3'-(trifluoromethyl)acetophenone

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

- mixed population of aquatic microorganisms (activated sludge)
- Origin: aeration tank of a wastewater plant treating predominantly domestic sewage (Wupper area water authority, WWTP Odenthal)
- Date of collection : 2017-07-24
- Concentration of sludge: 30 mg/L suspended solids

Pre-treatment of the inoculum
- Before use, the inoculum was stored for three days at room temperature under continuous stirring with aeration.
- the sludge was washed twice by adding mineral medium and centrifuging for 10 min at 2000 rpm and 20 °C and decanting off the supernatant.
- An aliquot of the wet sludge was dried in order to determine the wet weight / dry weight ratio of the sludge and to prepare a stock suspension (activated sludge) of 3 g dw/L.
- The calculated amount of sludge, needed to achieve 300 mL of this stock suspension, was dissolved in mineral medium and then filled up to a defined end volume.

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Pre-treatment of the test item
25 mg of the test item were weighed out and added to the test flasks, filled with 200 mL of mineral medium. Afterwards the volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg test item/L.

Pre-treatment of the reference compound sodium benzoate
25 mg of the reference compound were weighed out on aluminium foil and both were added to the test flasks, filled with 200 mL of mineral medium. Afterwards the volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg reference compound /L.

Pre-treatment of the toxicity control
25 mg of the test item and 25 mg of the reference compound weighed out on aluminium foil added to the test flasks, filled with 200 mL of mineral medium. Afterwards the flask volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg test item and reference compound/L.

Exposure conditions
- Test volume: 250 mL
- Test apparatus: OxiTopControl System (WTW)
- Mixing: 1 magnetic stirrer per test vessel
- Incubation time: 28 days
- Incubation temperature: 22 ± 1 °C
- Aeration of dilution water: yes
- Continuous darkness: yes
- pH: 7.4 - 8.1 after 28 days

Reference substance:

benzoic acid, sodium salt

Remarks:

Acros Organics, purity 99.9 %, batch A0357641

Parameter:

% degradation (O2 consumption)

Value:

16

Sampling time:

28 d

Details on results:

- The used concentration of the test item is not toxic to bacteria.

Results with reference substance:

Kinetic of reference substance ( % Degr.):
83 after 7 days
91 after 14 days
94 after 21 days
95 after 28 days

Validity criteria fulfilled:

yes

Remarks:

Ready biodegradability of reference compound >= 60 % within 14 d; toxicity control exhibited degradation rates > 25 % within 14 d; Replicates difference< 20%; Oxygen uptake of blank inoculum <= 60mg/L; no pH influence

Interpretation of results:

not readily biodegradable

Conclusions:

Within 28 days, a degradation rate of 16 % was determined for teh test substance.
The reference compound sodium benzoate showed 91 % degradation after 14 days.

Executive summary:

A study was performed to assess the ready biodegradability of the test substance in accordance with the Council Regulation (EC) No 440/2008, Method C.4-D “Manometric Respirometry Test“(2008). This test method is in all essential parts identical with OECD Guideline 301 F (adopted July 1992).

A suspension of 100 mg/L test item in a mineral medium, equalling to 50-100 mg ThOD or COD/Litre as the nominal sole source of organic carbon, was stirred in a closed flask and inoculated at a constant temperature (22 ± 1 °C) for up to 28 days under aerobic conditions in the dark.

The consumption of oxygen (BOD) was determined by measuring the drop in pressure in the automated respirometer flasks. Evolved carbon dioxide was absorbed in sodium hydroxide. The amount of oxygen taken up by the test item (corrected for uptake by blank inoculum, run in parallel) was expressed as a percentage of theoretical oxygen demand (ThOD).

The endogenous activity of the inoculum was checked running parallel blanks with inoculum but without test item. A reference compound (sodium benzoate) was run in parallel to check the operation of the procedures.

A toxicity control (test item and reference compound mixed, one replicate) was run in parallel, to ensure that the chosen concentration of the test item was not inhibitory to microorganisms.

Degradation was followed by the determination of oxygen uptake and measurements were taken at frequent intervals to allow the identification of the beginning and end of biodegradation and the slope of the biodegradation curve.

Because of the nature of biodegradation and of the mixed bacterial populations used as inoculum, determinations of test item and inoculum blank were carried out in triplicate and of reference compound in duplicate.

A degradation of 16% was determined for the test substance after 28 d. Therefore it is considered to be "not biodegradable.

The reference compund sodium benzoate showed 91 % degradation after 14 d.

Description of key information

A study was performed to assess the ready biodegradability of the test substance in accordance with the Council Regulation (EC) No 440/2008, Method C.4-D “Manometric Respirometry Test“(2008). This test method is in all essential parts identical with OECD Guideline 301 F (adopted July 1992).

A suspension of 100 mg/L test item in a mineral medium, equalling to 50-100 mg ThOD or COD/Litre as the nominal sole source of organic carbon, was stirred in a closed flask and inoculated at a constant temperature (22 ± 1 °C) for up to 28 days under aerobic conditions in the dark.

The endogenous activity of the inoculum was checked running parallel blanks with inoculum but without test item. A reference compound (sodium benzoate) was run in parallel to check the operation of the procedures.

A toxicity control (test item and reference compound mixed, one replicate) was run in parallel, to ensure that the chosen concentration of the test item was not inhibitory to microorganisms.

Degradation was followed by the determination of oxygen uptake and measurements were taken at frequent intervals to allow the identification of the beginning and end of biodegradation and the slope of the biodegradation curve.

Because of the nature of biodegradation and of the mixed bacterial populations used as inoculum, determinations of test item and inoculum blank were carried out in triplicate and of reference compound in duplicate.

A degradation of 16% was determined for the test substance after 28 d. Therefore it is considered to be "not biodegradable".

The reference compund sodium benzoate showed 91 % degradation after 14 d.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater