Toxicity of Biodiesels

With the growth of industrialization and increased need for energy, there has been major reliance on the burning of fossil fuels, resulting in a multitude of environmental issues.  Determining alternatives to fossil fuel sources is essential to limit pollutants into the environment, giving rise to the need for biodiesels. Biodiesels are fuels that are created from sustainable sources, generate low greenhouse gas emissions, and cause less harm to the surrounding environment due to their reduced toxicity as compared to other fuels or diesels. In determining viable and effective biodiesel options, it is important to assess many of their properties, including their relative toxicity levels to determine options that minimize environmental harm and degradation.

In Environmental Chemistry Lab, the toxicity of various biodiesels and fuels was tested to determine which caused the least harm to the growth of radish plants. This analysis is important as the impacts of fuel toxicity to humans, plants, and animals must be considered in the evaluation of viable biodiesels. It has been found that biodiesels are much less toxic than diesel fuels and are readily biodegradable, making them an attractive option for replacement of current fuels. This also means that biodiesels are less likely to harm the environment in the case of accidental oil spills, making for a less costly cleanup process.

The toxicity analysis in lab consisted of growing radish seeds in various fuel types of multiple concentrations mixed into water. The results supported that the toxicity of biodiesels is lower than that of other fuels as the ethanol, butanol, and USD diesel that were tested each had the lowest percent germination and smallest amount of growth for the radish seeds as shown in the graph below. For the biodiesels tested which included the La Paloma waster oil, olive oil, and Wesson canola oil, the percent germination and average growth length of the plants were much higher than the other fuels. As the concentration of the fuels in water increased, ethanol and butanol greatly reduced the percent germinated and average growth length of the radish seeds, while the biofuels had much higher percent germination and growth length.

Our results support that biodiesels are less toxic than regular fuels and diesels. This is because biodiesels are derived from vegetable oils, making them naturally non-toxic. For example, the LD50 value, or the lethal dose required to kill 50% of the sample population via oral consumption, for biodiesel is greater than 17.4g/kg. For comparison, table salt has an LD50 of 3.0 g/kg, making it 6 times more toxic than biodiesel. Further, the LD50 of diesel is 7.5g/kg, showing its increased toxicity as compared to biodiesel.

Continuing to determine viable sources of biodiesels will be important to sustainably meeting the energetic demands of modern society, while also minimizing harm to the environment. As compared with regular fuels, biodiesels are less toxic to the environment, making them a greener, more sustainable option for fuel.

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