2-sec-butylcyclohexan-1-one

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:

September 19, 2017 to October 12, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

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

Principles of method if other than guideline:

The respiration rate of an activated sludge fed with a standard amount of synthetic sewage feed is measured after a contact time of three hours.
The respiration rate of the same activated sludge in the presence of several concentrations of the test substance under otherwise identical conditions is also measured.
The inhibitory effect of the test substance at a particular concentration is expressed as a percentage of the mean respiration rates of six controls. An EC50 value, and where possible, an EC10 and NOEC value, are calculated from determinations performed on a range of test substance concentrations.
Note: the highest concentration tested is 100 mg/l.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

FRESKOMENTHE
Lot No.:VE00419857
Purity 99.0%
Expiration date:September 14, 2018

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Activated sludge was obtained from a water treatment plant treating predominantly domestic sewage (Bois-de Bay, 1242 Satigny, Switzerland). The sludge was kept aerobic until being used on the next day. The pH was 7.5.
The suspended solids content was determined by drying 50 ml of the sludge and weighing: dry weight of suspended solids: 5.02 g/l.
By adding 1810 ml of water to 2690 ml of sludge, a concentration of suspended solids of 3.0 g/l was obtained. With the final dilution during the test, a concentration (i.e. in the range 0.8 to 1.6 g/l as recommended in ISO 8192-1986) was obtained.

Test type:

static

Water media type:

freshwater

Remarks:

domestic sewage sludge

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

20 +/- 2°C

pH:

7.5

Nominal and measured concentrations:

100 mg/L nominal concentration

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

The EC50 (3 hours) of 3,5-DiChloroPehnol is between 2 and 25 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

At the tested concentration (100 mg/l) no significant inhibition was observed.
Therefore:
EC50 (3 hours) of Freskomenthe > 100 mg/l;
EC10 (3 hours) of Freskomenthe > 100 mg/l;
NOEC (3 hours) of Freskomenthe = 100 mg/l;

Executive summary:

An activated sludge respiration inhibition test was performed with Freskomenthe. In a limit test a test concentration of 100 mg/l was tested.

At the tested concentration (100 mg/l) no significant inhibition was observed.

Therefore:

EC₅₀(3 hours) of Freskomenthe > 100 mg/l

EC₁₀(3 hours) of Freskomenthe > 100 mg/l

NOEC (3 hours) of Freskomenthe = 100 mg/l;

 

Description of key information

In the Activated sludge respiration inhibition test with Freskomenthe (Study No. 16-E165, GLP) dated on October 12, 2017 and performed according to the OECD Guideline No. 209, the EC50 (3 hours) of Freskomenthe has been determined to be greater than 100 mg/L. The EC10 (3 hours) was > 100 mg/L and the NOEC = 100 mg/L. No significant effects observed.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

EC10 or NOEC for microorganisms:

100 mg/L