1,3-dimethyl-3-phenylbutyl acetate

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:

14 September 2015 to 18 September 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Test concentrations and control were analytically verified at 0 and 72 hours.
For the test item analysis after 72 hours, separate samples with algae were prepared at the beginning of exposure and incubated under test conditions.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: 80 mg/L test item in water was prepared one day prior to the start of exposure. This stock solution was stirred for 24 hours at 1100 rpm at room temperature. This was used as the highest loading rate in the test, and further loading rates were prepared by dilution.
- Controls: dilution water without test item
- Test concentrations: Nominal concentration: 2.048, 5.12, 12.8, 32.0, 80.0 mg/L

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Unicellular green algae
- Strain: HINDÄK, SAG 61.81
- Source:Sammlung von Algenkulturen (SAG) Pflanzenphysiologisches Institut der Universität Göttingen Nikolausberger Weg 18, D-37073 Göttingen

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

None

Hardness:

0.24 mmol Ca+Mg/L

Test temperature:

21.5-22.0°C

pH:

8.09-9.24

Dissolved oxygen:

Not reported

Salinity:

Not reported

Nominal and measured concentrations:

Nominal concentration: 2.048, 5.12, 12.8, 32.0, 80.0 mg/L.
The measured concentrations of the test item during the exposure interval were in the range between 85 and 91 % (0 hours) and 80 to 93 % (72 hours) of the nominal value. Therefore, all effect values are given based on the nominal concentrations of the test item.

Details on test conditions:

TEST SYSTEM
- Test vessel: Sterile Erlenmeyer flasks with aluminium tops with PFTE seals
- Type: closed
- Material, size, headspace, fill volume: Glass, 119 mL, no headspace
- Initial cells density: 6153 cell/mL
- Control end cells density: 515067

GROWTH MEDIUM
- Standard medium used: no
- Detailed composition if non-standard medium was used: Nutrient medium Z according to Lüttge et al. (1994)

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: No
- Photoperiod: 24 hours /day light
- Light Intensity: 60 - 120 uE /m2 s

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Chlorophyll a- fluorescence, excitation at 436 nm, emission at 685 nm

Reference substance (positive control):

yes

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2.048 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

5.12 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

6.21 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: lower 95% CL: <2.048 upper 95% CL: 9.50

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

11.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: lower 95% CL: 8.43 upper 95% CL: 12.7

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2.048 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

5.12 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

3.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Remarks on result:

other: lower 95% CL:<2.048 upper limit 95% CL:4.38

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

7.04 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Remarks on result:

other: lower 95% CL: 6.29 upper 95% CL: 8.25

Results with reference substance (positive control):

EC50 with headspace (Growth inhibition) = 0.613 (95% confidence interval 0.589-0.638)
EC50 without headspace (Growth inhibition) = 0.0.774 (95% confidence interval 0.711-1.08)
EC50 with headspace (Yield) = 0.281 (95% confidence interval 0.234-0.314)
EC50 without headspace (Yield) = 0.502 (95% confidence interval 0.400-0.583)

Validity criteria fulfilled:

yes

Remarks:

Increase in cell growth in controls: 84-fold; Mean coefficient of variation for section by section specific growth rate in controls: 33%; Coefficient of variation in average specific growth rate in controls: 1.14%

Conclusions:

The EC50-values for inhibition of growth rate and yield after 72 hours were 11.4 mg/L and 7.04 mg/L, respectively. The EC10-values for inhibition of growth rate and yield after 72 hours were 6.21 mg/L and 3.40 mg/L, respectively. The NOEC-values for inhibition of both growth rate and yield after 72 hours was 2.048 mg/L.

Executive summary:

This study is GLP compliant and follows OECD guideline 201 and EU method C.3. Therefore, it has been assigned a reliability score of 1 (reliable without restrictions). Test solutions were prepared by first preparing a stock solution at a nominal concentration of 80 mg/L, which was stirred for 24 hours at 1100 rpm. This was used as the highest loading rate in the test, and further loading rates were prepared by dilution. Analytical verification of test concentrations was conducted at 0 and 72 hours, and results are based on nominal concentrations. The test item was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (based on nominal test item concentrations): The EC50-values for inhibition of growth rate and yield after 72 hours were 11.4 mg/L and 7.04 mg/L, respectively. The EC10-values for inhibition of growth rate and yield after 72 hours were 6.21 mg/L and 3.40 mg/L, respectively. The NOEC-values for inhibition of both growth rate and yield after 72 hours was 2.048 mg/L.

Description of key information

The test item was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (based on nominal test item concentrations): The EC50-values for inhibition of growth rate and yield were 11.4 mg/L and 7.04 mg/L, respectively. The EC10-values for inhibition of growth rate and yield were 6.21 mg/L and 3.40 mg/L, respectively. The NOEC-values for inhibition of both growth rate and yield were 2.048 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

11.4 mg/L

EC10 or NOEC for freshwater algae:

2.048 mg/L

Additional information

This study is GLP compliant and follows OECD guideline 201 and EU method C.3. Therefore, it has been assigned a reliability score of 1 (reliable without restrictions). Test solutions were prepared by first preparing a stock solution at a nominal concentration of 80 mg/L, which was stirred for 24 hours at 1100 rpm. This was used as the highest loading rate in the test, and further loading rates were prepared by dilution. Analytical verification of test concentrations was conducted at 0 and 72 hours, and results are based on nominal concentrations. The test item was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (based on nominal test item concentrations): The EC50-values for inhibition of growth rate and yield were 11.4 mg/L and 7.04 mg/L, respectively. The EC10-values for inhibition of growth rate and yield were 6.21 mg/L and 3.40 mg/L, respectively. The NOEC-values for inhibition of both growth rate and yield were 2.048 mg/L.