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Ecotoxicological information

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A study is available on the acute ecotoxicity of hydrocarbons, C7-C9, isoalkanes to fish. Data on the acute toxicity to other organisms as well as data on chronic toxicity are read across to both, hydrocarbons, C7-C9, n-alkanes, isoalkanes, cyclics and 2,3,4-trimethylpentane, or estimated using the Petrotox computer model (v. 3.04), which combines a partitioning model used to calculate the aqueous concentration of hydrocarbon components as a function of substance loading with the Target Lipid Model used to calculate acute and chronic toxicity of non-polar narcotic chemicals.

All studies were conducted using Water Accomodated Fractions (WAFs).In this 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).

For acute toxicity to fish a LL50 of 18.4 mg/L was determined. The EL50 value for Daphnia is 2.4 mg/L. Toxicity to algae measured as growth inhibition and biomass ranged from 10-30 mg/L. A study on the chronic toxicity to Daphnia is available. The determination of the long-term toxicity, as measured by survival, sublethal effects, reproduction, and length of first generation adults resulted in a NOELR of 1 mg/L. The chronic aquatic toxicity to fish was estimated as it was done for other organisms. The estimated freshwater fish 28-day NOELR value is 0.778 mg/L based on growth. The estimated EL50 value for the protozoan, Tetrahymena pyriformis, as a representative for microorganisms, is 28.48 mg/L based on growth inhibition.

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