Alkenes, C13-14, hydroformylation products, low boiling

Sediment toxicity

Description of key information

The toxicity in sediment organisms of components of Alchisor TAL145 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 (namely, Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), dodecan-1-ol and tetradecan-1-ol).  The only reliable measured data for short-term toxicity to sediment organism for components of TAL 145 was for tetradecan-1-ol.  An assessment factor of 1000 is applicable according to ECHA Chapter R.10 guidance for freshwater sediment which gives a PNEC value of >0.83 mg/kg wwt, (2% organic carbon). However, the guidance also suggests looking at the equilibrium partitioning model to derive the PNEC, which was calculated to be 0.36 mg/kg wwt, and choosing the lower value.  Therefore, the PNEC freshwater-sediment is based on equilibrium partitioning model result of 0.36 mg/kg wwt.  Further assessment is not necessary and the need for further testing for components of Alchisor TAL 145 is waived.

Additional information

Alchisor TAL 145 can be characterised according to three constituents: Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), tetradecan-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 145 and suitable for assessment purposes. The approach taken has been to evaluate together the study data for each constituent, where available. In a protective 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 long-term data were available for Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), tetradecan-1-ol and dodecan-1-ol. Reliable short-term data is available for tetradecan-1-ol only. In accordance with Column 2 of REACH Annex X, the long-term toxicity to sediment organisms does not need to be conducted for Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), tetradecan-1-ol and dodecan-1-ol as discussed below. For completeness, supporting information is provided for PNEC derivation using the equilibrium partitioning method for dodecan-1-ol and tretradecan-1-ol anda reliable short-term test with tetradecan-1-ol. In summary, the requirement for toxicity testing to sediment organisms for Alchisor TAL 145 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, therequirement for terrestrial toxicity testing of C9-C12 aliphatics is waived.

 

Tetradecan-1-ol

No reliable long-term studies for the toxicity of sediment organisms were available for tetradecan-1-ol. One reliable (Klimisch 2) short-term study with sediment organisms was presented by Shell Global Solutions (2004). A 6 day EC50 value of >1000 mg/kg dw soil (1.3% organic carbon) has been determined for the effects of tetradecan-1-ol on population numbers of the ostracod, Heterocypris incongruens. This study is considered key for PNEC calculation.

 

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 waiver for toxicity testing on sediment organisms for dodecan-1-ol.

 

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.

 

In the environment, ready biodegradability means it can be assumed that dodecan-1-ol and tetradecan-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.

 

PNEC derivation

For completeness, PNEC values were calculated by the Long Chain Alcohols Consortium using the equilibrium partitioning method for dodecan-1-ol and tetradecan-1-ol and the assessment factor approach using the short-term data for tetradecan-1-ol:

·        An equilibrium partitioning approach has been used to determine a PNECsediment freshwater for dodecan-1-ol of 1.1 mg/kg wwt;

·        An equilibrium partitioning approach has been used to determine a PNECsediment marine for dodecan-1-ol of 0.11 mg/kg wwt; 

·        An equilibrium partitioning approach has been used to determine a PNECsediment freshwater for tetradecan-1-ol of 0.36 mg/kg wwt;

·        An equilibrium partitioning approach has been used to determine a PNECsediment marine for tetradecan-1-ol of 0.036 mg/kg wwt;

·        An assessment factor approach has been used to determine a PNECsediment freshwater for tetradecan-1-ol of >0.83 mg/kg wwt, (2% organic carbon); and

·        An assessment factor approach has been used to determine a PNECsediment marine for tetradecan-1-ol of >0.083 mg/kg wwt, (2% organic carbon).

 

 

In summary, the toxicity to sediment organisms of components of Alchisor TAL 145 has been documented within this dossier. There was not adequate reliable measured data for the long-term toxicity to sediment organisms to components of Alchisor TAL (namely, Hydrocarbons C11-C14, n-alkanes, isoalkanes, cyclics, aromatics (2-25%), tetradecan-1-ol and dodecan-1-ol). The only reliable measured data for short-term toxicity to sediment organism for components of TAL 145 available was for tetradecan-1-ol. An assessment factor of 1000 is applicable according to ECHA Chapter R.10 guidance for freshwater sediment which gives a PNEC value of >0.83 mg/kg wwt, (2% organic carbon). However, the guidance also suggests looking at the equilibrium partitioning model to derive the PNEC, which was calculated to be 0.36 mg/kg wwt, and choosing the lower value from the two approaches. Therefore, the PNEC freshwater-sediment is based on equilibrium partitioning model result of 0.36 mg/kg wwt. Further assessment is not necessary and the need for further testing for components of Alchisor TAL 145 is waived.