Irrigated urban vegetable production in Ghana: microbiological contamination in farms and markets and associated consumer risk groups

Abstract

Ghana is a typical low-income sub-Saharan African country facing significant sanitation challenges. In Ghana, fresh salads are not part of the normal diet, but have become a common supplement to urban fast food served in streets, canteens and restaurants. In Accra, about 200 000 people consume from such supplements every day. The figure also describes the size of the risk group from contamination, which comprises all income classes including the poor and children. The purpose of this study was to investigate widespread water pollution in urban and peri-urban areas, where 95% of the lettuce consumed in the city is produced. Over 12 months (April 2004-June 2005, lettuce samples from the same production sites in two cities were followed and analyzed along the "farm to fork" pathway for total and faecal coliform (FC) and helminth egg numbers. Questionnaire surveys were conducted among producers, sellers and consumers to quantify lettuce flows to the final risk group. The study identified the farm as the main point of lettuce contamination. Besides the irrigation water, contamination was also attributed to manure application and already contaminated soil. Despite poor sanitary conditions in markets, post-harvest handling and marketing did not further increase the farm-gate contamination levels. To reduce the health risk associated with the consumption of contaminated lettuce; safer farming and irrigation practices are required while the remaining risk could best be addressed where lettuce is prepared for consumption.

Quantification of the health risk associated with wastewater reuse in Accra, Ghana: a contribution toward local guidelines

“…Details of the methods used for the microbial enumeration as well as issues regarding quality assurance have been comprehensively presented elsewhere (Amoah et al 2005(Amoah et al , 2007a. In addition a comprehensive literature review of international peer reviewed journals was undertaken to provide inputs for hazard identification, doseresponse assessment, exposure assessment and risk characterisation.…”

“…Institute (IWMI) office in Accra with several national and international partners has undertaken a number of studies under its projects CPWF38 and 51, to ascertain and reduce the potential health hazards associated with the practice (Keraita et al 2007;Keraita & Drechsel 2004;Amoah et al 2006Amoah et al , 2007aObuobie et al 2006). This work is an extension of the IWMI studies and aims at quantifying the doi: 10.2166/wh.2008.118 health risks associated with the practice using the Quantitative Microbial Risk Assessment (QMRA) approach.…”

“…Microbial investigations undertaken so far on wastewater reuse in Accra have focused on the quantification of helminths eggs and faecal coliforms (FC) (Keraita & Drechsel 2004;Obuobie et al 2006;Amoah et al 2006Amoah et al , 2007a. For purposes of our assessment, we chose rotavirus and Ascaris lumbricoides as the model organisms.…”

Give peas a chance? Urban agriculture in developing countries. A review

“…The fecal contamination of these waters is of particular concern when used to irrigate vegetables consumed without cooking, such as exotic salad vegetables and lettuce (Amoah et al 2005;Amponsah Doku 2010). While farmers typically perceive risks to consumers as low (Keraita et al 2008a, b;Owusu et al 2012), evidence of unsafe levels of fecal contamination on produce has been documented (Amoah et al 2007).…”

Assessment of heavy metal contamination in soil due to leachate migration from an open dumping site

“…Most of the disposal sites are unfenced and open firing of municipal solid waste is very common. It putrefies easily under the hot tropical temperatures and generates considerable quantities of leachates and obnoxious odor (Everett 1992;Knoll 1983;Adhikari et al 2006;Amoah et al 2007). Under such circumstances, organic waste may also act as an important breeding site for disease causing vermin including flies, insects and rodents, which are vectors of diseases such as cholera, diarrhea, dysentery and typhoid fever (Fobil et al 2008;Everett 1992;Knoll 1983;Afrane et al 2004;Krajewski et al 2001;Musmeci and Gucci 1997).…”