Reaction mass of (4Z,8E)-dodeca-4,8,11-trienal and (4E,8Z)-dodeca-4,8,11-trienal

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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 item Dodecatrienal
Batch number V15 Trienal-Dest. F.4-7+V16 Trienal-Dest.F4-8.
Test substance number 18/0072-2
Purity (certified) 91.6 area-% (GC, RTX-1701 capillary)
92.7 area-% (GC, DB-5 MS UI capillary)
Chemical name 4,8,11-Dodecatrienal
Molecular weight 178 g/mol
Appearance Colorless, clear liquid
Expiry date 2020-05-31
Recommended storage Ambient (RT)

Analytical monitoring:

yes

Details on sampling:

All concentration levels and the control and the solvent control were analytically verified via GC-MS at the start (0 hours), after 24h and 48 h and at the end of the exposure (72 hours) with algae.

Vehicle:

yes

Remarks:

DMF (Merck, batch number K50276753823, purity: ≥ 99.8%) was used as a solvent

Details on test solutions:

The test item is a mixture of 3 isomers and has a solubility of 43 mg/L in water. Since the limit of solubility for each isomer may be different, the composition of the test item in solution and the overall solubility may change with the loading of test item/L. Furthermore, the test item is potentially unstable in presence of oxygen. Thus, the test solutions were prepared with defined loadings of the test item. A solvent was used for the preparation of the test concentrations, to keep the stirring period as short as possible to avoid losses of test substance by oxidation and volatility. For the preparation of the test concentrations of the test item Dodecatrienal, appropriate stock solutions were prepared in DMF (solvent). The stock solutions were prepared in measuring flasks (10 mL capacity) by weighing out appropriate amounts of the test item and transferring it into the measuring glass flasks. Thereafter, the flasks were filled up with DMF to 10 mL. The measuring glass flasks containing the stock solutions prepared with DMF were closed and opened only for taking aliquots for preparation of the test concentrations.
The test concentrations were prepared by adding 0.05 mL/L of the appropriate stock solutions to the dilution water under powerful stirring. The dilution water was treated with nitrogen before to reduce the oxygen content, as the test item may be oxidized. Thereafter, the stock solutions were stirred for 1 hour with a magnetic stirrer (room temperature, approx. 1100 rpm). After a separation phase of 1 hour, the test solutions were removed by siphoning (from the approximate bottom of the glass flask) via a glass tube (the glass tube was inserted into the dilution water after stirring and the glass flask was kept covered). The test item solutions were checked visually for undissolved test item (turbidity). No undissolved test item was observed visually

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata HINDÁK CCAP 278/4 (axenic)
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd, Dunstaffnage Marine Laboratory, Dunbeg, OBAN; Argyll PA37 1QA; Scotland, UK

- Age of inoculum (at test initiation): A three days old preculture, prepared in dilution water, was used as inoculum.
- Method of cultivation: Fresh stocks are prepared every month on Z-Agar. Light intensity amounts 2567 – 5130 lux for 24 hours per day.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

0.24 mmol Ca+Mg/L.

Test temperature:

22.8 °C

pH:

7.93 - 8.75

Nominal and measured concentrations:

Nominal: Control, solvent control, 10.0, 3.16, 1.00, 0.316 and 0.100 mg/L
Measured: 7.24, 2.4, 0.784, 0.241 and 0.0728 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Sterile headspace flasks (volume 59 mL) with aluminium tops with PTFE seals
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 59 mL

- Initial cells density: 6442 cells/mL
- Control end cells density: 391695 cells/mL
- Solvent control end cells density: 329495 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control: a additional solvent control with 0.05 mL DMF/L dilution water was prepared and tested under the same conditions as the test group

GROWTH MEDIUM
- Standard medium used: yes

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

OTHER TEST CONDITIONS
- Photoperiod: 24 hours/day light
- Light intensity and quality: Approximately 4440 to 8880 lux,

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The cell density was measured daily via Chlorophyll a-fluorescence, excitation at 436 nm, emission at 685 nm. Dilution water was used as background signal. No self-fluorescence was found in the preliminary range inding test at the saturated solution. Algae cells were evaluated microscopically at the start and the end of the incubation period. The cells were checked for unusual cell shapes, color differences, differences in chloroplast morphology, flocculation, adherence of algae to test containers and agglutination of algae cells.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.08 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.446 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.349 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.847 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The measured concentrations of Dodecatrienal at test start (0 hours) were in the range of 72 to 78% of the nominal values, after 24 hours 57 to 74%, after 48 hours < LOQ to 71% and at test end (72 hours) in the range of a LOQ to 79 % of the nominal values. In this test, oxygen-free test medium was used for the preparation of the test solutions, resulting in stable concentrations of the test item over 72 hours in the two upper test concentrations, demonstrating that losses by volatility during the exposure period under the conditions of this test were negligible. Marked decreases were observed in the concentration range 0.07 – 0.8 mg/L (initial concentration) in replicates with algae, increasing with decreasing concentration.
This can be explained by oxidation by the oxygen produced during algal growth in low concentrations with low or no inhibition of growth. Additionally, biological degradation by the algae might be a factor. Losses of test substance by volatility during preparation of the test solutions could not be ruled out. The measured concentrations of the test item at start of exposure are therefore a conservative estimation of the loading. Effects observed during exposure may be caused by the test item and its degradation products. The results were therefore based on loadings and the measured concentration at start of exposure was considered to be relevant for the evaluation. Thus, all effect values given are based on the nominal and initially measured test item concentrations of Dodecatrienal.

Results with reference substance (positive control):

The toxicity of potassium dichromate (SIGMA-ALDRICH, batch number MKBV0900V, purity 99.0 %, CAS RN 7778-50-9) to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined over a period of 72 hours from 2018-09-25 to 2018-09-28 (with headspace) and 2018-07-10 to 2018-07-13 (without headspace), respectively.
- EC50: with Headspace: 0.799;
- EC50: without Headspace: 0.244

Validity criteria fulfilled:

yes

Conclusions:

In this study, Dodecatrienal was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (based on nominal and analytically verified initially measured test item concentrations): The EC50-values with 95% confidence intervals for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were 1.08 (1.02 – 1.17) mg/L [0.847 (0.797 – 0.922) mg/L] and 0.432 (0.399 – 0.469) mg/L [0.332 (0.306 – 0.361) mg/L], respectively.

Description of key information

Acutely very toxic to aquatic algae

Additional information

In this study according to OCED TG 201, Dodecatrienal was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (based on nominal and analytically verified initially measured test item concentrations): The EC50-values with 95% confidence intervals for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were 1.08 (1.02 – 1.17) mg/L [0.847 (0.797 – 0.922) mg/L] and 0.432 (0.399 – 0.469) mg/L [0.332 (0.306 – 0.361) mg/L], respectively.