Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 June 2018 - 09 October 2018
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
Based on the results of the preliminary test it was concluded that the heterotrophic respiration as well as the nitrification are not inhibited. Therefore, the definitive study was carried out with the concentration of 1000 mg/L in 3 replicates (limit test to determine the NOEC). The concentration was weighed out on bent object slides and were transferred to laboratory bottles. The bottles were closed immediately.
Triplicates of the control without test item were included at the beginning and at the end of the test.

Test organisms

Test organisms (species):
activated sludge
Details on inoculum:
Test System Activated sludge
Origin Municipal sewage treatment plant of 31137 Hildesheim, Germany
Reason for the selection Non-adapted activated sludge from the sewage plant at Hildesheim is well suited as it receives predominantly municipal sewage
and hardly any industrial chemical waste.
Pre-treatment 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.
Date of receipt 2018-07-16
Dry sludge concentration 2.91 g/L (corresponding to 1.46 g/L suspended solids in the test vessels)

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
3 h

Test conditions

Test temperature:
20,9 °C
pH:
7,21 - 7,57
Reference substance (positive control):
yes
Remarks:
Copper (II) sulphate pentahydrate p.a. CAS 7758-99-8 Merck Lot AM0934890

Results and discussion

Effect concentrations
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:
Oxygen Uptake Rates and Inhibition of the Respiration of the Test Item Concentration

Test Item Concentration Repl. Oxygen
Concentration* Oxygen Uptake Rate R Inhibition Mean Inhibition
[mg/L] [mg O2/L] [mg O2/(L×h)] [%] [%]
1000 1 6.50 20.9 2 9
2 6.39 19.0 11
3 5.96 1 8.4 14

Oxygen Uptake Rates, Inhibition of the Respiration of Control Replicates
Repl. Oxygen
Concentration* Oxygen Uptake Rate R Specific Respiration Rate Rs
[mg O2/L] [mg O2/(L×h)] [mg O2/g×h]
Control 1 6.87 20.8 14.2
2 7.15 19.7 13.5
3 6.60 18.7 12.8
4 7.22 23.7 16.2
5 6.93 23.1 15.8
6 6.76 21.9 15.0
Mean value 21.3 14.6
Standard deviation 1.78
CV [%] 8.36

*) determined at start of the measurement
Repl. = Replicate
CV = Coefficient of variation


Test item Concentration
[mg/L]
NOEC* ≥ 1000
*) No statistically significant inhibiting effect (P = 0.180), ANOVA
Results with reference substance (positive control):
Oxygen Uptake Rates and Inhibition of the Respiration of the Reference Item Concentrations

Reference Item Repl. Oxygen
Concentration Concentration* Oxygen Uptake Rate R Inhibition Mean Inhibition
[mg/L] [mg O2/L] [mg O2/(L×h)] [%] [%]
58 1 7.77 15.4 28 30
2 7.79 15.6 27
3 7.37 14.1 34
100 1 7.78 10.9 49 50
2 7.68 11.0 48
3 7.21 10.2 52
180 1 8.09 4.2 80 81
2 8.09 3.9 82
3 7.59 3.9 82
*) determined at start of the measurement
Repl. = Replicate

In the reference test the EC50-value for copper (II) sulphate pentahydrate was determined with:

EC50 = 93.9 mg/L
95 % Confidence Interval = 88.1 – 99.7 mg/L

This is in the recommended range of validity of 53 - 155 mg/L.

Reported statistics and error estimates:
11 Statistical Analysis (NOEC)

One Way Analysis of Variance

Data source: 180607HS / BBR18277

Normality Test (Shapiro-Wilk) Passed (P = 0.862)

Equal Variance Test: Passed (P = 0.662)

Group Name N Missing Mean Std Dev SEM
Control 6 0 21.317 1.946 0.794
1000 mg/L 3 0 19.433 1.305 0.754

Source of Variation DF SS MS F P
Between Groups 1 7.094 7.094 2.223 0.180
Residual 7 22.335 3.191
Total 8 29.429

The differences in the mean values among the treatment groups are not great enough to exclude the possibility that the difference is due to random sampling variability; there is not a statistically significant difference (P = 0.180).

Power of performed test with alpha = 0.050: 0.154

The power of the performed test (0.154) is below the desired power of 0.800.
Less than desired power indicates you are less likely to detect a difference when one actually exists. Negative results should be interpreted cautiously.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The NOEC of the test item Dihydro-3,5-bis(1-methyldecyl)-1H,3H,5H-Oxazolo[3,4-c]oxazole is ≥ 1000 mg/L.

Dihydro-3,5-bis(1-methyldecyl)-1H,3H,5H-Oxazolo[3,4-c]oxazole caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit test item concentration of 1000 mg/L.
Executive summary:

The NOEC of the test item Dihydro-3,5-bis(1-methyldecyl)-1H,3H,5H-Oxazolo[3,4-c]oxazole is ≥ 1000 mg/L.

Dihydro-3,5-bis(1-methyldecyl)-1H,3H,5H-Oxazolo[3,4-c]oxazole caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit test item concentration of 1000 mg/L.