Tetrabutylurea

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20.11.2012 to 23.11.2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

(2004)

GLP compliance:

yes (incl. QA statement)

Remarks:

Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Auf dem Aberg 1, Schmallenberg (Germany)

Test material

Test material information

Constituent 1

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:

Urea, N,N,N',N'-tetrabutyl-

IUPAC Name:

Urea, N,N,N',N'-tetrabutyl-

Details on test material:

- Name of test material (as cited in study report): Tetrabutyl urea
- Substance type: amide
- Physical state: liquid
- Analytical purity:99.6%
- Impurities (identity and concentrations): dibutylamine, water, chloride, sulfur
- Composition of test material, percentage of components: dibutylamine: 0.04%, water: 0.04%, chloride: 0.8 ppm, sulfur:<1 ppm
- Purity test date: 04.08.2012
- Lot/batch No.: 2011-11-4
- Expiration date of the lot/batch: 03.11.2013
- Storage condition of test material: test substance stored dry at room temperature (15-25°C) in the dark

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Freshly prepared test solutions at the beginning of the test and pooled samples of the test media at the end of the test were analysed for the test item using LC-MS/MS (duplicate samples of ca. 20 mL).

Test solutions

Vehicle:

no

Details on test solutions:

The highest test concentration was prepared by dissolving 4.30 mg of the test item in 1000 mL of sterile water and stirring for 2 hours at room temperature. The remaining four concentrations were prepared by dilution of the stock solution by a factor of 2.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Strain: Daphnia magna Straus
- Source: German Federal Environment Agency, Institut für Wasser-, Boden- und Lufthygiene
- Age at study initiation (mean and range, SD): <24 h
- Method of breeding: Adult Daphnia, at least 3 weeks old, were separated from the stock population by sieving. Batches of 30 - 50 animals were held at room temperature in ca. 1.8 L of dilution water for one week. During this week, the daphnids were fed daily with an algal suspension (Desmodesmus subspicatus) and feedingstuff Artemio® Fluid (JBL). Algae growing in the log-phase were centrifuged and the pellet was re-suspended in a few mL of medium. Thirty millilitres of this suspension was given to 1 L of medium. The water was changed once per week. New born Daphnia (between 4 - 23 h old) were removed by wide-bore pipette (to avoid damage) and isolated in fresh dilution water for at least 1 h prior to being added randomly to the test vessels containing the appropriate test or control media.
- Feeding during test: no

ACCLIMATION
- Acclimation period: not necessary
- Acclimation conditions (same as test or not): same as test
- Type and amount of food: daphnids were fed daily with an algal suspension (Desmodesmus subspicatus) and feedingstuff Artemio® Fluid (JBL). Algae growing in the log-phase were centrifuged and the pellet was re-suspended in a few mL of medium. Thirty millilitres of this suspension was given to 1 L of medium.
- Feeding frequency: daily
- Health during acclimation (any mortality observed): not applicable

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Test temperature:

20.8°C

pH:

test start: 7.63-8.14 (in all test vessels)
test end: 7.72-8.34 (in all test vessels)

Dissolved oxygen:

test start: 6.8-9.1 mg O2/L (in all test vessels)
test end: 8.4-8.7 mg O2/L (in all test vessels)

Nominal and measured concentrations:

control, 0.269, 0.538, 1.075, 2.15, and 4.30 mg/L nominal
control, 0.25, 0.55, 1.26, 2.25, and 4.76 mg/L geometric mean measured

Details on test conditions:

TEST SYSTEM
- Test vessel: glass beaker
- Type (delete if not applicable): the test vessels were covered with a glass pane
- Material, size, headspace, fill volume: glass/60 mL/10 mL/50 mL
- Aeration: no
- Type of flow-through (e.g. peristaltic or proportional diluter): test conducted under static conditions
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline
- Alkalinity: 1.6 mmol/L
- Conductivity: 239.4 µS/cm
- Culture medium different from test medium: no
- Intervals of water quality measurement: regularly (not further specified)

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16/8 h light/dark cycle
- Light intensity: 488-489 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): immobilisation, appearance, behaviour

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study: conducted
- Test concentrations: 0, 0.1, 1.0, and 10 mg/L nominal
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1.85 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Results with reference substance (positive control):

24 h EC50=1.03 mg/L

Reported statistics and error estimates:

Determination of ECx-values were performed by probit analysis. The computer software ToxRat Solutions was used for the statistical evaluations.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

In a study conducted according to OECD Guideline 202, the acute toxicity (48 h EC50) of tetrabutylurea to Daphnia magna was determined to be 1.85 mg/L based on the geometric mean measured concentrations.

Executive summary:

The acute toxicity of tetrabutylurea to Daphnia magna was investigated in a study conducted according to OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test; 2004). In this static test, 20 daphnids per concentration were exposed to nominal concentrations of 0, 0.269, 0.538, 1.075, 2.15, and 4.30 mg TBU/L for 48 h. The concentrations of tetrabutylurea in the test media were assessed by chemical analyses (LC/MS/MS). As the recovered tetrabutyl urea concentrations exceeded the 20 % range at the beginning of the test and decreased more than 20 % from the initial values during the test, the geometric mean for each test concentration was calculated resulting in actual concentrations of 0.25, 0.55, 1.26, 2.25 and 4.76 mg/L. The 48 h EC50 was determined to be 1.7 mg/L and 1.85 mg/L based on the nominal and geometric mean measured concentrations, respectively.

This study is classified as reliable without restriction and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

Results Synopsis

Test organism: Daphnia magna (<24 h old)

Test type: static

48 h EC50=1.85 mg/L based on geometric mean measured concentrations

Endpoint(s) effected: immobilisation