Accumulation of phytotoxic metals and metalloids in vegetable continuum subjected to different irrigation streams: a threat towards nutritional security

Abstract

The urban agro-ecosystem in developing countries plays a major role in uplifting the socioeconomic status of their inhabitants by confronting the challenges of improving food security and eradicating hunger. Food security and safety has become a serious global concern owing to accumulation of phytotoxic metals and metalloids in different food commodities subjected to different contaminated irrigation sources. The current study was undertaken to assess the concentrations of heavy metals and metalloid in ridge gourd (Luffa cylindrica L.), its planting soil medium and irrigation water sources used for crop production to determine the health risk. The results showed that the mean concentrations of different metals and metalloids in ground water samples i.e. Ni (0.14 mg L-1), Fe (1.29 mg L-1), Cu (0.10 mg L-1), Pb (0.55 mg L-1), As (0.10 mg L-1), Cr (2.38 mg L-1) and Cd (0.05 mg L-1) were over the permissible limits. Soil samples irrigated with ground water showed that concentrations of Cd (23.67 mg kg-1), Cr (26.66 mg kg-1) and As (45.97 mg kg-1) were above the permissible limits. Similarly, vegetable samples irrigated with ground water had a higher level of Cd (0.33 mg kg-1) than their prescribed safe limits. The bio-concentration factor ranged from 0.00 to 8.21 for all irrigation sources. The target hazard quotients (THQ) for Zn, Fe, and Cr were higher than the threshold value when ridge gourd was consumed, indicating a health concern. Similarly, hazard index values were 5.05, 28, 27, and 1.01, from groundwater, canal water, and sewage water, respectively. Target Cancer Risk (TCR) exposed Ni, Cr, Cd and As in canal water were sources of high cancer risk and Pb showed moderate cancer risk for the local community. These findings suggest that human intake of ridge gourd vegetable from the studied area may pose health hazards. Hence, frequent monitoring of different irrigation streams used in urban and semi-urban agriculture is strongly recommended to manage higher concentrations of phytotoxic metals and metalloids in crop produce and their associated health risks for humans.