Oct-2-ene

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

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other: Non-GLP, non guideline, available as unpublished report, acceptable with restrictions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-Tetradecene (EC 214-306-9/ CAS 1120-36-1) 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-Tetradecene 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 fourteen 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-Tetradecene) demonstrated sufficiently similar physico-chemical, environmental fate and toxicological properties to substantiate the basis for read-across; although category members of a carbon chain length C10 or greater may exhibit a reduced acute aquatic toxicity attributable to reduced water solubility, the environmental toxicity of all category member is expected to be manifested as non-polar narcosis. In addition, both 1-Tetradecene and Oct-2-ene are expected to exhibit sufficient adsorption to soil and sediment to exhibit similar long-term toxicity; therefore, read-across with respect to sediment and terrestrial toxicity endpoints is appropriate. 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

Principles of method if other than guideline:

The acute and chronic toxicity of the test substance to earthworms was tested in a laboratory bioassay. Natural soil exposed in the field to the test substance was sampled over time. The bulk sample was analysed for physico chemical parameters and the concentration of the test substance. Earthworms were exposed to the soil samples and either their 14 day survival or 70 day effects on growth and reproducion recorded.

GLP compliance:

no

Remarks:

no data reported

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No data reported

Analytical monitoring:

yes

Details on sampling:

A natural silty loam soil was dosed with drill cuttings containing the test substance in September 2001. Soil samples were taken after 2.5, 7, 8 and 10.5 months. 15 soil samples from 0-15cm depth were taken on each occassion, spread evenly across the test and control plots. The samples were bulked and homogenised.

Vehicle:

no

Details on preparation and application of test substrate:

Soil samples collected in the field determined the test concentrations. The bulk soil samples had measured corrected concentrations of 31428, 25195, 8145 and 10026ug/g dry weight over time. Only the concentration of 10026ug/g was tested for chronic effects on earthworms

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

large, healthy, adult worms were used

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

yes

Total exposure duration:

70 d

Post exposure observation period:

none

Test temperature:

22±2°C

pH:

6.5-7.7

Moisture:

remoistened

Details on test conditions:

three replicates of 500cc of remoistened soil were weighed out and placed in 900ml glass jarrs. The earthworms were added to the soil surface and the jars closed with a vented lid. The test was conducted under continual illumination.

Nominal and measured concentrations:

control and 10026ug/g dry weight (measured)

Reference substance (positive control):

no

Key result

Duration:

70 d

Dose descriptor:

NOEC

Effect conc.:

10 026 other: µg/g dry weight

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

70 d

Dose descriptor:

EC100

Effect conc.:

10 026 other: µg/g dry weight

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

70 d

Dose descriptor:

EC50

Effect conc.:

10 026 other: µg/g dry weight

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth

Remarks on result:

other: approximate

Details on results:

No effects on mortality were seen at any test concentration

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Not applicable

Validity criteria fulfilled:

not specified

Remarks:

non standard test

Conclusions:

At the test concentration no effects on mortality were observed but reproduction was completely inhibited.

Executive summary:

At the test concentration no effects on mortality were observed but reproduction was completely inhibited. Although this test does not follow standard guidelines it is well described and includes analytical monitoring of the exposure concentrations. No effects on mortality were observed at the test concentration, however reproduction was completely inhibited. The NOEC reproduction cannot be calculated from this test, and this should be borne in mind whilst deriving the soil PNEC.

Description of key information

The key study was a 70-d toxicity test on the effects of an analog substance on the earthworm Eisenia fetida following a non-guideline test (Visser, 2003).  The study reported values of a 70-d NOEC = 10,026 ug/g d.w. (measured) based on mortality, an EC50 = 10,026 ug/g d.w. (measured) based on growth, and an EC100 = 10,026 ug/g d.w. (measured) based on reproduction. The 70-d NOEC = 10,026 ug/g d.w. (measured) based on mortality was identified as the key value. An additional assessment factor was applied to the 70-d NOEC in the calculation of the candidate PNEC_soil (based on a terrestrial study) to account for the observed effects on growth and reproduction at the lowest test concentration in the study (i.e., the unbounded NOEC for mortality).

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Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil macroorganisms:

10 026 mg/kg soil dw