Contributions to the Discussion

Contributions AUGUST 21 - 24, 2000

 

1. From: The moderators UPA-Health
Date: Monday August 21
Subject: Opening Questions, Preguntas de arranque, Questions de ouverture

Dear Participants in the discussion on UPA, Health and Environment,

We warmly welcome you to the next six weeks of discussion on these topics. We hope that you will be active participants in the workshop by sending in your contributions to the discussion. The purpose of this message is to present the opening questions for our first session of discussion.

As was explained in the conference announcement, we will have three rounds of discussions. For each of these, we have formulated some opening questions. We encourage you to put forward other questions and propositions that you would like to see discussed.

Please read the background paper as we hope it will elicit contributions.

In this first session (August 21 - September 1), we will focus on: Fact-finding and situation analysis. We invite your ideas about one or more of the following questions:

a.. What are the health risks associated with UPA that - in your experience - can cause negative impacts on the urban population?
Provide examples and references if they are available. Which population is most vulnerable to these risks (gender, age, main occupation, socio-economic status, etc.)?
b.. What positive impacts of UPA on health and environment do you observe?
Provide examples and references if they are available.
c.. Please summarise the local situation under which these health risks and / or benefits were encountered and the environmental conditions that in your opinion played an important role in creating these health risks and / or benefits.
d.. In your opinion, do the positive health impacts outweigh the negative impacts?
How can these impacts be measured and evaluated?
e.. Are the observed health risks primarily associated with urban poverty, or with urban environmental management problems or with agriculture as such? Please explain.

In the second session (September 4 - September 15), we will seek to assess Policy choices for UPA regarding health and environment issues.

In the final session (September 18 - September 29), we will turn to questions regarding Implementation of changes in UPA with regard to health and environment issues.

We look forward to an interesting and lively discussion with you. We encourage an informal and open atmosphere - as if we were chatting around the table at a live conference. All contributions are valuable and welcome. We don't need a learned thesis; the goal is to share ideas and experiences from all sources.

Thank you,

Henk de Zeeuw,
co-ordinator RUAF, ETC International

Karen Lock,
visiting research fellow, London School of Hygiene and Tropical Medicine

Chers Participants au groupe de discussion sur l'AUP, la Santé et l'Environnement Urbain

Nous vous invitons chaleureusement à participer aux six semaines de discussion à venir sur ces thèmes suivants. Nous espérons que vous participerez activement aux ateliers en nous envoyant vos contributions aux discussions. L'objectif de ce document est de présenter les questions qui ouvriront la première session de discussion.

Ainsi que nous l'avons expliqué dans l'annonce de la conférence, trois séries d'échanges de vues seront organisées. Nous avons formulé pour chacune d'entre elles un certain nombre de questions directrices. Vous êtes libres de nous soumettre d'autres questions et propositions qui selon vous méritent d?être abordées.

Veuillez vous reporter au document de référence, nous espérons qu'il suscitera vos réactions et vos contributions.

Au cours de la première session (21 août - 1er septembre ), nous aborderons le thème suivant : Etablissement des faits et analyse de la situation. Nous vous prions de bien vouloir examiner une ou plusieurs des questions suivantes :

a.. Quels sont, d'après votre expérience, les risques sanitaires liés à l'AUP qui comportent un impact négatif sur la population urbaine ?
Veuillez fournir des exemples et des références si vous en avez. Quelles sont les caractéristiques des populations les plus exposées à ces risques ? (sexe, âge, activité principale, statut socio-économique, etc.)
b.. Quels impacts positifs de l'AUP sur la santé et l'environnement avez-vous observés ?
Veuillez fournir des exemples et des références si vous en avez.
c.. Veuillez résumer les conditions locales dans lesquelles se sont présentés de tels risques sanitaires et / ou bienfaits, et les conditions environnementales qui selon vous ont fortement contribué à leur apparition.
d.. D'après vous, les répercussions sanitaires positives l'emportent-elles sur les répercussions négatives ?
Comment peut-on mesurer ou évaluer ces répercussions?
e.. Les risques sanitaires observés sont-ils surtout liés à la pauvreté urbaine, aux problèmes de gestion de l'environnement urbain, ou à l'agriculture en tant que telle ? Veuillez expliquer votre réponse.

Au cours de la deuxième session (4 septembre - 15 septembre ), nous examinerons les Choix de politiques liés aux aspects sanitaires et environnementaux de l'AUP.

