Oct-2-ene

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to microorganisms, other

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 Unknown, guideline study minor restrictions in design and/or reporting but otherwise considered adequate for assessment

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 Alkenes, C6-8-branched, C7-rich (EC 307-298-4 / CAS 97592-99-9) 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 Alkenes, C6-8-branched, C7-rich are mono-constituent and UVCB olefins, respectively. Structurally, the differences between source and target substances include: 1) the length of the carbon chain (uniformly eight for the target substance, but variably six to eight for the source substance); 2) the position of the carbon-carbon double bond (uniformly at the C2 position for the target substance, but variable for the source substance); and 3) the degree of branching (the target substance is a linear, non-branched structure, whereas branching in the source substance is variable).
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 Alkenes, C6-8-branched, C7-rich) 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:

other: OECD 301D

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
not applicable

Analytical monitoring:

no

Details on sampling:

Extent of biodegradation determined by measuring oxygen concentration in the bottles at 5, 15 and 28 days.

Vehicle:

yes

Details on test solutions:

Sodium benzoate used as a biodegradable substance to demonstrate the activity of the microbial inoculum. Controls with no microbial inoculum (control), with medium plus microbial inoculum ony (blank) and with both test and reference substance (toxicity controls) were included. As the test compound was not wholly soluble in water at the concentration used , it was supplied to the degrading organisms as an emulsion in a non-biodegradble detergent, Dobane PT sulphonate. Final test concentration was 2mg/l of test material.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Microorganisms obtained from Sittingbourne Sewage works

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

28 d

Post exposure observation period:

none

Hardness:

data not reported

Test temperature:

21±1°C

pH:

data not reported

Dissolved oxygen:

O2 consumption was the endpoint measured

Salinity:

not applicable

Nominal and measured concentrations:

Test concentration was 2mg/l test material emulsified in Dobane PT sulphonate. Reference substance concentration was 3mg/l.

Details on test conditions:

The bottles were incubated at 21±1°C extent of biodegradation determined by measuring oxygen concentration in the bottles at 5, 15 and 28 days.

Reference substance (positive control):

yes

Remarks:

sodium benzoate

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: inhibition of biodegradation of reference substance

Details on results:

52% ThOD was observed in the toxicity controls after 5 days. The test substance is therefore not inhibitory. The oxygen demand when both the test substance and reference substance were present was not significantly (<20%) lower than the sum of the oxygen demands when these substances were present separately after 28 days.

Results with reference substance (positive control):

not applicable

Reported statistics and error estimates:

data not reported

Validity criteria fulfilled:

yes

Conclusions:

The test substance was not inhibitory to the activated sludge microorganisms at the concentration tested.

Executive summary:

This study was conducted to standard guidelines. The validity criteria of the test guideline were met. The inhibitory effect of olefins C6 -8 was investigated as part of the ready biodegradability screening test, and microbial respiration was not found to be significantly inhibited at the concentration tested.

Reference 2

Endpoint:

toxicity to microorganisms, other

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: Non-GLP, non guideline, published in peer reviewed literature, 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 substances Octene (EC 246-920-8 / CAS 25377-83-7) and Oct-1-ene (EC 203-893-7 / CAS 111-66-0 / alpha-C8) 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.
Octene, Oct-1-ene and Oct-2-ene are linear olefins, each with a carbon chain length of C8. Structurally, the difference between source and target substances is the position of the carbon-carbon double bond. For Oct-1-ene the double bond is at the terminal C1 position (hence, an alpha-olefin), whereas for Oct-2-ene the double bond is at the non-terminal C2 position (hence, an internal olefin). A comparison of the target and source substance properties shows that both substances would be expected to exhibit similar environmental fate, ecotoxicological and mammalian toxicological behaviours. The justification for this read-across from source substances Octene and Oct-1-ene to target substance Oct-2-ene is detailed in section 13 (Document name: “Oct-2-ene Read Across Document HOPA”).
Further, Oct-2-ene and Oct-1-ene both fit within the boundaries of the chemical category of higher olefins. Studies conducted by the HOPA consortium on a large range of higher olefin category members (including Oct-1-ene) demonstrated sufficiently similar physico-chemical, environmental fate and toxicological properties to substantiate the basis for read-across. Therefore Oct-2-ene 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]”).

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

The toxicity of 32 shale oil components to a mixed marine bacterial culture was assessed using an acute static bioassay protocol. The effect of the test substance on culture growth was reported.

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
not applicable

Analytical monitoring:

no

Details on sampling:

data not reported

Vehicle:

yes

Details on test solutions:

test substances were dissolved in Spectrosol grade ethanol

Test organisms (species):

other: mixed marine bacteria

Details on inoculum:

Water samples collected aseptically from Cleveland and Victoria Point, Brisbane, Australia were cultured on marine salts medium solidified with agar. Thirteen different bacterial strains were isolated and transferred to a fresh marine broth, resulting in the removal of all yeasts and fungi. This culture was maintained at 30°C and subcultured weekly.

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

16 h

Post exposure observation period:

none

Hardness:

data not reported

Test temperature:

30°C

pH:

data not reported

Dissolved oxygen:

data not reported

Salinity:

data not reported

Nominal and measured concentrations:

data not reported

Details on test conditions:

The toxicant solutions in ethanol were added to the broth (maximum 0.1ml in 50ml) to yield the required test concentration. This mixture (8ml) was immediately transferred to a sterile Teflon lined , screw capped test tube. A bacterial culture incubated overnight was diluted to a concentration of 8E10 cells/ml and 0.1ml added to the toxicant containing broth. Each experiment was performed in triplicate. Blanks and vehicle blanks were included. All tubes were thoroughly mixed and absorbance at 600nm was measured followed by incubation without shaking at 30°C. After 16 hours the absorbance was remeasured and the differences expressed as a percentage of the difference in the controls.

Reference substance (positive control):

no

Duration:

16 h

Dose descriptor:

EC0

Effect conc.:

other: limit of solubility

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: no effects seen at saturation

Details on results:

EC0 ≥ limit of solubility

Results with reference substance (positive control):

not applicable

Reported statistics and error estimates:

Data were converted to Probit units and a least squares regression used to calculated the EC50 and EC10.

Validity criteria fulfilled:

not applicable

Remarks:

non standard test

Conclusions:

The test substance was not inhibitory to the growth of a mixed marine bacterial culture at levels of 100% saturation.

Executive summary:

This study follows a non standard method and is not conducted to GLP. However, it is well described and demonstrates that the test substance had no inhibitory effect on growth of a mixed marine bacterial culture at concentrations of 100% saturation.

Description of key information

Two key studies were identified. The first key study was a toxicity control conducted on an analogue substance as part of a ready biodegradability test in accordance with OECD Guideline 301D (Miller and Watkins, 1984). The test substance in this study was shown to be non-inhibitory toward the inoculum at a concentration of 2 mg/L. The second key study was a non-guideline study on marine bacteria from the peer-reviewed literature (Warne et al., 1989). The test substance in this study was shown to be non-inhibitory to the growth of a mixed marine bacterial culture at levels of 100% saturation. Therefore, the 16-h EC50 was reported as the limits of test substance solubility.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

2 mg/L