Abstract
Residents of Nepal's Kathmandu Valley draw drinking water from tube wells, dug wells, and stone spouts, all of which have been reported to have serious water quality issues. In this study, we analyzed drinking water samples from 35 tube wells, dug wells, stone spouts, and municipal tap water for bacterial and chemical contaminants, including total and fecal coliform, aluminum, arsenic, barium, beryllium, boron, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. We also asked a sampling of households who used these specific water sources to rate the taste of their water, list any waterborne diseases they were aware of, and share basic health information about household members. This survey provided us with information from 146 households and 603 individuals. We found widespread bacterial contamination of water sources, with 94% of sources having detectable total or fecal coliform. Nepal Drinking Water Quality Standards and World Health Organization (WHO) Drinking-Water Guidelines or health-based values were exceeded for aluminum (max = 0.53 mg/L), arsenic (max = 0.071 mg/L), iron (max = 7.22 mg/L), and manganese (max = 3.229 mg/L). The distribution of water sources with high arsenic, iron, and manganese appeared to be associated with floodplain deposits. Mixed effects logistic regression models were used to examine the interactions between social factors and water contaminants and their effects on household members' health. Consumers of water sources with both high and low concentrations of manganese were less likely to have a positive attitude towards school than those whose water sources had moderate concentrations of manganese. Social factors, especially education, played a large role in predicting individual health outcomes. Household taste ratings of drinking water were not correlated with iron or manganese concentrations, suggesting that WHO's reliance on aesthetic criteria for these contaminants instead of formal drinking-water guidelines may not be sufficient to protect public health.
Highlights
Accessing safe water is extremely difficult for the 1.7 million people of the Kathmandu Valley [1]
Kathmandu is within a nappe along the Main Himalayan rust, which accommodates movement of the Indian Plate into the Asian Plate at a rate of 40–50 millimeters/year [59]. e Kathmandu Valley is an intermontane tectonic basin within the Lesser Himalayan Mountains; see Figure 1(a) [60]. e basin is filled with mostly Quaternaryaged sediments up to 500 m thick, which overlie Precambrian and Paleozoic metamorphic rocks; see Figure 1(a) [61, 62]. e Pleistocene sediments in the valley are derived from a paleo-lake, which once filled the basin [60]. e lithology of these fluviolacustrine sediments
The sampling team recorded the Global Positioning System (GPS) coordinates and interviewed the source owner, caretaker, or a regular user to determine the age of the source, depth, and how many households use the source. e water was pumped or allowed to flow at full force for 5 minutes, and samples were collected into two separate 250 milliliter sterilized glass sampling bottles, one for bacterial analyses and one for chemical analyses. e water samples were not filtered, because this was an exposure assessment of drinking water; our objective was to measure the concentrations of total chemicals, not just dissolved chemicals. e pH of the flowing water was tested with a pH meter (Milwaukee Instruments Martini pH55, Rocky Mount, NC, USA)
Summary
Accessing safe water is extremely difficult for the 1.7 million people of the Kathmandu Valley [1]. Water from these sources is frequently contaminated with bacteria, nitrate (NO3−), and metals at unsafe levels. “Urgent need to reevaluate the latest World Health Organization guidelines for toxic inorganic substances in drinking water,” Environmental Health, vol 14, no. “Water quality, sanitation, and hygiene conditions in schools and households in Dolakha and Ramechhap Districts, Nepal: results from a cross-sectional survey,” International Journal of Environmental Research and Public Health, vol 14, no. “Perception of drinking water safety and factors influencing acceptance and sustainability of a water quality intervention in rural southern India,” BMC Public Health, vol 15, no. “Hair manganese and hyperactive behaviors: pilot study of school-age children exposed through tap water,” Environmental Health Perspectives, vol 115, no. “Hair manganese and hyperactive behaviors: pilot study of school-age children exposed through tap water,” Environmental Health Perspectives, vol 115, no. 1, pp. 122–127, 2007
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