Water quality indices appraisal and health risk assessment of nitrate, mercury and lead in water distribution network: A case study of Robat Karim in Tehran, Iran

Abstract

Groundwater is a basic source of drinking water supply for urban and rural areas. This is especially the case for communities located in arid and semi‐arid regions that rely on groundwater for drinking purposes. The present study set out to assess the potential health impacts of water impurities and to investigate the qualitative status of drinking water in Robat Karim rural areas, located in southwest Tehran, Iran. A total of 66 samples were collected from the water distribution network of 11 villages (33 sampling points, on two occasions) during September 2020 and were tested in terms of the most common quality parameters such as pH, mercury (Hg), lead (Pb), copper (Cu), zinc (Zn), chloride (Cl–), chlorate (ClO3–), nitrite (NO2–), nitrate (NO3–), and flouride (F–). Multiple methods and indexes including water quality index (WQI), hazard quotient (HQ), and hazard index (HI), were worked out to assess the quality of water and health risk assessment of NO3– Pb2+ and Hg2+. The results revealed that 33% and 90% of sampling sites have significantly high nitrate and total hardness (TH) concentrations, exceeding the maximum permissible limits set by World Health Organization (WHO; 50 and 200 mg/L, respectively). Furthermore, five sampling points exhibited poor WQIs mainly related to NO3– and TH. HQ values higher than 1 for nitrate were noticed in most sampling locations. Except for one sampling point, the HQ obtained for Pb2+ and Hg2+ were below 1 indicating no obvious health hazard. This study represents that children and infants are at higher risk of chronic toxicity by excess NO3– intake. The health hazard that is yet imposed on the community by NO3– necessitates regular monitoring of drinking water, the use of advanced technologies to purify water or otherwise alternative resources should be proposed.

Human health risk of nitrate in groundwater of Tehran–Karaj plain, Iran

“…In addition, the unbalanced use of N-compounds’ fertilizers (annually around 200 kg/ha) for nourishing the green spaces and parks across the city introduces a large nutrient load to the aquifer 33 , 47 , 61 . The southeast part of the plain has mainly been covered by farmlands, which is an agricultural hub to meet the food demands for Tehran and Alborz provinces and nearby cities 45 . These farmlands are supported by unbalanced use of fertilizers 15 , 40 , which mainly include N-compounds (e.g., urea, ammonium sulfate, ammonium nitrate, and calcium nitrate), P-compounds (e.g., mono-ammonium phosphate and mono-potassium phosphate), K-compounds (e.g., potassium nitrate, potassium chloride, and potassium sulfate), and animal waste-based fertilizers such as cattle and poultry manures.…”

“…Kalteh et al 44 assessed non-carcinogenic health risk of nitrate in 148 tap water samples taken from six districts of Tehran’s city in 2022. In another conducted study, Badihi et al 45 used 66 drinking water samples taken from southwest region of Tehran in 2020 to assess their non-carcinogenic health risks of nitrate for end-users. However, a few studies have investigated the human health risk of nitrate in the groundwater wells using sporadic data that covered only some parts of the aquifer in a short window 15 , 44 , 45 .…”

“…In another conducted study, Badihi et al 45 used 66 drinking water samples taken from southwest region of Tehran in 2020 to assess their non-carcinogenic health risks of nitrate for end-users. However, a few studies have investigated the human health risk of nitrate in the groundwater wells using sporadic data that covered only some parts of the aquifer in a short window 15 , 44 , 45 . In addition, the plain has exposed to an elevated production of pollution loads due to expanded urbanization and industrial-agricultural development, which could further rich the aquifer with nitrate concentration during the study period.…”

Potential health hazard of drinking water in restaurants and tea stalls

“…The hardness of DW is due to the presence of Ca +2 and Mg +2 ions originating from the soil, rock, sediment, and minerals. The presence of a small amount of hardness in DW is beneficial for the human cardiovascular system, but excess is detrimental to health (Badihi et al, 2022). The iron (total) concentration in DW is 0 to 1.19 mg/L with an average of 0.118 mg/L, which is much less than the WHO guideline (0.3 mg/L).…”