Vinyl ethylene carbonate

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:

From September 16 to 18, 2021

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))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Lot number: 10121040902
Purity: 99.92%

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: To prepare test item mixtures, the test item was directly weighed into the test vessel and distilled water was added.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture:
- Name and location of sewage treatment plant where inoculum was collected: A fresh sample of activated sludge was collected from the aeration tank of Shenyang North Sewage Treatment Plant 1 day before the test was started.
- Method of cultivation: The activated sludge was fed with the synthetic sewage feed (50 mL synthetic sewage feed/L activated sludge) and continuously aerated at the test temperature (20.2~21.0°C) overnight prior to use in the test.
- Preparation of inoculum for exposure:
- Pretreatment: On the day of activated sludge collection, coarse particles were removed by settling for 15 minutes and by decanting the upper layer of finer solids. The sludge was washed as follows: the sludge was first centrifuged for 5 minutes at ca. 2500 rpm to produce a clear supernatant and pellet of sewage solids. The supernatant liquid was discarded and the sludge was re-suspended in chlorine-free tap water by shaking, and the wash-water was removed by re-centrifuging and discarding again. After re-suspension of the sludge pellet in chlorine-free tap water, the solids dry weight was determined by drying 5 replicates of 10 ml suspended sludge at 105oC for 1.5 hours.
- Initial biomass concentration: 3 g/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20±2°C

pH:

8.14-8.26

Dissolved oxygen:

2.84-8.38 mg/L

Nominal and measured concentrations:

Nominal concentrations: 10, 100, 300 and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: flask
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 500 mL
- Aeration: clean oil-free air, flow rate 0.5~1 L/min
- No. of vessels per concentration (replicates): one for 10, 100, 300 mg/L, three for 1000 mg/L
- No. of vessels per control (replicates): one
- No. of vessels per abiotic control (replicates): one
- Sludge concentration (weight of dry solids per volume): 3 g/L

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The concentration of dissolved oxygen was continuously measured and recorded for 10 minutes.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

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

Details on results:

In preliminary test, the specific oxygen uptake rate of the blank controls (without the test item or reference item) was 21.3 mg/(g·h SS) oxygen. The coefficient of variation of oxygen uptake rate in control replicates was 4.1% at the end of the test. The validity criteria have therefore been satisfied.
Based on the preliminary test results of the test item test, there was slight oxygen uptake in the abiotic control. In the test item mixture, the average percentage inhibition was 8.0% at the concentration of 1000 mg/L and the test item had slight inhibition effect in 1000 mg/L.
Due to the absence of significant inhibition of oxygen consumption by the test item in a preliminary test, a definitive test is unnecessary.

Results with reference substance (positive control):

The EC50 (3 hours) of 3,5-dichlorophenol for total respiration is 6.9 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

The EC50 (3 hours) of the test item, VEC, for total respiration of activated sludge was greater than 1000 mg/L.

Executive summary:

The study was conducted to determine the inhibition effect of VEC on micro-organisms from activated sludge (largely bacteria) by measuring their total respiration rate, according to OECD Guideline 209 under GLP. The contact time for exposure was 3 hours.

Based on the preliminary test results of the test item test, there was slight oxygen uptake in the abiotic control. In the test item mixture, the average percentage inhibition was 8.0% at the concentration of 1000 mg/L and the test item had slight inhibition effect in 1000 mg/L.

Due to the absence of significant inhibition of oxygen consumption by the test item in a preliminary test, a definitive test is unnecessary.

Therefore, the EC₅₀ (3 hours) of the test item, VEC, for total respiration of activated sludge was greater than 1000 mg/L under the conditions of the study.

Description of key information

The EC₅₀ (3 hours) of the test item, VEC, for total respiration of activated sludge was greater than 1000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

The study was conducted to determine the inhibition effect of VEC on micro-organisms from activated sludge (largely bacteria) by measuring their total respiration rate, according to OECD Guideline 209 under GLP. The contact time for exposure was 3 hours.

Based on the preliminary test results of the test item test, there was slight oxygen uptake in the abiotic control. In the test item mixture, the average percentage inhibition was 8.0% at the concentration of 1000 mg/L and the test item had slight inhibition effect in 1000 mg/L.

Due to the absence of significant inhibition of oxygen consumption by the test item in a preliminary test, a definitive test is unnecessary.

Therefore, the EC₅₀ (3 hours) of the test item, VEC, for total respiration of activated sludge was greater than 1000 mg/L under the conditions of the study.