A Farm to Fork Risk Assessment for the Use of Wastewater in Agriculture in Accra, Ghana.

• Type of Material: Article
• Authors: Prince Antwi-Agyei, London School of Hygiene and Tropical Medicine; Sandy Cairncross, London School of Hygiene and Tropical Medicine; Anne Peasey, University College of London; Vivien Price, London School of Hygiene and Tropical Medicine; Jane Bruce, London School of Hygiene and Tropical Medicine; Kelly Baker, Emory University; Christine Moe, Emory University; Joseph Ampofo, Council for Scientific and Industrial Research (CSIR); George Armah, University of Ghana; Jeroen Ensink, London School of Hygiene and Tropical Medicine
• Language: English
• Date: 2015-11-10
• Publisher: Public Library of Science
• Publication Version: Final Published Version
• Copyright Statement: © 2015 Antwi-Agyei et al.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pone.0142346
• Title of Journal or Parent Work: PLoS ONE
• ISSN: 1932-6203
• Volume: 10
• Issue: 11
• Start Page: e0142346
• End Page: e0142346
• Grant/Funding Information: The study was funded by the Sanitation and Hygiene Applied Research for Equity (SHARE) Research consortium (www.shareresearch.org) through a UK aid from the Department for International Development (DFID). PAA received this funding for this study as part of his PhD scholarship.
• Keywords: Lettuce; Agricultural irrigation; Vendors; Hygiene; Farms; Food consumption; Norovirus; Escherichia coli infections
• Research Categories: Agriculture, Food Science and Technology; Health Sciences, Public Health

Abstract

The need to minimise consumer risk, especially for food that can be consumed uncooked, is a continuing public health concern, particularly in places where safe sanitation and hygienic practices are absent. The use of wastewater in agriculture has been associated with disease risks, though its relative significance in disease transmission remains unclear. This study aimed at identifying key risk factors for produce contamination at different entry points of the food chain. Over 500 produce and ready-to-eat salad samples were collected from fields, markets, and kitchens during the dry and wet seasons in Accra, Ghana, and over 300 soil and irrigation water samples were collected. All samples were analysed for E. coli, human adenovirus and norovirus using standard microbiological procedures, and real time RT-PCR. Finally, critical exposures associated with microbial quality of produce were assessed through observations and interviews. The study found that over 80% of produce samples were contaminated with E. coli, with median concentrations ranging from 0.64 to 3.84 Log E. coli/g produce. Prepared salad from street food vendors was found to be the most contaminated (4.23 Log E. coli/g), and that consumption of salad exceeded acceptable health limits. Key risk factors identified for produce contamination were irrigation water and soil at the farm level. Storage duration and temperature of produce had a significant influence on the quality of produce sold at markets, while observations revealed that the washed water used to rinse produce before sale was dirty. The source of produce and operating with a hygiene permit were found to influence salad microbial quality at kitchens. This study argues for a need to manage produce risk factors at all domains along the food chain, though it would be more effective to prioritise at markets and kitchens due to cost, ease of implementation and public health significance.