Wastewater use in urban agriculture: an exposure and risk assessment in Accra, Ghana

Abstract

Wastewater use in urban agriculture is common as a result of rapid urbanisation and increasingcompetition for water. This study sought to assess critical exposures associated with the transmission of faecal pathogens among farmers and consumers of wastewater irrigated produce andto assess the adoption of the multiple-barrier approach advocated by the WHO guidelines tominimise health risks. From September 2012 to August 2013, 323 soil and irrigation water samples,and 501 raw produce and ready-to-eat salad samples were collected from fields, markets,and kitchens in Accra, Ghana. All samples were analysed for E. coli using standard procedures.In addition, 693 participants including farmers, vendors, and consumers were interviewed andobserved. The results showed that irrigation water was significantly more contaminated thanfarm soil, though exposure to soil was found to pose the key risk to farmers due to hand-to mouth  events (10 events/day). Over 80% of the produce samples were found contaminated with E. coli, with street food salad found to be the most contaminated (4.23 Log E. coli/g). Risk factors identified for produce contamination included farm soil, wastewater use, and poor food and environmental hygiene. Awareness of the source of irrigation water was low, but despite the high awareness of health risk, consumers did not prioritize health indicators when buying produce.The study recommends the promotion of interventions that would result in more direct benefits to producers and vendors, together with hygiene education/inspection, hygiene certification, andenforcement of food safety byelaws in order to protect health.

Keywords: Ghana, wastewater irrigation, produce, risk perceptions, multiple-barrier approach