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The substance is a complex mixture of hydrocarbon compounds with variable physicochemical and ecotoxicological properties. Application of standard ecotoxicological tests to such UVCB substances includes a number of technical problems such as low water solubility and volatility of the substance. Therefore no tests were conducted and no key information is available. However, information about terrestrial toxicity of fossil fuels to plants and macro-organisms is discussed based on literature. The read-across from fossil fuels is justified based on the similar composition and physicochemical properties compared with the renewable hydrocarbons of wood origin. The read-across justification is presented in annex 1 of the CSR.

In the first supporting study by Molina-Barahona et al. (2005) effectiveness of bioremediation on diesel contaminated soil and the toxicity of the remaining diesel by phyotoxicity test was evaluated. Test was conducted by growing Avena sativa, Triticum aestivum and Carthamus tinctoriu were for 7 days in freshly contaminated and bioremediated soil and their root and stem length, germination rate and biomass weight were measured. In general, diesel had a significant toxic effect on dry weight and also on root and stem elongation of the plant in freshly contaminated soil. This effect was decreased after the bioremediation process. On bioremediated soil, the germination rate decreased on all plants 64 %. Freshly contaminated soil caused greatest reduction in root elongation in safflower (49%) and stem elongation was most affected in wheat (35% reduction compared to control).

Dorn P.B. and Salanitro J.P. (2000) examined the toxicity of soils spiked with crude oil (Light-Gulf of Mexico) before and after of 9 and 11 months of bioremediation in two soil textures, respectively was examined. Norrwood soil was silty loam obtained from cotton field near College Station, Texas, and contained 15 % clay, 60 % silt and 0.3 % organic carbon. The Baccto topsoil was commercially available sandy loam potting soil. Norrwood/Baccto soil mixture consisted 75 % from Norrwood and 25 % from Baccto soil (v/v) and contained 20 % clay, 56 % silt and 4.65 % organic content. Toxicity was examined by conducting 21-days plant growth and germination inhibition tests using corn (Zea mays), wheat (Tritium aestivum) and oat (Avena sativa). Results showed that in untreated soils, the plant seed germination was significantly decreased (50 -100 % inhibition) in all plants, but in bioremediated soils, seed germination was not significantly lower than in control soils. Plant growth was similarly reduced significantly in untreated soil, but although growth was enhanced in bioremediated soils, it was still 0-40 % lower compared to control soil.

Same authors (Dorn P.B. and Salanitro J.P. 2000) also examined toxicity of by conducting 14-days LC50 tests using earthworms (Eisenia fetida). Results from the earthworm tests showed, that all contaminated soils were acutely toxic to Eisenia in the first 2-4 weeks of bioremediation. Norrwood soil spiked with light crude oil remained toxic for 12 months, whereas in Norrwood/Baccto soil spiked with light crude oil all animals survived after 3 months of treatment. Results showed that contamination decreased during the bioremediation and the loss of toxicity correlated with optimum degradation in soils with exception of low organic Norrwood soil.

In conclusion, diesel showed toxic effects on plants with concentrations of 45 g/kg in untreated soil that had total organic matter of 6.5 %, when oat, wheat and safflower growth decreased 20, 30 and 35 % respectively compared to control (Molina-Barahona et al. 2005). Plant growth was still affected with diesel concentration of 1 mg/kg in bioremediated soil with organic content 0.3 %, when corn, wheat and oat weight decreased 16, 32 and 50 % respectively compared to control (Salanitro J.P & Dorn P.B. 2000). Diesel was also toxic to earthworms in concentration 4.2 g/kg (LC50 as soil % was 22 %) in soil with 6.5 % organic content and 9.2 g/kg (LC50 as soil % was 34 %) in soil with 0.3 % (Salanitro J.P & Dorn P.B. 2000). In general, higher amount of organic matter in soil seemed to decrease the toxic effect.

Soil toxicity tests for hydrocarbon substances have number of technical problems, such as water solubility and volatility. The fate and toxicity of these substances are also affected by weathering and aging of the fuel. Terrestrial toxicity also depends on soil characteristics such as particles size, carbon content and soil texture. Because of these problems, ecotoxicity tests for hydrocarbon contaminated soils don't always give direct correlation between concentrations and toxicity.