3-(benzothiazol-2-yl)-7-(diethylamino)-2-oxo-2H-1-benzopyran-4-carbonitrile

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

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)

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Remarks:

The test item and reference compound concentrations were not confirmed by analytical methods, they were based on nominal concentrations.

Vehicle:

no

Test organisms (species):

activated sludge

Test type:

not specified

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Remarks on exposure duration:

incubation time with permanent aeration

Test temperature:

20 +/- 2°C

pH:

pH of the suspension before application : 7.7
pH of the synthetic sewage feed : 7.5 ± 0.5
pH ranges after 3 hours incubation periods: 7.2 - 8.3

Salinity:

A synthetic waste water feed was prepared by dissolving the following amounts of substance per 1 litre of water.
16.0 g peptone
11.0 g meat extract
3.0 g urea
0.7 g NaCl
0.4 g CaCl2 x 2H2O
0.2 g MgSO4 x 7H2O
2.8 g K2HPO4

Nominal and measured concentrations:

100 mg/L (nominal)

Details on test conditions:

Test item concentration/s : 100 mg/L, 3 replicates
100 mg/L with ATU, 2 replicates
Control : 6 replicates
4 replicates with ATU
Test item concentration in physico-chemical oxygen consumption control : 100 mg/L
Concentration of reference compound 3,5-Dichlorophenol : 2.5, 5, 10, 20 and 40 mg/L
The test item and reference compound concentrations were not confirmed by analytical methods, they were based on nominal concentrations.
Test vessels : 300 mL glass Erlenmeyer flasks
Method of application : direct weighing
Test concentration of the activated sludge : 1200 mg/L suspended solids
Test temperature : 20 ± 2°C
Stirring period of the test item before start of incubation time : 17 hours
Incubation time : 3 hours with permanent aeration

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (Acros Organics, purity: 99.9%, Batch No.: A0357150))

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

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

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

Details on results:

Macrolex Fluoreszenzrot G showed 1.5 % respiration inhibition of activated sludge at the highest test item concentration of 100 mg/L. The results is the eman ouot of three measurements. Macrolex Fluoreszenzrot G showed no statistical significant difference of respiration inhibition of activated sludge between control and a limit test item concentration of 100 mg/L.

Results with reference substance (positive control):

Concentration of the reference compound 3,5-Dichlorophenol was 2.5, 5, 10, 20 and 40 mg/L. The reference compound showed 15.76, 23.84, 45.90, 76.32 and 83.87 % inhibition, respectively.

No inhibition was observed within the six replcated of the control.

Validity criteria fulfilled:

yes

Conclusions:

Macrolex Fluoreszenzrot G showed no significant inhibitory effect at a limit test concentration of 100 mg/L (nominal).

Executive summary:

The toxicity of Macrolex Fluoreszenzrot G was invetsigated according to OECD Guideline 209 and the EU method C.11. In order to do so, the activated sludge was exposed to Macrolex Fluoreszenzrot G at a limit test item concentration of 100 mg/L. The respiration rate of each mixture was determined after aeration periods of 3 hours. Macrolex Fluoreszenzrot G showed 1.5 % respiration inhibition of activated sludge at a test item concentration of 100 mg/L (nominal).

Based on this observation, the EC50 is determined to be higher than 100 mg/L (nominal) and the NOEC is equal or higher than 100 mg/L (nominal).

Description of key information

Macrolex Fluoreszenzrot G showed no significant inhibitory effect at a limit test concentration of 100 mg/L (nominal).