N,N-bis(1-methylethyl)formamide

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From February 02, 2021 to February 08, 2021

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

28 July 2011

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch number: M-O303190723301F
Purity: 99.68%

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 100 mg/L
- Sampling method: Samples were taken for analysis from the freshly prepared solutions at 0 hour and the old solutions at 72 hours.
- Sample storage conditions before analysis:

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A solution of test item at a nominal concentration of 100 mg/L was prepared with OECD alga growth medium. 0.1002 g of test item was weighed and dissolved in 1000 mL of growth medium directly. After the test item was dissolved completely, the solution was used for exposure.
- Differential loading: The biomass of the pre-cultured alga inoculums was counted and the mean concentration was 2.09×106 cell/mL. 2.390 mL of alga inoculum culture was added into the flask to make the initial biomass to be 5×103 cell/mL in the volume of 1000 mL.
- Controls: The control solution was 1000 mL growth medium inoculated with the same volume of alga inoculum culture and without test item.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: freshwater alga
- Strain: Pseudokirchneriella subcapitata
- Source (laboratory, culture collection): The stock alga was originally introduced from CTI Chemical Safety Evaluation Research Center (SUZHOU) CO., LTD
- Age of inoculum (at test initiation): The age of preculture at inoculation of the definitive test was four days.
- Method of cultivation:

ACCLIMATION
- Acclimation period: four days
- Culturing media and conditions (same as test or not): same
- Any deformed or abnormal cells observed:

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

21-24 oC

Nominal and measured concentrations:

100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL glass conical flasks
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: 100 mL test solution
- Aeration: All test flasks were capped with air-permeable membrane.
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate): no
- Initial cells density: 5×103 cell/mL
- Control end cells density: 5.15×105 cell/mL
- No. of organisms per vessel:
- No. of vessels per concentration (replicates): 6 replicates
- No. of vessels per control (replicates): 6 replicates
- No. of vessels per vehicle control (replicates):

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: The continuous and uniform light was used
- Light intensity and quality: the light intensity was 4440-8880 Lux for cool white light.
- Salinity (for marine algae):

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: cell counting and percent inhibition in average specific growth rate (Ir) and percent inhibition of yield (Iy)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations: 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study:

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (3,5-DCP) as reference item was tested for EC50 as a means of assuring that the test conditions are reliable twice a year in the laboratory.

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Details on results:

During the 72-hour test duration, there was no abnormal appearance of the algae observed in control replicates and replicates of each test group.
After 72 hours exposure, there was no significant inhibition of algae growth rates and yield at 100 mg/L. There was no significant difference in algae growth rate and growth yield between the control group and the test group of 100 mg/L (p>0.05, t-test).

The results showed that for the test solution of 100 mg/L, the determined concentration in fresh media was 102.03 mg/L. The determined concentration in old media was 104.45 mg/L. The overall mean determined concentration was 103.24 mg/L, which was 103.24% of nominal concentration.

Results with reference substance (positive control):

72 hour EyC50 of 3,5-DCP to Pseudokirchneriella subcapitata was 0.82 mg/L with the 95% confidence limits 0.65 ~ 1.0 mg/L and 72 hour ErC50 was 1.4 mg/L with the 95% confidence limits 0.97 ~ 2.1 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

The 72-hour effect concentration of average specific growth rate (ErC50) of and yield (EyC50) of the test item to Pseudokirchneriella subcapitata were greater than 100 mg/L. The NOEC for growth rate and yield are both 100 mg/L.

Executive summary:

An alga (Pseudokirchneriella subcapitata) growth inhibition study of the test item was conducted over a 72-hour exposure period in a static system, according to OECD Guideline 201 under GLP.

The 72-hour effect concentration of average specific growth rate (ErC50) of and yield (EyC50) of the test item to Pseudokirchneriella subcapitata were greater than 100 mg/L. The NOEC for growth rate and yield are both 100 mg/L.

Description of key information

An alga (Pseudokirchneriella subcapitata) growth inhibition study of the test item was conducted over a 72-hour exposure period in a static system, according to OECD Guideline 201 under GLP.

The 72-hour effect concentration of average specific growth rate (ErC50) of and yield (EyC50) of the test item to Pseudokirchneriella subcapitata were greater than 100 mg/L. The NOEC for growth rate and yield are both 100 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

100 mg/L