Allyl heptanoate

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:

2022-01-31 to 2022-02-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2011

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Sampling at test start (0 hours), at 24 hours, at 48 hour and at the end of exposure (72h)

Vehicle:

no

Details on test solutions:

A stock solution with a nominal loading of 10.0 mg test item/L was freshly prepared with dilution water. The dispersion
was stirred for 2 hours in a closed system (1100 rpm, room temperature) until the solution was visually clear.

Out of the stock solution 5 concentrations were tested in a geometrical series with a dilution factor of √10:
0.100 - 0.316 - 1.00 - 3.16 - 10.0 mg/L

The dilution levels were based on the results of a preliminary range finding test (non-GLP, closed bottles without headspace).

Test organisms (species):

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

Details on test organisms:

Origin: Culture Collection of Algae and Protozoa (CCAP)
SAMS Research Services Ltd
Dunstaffnage Marine Laboratory
Dunbeg, OBAN; Argyll PA37 1QA; Scotland, UK

Cultivation at test facility: Fresh stocks are prepared every month on Z-Agar. Light intensity amounts 2567 – 5130 lux for 24 hours per day.
Culture medium: Nutrient medium Z according to LÜTTGE et al. (1994)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

40 mg CaCO3/L

Test temperature:

23.5 - 24°C (mean value: 23.8°C)

pH:

8.03 (0h) to 10 (72h)

Nominal and measured concentrations:

Nominal concentrations: 10, 3.16, 1, 0.316, 0.1 mg/L
Measured initial concentrations: 9.48, 2.71, 0.848, 0.267, 0.0787 mg/L
The measured concentrations decreased with time leading to concentrations below the limit of determination within 48 hours. As the decrease in concentration of the test substance is not accompanied by a decrease in growth inhibition, all endpoints are given based on initial measured
concentrations.

Details on test conditions:

TEST SYSTEM
- Test container: Sterile headspace flasks, volume: 59 mL, with aluminium tops with PTFE seals
- Type (delete if not applicable): closed, without headspace
- Test volume: 59 mL

- Initial cell density: 6864 cells/mL
- Replicates: Three replicates per concentration and six for the control Separate replicates for each measuring time were prepared.

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Light intensity (target) mean value: 5114 lux, range of measued values: 4530 - 5618 lux
- Light regime: 24 hours/day light

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- The cell density was measured daily via Chlorophyll afluorescence, excitation at 436 nm, emission at 685 nm. Dilution water was used as a background signal. No self-fluorescence was observed at the start of the preliminary range finding test at the concentration of 10.0 mg/L.
- Microscopic evaluation: Microscopic evaluation of the cells at the start and the end of the incubation period was carried out. The cells were checked for unusual cell shapes, colour differences, differences in chloroplast morphology, flocculation, adherence of algae to test containers and agglutination of algae cells.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: root 10
- Range finding study: yes
- Test concentrations: 10, 1, 0.1 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

Potassium dichromate was tested as reference item.

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.94 mg/L

95% CI:

>= 1.29 - <= 2.31

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.29 mg/L

95% CI:

>= 0.887 - <= 1.98

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.848 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.37 mg/L

95% CI:

>= 1.09 - <= 1.96

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

yield

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.02 mg/L

95% CI:

>= 0.884 - <= 1.66

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.848 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

yield

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

- Results with reference substance valid? yes
- ErC50: 1.09 (0.944 - 1.25)

Validity criteria fulfilled:

yes

Conclusions:

The test substance was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (based on initial
measured test item concentration):
The EC10-values with 95% confidence intervals for inhibition of growth rate (ErC10) after 72 hours were 1.29 (0.887 – 1.98) mg/L.
The EC50-values with 95% confidence intervals for inhibition of growth rate (ErC50) after 72 hours were 1.94 (1.29 – 2.31) mg/L.
The NOEC-values for both inhibition of growth rate and yield after 72 hours were 0.848 mg/L.
The measured concentrations decreased with time leading to concentrations below the limit of determination within 48 hours. As the decrease in concentration of the test substance is not accompanied by a decrease in growth inhibition, all endpoints are given based on initial measured
concentrations.

Executive summary:

A valid study according to OECD 201 over 72h under static conditions resulted in a 72-hour ErC50 value of 1.94 mg/L. The corresponding 72h- ErC10 value is reported as  1.29 mg/L.

Due to the volatility of the test substance the test was done in a closed system without headspace.

Description of key information

A guideline study (OECD 201) is available for this endpoint resulting in an ErC50 (72 h) of 1.94 mg/L and an ErC10 (72 h) of 1.29 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

1.94 mg/L

EC10 or NOEC for freshwater algae:

1.29 mg/L

Additional information

Experimental data on the toxicity of allyl heptanoate to freshwater algae Pseudokirchneriella subcapitata is available. A valid study according to OECD 201 over 72h under static conditions resulted in a 72-hour ErC50 value of 1.94 mg/L. The corresponding 72h- ErC10 value is reported as  1.29 mg/L.

Due to the volatility of the test substance the test was done in a closed system without headspace.