Dipotassium hexacyanocobalt(II)-ferrate(II)

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

8.12.2014-20.2.2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was performed according to the recommended Guidelines (OECD Guidelines for Testing of Chemicals (April 2004) No 202 "Daphnia sp., Acute Immobilisation Test" and Method C.2 of Commission Regulation (EC) No. 440/2008) and GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

April 2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

(EC) No. 440/2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Certificate is included in the study report.

Analytical monitoring:

yes

Details on sampling:

- Concentrations: dissolved test item concentration: 1.9 mg/L
- Sample storage conditions before analysis: The samples were stored frozen prior to analysis.

Vehicle:

no

Details on test solutions:

See Any other information on materials and methods for more information.

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Adding test item (1100 mg) to test water (11 L). Stirring solution for 48 h with propeller (1500 rpm). Filtration through a 0.2 μm Sartorius Sartopore filter (approximately 1 liter discarded in order to pre-condition the filter)
- Evidence of undissolved material (e.g. precipitate, surface film, etc): Substance difficultly dissolved in water.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- strain: 1st instar
- Source: In-house laboratory cultures.
- Age at study initiation (mean and range, SD): Less than 24 hours old
- Feeding during test: No feeding during test

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Post exposure observation period:

No post exposure observation period.

Hardness:

250 mg/L as CaCO3

Test temperature:

21 °C

pH:

pH of 7.8 ± 0.2

Dissolved oxygen:

Dissolved oxygen concentrations were recorded at the start and termination of the test. Dissolved oxygen concentration were measured using a Hach Flexi handheld meter.
Control: 0 hours: 9.2 mg O2/L; 48 hours: 8.7 mg O2/L
Test solution: 0 hours: 9.0mg O2/L; 48 hours: 8.7 mg O2/L

Nominal and measured concentrations:

Measured cobalt concentration of 0.32 mg/L; equivalent to dissolved test item concentration of 1.9 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL glass jars
- Type: covered
- Material, size, headspace, fill volume: Glass jars, 250 ml. 200 ml test preparation
- Aeration: Test preparation was aerated before test started. No aeration during test.
- Renewal rate of test solution (frequency/flow rate): No renewal
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): Four
- No. of vessels per control (replicates): Four

TEST MEDIUM / WATER PARAMETERS (see Any other information on method and materials for more information)
- Source/preparation of dilution water: Reconstituted water (ISO medium). Test item was dissolved directly into the test medium.
- Culture medium different from test medium: Elendt M7 medium
- Intervals of water quality measurement: Water temperature was recorded daily throughout the test. Dissolved oxygen concentrations and pH were recorded at the start and termination of the test.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours of light and 8 hours of darkness with 20 minute dawn and dusk transition periods
- Light intensity: 480 to 511 lux

TEST CONCENTRATIONS
- Justification for using less concentrations than requested by guideline: The main test was performed with 1 test concentration. Preliminary solubility work conducted indicated that the test item was practically insoluble in water using traditional methods of preparation e.g. ultrasonication. Based on this information the test item was categorized as being a ‘difficult substance’ as defined by the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures (OECD 2000). Therefore a media preparation trial was conducted in order to determine the solubility of the test item under test conditions. Due to the low solubility of the substance, it was anticipated that the toxicity response in the daphnias would be low. Therefore only four test concentration were used for the range-finding test.
- Range finding study: with the following test concentrations
- Test concentrations: 0.10, 1.0, 10 and 100% v/v saturated solution.
- Results used to determine the conditions for the definitive study: No significant immobilization was observed at the test concentrations of 0.10, 1.0, 10 and 100% v/v saturated solution. Based on this information, a single test concentration of four replicates, of 100% v/v saturated solution was selected for the definitive test.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate. The positive control was conducted between 21 July 2014 and 23 July 2014.

