4-tert-pentylcyclohexanone

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: read-across from a guideline study

Justification for type of information:

The acute Daphnia toxicity of Orivone is based on read-across from p-tert-butyl-trans-cyclohexanol. The documentation is presented in the Endpoint summary of Aquatic toxicity.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

43.2 mg/L

Basis for effect:

mobility

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 May 2012 to 17 May 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This information is used for read across to Orivone.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

2004

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

2008

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The test item was analytically verified in the fresh media (0 and 24 h) and old media (after 24 h) of all concentration levels and controls. After 48 h, samples of the old media, only of the concentration levels 6.25 and 50 mg/L and the control were analytical verified, because 100% adult mortality was observed at the highest concentration level of 100 mg/L. Sampling from freshly prepared media was carried out immediately after homogenisation. Samples of the old media were taken directly from the vessels.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
The test item was completely melted at temperatures up to 70-90 °C before weighing out. The stock solution (100 mg/L test item was weighed out) was prepared with dilution water one day before star of the exposure phase (0 hours) and water renewal (24 hours). The stock solution was stirred with approcimately 1100 rpm for 24 hours at room temperature. The stock solution was further diluted to obtain the respective test concentrations. A solvent control was prepared from dilution water without test item under the same conditions as the test group.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Strain/clone: STRAUS (clone 5)
- Source: Institut für Wasser-, Boden und Lufthygiene (WaBoLu)
- Breeder: DR.U.Noack-Laboratorien, Käthe-Paulus-Str. 1, 31157 Sarstedt, Germany
- Feeding during test: no

ACCLIMATION
- Acclimation period: at least 2 h in dilution water

STOCK CULTURE MAINTENANCE CONDITIONS
- Culture conditions: in glass vessels (2 - 3 L capacity) with approximately 1.8 L culture medium, at 20 ± 2 °C, in an incubator, 16 h illumination (max 20 µE·m-2·s-1)
- Culture medium: Elendt M4, according to Elendt (1990), modified to a total hardness of 160 to 180 mg CaCO3/L
- Food type: a mix of unicellular green algae, e.g. Pseudokirchneriella subcapitata, Desmodesmus subspicatus and Chlorella vulgaris, with an algal density of >10E+06 cells/mL
- Frequency: at least 5 times per week

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

160 - 180 mg/L (as CaCO3)

Test temperature:

18 - 22 ± 1°C

pH:

7.57 - 8.20

Dissolved oxygen:

8.02 - 8.64 mg/L

Conductivity:

641 µS/cm

Nominal and measured concentrations:

- Nominal concentrations: 0 (control), 6.25, 12.5, 25.0, 50.0 and 100.0 mg/L (based on a range-finding test)
- Measured concentrations (t=0h; new): - Measured concentrations (t=24h; old): - Measured concentrations (t=24h; new): - Measured concentrations (t=48h; old):

Details on test conditions:

TEST SYSTEM
- Age of the daphnids at experimental starting: 2 to 24 h old daphnids were used for the reference test. They were obtained by removing the mother animals twice within 22 h.
- Culture medium: Elendt M4
- Test vessel/volume: With regard to the volatility of the test item sealed glass flasks (4.5 (ID) x 9.5 (H) cm, ca. 130 mL) filled up with the test solution having nearly no headspace to reduce losses of the test item.
- Renewal rate of test solution: Daily. For this purpose, the freshly prepared test solutions were filled into a second set of test vessels and the daphnids were transferred afterwards by a pipette.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Application: The test vessels were filled up with the test solutions. The daphnids were transferred with a small amount of dilution water (start of the exposure) or test solution (water renewal) by a pipette. The test vessels were closed thereafter immediately to reduce losses of the test item.

TEST MEDIUM / WATER PARAMETERS
- Source of dilution water: ISO Test water
- Culture medium different from test medium: no
- Intervals of water quality measurement: 24h

OTHER TEST CONDITIONS
- Photoperiod: 16/8 h light/dark cycle
- Light intensity: diffuse light, light intensity of max. 20 µE·m -² · s -¹

EFFECT PARAMETERS MEASURED
At the beginning of the exposure phase (0 h) and water renewal after 24 hours, the water quality parameters (pH value, dissolved oxygen concentration, temperature, conductivity and total hardness) of the dilution water were measured, respectively. At the beginning of the exposure phase (0 h) and after 24 h, the water quality parameters of the fresh media (pH value, oxygen concentration) were measured in one additional replicate per concentration level and control. After 24 h and 48 h, the water parameters of the old media were measured in all replicates per concentration level and control. The incubator temperature was recorded throughout the test with a hygrothermograph. Immobility was determined in all groups after 24 and 48 h. An animal was considered to be immobile, if it was not able to swim within 15 seconds after gentle agitation of the test vessel.

