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Diss Factsheets

Administrative data

Endpoint:
toxicity to microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Study period:
16.07.2012 to 18.07.2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report date:
2012

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
(2010)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
SGS INSTITUT FRESENIUS GmbH, Im Maisel 14, 65232 Taunusstein (Germany)

Test material

Constituent 1
Chemical structure
Reference substance name:
Tetrabutylurea
EC Number:
224-929-8
EC Name:
Tetrabutylurea
Cas Number:
4559-86-8
Molecular formula:
C17H36N2O
IUPAC Name:
1,1,3,3-tetrabutylurea
Constituent 2
Reference substance name:
1,1,3,3-Tetrabutyl urea
IUPAC Name:
1,1,3,3-Tetrabutyl urea
Details on test material:
- Name of test material (as cited in study report): Tetrabutyl urea, 1,1,3,3-Tetrabutyl urea
- Substance type: amide
- Physical state: colourless to yellowish liquid
- Analytical purity: 99.6%
- Impurities (identity and concentrations): dibutylamine: 0.04%; water: 0.04%, Cl: 0.8 ppm; S: < 1 ppm
- Purity test date: 2012-05-14
- Lot/batch No.: 2011-11-4
- Expiration date of the lot/batch: 2013-11-03
- Storage condition of test material: test substance stored dry and in tight closed container at 15-25°C in the dark

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Due to the low water solubility, the test substance concentrations were introduced into the test vessels by direct weighing.
- Controls: performed
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): no vehicle used
- Evidence of undissolved material (e.g. precipitate, surface film, etc): not reported

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
-Inoculum: Activated sludge was collected from the effluent of the aeration tank of the municipal sewage treatment plant at Taunusstein-Bleidenstadt (Germany) dealing predominantly domestic sewages.
- Laboratory culture: no
- Preparation of inoculum for exposure: Immediately after receipt in the laboratory the activated sludge was washed twice with mineral medium acc. to OECD 301 B and aerated thereafter until test start. 10 L of the washed sludge were fed with 500 mL of the synthetic sewage. The feeding procedure was repeated one day after receipt.
- Pretreatment: no
- Initial biomass concentration: 1.5 g/L dry mass in the test treatments

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h

Test conditions

Test temperature:
20 +/- 2°C
pH:
in the definitive test
at the beginning of incubation: 7.08-7.62 (in all test vessels)
after incubation: 7.75-8.30 (in all test vessels)
Nominal and measured concentrations:
62.5, 125, 250, 500, and 1000 mg/L nominal
Details on test conditions:
TEST SYSTEM
- Test vessel: glass bottle
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: glass/250 mL/no/250 mL
- Aeration: yes
- Type of flow-through (e.g. peristaltic or proportional diluter): test conducted under static conditions
- No. of organisms per vessel: not applicable
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 6
- No. of vessels per autoxidation control: 1 (performed with the highest test concentration)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Synthetic sewage was prepared according to OECD Guideline 209 . Adjustment of pH was not necessary (the criterion of the guideline was fulfilled: pH of the solution: 7.14; according to guideline: pH 7.5 +/- 0.5). Tap water was used to prepare the test concentrations.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): inhibition of total respiration, heterotrophic respiration, and respiration due to nitrification

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study
- Test concentrations: 10, 100, and 1000 mg/L
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
yes
Remarks:
3,5 Dichlorophenol

Results and discussion

Effect concentrationsopen allclose all
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
500 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: total respiration
Duration:
3 h
Dose descriptor:
LOEC
Effect conc.:
1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: total respiration
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
Remarks on result:
other: total respiration
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
>= 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: heterotrophic respiration
Duration:
3 h
Dose descriptor:
LOEC
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: heterotrophic respiration
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: heterotrophic respiration
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
500 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of nitrification rate
Duration:
3 h
Dose descriptor:
LOEC
Effect conc.:
1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of nitrification rate
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 nitrification rate
Results with reference substance (positive control):
The EC50 of the reference item 3,5-Dichlorophenol for total respiration was in the required range of 2-25 mg/L (65% inhibition at 15 mg/L)
Reported statistics and error estimates:
Statistic evaluation of EC values was done using the commercially available computer program ToxRatPro Version 2.10

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
In a study conducted according to guideline, the respiration inhibition (total respiration, heterotrophic respiration, and respiration due to nitrification) of Tetrabutyl urea to activated sludge was found to be low (NOEC>=500 mg/L, LOEC>=1000 mg/L, and EC50>1000 mg/L).
Executive summary:

The toxicity of Tetrabutyl urea to activated sludge was investigated in a study conducted according to OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test) in the version dated 22 -Jul-2010. Activated sludge from the aeration tank of a municipal sewage treatment plant treating predominantly domestic waste was exposed to Tetrabutyl urea at different concentrations (range: 62.5 to 1000 mg/L nominal). After 3 h of incubation the inhibition of respiration was determined in comparison to a set of test solutions without any test substance. The NOEC values for inhibition of total respiration, heterotrophic respiration, and respiration due to nitrification were determined to be 500, >=1000, and 500 mg/L nominal, respectively. The corresponding LOEC and EC50 values were 1000, >1000, and 1000 mg/L (LOEC) and >1000 mg/L nominal (EC50 each), respectively.

The study is regarded as reliable without restriction and satisfies the requirements of the guideline.

Results Synopsis

Test organism: activated sludge

-inhibition of total respiration

NOEC: 500 mg/L

LOEC: 1000 mg/L

EC50: >1000 mg/L

-inhibition of heterotrophic respiration

NOEC: >=1000 mg/L

LOEC: >1000 mg/L

EC50: >1000 mg/L

-inhibition of the respiration due to nitrification

NOEC: 500 mg/L

LOEC: 1000 mg/L

EC50: >1000 mg/L (all values refer to nominal concentrations)

Endpoint(s) effected: respiration