Bontron E-108

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11 and 12 December 2001.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Details on test material:

- Name of test material (as cited in study report): S178207
- Physical state: Powder
- Analytical purity: 91.4% w/w total ligand, 25.9% w/w free ligand and 69.1% w/w for the strength of S178207
- Lot/batch No.: NBZ 0155/44
- Stability under test conditions: stable
- Storage condition of test material: in the dark at ambient temperature

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

yes

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

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 2

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Any other information on results incl. tables

The results are shown in Table 2 (see attached background material).

Undissolved test substance was observed in the 10, 32 and 100 mg/l nominal S178207 test concentrations.

In test flasks dosed with S178207, <10% inhibition was observed in all the tested concentrations.

The median effective concentration (EC50) is defined as the concentration, estimated from the data obtained, resulting in a 50% reduction in the respiration rate of activated sludge within the period of the test, therefore:

3 hour EC50 > 100 mg/l

The 20% and 80% effect concentrations (EC20 and EC80) are defined as the concentrations tested, estimated from the data obtained, resulting in 20 and 80% reduction, respectively, in the respiration rate of activated sludge with the period of the test, therefore:

3 hour EC20 > 100 mg/l

3 hour EC80 > 100 mg/l

The 10% effect concentration is defined as the concentration tested, estimated from the data obtained, resulting in a 10% reduction in the respiration rate of activated sludge within the period of the test. Percentage inhibition less than or equal to 10% was within the expected experimental variability of the test and was considered not to be an effect of S178207. In this test the no observed effect concentration (NOEC) is equivalent to the EC10, therefore:

3 hour NOEC = 100 mg/l.

The reference substance, 3,5 -dichlorophenol, caused substantial inhibition of the respiration rate of the activated sludge. From the results obtained the 3 hour EC50 value was estimated to be 22 mg/l. This is within the expected normal range of 5 to 30 mg/l indicating the sludge was responding normally and confirming the viability of the sludge organisms.

The respiration rates in the two control flasks were within 15% of each other. Therefore, the mean control respiration rate was used in calculation of the percentage inhibition.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The 3 hour EC50 was found to be >100 mg/l. The 3 hour NOEC was found to be 100 mg/l.

Executive summary:

The guideline used for this study was OECD Guideline No. 209, Activated Sludge, Respiration Inhibition Test.

The duration of the test was 3 hours, and was conducted at a nominal temperature of 20°C.

The 3 hour EC50 of the substance was determined to be >100 mg/l. (Results based on nominal concentrations).