Cyanide is used to extract gold from gold-bearing ore, resulting in wastewater containing cyanide compounds which is released to a tailing storage facilities (TSF). Hydrogen Cyanide (HCN) is highly volatile and the most toxic form of cyanide. A large gold mine in Phichit Province, Thailand uses cyanide to extract gold from ore, and cyanide contaminated waste product is released into a TSF, which is allowed to have a maximum cyanide concentration of 20 mg/l. There is great concern whether airborne HCN emissions from TSF pose a public health hazard. To assess the effect of HCN emissions from TSF on public health, the AERMOD model was used to simulate the dispersion of HCN from the mine’s TSF. The simulated results were compared with acute and chronic inhalation Reference Exposure Levels (RELs) for HCN. The results show that communities living around the mine were likely to be exposed to HCN. At pH in the TSF, forty-two communities were likely to be exposed to acute inhalation RELs of HCN, and 2 communities exposed to chronic effect. The simulation showed that the recommended cyanide levels to prevent public health harm should be mg/l, not 20 mg/l as permitted by the environmental and health impact assessment (EIA) of the mine. |