Au cours de la dernière session (18 septembre - 29 septembre ), nous traiterons des questions sur le thème : Mise en oeuuvre des changements liés à l'AUP, la Santé et l'Environnement Urbain.

Nous espérons que les discussions seront intéressantes et animées. Nous encourageons une atmosphère ouverte et informelle - comme si nous étions vraiment tous réunis autour d'une table de conférence. Toutes les contributions sont dignes d?intérêt et les bienvenues. Nous ne voulons pas de thèses savantes ; l'objectif est d'échanger des idées et des expériences de toutes sortes.

Merci par avance.

Henk de Zeeuw,
coordinateur du Centre de Ressources sur l'Agriculture Urbaine et les Forêts (RUAF), ETC International, Pays Bas

Karen Locke,
attachée de recherche invitée de l'Ecole d'Hygiène et de Médecine Tropicale de Londres, Grande Bretagne

Estimados Participantes de la discusión sobre AUP y Salud y Medio-Ambiente.

Nosotros les damos la bienvenida cariñosamente a la discusión sobre estos temas para las próximas seis semanas. Esperamos su participación activa en el taller enviándonos sus contribuciones para la discusión. El propósito de este mensaje es presentar preguntas de apertura para nuestra primera sesión de discusión.

Como fue explicado en la presentación de la Conferencia, tendremos tres rondas de discusión. Para cada una de estas, hemos formulado algunas preguntas de apertura. Nosotros les invitamos a colocar otras preguntas y propuestas que a ustedes les gustaría sean discutidas.

Por favor lea el documento de antecedentes ya que esperamos que este generará contribuciones.

En esta primera sesión (agosto 21-septiembre 1) nos centraremos en hechos encontrados y análisis de situación. Invitamos a contribuir con sus ideas con una o más de las siguientes preguntas:

a.. ¿Cuáles son los riesgos de salud relacionados con la AUP que -en su experiencia- causan un impacto negativo en la población urbana?
Menciones ejemplos y referencias. Cuáles son las características de la población más afectada (sexo, edad, ocupación principal, situación socioeconómica, etc.)
b.. Presente una reseña de la situación local en la que estos riesgos se pueden encontrar y las condiciones ambientales que, en su opinión, jugaron un papel importante en la creación de estos riesgos de salud.
c.. ¿Cuáles son los impactos positivos de la AUP sobre salud y el medio-ambiente que usted haya observado?.
En su opinión, superan estos efectos positivos sobre la salud a los efectos negativos?
Cómo se podría monetorear y evaluar esto?
d.. ¿Cuál es la principal contribución a los riesgos de salud relacionada actualmente con la AUP?
En su opinión los riesgos de salud observados se relacionan principalmente con la pobreza urbana, problemas de administración del medio ambiente o con la propia actividad agrícola? Por qué?

En la segunda sesión (septiembre 4 - septiembre 15) buscaremos acceder a la selección de políticas para AUP relacionadas con la salud y temas medio-ambientales.

En la sesión final (septiembre 18-septiembre 29) nos volcaremos a preguntas relacionadas a la implementación de los cambios en AUP con relación a la salud y temas medio-ambientales.

Esperamos entonces una discusión interesante y dinámica con ustedes. Proponemos una atmósfera abierta e informal - como si nosotros estuviéramos conversando alrededor de una mesa en vivo. Todas las contribuciones son valoradas y bienvenidas. No necesitamos una tesis bien elaborado; el objetivo es compartir ideas y experiencias de todo tipo.

Gracias,

Henk de Zeeuw,
Coordinador de RUAF, ETC Internacional

Karen Lock,
Investigadora invitada, Escuela de Higiene y Medicina Tropical de Londres.

2. From: Jo Lines (LSHTM)
Date: August 22
Subject: Malaria

I wonder how many professionals involved in Urban Agriculture in Africa are aware that small agricultural plots are by far the most important source of malaria vectors in African towns and cities.

Not surprisingly, some crops are far more important than others: rice is the worst, followed by other wet crops such as sweet potato and yam, followed by other forms of ridge-cultivation including cassava. Maize and bananas, on the other hand, are completely innocent. This is because African malaria vectors prefer to breed in shallow, sunlit, and often temporary bodies of surface water on the ground. They are only exceptionally found in man-made containers or in polluted water.

