Assessment of Hydrogen Cyanide Emissions from a Tailing Storage Facility of a Gold Mine on Public Health: Findings from a Case Study in Thailand

摘要

This study simulated the emission of HCN from the TSF1 to the communities for the period of 2002 - 2011 under five different pH levels. The simulated results were compared with acute and chronic inhalation RELs of HCN. The results showed that communities living around the mine were likely to be exposed to HCN. The exposure level of the communities to HCN depends on factors like wind direction, terrain elevation, and distance from source to receptor. The pH levels and the allowable concentrations of the total cyanide released to the TSF are two governing factors in exposure assessment. At pH 6.9 in the TSF, forty-two communities were likely to be exposed to acute inhalation RELs of HCN. The simulation showed that the recommended cyanide levels to prevent public health harm should be 2.73 mg/1, not 20 mg/1 as permitted by the environmental and health impact assessment (EHIA) of the mine practiced for more than 14 years. In addition, the results showed that, to governing the volatilization of HCN the EIA report of GM should regulate free cyanide for the permissible limits of cyanide release into TSF instead total cyanide. Additionally, the GM should have a good pH monitoring program for pH to ensure the pH control to be above 10.3 all the time.