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Short-term toxicity to fish

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Description of key information

Key value for chemical safety assessment

Additional information

Information on short term toxicity to fish was unavailable for straight run gas oils, however suitable read across information from vacuum gas oils, hydrocracked oils and distillate fuels is available. The 96h LL50 for freshwater fish is 21 mg/L. This data is from Shell report 6304 (1996) and is the most conservative value from the two key studies. This study is considered reliable (2), it is a GLP compliant, near guideline study, with minor restrictions in design and/or reporting but otherwise adequate for assessment.

A wide range of values have been reported for the supporting studies which cannot be compared directly because the studies vary in design, test species and different endpoints have been investigated. Although the Exxon 142958 (1998) study reported a lower LL50, this was not selected as a key study because insufficient data was available to confirm that the test validity criteria were met.

This endpoint has been filled by read-across of measured data from another category. It is supported in a weight of evidence approach by a calculated value using composition information derived from two dimensional gas chromatography in conjunction with the PETROTOX model. The calculated LL50 is 1.3 mg/L.

The aquatic toxicity was estimated using the PETROTOX computer model, 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). PETROTOX computes toxicity based on the summation of the aqueous-phase concentrations of hydrocarbon block(s) that represent a petroleum substance and membrane-water partition coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism. The estimated freshwater fish 96-hr LL50 value is 1.301 mg/L.