A mixture of: 2,4 -bis(N'-(4-methylphenyl)ureido)toluene; 2,6 -bis(N'-(4-methylphenyl)ureido)toluene

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 March 2003

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study has been performed according to OECD and/or EC guidelines and according to GLP principles. Limited information available to verify the composition of the used test substance.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

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

Reference substance name:

A mixture of: 2,4 -bis(N'-(4-methylphenyl)ureido)toluene; 2,6 -bis(N'-(4-methylphenyl)ureido)toluene

EC Number:

411-070-0

EC Name:

A mixture of: 2,4 -bis(N'-(4-methylphenyl)ureido)toluene; 2,6 -bis(N'-(4-methylphenyl)ureido)toluene

Molecular formula:

C23H24N4O2

IUPAC Name:

3-(2-methyl-5-{[(4-methylphenyl)carbamoyl]amino}phenyl)-1-(4-methylphenyl)urea

Details on test material:

- Name of test material (as cited in study report): KY-ET
- Substance type: white powder
- Physical state: solid
- Stability in water: at least 96 hours
- Storage condition of test material: RT in the dark

Sampling and analysis

Analytical monitoring:

not required

Test solutions

Vehicle:

no

Details on test solutions:

Theb test substance was quantitatively added to the test vessels. A nominal concentration of 100 mg/L was tested in duplicate.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source: Municipal sewage treatment plant "Waterschap de Maaskant", 's-Hertogenbosch, The Netherlands
- Pretreatment: Sludge was sieved, washed and diluted wtih tap water.
- Initial biomass concentration: 3.0 g/L

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

30 min

Test conditions

Test temperature:

19.0-22.0 degrees C

pH:

6.8-7.0

Nominal and measured concentrations:

100 mg/L nominal concentration; no concentrations were measured, but the solubility of KY-ET is very low (0.002 mg/L), so it can be assumed that the concentrations were at maximum solubility for KY-ET.

Details on test conditions:

TEST SYSTEM
- Test vessel: 1L glass test, 300 mL oxygen bottles
- Material, size, headspace, fill volume: test: 1L glass bottle with 500 mL fill volume
- Aeration: continuous during contact time (no aeration but stirring during oxygen measurement)
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per reference control (replicates): 3


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Milli-Q reverse osmosis purified tap water

OTHER TEST CONDITIONS
- Adjustment of pH: No

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Oxygen consumption

TEST CONCENTRATIONS
- Test concentration: 100 mg/L (nominal)

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Duration:

30 min

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

Details on results:

The test solution concentration of 100 mg/L (nominal) was presumably above the solubilityof KY-ET in water (0.002 mg/L). This test concentration (limit test level) showed no toxicity towards sludge microorganisms (1 and 4% inhibition).

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: 30% inhibition at 3.2 mg/L, 63% inhibition at 10 mg/L, 89% at 32 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The nominal EC50 value is > 100 mg/L.

Executive summary:

An activated sludge respiration inhibition study was performed according to OECD 209. The limit test was performed at nominal 100 mg/L, which is significantly above the solubility of KY-ET (0.002 mg/L). This test concentration showed no toxicity towards sludge microorganisms (1 and 4% inhibition). Therefore the nominal EC50 value is > 100 mg/L.