Microbial contamination along the main open wastewater and storm water channel of Hanoi, Vietnam, and potential health risks for urban farmers.
The use of wastewater in agriculture and aquaculture has a long tradition throughout Asia. For example, in Hanoi, it creates important livelihood opportunities for >500,000 farmers in peri-urban communities. Discharge of domestic effluents pollute the water streams with potential pathogenic organisms posing a public health threat to farmers and consumers of wastewater-fed foodstuff. We determined the effectiveness of Hanoi's wastewater conveyance system, placing particular emphasis on the quality of wastewater used in agriculture and aquaculture. Between April and June 2014, a total of 216 water samples were obtained from 24 sampling points and the concentrations of total coliforms (TC), Escherichia coli, Salmonella spp. and helminth eggs determined. Despite applied wastewater treatment, agricultural field irrigation water was heavily contaminated with TC (1.3×10(7)colony forming unit (CFU)/100mL), E. coli (1.1×10(6)CFU/100mL) and Salmonella spp. (108 most probable number (MPN)/100mL). These values are 110-fold above Vietnamese discharge limits for restricted agriculture and 260-fold above the World Health Organization (WHO)'s tolerable safety limits for unrestricted agriculture. Mean helminth egg concentrations were below WHO tolerable levels in all study systems (<1egg/L). Hence, elevated levels of bacterial contamination, but not helminth infections, pose a major health risk for farmers and consumers of wastewater fed-products. We propose a set of control measures that might protect the health of exposed population groups without compromising current urban farming activities. This study presents an important example for sanitation safety planning in a rapidly expanding Asian city and can guide public and private entities working towards Sustainable Development Goal target 6.3, that is to improve water quality by reducing pollution, halving the proportion of untreated wastewater and increasing recycling and safe reuse globally.
Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland. Electronic address: samuel.fuhrimann@unibas.ch.
Samuel
S
Fuhrimann
Center for Public Health and Ecosystem Research, Hanoi School of Public Health, Hanoi, Vietnam.
Phuc
P
Pham-Duc
Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
Guéladio
G
Cissé
Department of Microbiology, National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
Nguyen Thuy
NT
Tram
Department of Microbiology, National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
Hoang
H
Thu Ha
Department of Parasitology, National Institute of Malaria, Parasitology, and Entomology, Hanoi, Vietnam.
Do Trung
DT
Dung
Department of Animal Hygiene, National Institute for Veterinary Research, Hanoi, Vietnam.
Pham
P
Ngoc
Center for Public Health and Ecosystem Research, Hanoi School of Public Health, Hanoi, Vietnam; International Livestock Research Institute, Hanoi, Vietnam.
Hung
H
Nguyen-Viet
Department of Microbiology, National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
Tuan
T
Anh Vuong
Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
Jürg
J
Utzinger
Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
Christian
C
Schindler
Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
Mirko S
MS
Winkler
D000383:Agriculture; D000818:Animals; D017756:Aquaculture; D002947:Cities; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D004926:Escherichia coli / Q000302:isolation & purification; D000067565:Farmers; D006376:Helminths / Q000302:isolation & purification; D006801:Humans; D010270:Parasite Egg Count; D018570:Risk Assessment; D012475:Salmonella / Q000302:isolation & purification; D014744:Vietnam; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000382:microbiology* / Q000469:parasitology
D062065:Wastewater
Escherichia coli; Helminths; Salmonella spp.; Sanitation safety planning; Sustainable Development Goal; Wastewater use; Water quality