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 1.9 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1.9 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 other: % v/v saturated solution

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: no immobilization
- Abnormal responses: No abnormal responses
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No observations

Results with reference substance (positive control):

- Results with reference substance valid. Yes
- EC50/LC50: EC50: 24 hours: 1 mg/L and 48 hours: 0.58 mg/L
- Other:
NOEC: 24 hours: 0.56 mg/L and 48 hours: 0.32 mg/L
LOEC: 24 hours: 1.0 mg/L and 48 hours: 0.56 mg/L

Reported statistics and error estimates:

An estimate of the EC50 values was given by inspection of the immobilization data.

Table 1. Cumulative Immobilization Data in the Definitive Test

Nominal Concentration (% v/v Saturated Solution)		Cumulative Immobilized Daphnia (Initial Population: 5 Per Replicate)
		24 Hours			48 Hours
		No. Per Replicate	Total	%	No. Per Replicate	Total	%
Control	R1	0	0	0	0	0	0
	R2	0			0
	R3	0			0
	R4	0			0
100	R1	0	0	0	0	0	0
	R2	0			0
	R3	0			0
	R4	0			0

Table 2. Water Quality Measurements

Nominal Concentration (% v/v Saturated Solution)		0 hours			24 hours	48 hours
		pH	mg O2/L	T °C	T °C	pH	mg O2/L	T °C
Control	R1	8	9.2	21	21	7.7	8.7	21
100	R1	8.2	9	21	21	7.8	8.7	21

Validity criteria fulfilled:

yes

Remarks:

Validity criteria as in OECD

Conclusions:

The acute toxicity of the test item to the freshwater invertebrate Daphnia magna has been investigated and gave a 48-Hour EC50 value of greater than 100% v/v saturated solution. EC50 values based on the 0-Hour measured test concentration were greater than 1.9 mg/L. The No Observed Effect Concentration was 1.9 mg/L. This study showed that there were no toxic effects at saturation.

Executive summary:

A study was performed to assess the acute toxicity of the test item to Daphnia magna. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (April 2004) No 202, "Daphnia sp., Acute Immobilisation Test" referenced as Method C.2 of Commission Regulation (EC) No. 440/2008.

Preliminary solubility work conducted indicated that it was not possible to obtain a testable solution of the test item using traditional methods of preparation e.g. ultrasonication.

Following a preliminary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test item at a nominal concentration of 100% v/v saturated solution for 48 hours at a temperature of 21 °C under static test conditions.

Analysis of the test preparations was performed for the concentration of cobalt present. The equivalent test item concentrations were then determined based on the cobalt content of test item.

Exposure of Daphnia magna to the test item gave EC50 values based on the 0-Hour measured test concentration of greater than 1.9 mg/L. The No Observed Effect Concentration was 1.9 mg/L.

This study showed that there were no toxic effects at saturation.

Description of key information

Static 48-hour test for freshwater invertebrate Daphnia manga: EC50 > 1.9 mg/L, NOEC = 1.9 mg/L(OECD 202, EU Method C.2, GLP)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1.9 mg/L

Additional information

The acute toxicity of the test item to the freshwater invertebrate Daphnia magna has been investigated and gave a 48-Hour EC50 value of greater than 100% v/v saturated solution. EC50 values based on the 0-Hour measured test concentration were greater than 1.9 mg/L. The No Observed Effect Concentration was 1.9 mg/L. This study showed that there were no toxic effects at saturation.

However, based on the water solubility test the substance is highly insoluble in water, and can be regarded as a poorly soluble substance. Nevertheless, long-term aquatic studies are not considered necessary due to exposure considerations. Aquatic toxicity is unlikely to occur as the substance is manufactured and used only in closed, controlled environments, where water that might contain the substance in detectable amounts is pretreated before release into further treatment or the sewage system. As such, there is no emission to water. As no emissions of the substance to water are expected, the long-term toxicity testing on aquatic invertebrates is waived. The substance is also unreactive. Therefore, there are no data gaps in aquatic toxicity.