Plants too are passive smokers

Passive smoking is not only bad for family and friends but also for plants around us that can take up nicotine from contaminated soils as well as from smoke, a significant research reveals.

While some plants are actually able to take up nicotine from cigarette smoke, others that grow in contaminated soil absorb it via roots as well.

"This might explain why high concentrations of nicotine are often found in spices, herbal teas and medicinal plants, despite the fact that nicotine is no longer permitted in insecticides," explained Dirk Selmar from the Technical University of Braunschweig, Germany.

For the study, the team used peppermint plants which contain minimal traces of nicotine, in a series of mulching and fumigation experiments.

"Tremendously elevated nicotine levels were detected after fumigation with cigarette smoke," Selmar noted.

He also found that peppermint plants can actually take up high concentrations of nicotine from contaminated soils.

This followed the analysis of plants mulched with cigarette tobacco for more than nine days.

The resulting nicotine concentrations were several times higher than the maximum residue level set by the European authorities.

"The research reveals that the reported high levels of this substance may indeed originate from tobacco," the authors concluded.

The team found a drastic decrease in nicotine concentration as time progressed.

This is likely because the nicotine is taken up by the roots of the peppermint plants and 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," Selmar emphasised.

In addition to the significance for the food industry, these results have a tremendous relevance for basic science: they prove that substances such as nicotine (an alkaloid) can be transferred from one plant, after its death, to another.

The findings were published in Springer's journal Agronomy for Sustainable Development.