Study reveals car tyre chemicals found in leafy greens

The researchers highlighted that the concentrations of tyre additives in vegetables were comparable to those of drug residues.

A recent study has revealed that chemical additives from car tyres are making their way into leafy greens, potentially impacting food safety. The research, conducted by the Centre for Microbiology and Environmental Systems Science at the University of Vienna and the Hebrew University of Jerusalem, was published in the journal Frontiers in Environmental Science, New York Post reported.

Researchers identified that these chemicals enter agricultural systems through atmospheric deposition, meaning they travel via precipitation and accumulate on plants. Additionally, leafy greens absorb these additives through irrigation with treated wastewater and the use of sewage sludge as fertiliser.

Thilo Hofmann, head of the research group, emphasised the potential human health risks: "There they can be taken up by plants and thus also reach humans," he stated in a press release.

Car tyres contain a variety of substances designed to enhance durability and performance. Of these, 5 percent to 15 percent are chemical additives, which ultimately find their way into our food supply. "The toxicity of tyre and road wear particles is related to their organic additives and associated transformation products," explained Anya Sherman, a Ph.D. student at the Centre and the study's lead author.

The research team analysed vegetable samples from supermarkets in Switzerland and field vegetables from Israel to assess the presence of these additives. "We examined real samples from supermarkets in Switzerland and field vegetables from Israel," Hofmann noted.

The Swiss vegetables, sourced from Italy, Spain, and Switzerland, and the Israeli field vegetables, were tested for tyre additive concentrations. While the levels found were low, they were still detectable. The daily intake of these chemicals, depending on diet, ranged from 12 to 1,296 nanograms of benzothiazole and 0.06 to 2.6 nanograms of 6PPD, the latter being toxic to certain fish like coho salmon.

The researchers highlighted that the concentrations of tyre additives in vegetables were comparable to those of drug residues, which previous studies have also found in leafy greens. "While the concentrations and daily intake are fortunately relatively low, additives from car tyres are still found in food. That’s not where they belong," Hofmann commented.

Hofmann stressed the need for further research to fully understand the implications of these food additives on human health and the environment. This study builds on earlier findings from 2023, which first demonstrated the potential for plants to absorb car tyre additives. Sherman added, "The question was whether this only happens in our mechanistic laboratory study or also in the field."