Socio-economic background of wastewater irrigation and bioaccumulation of heavy metals in crops and vegetables

• Most of the farmers, in peri-urban area of study, preferred to use wastewater for lowering the cost of producing crops and vegetables.
• Poverty and scarcity of canal water might be the main factors, forcing farmers to adopt the unhealthy practice of waste water irrigation.
• Prolonged practices of wastewater irrigation has contaminated the soil and water sources with heavy metals.
• The Cr, Mn, Pb and Zn were assimilated in wastewater irrigated crops and vegetables at a concentration which, is unhealthy for human consumption.

Water scarcity is one of the main constraints for agriculture sector in many countries. It pushes the farmers to use wastewater for irrigation as an available alternate, especially in peri-urban areas of developing countries. One of the drawbacks of using wastewater for irrigation is heavy metal pollution in the soil and water along with the toxic elements which enter into the food chain. This study aims at to obtain information about the socio-economic reasons for using wastewater from the farmers’ perspective and analyze the accumulation of heavy metals in wastewater, canal water, underground water, soil and crops, irrigated with wastewater. Two contrasting views were observed among the farmers about wastewater irrigation. Over 90% preferred to use wastewater due to its low cost and rich source of nutrients. Although, farmers know that wastewater irrigation have serious negative effects on human health and the quality of the ground water, they prefer to use it for lowering the cost of production and overcome the scarcity of canal water. The findings of this study showed that, ground water and canal water have more accumulation of Cr, Mn, Pb and Zn than the recommended safe limits. None of the water samples collected from different sources was found to be safe for irrigation due to heavy metal contamination. Wastewater irrigated crops and vegetables were also analyzed to determine the bioaccumulation of heavy metals. Concentrations of Cr, Mn, Pb and Zn were observed more than safe limits in all the analyzed vegetables (spinach, cabbage, cauliflower, mustard leaves and round gourd) and crops (berseem, sorghum, maize, rice, wheat, lucerne, sugarcane). This study showed that poor economic conditions force the farmers to not only sacrifice their own health but also the health of consumers of these crops and vegetables by using wastewater for irrigation.