Implications of irrigation water quality on shallow groundwater in the Nile Delta of Egypt: A human health risk prospective

Groundwater is the main source for drinking in Egypt, especially in rural communities; however, water quality of shallow aquifers is more susceptible to human activities. The current work aimed at evaluating groundwater quality for drinking and associated health risks in an area of the Nile Delta (30 degrees 14 '' 47 '' to 30 degrees 17 ' 51 '' N and 31 degrees 17 ' 38 '' to 31 degrees 20 ' 12 '' E) in response to irrigation water quality. Thirty groundwater samples were collected from three irrigated sites (ten samples from each site); the Nile freshwater (NFW), the agricultural drainage water (ADW), and mixed wastewater (MWW) irrigated sites. Overall, ranges of pH, Ca2+, Mg2+, F-, NO3-, Cu, Mn, Ni, and Zn were within the permissible levels according to Egypt and WHO drinking water standards, while the count of total and fecal coliform bacteria exceeded safety limits. The water quality index indicated that samples from the NFW-, ADW- and MWW-irrigated sites had moderate to good, low, and low to moderate qualities, respectively. On average, the hazard index (HI) indicated no potential non-cancer risk for adults (HI < 1.0) in the three sampling sites, while children in the MWW-irrigated sites would suffer adverse health risks (HI > 1.0). The mean total cancer risk (TCR) was in the acceptable range (1.0 x 10(-6) to 1.0 x 10(-4)) for adults in two sites (the NFW- and ADW-irrigated sites), while adults in the MWW-irrigated sites and children in all sampling sites would suffer cancer risks over the lifetime (TCR > 1.0 x 10(-4)). The potential cancer risk would be mainly due to Ni exposure via the oral route, and thus further management studies should be considered to mitigate the adverse effects. This study would provide a useful database for decision and policymakers for protecting shallow groundwater quality and reduce potential human health risks. (C) 2021 Elsevier B.V. All rights reserved.