Concentrations of heavy metals and associated human health risk in unrefined salts of inland hypersaline lakes, Egypt

This work investigates the heavy metal concentrations in Siwa Oasis and Wadi El Natrun unrefined salt. Sixteen samples were examined for the concentration of Cd, Co, Cr, Cu, Ni, Pb, V and Zn using inductively coupled plasma-optical emission spectrometer (ICP-OES). In addition, the major ions and mineralogical composition were investigated using X-Ray fluorescence (XRF) and X-ray powder diffraction (XRD) techniques. The result revealed that Wadi El Natrun salt contained an elevated concentration of these heavy metals when compared to those of Siwa Oasis and worldwide. Both non-carcinogenic and carcinogenic risk indicators for Siwa Oasis salt were lower than the acceptable levels; hence, consumption of these salts may not pose any significant human health risks. On the contrary, human health risk indicators values for Wadi El Natrun salt were higher than the acceptable levels; suggesting the consumption of this salt may be hazardous and can severely affect human health. The authors strongly recommend that the usage of Wadi El Natrun salt should be limited to industrial applications only.