5-Brom-2-[(3,4,5-trifluorphenoxy)-difluormethyl]-1,3-difluorbenzene

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:

11 Nov 2017 - 20 Jan 2018

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))

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on sampling:

- Concentrations: 1000 mg/L were weighed out directly in Erlenmeyer flasks, 3 replicates, no vehicle
- Control (test medium without test or reference item): Triplicates at the beginning and at the end of the test
- The oxygen uptake rates of all samples were determined following an incubation time of 3 hours.

Vehicle:

no

Details on test solutions:

Preparation of the test item solution:
Test item: 500 mg/L
Synthetic waste water: 500 mL
Demineralized water: filled up to 250 mL
Inoculum: 250 mL

Preparation of the reference item solution:
Reference item: 58, 100, 180 mg/L
Synthetic waste water: 16 mL
Demineralized water: filled up to 250 mL
Inoculum: 250 mL

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Species: non-adapted, activated sludge, micro organisms from a domestic waste water treatment plant.
Origin: supplied by the municipal sewage plant of Hildesheim, Germany
Dry sludge concentration: 2.80 g/L (corresponding to 1.40 g/L suspended solids in the test vessels)

The sludge was washed twice with chlorine free tap water and adjusted to a dry sludge concentration of 3.0 g/L +/- 10 %. The sludge was used within 24 h after sampling

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

nominal 28-22 °C, acutally measured 20 °C

pH:

activated sludge: 7.49
synthetic waste water: 7.27

Dissolved oxygen:

permanent aeration to keep the dissolved oxygen concentration above 60-70 % saturation and to maintain the sludge flakes in suspension.

Nominal and measured concentrations:

1000 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Type (delete if not applicable): open
- Material, size, fill volume: 500 mL; glass; 500 mL
- Aeration: Yes (permanent)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): triplicates at the beginning of the test and triplicates at the end of the test
- No. of vessels per vehicle control (replicates): no vehicle
- No. of vessels per abiotic control (replicates): -
- Sludge concentration (weight of dry solids per volume): 2.80 g(L (dry sludge concentration) = 1.40 g/L suspended solids in the test vesseks
- Weight of dry solids per volume of reaction mixture per unit of time: 1000 mg test item per liter


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Synthetic waste water according to OECD Guideline 209

OTHER TEST CONDITIONS
- Adjustment of pH: no

Reference substance (positive control):

yes

Remarks:

Copper (II) sulphate pentahydrate

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

From the oxygen depletion the oxygen uptake rates were calculated in mg O2/Lxh, additionally the respiration rates based on the dry sludge concentration were calculated in mg O2/gxh. The inhibition of the oxygen uptake rates of the first test item concentrations in % was calculated in comparison to the oxygen uptake rates of the control.
The test item did not cause inhibiting effects on activated sludge of a municipal seawage treatment plant at the limit test of 1000 mg/L.

Results with reference substance (positive control):

In the reference test the EC50 value for Copper (II) sulphate pentahydrate was 104 mg/L (95 % CI = 101 - 106 mg/L). This is in the recommended range of 53 - 155 mg/L.
The mean specific oxygen uptake rate of control replicates was 20.8 mg O2/gxh (validity criterion >/= 20 mg O2/gxh).
The coefficient of variation of the oxygen uptake rates in the control replicates was 2.9 % (validity criterion <30 %).

Validity criteria fulfilled:

yes

Conclusions:

The NOEC of the test material was >/= 1000 mg/L. There were no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit test item concentration of 1000 mg/L.

Executive summary:

A Respiration Inhibition Test with activated sludge according to OECD Guideline 209 was carried out with the test item. The test activated sludge of the municipal treatment plant. The test was carried out under static conditions with the limit test item concentration 1000 mg/L. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours, and the inhibitory effects of the test and reference item were determined in comparison to the control respiration rates. The mean inhibition of respiration for the test item replicates was -1%.

In order to check the activity of the test system and the test conditions a reference test was carried out with copper(II) sulphate pentahydrate as reference item and the reference toxicity was determined. The EC50 value for the reference item was 104 mg/L. The validity criteria of the test guideline were fulfilled.

The NOEC of the test item is >= 1000 mg/L. The test item caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit test item concentration of 1000 mg/L.

Description of key information

OECD 209: NOEC >= 1000 mg/L

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

A Respiration Inhibition Test with activated sludge according to OECD Guideline 209 was carried out with the test item. The test activated sludge of the municipal treatment plant. The test was carried out under static conditions with the limit test item concentration 1000 mg/L. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours, and the inhibitory effects of the test and reference item were determined in comparison to the control respiration rates. The mean inhibition of respiration for the test item replicates was -1%.

In order to check the activity of the test system and the test conditions a reference test was carried out with copper(II) sulphate pentahydrate as reference item and the reference toxicity was determined. The EC50 value for the reference item was 104 mg/L. The validity criteria of the test guideline were fulfilled.

The NOEC of the test item is >= 1000 mg/L. The test item caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit test item concentration of 1000 mg/L.