Challenges in Assessing the Environmental and Human Health Risk Associated with Sulfide Tailings

In this paper, the challenges associated with the assessment of environmental and human health risk for two high sulfur tailings (HST), produced after flotation of sulfide ores in Finland, are highlighted and discussed. First, chemical and mineralogical analyses of the tailings are performed using an X-ray fluorescence energy dispersive spectrometer (XRF-EDS) and an X-ray diffractometer (XRD). For the risk assessment study the following tests are used (i) the EN 12457-2 and Toxicity Characteristics Leaching Procedure (TCLP) which assess the leaching rate of potentially harmful elements (PHEs) present in the tailings, (ii) the pH dependent test which assesses the leaching behavior of the main elements over a wide pH range and (iii) the sequential extraction procedure (SEP) which determines the exchangeable and other fractions of PHEs. For the assessment of human health risk the in vitro Physiologically Based Extraction Test (PBET) that simulates the gastric and intestinal tract and determines the bioaccessible fraction of PHEs that are readily available for uptake by humans through ingestion is used. Health risk indicators including carcinogenic risk (CR) and hazard quotient (HQ) are also calculated. The results indicate that (i) the environmental risk for most PHEs is relatively low due to the implementation of well-designed tailings disposal practices at both sites, and (ii) CR slightly higher than 10 − 4 and HQ less than 1 are calculated under the worse-case scenario, indicating no actual adverse effects for adults and children.