Hydrogen bis[2,4-dihydro-4-[(2-hydroxy-5-nitrophenyl)azo]-5-methyl-2-phenyl-3H-pyrazol-3-onato(2-)]chromate(1-)

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

other: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

From June 3 to July 31, 2014

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The complete read across justification is detailed in section 13. Source study has reliability 1.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

After sampling, the test medium samples (0.5 ml) were mixed with 0.5 ml methanol and stored deep-frozen (below -18 °C) until analysis.

Vehicle:

no

Details on test solutions:

The concentrations in the main test were spaced by a factor of 2.2. The necessary amount of test substance for preparing the stock solution was weighed on weighing scoops and transferred to a volumetric flask. Test medium was added up to the bench mark and the solution was homogenised by shaking. The lower test solutions were prepared by dilution of the stock solution. Defined volumes of the prepared solution were transferred to each test vessels. The test solution volume was 50 ml per test vessel.

Test organisms (species):

Daphnia magna

Details on test organisms:

- Test organism: Daphnia magna STRAUS, Clone V. The animals are continuously bred in the laboratory.
- Source: Umweltbundesamt in Berlin/Germany.
- Breeding: as single culture (one daphnid per 100 ml) in Elendt M4 medium.
- Feeding: single cell green algae (Desmodesmus subspicatus, former Scenedesmus subspicatus) at least three times a week.

The medium was changed three times per week. A pipette was used to separate the young daphnids from the adults. Freshly hatched daphnids max. 24 hours old were used for the test.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

13° dH (232 mg/l as CaCO3)

Test temperature:

20.1 - 21.3 °C

pH:

7.95 - 8.08

Dissolved oxygen:

>= 8.3 mg/l

Nominal and measured concentrations:

see table below

Details on test conditions:

Test procedure: static
Exposure to light: 16 hours photoperiod / 8 hours darkness daily
Test vessels: four 100 ml glass beakers per concentration, each filled with 50 ml
Loading: at least 10 ml of test solution for each animal
Aeration: none
Number of animals: 20 per concentration in 4 replicates of 5

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

45.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

93.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 86.3 - 101

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

9.39 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

24.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 15.9 - 36.6

Details on results:

After 24 hours of exposure no immobilisation above the allowed control immobilisation was observed in the control and up to 45.5 mg/l. 70 % of the daphnids were found immobile at 100 mg/l.
After 48 hours of exposure no immobilisation above the allowed control immobilisation was observed in the control and up to 9.39 mg/l. 20 % of the daphnids were immobilised at 20.7 mg/l. At the two highest test item concentrations of 45.5 and 100 mg/l all daphnids were found immobile.

Results with reference substance (positive control):

EC50 (24h) between 1.0 and 2.0 mg/l
Reference substance: potassium dichromate

Reported statistics and error estimates:

The 24 h and 48 h EC50 are the estimated concentrations where 50 % of the daphnids were immobilised after 24 and 48 hours, respectively.
For the evaluation of the 24 h and 48 h EC50, logit analysis using linear max. likelihood regression was used. The evaluation of data was performed by using ToxRat Professional 2.10.
The NOEC was established based on the highest concentration at which the immobilisation is not higher than the allowed control immobilisation (<= 10 % immobilisation).

Validity criteria fulfilled:

yes

Conclusions:

According to the results of the test, the EC50 (48 h) for immobilisation was determined to be 24.1 mg test item/l (nominal). The corresponding NOEC (48 h) was 9.39 mg test item/l (nominal).

Executive summary:

Method

Acute toxicity of substance to aquatic invertebrates was investigated in a 48 -hour study under static exposure conditions, 20/daphnia per concentrations divided in 4 replicates. Nominal concetrations were 1.94, 4.25, 9.39, 20.7, 45.5 and 100 mg/l.

Results

The initial measured content of test substance was 96 % of nominal, the arithmetic mean of fresh and aged samples was 95 % of nominal.

Since the mean measured concentration of the substance was between 80 – 120 %, the effect levels were evaluated using nominal concentrations of the test item.

ECx and NOEC values of daphnids exposed to the test item evaluated using nominal concentrations:

Endpoint	concentration [mg test item/l]
	24 h	48 h
NOEC	45.5	9.39
EC50	93.3	24.1
95 % confidence limit of EC50	86.3 - 101	15.9 – 36.6

Description of key information

EC50 (48h) = 24.1 mg/l

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

24.1 mg/L

Additional information

No experimental studies were available on Solvent Orange 062, thus the assessment relied on a read across approach. Solvent Orange 062 and Similar Substance 01 are chromium complexes with 2 ligands. In both cases, the 2 ligands have the same chemical structure, i.e. a phenyl ring connected via diazo bond to a phenyl pyrazole. These ligands show minor differences in the position of substituents, i.e. hydroxy and nitro gorups, as well as in the presence of a sulfonate group in Similar Substance 01.

All information about the read across process is inserted in section 13.

In the available study on Similar Substance 01 (purity > 80 %), 20 daphnia per concentrations divided in 4 replicates were exposed to test substance under static exposure conditions. Nominal tested concentrations were 1.94, 4.25, 9.39, 20.7, 45.5 and 100 mg/l and there was evidence that the concentration of test substance was satisfactorily maintained throughout the test. The EC50 (48 h) for immobilisation was determined to be 24.1 mg/l and the corresponding NOEC (48 h) was 9.39 mg/l. The test was conducted according to OECD guideline 202.