Vegetable oils and their derivatives, like biodiesel, are used extensively throughout the world, thus posing an environmental risk when disposed. Toxicity testing using test organisms shows how these residues affect ecosystems. Toxicity tests using earthworms (Eisenia foetida) are widespread because they are a practical resource for analyzing terrestrial organisms. For phytotoxicological analysis, we used seeds of arugula zero days, 60 days, 120 days and 180 days. The studied contaminants were soybean oil (new and used) and biodiesel (B100). An evaluation of the germination of both seeds showed an increased toxicity for all contaminants as the biodegradation occurred, biodiesel being the most toxic among the contaminants. On the other hand, for the tests using earthworms, the biodiesel was the only contaminant that proved to be toxic. Therefore, the higher toxicity of the sample containing these hydrocarbons over time can be attributed to the secondary compounds formed by microbial action. Thus, we conclude that the biodegradation in soil of the studied compounds requires longer periods for the sample toxicity to be decreased with the action of microorganisms.

The aim of this work was to compare different toxicity levels of lubricant oils. The tests were performed using the earthworm (Eisenia andrei), arugula seeds (Eruca sativa) and lettuce seeds (Lactuca sativa), with three types of contaminants (mineral lubricant oil, synthetic lubricant oil and used lubricant oil) for various biodegradation periods in the soil. The toxicity tests indirectly measured the biodegradation of the contaminants. The samples were analyzed at t0, t60, t120 and t180 days of biodegradation. The used lubricant oil was proved very toxic in all the tests and even after biodegradation its toxicity was high.The mineral and synthetic oils were biodegraded efficiently in the soil although their toxicity did not disappear completely after 180 days.

The evaluation soil quality after bioremediation processes solely on chemical data does not include the effects of toxic substances in organisms. Thus, ecotoxicological assays with seeds are applied to assess the effect of toxic substances in organisms according to their germination sensitivity. The objective of this study was to evaluate a contaminated soil with diesel, biodiesel and waste lubricat oil in ecotoxicological bioassays using seeds of Cucumis sativus (cucumber), Brassica oleracea (kale) and Barbarea verna (cress) as test organisms. The sample of contaminated soil was buried to allow contact with microorganisms that are naturally present in the soil and can be capable to biodegrade the contaminant. Each soil sample was removed monthly and the potential toxicity of contaminants was evaluated by examining germination rates according to biodegradation time in soil. The results indicate that the species Barbarea verna is not a good test organism due to its low germination rate. The study suggest that the contact of waste lubricant oil and diesel with the embryo was hampered by the seed coats and the hydrophobicity these substances, preventing the entry of substances which may be toxic to the embryo. Also, Cucumis sativus and Brassica oleracea showed that after two months of biodegradation, biodiesel is the most toxic contaminant during seed development.

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The inhibition of root and hypocotyl elongation may reflect toxic substances in low concentrations, which are not sufficient to prevent germination, but may delay or inhibit root and hypocotyl growth. The objective of this study was to evaluate root and hypocotyl growth inhibition in Cucumis sativus, Brassica oleracea and Barbarea verna as a parameter for assessing soils toxicity when contaminated with diesel, lubricant oil and biodiesel. Thus, potential toxicity of contaminants was evaluated according to biodegradation time in soil by examining root and hypocotyl elongation inhibition. Results show that C. sativus root is the best indicator for diesel and lubricant oil reduced toxicity after biodegradation. It was also observed that biodiesel increases its toxicity after two months of biodegradation.