1 min readPassive Smoking: Plants Can Absorb Nicotine from Soil and Smoke
Braunschweig, Germany — Researchers have found that some plants can actually take up nicotine from cigarette smoke, while others that grow in contaminated soil absorb it via roots as well, explaining why high concentrations of nicotine are often found in spices, herbal teas and medicinal plants.
Previously, nicotine was often used as an insecticide until it was banned by the European Union in 2009 because of its toxicity. Surprisingly, a large number of food crops and plant-derived products still contain very high levels of nicotine. The team of researchers led by Dirk Selmar from the Technical University of Braunschweig, Germany, wanted to find out if there were other reasons at play than the possible illegal use of nicotine-containing insecticides.
They used peppermint plants (Mentha x piperita), which contain minimal traces of nicotine, and mulched their soil with tobacco or fumigated the plants with cigarette smoke. “Tremendously elevated nicotine levels were detected after fumigation with cigarette smoke,” notes Selmar.
In addition, the team also found that peppermint plants are actually able to absorb nicotine from contaminated soils. Plants in the study were mulched with cigarette tobacco for more than nine days and subsequently analyzed. The resulting nicotine concentrations were several times higher than the maximum residue level set by the European authorities. It is the first study that reveals that the reported high levels of this substance in food plants may indeed originate from tobacco.
As time progressed, the researchers found a drastic decrease in nicotine concentration in peppermint leaves. This is likely because the nicotine is taken up by the roots of the peppermint plants and then processed in their leaves.
Our results suggest that the widespread occurrence of nicotine in medicinal, spice and food plants may, at least in part, be due to other nicotine sources apart from the illegal use of insecticides,” says Selmar.
In addition to the significance for the food industry, these results have a tremendous relevance for basic science: they prove that substances, such as alkaloids, can be transferred from one plant, after its death, to another. Such “horizontal transfer of natural products” sheds light on the yet unexplained success behind farming practices such as crop rotation and the co-cultivation of certain vegetables.
Article adapted from a Springer news release.
Publication: Nicotine uptake by peppermint plants as a possible source of nicotine in plant-derived products. Selmar D et al. Agronomy for Sustainable Development (April 7, 2015): Click here to view.