5-methyl-1,3-oxazolidin-2-one

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-04-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study according to OECD guideline

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

5-methyl-1,3-oxazolidin-2-one

EC Number:

810-292-9

Cas Number:

1072-70-4

Molecular formula:

C4H7NO2

IUPAC Name:

5-methyl-1,3-oxazolidin-2-one

Details on test material:

- Name of test material (as cited in study report): 5-methyl oxazolidin-2-one
- Physical state: Liquid/colorless, clear
- Analytical purity: 98.0 area-% (GC)
- Lot/batch No.: EWALD-00441
- Expiration date of the lot/batch: 19 Jan 2017
- Stability under test conditions: stable
- Storage condition of test material: Ambient at room temperature
- Water solubility: Completely miscible at room temperature

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Direct addition by initial weight into the test flasks. The test
substance was weighed in the required amounts for the test concentrations directly to the test
vessels.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Age: 1 day
Origin: aeration tank of the wastewater treatment plant of Mannheim, Germany
Collection of the test system: 27 Apr 2015
Arrival in the test facility: 27 Apr 2015
- Preparation of inoculum for exposure: After arrival of the activated sludge suspension in the test facility the suspension was sieved
with a fine woven mesh (mesh size about 1 mm). This suspension was pre-aerated over
night at room temperature. At the next day the sludge suspension was washed once with
drinking water and the suspension was adjusted to 3 g/L Dw.
- Sludge concentration in the test: 1.5 g/L Dw

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

180 min

Test conditions

Test temperature:

23.1 – 23.4 °C

pH:

7,4-8,4

Nominal and measured concentrations:

1000, 500, 250, 125, 62.5 mg/L as nominal concentration based on test substance without correction of purity and blank
control.

Details on test conditions:

TEST SYSTEM
- Test vessel: Glas-beakers (nominal volume 1L)
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 500 mL
- Aeration: the incubation was started by aeration of the test vessels with pressured air.
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- Oxygen concentration during aeration: > 2 mg/L
- Oxygen concentration immediately before measurement: > 7 mg/L
- Duration of the measurement of oxygen consumption: about 8 - 10 min
- Sludge concentration in the test vessel: 1.5 g/L Dw


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: 16 mL/test vessel of 100-fold concentrated OECD medium

OTHER TEST CONDITIONS
- Adjustment of pH: no

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Test concentrations: 1000, 500, 250, 125, 62.5 mg/L

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

180 min

Dose descriptor:

EC10

Effect conc.:

67 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 42.7/103.6

Effect concentrations 2

Duration:

180 min

Dose descriptor:

other: EC20

Effect conc.:

140 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 106.7/192.0

Effect concentrations 3

Duration:

180 min

Dose descriptor:

EC50

Effect conc.:

620 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 500.2/770.3

Effect concentrations 4

Duration:

180 min

Dose descriptor:

other: EC80

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

The EC50 of 3,5-dichlorophenol: 9.7 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The value of effect concentrations of EC10 EC20 EC50 were given with an accuracy of 2 significant digits. The degree of inhibition was evaluated by Probit analysis according to Finney. The results in this study are consistent with all validity criteria and the test is valid according to the guidelines used for this study. One deviation from the study plan and the test guidelines was realized: Exceeding the test temperature range of 20 ± 2 °C with 1.4 °C. An influence to the results of this study can be excluded.