Effects of environmental concentrations of gadolinium on adults and juveniles of the earthworm Lumbricus terrestris

Rare earth elements (REEs), including gadolinium (Gd), are increasingly released into the environment because of their widespread use in medical imaging, electronics, and renewable energy technologies. Despite growing concerns over their accumulation in soil ecosystems, the effects of Gd on terrestrial organisms are poorly understood. To address this gap, we evaluated the toxic effects of Gd on the soil organism Lumbricus terrestris at both the adult and juvenile stages. Adult earthworms were exposed for 28 days to 1 mg/kg or 10 mg/kg Gd to assess both acute and sublethal effects, including cellular and oxidative stress, neurotoxicity, growth and reproductive performance. The offspring were exposed to 1 mg/kg of Gd for 28 days, followed by an additional 28 days of exposure to 5 mg/kg, and the same sublethal parameters were assessed. The results revealed a low accumulation of Gd in adults and a lack of acute and sublethal effects in Gd-treated worms, except for an increase in lysosomal membrane destabilization. Juveniles were more susceptible, showing increased growth and glycogen content. Upon exposure to Gd, catalase activity was inhibited, whereas acetylcholinesterase activity increased. The effects on glycogen and catalase were exacerbated in juveniles exposed to relatively high Gd concentrations. Overall, the results indicate that L. terrestris is susceptible to Gd exposure, highlighting the need for further research on its long-term effects.