1,3-diethenyl-1,1,3,3- tetramethyldisiloxane and its platinum(0) complexes

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is highly insoluble in water, hence indicating that aquatic toxicity is unlikely to occur

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Remarks:

Non-GLP rangefinder study

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Version / remarks:

Rangefinder only

Principles of method if other than guideline:

Rangefinder for acute fish study

GLP compliance:

no

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Samples were taken from all test concentrations (0.1, 1 and 10 mg/L)
- Sampling method: Samples were taken at test start, 48 hours (fresh and aged solutions) and at 96 hours
- Sample storage conditions before analysis: Samples for Pt analysis were acidified with HNO3 and stored at 4°C until analysis. Samples were analysed immediately for the organic ligand.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution was prepared by weighing an adequate amount of the test item, transferring it to dilution water and stirring it for approximately 1 hour at room temperature at 700 rpm. The stock solution was filtered through a 0.2 µm PES filter in order to remove any insoluble material before application in the test. The stock solution was adequately diluted in dilution water in order to reach the final test concentrations.
- Solvent: No solvent used
- Controls: Dilution water

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: Zebrafish
- Source: Test facility bred
- Length at study initiation (length definition, mean, range and SD): 2.0 ± 1 cm

ACCLIMATION
- Acclimation period: 12 days
- Acclimation conditions: Same as test
- Type and amount of food during acclimation: Fed ad libitum throughout the holding period with live brine shrimp (Artemia salina)

FEEDING DURING TEST
- Fish were not fed during the test or for 24 hours beforehand

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

1.1 mmol/L

Test temperature:

23.0 - 23.1°C

pH:

8.27 - 8.64

Dissolved oxygen:

95 - 100% oxygen saturation

Nominal and measured concentrations:

Nominal concentrations: 0.1, 1 and 10 mg/L
Platinum could only be detected at the highest test concentration, at 0.064 - 0.076 mg/L, all other test concentrations were Measured concentrations of the organic ligand were all < LOQ (0.0025 mg/L)

Details on test conditions:

TEST SYSTEM
- Test vessel: borosilicate glass beakers of 3.0 L, containing 2.0 L of test solution
- Aeration: Slightly aerated using glass capillaries
- Renewal rate of test solution: Test solutions renewed after 48 hours
- No. of organisms per vessel: 5 for treatments and control
- No. of vessels per concentration: 1
- No. of vessels per control: 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Purified tap water
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Photoperiod: 12 hours light: 12 hours dark

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10 (rangefinder)

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: No effects on mortality or behavioural abnormalities at any test concentration

Validity criteria fulfilled:

not applicable

Conclusions:

At the highest test concentration of 10 mg L-1, no mortality was observed.

Executive summary:

Eilebrecht (2016) is a non-GLP rangefinder study with Danio rerio. A 96-hour semi-static study was conducted with test solution renewal afrer 48 hours. Analytical verification of both platinum and the organic ligand showed that none of the organic ligand could be detected (LOQ: 0.0025 mg/L) and very small amounts of platinum were detected in solution. At the highest test concentration of 10 mg L-1, no mortality or behavioural abnormalities were observed. As the test item was shown to be very poorly soluble in the rangefinder, and it was not possible to get higher amounts of test item into solution following further solubility trials, and no effects were observed at the highest nominal concentration tested, a definitive test was not conducted.

Description of key information

A range-finder study showed no toxicity at nominal concentrations up to 10 mg L^-1(highest concentration tested). Analytical monitoring of both the organic ligand and platinum showed very low concentrations of platinum and none of the organic ligand could be detected in solution. As the test item is very poorly soluble and it was not possible to get more of the test item into solution, aquatic toxicity is not expected at the limit of solubility and this was demonstrated in the range-finding study.

Additional information

A rangefinder study showed no toxicity at nominal concentrations up to 10 mg L^-1(highest concentration tested). Analytical monitoring of both the organic ligand and platinum showed very low concentrations of platinum and none of the organic ligand could be detected in solution. As the test item is very poorly soluble and it was not possible to get more of the test item into solution, aquatic toxicity is not expected at the limit of solubility and this was demonstrated in the range-finding study.

