Quantification and risk assessment of heavy metal build-up in soil-plant system after irrigation with untreated city wastewater in Vehari, Pakistan.

In peri-urban areas of district Vehari, farmers are using untreated city wastewater for crop irrigation owing to the scarcity of good-quality irrigation water. This practice may pose severe environmental and health issues to local inhabitants attributed to the high levels of potentially toxic metals in wastewater. The present study evaluated the potential impacts of wastewater irrigation on metals (Cd, Cr, Cu, Fe, Ni, Mn, Pb and Zn) build-up in the soil-plant continuum and associated health risks. In this study, wastewater (n = 17), soil (n = 108) and plant (n = 65) samples were collected from 15 peri-urban sites of three tehsils of district Vehari. Results showed that the mean concentration (mg/L) of Cd (0.02), Mn (0.25) and Fe (1.57) in wastewater samples was higher than their respective threshold values. Similarly, Cd, Mn and Fe concentration in soil was beyond the permissible limits of agricultural soil receiving wastewater irrigation. However, plants showed high accumulation of Pb, Cr and Fe than their respective limits depending on the vegetable/crop species. The health risk parameters showed that Pb and Cd are the major toxic chemical substances to human health, and the daily intake of crop plants can pose a potential health threat due to wastewater-irrigated crop consumption. Results highlighted the necessity of wastewater pretreatment to avoid the soil and vegetable contamination by wastewater irrigation and to reduce the associated health risks.

A Review of Environmental Contamination and Health Risk Assessment of Wastewater Use for Crop Irrigation with a Focus on Low and High-Income Countries.

Population densities and freshwater resources are not evenly distributed worldwide. This has forced farmers to use wastewater for the irrigation of food crops. This practice presents both positive and negative effects with respect to agricultural use, as well as in the context of environmental contamination and toxicology. Although wastewater is an important source of essential nutrients for plants, many environmental, sanitary, and health risks are also associated with the use of wastewater for crop irrigation due to the presence of toxic contaminants and microbes. This review highlights the harmful and beneficial impacts of wastewater irrigation on the physical, biological, and chemical properties of soil (pH, cations and anions, organic matter, microbial activity). We delineate the potentially toxic element (PTEs) build up in the soil and, as such, their transfer into plants and humans. The possible human health risks associated with the use of untreated wastewater for crop irrigation are also predicted and discussed. We compare the current condition of wastewater reuse in agriculture and the associated environmental and health issues between developing and developed countries. In addition, some integrated sustainable solutions and future perspectives are also proposed, keeping in view the regional and global context, as well as the grounded reality of wastewater use for crop production, sanitary and planning issues, remedial techniques, awareness among civil society, and the role of the government and the relevant stakeholders.