It is worth noting that these priorities are completely at odds with the targets normally selected by community--based "environmental hygiene" campaigns. All over Africa, there is a widespread belief that clearing bush and long grass around houses helps to give some protection against mosquitoes. When this is put into practice, it often extends to the slashing of maize and banana crops. Another common priority in such campaigns is clearing of polluted stormwater drains. These are important sources of Culex mosquitoes, but are not important at all for malaria vector Anopheles. Similarly, small containers such as broken bottles, cans and coconut shells are often targeted in local clean-up campaigns. Anopheles malaria vectors do not breed in such places. Small containers are the main breeding sites for Aedes mosquitoes, and are therefore of publlic health importance in the limited Yellow Fever areas of West Africa, but not elsewhere in the continent.

In many African communities, people are often exhorted by community leaders and by health education messages to join in with community sanitation campaigns for the sake of malaria control. These activities may well have other more general enviromental benefits. But they are hardly ever directed at the real source of the malaria problem, and are therefore normally useless for the stated purpose of malaria control.

It is also worth noting that in social terms, malaria vectors grown in urban agricultural plots are comparable to many other forms of man-made enviromental pollution. They represent an unintended and harmful side-effect of an economic activity. And as with other forms of pollution, the problem is that the costs and benefits affect different groups of people. The economic benefits are enjoyed exclusively by the cultivators and / or owners of the plot, while the health costs are shared by the entire surrounding community. There is therefore a genuine conlfict of interest between the cultivators and other people in the area.

Jo Lines,
LSHTM (jo.lines@lshtm.ac.uk)

3. From: Pay Dreschel
Date: August 22
Subject: Food contamination by use of uncomposted poultrymanure

NB The following contribution is a part of an article prepared for the next issue of Urban Agriculture Magazine, to be published in September. The authors suggested us to distribute selected parts of their article as a contribution to this discussion on UPA and Health. I made the selection. Henk de Zeeuw, moderator UPA-Health

Kumasi, the capital of the Ashanti Region in Ghana, has a population of approximately one million. Livestock production is a vital part of urban agriculture in Kumasi, where many farmers benefit from large amounts of cheap manure. Estimations including peri-urban Kumasi indicate an annual (dry matter) production of about 34,000 t poultry manure (Kindness 1999). Many poultry farmers consider the litter as waste and give it for free to crop or fish farmers and part of the litter is dumped on roadsides and burnt.

Vegetable and fish farmers in and around Kumasi benefit from the large generation of especially poultry manure which offers them access to a high quality fertiliser for little money. The potential of this resource is increasingly realised. However, poultry manure has not only advantages but is also a carrier of pathogens and appropriate handling of the manure and crops is necessary to reduce any potential health hazard. Adequate composting would reduce the risks, thus well-heaped litter is recommended (Amoah, 2000).

In practice, however, this is seldom realised. With increasing demand for this resource, vegetable farmers are competing for poultry manure. They started to offer poultry farmers fresh bedding material (usually wood shavings) in exchange for manure enriched litter. Thus, the large majority of poultry farmers who give the litter to crop farmers do not store it before it leaves the farm. Also nearly no crop farmers who asked for litter enquired about its maturity. After collections, about 60% apply the poultry litter directly without further composting while 40% heap the litter for some weeks or more depending on the date they need it on their fields.

The application of poultry litter without adequate composting constitutes a potential source of food contamination. This concerns especially leafy vegetables as every second farmer broadcasts the litter over the already established crops. During irrigation, the litter is largely washed down, however, farm gate samples of lettuce, cabbage and onions from poultry manure treated fields still contained high levels of total and faecal coliforms.

With regard to the accompanying health hazard through the use of insufficiently composted manure, corresponding extension guidelines for vegetable farmers are needed. However, it can be doubted that the farmers have currently much possibilities to change their way of production. Therefore, interventions to prevent the spread of gastro-intestinal infection should focus on the consumer household. Still a certain part of the population is not washing vegetables regularly and / or has no access to in-house piped water. In a further step, farmers' access to clean water has to be assured with special attention to farmers' own contribution to water contamination.

Pay Drechsel*, Robert C. Abaidoo+, Philip Amoah*,+ and Olufunke O. Cofie* *IBSRAM Project on Urban Waste Recycling in Ghana, IBSRAM Office, KNUST, Kumasi, Ghana + Department of Biological Sciences, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana

References

Amoah, P. 2000. Identification of suitability indices of poultry litter for cowpea and maize production. M.Sc. thesis, Faculty of Science, Kwame Nkrumah university of science and technology (KNUST), Kumasi.

