Registration Dossier

Administrative data

Hazard for aquatic organisms

Hazard for air

Hazard for terrestrial organisms

Hazard for predators

Additional information

Aquatic PNECs were derived using the PETROTOX model. As the aquatic PNEC are greater than the water solubility of the test substance toxicity is not expected and so soil and sediment PNECs are not calculated.

Conclusion on classification

All the acute ecotoxicity data for Alkenes C24 - 28 are read across from other category members and are expressed in terms of loading rate rather than exposure concentrations. These data are not suitable for comparison with the classification criteria. Poorly water soluble substances may require a precautionary classification of R53 "May cause long term adverse effects in the aquatic environment" under the DSD and Chronic Category 4 under the CLP Regulations.


This precautionary classification is not triggered if the substance is readily biodegradable or has a log Kow <3 (DSD) or <4 (CLP Regulations). Alkenes C24 - 28 is not considered readily biodegradable and has a calculated log Kow >10. Therefore, the precautionary classification applies. The clause to remove the precautionary classification is based on demonstrating that the substance shows no chronic toxicity at the limit of solubility. Experimental chronic toxicity is not available at this carbon number range. However, the following justification is submitted in support of the removal of R53, Chronic Cat 4 for the C24 and higher olefins.


1. All the acute ecotoxicity data for category members demonstrates that there is an acute toxicity cut-off at approximately C12 – C14. Based on an acute to chronic ratio of <10 for non-polar narcotics, and acute/chronic toxicity QSARs, the change in carbon length at which chronic toxicity would also not be exhibited would be at least 2 carbon units higher (equivalent to a log Kow change of approx 1). Suggesting C16 as the lower limit at which chronic toxicity would be observed. This observation is also supported by the following two QSAR predictions;


2. In running PETROTOX/HC5 (Redman et al., 2010) – a prediction of no acute or chronic toxicity at the limit of solubility for these carbon chain-lengths, >C24 is obtained.


3. ECOSAR (Nabholz and Mayo-Bean, 1998) predictions indicate that no acute of chronic toxicity is expected at the limit of solubility for alkenes of C24 and above.


4. Historically CONCAWE (CONCAWE, 2001) in assessing Waxes (C20 – C50 (iso)alkanes and cyclic alkanes), Foots Oil (C20 – C50 isoalkanes), Slack Waxes ( C12 – C50, (iso)alkanes) and Petrolatums (C20 – 85 (iso)alkanes and cyclic alkanes) have used the same read-across argument :


QSAR assessment of the toxicity of the substances in this group, based on their hydrocarbon composition, indicates that they would not be expected to cause acute toxicity to aquatic organisms. Substances in this group do not meet the criteria for ready degradability. However, based on read across of chronic toxicity results from related high molecular weight hydrocarbons (i.e., lubricants and hydrocarbon solvents), the substances in this group would not be expected to pose a long-term hazard to the environment.


5. Finally – the most recent data available from the CONCAWE assessment of petroleum hydrocarbons (CONCAWE, 2010) reviews the chronic ecotoxicity of the lower carbon chain lengths (<C20). A solubility cut-off of 1 – 10 µg/l is discussed as the limit of chronic aquatic toxicity. This clearly demonstrates that the C24 and above olefins with calculated solubilities of <1 ng/L would be extremely unlikely to be able to exert toxicity in the aquatic environment.  


Based on this justification, Alkenes C24 - 28 is not given the precautionary classification of R53, Chronic Cat 4.