1-ethyl-1-methylpyrrolidinium bromide

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

August 2016 - September 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

under GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Test substance name MEP
Chemical Name N-ethyl-N-methylpyrrolidinium bromide
CAS No. 69227-51-6
Molecular formula C7H16NBr
Formula weight 194.11
Physicochemical property
Appearance Colorless liquid
Solubility in water Soluble in water
Storage and protection
Storage condition 10~30°C
Supplied by
Bromine compounds Ltd.
Batch No. W5-03
Content 65.3%
Effective date 2019-08

Analytical monitoring:

yes

Details on sampling:

The concentrations of the test solutions had been measured at the beginning and the end of the exposure.
When sampling, volume of 15 mL samples was taken out from each test vessels with equal volume of each treated group.

Vehicle:

no

Details on test solutions:

Test solution of Control group: 50 ml test medium were added to the prepared volumetric flask, then made up to 100 ml with alga solution (2×104 cells/ml) and they were mixed and transferred the solutions into each test vessel with six replicates. Finally, cap the test flasks with air-permeable sealing membranes and place them randomly into the shaking illumination incubator.
Test solution of Treated group: 50 ml test substance solution were added to the prepared volumetric flask, then made up to 100 ml with alga solution (2×104 cells/ml) and they were mixed and transferred the solutions into each test vessel with three replicates. Finally, cap the test flasks with air-permeable sealing membranes and place them randomly into the shaking illumination incubator.

Test organisms (species):

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

Details on test organisms:

Test species
Species
Pseudokirchneriella subcapitata
Source
Freshwater Algae Culture Collection of the Institute of Hydrobiology (FACHB-Collection) (Code: FACHB-271)
Breeding generation No.
AC039-20160813-01
Sensitivity
The72h-ErC50 was 2.577 mg/L (study No.: 2016-AE-S01) which can meet the sensitivity requirement. (72h- ErC50=3.38±1.30 mg/L)
Justification for Test Species

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

no

Test temperature:

22.1°C~23.9°C

pH:

8

Salinity:

no

Nominal and measured concentrations:

see table below at: any other information on materials and methods

Details on test conditions:

Duration 72 hours
Lighting 6049~7618 lx
Temperature 22.1oC ~23.9oC
Shaking speed 100 rpm
Photoperiod continuous illumination
Volume 100 mL
Test vessel 250 mL glass conical flask
Pre-culture the alga to the exponential growth under the conditions as the test to adapt alga to test conditions before test starting. The initial cell density was 1×104 cells/ml.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 166.811 - < 370.75 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence level

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 179.006 - < 387.368 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence level

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 20.275 - < 28.591 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks on result:

other: 95% confidence level

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 23.09 - < 32.375 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks on result:

other: 95% confidence level

Details on results:

see attached document on results

Validity criteria fulfilled:

yes

Conclusions:

Under the test conditions in this study, the 72h-ErC50 of test substance MEP on Pseudokirchneriella subcapitata were 248.332 mg/L (Based on the nominal concentration) and 234.049 mg/L (Based on the measured concentration); the 72h-EyC50 of test substance MEP on Pseudokirchneriella subcapitata were 27.382 mg/L (Based on the nominal concentration) and 24.112 mg/L (Based on the measured concentration).

Executive summary:

Objective

To evaluate the acute toxicity effects of the MEP on growth and reproduction of an unicellular green algae (Pseudokirchneriella subcapitata) species, over a 72 hour exposure.

Methods

Based on the results of the preliminary range-finding test, a series of seven concentrations at 4, 8, 16, 32, 64, 128, 256 mg/L with three replicates each group and one control group with six replicates were used for the definitive study to evaluate the acute toxicity of MEP to the green algae. The geometric series is 2.0. The initial cell density was approximately 1×104 cells/ml. The duration of test was 72 hours.

The cell densities of each group were counted with Z2 Beckman Coulter after 24, 48 and 72 hours exposure and the cell condition for one vessel in each exposure group and control were observed under microscope at the end of the exposure. The concentrations of the test substance were measured at 0 and 72 hours of each exposure group.

The percentage of yield and growth rate were calculated at 24h, 48h and 72h, and furthermore the EC50 and its 95% confidence limit were estimated using probit analysis.

Results

Test condition: Temperature: 22.1℃~23.9 ℃; Light intensity: 6049 lx~7618 lx; The pH change of the control group: 0.37.

Observation: No abnormality was observed at the end of the exposure for control and exposure groups.

The concentrations of the test solutions were measured at the start and the end of the exposure. At the start of the exposure, the measured concentrations of test substance remained within 80.0%~101.6% of the nominal concentration, which could be satisfactorily maintained within 80%~120%. At the end of the exposure, the measured concentrations remained within 77.5%~101.6% of the nominal concentration, which cannot be satisfactorily maintained within 80%~120%. But the ratio of measured concentrations between the end and the start of the exposure was 87.3%~106.3%, which can be satisfactorily maintained within 80%~120%. Thus the measured concentrations at the start of the exposure were used to estimate the EC50 and its 95% confidence limit during the study.

72h-EC50 and 95% confidence limits

(unit: mg/L. The concentration was based on the actual concentration from the CoA.):

Nominal concentration

Measured concentration

Based on the growth rate

ErC50 (95% confidence limit)

ErC50 (95% confidence limit)

248.332（179.006~387.368）

234.049（166.811~370.750）

Based on the yield

EyC50 (95% confidence limit)

EyC50 (95% confidence limit)

27.382（23.090~32.375）

24.112（20.275~28.591）

Description of key information

Under the test conditions in this study, the 72h-ErC50 of test substance MEP on Pseudokirchneriella subcapitata were 248.332 mg/L (Based on the nominal concentration) and 234.049 mg/L (Based on the measured concentration); the 72h-EyC50 of test substance MEP on Pseudokirchneriella subcapitata were 27.382 mg/L (Based on the nominal concentration) and 24.112 mg/L (Based on the measured concentration).

Key value for chemical safety assessment

EC50 for freshwater algae:

24 mg/L