Pentyl 2-cyano-(3-(6-methoxybenzothiazol-2-ylimino)-2,3-dihydro-1H-isoindol-1-ylidene)acetate

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:

From Aug. 28, 2000 to Oct. 12, 2000

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:

Commission Directive 88/302/EEC; Official Journal of the EC L 133 Part C (1988)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

not required

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Direct weighing
- Incubation time: 3 h with permanent aeration

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Method of cultivation: aeration tank of a waste water treatment plant treating predominantly domestic sewage (Wupper area water authority)
- Pretreatment: aeration ofthe activated sludge; daily feed with synthetic medium
- pH of the suspension before application: 6.8
- Test concentration of the activated sludge: 400 mg/L suspended solids

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

No data

Test temperature:

20±2 °C

pH:

7.4-7.7

Dissolved oxygen:

No data

Salinity:

No data

Nominal and measured concentrations:

Nominal: 1000, 1800, 3200, 5600, 10000 mg/L

Details on test conditions:

Type of application: Direct weighing
Test concentration of the activated sludge: 400 mg/L suspended solids

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (97 % purity)

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

Details on results:

Test substance showed 32.1 % respiration inhibition of activated sludge at a test substance concentration of 10000 mg/L

Results with reference substance (positive control):

- Results with reference substance valid: Yes
- Ref. concentrations: 2.5, 5, 10, 20, 40 mg/L
- % Inhibition: 86.2 and 92.2 at 20 and 40 mg/L concentrations.
- EC50: 7.9 mg/L

Reported statistics and error estimates:

The EC values are determined by statistical methods (probit analysis).

Table 1. Results

Test concentration (mg/L)	Respiratory rate Test substance (mg/L. h)	Phys.-chem. O2-consumption (mg/L. h)	Respiratory rate Phys.-chem. O2-consumption (mg/L. h)	Inhibition (%)
1000	42.0	0.0*	42.0	0.0
1800	39.0	0.0*	39.0	0.0
3200	38.4	0.0*	38.4	0.0
5600	31.2	0.0*	31.2	18.5
10000	26.0	0.0	26.0	32.1
Control, Mean	38.3
Control 1	37.5
Control 2	39.0

 

* The physico chemical oxygen consumption is determined at 10000 mg/L test substance concentration. No physico-chemical oxygen consumption has been determined. Therefore lower concentrations of the test substance cause no physico chemical oxygen consumption (deduced values).

Validity criteria fulfilled:

yes

Conclusions:

Under the test conditions, the test substance showed 32.1 % respiration inhibition of activated sludge at a concentration of 10000 mg/L. The EC50 was determined to be > 10000 mg/L.

Executive summary:

A study was performed to assess the toxicity of test substance to bacteria according to Commission Directive 88/3021EEC; Official Journal of the EC L133 Part C (1988) and equivalent to OECD guideline 209 in compliance with GLP

The activated sludge was exposed to the test substance at different concentrations. The respiration rate of each mixture was determined after aeration periods of 3 h. The test substance showed 32.1 % respiration inhibition on activated sludge at a concentration of 10000 mg/L. The EC₅₀ could not be determined but would hypothetically be > 10000 mg/L.

Description of key information

The EC50 of the test substance could not be determined. The hypothetical EC50 for respiration inhibition in microorganisms would be > 10000 mg/L

Additional information

A study was performed to assess the toxicity of test substance to bacteria according to Commission Directive 88/3021EEC; Official Journal of the EC L133 Part C (1988) and equivalent to OECD guideline 209 in compliance with GLP

The activated sludge was exposed to the test substance at different concentrations. The respiration rate of each mixture was determined after aeration periods of 3 h. The test substance showed 32.1 % respiration inhibition on activated sludge at a concentration of 10000 mg/L. The EC₅₀could not be determined but would hypothetically be > 10000 mg/L.