Cyclohexanone, 4-methoxy-

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:

14 Mar - 30 May 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1988

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Method: physico-chemical oxygen consumption
Controls: 3.5-Dichlorophenol, Purity 97%.
Test substance concentration: 1000, 1800, 3200, 5600, 10000 mg/L
Reference compound concentration: 2.5, 5, 10, 20 and 40 mg/L

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Source: aeration tank of a domestic sewage treatment plant (Municipal STP Cologne-Stammheim)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20 ± 2° C

pH:

7.0 to 7.5

Dissolved oxygen:

2.7 to 4.4 mg/L

Nominal and measured concentrations:

1000; 1800; 3200; 5600; 10000 mg/L (nominal concentrations)

Reference substance (positive control):

yes

Remarks:

3,5-Dichloronitrophenol, 2.5; 5; 10; 20; 40 mg/L

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

The physico-chemical oxygen consumption control is carried out, since some substances may consume oxygen by chemical reactivity. In order to be able to differentiate between physico-chemical oxygen consumption and biological oxygen consumption(respiration), at least the maximum concentration of the test item is additionally tested without activated sludge.

Results with reference substance (positive control):

Inhibition of up to 96.7 % at 40 mg/L.

Validity criteria for the measurement of the bacterial toxicity:

Target condition according to guideline:	Actual condition according to the study:	Validity criteria met:
In a 2004 international ring test organized by ISO using activated sludge derived from domestic sewage, the EC50 of 3,5-dichlorphenol was found to lie in the range 2 mg/L to 25 mg/L for total respiration. If the EC50 of 3,5-DCP does not lie in the expected range, the test should be repeated with activated sludge from another source.	The EC50 of the reference substance 3.5-dichlorophenol is in the range 5 - 30 mg/L.	Yes
The test should be performed at a temperature within the range 20 ± 2°C.	The test was performed between 20 ± 2°C.	Yes
The specific oxygen consumption of the controls shall be reported.	The oxygen consumption of the controls is stated.	Yes
Two control respiration rates are within 15% of each other.	The respiratory rates of the 2 controls differ less than 15 %.	Yes

 

Validity criteria fulfilled:

yes

Remarks:

See 'Any other information on results incl. tables'.

Conclusions:

The test substance showed 45.8 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/l.

Executive summary:

A study was performed to assess the toxicity of 4-Methoxycyclohexanone to bacteria.

The study was in accordance with the Commission Directive 88/302/EEC; Official Journal of the EGL133PartC.ll (1988).

The activated sludge was exposed to 4-Methoxycyclohexanone at different concentrations.

The respiration rate of each mixture was determined after aeration periods of 3 hours.

4-Methoxycyclohexanone showed 45.8 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/L.

 

The EC50 is higher than 10000 mg/L.

Description of key information

The test substance showed 45.8 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:

10 000 mg/L