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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Endpoint:
biodegradation in water: sediment simulation testing
Data waiving:
study technically not feasible
Justification for data waiving:
the study does not need to be conducted because direct and indirect exposure of sediment is unlikely
Justification for type of information:
The study is not technically feasible as the substance is a complex hydrocarbon UVCB substance. The chemical structure of registered substance, renewable hydrocarbons (gasoline type fraction), is similar to petroleum hydrocarbons. The solubility in water is low though the test may be practically difficult to conduct at concentrations below the water solubility of the substance. A further complication is the volatility of constituent hydrocarbons, which shows a wide variation across the range of carbon numbers and hydrocarbon structures present in the substance. The fate and distribution of the hydrocarbon constituents differ according to their physicochemical properties (water solubility, vapour pressure, log Kow) and the exposure concentrations are dependent on the different degradation rates between constituents and compartments. However, as this substance is fulfilling screening criteria on persistence the additional information is provided by using the PETRORISK model calculation for the Predicted Environmental Concentrations (PECs) of representative hydrocarbons assigned within blocks (defined by analytical data) in various compartments of soil, air, water, waste water treatment plant (WWTP) effluent. In this approach, the individual hydrocarbons with different partitioning and degradation properties were used to simulate the substance fate in the environment. The following hydrocarbon blocks (min-max concentrations in %) were used to assess the environmental risk of this renewable hydrocarbons (naphtha type fraction): -n – paraffins and i-paraffins: 5.3 -6.4 % -normal alkane substituted cyclopentane (n-CC5): 5.2-6.4 % -normal alkane substituted cyclohexane (n-CC6): 4.8-6.0 % -other mono-naphthenics (i-N): 4.8-6.0 % -di-naphthenics (Di-N): 4.4-5.5 % -n-olefins: 5.1 -6.3 % -i-Olefins: 5.0-6.2 % -aliphatic sulphur compounds (Al-S): 3.0-3.9 % -mono-aromatics (Mono-Ar): 3.4-4.7 % -naphthenic mono-aromatics (Nmono-Ar): 2.9-4.0 % -di-aromatics (Di-Ar): 3.3-3.8 % -aromatic sulphur compounds (Ar-S): 3.3-4.1 %

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