Part of the playground at a Bristol nursery school has been fenced off after landfill materials were found.
The materials, unearthed at St Werburgh's Park Nursery School, date back to before the site was built in the 1930s.
They include industrial 'clinker', which contains arsenic, as well as metals such as lead and zinc.
Council safety manger Bill Crocker said: "The health risk presented by the landfill is very small."
The council says the materials, which were unearthed during work over the summer holidays, are typical of those found in areas previously used for industrial activities.
It said it would be removing the landfill "as swiftly as possible."