1-ethyl-1,2-dihydro-6-hydroxy-4-methyl-5-[(2-nitrophenyl)azo]-2-oxonicotinonitrile

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 - 18 Jul 1997

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

information on number of replicates and results from positive control missing

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

425-310-7

EC Name:

-

Cas Number:

77889-90-8

Molecular formula:

C14H10ClN5O4

IUPAC Name:

5-[2-(4-chloro-2-nitrophenyl)diazen-1-yl]-6-hydroxy-1,4-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile

Test material form:

solid: particulate/powder

Sampling and analysis

Analytical monitoring:

no

Remarks:

water solubility (max. 0.0082 mg/L) too low

Test solutions

Vehicle:

no

Details on test solutions:

1. Substance weighed out and mixed with dilution water. Nominal loading rate: 1 mg/L.
2. Dispersion treated for 1 h in ultrasonic bath and 60 sec with Ultra-Turrax (8000 rpm).
3. Dispersion centrifugated for 10 min (6000 rpm).
4. Supernatant used as test medium.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Source (laboratory, culture collection): Pflanzenphysiologisches Institut Universiät Göttingen, Germany
- Age of inoculum (at test initiation): max. 1 week
- Method of cultivation: at 23°C in 24 h light

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Test temperature:

21 - 25°C

pH:

8.3 - 10.4

Nominal and measured concentrations:

1 mg/L nominal loading rate

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flask
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: glass, 300 mL nominal volume, 100 mL fill volume
- Aeration: no
- Initial cells density: 3.41 x 10^5 cells/mL
- Control end cells density: 1 x 10^4 cells/mL

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionised water + nutrient solution
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: 24 h

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: counting chamber; fluorimeter; spectrophotometer
- Chlorophyll measurement: yes

TEST CONCENTRATIONS
- Justification for using less concentrations than requested by guideline: insoluble in water

Reference substance (positive control):

not specified

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EL10

Effect conc.:

> 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EL10

Effect conc.:

> 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

No effects occured in the limit test. The total cell number in the test solution was higher than in the negative control (hormesis). Biomass (+34.5%) and growth rate (+8.3%) were both influenced positively compared to results in the negative control.

Any other information on results incl. tables

growth rate (control): 1.2 / d

growth rate (treatment): 1.3 / d

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The test item does not have any toxicity effect to freshwater green algae up to the limit of water solubility.