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

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

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 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

The test item concentration in the test solution was measured at the start and end of exposure. At the start, the solution sampled from the container for preparation was used for the measurement. At the end of exposure, equal volume of the test solution was taken out from test vessels in each exposure level, mixed, and used for the measurement.

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: The test sample was added in medium to produce the nominal loading concentrations of 10 and 1 mg/L. After that, they were stirred for 24 and 48 hours under 23±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 (n=2).
The result suggested !hat the solubility of the test item in medium ranged from 0.6 to 1 mg/L. lt is only necessary to select nominal concentration which is higher than the predicted value of solubility. Therfore, a nominal loading rate of 2 mg/L was used for the actual test:
Correction with the purity was not applied to the preparatiou of the test solution.
Dispersed suspension of tbe test item (nominal loading concentration: 2 mg/L) was produced by stirring for about 48 hours, and then filtered to prepare the filtrate. Five test concentrations of 100, 55.6, 30.9, 17.1 and 9.53% as filtrate content (a geometric series with a factor of 1.8) and a control were selected.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Strain: ATCC 22662
- Source (laboratory, culture collection): Originally from the American Type Culture Collection (12301 Parklawn Drive Rockville, Maryland 20852-1776 U.S.A.) on June 30, 1995 and have been cultured in the Kururne Labaratory
- Age of inoculum (at test initiation): The pre-culture, incubated under the same conditions as the test for 3 days and exponentially growing was used as inoculum to prepare the initial cell concentration of approximately 104 cells/mL.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21 - 24 °C

pH:

7.8 - 8

Nominal and measured concentrations:

- Nominal: 2 mg/L ( = 100 %); 55.6%, 30.9%, 17.1%, 8.53%
- Measured: 0.941, 0.531, 0.294, 0.177, 0.0982 mg/L; concentrations were based on a range-finding study

Details on test conditions:

TEST SYSTEM
- Test vessel: sterilized 500 mL Erlenmeyer flask (with gas-permeable Silicosen®)
- Volume of test solution: 600 mL/controllevel (100 mL/vessel); 300 mL/exposure Ievel (100 mL/vessel)
- Initial cells density: the pre-culture, incubated under the same conditions as the lest for 3 days and exponentially growing was used as inoculum to prepare the initial cell concentration of approximately 10E4 cells/mL.
- No. of vessels per concentration: 3
- No. of vessels per control: 6

GROWTH MEDIUM
- Standard medium used: yes (medium recommended in OECD test guideline 201)

TEST MEDIUM / WATER PARAMETERS
- Intervals of water quality measurement: the pH of the test solution was measured at the start and end of exposure. For the measurement of pH, another solution sampled from the container for preparation was used at the start of exposure and one vessel in each test level was used for the measurement at the end of exposure. The temperature and light intensity in the incubator were measured once a day during exposure.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: No
- Light intensity and quality: Continuous illumination provided with 60 - 120 µE·mE-2·sE-1 at the level of the test solutions, not varied more than 20% using a fluorescent light with wavelength range of 400 - 700 nm.


EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: Cell concentration was counted with particle counter (Model COULTER Z1, Beckman Coulter) at 24, 48 and 72 hours after the start of exposure

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8
- Range finding study: In the preliminary studies, excessive amount of the test sample was added in medium (nominal loading concentration: 2 mg/L) and stirred for about 48 hours. After that, insoluble material was removed to produce the saturated solution which was at around the predicted solubility (1 mg/L). Then, the test organisms were · exposed to the saturated solution. As a result, the growth inhibition below 50% was observed in the saturated solution. In addition, no growth inhibition was observed in the 9.53% content solution of the saturated solution. Therefore, five test concentrations described above were selected.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.941 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

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

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.941 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.941 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.531 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

No acute toxic effects within the range of solubility.

Results with reference substance (positive control):

An algae growth inhibition test of potassium dichromate (Reagent grade, Wako Pure Chemical Industries) with the test organisms was conducted to confirm the reproducibility of the test system (August 29 - September 1, 2005). The EbC50 (0 - 72h) and ErC50 (0 - 3d) of potassium dichromate were 0.492 and 1.09 mg/L respectively [Background data : Mean ± S.D. of EbC50 ( 0-72h ) and ErC50 (0 - 3d) was 0.408 ± 0.079 mg/L and 1.12 ± 0.44 mg/L (n=10), respectively (including extrapolated value of ErC50s (0 - 3d)].

Validity criteria fulfilled:

yes

Conclusions:

With high probability acutely not harmful to aquatic algae.

Description of key information

With high probability acutely not harmful to aquatic algae.

Additional information

A study according to GLP and OECD 201 was conducted to determine the effect of the test item on the growth of the aquatic algae Pseudokirchneriella subcapitata (Kurume Laboratory 2005). After 72 h no effects were observed up to the limit of water solubility (at a nominal loading rate of 2 mg/L).