2-nitro-4-(trifluoromethyl)benzonitrile

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

02 Jan - 26 Feb 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2-nitro-4-(trifluoromethyl)benzonitrile

EC Number:

212-298-1

EC Name:

2-nitro-4-(trifluoromethyl)benzonitrile

Cas Number:

778-94-9

Molecular formula:

C8H3F3N2O2

IUPAC Name:

2-nitro-4-(trifluoromethyl)benzonitrile

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Type: Mixed population of aquatic microorganisms (activated sludge)
- Source of inoculum/activated sludge: Aeration tank of a wastewater plant treating predominantly domestic sewage (Wupper area water authority, STP Odenthal). Date of collection: 2007-01-02
- Storage conditions: The inoculum was stored at room temperature under continuous shaking with aeration until use.
- Storage length: The inoculum was stored for max. 3 days.
- Pretreatment: The sludge was washed twice by adding mineral medium, centrifuging (10 min at 2000 rpm and 20 °C) and decanting off the supernatant. 1.135 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 wet) suspended solids. The calculated amount of sludge was first dissolved in mineral medium and then filled up to a defined end volume.
- Concentration of sludge: 30 mg/L ss

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: The mineral medium was prepared from stock solutions of mineral components described as follows:
1. Mineral salt solution: Potassium dihydrogen phosphate (KH2PO4) 85.0 g, Dipotassium hydrogenphosphate (K2HPO4) 217.5 g, Disodium hydrogenphosphate dihydrate (Na2HPO4 * 2H2O) 334.0 g, Ammonium chloride (NH4Cl) 5.0 g, The components were dissolved in deionized water and filled up to 10 litres. The pH of the solution was adjusted to 7.4
2. Magnesium sulphate solution: Magnesium sulphate heptahydrate (MgSO4 * 7H2O) 22.5 g, The substrate was dissolved in deionized water and filled up to 1 litre.
3. Calcium chloride solution: Calcium chloride dehydrate (CaCl2 * 2H2O) 36.4 g. The substance was dissolved in deionized water and filled up to 1 litre.
4. Iron (III) chloride solution: Iron (III) chloride hexahydrate (FeCl3 * 6H2O) 0.25 g. The substance was dissolved in deionized water and filled up to 1 litre.
To prepare the mineral medium 10 mL of the mineral salt solution were mixed with 800 mL deionized water. Then 1 mL each of the magnesium sulphate-, calcium chloride- and the iron (III) chloride solution were added and filled up to 1 litre with deionised water.
- Preparation of test flasks with test item: 25 mg of the test item were weighted out on aluminium foil. Test item and aluminium foil were added to the test flasks, which had already been filled with 200 mL of mineral medium. Afterwards the flask content was made up to 250 mL with mineral medium containing inoculum to give a test concentration of 100 mg test item/L.
- Test temperature: 22 ± 1 °C
- pH: 7.4
- pH adjusted: Only the pH of mineral salt medium was adjusted.
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Oxi Top System (WTW)
- Test volume: 250 mL
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: One magnetic stirrer in each test vessel.
- Measuring equipment: Continous Flow Analyser SKALAR SAN Plus System
- Other: 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.
Oxygen uptake: The oxygen uptake was calculated from the readings at regular and frequent intervals, using the method given by the manufacturer of the equipment.
Other measurements: At the end of incubation, the pH of the contents of the flasks was measured.

SAMPLING
- Sampling frequency: daily
- Sampling method: Determination of nitrite nitrogen and nitrate nitrogen and the sum of both by flow analysis (CFA and FIA) and spectrometric detection using a Continuous Flow Analyser SKALAR SAN Plus System

CONTROL AND BLANK SYSTEM
- Inoculum blank: Inoculum blank was carried out in triplicate samples.
- Toxicity control: Toxicity control was carried out in one replicate.
- Reference substance: A positive control was carried out in duplicate samples.

Reference substance

Reference substance:

benzoic acid, sodium salt

Remarks:

100 mg reference compound/L

Results and discussion

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Details on results:

Within 28 days, a degradation of 0.0% was determined for 2-nitro-4-(trifluoromethyl)benzonitrile. 2-nitro-4-(trifluoromethyl)benzonitrile is considered to be "Not Readily Biodegradable".

BOD5 / COD results

Results with reference substance:

The reference compound sodium benzoate showed 82.8% degradation after 14 days and 85.7% degradation after 28 days.

Any other information on results incl. tables

 Table 1: Degradation of test item

Time (d)	Corrected BOD test item (a-bm) (mg O2/L)		% degradation of test item		% degradation mean of test item	% degradation mean of reference compound	% degradation mean of toxicity control
	a1	a2	a1	a2
0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
1	0.5	0.0	0.6	0.5	0.3	30.1	3.0
2	0.0	0.0	0.0	0.0	0.0	51.2	37.8
3	0.0	0.0	0.0	0.0	0.0	62.9	47.3
4	0.0	0.0	0.0	0.0	0.0	68.3	49.3
5	0.0	0.0	0.0	0.0	0.0	72.0	51.0
6	0.0	0.0	0.0	0.0	0.0	74.4	52.4
7	0.0	0.0	0.0	0.0	0.0	76.6	52.4
8	0.0	0.0	0.0	0.0	0.0	79.0	53.3
9	0.0	0.0	0.0	0.0	0.0	79.7	54.1
10	0.0	0.0	0.0	0.0	0.0	80.9	54.3
11	0.0	0.0	0.0	0.0	0.0	81.5	55.3
12	0.0	0.0	0.0	0.0	0.0	81.8	55.4
13	0.0	0.0	0.0	0.0	0.0	82.4	55.4
14	0.0	0.0	0.0	0.0	0.0	82.8	55.8
15	0.0	0.0	0.0	0.0	0.0	82.8	56.2
16	0.0	0.0	0.0	0.0	0.0	83.4	56.0
17	0.0	0.0	0.0	0.0	0.0	82.8	56.0
18	0.0	0.0	0.0	0.0	0.0	83.7	56.0
19	0.0	0.0	0.0	0.0	0.0	83.5	56.7
20	0.0	0.0	0.0	0.0	0.0	84.1	56.5
21	0.0	0.0	0.0	0.0	0.0	84.1	57.7
22	0.0	0.0	0.0	0.0	0.0	83.5	57.3
23	0.0	0.0	0.0	0.0	0.0	84.7	57.7
24	0.0	0.0	0.0	0.0	0.0	84.4	57.5
25	0.0	0.0	0.0	0.0	0.0	85.0	57.9
26	0.0	0.0	0.0	0.0	0.0	85.4	58.5
27	0.0	0.0	0.0	0.0	0.0	84.8	58.5
28	0.0	0.0	0.0	0.0	0.0	85.7	58.8

 

 

Table 2: Validity criteria for OECD 301.

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	At the end of the test, biodegradation (%) in parallels with test item did not differ by more than 20%.	yes
Percentage degradation of the reference compound reached the pass level by day 14 (≥ 60%).	Percentage degradation of the reference compound reached with 82.8% degradation the pass level by day 14 (≥ 60%).	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	The degradation in the toxicity control was 55.8% at day 14.	yes

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

see Table 2 in "Any other information on results incl. tables".

Interpretation of results:

under test conditions no biodegradation observed