Trisodium bis[4-[4,5-dihydro-4-[(2-hydroxy-5-nitrophenyl)azo]-3-methyl-5-oxo-1H-pyrazol-1-yl]benzene-1-sulphonato(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:

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

Adequacy of study:

key study

Study period:

From June 11th to October 31st, 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Details on the read-across are available in section 13.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Qualifier:

according to guideline

Guideline:

other: EPA 540/9-85-005

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The samples were stored deep-frozen until the analyses were performed.

Vehicle:

yes

Details on test solutions:

The test medium used was reconstituted water prepared according to the EEC Directive.
Its composition was:
CaCl2 × 2H2O 294 mg/l
MgSO4 × 7H2O 123 mg/l
NaHCO3 65 mg/l
KCl 5.8 mg/l.
Bidistilled water was used to prepare the test medium.

Test organisms (species):

Daphnia magna

Details on test organisms:

Breeding: in the laboratories of RCC under standardized conditions.
Age: less than 24 hours

Test type:

static

Water media type:

freshwater

Total exposure duration:

48 h

Remarks on exposure duration:

visual assessment of the mobility of the daphnids after 24 and 48 hours

Test temperature:

20.5 °C

pH:

At the beginning and end of the respective experiments:
start: 8.2
end: 8.3

Dissolved oxygen:

At the beginning and end of the respective experiments:
start: 9.1 mg/l
end: 9.3 mg/l

Nominal and measured concentrations:

The substance was dissolved in the test medium at a concentration of 100 mg/100 ml (stock solution).
Based on pre-test results (k), series o sequential dilutions with the test medium were prepared to obtain the final test concentrations of the test article which were in the range 6.25 to 100 mg/l.
Untreated control samples were also tested.

Details on test conditions:

The daphnids were exposed to the test article in 50 ml beakers containing 20 ml test medium with 10 daphnids per beaker.
Illumination: 16 hours

Reference substance (positive control):

yes

Remarks:

a separate test with the reference compound potassium dichromate was carried out on September 20, 1989 (run with RCC Project 247050).

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

29.3 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

63.7 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

126 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

The values or EC0 after (29.3 mg/l), EC50 (63.7 mg/l) and EC100 after 48 hours (126 mg/l) were calculated by linear regression.
When the EC50 was calculated by the Logit-model, values of EC50 after 48 hours of 63.7 mg/l were obtained with the following confidence limits:
90 % confidence limit (48 hours): 55.2-75.8 mg/l
95 % confidence limit (48 hours): 53.7-79.1 mg/l
99 % confidence limit (48 hours): 50.7-87.5 mg/l

The dose response curve was round to be:
Logit (48 hours) = -19.91 + 4.793 × log (dose).
The 95 %-confidence limits ror the slopes were:
48 hours : 3.176-6.409

Results with reference substance (positive control):

The values of EC0 after 24 and 48 hours (1.42 mg/l and 0.965 mg/l), EC50 after 24 and 48 hours (2.788 mg/l and 1.307 mg/l) and EC100 after 24 and 48 hours mg/l and 1.770 mg/l) were determined by linear regression.
When the EC50 was calculated by the Logit model, values of EC50 after 24 and 48 hours of 2.25 mg/l and 1.32 mg/l were obtained with the following confidence limits:
95 % confidence limit (24 hours): 1.938 - 10.82 mg/l
95 % confidence limit (48 hours): 1.203 - 1.426 mg/l
The dose response line was found to be:
Logit (24 hours) = -3.068 + 3.781 × log (dose)
Logit (48 hours) = -2.516 + 8.999 × log (dose).
The 95 %-confidence limits for the slopes were:
24 hours : -1.98, 9.542
48 hours : 3.181, 14.82

Reported statistics and error estimates:

The EC50 was estimated for 48 hours of exposure by using the Logit model. EC0, EC50 and EC100 values were calculated by linear regression of values used for logit estimation if possible.

Validity criteria fulfilled:

yes

Conclusions:

EC50 (48h): 63.7 mg/l

Executive summary:

Materials and methods

The substance was tested for its acute toxicity to Daphnia magna, according to OECD guideline 202.

At 48 hours of exposure the Logit model was used to assess EC50. The tests were validated by testing potassium dichromate.

Observation

The immobilization observed with the control animals was 0 % after 48 hours.

The EC50 values determined for potassium dichromate after 24 and 48 hours were 2.25 and 1.32 mg/l, respectively.

Results

EC0 (48h) = 29.3 mg/l

EC50 (48h) = 63.7 mg/l

EC100 (48h) = 126 mg/l

The substance showed slight toxicity to daphnids when exposed for 48 hours.

Description of key information

EC50 (48 h) = 63.7 mg/l

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

63.7 mg/L

Additional information

No data on Acid Brown 303 was available. Therefore, available data on a structural analogue, i.e Similar Sustance 01, was used to assess the short-term toxicity to aquatic invertebrates. Details on the read-across approach are available in section 13.

Similar Substance 01 was tested according to OECD guideline 202.

The EC50 value was estimated to be >100 mg/l for 24 hours exposure.

At 48 hours of exposure the Logit model was used to assess EC50. The result was a value of 63.7 mg/l.