Oct-2-ene

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

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other: GLP compliant, guideline study, available as unpublished report, acceptable with restrictions

Justification for type of information:

Read-across between the target substance Oct-2-ene (EC 203-894-2 / CAS 111-67-1) and source substance 1-Decene (EC 212-819-2/ CAS 872-05-9) is based upon the similarity of the chemical structures and their respective physico-chemical properties. The ECHA Read-Across Assessment Framework (RAAF) states that substances with qualitatively similar properties can form the basis of read-across in circumstances where the source and target substances share such similar characteristics.
Target substance Oct-2-ene and source substance 1-Decene are each mono-constituent linear olefins. Structurally, the differences between source and target substances include: 1) the length of the carbon chain (eight for the target substance, and ten for the source substance); and 2) the location of the carbon-carbon double bond (uniformly at the C2 position for the target substance, but uniformly at the C1 terminal position for the source substance).
The target and source substances both fit within the boundaries of chemical category of higher olefins. Studies conducted by the HOPA consortium on a large range of higher olefin category members (including 1-Decene) demonstrated sufficiently similar physico-chemical, environmental fate and toxicological properties to substantiate the basis for read-across; category members in the C6-C10 range may be moderately toxic to highly toxic to aquatic organisms and environmental toxicity is expected to be manifested as non-polar narcosis. Therefore Oct-2-ene (which falls within the C6-C10 range) is expected to behave similarly. Justification for inclusion of Oct-2-ene within the boundaries of the higher olefins category, and the relevance of each category member as an analogue substance to Oct-2-ene, is provided in Section 13 (Document name: “HOPA Higher Olefins CJD with Category Matrix Report [rev 1 Sept 2016]”; Document name: "ACC Product Stewardship Summary for Higher Olefins Category (2008-12-03)”).

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Daily renewal of test media with on off analysis

Vehicle:

yes

Details on test solutions:

A concentrated 10 mg/ml stock solution of dec-1-ene was made by adding 100mg in 10 ml DMF.

The required amount of the stock solution was then added to dechlorinated water and stirred for 48 hours in airtight sealed vessels with the minimum headspace to give the required exposure concentrations. DWC and solvent control test solutions were also be stirred for 48 hours.

Test organisms (species):

Daphnia magna

Details on test organisms:

<24 hours old at the start of the test, and not first brood progeny, derived from continuous laboratory cultures. The temperature and dilution water used for culturing the D. magna will be the same as used for the test.

Test type:

other: daily renewal

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Salinity:

not applicable

Nominal and measured concentrations:

Nominal concentrations of 0.056, 0.10, 0.18, 0.32, 0.56, 1 and 1.8 mg/l.
Mean measured concentrations of

Details on test conditions:

Test vessels were glass bottles of 50 ml nominal capacity, filled completely (approximately 60 ml of test solution), with airtight, Teflon faced disc/crimp closures. Elendt M4 test media used. Photoperiod will be controlled to provide 16 hours light: 8 hours dark, with a 20 minute dawn:dusk transition period.Twenty (4 replicates of 5) organisms will be tested for each test concentration.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.56 - 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.56 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

No mortality in dilution water control or solvent control

Validity criteria fulfilled:

yes

Conclusions:

The 48 hour EC50 for Daphnia magna lies between 0.56-1.0 mg/l.

Executive summary:

The toxicity of dec-1 -ene to Daphnia magna was investigated in an OECD 202 test (Brixham Environmental Laboratories, 2010). Due to the low solubility of the test substance the study used a solvent carrier. The test substance was mixed with the solvent before being added to the dilution water. It was then stirred for 48 hours under sealed conditions to maximise the exposure concentrations. The test was carried out with sealed test vessels and the solutions were renewed daily to minimise the loss of the test substance.

At the lower loading rates (0.056 -0.1mg/l) the measured concentrations were below the limit of detection throughout the test. Only the highest exposure concentration had detectable levels of dec-1 -ene after each 24 hour renewal period. Due to the loss of test compound over time the results are reported based on nominal loading rates. The 48 hour EC50 lies between 0.56 and 1 mg/l and the analytical monitoring indicates that the mean exposure concentration at 1mg/l was below the limit of solubility of dec-1 -ene.

Description of key information

The key study was a semi-static acute invertebrate toxicity test on the effects of an analog substance on the freshwater invertebrate Daphnia magna following OECD Guideline 202 (Brixham Environmental Laboratories, 2010). The 48-h NOEC was reported as 0.56 mg/L and the 48-h LC50 was reported as > 0.56 mg/L and < 1 mg/L based on nominal concentrations.  The key value was represented by the minimum value from the reported range of EC50 values in the key study.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.56 mg/L