Trisodium bis[2-hydroxy-5-nitro-3-[[2-oxo-1-[(phenylamino)carbonyl]propyl]azo]benzenesulphonato(3-)]cobaltate(3-)

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

For the determination of the test concentrations with HPLC, the stock solution of the standards was not prepared using test medium:methanol (8:2; v:v) containing 10 mM ammonium acetate as given in the study plan but with water:acetonitrile (1:1; v:v). This deviation has no influence on the outcome of the test because the test item was completely soluble in the solvent used (water:acetonitrile (1:1; v:v)). After 48 h of exposure at the lowest concentration (1.19 mg/l), a higher immobilization rate (30%) than at the next two higher concentrations was observed (17.5 and 27.5%). Since this observation was obviously an outlier, the calculation of the 48 h EC50 was conducted by excluding this lowest concentration. Consistently, the EC10 was not reported, since not reliably assessable; and the NOEC was declared as being lower than the 2nd lowest concentration (<2.62 mg/l instead of <1.19 mg/l).

Deviations:

yes

Remarks:

see remarks

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

yes

Remarks:

ultra-pure water:acetonitrile (1:1, v:v)

Details on test solutions:

To prepare the standard solutions, a stock solution (test item dissolved in ultra-pure water:acetonitrile (1:1, v:v)) was diluted with medium:methanol (8:2; v:v) containing 10 mM ammonium acetate.
Test samples were diluted to obtain a final sample composition of sample:methanol (8:2, v:v) containing 10 mM ammonium acetate before HPLC analysis.

Test organisms (species):

Daphnia magna

Details on test organisms:

Test organism: Daphnia magna (Straus, 1820), derived from a healthy stock and not first brood progeny
Breeding: Parental and young Daphnia held in 4 l glass aquaria (3 l medium) at 20±2 °C
Illumination:16 h per day
Medium Continuously aerated Elendt M4 medium ; prepared with ultra-pure water (conductivity <1.5 µS/cm)1
Feed: Suspension of Desmodesmus subspicatus in Elendt M4 medium with an optical density OD680 of about 15 units Control of sensitivity
Acute reference test with potassium dichromate conducted twice a year.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test temperature:

18–22 °C, controlled at ±1 °C

pH:

6 to 9. The pH should normally not vary by more than 1.5 units in one test.

Dissolved oxygen:

8.6 – 9.6 mg/L

Nominal and measured concentrations:

The test concentrations were 80.0, 36.4, 16.5, 7.51, 3.42 and 1.55 mg/l nominal concentration corresponding to 61.4, 27.9, 12.7, 5.76, 2.62 and 1.19 mg/l active ingredient.
Prior to the definitive test a non-GLP range finding test with nominal concentrations of 0.1, 1, 10 and 100 mg/l of Acid Yellow 194, corresponding to 0.077, 0.77, 7.67 and 76.7 mg/l of active ingredient, was performed.

Details on test conditions:

Test vessel: 100 ml beakers, all-glass, with 50 ml of test medium, covered with a glass plate to avoid evaporation and contamination of the test solutions with dust
Test medium: Elendt M4 medium prepared with ultra-pure water (conductivity <1.5 µS/cm)
Number of Daphnia: 40 individuals per test concentration, 20 per vessel

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

ca. 2.62 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Concentration analytically verified

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

ca. 7.63 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Concentration analytically verified

Details on results:

After 48 h, the following immobilization rates were observed: 100% at 61.4 mg/l, 82.5% at 27.9 mg/l, 50% at 12.7 mg/l, 27.5% at 5.76 mg/l and 17.5% at 2.62 mg/l. At 1.19 mg/l, an immobilization rate of 30%, i.e. higher than at the next two higher concentrations, was observed. Since this observation was obviously an outlier, the calculation of the 48 h EC50 was conducted by excluding the lower concentration.
The no observed effect concentration (NOEC) after 24h was determined to be <2.62 mg/l, since the 1.19 mg/l concentration cannot be reliably considered.
No significant effects (≤10% immobilization) were observed in the blank controls.
Based on these effects and the nominal concentrations of the active ingredient, the 48h-EC50 of Acid Yellow 194 to Daphnia magna was calculated to be 9.83 mg/l (95% confidence limits: 7.74– 12.3 mg/l). When considering the lowest concentration, this value would be 7.63 mg/l, with confidence limits ranging from 1.18 to 38.0 mg/l.

Validity criteria fulfilled:

yes

Conclusions:

NOEC < 2.62 mg/L at 48h
EC50 = 7.63 mg/L at 48h

Executive summary:

Toxicity to aquatic invertebrates was investigated following the OECD Guideline 202 (Daphnia Magna Acute Immobilisation Test).
Based on the test results, the tested substance showed some toxic effects on Daphnids and the EC50 (48 h) was set at 7.63 mg/l.

The tested substance should be considered as toxic for daphnids and shoul be classified as: Aq. Chronic 2, H411.

Description of key information

Toxicity to aquatic invertebrates was investigated following the OECD Guideline 202 (Daphnia Magna Acute Immobilisation Test).
Based on the test results, the tested substance showed some toxic effects on Daphnids and the EC50 (48 h) was set at 7.63 mg/l.

The tested substance should be considered as toxic for daphnids and shoul be classified as: Aq. Chronic 2, H411.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

7.63 mg/L