Strontium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate

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)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Sampling method: the concentration of the test item in the test solution was measured at the start and end of exposure. At the start of exposure, the solution separately sampled was used for analysis. At the end of exposure, the equal volume of the test solution was taken out from the middle layer in four test vessels in each test Ievel and then mixed for analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
In a preliminary study the solubility in the test item was measured by using different loading concentrations: Measurement solution was prepared by addition of the test item. The addition was conducted by two methods. In method 1, the test sample was added to dilution water (dechlorinated tap water) to produce the concentrations of 10 and 1 mg/L.
In method 2, the test sample dissolved in DMSO was added to an Erlenmeyer flask and dried out by nitrogen gas while coating inner wall of the flask. And then, the dilution water (dechlorinated tap water) was added to produce the concentrations of 0.100 and 0.0100 mg/L. After addition of method 1 and 2, they were stirred for 24 and 48 hours under 24±1 °C and settled, and then the middle layer was collected. The middle layer was filtered through a glass fiber filter (No absorption to the filter was checked.) (GB-140, pore size: 0.4 µm) and centrifuged (10,000xg, 30 min) to remove the insoluble material. Then, the concentration of the test item was measured by HPLC. The result suggested that the solubility of the test item in dilution water ranged from 0.100 to 1.00 mg/L. It is only necessary to select nominal loading concentration which is higher than the predicted value of solubility; however, there was variability in the results at 10.0 mg/L. Therefore, a nominal loading rate of 1 mg/L was used for the actual test:
Correction with the purity was not applied to the preparation of the test solution. About 1 mg of test sample and 1000 mL of dilution water were mixed aud stirred with a magnetic stirring bar for about 48 hours, and then settled for about one hour under 20 ± 1 °C. After that the middle layer was collected and filtered with a glass fiber filter (GB-140, pore size: 0.4 µm, ADVANTEC). The filtrate as the test solution was divided into each test vessel.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Strain: Clone A
- Source: young daphnids produced by parents which were cultured in the Kurume Labaratory were used. Daphnids originally came from the University of Sheffield (Address: Sheffield S10 2UQ, United Kingdom).
- Age at study initiation: less than 24-hour old daphnids
- Method of breeding: the parents to obtain young daphnids were bred in the same quality of water (dechlorinated tap water), water temperature (20 ± 1 °C), and photoperiod (16-hour light/8-hour dark) as used in the test. Parent daphnids used for the test were same Iot, and their age and survival rate were 15-day old and 100%. Chlorella vulgaris of 0.1 to 0.2 mgC/day per daphnia was fed to the parents once a day.
- Feeding during test: No

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

29.2 mg/L (as CaCO3)

Test temperature:

20 ± 1°C

pH:

7.9 - 7.8

Dissolved oxygen:

8.8 - 8.6 mg/L

Nominal and measured concentrations:

- Nominal: 1 mg/L
- Measured: 0.772 mg/L (geometric mean); this concentration was based on a previous study.

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL glass beaker
- Type: closed (the test vessels were covered with lid in order to prevent dust, and volatilization of the test solution)
- No. of organisms per vessel: 5
- No. of vessels per concentration: 4
- No. of vessels per control: 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dechlorinated tap water, aerated sufficiently

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16-hour light/8-hour dark photoperiod daily with room lamp

EFFECT PARAMETERS MEASURED:
lmmobility and symptom were observed at 24 and 48 hours after exposure. Daphnids were considered immobile if they were not able to swim within 15 seconds after gentle agitation of the test vessel.

TEST CONCENTRATIONS
- Justification for using less concentrations than requested by guideline: in the results of the preliminary studies, excessive amount of the test sample was added to dilution water (nominal loading concentration: 1 mg/L) and they were stirred for about 48 hours. Then saturated solution (predicted solubility in dilution water was around 0.5 mg/L for both saturated solutions) was prepared by removal of insoluble material and the test organisms were exposed to the solution. The results in the preliminary studies suggest that the saturated solution affects no immobility. Therefore, a limit test with this concentration was conducted.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 0.772 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: no effects observed up to the limit of water solubility

Details on results:

No acute toxic effects within the range of solubility.

Results with reference substance (positive control):

A 48-hour acute immobilization test of potassium dichromate (Reagent grade, Wako Pure Chemical Industries) with the test organisms was conducted (August 8-10, 2005) to confirm the reproducibility of the test conditions. The 48-hour EC50 of the reference substance was 0.283 mg/L. This value was within the normal range of the reference substance in Kururne Labaratory (mean ± S.D.: 0.113-0.351 mg/L) [mean ± S.D.: 0.232± 0.059 mg/L (n=50)].

Validity criteria fulfilled:

yes

Conclusions:

With high probability acutely not toxic to aquatic invertebrates.

Description of key information

With high probability acutely not toxic to aquatic invertebrates.

Additional information

A static acute limit test according to GLP and OECD 202 was conducted to determine the toxicity of the test item to Daphnia magna (Kurume Laboratory, 2005). Daphnids (Daphnia magna, 20 per concentration) were exposed to a nominal loading rate of 1mg/L. Immobility was determined after 24 and 48 hours exposure. At test termination no effects were observed up to the limit of water solubility (at a nominal loading rate of 1 mg/L).