4-ethoxy-2,3-difluoro-4'-propyl-1,1'-biphenyl

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:

2017-06-22 to 2017-06-23

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))

Version / remarks:

July, 2010

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Test item was weighted directly in Erlenmeyer flasks and stirred overnight with test medium.
- Controls: negative control: test medium without substance addition; positive control: reference substance Copper (II) sulphate pentahydrate p.a. (concentrations 58, 100 and 180 mg/L)
- Test concentration separation factor: A limit test was performed.
- Evidence of undissolved material: No

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture: not applicable
- Name and location of sewage treatment plant where inoculum was collected: Municipal sewage treatment plant of 31137 Hildesheim, Germany
- Method of cultivation: A fresh sample was used.
- Pretreatment: 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.
- Initial biomass concentration: Dry sludge concentration was 2.94 g/L (corresponding to 1.47 g/L suspended solids in the test vessels).

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Post exposure observation period:

not applicable

Hardness:

not specified

Test temperature:

20.9 °C

pH:

activated sludge: 7.60
synthetic waste water: 7.18

Dissolved oxygen:

determined at start of measurement:
control: 7.13 - 9.56 mg O2/L
reference item: 5.72 - 8.02 mg O2/L
test item: 6.85, 7.14, and 6.72 mg O2/L

Salinity:

not applicable

Conductivity:

not specified

Nominal and measured concentrations:

1000 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 mL Erlenmeyer flasks, DIN 12380
- Type: open
- Material, headspace, fill volume: glass, not specified, 500 mL
- Aeration: Permanent, to keep the dissolved oxygen concentration above 60 - 70 % saturation and to maintain the sludge flakes in suspension.
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- Sludge concentration (weight of dry solids per volume): 2.94 g/L (corresponding to 1.47 g/L suspended solids in the test vessels)
- Nutrients provided for bacteria: Synthetic wastewater according to OECD-Guideline 209 was used as nutrient solution.
- Nitrification inhibitor used: none

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Synthetic waste water (16 mL) according to OECD-Guideline 209 and Demineralised water (to fill up to 250 mL after addition of test or reference item), together with Inoculum (250 mL) were used in preparation of test/reference item solution.

OTHER TEST CONDITIONS
- Adjustment of pH: not performed
- Photoperiod: not specified
- Light intensity: not specified
- Details on termination of incubation: not specified

EFFECT PARAMETERS MEASURED: The oxygen concentration in the measurement chamber was measured by the oximeter by optical read-out of the sensor spots at least every 5 seconds.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: Limit test was performed.
Range finding study
- Test concentrations: 10, 100 and 1000 mg/L
- Results used to determine the conditions for the definitive study: Based on the results of the preliminary test it could concluded that the heterotrophic respiration as well as the nitrification are not inhibited. Therefore, the definitive study was carried out as a limit test using 1000 mg/L.

Reference substance (positive control):

yes

Remarks:

Copper (II) sulphate pentahydrate p.a.

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:

other: No inhibiting effects were observed up to the limit concentration.

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No such effects were observed.
- Effect concentrations exceeding solubility of substance in test medium: No.
- Adsorption (e.g. of test material to the walls of the test container): No.
- Blank controls oxygen uptake rate: 35.4 +/- 1.28 mg O2/(L*h)
- Coefficient of variation of oxygen uptake rate in control replicates: 3.62 %

Results with reference substance (positive control):

- Results with reference substance valid: Yes.
- Relevant effect levels: EC50 = 96 mg/L

Reported statistics and error estimates:

The NOEC was determined by calculation of statistical significance of the inhibition of respiration in comparison to the control. One Way Analysis of Variance (ANOVA) was used for NOEC calculation. When running a One Way Analysis of Variance a Normality test and an Equal Variance test were done first. P-value for both tests was 0.05. The α-value (acceptable probability of incorrectly concluding that there is a difference) is α=0.05. No statistically significant inhibiting effect was determined for the test item (P = 0.063), ANOVA.

Validity criteria fulfilled:

yes

Conclusions:

The test material caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit test item concentration of 1000 mg/L and the NOEC was determined to be ≥ 1000 mg/L.

Executive summary:

A Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 (2010) was carried out with the test item. The test system was activated sludge of the municipal treatment plant of 31137 Hildesheim, Germany. 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 6%. 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 96.0 mg/L. The validity criteria of the test guideline were fulfilled. The test material caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit test item concentration of 1000 mg/L and the NOEC was determined to be ≥ 1000 mg/L.

Description of key information

The test material caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit test item concentration of 1000 mg/L and the NOEC was determined to be ≥ 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 No. 209 (2010) was carried out with the test item. The test system was activated sludge of the municipal treatment plant of 31137 Hildesheim, Germany. 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 6 %. 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 96.0 mg/L. The validity criteria of the test guideline were fulfilled. The test material caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit test item concentration of 1000 mg/L and the NOEC was determined to be ≥ 1000 mg/L.