Determining the reuse of metal mine wastes based on leaching test and human health risk assessment

Meeting the regulations based on the short-term leaching tests may not necessarily assure the environmental and human health safety of reusing mine wastes. This study investigated heavy metal leachability of four metal mine waste samples (e.g., Z, Y, H, and M) and human health risk of reusing them as construction materials. The heavy metal leachability did not depend on the total heavy metal contents. For example, the Z sample contained greater amounts of As and Fe than Zn, but the leachates contained only Zn at a detectable level. This can be attributed to the crystalline structure and heavy metal fractions of the mine wastes. The leaching test results suggested that the four mine waste samples are potentially reusable. But the Z and M samples reused in industrial areas imposed carcinogenic risks. This was largely attributed to As that is exposed via dermal contact. The Y and H samples reused in residential areas imposed carcinogenic risk. The major exposure route was the ingestion of crops grown on the mine wastes and Cr was the major concern. The two-stage assessment involving leaching tests and risk assessment can be used to promote safe reuse of mine wastes.