Isobutylbenzene

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:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Isobutylbenzene

EC Number:

208-706-2

EC Name:

Isobutylbenzene

Cas Number:

538-93-2

Molecular formula:

C10H14

IUPAC Name:

(2-methylpropyl)benzene

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

Application of the test substance: Direct addition by initial weight into the test flasks. The test substance was weighed in the required amounts for the test concentrations directly to the test vessels.

Test organisms

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Source: municipal activated sludge; taken from the aeration tank of the wastewater treatment plant of Mannheim, Germany

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test conditions

Test temperature:

19.4 – 19.9 °C

pH:

7.4 (in the replicates, controls)

Dissolved oxygen:

Oxygen concentration during aeration: > 2 mg/L
Oxygen concentration immediately before measurement:> 7 mg/L

Nominal and measured concentrations:

Nominal: 0, 62.5, 125, 250, 500, 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Glas-beakers (nominal volume 1L)
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: Glass, 500 ml fill volumne
- Aeration: yes
- No. of vessels per concentration (replicates): 9
- No. of vessels per control (replicates): 6
- No. of vessels per abiotic control (replicates): 6
- Sludge concentration (weight of dry solids per volume): 1.5 g/L dw


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: accrding to OECD 209

OTHER TEST CONDITIONS
- Adjustment of pH: yes, with 1 M sodium hydroxide to pH 7.2 (stock solution)
- Photoperiod: not relevant
- Light intensity: not relevant

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : oxygen consumption after 3 hrs.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Effect concentrations 2

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

Results with reference substance (positive control):

EC50 of the positi9ve control 3,5-dichlorophenol was 6 mg/L

Reported statistics and error estimates:

The consumption rates were used for the determination of the ECx for the reference substance by the probit method based on Finney with the software TOXRAT Professional 2.10. The effect concentrations were given with an accuracy of 2 significant digits.