 

Karstedt concentrate was tested in range-finder studies with fish, Daphnia and algae (Eilebrecht 2016, Simon 2016, Wenzel 2016). The highest nominal test concentration used in the range-finders was 10 mg L^-1. The highest concentration test solutions were prepared by adding the test item to test media (20 mg in 2 litres), stirring for one hour and then passing the resulting ‘solution’ through a 0.2 µm PES filter. The filtrate was used directly as the highest test concentration (nominally 10 mg L^-1), while the lower test concentrations were prepared by appropriate dilution of the filtrate. This procedure ensured that only soluble components of the test item were assessed for toxicity. The resulting test solution at the highest concentration used in the range-finder is considered to be at the limit of solubility for the substance. Analytical monitoring of the test solutions was conducted, with both the organic ligand and platinum measured. In the range-finding studies, only very low concentrations of platinum were detected and the organic ligand was present close to or below the LOQ in all samples. No toxicity was observed for fish, Daphnia or algae.

 

As the substance was shown to be poorly soluble in test media and therefore only small amounts of platinum could be detected in the range-finder studies, further solubility trials were conducted in order to determine if it is possible to increase the concentrations of the test item components in solution. Although higher solubility was determined for the test item in a water solubility study, the water solubility result was based on analysis of platinum only, and similar levels of solubility were not observed with ecotoxicity test media. 96-hour solubility trials were conducted using the same media used in the fish andDaphniastudies, adjusted to pH 6, and with three different separation techniques trialled (decanting, filtering and centrifugation). An initial concentration of 4.3 mg L^-1Karstedt concentrate was used. The test solutions were analysed after 0, 24, 48, 72 and 96 hours. The organic ligand was present close to or below the LOQ in all samples (LOQ 2.16 µg L^-1), suggesting it is highly insoluble and therefore unlikely to be toxic to aquatic organisms. Platinum was detected in the solutions but measured concentrations were low, ranging from 3.90 to 9.43 µg Pt L^-1over the course of the test for filtered and centrifuged solutions. Measured concentrations were higher for the decanted solutions (45.16 µg Pt L^-1at 0 hours to 7.03 µg Pt L^-1at 96 h), however it is believed that this is likely to be due to some of the undissolved test material being included during the decanting phase.

 

Based on the solubility trials, it was not possible to get the organic ligand into solution and only small amounts of platinum were in solution. The platinum concentrations in solution are unlikely to lead to aquatic toxicity. Comparing the measured concentrations of platinum from the filtered and centrifuged solutions against the acute environmental reference values (ERV) for other platinum substances (481 µg L^-1for dihydrogen hexahydroxyplatinate, 117 µg L^-1for dihydrogen hexahydroxyplatinate, compound with 2-aminoethanol, 108 µg L^-1for diammonium hexachloroplatinate, 7600 µg L^-1for tetraammineplatinum hydrogencarbonate, 9750 µg L^-1for platinum tetraamine diacetate and 20.5 µg L^-1for hexachloroplatinic acid) shows that measured platinum concentrations released from Karstedt concentrate are lower than the ERVs and therefore aquatic toxicity is not expected. The most toxic platinum substance, hexachloroplatinic acid, is expected to release platinum in the form of chloroplatinate anions and, although the exact form of platinum released from Karstedt concentrate is not known, it is not expected to be chloroplatinate. Any platinum released from Karstedt concentrate is therefore likely to be in a less toxic form than that released from hexachloroplatinic acid. However, even comparing the platinum release from the solubility trial against the acute ERV for hexachloroplatinic acid, as a worst case approach, aquatic toxicity from Karstedt concentrate is not expected.

 

Analysis of the organic ligand showed that it was present close to or below the LOQ in all samples, although the fate of the ligand is not clear. The ligand may be very poorly soluble and therefore removed during filtering of the solutions (it appears that solubility of Karstedt concentrate in test media is lower than solubility of the organic ligand alone), it may be strongly adsorbing to the test vessels or filters, although several different methods for preparing the test solutions have been trialled in order to reduce this possibility, or it may hydrolyse leading to breakdown products that are not detected in the analysis. If breakdown products are present these are not considered to contribute to the toxicity of the test item as the breakdown products would also have been present in the range-finder tests in which no toxicity was observed.

 

Based on the results from solubility trials it is concluded that neither the organic ligand nor the platinum component of Karstedt concentrate will enter solution in high enough amounts to lead to aquatic toxicity. This is supported by the results of the range-finder studies conducted with three trophic levels at a highest nominal concentration of 10 mg L^-1. As it is not possible to get more of the test item in solution, conducting definitive ecotoxicity studies is not considered to be necessary. To conclude on environmental classification, the standard approach would be to test up to a nominal concentration of 100 mg L^-1. However, for this substance testing at a nominal concentration of 100 mg L^-1is considered to be unnecessary, as the limit of solubility appears to have been reached at the nominal concentration of 10 mg L^-1, and testing at higher concentrations would not lead to additional test item in solution. As no toxicity was observed at the limit of solubility in the range-finder studies, neither an acute or chronic environmental classification is considered to be required for the substance.