[No public or meaningful name is available]

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 9 August 2006 to 19 April 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study, GLP compliant; no restrictions, fully adequate for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Preparation of inoculum for exposure: Continuous aeration at a temperature of approximately 21ºC on the day of collection
- Initial biomass concentration: 3.9 g/l
- pH 7.4

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

None

Test conditions

Hardness:

140 mg/l as CaCO3

Test temperature:

21ºC

pH:

7.5 - 8.3

Dissolved oxygen:

5.7 - 8.8 mg O2/l

Nominal and measured concentrations:

320, 560, 1000, 1800, 3200 mg/l

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

30 min

Dose descriptor:

other: EC20

Effect conc.:

3 000 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 2

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 3 200 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 3

Duration:

30 min

Dose descriptor:

other: EC80

Effect conc.:

> 3 200 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 4

Duration:

30 min

Dose descriptor:

NOEC

Effect conc.:

1 800 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 5

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

1 300 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 6

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

1 900 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 1700-2100 mg/l

Effect concentrations 7

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

2 900 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 8

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

It was not possible to obtain an EC 50 and EC80 value at 30 minutes for the test material as no concentration tested resulted in greater than 50% inhibition after 30 minutes contact time.
It was not possible to obtain a 95% confidence limit for the test material after 30 minutes contact time as the data generated did not fit the models available for the calculation of this limit.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels:
EC20 = 2.1 (30 minutes); 1.8 (3 hours) mg/l
EC50 = 7.8 (30 minutes); 7.0 (3 hours) mg/l
EC80 = 29 (30 minutes); 26 (3 hours) mg/l