1-cyclohexylethyl butyrate

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:

experimental study

Adequacy of study:

key study

Study period:

08/02/2002 - 21/03/2002

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)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0.12, 0.26, 0.43, 0.68, 1.1, 2.1, 3.8, 6.6 and 12.4 mg/l (mean measured concentrations)
- Sampling method: Water samples were taken from the control (pooled) and test groups (pooled) at 0 and 48 hours.
- Sample storage conditions before analysis: Samples were frozen at -20ºC until analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: An amount of test material (1100 mg) was dispersed in 11 litres of reconstituted water. This was then stirred at a temperature of 25ºC using a propeller stirrer at approximately 2000 rpm for approximately 48 hours to give an initial test material dispersion of 100 mg/l. After stirring for approximately 48 hours this dispersion was colled to 21ºC and the undisslved test material removed by filtration through a filter (0.2 um) to give a saturated solution of the test material (mean measured concentration of 12.4 mg/l at the end of the test).

Aliquots (20, 36, 64, 112, 202, 357, 636 and 1116 ml) of the saturated solution were each seperately dispersed in reconstituted water and the volume adjusted to 2 litres to provide the remaining measured test concentrations of 0.12, 0.26, 0.43, 0.68, 1.1, 2.1, 3.8 and 6.6 mg/l (mean measured concentrations at the end of the test). Each prepared test concentration was inverted several times to ensure adequate mixng and homogeneity. Due to the suspected volatile nature of the test material, the test vessels were completely filled to minimise headspace and were sealed with ground glass stoppers.
- Controls: Yes

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Source: in-house laboratory culture
- Age at study initiation (mean and range, SD): 1st instar, less than 24 hours old
- Method of breeding: Daphnia were maintained in polypropylene vessels conatining 2 litres of reconstituted water at a temperature of 21ºC. Lighting is 16/8 light/dark cycle with 20 minute dusk/dawn period. Cultures are fed daily with a Chlorella sp. suspension.
- Feeding during test: no

ACCLIMATION
- Acclimation period: none

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg/l CaCO3

Test temperature:

21.0ºC

pH:

7.6 - 7.9

Dissolved oxygen:

8.1 - 8.4 mg/l

Nominal and measured concentrations:

0.12, 0.26, 0.43, 0.68, 1.1, 2.1, 3.8, 6.6 and 12.4 mg/l (mean measured concentrations)

Details on test conditions:

TEST SYSTEM
- Test vessel: flask
- Type: closed
- Material, size, headspace, fill volume: glass, 300ml filled with 300 ml medium
- Aeration: None
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water
- Conductivity: < 5 us/cm
- Culture medium different from test medium: No
- Intervals of water quality measurement: at 0 and 48 hours

OTHER TEST CONDITIONS
- Photoperiod: 16/8 light/dark with 20 minute dusk/dawn transition period

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mobility (daily)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.65 - 2.2
- Range finding study
- Test concentrations: 0.13, 1.3 and 12.9 mg/l
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

4.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95%CL: 4.1-5.3 mg/l

Details on results:

- Mortality/immobilisation of control: 0%

Reported statistics and error estimates:

Data were analysed by trimmed Spearman-Karber method (Hamilton etal, 1977) at 24 hours and the probit method (Finney, 1971) at 48 hours.

Cumulative immobilisation data:

Mean measured test concentration (mg/L)	Cumulative immobilized Daphnia (initial population: 10 per replicate)
	24 hours				48 hours
	R1	R2	Total	%	R1	R2	Total	%
Control	0	0	0	0	0	0	0	0
0.12	0	0	0	0	0	0	0	0
0.26	0	0	0	0	0	0	0	0
0.43	0	0	0	0	0	0	0	0
0.68	0	0	0	0	0	0	0	0
1.1	0	0	0	0	0	0	0	0
2.1	0	0	0	0	0	0	0	0
3.8	0	0	0	0	1	2	3	15
6.6	3	5	8	40	9	10	19	95
12.4	10	10	20	100	10	10	20	100

Concentration-response curves at 24h and 48h are included as illustrations below.

Validity criteria fulfilled:

yes

Remarks:

Mortality in controls <10%, oxygen concentration > 3 mg/l

Conclusions:

The 48h-EC50 of Cyclobutanate towards Daphnia magna is 4.7 mg/l.

