(Benzyloxycarbonyl)methyl 4-(1-Butyl-5-cyano-1,6-dihydro-2-hydroxy-4-methyl-6-oxo-3-pyridylazo)-benzoate

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From July 29th, 2002 to July 31st, 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

1984

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Version / remarks:

1988

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Yellow 6314-PPT

IUPAC Name:

Yellow 6314-PPT

Test material form:

solid

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test conditions

Test temperature:

20 °C

pH:

6.7-7.6 test item
6.7-7.7 control

Dissolved oxygen:

7.5-8.6 test item
8.4-8.7 control

Nominal and measured concentrations:

Nominal concentrations: 0, 32, 100, 320 and 1000 mg/l.

Details on test conditions:

Continuous aeration during 3-hours test period.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol at 5, 16, 50 mg/l

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Effect concentrations 2

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

Up to and includíng the highest concentration of 1000 mg/l the test item had no significant inhibitory effect (<15 %) on the respiration rate of activated sludge after the incubation period of 3 hours. The inhibition of the respiration rates of the activated sludge after the incubation period was in the range of 0.6 to 11.5 % compared to the controls.
All test concentrations were above the water solubility limit of the test item under the present test conditions. Thus, the 3-hour NOEC (EC15) of the test item to activated sludge microorganisms under the present test conditions was at least at the limit of water solubility, or at least 1000 mg/l.
The 3-hour EC20, EC50 and EC80 could not be calculated, but were clearly higher than the water solubility limit of the test item under the present test conditions, or higher than 1000 mg/l.

Results with reference substance (positive control):

The results confirmed the suitability of the activated sludge and the method used.

Applicant's summary and conclusion

Conclusions:

NOEC (3h) = 1000 mg/l (nominal concentration).