Effects of tire particles on earthworm (Eisenia andrei) fitness and bioaccumulation of tire-related chemicals

Tire and Road Wear Particles (TRWP) are produced during the wear of tire rubber on the road pavement and contain various chemicals originating from the road environment and from the rubber. Toxic effects of TRWP and their associated chemicals on soil organisms remain poorly characterized. In a series of laboratory experiments, this study investigated the bioaccumulation kinetics of several common tire-related chemicals in the earthworm species Eisenia andrei using Cryogenically Milled Tire Tread (CMTT), as a surrogate for environmental TRWP. Effects on survival, growth, reproductive output and behaviour were determined. Average biota-soil accumulation factors ranged from 0.8 to 4.7 indicating low to moderate bioaccumulation of the tire-related chemicals. Toxicokinetics showed both high uptake (0.0–13.2 days−1) and elimination rates (0.0–6.3 days−1) in E.andrei. Still, the uptake of tire-related chemicals in earthworms' tissues and ingestion of tire particles could lead to trophic transfer to preys feeding on earthworms and requires further investigated. No significant effects on survival and growth were recorded after exposure to 0.05 and 5% CMTT. In the reproduction test, a slight increase of the reproductive output with increasing CMTT concentration and a slight decrease of the weight of the juveniles were observed. Moreover, a strong and significant avoidance behaviour was observed for worms exposed to 5% CMTT. This work highlights that soil highly contaminated with tire particles can negatively impact habitat function due to changes in texture and/or chemical stressors, lead to uptake of tire-related additives by earthworms and that high concentrations can impact organism's fitness.