Microplastics have long found their way into our food. For example, if fish eat the small particles, they end up on our plates. Scientists led by environmental scientist Thilo Hofmann from the Center for Microbiology and Environmental Systems Science at the University of Vienna have now also discovered toxic substances from car tire wear in lettuce.
Wind, sewage sludge and wastewater carry the tire particles to the fields, where the pollutants they contain can end up in the vegetables.
In their study, which was published in the journal “Environmental Science & Technology,” the researchers 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.
“Unpredictable health hazard”
“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.
Car tires are an important source of microplastics that pollute the environment. 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. According to the study, the extent of tire particulate emissions is still poorly quantified. (SDA/hei)