Are there chemicals from tires in lettuce?
To our knowledge, no studies have been published to date that have found TRWP or tire-related compounds in farmland soil and available for uptake by lettuce. A study by Castan et al., 2023 into the potential for uptake of tire-related chemicals in lettuce purposefully spiked a non-soil growing-medium with chemicals at unrealistic amounts that the authors acknowledged were much greater than those measured in the environment.
The suitability of the study approach has been called into question. Castan et al., 2022 grew lettuce hydroponically, whereas the rationale for the study was that tire and road wear particles (TRWP) might be deposited onto farmland soil by application of biosolids as a fertilizer and subsequently leach tire related chemicals into the soil. To our knowledge, no studies have been published to date that have found TRWP in farmland soil or that tire related compounds are present in farmland soil as a result of leaching from TRWP.
A recent Ktipp consumer-testing report that detected tire-related chemicals in salad was not published in scientific peer-reviewed literature, which makes its claims – including the sources of any found chemicals – impossible to validate.