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

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-09-21 - 2015-09-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

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 201 (Alga, Growth 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 substance: 5-methyl oxazolidin-2-one
- Test substance No.: 15/0112-1
- CAS No.: 1072-70-4
- purity: 98.0 area-% (GC)
- physical state / appearance: liquid / colorless, clear

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Sampling was performed at the start of the exposure (0 h) from the inoculated replicate 7 of the concentration and the control.
At the end of the exposure (72 h) samples were taken from the combined inoculated replicates of the test concentrations and of the combined inoculated control group replicates.

Test solutions

Details on test solutions:

An inoculum culture in exponential growth phase was prepared with an aliquot of the stock algal culture added to sterile test media to provide an initial cell density of 0.5 x 104 cells/mL. The inoculum culture is incubated under test conditions for 4 days prior to test initiation. The increase in biomass is verified to ensure that growth is within the normal range and algal cells are examined microscopically for normal morphology prior to use for test inoculation. Inoculum culture cell density (4 days growth): 242 x 104 cells/mL (484 fold increase) Inoculum culture morphology: normal and healthy.

The test substance container was shaken to ensure homogeneity before removal for weighing. The test substance was weighed in and made up with OECD medium to reach concentrations of 111% of the nominal concentration to compensate for the dilution by the later addition of inoculum.
The stock test solution (133.2 mg/L) was prepared by weighing 266.86 mg test substance and diluting it in 2L test water. The mixture was then stirred vigorously for about 10 minutes on a magnetic stir plate. To reach the correct nominal concentration (120 mg/L) at test start, 10 mL of inoculum culture was added to 90 mL of the stock test solution. The stock test solution appeared colorless and clear.

Test organisms

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Details on test organisms:

-Test species and strain: Pseudokirchneriella subcapitata KORCHIKOV (SAG 61.81)
- Age (on study day 0): A stock algal culture is maintained continuously at the test facility. Before the exposure an inoculum culture is prepared
from the stock culture and incubated for 4 days at 21 – 24 °C (max. temperature difference 2 °C). After this time, the inoculum
culture is in exponential growth phase and can be used to initiate the test (study day 0).
- Supplier: Collection of algal cultures in University of Göttingen/Germany

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

23.5 - 23.7°C

pH:

7.9 - 8.8

Nominal and measured concentrations:

nominal concentrations: control, 120 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks (nominal volume 250 mL) plugged with gas permeable silicone sponge caps
- Test volume: 100 mL
- Initial cells density: 0.5 x 104 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6
- No. of vessel per test group for initial concetration control analysis only: 1
- No. of vessel additional uninoculated (without algae) replicate per test group for background fluorescence correction and to determine the
influence of the test design on test substance stability: 1


GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16:8
- Light intensity and quality: Average 5979 lux (within ±15% variability) at a wave length of 400 - 700 nm

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 120 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 120 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

ErC50=0.92-1.46mg/L after 72 hours

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Executive summary:

In a 72-hour algal growth study, cultures of Pseudokirchneriella subcapitata were exposed to 5-methyl oxazolidin-2-one at nominal concentrations of 0 (control) and 120 mg/L under static conditions for in accordance with the OECD 201 guideline. The water pH, temperature and lighting intensity were all maintained within acceptable guideline specifications. The following statistical effect concentrations were obtained after 72 hours of exposure: ErC50>120 mg/L, NOErC >=120mg/L.