Cyclohexadecen-1-one

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

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 202 (Daphnia sp. Acute Immobilisation Test)

Qualifier:

according to guideline

Guideline:

other: OECD series on testing and assessment no. 23 (second edition)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Sampling method: All concentration levels and the control were analytically verified via GC-MS in the fresh media at the start of exposure and at the renewal of the test solutions (0 and 24 hours) as well as in the 24-hours old media at the renewal and at the end of the exposure (24 and 48 hours).

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: In a glass column an appropriate amount of sea sand (washed twice with acetone) was spiked with an appropriate amount of the test item as follows. An appropriate amount of the test item was dissolved in an apropiate amount of acetone. An appropriate amount of this stock solution were mixed thoroughly with 23.4 g of the sea sand in a glass petri dish. After complete evaporation of the solvent, the dry sea sand was filled into the column. The column was connected with a tubing pump. For preparation of the saturated solution, the generator column was rinsed with demineralized water in a circuit within 95 hours by a tubing pump. After 4 days, an aliquot of 1000 mL of the saturated solution was taken from the center of the water body and was checked for undissolved test item (formation of an emulsion). The Tyndall effect was negative and, thus, undissolved test item was not present. Thereafter, the mineral components of the dilution water were added.
- Preparation test concentrations: The saturated solution containing the mineral components was used as the highest concentration level and as a stock solution for the preparation of further concentration levels by dilution with dilution water.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Age at study initiation: Less than 24 hours
- Source: Institut für Wasser-, Boden- und Lufthygiene (WaBoLu), Germany
- Feeding during test : non

CULTURE
- Medium: Elendt M4, according to OECD 202, Annex 3 (2004)
- Feeding: at least 5 times per week ad libitum with a mix of unicellular green algae, e.g. Pseudokirchneriella subcapitata and Desmodesmus subspicatus

ACCLIMATION
- Acclimation period: Acclimatization was not necessary, composition of the dilution water was equivalent to the culture medium.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

269 - 278 mg CaCO3/L

Test temperature:

20.8 - 21.3 °C

pH:

0 h: 7.6 - 8.4
24 h (old): 7.6 - 8.2
24 h (new): 7.3 - 8.2
48 h: 7.3 - 7.8

Dissolved oxygen:

0 h: 8.19 - 8.74 mg/L
24 h (old): 8.06 - 8.69 mg/L
24 h (new): 7.65 - 8.15 mg/L
48 h: 7.00 - 8.10 mg/L

Conductivity:

589 - 592 µS/cm

Nominal and measured concentrations:

Nominal dilution levels: control, 6.25 - 12.5 - 25.0 - 50.0 - 100% of the saturated solution
Geometric mean measured concentrations: control, 51.4 – 101 – 192 – 366 – 834 µg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Sealed glass flasks with screw caps
- Type: closed
- Headspace, fill volume: no headspace, 130 ml fill volume
- Volume of solution: 130 ml
- Aeration:none
- Renewal rate of test solution: every 24 hours
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: no
- Intervals of water quality measurement:
- Temperature was recorded throughout the period of the test.
- Dilution water: pH value, dissolved oxygen concentration, temperature, conductivity and total hardness prior to the start of the exposure (0 hours) and the renewal of the test solutions (24 hours)
Test solution: At 0 and 24 hours (new medium), pH value, dissolved oxygen concentration) were measured in one additional replicate per concentration level and control. At 24 and 48 hours (old medium) in one appropriate replicate (containing daphnids) per concentration level and control. The replicate with the highest immobilization rate per concentration level and control was measured


OTHER TEST CONDITIONS
- Photoperiod: 16/8 hours light/dark cycle
- Light intensity: Diffuse light, light intensity of max. 1500 lx

EFFECT PARAMETERS MEASURED: Immobilization after 24 and 48 hours and any adverse, sub-lethal effects (e.g. discoloration, abnormal behavior etc.)

RANGE-FINDING STUDY
- Test concentrations: control, 1, 10, 100% of saturated solution
- Results used to determine the conditions for the definitive study: 100% immobilization in 100% of the saturated solution

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

265 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% confidence limits: 241 – 292 µg/L

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

192 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

834 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: none
- Other biological observations: none
- Mortality of control: none
- Other adverse effects control: none
- Immobilisation of control: none
- Abnormal responses: none

Results with reference substance (positive control):

EC50 (24 h) = 2.17 mg/L

Measured Concentrations of the Test Item during the Definitive Test

Sampling	Fresh media, 0 hours	Old media, 24 hours		Fresh media, 24 hours	Old media, 48 hours
Dilution level of the saturated solution [%]	test item
	Meas. conc. [µg/L]	Meas. conc. [µg/L]	%	Meas. conc. [µg/L]	Meas. conc. [µg/L]	%	Geometric mean Measured concentration [µg/L]
100	1060	624	59	1193	613	51	834
50.0	444	297	67	458	298	65	366
25.0	242	154	64	230	159	69	192
12.5	113	73.9	66	147	86.2	59	101
6.25	57.0	40.3	71	73.1	41.6	57	51.4
Control	< LOQ	< LOQ		< LOQ	< LOQ		< LOQ

Meas. conc. = measured concentration of the test item

% = percentage of the initially measured concentration of the test item

LOQ = limit of quantification (4 µg test item/L)

Immobilization Rates after 24 and 48 hours of Exposure in the Definitive Test

Geometric mean measured test item concentration [µg/L]	IMMOBILIZATION [%]
	24 hours					48 hours
	Replicates					Replicates
	1	2	3	4	MV	1	2	3	4	MV
834	100	80	100	100	95	100	100	100	100	100
366	60	60	80	60	65	80	80	100	100	90
192	0	0	0	0	0	0	0	20	20	10
101	0	0	0	0	0	0	0	0	0	0
51.4	0	0	0	0	0	0	0	0	0	0
Control	0	0	0	0	0	0	0	0	0	0

Validity criteria fulfilled:

yes

Conclusions:

Based on the geometric mean measured concentrations of the test item the 48 hours-EC50 for Daphnia magna was 265 µg/L (95% confidence limits: 241 – 292 µg/L).

Description of key information

The 48-hour EC50 for Daphnia magna = 265 µg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

265 µg/L

Additional information

One acute invertebrates toxicity study is available. The short-term toxicity to Daphnia magna was determined in a 48 hour test according to OECD guideline 202 and conducted in compliance with GLP (2019). Organisms were exposed to measured concentrations (geometric mean) of 51.4, 101, 192, 366 and 834 µg/L in a closed system under semi-static conditions. The EC10, EC50 and EC100 based on mobility were determined to be 192, 265 and 834 µg/L, respectively. This study is considered reliable and relevant (Klimisch 1) and is suitable for use as a key study.