Researchers detect toxins from tire wear in lettuce

In a study, researchers discovered toxic additives from rubbing car tires into lettuce. Wind, sewage sludge and wastewater carry the tire particles to the fields, where the pollutants they contain can end up in the vegetables.

As the scientists have shown in experiments, lettuce plants absorbed all five of the chemicals studied, some of which were highly toxic. Their study was published in the journal “Environmental Science & Technology”.

Car tires are an important source of microplastics that pollute the environment. The magnitude of tire particle emissions is still poorly quantified, the scientists surrounding environmental scientist Thilo Hofmann of the Center for Microbiology and Environmental Systems Science at the University of Vienna write in their work. As they write in a statement, about a kilogram of tire particulates per capita per year is blown into the environment with the wind and washed into rivers and sewers by rain.

In their study, the scientists conducted several experiments to investigate whether edible plants absorb the pollutants. To do this, they added five chemicals used in tire production to the nutrient solutions of lettuce plants in the laboratory.

“Our measurements showed that the lettuce plants took up all the compounds we examined through the roots, transferred them to the lettuce leaves and accumulated there,” says Anya Sherman of Hofmann’s team. This uptake also occurred when the lettuce plants were not exposed to the chemicals directly, but indirectly via tire granules in the root area.

The researchers also identified those substances formed from the chemicals absorbed during the plant’s metabolism. These metabolites are compounds that have not yet been described, the toxicity of which is unknown and therefore “present an unpredictable health risk”, emphasizes Thorsten Hüffer of Hofmann’s team. (aeg/sda/apa)