

15.9 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality (fish)

Remarks on result:

other:

Remarks:

95% CI: not determinable

Details on results:

Prior to test start, a subsample of the fish batch used in the test was weighed out and lengths were measured. The fish lengths were in the range of 1.7 – 2.0 cm. The mean weight resulted in a loading of 0.048 g/L test medium, and therefore was in line with density given by the respective guideline oecd203 (allowed loading: 0.8 g fish/L).
Within the first 24 hours after test start, all fish in the highest concentration of 14.5 µg Pd/L (42.1 µg test item/L) died. After media renewal after 48 hours, all fish in the second highest test concentration of 8.35 µg Pd/L (24.2 µg test item/L) were found dead. No fish died in the three lowest test concentrations of 0.68, 1.56 and 3.60 µg Pd/L (1.98, 4.52 and 10.4 µg test item/L), respectively. In addition, no fish died in the control.
No sublethal effects occurred in any test concentration during the whole exposure period.

Results with reference substance (positive control):

no reference substance included

Reported statistics and error estimates:

Since the test results showed mortality of around 50 %, data were statistically analyzed to determine LC10 and LC50 values together with 95 % confidence intervals using Probit-analysis, assuming log-normal distribution of the values.
The results were calculated using the geometric mean measured concentrations of the test item.
The LC50, the confidence limits (95%) and the slope of the curve were estimated using appropriate statistical methods such as the classical maximum likelihood methods for fitting probit or logit models. All statistics were calculated by using ToxRat® Professional 3.3.0 .

Sublethal observations / clinical signs:

The cumulative mortality observed during the 96 hour exposure period:

	Geometirc mean measured concentration [µg Pd/L]
	Control	0.683	1.56	3.60	8.35	14.5
Fish introduced	7	7	7	7	7	7
h of application	Cumulative mortality [n]
0	-	-	-	-	-	-
3	-	-	-	-	-	-
6	-	-	-	-	-	-
22	-	-	-	-	-	7
28	-	-	-	-	-	7
48	-	-	-	-	1	7
53	-	-	-	-	6	7
70	-	-	-	-	7	7
77	-	-	-	-	7	7
96	-	-	-	-	7	7

- = no mortality detected

Validity criteria fulfilled:

yes

Remarks:

mortality in control <10%, dissolved oxygen >60%, analytical determination dissolved Pd

Conclusions:

The test item Palladium (II) di(4-oxopent-2-en-2-oate) (CAS 14024-61-4) showed a significant effect on the test organism Danio rerio in a 96-hour acute toxicity test under semi-static test conditions. Based on calculated geometric mean Palladium concentrations, the LC50 was calculated to be 5.48 µg Pd/L, equivalent to 15.9 µg test item/L.

Executive summary:

A study was performed to determine the acute toxicity of Palladium (II) di(4-oxopent-2-en-2-oate) (CAS 14024-61-4) to zebrafish (Danio rerio). The study was performed according to the OECD guideline 203 and the EEC method C.1.

The fish were exposed to five test concentrations of the test item under semi-static conditions for a period of 96 hours. Untreated dilution water was run in parallel as a control. Seven fish were placed in each treatment vessel and in the control. The mortality and sublethal effects were determined at least twice per day, with a minimum of two observations within the first 24 hours.

Following test item concentrations were introduced in the test:

3.20, 7.04, 15.5, 34.1 and 75.0 µg test item/L (equivalent Pd concentrations were 1.11, 2.43, 5.35, 11.8 and 25.9 µg Pd/L).

The concentrations of dissolved palladium in the aqueous phase were assessed by chemical analysis in the test solutions at test start (0h, fresh), at media renewal after 48 hours (aged and fresh) and test end (96h, aged). Samples of fresh medium were taken from the test solution and control prior to distribution to the test vessel. Samples of aged test media were taken directly from the test vessel and control. Recovery rates in fresh test solutions were between 68.5 – 80.9 % of nominal concentrations. During the incubation period of 48 hours, the palladium concentrations decreased and showed concentrations between 39.0 – 62.9 % of nominal concentrations in aged samples.

The geometric mean of the measured test item concentration over the test period were between 56.2 and 70.7 % of nominal concentrations. In accordance with OECD 203 (2019) the effect assessment was based on the geometric mean measured concentrations of 0.683, 1.56, 3.60, 8.35 and 14.5 µg Pd/L, equivalent to 1.98, 4.52, 10.4, 24.2 and 42.1 µg test item/L.

At test end, no mortality was observed in the control. In addition, the dissolved oxygen concentration was at least 60% of the air saturation in the control and test vessels during the test. Therefore, the test was valid according to OECD 203.

 

The test item had a statistically significant effect in the immobilization of the daphnids in the two highest test concentrations of 8.35 and 14.5 µg Pd/L. The LC₅₀after the 96 hours exposure period was calculated to be 5.48 µg Pd/L, which is equivalent to 15.9 µg test item/L.

Description of key information

The 96-hour LC50 was determined to be 5.48 µg Pd/L. 

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

15.9 µg/L

Additional information

A study was performed to determine the acute toxicity of Palladium (II) di(4-oxopent-2-en-2-oate) (CAS 14024-61-4) to zebrafish (Danio rerio). The study was performed according to the OECD guideline 203 and the EEC method C.1. The fish were exposed to five test concentrations of the test item under semi-static conditions for a period of 96 hours. The geometric mean measured concentrations were 0.683, 1.56, 3.60, 8.35 and 14.5 µg Pd/L, equivalent to 1.98, 4.52, 10.4, 24.2 and 42.1 µg test item/L. The LC₅₀after the 96 hours exposure period was calculated to be 5.48 µg Pd/L, which is equivalent to 15.9 µg test item/L.