Renewable hydrocarbons (naphtha type fraction)

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil: simulation testing

Data waiving:

study technically not feasible

Justification for data waiving:

the study does not need to be conducted because the substance is readily biodegradable

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 (naphtha type fraction), is similar to petroleum hydrocarbons. 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. 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. In addition, parameters such as aging of the contamination, soil type and characteristics (organic carbon content, electrical conductivity, pH, moisture content) and soil amendments (e.g. inorganic nutrients) will have an influence on biodegradation of hydrocarbons in soil. This makes it difficult to assess biodegradation of these kinds of complex UVCB substances in artificial soils at laboratory scale and measured concentrations from the field studies will no longer directly represent the original composition of the substance. 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 compositional analysis) 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 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 %