Executive summary:

The acute toxicity of Cyclobutanate towards Daphnia magna was investigated according to OECD guideline 202 under GLP. Daphnids were exposed to mean measured concentrations of 0.12, 0.26, 0.43, 0.68, 1.1, 2.1, 3.8, 6.6 and 12.4 mg/l for 48 hours under static conditions. The test material solutions were prepared by stirring an excess (100 mg/1) of test material in reconstituted water and then removing any undissolved test material by filtration. This "saturated" solution was then further diluted, as necessary, to provide the remaining test groups. Chemical analysis of the test solutions throughout the test showed measured test concentrations were between 81% and 123% of the nominal test concentrations at 0 and 48 hours. Although the test material was suspected to be volatile, no significant loss of test material was shown for each of the concentrations over the test period. It was considered that the use of completely sealed vessels with minimal headspace helped to prevent losses of the test material. Therefore it was considered justifiable to calculate the results based on the mean measured test concentrations as opposed to time-weighted mean measured test concentrations. The 48-Hour EC50 for the test material to Daphnia magna based on the mean measured test concentrations was 4.7 mg/l with 95% confidence limits of 4.1- 5.3 mg/l.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

See 'Attached justification'.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

3.58 mg/L

Remarks on result:

other: as determined from read-across to cyclobutanate

Description of key information

The short-term toxicity to aquatic invertebrates is assessed based on read-across from the close structural analogue Cyclobutanate (CAS# 113889-23-9) and the EC50 value determined at 3.58 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

3.58 mg/L

Additional information

The acute toxicity of Cyclobutanate towards Daphnia magna was investigated according to OECD guideline 202 under GLP. Daphnids were exposed to mean measured concentrations of 0.12, 0.26, 0.43, 0.68, 1.1, 2.1, 3.8, 6.6 and 12.4 mg/l for 48 hours under static conditions. The test material solutions were prepared by stirring an excess (100 mg/1) of test material in reconstituted water and then removing any undissolved test material by filtration. This "saturated" solution was then further diluted, as necessary, to provide the remaining test groups. Chemical analysis of the test solutions throughout the test showed measured test concentrations were between 81% and 123% of the nominal test concentrations at 0 and 48 hours. Although the test material was suspected to be volatile, no significant loss of test material was shown for each of the concentrations over the test period. It was considered that the use of completely sealed vessels with minimal headspace helped to prevent losses of the test material. Therefore it was considered justifiable to calculate the results based on the mean measured test concentrations as opposed to time-weighted mean measured test concentrations. The 48-Hour EC50 for the test material to Daphnia magna based on the mean measured test concentrations was 4.7 mg/l with 95% confidence limits of 4.1- 5.3 mg/l.

Aquatic toxicity of Veilex #1 (CAS #63449-88-7) based on read across from Cyclobutanate (CAS #113889-23-9).

Introduction and hypothesis for the analogue approach for Annex VII

Veilex #1 is a butanoic-ester attached to a cyclohexyl-backbone for which no experimental aquatic toxicity data are available. Experimental data of other similar esters are presented for support. In accordance with Article 13 of REACH, lacking information may be generated by other means, i.e. applying alternative methods such as in vitro tests, QSARs, grouping and read-across. For assessing the aquatic toxicity of Veilex#1 the analogue approach is selected because for a closely related analogue, Cyclobutanateaquatic toxicityinformation is available which can be used for read across.Hypothesis: Veilex #1 has similar aquatic toxicity potential as Cyclobutanate asboth substances have cyclic backbones to which a butanoic ester, without any additional reactive functional groups, is attached. Therefore the toxicity is solely based on the difference in log Kow of the substances.

Available information: No aquatic toxicity data are available for the target chemical Veilex #1. For Cyclobutanate experimental data are available.An aquatic algae study was performed according to OECD TG 201. The 72-h ErC50 and NOErC values are 1.95 mg/L and 0.163 mg/L, respectively. The 48-h Daphnia EC50 is 4.7 mg/L (OECD TG 202). The data are reliable without restrictions (Klimisch 1).

Target chemical and source chemical(s)

Chemical structures of the target chemical and the source chemical are shown in the data matrix, including physico-chemical properties and available ecotoxicological information.

Purity / Impurities

Veilex #1 is a mono-constituent with close to 100% purity. It contains no impurities that will affect aquatic toxicity. Cyclobutanate is a mixture of mainly two constituents only differing in the position of the unsaturated double bond being 5yl or 6yl, see Data matrix for the chemical structure. These constituents will not affect the read across.

Analogue approach justification

According to Annex XI 1.5 read across can be used to replace testing when the similarity can be based on a common backbone and a common functional group.

In accordance with ECHA guidance (2015, RAAF) several esters have been looked into and are available for read across, see Table 1. Cyclobutanate is selected based on the butanoic ester attached to a hydrocarbon ring, the similarity in water solubility and calculated log Kow. 

Structural similarities and differences: Veilex #1 and Cyclobutanate are both butanoic esters with acyclic backbone.Veilex#1 has a single ring and an ethyl group between the ring and the ester, while Cyclobutanate has two rings, which results in two-carbons extra for the latter one.

