The presence of toxic metals in tillage soils of Chittagong hill tracts in Bangladesh and the resultant health risk

In the last few decades, the unplanned use of the land of Chittagong Hill Tracts (CHT) may result in toxic heavy metal contamination of the tillage soil, hence pose a greater risk to the health of indigenous peoples. Therefore, this study was conducted to assess the concentration of toxic metals in soils of the CHT area by using an atomic absorption spectrometer. The degree of contamination of soil was evaluated using five indices: geo-accumulation index (I-geo), enrichment factor (EF), contamination factor (CF), pollution load index (PLI), and potential ecological risk index (PERI). The calculated I-geo for all metals indicates a category of moderately polluted, while EF indicates a moderate enrichment. The calculated PERI data indicate a considerable ecological risk posed by Cd metal. According to these criteria, these soils can be classified as moderately contaminated with some metals. Furthermore, the identification of pollution sources based on principal component analysis and hierarchical cluster analysis has revealed that all analysed metals are anthropogenic except Fe. The calculated hazard index of >1 indicates the potential chemical risk, mostly due to the high value of Fe. Carcinogenic risks through the ingestion, inhalation and dermal pathways show a non-significant risk (CR<10(-6)) for both children and adults. Measured data may help policymakers to reduce the potential effects of soil contamination on the eco-environment and human health.