Pesticide and Pathogen Contamination of Vegetables in Ghana’s Urban Markets

Abstract

The objective of the study was to determine and compare the current level of exposure of the Ghanaian urban population to hazardous pesticide and fecal coliform contamination through the consumption of fresh vegetables produced in intensive urban and periurban smallholder agriculture with informal wastewater irrigation. A total of 180 vegetable samples (lettuce, cabbage, and spring onion) were randomly collected under normal purchase conditions from 9 major markets and 12 specialized selling points in 3 major Ghanaian cities: Accra, Kumasi and Tamale. The samples were analyzed for pesticide residue on lettuce leaves, total and fecal coliforms, and helminth egg counts on all three vegetables. Chlopyrifos (Dursban) was detected on 78% of the lettuce, lindane (Gamalin 20) on 31%, endosulfan (Thiodan) on 36%, lambda-cyhalothrin (Karate) on 11%, and dichloro-diphenyl-trichloroethane on 33%. Most of the residues recorded exceeded the maximum residue limit for consumption. Vegetables from all 3 cities were fecally contaminated and carried fecal coliform populations with geometric mean values ranging from 4.0 x 10(3) to 9.3 x 10(8) g(-1) wet weight and exceeded recommended standards. Lettuce, cabbage, and spring onion also carried an average of 1.1, 0.4, and 2.7 helminth eggs g(-1), respectively. The eggs were identified as those of Ascaris lumbricoides, Ancylostoma duodenale, Schistosoma heamatobium, and Trichuris trichiura. Because many vegetables are consumed fresh or only slightly cooked, the study shows that intensive vegetable production, common in Ghana and its neighboring countries, threatens public health from the microbiologic and pesticide dimensions. Standard recommendations to address this situation (better legislations, law enforcement, or integrated pest management) often do not match the capabilities of farmers and authorities. The most appropriate entry point for risk decrease that also addresses postharvest contamination is washing vegetables before food preparation at the household or "chop" bar (street restaurant).

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

“…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.…”

“…In Accra, the capital of Ghana with a population of 2.7 million including its surrounding districts which are growing at 6 -9% per annum (Ghana Statistical Service 2002), the use of domestic wastewater for vegetable irrigation has been practiced for more than five decades due to limited access to potable water and freshwater resources (Anyane 1963;Asomani-Boateng 2002;Amoah et al 2006;IWMI 2006;Obuobie et al 2006). The practice provides a livelihood source to a number of poor urban households and contributes to the urban food basket (Keraita & Drechsel 2004;IWMI 2006).…”

Pesticide residues in fish from the Densu River Basin in Ghana

“…Causes of breast cancer, reduced sperm count, male sterility and death are well documented as a result of pesticide ingestion (Carvalho, 2006). Studies in Ghana indicated the presence of pesticide residues in vegetables, fruits and fish, at locations known for pesticide usage (Ntow, 2005;Amoah et al, 2006;Mensah et al, 2004;Aboagye, 2002). Growth in agrobased industries, increase in agriculture activities, improper storage and lack of sound disposal facilities have caused contamination of soil and water bodies resulting in a rapid increase in the number of pesticides into the Aquatic ecosystem (FAO/WHO, 2007).…”

Agrifood systems and the microbial safety of fresh produce: Trade-offs in the wake of increased sustainability

“…Fresh produce grown in such ways are often contaminated [4] with e.g. helminthes eggs (Amoah et al, 2006;Keraita et al, 2008a), as well as soil, as a consequence of repeated application of polluted water (Keraita et al, 2007a). Several constraints hamper strategies to reduce microbial risk.…”