4-tert-butyl-3-hydroxy-2,6-xylylacetonitrile

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study in compliance with GLP-criteria.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

4-tert-butyl-3-hydroxy-2,6-xylylacetonitrile

EC Number:

259-766-1

EC Name:

4-tert-butyl-3-hydroxy-2,6-xylylacetonitrile

Cas Number:

55699-10-0

Molecular formula:

C14H19NO

IUPAC Name:

2-(4-tert-butyl-3-hydroxy-2,6-dimethylphenyl)acetonitrile

Details on test material:

- Name of test material (as cited in study report): 4-tert-Butyl-3-hydroxy-2,6-xylylacetonitrile
- Physical state/ Appearance: Solid / white to yellowish
- Homogeneity: Homogeneous
- Storage conditions: Storage at room temperature

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

TEST SUBSTANCE:
The test substance was weighed in the required amounts for the test concentrations directly to the test vessels. Then 180 mL demineralized water were added. The mixtures were stirred for 20 ± 2 hours at room temperature.

REFERENCE SUBSTANCE:
0.5 g of the reference substance was added to about 800 mL of demineralized water and stirred at room temperature until the reference substance was completely dissolved. The pH value of the stock solution was measured and adjusted to 7.4 with 1 M sodium hydroxide solution. Following this the stock solution was made up to 1L with demineralized water. The stock solution appeared colourless-clear.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Activated sludge from the municipal wastewater treatment plant of Mannheim/Baden Württemberg, Germany was collected on 19 September 2007 from the aeration tank of the plant. The activated sludge suspension was washed 3 times with tap water and sieved with a fine woven mesh (mesh size about 1 mm). This suspension was adjusted to a concentration of 7.5 g/L dry weight and pre-aerated over night. After the pre-aeration the lost water of the suspension was replaced. An aliquot of this suspension was added to the test vessels to obtain a sludge concentration of 1.5 g/L dry substance.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test conditions

Test temperature:

ambient (20±2 °C)

Dissolved oxygen:

- Oxygen concentration during aeration: > 2.5 mg/L
- Oxygen concentration immediately before measurement: > 6.5 mg/L

Nominal and measured concentrations:

- Nominal concentrations: 0 (control), 62.5, 125, 250, 500 and 1000 mg/L.

Details on test conditions:

EXPERIMENTAL PROCEDURE:
8 mL of the synthetic medium were added to the test vessels with test substance preparations, which were prepared the previous day. Aliquots of the stock solution with reference substance were pipetted to the test vessels and made up with demineralized water to a volume 180 mL. After that 8 mL synthetic medium were pipetted in each test vessel with reference substance. To prepare the blank control assays 180 mL of demineralized water and 8 mL synthetic medium were mixed. The pH-values were measured in all test vessels. An adjustment was not necessary. 12 mL demineralized water were added to each test vessel. After addition of 50 mL of the inoculum suspension (dry weight 7.5 g/L) the incubation was started by aeration of the test vessels with pressure air. The vessels for the blank control assays were prepared according to the same procedure without addition of test- or reference substance. After 180 minutes incubation the mixtures in the test vessels were placed subsequently into a closed oxygen measuring cell. A chart recorder recorded the oxygen respiration rates. The oxygen consumption of the blank control BC1 was measured first. The oxygen consumption of the reference substance assays (RS) was measured in the sequence RS1, RS2 and RS3. Subsequently the oxygen consumption of the test substance assays was measured in the sequence TS1, TS2, TS3, TS4 and TS5. The oxygen consumption of the blank control BC2 was measured at last.

TEST PARAMETERS:
- Incubation time: 180 minutes
- Test vessels: Erlenmeyer-vessel (nominal volume 250 mL)
- Test volume: 250 mL
- Synthetic medium: 8 mL/vessel 100-fold concentrated OECD medium
- Duration of the measurement of oxygen consumption: 8 - 10 min
- Sludge concentration in the test vessel: 1.5 g/L
- Number of test assays per concentration: 1

Reference substance (positive control):

yes

Remarks:

3,5 dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

180 min

Dose descriptor:

EC10

Effect conc.:

490 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 2

Duration:

180 min

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

Results with reference substance (positive control):

EC50 = 6 mg/L

Reported statistics and error estimates:

The values were given with an accuracy of 2 significant digits. The degree of inhibition was evaluated by Probit analysis according to Finney.