Metal and metalloid concentrations in soil, surface water, and vegetables and the potential ecological and human health risks in the northeastern area of Hanoi, Vietnam

Heavy metal and metalloid contamination and related risks for the environment and human health are matters of increasing concern. This study assessed metal and metalloid concentrations in soil, surface water, and locally grown vegetable to assess exposure and related risks for the environment and human health in the northeastern rural area of Hanoi. Concentrations of metals and metalloids in soils exceeded regulatory thresholds in some locations (e.g., Me Linh and Gia Lam districts). The carcinogenic elements As and Cr were identified as a major concern with concentrations up to 693 μg g^-1 and 147 μg g^-1, respectively. Industrial point sources or groundwater irrigation practices in the intensive organic farming areas were identified as potential factors contributing to the accumulation of carcinogenic metals and metalloids in topsoil layers. Metal and metalloid concentrations detected in water and vegetables were below the regulatory threshold levels (WHO guideline and maximum allowable limits). While contamination was not observed at a large geographical scale, local soil contamination in specific areas of agricultural importance could pose high ecological and human health-related risks with unclear long-term impacts. The highly carcinogenic soil contamination detected in this study may be a factor adding to the increased cancer incidence rate in Hanoi area, as the total carcinogenic risk calculated for Hanoi area exceeds the cancer likelihood threshold by a factor of 25. Further research is needed to examine potential links, and the involvement of both stakeholders and policy makers is needed to adequately evaluate the risks for Hanoi area and coordinate future remediation plans if risks are justified.