Pentyl 2-cyano-(3-(6-methoxybenzothiazol-2-ylimino)-2,3-dihydro-1H-isoindol-1-ylidene)acetate

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

Study period:

From Dec. 05, 2000 to Jan. 04, 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes

Analytical monitoring:

no

Remarks:

Considering the low aqueous solubility of the test substance (<1 mg/L), the test item concentration in medium was not verified analytically.

Details on sampling:

Not applicable

Vehicle:

yes

Details on test solutions:

No data

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: No data
- Source (laboratory, culture collection): Non-axenic strain of the test species obtained from 'The Collection of Algal Cultures' of the Institute of Plant
Physiology at the University of Goettingen (Germany)
- Method of cultivation: Exponentially-growing stock cultures are maintained in the test facility under constant temperature conditions

ACCLIMATION
- Culturing media and conditions (same as test or not): No
- Any deformed or abnormal cells observed: No

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

No

Hardness:

No data

Test temperature:

21-25 °C

pH:

7.4-10.3

Dissolved oxygen:

No data

Salinity:

No data

Nominal and measured concentrations:

0, and 1 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Renewal rate of test solution (frequency/flow rate): No
- Initial cells density: 10E+4 cells per mL in the test medium.

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- The algal inocula for a test are taken from an exponentially-growing pre-culture and are mixed with the nutrient medium

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: yes
- Light intensity and quality: 60-120 µE × m-2 × S-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Mean cell density, Percentage inhibition of cell growth and growth rate

- Range finding study
- Test concentrations: 0, and 1 mg/L (nominal)

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): No abnormalities
- Effect concentrations exceeding solubility of substance in test medium: Test conducted at maximum water solubility.
No toxic effects were observed against algae at 1 mg/L (nominal).

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

No data

Table 1. Results

	Concentration Nominal ( mg/L)	Area under growth curve	Inhibition (+) / Increase H(-) [%]
Mean growth (b) [integral of biomass]	0	611389	0.0
	1	607778	0.6
	Concentration Nominal ( mg/L)	Growth rate	Inhibition (+) / Increase H (-) [%]
Mean growth rate (r)	0	1.46	0.0
	1	1.46	0.3

Validity criteria fulfilled:

yes

Conclusions:

Under the test conditions employed, the 72 h EbC50, ErC50 and NOEC of the test substance were determined to be > 1 mg/L.

Executive summary:

A study was performed to assess the adverse effects of the test substance on growth and growth rate of the planktonic freshwater algal species Scenedesmus subspicatus CHODAT over several generations. The study was conducted in accordance with EU method C.3 and OECD guideline 201 in compliance with GLP.

Exponentially growing algal cells were exposed for a period of 72 h to a limit test concentration of nominally 1 mg/L.

The test was conducted using dissolved test material at maximum water solubility. Auxiliaries used to prepare the test media, i.e. for maximisation of the dissolved fraction, and removal of undissolved material, were an ultrasonic bath, a magnetic stirrer and folded filter.

The cell densities were measured at 24 h intervals. Inhibition of the algal population was measured as reduction in growth (index b) and growth rate (index r), relative to the control.

No toxic effects against algae were observed at the limit test concentration of 1 mg/L (nominal).

Considering the low aqueous solubility of the test substance (< 1 mg/L) no specific analysis was established.

Under the employed test conditions, the 72 h E_bC₅₀, E_rC₅₀ and NOEC of the test substance were determined to be > 1 mg/L.

Description of key information

There is no adverse effects whatsoever of the test substance on algal biomass increase or growth rate at a nominal concentration of 1 mg/L, which resulted in the maximum attainable aqueous concentration (solubility limit). The NOEC of the test substance is therefore determined to be ≥ 1 mg/L. The 72 h EbC50 and ErC50 could not be determined but are hypothetically > 1 mg/L.

Additional information

A study was performed to assess the adverse effects of the test substance on growth and growth rate of the planktonic freshwater algal species Scenedesmus subspicatus CHODAT over several generations. The study was conducted in accordance with EU method C.3 and OECD guideline 201 in compliance with GLP.

Exponentially growing algal cells were exposed for a period of 72 h to a limit test concentration of nominally 1 mg/L.

The test was conducted using dissolved test material at maximum water solubility. Auxiliaries used to prepare the test media, i.e. for maximisation of the dissolved fraction, and removal of undissolved material, were an ultrasonic bath, a magnetic stirrer and folded filter.

The cell densities were measured at 24 h intervals. Inhibition of the algal population was measured as reduction in growth (index b) and growth rate (index r), relative to the control.

No toxic effects against algae were observed at the limit test concentration of 1 mg/L (nominal).

Considering the low aqueous solubility of the test substance (< 1 mg/L) no specific analysis was established.

Under the employed test conditions, the 72 h E_bC₅₀, E_rC₅₀and NOEC of the test substance were determined to be > 1 mg/L.

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