3,3'-dioctadecyl-1,1'-methylenebis(4,1-phenylene)diurea

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

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 (Carbon and Ammonium Oxidation))

Version / remarks:

Adopted 4th April 1984

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Version / remarks:

Adopted 30th May 1988

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No. of test material: 7ET2090
- Expiration date of the lot/batch: 31 December 2007
- Purity: 99 %

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature in the dark
- Stability under test conditions: Stable

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test item was not soluble, so test concentrations were prepared separately in Milli-RO water. An initial loading rate of 200 mg/L was magnetically stirred for at least 24 hours. After 24 hours, the synthetic sewage feed and sludge were added. A final loading rate of 100 mg/L was tested in duplicate. The test solutions were continuously stirred during the test, to ensure optimal contact between the test item and the test medium.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Details on inoculum
- Source of inoculum/activated sludge: An activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.

- Preparation of inoculum for exposure: Before use the sludge was coarsely sieved, washed and diluted with ISO-medium. In order to determine the number of suspended solids a small proportion of the sludge was weighed and dried overnight in an oven at 105°C. After collection, 50 ml of synthetic sewage feed was then added per litre of activated sludge. The sludge was kept aerated under test conditions until use.

- Concentration of suspended solids: 3.3 g/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

18.0 - 18.8 ⁰C

pH:

7.9 - 8.0

Nominal and measured concentrations:

Nominal test item concentration: 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:1 litre glass bottle.
- Aeration: Test media were aerated and stirred continuously
- No. of vessels per concentration (replicates): 2

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Details on results:

- Blank controls oxygen uptake rate: No inhibition (0 %) was observed in the blank controls.

Results with reference substance (positive control):

- Results with reference substance valid? The EC50 of the reference substance was within the accepted range of 5-30 mg/L (9 mg/L)

Reported statistics and error estimates:

None

Table 1- Controls (C) and test substance (T) : pH, oxygen concentration, oxygen consumption and percentage inhibition

Flask	Concentration (mg/L)	Oxygen concentration at the start (mg O2/L)	Oxygen consumption mg O2/L	% Inhibition	pH
C3	0	8.0	38		8.0
C4	0	8.1	37		8.0
Mean C3 + C4			37.5
T1	100	7.6	39	-7	7.9
T2	100	7.7	40	-7	8.0

 

Validity criteria fulfilled:

yes

Remarks:

The EC50 of the reference substance was within the accepted range of 5-30 mg/L (9 mg/L); the difference between the negative controls (mean respiration rate) was within 15% of each other (12% and 3 %),

Conclusions:

Under test conditions, the test item was not toxic to activated sludge bacteria at loading rate of 100 mg/L. Therefore, the NOEC and EC50 are considered to be ≥100 and >100 mg/L, respectively.

Executive summary:

Migchielsen (2006) is a GLP-compliant study following OECD guideline 209. The study is reliable without restrictions (Klimisch 1) as it followed a standard method. A blank control and reference item control were included in the test setup. As the test item was not soluble test concentrations were prepared separately. The test solutions were continuously stirred in a 1L glass bottle during the test, to ensure optimal contact between the test item and the test medium. After contact time the oxygen consumption of each sample was tested in a 300 mL oxygen bottle.

The EC50 of the reference substance was within the accepted range of 5-30 mg/L (9 mg/L); the difference between the negative controls (mean respiration rate) was within 15% of each other (12% and 3 %), therefore meeting the acceptability criteria of the test.

Under test conditions, the test item was not toxic to activated sludge bacteria at loading rate of 100 mg/L. Therefore, the NOEC and EC50 were ≥100 and >100 mg/L, respectively.

Description of key information

Under test conditions, the test item was not toxic to activated sludge bacteria at loading rate of 100 mg/L. Therefore, the NOEC and EC50 are considered to be ≥100 and >100 mg/L, respectively.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

EC10 or NOEC for microorganisms:

100 mg/L

Additional information

Migchielsen (2006) is a GLP-compliant study following OECD guideline 209. The study is reliable without restrictions (Klimisch 1) as it followed a standard method. A blank control and reference item control were included in the test setup. As the test item was not soluble test concentrations were prepared separately. The test solutions were continuously stirred in a 1L glass bottle during the test, to ensure optimal contact between the test item and the test medium. After contact time the oxygen consumption of each sample was tested in a 300 mL oxygen bottle.

The EC50 of the reference substance was within the accepted range of 5-30 mg/L (9 mg/L); the difference between the negative controls (mean respiration rate) was within 15% of each other (12% and 3 %), therefore meeting the acceptability criteria of the test.

Under test conditions, the test item was not toxic to activated sludge bacteria at loading rate of 100 mg/L. Therefore, the NOEC and EC50 were ≥100 and >100 mg/L, respectively.