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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

The acute toxicity of hydrocarbons, C9 aromatics as measured by mortality to rainbow trout (Oncorhynchus mykiss) was evaluated in freshwater. Under the conditions of this study, C9 aromatics hydrocarbons produce acute lethal toxicity to Oncorhynchus mykiss at 9.2 mg/L, based on nominal loading of the test substance in water.

Key value for chemical safety assessment

Additional information

Water accommodated fractions of hydrocarbons, C9, aromatics, produced a 96-hour LL50 value of 9.2 mg/L with rainbow trout, Oncorhynchus mykiss.

Substance is a hydrocarbon UVCB that posesan acuteaquatic hazard. The hydrocarbon block method is used for environmental risk assessment (see REACH guidance, R7, app.13-1). Aquatic PNECs for hydrocarbon blocks have been derived using the HC5 statistical extrapolation method and the target lipid model using representative structures. See Product Library tab in PETRORISK spreadsheet attached to Section 13. Given the large database of freshwater organisms included in the target lipid model, an assessment factor of one has been applied to the HC5.

In the WAF methodology, different loadings of the substance are added to the test medium and equilibrium between the water and the hydrocarbons is achieved according to their specific water solubility. The hydrocarbon concentrations at equilibrium will be characteristic of the loading of the substance, and therefore toxicity values from WAF studies are expressed as effect loadings or lethal loadings (EL or LL), not as concentrations. These effect loadings are used to determine environmental classifications. The WAF methodology is widely accepted for the testing of complex hydrocarbon substances and other UVCBs, and it has been incorporated in different guidance documents, including the REACH guidance (see draft decision response letter in Section 13).