4-propylcyclohexanone

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:

1996-08-05 to 1996-08-08

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

exposure period of 30 minutes instead of 3 hours

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: Laboratory plant which is mainly operated with municipal sewage (südlicher Wupperverband)
- Pretreatment: No

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Test temperature:

20 ± 2 °C

pH:

7.4 - 7.8

Nominal and measured concentrations:

Nominal: 100, 180, 320, 560 and 1000 mg/L
No measured concentrations

Details on test conditions:

TEST SYSTEM
- Aeration: Continuous aeration
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- No. of vessels per abiotic control (replicates): 1
- Sludge concentration: 800 mg/L

Reference substance (positive control):

yes

Remarks:

3,5-dichlorphenol

Key result

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

806 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: EC50 = 11 mg/L

Results

	Conc. [mg/L]	Amount mg/250 mL	O2 (start) mg O2/L	O2 (end) mg O2/L	Time [min]	Temp. [°C]	pH
Test item	100	25	5.2	3.0	2	20.7	7.6
	180	45	6.3	3.1	3	20.9	7.6
	320	80	6.0	2.9	3	20.7	7.6
	560	140	6.2	2.8	4	21.0	7.5
	1000	250	6.2	3.9	5	20.8	7.4
Control 1			5.7	3.3	2	19.3	7.8
Control 2			6.2	3.4	2	21.0	7.6
abiotic control	10000	2500	10	10	10	20.9	7.4

Concentration [mg/L]	Respiration rate of test item [mg/L*h]	Abiotic O2 consumption	Respiration – abiotic O2 consumption	Inhibition [%]
100	66.0	0.0*	66.0	15.4
180	64.0	0.0*	64.0	17.9
320	62.0	0.0*	62.0	20.5
560	51.0	0.0*	51.0	34.6
1000	27.6	0.0*	27.6	64.6
Control 1	78.0
Control 2	72.0
Control(mean)	84.0

* Abiotic O2-consumption was determined at a test substance concentration of 10000 mg / L.Since no abiotic O2-consumption was determined in this study, even lower concentrations of the test substance do not cause O2-consumption (estimated values).

Validity criteria fulfilled:

yes

Conclusions:

The toxic effects of the test substance on the oxygen consumption rate of aerobic microorganisms (activated sludge) after 30 min was determined according to the OECD 209. The EC50 was determined to be 806 mg/L.

Executive summary:

The influence of the test item on the activity of activated sludge was evaluated by measuring the respiration rate under defined conditions according to the OECD TG 209. A defined amount of activated sludge is mixed with synthetic medium and the respiratory rate is measured. This rate of respiration is compared to that measured in test mixtures with different concentrations of the test substance. The test substance was tested at the following concentrations: 100, 180, 320, 560 and 1000 mg/L. The sensitivity of the activated sludge used is checked with 3,5-dichlorophenol as reference substance. In this Activated Sludge, Respiration Inhibition Test an EC50 after 30 min of 806 mg/L was determined.

Description of key information

The toxic effects of the test substance on the oxygen consumption rate of aerobic microorganisms (activated sludge) after 30 min was determined according to the OECD 209. The EC50 was determined to be 806 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

806 mg/L

Additional information

The influence of the test item on the activity of activated sludge was evaluated by measuring the respiration rate under defined conditions according to the OECD TG 209. A defined amount of activated sludge is mixed with synthetic medium and the respiratory rate is measured. This rate of respiration is compared to that measured in test mixtures with different concentrations of the test substance. The test substance was tested at the following concentrations: 100, 180, 320, 560 and 1000 mg/L. The sensitivity of the activated sludge used is checked with 3,5-dichlorophenol as reference substance. In this Activated Sludge, Respiration Inhibition Test an EC50 after 30 min of 806 mg/L was determined (reference 6.1.7-1).