RANGE-FINDING STUDY: yes
- Test concentrations (nominal): 0 (control), 1.0, 10.0 and 100.0 mg/L
- Results used to determine the conditions for the definitive study: all daphnids were immobile at 100 mg/L; no immobility was observed at the other concentrations

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

43.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% C.L.: 41.3 - 45.1 mg/L

Details on results:

- Mobility: no immobility was observed in the negative control group and up to a concentration of 25.0 mg/L throughout the test. At 50 and 100 mg/L, 90 and 100% daphnia were immobile after 48 h, respectively. See 'Any other information on results incl. tables'. The 48-h NOEC was 25.0 mg/L.
- Mortality of control: no
- Test item solubility: all test item solutions were visually clear throughout exposure

Results with reference substance (positive control):

The 24-h EC50 value of the reference substance was determined to be 1.76 mg/L (Cl 1.50 - 2.01 mg/L) (a reference test is conducted once per month at the test facility).

Reported statistics and error estimates:

EC10 and EC50 values were calculated by sigmoidal dose-response regression. The confidence intervals were calculated from the best-fit values, the standard error and the t-distribution with the software GraphPad prism5. Calculations were using the following software: GraphPad prism5 and Microsoft Excel.

Table: Immobilization Rates after 24 and 48 h of exposure

Nominal Test Item Concentration [mg/L]	Immobilization [%]
	24 h					48 h
	Replicates					Replicates
	1	2	3	4	MV	1	2	3	4	MV
100	100	100	100	100	100	100	100	100	100	100
50	60	60	80	80	70	100	80	100	80	90
25	0	0	0	0	0	0	0	0	0	0
12.5	0	0	0	0	0	0	0	0	0	0
6.25	0	0	0	0	0	0	0	0	0	0
Control	0	0	0	0	0	0	0	0	0	0

MV = Mean value

Validity criteria fulfilled:

yes

Remarks:

see 'Any other information on materials and methods incl tables'.

Conclusions:

The 48-h EC50 is 43.2 mg/L in freshwater invertebrates (D. magna).

Executive summary:

The acute toxicity to aquatic invertebrates was determined in a study according to OECD TG 202 and in compliance with GLP criteria. In this study daphnids (D. magna, 20 per concentration) were exposed to nominal concentrations of 0 (control), 6.25, 12.5, 25.0, 50.0 and 100 mg/L for 48 hours under semi-static conditions. Analytical confirmation of nominal test concentrations showed that all test concentrations remained within ±20% of nominal concentrations throughout the test. Therefore, the effect values are based on nominal concentrations. Immobilization was recorded after 24 and 48 hours exposure. The water quality parameters measured at 24 and 48 h, were determined to be within the acceptable limits. The validity criteria of the test guidelines were fulfilled. After 48 hours, immobility was determined to be 90 and 100% in the two highest test concentrations, whereas at the other (lower) test concentrations no effects were observed. Based on these findings the 48-h EC50 value was estimated to be 43.2 mg/L (95% C.L.: 41.3 - 45.1 mg/L).

Description of key information

No data is available for Orivone. Therefore read-across is performed to the close structural analogue p-tert butyl-trans-cyclohexanol (CAS 98-52-2). Its acute toxicity to aquatic invertebrates was determined in a study according to OECD TG 202 and in compliance with GLP criteria. In this study daphnids (D. magna, 20 per concentration) were exposed to nominal concentrations of 0 (control), 6.25, 12.5, 25.0, 50.0 and 100 mg/L for 48 hours under semi-static conditions. Analytical confirmation of nominal test concentrations showed that all test concentrations remained within ±20% of nominal concentrations throughout the test. Therefore, the effect values are based on nominal concentrations. Immobilization was recorded after 24 and 48 hours exposure. The water quality parameters measured at 24 and 48 h, were determined to be within the acceptable limits. The validity criteria of the test guidelines were fulfilled.After 48 hours, immobility was determined to be 90 and 100% in the two highest test concentrations, whereas at the other (lower) test concentrations no effects were observed.Based on these findings the 48-h EC50 value was estimated to be 43.2 mg/L (95% C.L.: 41.3 - 45.1 mg/L). There is no need to convert the toxicity of the source chemical data towards Orivone, because of the comparable properties of the substances.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

43.2 mg/L