Alcohols, C9-11-branched and linear

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

Data waiving:

other justification

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
In respect of test design and feasibility:
- Standard sediment studies are designed to assess the effects of prolonged exposure to substances which persist in sediments over long time periods. The standard OECD guideline methods for long-term sediment ecotoxicity require spiking of substrate with the test substance initially, with an equilibration phase and in-life exposure phase of several weeks duration, and replenishment during the test is not realistic.
- It is expected that test organism exposure could not be consistently maintained for test substance in a bioavailable form, or primary degradation products, for the duration of a long-term test, due to very rapid biodegradation and mineralisation of bioavailable alcohol in a sediment-water system.
- Considerable technical difficulties would be expected in the conduct of either short or long-term sediment ecotoxicity tests, due to the expected very rapid biotic removal (primary degradation and mineralisation) of bioavailable substance from such a test system.
- Sediment simulation studies (Federle and Itrich, 2010; Itrich, 2010) have demonstrated the very short sediment half-life for the 'readily bioavailable' alcohol 'pool' (see Section 5.2.2); similarly rapid degradation rates are anticipated for other substances in the carbon chain length range C6-24, including this substance.
- for tetradecan-1-ol, in two different natural sediments: half-life 0.04 days and 0.08 days (primary degradation); 0.4 days and 0.15 days (mineralisation)
- for octadecan-1-ol, in two different natural sediments: half-life 1.1 days and 0.04 days (primary degradation); 1.7 days and 0.2 days (mineralisation).
It is considered that this would prevent maintenance of ‘readily bioavailable’ alcohol in pore-water for the duration of a standard long-term test (28 days duration for OECD 225), or even a shorter-term test. (While the sorbed alcohol ‘pool’ has a longer biodegradation half-life (for tetradecan-1-ol, in two different natural sediments: half-life 11.4 days and 11.4 days; for octadecan-1-ol, in two different natural sediments: half-life 17.3 days and 34.7 days (primary degradation)), alcohols are also ‘less bioavailable’ in the sorbed state).
- Please refer to discussion of the long-term aquatic invertebrate and fish studies which were complicated by the rapid degradation in the test system (Section 6.1.2 and 6.1.4).
- Please refer to discussion of the method development for the adsorption/desorption study (decan-1-ol) with natural soils, which was complicated by the rapid removal of test substance in non-sterilised soils (Section 5.4.1 and 5.2.3).

In the context of the chemical safety assessment:
- The substance is readily biodegradable and is very rapidly degradable in all compartments relevant to the environment (please refer to discussion in Section 5.2 of the IUCLID technical dossier for further information).
- In the wider environment, sediment biota are adapted to exposure to fatty alcohols from natural sources (please refer to Section 5.5 of the IUCLID technical dossier for further information).
- The exposure assessment indicates in the course of normal use some releases of alcohols to waste water is possible from both local and wide-dispersive uses. However, investigations have demonstrated that for both freshwater and marine sediments, LCAAs from anthropogenic sources are a minor proportion (1% or less in river environments) of the total present (see Section 5.5 on monitoring data).
- In general it is reasonable to conclude that natural freshwater and marine sediment biota would already be well-adapted to the presence of fatty alcohols from exposure to the many natural sources and the additional exposure to anthropogenic alcohols would not be expected to be a significant concern particularly given that biodegradation would be rapid following release. As such in accordance with column 2 in REACH Annex X, the chemical safety assessment does not indicate a need to investigate further the effects of the substance and/or relevant degradation products on sediment organisms.

Reason / purpose for cross-reference:

data waiving: supporting information

Additional information

In accordance with Section 1.2 of REACH Annex XI (testing does not appear scientifically necessary (based on weight of evidence)), the toxicity to sediment organism study does not need to be conducted based on weight of evidence.

This is based on considerations relating to test design and feasibility and chemical safety assessment context.