Toxic and heavy metals contamination assessment in soil and water to evaluate human health risk

TLDR

Urbanization and industrialization have increased solid waste generation, leading to leachate leakage from landfills that contaminates soil and groundwater and poses serious human health risks. The study aimed to determine the composition of toxic metals (Cr, Mn, Cu, As) and heavy metals (Cd, Ba, Hg, Pb) in soil and water. The authors used inductively coupled plasma optical emission spectrometry (ICP‑OES) with certified reference materials (SRM 2709a and SRM 1640a) to ensure accurate measurement and recovery of the metals. Metal concentrations were generally below EU, WHO, and US EPA limits except Cu and Pb, with soil contamination ranging from uncontaminated to moderate; children received higher average daily doses and higher hazard quotients, particularly for inhalation, while adults had higher dermal exposure; hazard indices for Cr and Pb were 7–7.5 times higher in children, and the lifetime cancer risk for Cr approached the borderline risk level.

Abstract

Due to urbanization and industrialization, there has been an increase in solid waste generation and has become a global concern and leakage of leachate from landfills contaminate the soil and groundwater and hence can have a severe impact on human health. The present study aimed to determine the composition of toxic metals (Cr, Mn, Cu, As) and heavy metals (Cd, Ba, Hg, Pb) in soil and water by an inductively coupled plasma optical emission spectrometer (ICP-OES). To ensure accuracy during the analysis of Cr, Mn, Cu, As, Cd, Ba, Hg, and Pb in real samples, certified reference material (CRM, SRM 2709a) of San Joaquin soil and water (SRM 1640a) were analyzed and results were presented in terms of % recovery studies. The mean concentration of all the metals in soil and water did not exceed the limit set by the European Community (EU), WHO, and US EPA except Cu where the permissible limit defined by the EU is 50-140 mg/kg in soil. The soil is uncontaminated to moderately contaminated with respect to all metals except the Cu and Pb. Among the average daily dose (ADD) of soil, ADDing and ADDinh for children had the maximum dose for all metals than adults while ADDderm was higher in adults. Hazard quotient (HQ) trend in both adults and children was found in order HQing > HQderm > HQinh of soil for all metals except Ba which followed HQing > HQinh > HQderm. Hazard index (HI) values of soil for Cr and Pb in children were 7 and 7.5 times higher than adults respectively. Lifetime cancer risk (LCR) value for Cr by different exposure pathways of soil was 5.361 × 10-4 for children which are at the lower borderline of risk for cancer.