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Sediment toxicity

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Description of key information

The toxicity in sediment organisms of components of Alchisor TAL 123 has been considered within this dossier. However, there was not adequate reliable measured data for the long-term toxicity to sediment organisms to components of Alchisor TAL 123 (namely, Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), undecan-1-ol and dodecan-1-ol).  Testing with Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), undecan-1-ol or dodecan-1-ol was deemed not necessary and is waived.  The waiver is applied for this endpoint as the substance is readily biodegradable in the environment.
For completeness, PNECsediment freshwater values were provided by the Long Chain Alcohols Consortium using the equilibrium partitioning method for undecan-1-ol (1.612 mg/kg; wet weight) and dodecan-1-ol (1.1 mg/kg; wet weight) for freshwater. PNECsediment marine values using the equilibrium partitioning method for undecan-1-ol (0.1612 mg/kg; wet weight) and dodecan-1-ol (0.11 mg/kg; wet weight).

Key value for chemical safety assessment

Additional information

Alchisor TAL 123 can be characterised according to three constituents: Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), undecan-1-ol and dodecan-1-ol. As defined in the Read-Across Justification Document in section 13, data provided for these constituents when considered together is representative of Alchisor TAL 123 and suitable for assessment purposes. The approach taken has been to evaluate together the study data for each constituent, where available. In a conservative approach the most sensitive study result from across the three constituents would be identified and used to address the endpoint in question. However, no reliable measured data were available for Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), undecan-1-ol and dodecan-1-ol. In accordance with Column 2 of REACH Annex X, the toxicity to sediment organisms does not need to be conducted for Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), undecan-1-ol and dodecan-1-ol. In addition, arguments exist to support evidence for waiving data requirements for this endpoint for these constituents as discussed below. For completeness, supporting information is provided for undecan-1-ol and dedecan-1-ol where PNECs were calculated using the equilibrium partitioning method. In summary, the requirement for toxicity testing to sediment organisms for Alchisor TAL 123 is waived.

Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%)

Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%) is a hydrocarbon UVCB. Standard tests for this endpoint are intended for single substances and are not appropriate for this complex substance due to the substances complex nature and solubility. In addition, the substance is readily biodegradable (the test substance was 74.7% degraded by day 28 and met the 10-day window requirement) and the direct or indirect exposure of the soil compartment is unlikely. Therefore, the requirement for terrestrial toxicity testing of C9-C12 aliphatics is waived.

Undecan-1-ol and Dodecan-1-ol

In accordance with Column 2 of REACH Annex X, the long-term toxicity effects studies to sediment dwelling organisms (required in Section 9.5.1) is waived as the study is technically not possible. This is due to the very short sediment half-life once desorbed (see CSR for further details), which do not allow for the studies to be conducted. Adequate evidence of low solubility and high degradation, as described below, supports the application of a wavier for toxicity testing on sediment organisms for undecan-1-ol and dodecan-1-ol. By way of completeness, freshwater and marine PNECsediment values were calculated using the equilibrium partitioning method.

Biodegradation

According to the SIDS SIAR for Long Chain Alcohols (2006) reliable measured data (e.g. for hexanol, octanol, decanol, dodecanol, tetradecanol, hexadecanol and octadecanol) show that alcohols with chain lengths up to C18 are readily biodegradable. At carbon chain lengths up to C16, most tests showed that pass levels for ready biodegradation were reached within the 10-day window, with removal levels up to 100% over the timescale of the test. In additional studies conducted at environmentally realistic concentrations with radio-labeled substances (C12-16), very high rates of degradation have been measured (very rapid rate constants, with ca. 75-85% removed as CO2 and metabolites). These rates accord with field data for measured concentrations in waste-water treatment plant influent and effluent showing greater than 99% removal for carbon numbers 12 to 18. This summary of degradation is applicable to both linear and branched components of substances in the category. Therefore, the whole category is considered to show very high levels of biodegradability. Rapid degradation is also indicated by the removal rates in the chronic aquatic toxicity tests for the lower solubility substances (C10 to C15), where rapid removal of the substance from the test medium was observed, most likely due to biodegradation by micro-organisms.

A weight of evidence approach was taken to determining the ready biodegradability of the C11 alcohol, undecan-1-ol by using data for both C10 and C12 alcohols. In a study by Richterich (2002), 88% degradation within 30 days of lorol 1-decanol (C10) was reported. A variety of different studies have been conducted with the C12 alcohol, dodecan-1-ol, where reliable data confirming ready biodegradability ranged from 79% to 100% within 28 days (Werner, 1993). Other studies by the Vista Chemical Company (1994), Morris (1991), Henkel (1992) and P&G (2009) using all reported dodecan-1-ol was "inherently biodegradable" or "readily biodegradable". The weight of evidence presented here indicates that dodecan-1-ol can be regarded as readily biodegradable.

Reliable studies indicate that both linear and branched alcohols with a chain length below C18 are readily biodegradable. In the environment, ready biodegradability means it can be assumed that undecan-1-ol and dodecan-1-ol will be biodegraded within the STP process and as a consequence a transfer to the sediment compartment via STP effluent is not expected. Furthermore, for substances not passing the STP-process but being readily biodegradable, it can be assumed that they will be also biological degraded in the surface water within a short time.

Equilibrium Partitioning

PNEC values were calculated for undecan-1-ol and dodecan-1-ol, by the Long Chain Alcohols Consortium, using the equilibrium partitioning method:

• Equilibrium partitioning has been used to determine a PNECsediment freshwater for undecan-1-ol of 1.612 mg/kg wwt;

• Equilibrium partitioning has been used to determine a PNECsediment marine for undecan-1-ol of 0.1612 mg/kg wwt;

• Equilibrium partitioning has been used to determine a PNECsediment freshwater for dodecan-1-ol of 1.1 mg/kg wwt; and

• Equilibrium partitioning has been used to determine a PNECsediment marine for dodecan-1-ol of 0.11 mg/kg wwt.

The toxicity in sediment organisms of components of Alchisor TAL123 has been considered within this dossier. However, there was not adequate reliable measured data for the toxicity to sediment organisms to components of Alchisor TAL 123 (namely, Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), undecan-1-ol and dodecan-1-ol). Testing with Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), undecan-1-ol or dodecan-1-ol was deemed not necessary and is waived. The waiver is applied for this endpoint as the substance is readily biodegradable in the environment.

For completeness, PNECsediment freshwater values were provided by the Long Chain Alcohols Consortium using the equilibrium partitioning method for undecan-1-ol (1.612 mg/kg; wet weight) and dodecan-1-ol (1.1 mg/kg; wet weight) for freshwater. PNECsediment marine values using the equilibrium partitioning method for undecan-1-ol (0.1612 mg/kg; wet weight) and dodecan-1-ol (0.11 mg/kg; wet weight). These values are provided for information and for consistency with the individual corresponding dossiers. However, PNECsediments were derived for Alchisor TAL 123 using EUSES for the purposes of the CSA.