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Short-term toxicity to aquatic invertebrates

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The acute toxicity of C9 aromatics hydrocarbons as measured by immobility to the water flea (Daphnia magna) was evaluated in freshwater. Under the conditions of this study C9 aromatics hydrocarbons produced acute toxicity to Daphnia magna at 21.3 mg/L (48-hour EL50), based on nominal loading of the test substance in water, and 6.14 mg/L (48-hour EC50), based on measured concentrations.

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Additional information

The data used to characterize the acute aquatic toxicity of C9 aromatics hydrocarbons are from a short-term toxicity study with Daphnia magna following standard test guidelines. These results indicate that C9 aromatics hydrocarbons causes moderate acute toxicity to freshwater invertebrates at 21.3 mg/L (48-hour EL50), based on nominal loading of the test substance in water, and 6.14 mg/L (48-hour EC50), based on measured concentrations.

In the WAFmethodology, 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).