Cyclohexadecen-1-one

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 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

GLP compliance:

yes

Details on sampling:

- Concentrations: control, saturated solution
- Sampling method: Samples were taken at the start and the end of exposure

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:Following the recommendations of OECD guidance document no. 23 (2000)6, a column elution system as generator system was applied. Once for the test a HPLC column (length 25 cm x i.d. 4.6 mm = volume 4.2 cm3 ) was prepared prior to test start. For the preparation of the column 7.8 g (5 cm3) of quartz sand (washed twice with aceton) were spiked with 15 mg of the test item. The optimal ratio of the test item stock solution to quartz sand is 0.24 mL / 1 g. The test item (401 mg were weighed out) was dissolved in 50 mL acetone and mixed thoroughly with the quartz sand in a glass petri dish. After complete evaporation of the solvent, the dry quartz sand was filled in the HPLC column. Lower homologues and impurities were purged by rinsing the column with 200 mL of dilution water. For preparation of the saturated solution the generator column was rinsed with approx. 3 L of dilution water in a circuit within 96 hours by a HPLC-pump with a flow rate of 1.2 mL/min.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Green alga
- Strain: SAG 86.81
- Source: Sammlung von Algenkulturen (SAG), Pflanzenphysiologisches Institut der Universität Göttingen, Göttingen, Germany
- Age of inoculum (at test initiation): four days
- Method of cultivation: Fresh stocks were prepared every month an Z-Agar. Light intensity amounted 35-70 µE*m^-2* s^-1 for 24 h per day.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

21-22 °C

pH:

7.9 - 9.7

Nominal and measured concentrations:

nominal: 100% saturated solution
initial measured concentrations: 912 µg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: sterile headspace flasks with aluminium tops with PTFE seals
- Type: closed
- Headspace, fill volume: no headspace, 119 mL
- Aeration: no
- Initial cells density: 5601 cells/mL
- Control end cells density: 361131 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: According to the guideline
- Intervals of water quality measurement: The pH-value at the beginning of the test was measured out of one additional replicate of the limit concentration and control. At the end it was measured from one pool per concentration of all replicates.

OTHER TEST CONDITIONS
- Light measurememts: Light intensity was measured prior to test start.
- Photoperiod: 24 h/d light
- Light intensity and quality: 76 - 87 µE • m-2 • s-1

EFFECT PARAMETERS MEASURED:
- Microscopic evaluation of the cells at the start and at the end of the incubation was determined. Cells were checked for any unusual cell shapes, colour differences, chloroplast morphology, flocculation, adherence of algae to test containers or aggregation of alga cells
- Chlorophyll measurement: Cell density was measured via Chlorophyll-a-fluorescence, excitation at 435 nm after 0, 24, 48, 72, 96 h


TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: saturated solution, 1:10
- Results used to determine the conditions for the definitive study: no toxic effects were found in the saturated solution

Reference substance (positive control):

yes

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.912 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 0.912 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.912 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 0.912 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): none

Results with reference substance (positive control):

- Determined over a period of 72 h from September 10 to 13, 2007
- ErC50 = 1.01 mg/L
- EyC50 = 0.42 mg/L

Table 1: Test item concentrations

Sampling date	2008-01-22 Test start	2008-01-25 Test end
Start of analysis	2008-01-22	2008-01-25
Saturated solution	Test item
	Meas. Conc. [mg/L]	Meas. Conc. [mg/L]	RR [%]
1:1 without algae	0.912	0.890	98
1:1 with algae	Not measured	0.423	46
Control	< LOQ	< LOQ	—

Meas. conc. = Measured concentration, dilution factor taken in account, mean value of 2 injections

RR          = Recovery rate related to the initially measured concentration

LOQ       = Limit of quantification

Validity criteria fulfilled:

yes

Conclusions:

In this study the test item did not cause inhibitory effects on growth rate of algae after 72 h up to the solubility limit (saturation solution level under test conditions: 912 µg/L as inital mean measured concentration)

Description of key information

The 72 -hour ErC50 and ErC10 for Pseudokirchneriella subcapitata > 912 µg/L (solubility limit).

Additional information

One experimental algae study according to OECD 201 and GLP is available. This limit test was conducted under static conditions in a closed system with no headspace. Pseudokirchneriella subcapitata cells were exposed to saturated solution of the test item and the control. In this study the test item did not cause inhibitory effects on growth rate of algae after 72 h up to the solubility limit (saturation solution level under test conditions: 912 µg/L as inital mean measured concentration).