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Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
16 to 17 January 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))
Version / remarks:
2010
Deviations:
no
GLP compliance:
yes (incl. certificate)
Details on sampling:
every 15 minutes over a total period of 3 hours
Test organisms (species):
activated sludge, domestic
Test temperature:
19.5-20.1 °C
pH:
The pH was measured on the day prior to the preliminary test in sacrificial beakers (containing test material, sewage feed and deionised water but without sludge inoculum). Values of 7.12, 7.13, 7.04 and 7.04 were recorded for 10, 100, 1000 and (abiotic) 1000mg/l respectively
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol
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
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Key result
Duration:
3 h
Dose descriptor:
other: EC20
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Details on results:
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: none reported
- Effect concentrations exceeding solubility of substance in test medium: no effects found
- Adsorption (e.g. of test material to the walls of the test container): none reported
- Blank controls oxygen uptake rate: 24.00 mg O2/g dry weight of activated sludge/hour
- Coefficient of variation of oxygen uptake rate in control replicates: 5.08%


 
Results with reference substance (positive control):
- Results with reference substance valid. yes
- Relevant effect levels: 3,5-DCP EC20 = 0.87 mg/L, EC50 = 3.23 mg/L
Reported statistics and error estimates:
The inhibition of respiration was calculated compared to the controls. It was not possible to determine confidence limits for the eC20 and EC 50 values. NOEC was determined following Shapiro-Wilk’s Test which indicated normal distribution and F-Test

No statistically significant toxic effect occured at a concentration of 1000 mg/L:

Treatment and Concentration (mg/L)

Percentage inhibition (%)

10 (1 replicate)

2

100 (1 replicate)

2

1000 (3 replicates, averaged)

6

 

Validity criteria fulfilled:
yes
Conclusions:
There was less than 10% inhibition at 1000mg/L in the limit test with 3 replicates. Hence, in accordance with the OECD test guideline no. 209, no further testing was necessary. The NOEC (3h) was determined to be 1000 mg/L, and the EC50 (3h) was > 1000 mg/L
Executive summary:

The study was conducted according to the current OECD test guideline 209. The Reaction mass of Cucurbit[6]uril, Cucurbit[7]uril and Cucurbit[8]uril exhibited minimal respiration inhibition at 1000mg/L. The Reaction mass of Cucurbit[6]uril, Cucurbit[7]uril and Cucurbit[8]uril also demonstrated no abiotic response.

The 3 hour EC50 of Reaction mass of Cucurbit[6]uril, Cucurbit[7]uril and Cucurbit[8]uril to activated sludge respiration inhibition was calculated as >1000 mg/L (using linear interpolation) during the preliminary study.

The NOEC for Reaction mass of Cucurbit[6]uril, Cucurbit[7]uril and Cucurbit[8]uril was determined to be 1000 mg/L using direct observation.

Description of key information

No toxicity was found at the limit dose of 1000 mg/L in an activated sludge respiratory inhibition test performed in accordance with OECD test guideline no. 209.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
1 mg/L

Additional information