C16-(branched), C20-(branched) and C24-(branched)-alkanes

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21. Dec. 1993 - 22. Dec. 1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

yes

Remarks:

see principles of method if other than guideline

Principles of method if other than guideline:

The test organismus Pseudomonas putida was used. Culture medium, bacterial culture and the test substance in several concentrations were incubated in sealed 100 mL BOD flasks for 5.25 hours at 24.6 - 25.4 °C in a shaking incubator. The oxygen content was measured at 0h and 5.25h, consumption values for control and test substance preparations were then calculated, and EC values were derived.

GLP compliance:

yes

Analytical monitoring:

not required

Details on sampling:

- Concentrations: 0.1, 0.5, 1.0, and 2.0 mL/L

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: test substance was directly pipetted into the test flask
- Chemical name of vehicle (emulsifier): Nonylphenole ethoxypropoxylat
- Concentration of vehicle in test medium: 1 mL emulsifier stock solution per flask (stock solution: 10 mL emulsifier in 190 mL Aqua bidest.

Test organisms (species):

Pseudomonas putida

Details on inoculum:

- Laboratory culture: inhouse culture, originally obtained from the "Institut für Wasser-, Boden- und Lufthygiene, Berlin, Germany"
- Preparation of inoculum for exposure: liquid culture
- Initial biomass concentration: 1E +06 cells/mL

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

5.25 h

Post exposure observation period:

none

Test temperature:

24.6 - 25.5 °C

Nominal and measured concentrations:

nominal concentrations: 0.1, 0.5, 1.0, and 2.0 mL/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed
- No. of vessels per concentration: 2
- No. of vessels per control: 4
- Material, size, headspace, fill volume: 100 mL BOD flasks
- Aeration: none

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : oxygen concentration at start and end of exposure (-oxygen consumption)

TEST CONCENTRATIONS: 0.1, 0.5, 1.0 and 2.0 mL/L

Reference substance (positive control):

not required

Duration:

5.25 h

Dose descriptor:

EC10

Effect conc.:

> 2 other: mL/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

EC10 > 2.0 mL/L

Results with reference substance (positive control):

none

	Control	0.1 mL/L	0.5 mL/L	1.0 mL/L	2.0 mL/L
Mean O2concentration at study start	8.06	8.14	8.17	8.12	8.12
Mean O2concentration at study end	3.44	3.30	3.31	3.36	3.30
O2 consumption	4.62	4.84	4.86	4.77	4.82
Difference control - exposure		- 0.23	- 0.25	- 0.15	- 0.20
% effect of exposure		- 4.9	- 5.3	- 3.3	- 4.3

Validity criteria fulfilled:

yes

Conclusions:

EC10 > 2.0 mL/L.

Executive summary:

Tetrabutan, dest. potential toxicity towards microorganisms was tested in an oxygen consumption test using Pseudomonas putida.As the test substance is only poorly soluble in water, an emulsifier was used to obtain homogenously dispersed test substance preparation of 0.1, 0.5, 1.0 and 2.0 mL/L. No effects of these concentrations of Tetrabutan, dest. on the oxygen consumption of Pseudomonas putida after 5.25 hours of exposure were recorded. Thus, the EC10 > 2.0 mL/L.

Description of key information

Tetrabutan, dest. is not toxic to bacteria, as tested in an oxygen consumption test with Pseudomonas putida. The EC10 > 2.0 mL/L.

Key value for chemical safety assessment

EC50 for microorganisms:

2 mg/L

Additional information

Tetrabutan, dest. potential toxicity towards microorganisms was tested in an oxygen consumption test using Pseudomonas putida. As the test substance is only poorly soluble in water, an emulsifier was used to obtain homogenously dispersed test substance preparations of 0.1, 0.5, 1.0 and 2.0 mL/L. No effects of these concentrations of Tetrabutan, dest. on the oxygen consumption of Pseudomonas putida after 5.25 hours of exposure were recorded. Thus, the EC10 > 2.0 mL/L.