When playing in sandboxes, children are particularly vulnerable to poisoning with potentially toxic elements (PTE) due to their hand-to-mouth behaviour. In Slovenia, the city of Celje is heavily contaminated due to zinc ore smelting and iron industry. In some sandboxes, sand from Mežica Pb-Zn mine waste was used. Granulometric and XRF analysis showed that all samples contain larger percentage of fine-sized particles and some have higher As, Ba, Cd, Pb and Zn contents than allowed. By XRD and SEM/EDS analysis we identified carries of PTE, and confirmed three possible sources of contamination: the waste material from the Pb-Zn mine, the emissions from local industry and from the old Zn-smelting stockpile used as a landfill. The total health risk (ΣHI) exceeds critical value in one sandbox. The bioaccessibility of PTEs is alarming due to presence of highly soluble metal-bearing particles. Study revealed importance of combining results of health risk evaluation with bioaccessibility of elements, which is a function of the carriers of PTE. This knowledge is essential for undertaking remedial measures. Improper use of waste material could result in introducing hazardous material in the environment. We propose frequent replacement of sand and stricter legislation regulating status and usage of waste materials. Display omitted •Playground sandboxes and nearby soils are contaminated with PTE.•PTE sources are mine waste used as sand and local Zn-smelter stockpile resuspension.•PTE carriers are Pb-Zn ore minerals, Zn-smelting slag and pigments.•Improper reuse of mine waste material is important contamination source.•health risk indices are low, but high PTE bioaccessibility is of great concern.