This study evaluated the acute toxicity of three tyre-derived chemicals—DPG, MBT, and 6PPD-Q—on the marine diatom Phaeodactylum tricornutum. DPG was most toxic (EC50 = 0.101 µg/L), followed by MBT and 6PPD-Q. Results show significant growth inhibition, with MBT and DPG toxic at environmentally relevant levels.

DPG and MBT significantly inhibited growth of Phaeodactylum tricornutum at concentrations commonly found in urban waters, highlighting serious ecological risks. 6PPD-Q showed moderate toxicity with a potential hormetic effect. These findings emphasize the need to reassess environmental safety thresholds for tyre-derived pollutants.