Most people are familiar with the idea of farm-to-table dining. But what about road-to-table cooking? A new study from the University of Vienna has shown that lettuce easily absorbs particles produced by car tires when driving. The research is another evidence that everyday materials, such as plastic bottles or medicines, can reach food, although their (potentially harmful) effects on the body are still unknown in detail.
It is known that as tires rub against the road they produce microscopic wear particles. And they are not few, since research indicates that they reach the environment around 1 kg per person per year. And sure, they can find their way onto farmland via atmospheric deposits, road runoff, or sludge from sewage treatment plants that farmers use as fertilizer. There is data on the latter: 93% of these particles remain in after passing through these treatment plants, to the point that between 1,400 and 2,800 tons end up each year on agricultural land (only in Germany).
Previous research at the University of Vienna had shown that many of these particles released pollutants into the upper levels of the soil, but now they wanted to know what would happen if the chemicals went lower. Could they be absorbed by plants through their roots?
To find out, they decided to place lettuce plants in a hydroponic solution to which five tire-based contaminants were added. And their measurements showed that the lettuce plants took all the compounds we investigated through their roots, transferred them to the lettuce leaves, and accumulated them there. The researchers note that not all of the compounds tested have yet been shown to be toxic, save one: 6PPD-quinone, which has been linked to mass salmon die-offs in the US Pacific Northwest.
The team also experimented with adding tire crumbs to the water and found that the lettuce plants still took up the contaminants. In addition, the plants metabolized the chemicals into novel substances. “The plants processed the substances and, in doing so, produced compounds that had not been described before,” says Thorsten Hüffer, CMESS Principal Scientist. “Since we do not know the toxicity of these metabolites, they represent a health risk that cannot be assessed until now.”
The researchers point out that these chemicals are stable in plants, but could be unlocked by eating, since these compounds are broken down very easily in the human body. In the next phase of the research, the team will experiment with plants placed in the ground to see how they interact with tire particles.
Via: Environmental Science & Technology
Source: University of Vienna
