N-benzylprop-2-enamide

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:

30 October 2007 to 28 November 2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Qualifier:

equivalent or similar to guideline

Guideline:

ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)

Principles of method if other than guideline:

the exposure duration was 48 hours, while the guidelne prefers a 72 hour exposure

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 100 mg/L (vessel without algae), 0,10, 18, 32, 56 and 100 mg/L at t=0, t=24 and t=48 h
- Sampling method: 1.5 mL samples
- Sample storage conditions before analysis: in freezer

Vehicle:

yes

Remarks:

water

Details on test solutions:

Solutions were ultrasonicated for 10 minutes followed by magnetic stirring during 18 minutes. The solutions were clear and colorless

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: NIVA CL1
- Source: in-house laboratory culture
- Age of inoculum (at test initiation): pre-cultured for 3 days
- Method of cultivation: cutured in M1 medium; pre-culture and test in M2 medium (AAP according to the OECD guideline)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Remarks on exposure duration:

exposure duration deviates from the preferred duration of 72 hours

Hardness:

24 mg/L as CaCO3

Test temperature:

21.9-23.7 ˚C

pH:

7.9-8.2

Nominal and measured concentrations:

nominal 0,10, 18, 32, 56 and 100mg/L
measured concentrations were 98-109% of nominal.

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL, glass
- Type: open
- Fill volume: 50 mL
- Initial cells density: 1.0E04 cells/mL
- Control end cells density: 55.8E04 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: AAP medium according to OECD 201

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Photoperiod: continuous light
- Light intensity and quality: TLD lamps 86-92 µE.m-2.s-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: initial counting chamber (under microscope); thereafter at t=24 and t=48 h with spectrophotometer at 720 nm
- Chlorophyll measurement: none
- Other: any abnormal appearance of the algae at test end

TEST CONCENTRATIONS
- Range finding study: at control, 0.1,1.0,10 and 100 mg/L during 48 hours
- Results used to determine the conditions for the definitive study: cell count at 48 h: 53.4, 52.4, 50.6, 48.7 and 1.4* E04 cells/L at control, 0.1,1.0,10 and 100 mg/L

Reference substance (positive control):

yes

Remarks:

Potassium dichromate at 0.18 to 3.2 mg/L during 72 hours

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

58 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

30 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

< 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: see remarks

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

< 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

At 10 and 18 mg/L growth rate reduction was <10% over the 48 h study period. This could be considered a biologically irrelevant, But as during the first 24 hous the growth rate reduction was 1.6-3.6% and during the second 24 hours 8.1-10.5%, it can be assumed that when extending the test up to 72 hours would lead a growth rate decrease > 10%. Therefore the value of the NOEC is set at <10 mg/L.
A similar increase of growth rate reduction with time was observed at all tested concentrations

Results with reference substance (positive control):

EC50 growth rate 2.1 mg/L
EC50 biomass 0.85 mg/L

Reported statistics and error estimates:

All reported reduction of growth rate and inhibition of biomass were statistically significant in at least one of the statistical methods applied (Bonferroni t-test, Tuckey method)
mean coefficient of variation for section-by-section specific growth rates in the control cultures was < 35% (ANOVA)

Validity criteria fulfilled:

yes

Conclusions:

The 48-h EC50 for growth rate is 58 mg/L
The NOEC for growth rate is < 10 mg/L

Executive summary:

In a test according to OECD 201, green algae were exposed during 48 hours to 0, 10, 18, 32, 56 and 100 mg/L of the test substance. There were statistically significant effects on growth rate and biomass for all tested concentrations. Reduction of growth rate was shown to increase with increasing study duration.

The EC50 for growth rate is 58 mg/L and for biomass 30 mg/L. The NOEC is < 10 mg/L.

Description of key information

In a test according to OECD 201, green algae were exposed during 48 hours to 0, 10, 18, 32, 56 and 100 mg/L of the test substance. There were statistically significant effects on growth rate and biomass for all tested concentrations. Reduction of growth rate was shown to increase with increasing study duration.

The EC50 for growth rate is 58 mg/L and for biomass 30 mg/L. The NOEC is < 10 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

58 mg/L