N,N''-(methylenedi-4,1-phenylene)bis[N'-octyl]urea

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:

30/10/2002-30/10/2002

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

Version / remarks:

(1984)

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

the test solutions at 31.6, 100, 316 and 1000 mg/L were prepared by direct addition of the test item in the test vessels, followed by agitation of these solutions for a few minutes.
The test solution of 10 mg/L was prepared by diluting a stock (suspension in water) of 20 mg/L with dechlorinated water.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Origin: water treatment plant of Evreux
- Laboratory culture: before the test, the inoculum was maintained under agitation for one day.
- Method of cultivation: 50 ml of sewage feed were added per L, just before agitation
- Preparation of inoculum for exposure: the inocolum was maintained in the dark, at temperatures between 21 and 23 deg C. The aeration was performed at a rate of 0.5 to 1 L/min and the pH was adjusted to 6.0- 8.0 using NaHCO3 or HCl.
-Preparation: the inocolum was left to settle, the supernatant rejected, filtered and washed with dechlorinated water. The quantity of the suspended matter was 4g/L +/- 10%
- Initial inoculum concentration in test: 1.6 g/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

280 +/- 20 mg/L Ca CO3

Test temperature:

21 -23 deg C

pH:

6.0-8.0

Dissolved oxygen:

air inserted at a rate of 0.5 to 1 L/min

Nominal and measured concentrations:

Nominal
10; 31.6; 100; 316; 1000 mg/L
Measured
analysis not performed

Details on test conditions:

TEST SYSTEM
- Test vessel: flasks
- Type: not reported
- Material, size, headspace, fill volume: not reported
- Aeration: yes
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- Biomass loading rate: 1.6 g/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dechlorinated water
- Culture medium different from test medium: no


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : 3h-EC50 (oxygen concentration)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3
- Range finding study is the final study

Reference substance (positive control):

yes

Remarks:

3.5-dichlorophenol

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

Remarks:

respiration rate

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

Remarks:

respiration rate

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: yes
- As the respiration rate of the highest tested concentration (1000 mg/L) was equivalent to the respiration rate of the controls, the oxygen consumption of the four other test concentrations was not determined

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: inhibition of respiration; EC50 8.63 mg/L, 95% C.L. (7.17-10.2 mg/L)

Validity criteria fulfilled:

yes

Remarks:

The difference between the two control respiration rates was ≤ 15% (0%) and the EC50 value of the positive reference substance 3,5-dichlorophenol was between 5 and 30 mg/L (8.63 mg/L).

Conclusions:

Under the conditions of the current test, KY-EU has no effect on the microorganisms of a water treatment plant.
NOEC = 1000 mg/L
EC50 > 1000 mg/L

Executive summary:

An activated sludge respiration inhibition test was carried out according to OECD 209 (1984) and GLP.

Nominal concentrations of 10, 31.6, 100, 316 and 1000 mg/L were tested. As the respiration rate of the highest tested concentration (1000 mg/L) was equivalent to the respiration rate of the controls, the oxygen consumption of the four other test concentrations was not determined.

No effects were observed. Therefore, it was concluded that the NOEC was 1000 mg/L and the EC50 value was > 1000 mg/L.

The validity criteria were met and the study is considered to be reliable without restrictions.

Description of key information

Under the conditions of the current test, KY-EU has no effect on the microorganisms of a water treatment plant.
NOEC = 1000 mg/L
EC50 > 1000 mg/L

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

An activated sludge respiration inhibition test was carried out according to OECD 209 (1984) and GLP.

Nominal concentrations of 10, 31.6, 100, 316 and 1000 mg/L were tested. As the respiration rate of the highest tested concentration (1000 mg/L) was equivalent to the respiration rate of the controls, the oxygen consumption of the four other test concentrations was not determined.

No effects were observed. Therefore, it was concluded that the NOEC was 1000 mg/L and the EC50 value was > 1000 mg/L.

The validity criteria were met and the study is considered to be reliable without restrictions.