The Economic Times

In 1997, Sweden used copper-smelting slag beneath a road near Lule; after 10 years, copper, nickel and zinc leaching had declined below recommended thresholds

A decade-long study in Sweden investigated the environmental effects of incorporating copper slag in road construction. The researchers observed a significant reduction in the leaching of metals like copper, nickel, and zinc over time. While initial tests indicated high metal concentrations in various materials, the findings imply that the environmental concerns related to these materials are primarily short-lived.