A mixture of: N-(4-chlorophenyl)-4-(2,5-dichloro-4-(dimethylsulfamoyl)phenylazo)-3-hydroxy-2-naphthalenecarboxamide; N-(4-chlorophenyl)-4-(2,5-dichloro-4-(methylsulfamoyl)phenylazo)-3-hydroxy-2-naphthalenecarboxamide

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:

1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study compliant to GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: OCDE n° 201 (1984) Directive CEE 87/302 (1987) - Partie C (1987)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

90 mg CaCO3/L

Nominal and measured concentrations:

25 - 50 - 75 - 90 and 100 % (volume by volume) test substance extracted in test medium

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.1 mg/L

Basis for effect:

biomass

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.1 mg/L

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 0.1 mg/L

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 0.1 mg/L

Basis for effect:

biomass

Details on results:

No inhibition of algal growth was recorded during the 72-hours study period, until 100% of test substance extract, maximum possible concentration of exposure

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

EC(I)50, for unicellular algea in freshwater medium: Higher than the limit of solubility

Executive summary:

The algal cultures (Scenedesmus subspicatus) were exposed to a test substance saturated solution for 72

hours.

The saturated solution (test substance extract) was prepared for the study by coarse filtration (paper filter)

of a test substance suspension, previously submitted to magnetic stirring for 4 hours 20 minutes.

A range-finding study (phase I) was performed using 25 - 50 - 75 - 90 and 100% (Volume by Volume)

test substance extract in test medium (3 cultures per concentration). A control group (6 cultures not

exposed to any substance) was also employed under the same experimental conditions.

As no inhibition was recorded during the 72-hour period, until 100% of test substance extract, the study

was considered as completed and no EC (I) 50 evaluation could be performed.

Test media were continously mechanically stirred, and randomly rotated each study day.

Algal cell concentrations have been recorded approximately 24 - 48 and 72 hours after the start of the

study.

Measurements of pH were performed for each concentration, at the start and at the end of the study.

Each test medium was twice sampled (at the beginning and at the end of the study). One supplementary

test flask, at the highest testcd concentration but without algae has been run under the same experimental

conditions, and sampled the same way.

The quality criterion for the study as notified in the O.E.C.O. and E.E.e:. protocols relative to the growth

in the control group, was respected.