Human biomonitoring of trace metals from different altitudinal settings of Pakistan

Abstract

Human bio-monitoring (HBM) and assessing the body burden of potentially toxic trace elements is of critical importance for Public health. Thus, appropriate selection of bio-marker to consider broad spectrum of encountered environmental contaminants is of great importance. The current study aims to access the potentially toxic level in trace metals, Cadmium (Cd), Cobalt (Co), Chromium (Cr), Copper (Cu), Manganese (Mn), Nickel (Ni), Lead (Pb) and Zinc (Zn) and were assessed by inductively coupled plasma mass spectrometry (ICP-MS) in nail and hair samples (N = 178, N = 180 respectively). Samples were taken from four different ecological zones of Pakistan which include frozen mountain zone (FMZ), wet mountain zone (WMZ), riverine delta zone (RDZ) and low-lying zone (LLZ). A total of 134 male and 46 females between 15-40 years of age participated. Hair analysis showed higher concentration of Zn (281.15 ppm), Co (0.136 ppm) and Mn (5.65 ppm) in FMZ, Cr (1.37 ppm), Mn (7.83 ppm) and Ni (1.22 ppm) in WMZ, Co (0.15 ppm), Mn (11.89 ppm) and Ni (0.99 ppm) in RDZ, Mn (8.99 ppm) and Ni (0.90 ppm) in LLZ. While in case of nails Mn (9.91 ppm) in FMZ, Mn (9.38 ppm) and Ni (10.69 ppm) in WMZ, Mn (24.03 ppm) and Ni (8.89 ppm) in RDZ, Mn (12.46 ppm) and Ni (12.59 ppm) in LLZ showed higher concentration. Overall most abundant toxic trace element were Mn and Ni (Mn > Ni) in both hair and nail samples exceeded the WHO prescribed tolerable guideline (Mn; 0.63-3.3, Ni; ≈6). In general, in case of hair, elevated trace metals from different districts of Pakistan were generally found higher in mountainous zones (i.e., FMZ and WMZ) whereas in nails, elevated metal levels were observed in RDZ and LLZ zones. Spatial analysis for trace elements concentrations revealed that metal levels in hair tend to increase with increasing latitudes as well as increasing longitudes except Mn. Furthermore, trace metals in nail samples tend to decrease at higher latitudes and longitudes, except Zn, which showed opposite behavior.Estimated daily intake showed that dust and food had the highest contribution to Pb and Zn in all zones. Whereas, for Mn, Co, Cr, Cu and Cd, water act as main exposure medium.