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%, lambdacyhalothrin (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 ·
103 to 9.3 · 108 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)
