Ecological and health risks assessment of potentially toxic metals and metalloids contaminants: A case study of agricultural soils in Qatar

Abstract

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. In recent years, Qatar has witnessed exponential growth in the human population, urbanization, and increased anthropogenic activities, including agriculture. Potentially toxic environmental contaminants, including metals and metalloids, are commonly found in emerging economies. At high concentrations, elements such as As, Cr, and Ni can be hazardous and may lead to various health problems in humans, including cancer. The current study measured As, Cd, Cr, Cu, Ni, Pb, V, and Zn concentrations in agricultural soils. Pollution levels and potential negative impacts on human and environmental health were determined using the United States Environmental Protection Agency (USEPA) standard methodologies. According to the study’s findings, the studied element concentrations descended in the following order: Zn > Cr > V > Ni > As > Cu > Pb > Cd. Of these, As (27.6 mg/kg), Cr (85.7 mg/kg), Ni (61.9 mg/kg), and Zn (92.3 mg/kg) concentrations were higher than average world background levels. Each of these elements also had an enrichment factor (EF > 1), indicating their anthropogenic origin. The combined pollution load index (PLI > 1) and geo-accumulation index (Igeo) range values of -0.2-2.5 further indicated that the soil was up to 58% polluted. However, the ecological risk factor (Er ≤ 40.6) and potential ecological risk index (PERI = 79.6) suggested low ecological risk. A human health risk evaluation showed that only As, with a hazard index (HI) of 1.3, posed a noncarcinogenic risk to infants. Additionally, As, Cr, and Ni, with total carcinogenic risk (TCR) values of 1.18 × 10-4 and 2.06 × 10-4 for adults and children, respectively, proved carcinogenic to both age groups. The elements’ carcinogenic risk (CR) potential descended in the following order: Ni > As > Cr. Additionally, for both adults and children, oral ingestion is the most likely exposure pathway. Our findings support the need for closer monitoring of potentially toxic metals and metalloids levels in cultivated soils and farm produce in Qatar. Reducing the elements’ bioavailability in soil and developing innovative remediation technologies is needed to limit potential risks to human health. Further studies on As, Cr, and Ni gastrointestinal bioaccessibilities are needed to fully understand the effects after long-term exposure and the cancer-causing potential of these elements over a lifetime.