Bioaccessibility of organic compounds associated with tire particles using a fish in vitro digestive model: solubilization kinetics and effects of food co-ingestion

Abstract

Tire and road wear particles (TRWP) account for an important part of the polymer particles released into the environment. There are scientific knowledge gaps as to the potential bioaccessibility of chemicals associated with TRWP to aquatic organisms. This study investigated the solubilization and bioaccessibility of seven of the most widely used tire-associated organic chemicals and four of their degradation products from cryogenically milled tire tread (CMTT) into fish digestive fluids using an in vitro digestion model based on Oncorhynchus mykiss. Our results showed that 0.06% to 44.1% of the selected compounds were rapidly solubilized into simulated gastric and intestinal fluids within a typical gut transit time for fish (3 h in gastric and 24 h in intestinal fluids). The environmentally realistic scenario of coingestion of CMTT and fish prey was explored using ground Gammarus pulex. Coingestion caused compound-specific changes in solubilization, either increasing or decreasing the compounds’ bioaccessibility in simulated gut fluids compared to CMTT alone. Our results emphasize that tire-associated compounds become accessible in a digestive milieu and should be studied further with respect to their bioaccumulation and toxicological effects upon passage of intestinal epithelial cells.

Tyre particle exposure affects the health of two key estuarine invertebrates

“…Tyre particles leach a cocktail of trace metals and organic pollutants (Halsband et al, 2020), which may cause digestive cell loss. In this present study, we were not able to discriminate between any effects of leachates as compared with the tyre particles themselves, although studies by Masset et al (2021Masset et al ( , 2022 found that heavy metals and organic compounds leach from the tyre particles into the gastrointestinal fluids of fish, backing up this theory.…”

“…Aquatic exposure affects growth and swimming behaviour in estuarine species; the springtail Menidia beryllina and the mysid shrimp Americamysis bahia (Siddiqui et al, 2022). As well as the physical effects caused by ingestion of particles, tyre wear particles can exert chemical effects through leaching of a cocktail of organic additives and metals into the surrounding water column and sediments (Halsband et al, 2020), or directly from the particles into the gastrointestinal fluids or organisms, as has been observed in fish (Masset et al, 2022;Masset et al, 2021). Leachates, with the particles removed, have proved lethal to marine copepods with an LC 50 of 35 g.L − 1 for Calanus sp.…”

The invisible footprint of climbing shoes: high exposure to rubber additives in indoor facilities

“…Overall, RDC concentrations in shoe sole samples were highly variable and likely due to different compounding strategies used by manufacturers as well as the target product characteristics (i.e., stiffness, durability, performance, adhesiveness). RDC concentrations in shoe sole samples were generally lower (DPG and PPDs) or similar (benzothiazoles) to those in tire tread 51,52 but higher than in other elastomeric consumer products 52 .…”

“…These results suggest that, as in other rubber products, 2SH-BTZ is used as a vulcanization accelerator during the curing process. Other benzothiazoles are also present and are typically considered to be impurities or degradation products 51,52 . Unlike benzothiazoles, DPG and aniline were not detected in every shoe sole sample, with concentrations ranging from <LOQ to 814 µg/g and <LOQ to 225 µg/g, respectively.…”