4-(trifluoromethoxy)aniline

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:

09/2019-07/2020

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))

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

not required

Details on sampling:

The exposure medium with the reference substance was prepared by adding 8 mL of the synthetic medium, 100 mL of activated sludge and a defined amount of the stock solution to achieve the test concentrations, and was filled up with deionised water to 250 mL and aerated at 20 ± 2°C. Control vessels (inoculated sample without test item) were prepared the same way.

Vehicle:

no

Details on test solutions:

Direct weighings were prepared to give the different test item concentrations. The test item was added into Erlenmeyer flasks (incubation vessels) to about 130 mL deionised water and was stirred before testing (equilibration phase) overnight for 17 hours. The pH was measured and ranged between pH 5.8-6.6. The pH was adjusted to pH 7.2-7.5 with NaOH. For the reference compound a stock solution at a concentration of 500 mg/L was prepared by dissolving 250 mg 3,5-Dichlorophenol in 5 mL of 1 N NaOH and diluting to 0.5 litre with deionised water. The pH was adjusted to pH 7 - 8 with HCl.

Test organisms (species):

activated sludge

Details on inoculum:

The sludge was settled and the supernatant was decanted. After centrifuging the sludge (15 min at 3500 rpm and 20°C) the supernatant was decanted again. Approximately 1 g of the wet sludge was dried in order to calculate the amount of wet sludge to achieve a concentration of activated sludge of 3 g/L (dry weight) suspended solids. The calculated amount of sludge was dissolved in synthetic medium and then filled up to a defined end volume with deionised water.

Test type:

not specified

Water media type:

not specified

Total exposure duration:

3 h

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

501 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.:

233 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.:

< 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Validity criteria fulfilled:

yes

Conclusions:

The EC50 is 501 mg/L. The EC10 is 233 mg/L. The NOEC is lower than 10 mg/L.

Executive summary:

A study was performed to assess the toxicity of 4-trifluoromethoxyanilin to bacteria. The EC50 is 501 mg/L. The EC10 is 233 mg/L. The NOEC is lower than 10 mg/L.

Description of key information

The EC50 is 501 mg/L. The EC10 is 233 mg/L. The NOEC is lower than 10 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

501 mg/L

EC10 or NOEC for microorganisms:

233 mg/L