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).

Accessibility to abundant sources of high-quality water is integral to the production of safe and wholesome fresh produce. However, access to safe water is becoming increasingly difficult in many parts of the world, and this can lead to the production of fresh produce contaminated with pathogenic microorganisms, resulting in increased risk of human disease. Water, an important raw material in the fresh produce chain, is used in considerable amounts in many operations, including irrigation and application of pesticides and fertilizers, but also as a transport medium and for cooling and washing in postharvest practices. In several reported outbreaks related to uncooked fruit and vegetable products, water has been identified as a likely source of the outbreak. The present study, initiated by the ILSI Europe Emerging Microbiological Issues Task Force in collaboration with 8 other ILSI branches and support of WHO/FAO, was undertaken to review the status of, and provide suggestions for, consideration by different stakeholders on water and sanitation and its impact on food safety and public health. A limited number of guidelines and regulations on water quality for agricultural production are available, and many of them are still heavily based on microbial standards and (debated) parameters such as fecal coliforms. Data gaps have been identified with regard to baseline studies of microbial pathogens in water sources in many regions, the need for agreement on methods and microbial parameters to be used in assessing water quality, the fate of pathogens in water, and their transfer and persistence on irrigated/processed produce.

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.

Summaryobjective To analyse and improve the effectiveness of common indigenous washing methods for the reduction of faecal coliform (FC) populations on the surface of wastewater-irrigated vegetables and to determine simple factors affecting their efficacy.methods Questionnaire interviews were used to gather information on common methods used for washing vegetables in seven West African countries. The efficacy of the most common decontamination methods was measured in terms of log reductions in FC populations on homogenised contaminated lettuce, cabbage and spring onion samples.results The large majority of urban households and restaurants in the subregion are aware of vegetable-related health risks and wash vegetables before consumption. Methods used vary widely within and between Ghana and neighbouring francophone West African countries. However, several of the most common methods do not reduce the contamination to any desirable level. Significantly, different log reductions are achieved depending on the washing method, contact time and water temperature. Tests to improve the apparent ineffective methods were especially promising in view of the relatively expensive vinegar. However, up to 3 log units reduction is also possible at a much lower price with 'Eau de Javel' (household bleach), which is commonly used in francophone West Africa.conclusion Washing vegetables before consumption is an important component of a multiple barrier approach for health risk reduction. The high risk perception among consumers demands that more information be made available on the appropriate use of these washing methods. Any washing method will need complementary efforts to reduce contamination before the vegetables enter the kitchen, such as safer irrigation practices.

Microbiological water and crop contamination was monitored on urban vegetable farms in Ghana. Faecal coliform and helminth egg contamination levels of irrigation water from drains, streams and shallow wells significantly exceeded WHO recommendations for unrestricted irrigation. High faecal coliform levels exceeding common guidelines for food quality were also recorded on lettuce irrespective of the irrigation water source, with significantly lower coliform concentrations on lettuce irrigated with piped water than with shallow well or stream water. Higher crop contamination levels were observed in the rainy season in spite of lower irrigation frequencies, compared to the dry season. The main species of helminth eggs isolated in water and on lettuce were Ascaris lumbrecoides, Hymenolepis diminuta, Fasciola hepatica and Strogyloides larvae. Results from field trials showed that apart from wastewater, already contaminated soil as well as poultry manure also contribute to crop contamination, but contributions from these sources could be only partially quantified. The need to reduce the potential health risks resulting from faecal coliform and helminth contamination of urban and peri-urban vegetables thus needs a more holistic approach than a simple focus on irrigation water quality. Copyright # 2005 John Wiley & Sons, Ltd.key words: wastewater; lettuce; coliforms; helminthes; urban agriculture; Ghana RÉ SUMÉ La contamination de l'eau microbiologique et de la récolte a fait l'objet d'un contrôle dans les fermes de culture de légumes au Ghana. Les niveaux de contamination des coliformes fécaux et des oeufs d'helminthe irrigués par l'eau provenant des canalisations, courants, et dans les bas-fonds ont dépassé de façon plus que significative les recommandations de l'OMS concernant l'irrigation illimitée. Des niveaux de coliformes fécaux élevés dépassant les directives communes relatives à la qualité de la nourriture ont également été enregistrés pour la laitue sans tenir compte de l'irrigation des sources d'eau, avec des concentrations de coliformes excessivement basses sur la laitue irriguée à l'aide d'eau potable, que sur celle irriguée avec de l'eau de puits, ou de l'eau des ruisseaux. Des niveaux plus élevés de contamination des récoltes ont été remarqués durant la saison des pluies en dépit des irrigations plus espacées, en comparison avec la saison sèche. Les espèces principales des oeufs d'helminthe isolées dans l'eau et sur la laitue étaient des larves de Ascaris lumbrecoides, Hymenolepis diminuta, Fasciola hepatica et de Strogyloides. Les résultats des essais dans les champs ont montré que sauf les eaux résiduaires, un sol déjà contaminé ainsi que le fumier de volaille contribuent à la contamination des cultures, bien que la contribution de ces sources pourrait être uniquement quantifiée de manière partielle. La nécessité de réduire les risques sanitaires potentiels provenant de la contamination des coliformes fécaux et des oeufs d'helminthe qui affecte les légumes poussant dans des zones périurbaines a l...