This study was based on the serious concern over toxic metal pollution arising from atmospheric pollution. The basic objective of the study was to evolve baseline information and data regarding hair metal levels in donors selected with the multiple objectives to evolve the dependence of hair metal levels on their age, sex, occupational exposure and geographical location. To this end, possible use of multivariate statistical analyses for identification of sources of metals in hair and the possibility of use of hair metal analysis for clinical purposes was also explored. This study, therefore, was conceived to evolve hair metal database for use in futuristic programs towards abatement of toxic metal impacts on human health, and to add new data resource for this part of the world. In total, 1643 hair samples were collected from different segments of local population that comprised both rural and urban, traffic police personnel, metal arc welders, cerebral palsy patients and mentally retarded persons. Eighteen metals (Ag, Au, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sb, Sr and Zn) were estimated in the collected hair samples by the wet digestion method (HN03 / HCI04) using flame atomic absorption spectrometry (FAAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES).
Levels and sources of selected metals in the hair of male and female donors were found different for different age groups. The 20-40 year age group showed relatively enhanced levels of Ca, Mg, Zn and Fe, while trace metals showed enhanced tendency to accumulate in the hair of elderly donors. The principal component analysis and cluster analysis evidenced food, water, medicinal supplements and environment as major sources of metals in the hair of selected donors. The study segment on the occupational exposure revealed that traffic police were at a high risk of Pb and Cr exposure and more than 80% of the personnel showed hair lead levels greater than the safe reference levels of the metals laid down by world health authorities. Similarly, the metal arc welders were found to be at risk of cumulative toxic effects of vehicular emissions and welding fumes. Also, the levels of Cr turned out to be comparable in the hair of traffic police personnel and metal arc welders. The study on the metal dysfunction aspect showed that the levels of Fe, K and Cu were lower while those of Cr, Ag and Cd were higher in the hair of cerebral palsy patients as compared with controls, probably because the body metabolism in cerebral palsy patients affected the Mg and Sb levels in their hair. Statistically, the selected metals were normally distributed in the hair of cerebral palsy patients as opposed to mentally retarded donors. In the other segment of the dysfunction study, the high level of Mn in the hair of mentally retarded persons was found to be linked with mental retardation. On the whole, the distribution of metals in the pooled hair data was found to be random and divergent.
The alkaline earth metals (Ca, Mg and Sr) in hair were found positively correlated with each other in all donor groups, with certain positive mutual correlations. The Pearson correlation coefficient values were 0.47, 0.52 and 0.63 for Ca-Sr, Ca-Mg and Mg-Sr pairs respectively in this case. Similarly, Na and K were mutually and positively correlated at r = 0.47. Most of the local donors were found to have normal levels of Ca, Cd, Cu, K, Li and Sb while majority of the donors showed high levels of Na, Sr, Mg, Cr and Co in their hair. In comparison with the literature reference levels of metals in hair, all studied donors showed high levels of Na and Sr and about 50% of the donors exhibited higher levels of Mg, Cr, Co, Ni and Pb. The physiologically important metals Fe and Zn showed lower levels in about 35% of the studied population segments. The Ca levels in the hair of Pakistani donors were comparable with those reported for donors from USA, Iran and Brazil. Further, the Cu levels in the hair of Pakistani and Iranian donors were found comparable, but these were lower compared with levels reported for donors from USA and Brazil. The levels of all other selected metals in the hair of Pakistani donors were much higher as compared with counterpart levels from other parts of the world. Overall, the present study evidenced a fast deterioration of local environment that was subjected to severe trace metal pollution stress, and people from all walks of life were adversely affected by the ever-expanding metal pollution scenario in the country.