Bioavailability: The bioavailability considering structural features will be similar. The slightly lower molecular weight of Veilex#1 (198, versus 220) and also the slightly higher water solubility of Veilex#1 will not influence the bioavailability of the two substances. The measured log Kow of Veilex#1 is 5.2 and somewhat higher than Cyclobutanate (4.48), while the calculated values KowWin are more alike, 3.55 and 3.8, respectively. Therefore both log Kow values are considered to be in the same range. The log Kow of Cyclobutanate was measured with the shake-flask method, while Veilex#1 is carried out with the HPLC which may explain the measured differences in log Kow. 

Reactivity: Both substances are butanoic esters with non-reactive CH backbones and therefore there will be no difference in reactivity.

Experimental information of similar esters: In table 1 the information of some other cyclic-esters are presented with similar backbones and similar functional groups to further support the read across of these two substances.

Uncertainty of the prediction: There is no remaining uncertainty: the bioavailability and reactivity of both substances are very similar. The measured log Kow of Veilex#1 is somewhat high in relation with the other esters and related to its calculated log Kow value, which cannot be well explained. The high value may be due to experimental variability. For conservative reasons we have used the measured log Kow for conversion from Cyclobutanate (4.48) to Veilex#1).

Data matrix

The relevant information on physico-chemical properties and toxicological characteristics are presented in the Data Matrix, see below.

Table 1 Available esters similar to Veilex#1 from which Cyclobutanate is selected as source chemical

Substance	EC number	CAS no	Log Kow measured	Acute Daphnia measured (mg/L)	Acute Algae measured (mg/L)	EC10/NOEC Alga measured (mg/L)
CP Formate (formic acid)	939-618-9	25225-08-5	3.8	7.7	> 7.1	1.5
Cyclacet (acetic acid)	911-369-0	54830-99-8	3.9	25	25	3.2
Cyclaprop (propionic acid)	272-805-7	68912-13-0	4.4	> 14	2.5	1.95
Cyclobutanate (butanoic acid)	441-420-8	113889-23-9	4.48	4.7	1.95	0.163
Terpinyl acetate (acetic acid)	201-265-7	80-26-2	4.5	10	6.9	0.3
Verdox (acetic acid)	243-718-1	20298-69-5	4.8	17	17	0.3

Conclusions for hazard assessment and environmental classification for an Annex VII

Hazard assessment: For Veilex #1 no experimental aquatic toxicity information is available. The aquatic toxicity values of Cyclobutanate are used for read across to Veilex#1. This results in EC50’s for Daphnia and algae of 3.6 and 1.5 mg/l, respectively and a NOEC for algae of 0.13 mg/l.

Classification and labelling: These hazard values derived for Veilex #1 are in the range of 1-10 mg/L for acute endpoints. The NOEC derived is between 0.1 and 1 mg/l. The substance is rapidly biodegradable but has a measured log Kow of 5.2 (=> 4) and thereforeAquatic Chronic 2 (H411: Toxic to aquatic life with long lasting effects) is assigned.

Data matrix for read across Veilex#1 from Cyclobutanate

Common names	Veilex #1 (CP Butyrate)	Cyclobutanate
	Target	Source
Chemical name	1-cyclohexylethyl butyrate	Butanoic Acid, 3A,4,5,6,7,7A-Hexahydro-4,7-methano-1H-indenyl Ester
Chemical structures	see read across justification document	see read across justification document
CAS no	63449-88-7	113889-23-9 1361017-07-3 (5-yl)
EINECS	264-158-4	639 -061 -9
Empirical formula	C12H22O2	C14H20O2 (generic)
REACH registration	REACH registered (Annex VII, 2018)	REACH registerd (Elincs)
Molecular weight	198	220
Physico-chemical data
Physical state	liquid	liquid
Melting point,^oC	< -20	-20
Boiling point,^oC	246.5	275
Vapour pressure, Pa	6.5	11.2
Water solubility, mg/L	23.8	11.5
Log Kow	5.2 (HPLC)	4.48 (shake flask)
Log Kow (KOWWIN) Log Kow (Sparc)	3.55 4.1	3.8 4.23
Aquatic toxicity data
Aquatic invertebrates EC50 in mg/l	Read across from cyclobutanate: 3.58 (=0.021 mmol/l x 4.48/5.2 (log Kow) x 198 (mw))	Used for read across: 4.7 (0.021 mmol/l x 220 (mw))
Aquatic algae ErC50 in mg/l EC10/NOEC in mg/l	Read across from cyclobutanate: 1.52 (=0.0089 mmol/l x 4.5/5.2 (log Kow) x 198 (mw)) 0.13 (= 0.00074 mmol/l x 4.48/5.2 (log Kow) x 198 (mw))	Used for read across: 1.95 (0.0089 mmol/l x 220 (mw)) 0.163 (0.00074 mmol/l x 220 (mw))