4,4'-Methylene-bis-(3-chloro-2,6-diethylaniline)

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

No analytics performed

Vehicle:

yes

Details on test solutions:

The test substance was dissolved in an auxiliary solvent, 10% Tween 80-dimethylformamide, to give a preliminary stock solution of 100 mg/ml. An aliquot (50 ul) of this stock solution was added to each of the test replicate beakers giving a final test concentration of 10 mg/l. Solvent controls were prepared in the same manner using solvent only.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

A mixed population of activated sewage sludge micro-organisms was used as inoculum. The sample was collected from a predominantly domestic sewag treatment plant close to the test lab on 5 June 1996. The sample was maintained at 20 +/- 2°C with continuous aeration and used within 24 hours of collection. The pH was 8 and the suspended solids level of the sample was 2.8 g/l. Consequently, no adjustment of these characteristics was considered necessary.

Test type:

other: aerobic

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

None

Hardness:

Approximately 120 - 180 mg/l as CaCO3

Test temperature:

20 +/- 2°C

pH:

8.0

Dissolved oxygen:

02 consumption rates (mg O2/l/min):
- control: 0.422 - 0.436
- solvent control: 0.386 - 0.400
- test item: 0.400 - 0.407
- reference: 0.067 - 0.319

Salinity:

freshwater used

Nominal and measured concentrations:

Nominal concentration: 10 mg/l test item

Details on test conditions:

At t = 0, 16 ml of synthetic sewage was made up to 300 ml with water in a 1 litre glass beaker. An aliquot, 200 ml, of inoculum was added and the mixture aerated at approximately 0.5 - 1 litre per minute with compressed air via a narrow bore glass tube. Thereafter, at 15-minute intervals, further cultures were prepared following the same procedure but with the addition of appropriate amounts of test or reference substance to the vessels prior to
adjusting the volume and adding the inoculum. The series was completed by a second Control culture. The cultures were then incubated for a maximum of 3 hours at 19°C under normal laboratory lighting.

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (Aldrich Chemical Co Ltd, Batch no. 41205, Purity 97%). The reference substance was dissolved in dilution water with the aid of ultrasonic disruption.

Key result

Duration:

3 h

Dose descriptor:

IC50

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95% CL could not be calculated

Duration:

3 h

Dose descriptor:

IC0

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

3,5-dichlorophenol: EC50 (3 hours) = 8 mg/l

The highest test concentration employed in this study, 10 mg/l. was the highest test concentration in the test medium at which a stable dispersion could be formed with the solvent. Therefore. it was regarded as impossible to test at higher concentrations of P5367 in the test medium. The dispersion was stable, visually, for approximately 1 hour.

Validity criteria fulfilled:

yes

Conclusions:

The EC50 (respiration inhibition) value for P5367 with activated sewage sludge has been determined as > 10 mg/l for the 3 hour contact time.

Executive summary:

The study was performed 1996 as GLP-test following OECD-testing method 209 using a mixed population of activated sewage sludge micro- organisms. Due to the low solubility, the test item was dissolved in an auxiliary solvent, 10% Tween 80 dimethylformamide mixture. The test was performed under static conditions with a nominal test item concentration of 10 mg/l, which was the highest test concentration in the test medium at which a stable dispersion could be formed with the solvent. Therefore. it was regarded as impossible to test at higher concentrations of P5367 in the test medium. The IC50 was determined to be above the maximum tested concentration of 10 mg/l.

The EC50 (respiration inhibition) value for P5367 with activated sewage sludge has been determined as > 10 mg/l for the 3 hour contact time.

Description of key information

The study was performed in 1996 as GLP-test following OECD-testing method 209 using a mixed population of activated sewage sludge micro- organisms. Due to the low solubility, the test item was dissolved in an auxiliary solvent, 10% Tween 80 dimethylformamide mixture. The test was performed under static conditions with a nominal test item concentration of 10 mg/l, which was the highest test concentration in the test medium at which a stable dispersion could be formed with the solvent. Therefore. it was regarded as impossible to test at higher concentrations of P5367 in the test medium. The IC50 was determined to be above the maximum tested concentration of 10 mg/L. The EC50 (respiration inhibition) value for P5367 with activated sewage sludge has been determined as > 10 mg/L for the 3-hour contact time.

Key value for chemical safety assessment

EC50 for microorganisms:

10 mg/L

Additional information

Source: GLP-report