Estimation of metal(oid)s oral and inhalation bioavailability in synthetic and recycled rubber materials and artificial turf using a dialyzability-based In-Vitro approach

Synthetic/recycled rubber materials are widely used in playgrounds, artificial turf infill, and synthetic tracks, but they may contain harmful substances, such as metal(oid)s, posing health risks through ingestion and inhalation. The use of such materials and artificial turf has raised increasing concern, and several studies have begun to investigate the pollutants potentially released into simulated fluids ( in-vitro bioaccessibility) to provide a more realistic assessment of the associated health risks. In this context, the present study reports, the estimation of the oral and inhalation bioavailability of metal(oid)s (bioaccessible fraction that can potentially be absorbed into the bloodstream and pose a major health risk) in synthetic/recycled rubber materials and artificial turf, from public facilities and brand-new samples. To this end, an in-vitro oral and inhalation bioavailability approach was applied using synthetic human fluids and dialysis membrane filled with simulated human plasma to mimic absorption, with subsequent metal(oid)s quantification. Higher inhalation bioavailability ratios (1.0 – 37.4% for Mo and Rb, respectively) were observed compared to oral ones (0.35 – 22.7% for Fe and Sr, respectively). Regarding the rubber composition, samples made of ethylene propylene diene monomer showed higher metal(oid)s bioavailability ratios than those made of styrene-butadiene-styrene, suggesting distinct metal(oid)s-polymer interactions influencing their release. Non-carcinogenic and carcinogenic hazard indexes via ingestion and inhalation were assessed using metal(oid) oral and inhalation bioavailable concentrations based on the California Office of Environmental Health Hazard Assessment exposure model. The results suggested no significant carcinogenic or non-carcinogenic risks for several scenarios, including children, adults, coaches, and bystanders from both exposition routes. • Bioavailability of metals via oral/inhalation was assessed using simulated dialysis • Oral bioavailability ratios higher than 10% were found for Mn, Ni, Sb and Sr • Inhalation bioavailability ratios higher than 20% were found for Sb, Sr and Rb • High inhalation bioavailability for all metals vs. oral, except Ni and Sr • Health risks for rubber-bound metals via oral/inhalation suggests no risk to human