Tetrabutylurea

Short-term toxicity to fish

Administrative data

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11.02.2013 to 15.02.2013

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

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Version / remarks:

(1992)

GLP compliance:

yes (incl. QA statement)

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, 1,1,3,3-tetrabutyl-

IUPAC Name:

urea, 1,1,3,3-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, sulfur, Cl
- Composition of test material, percentage of components: dibutylamine: 0.04%, water: 0.04%, sulfur: <1 ppm, Cl: 0.8 ppm
- Purity test date: 04.06.2012
- Lot/batch No.: 2011-11-4
- Expiration date of the lot/batch: 03.11.2013
- Storage condition of test material: test material stored dry at room temperature (15-25°C) in the dark

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

The concentrations of tetrabutyl urea in the test matrix were determined by liquid chromatography tandem mass spectrometry (LC-MS/MS). All test concentrations were measured at test start, after 48 hours (aged and fresh test matrix) and at the end of the test (after 96 h). The samples were analysed immediately on the sampling day.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test media solutions were prepared by dilution of stock solutions. The stock solutions were prepared by dissolving the test item in an appropriate volume of dilution water, followed by stirring for ca. 2 hours at room temperature.
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): no vehicle used
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no

Test organisms

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: zebrafish
- Source: own breeding
- Age at study initiation (mean and range, SD): not reported
- Length at study initiation (length definition, mean, range and SD): mean: 2.3 cm (range: 2.2-2.5 cm)
- Weight at study initiation (mean and range, SD): mean: 0.08 g (range: 0.07-0.10 g)
- Method of breeding: The fish were held in water of the same quality as used in the test (purified drinking water) until the start of the test.
- Feeding during test: no

ACCLIMATION
- Acclimation period: >=12 d
- Acclimation conditions (same as test or not): same
- Type and amount of food: fish were fed ad libitum with live brine shrimp nauplii and ground flake food TetraMinR; feeding was stopped 24 h before test start
- Feeding frequency: once daily
- Health during acclimation (any mortality observed): mortality <5%

Study design

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test conditions

Hardness:

total hardness of dilution water: 1.0 mmol/L

Test temperature:

temperature throughout the test: 23-23.1°C

pH:

pH values throughout the test: 7.9-8.3

Dissolved oxygen:

oxygen saturation throughout the test: 92-107%

Nominal and measured concentrations:

nominal concentrations: 0.269, 0.538, 1.08, 2.15, and 4.3 mg/L
geometric mean measured concentrations (0-96 h): 0.172, 0.365, 1.0, 1.75, and 2.59 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: glass aquaria
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: glass/12 L/-/ca. 5.6 L
- Aeration: yes
- Type of flow-through (e.g. peristaltic or proportional diluter): test conducted under semi-static conditions
- Renewal rate of test solution (frequency/flow rate): A complete renewal of test media was performed once during the test after 48 h
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- No. of vessels per vehicle control (replicates):
- Biomass loading rate: 0.1 g/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline
- Chlorine: <0.02 mg/L (total residual chlorine)
- Alkalinity: 1.3 mmol/L
- Ca/Mg ratio: according to guideline
- Conductivity: 203.7 µS/cm
- Culture medium different from test medium: no
- Intervals of water quality measurement: Temperature, pH and oxygen concentration of the water were measured in each vessel directly before adding the fish and afterwards daily

OTHER TEST CONDITIONS
- Adjustment of pH:
- Photoperiod: 12/12 h light/dark cycle
- Light intensity: not reported

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortality and clinical signs were recorded at 3 h, 24, h, 48 h, 72 h, and 96 h after the addition of fish to the test vessels

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study: performed
- Test concentrations: 0.5, 1.0, and 4.3 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.365 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: mortality and clinical signs

Effect concentrations 2

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

1.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% c.i.: 1.0-1.8 mg/L (geom. mean measured)

Reported statistics and error estimates:

LC10 and LC50 values were determined together with 95 % confidence intervals using Probit-analysis assuming log-normal distribution of the values by using the ToxRat® software. Additionally, the highest tested concentration of the test item at which no lethal or other effect was observed (NOEC) was reported.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of tetrabutyl urea to Danio rerio was investigated in a study conducted according to OECD Guideline 203. The 96 h LC50 was determined to be 1.4 mg/L based on geometric mean measured concentrations.

Executive summary:

The acute toxicity of tetrabutyl urea to Danio rerio was investigated in a study conducted according to OECD Guideline 203 (Fish, Acute Toxicity Test; 1992). In this semi-static test, 7 fish per concentration were exposed to nominal concentrations of 0, 0.269, 0.538, 1.075, 2.15, and 4.30 mg TBU/L for 96 h. The concentrations of tetrabutylurea in the test media were assessed by chemical analyses (LC/MS/MS). Analysis of test media revealed tetrabutyl urea concentrations between 60.3 and 92.2% of nominal. Therefore, the geometric mean for each test concentration was calculated resulting in actual concentrations of 0.172, 0.365, 1.0, 1.75 and 2.59 mg/L. The 96 h LC50 was determined to be 1.7 mg/L and 1.4 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 fish.

Results Synopsis

Test organism: Danio rerio

Test type: semi-static

96 h LC50=1.4 mg/L based on geometric mean measured concentrations

Endpoint(s) effected: mortality