Kindness, H. 1999. Supply and demand for soil ameliorants in peri-urban Kumasi. Kumasi Natural Resources Management Project, KNUST / NRI / DFID

Mensah, E., Amoah, P., Drechsel, P. and R.C. Abiadoo. 2000. Environmental concerns of urban and peri-urban agriculture: Case studies from Accra and Kumasi. In: Drechsel, P. and D. Kunze (Eds.) Waste Composting for Urban and Peri-urban Agriculture - Closing the rural-urban nutrient cycle in sub-Saharan Africa. CABI-IBSRAM-FAO (in press)

4. From: Isabel Madaleno (Tropical Institute Lisboa)
Date: August 23
Subject: Paper 'City Food and health in Brazil'
This paper was added to the Information Market (www.ruaf.org) in the section: Papers on UPA and Health

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From: Steve Esrey (ICG)
Date: August 23
Subject: malaria webpage MARA

Steve Esrey (ICG) forwarded the information that recently the West and Central Africa MARA (Mapping Malaria Risk in Africa) centers and WARDA (West Africa Rice Development Association) are developing predictive models and a regional, ecologically stratified, malaria endemicity map for West and Central Africa. WARDA is also maintaining a webpage with information on the relationship between irrigation / wetland rice farming and malaria and schistosomiasis risk in West Africa. More information and the web address will be put on the Information market.

5. From: Leo van den Berg
Date: August 24
Subject: some myths; monitoring and certification

Dear fellow-participants,

Although not a health specialist myself I think the discussion paper gives us convincing data to get really concerned about whether to keep pushing for urban agriculture. I think we should not be discouraged but there is obviously a big job for all local health inspectors in the world: educating the stakeholders and organizing mitigating measures. The facts presented can easily be (and in many cases already are) turned into clear leaflets and videos for penetrating, continuous education.

Some of the facts are contested, however, and there are also persistent myths (like the maize / banana-and-malaria case just mentioned by Jo Lines) which some local authorities present as 'facts'. An interesting, different case was studied in the city of Ouagadougou (Burkina Faso), where a Swiss-Burkinabe team found that urban gardeners working next to drains of the central hospital know very well about the health risks and experience many of the related health problems, but have their own theory about why they got ill which has nothing to do with pathogenes in the water they use. They reject 'western' medical science. I hope that these researchers (Ouedraogo and Cisse of the University of Ouagadougou and Odermatt, Maystre, Wyss and Tanner of the Swiss Tropical Institute in Bale and the Environmental Engineering Institute in Lausanne) will share their experience with us.I read their report in Info-CREPA (Ouagadougou) No.23 of spring 1999

I also would like to comment on the monitoring and certification issue mentioned in the first part of the discussion paper. In most cities the agencies that are supposed to do that are very weak, lacking the necessary manpower, equipment, labs and political backing. I also found it interesting that the paper mentions certification of safe production AREAS rather than of the products or the farmers. This seems an important tool to help urban planners deciding which agricultural land to preserve and which to convert. However, for the consumers it is the actual safety of the food that counts.

Greetings,

Leo van den Berg
(Alterra, Wageningen University & Research Centre)
e-mail: l.m.vandenberg@alterra.wag-ur.nl

6. From: Jacky Foo (IBS)
Date: August 24
Subject: re-use of wastewater

I want to make some remarks regarding the discussion paper: Urban and Periurban Agriculture, Health and Environment. (Henk de Zeeuw & Karen Lock), regarding
II a. Contamination of crops with pathogenic organisms by re-use of urban organic solid wastes and
II b. Irrigation with improperly treated wastewater.

Comment 1: Liquid waste from domestic sewage is widely used for irrigation and fertilisation of field crops, perennials and trees, biogas production, and fish ponds. A large part of the wastewater used is untreated or poorly treated.

While I support the concern of health risks associated with the use of wastes, I also agree with Furedy (1996) that perceived health risks of the re-use of urban wastes in agriculture are overstated and Armar-Klemesu et al. (1998) that the major sources of bacterial contamination of fresh vegetables may draw from the distribution, handling and marketing system rather than from production.

Comment 2: Prevention and control measures suggested in the literature: ....(cut).... - Farmer education on management of health risks (for workers and consumers) associated with re-use of waste in agriculture, - Consumer education (scraping and washing of fresh salads; eating only well-cooked crops, meat and fish from wastewater-fed crops, animals and ponds). - Fish farmer education regarding precautions in the management of wastewater-fed fish ponds. Farmer education is very important and I feel this is a practical, cost-effective and realistic approach.

Comment 3: Regarding the use of sewage to fertilise fish-pond water, there is an on-going discussion on this topic since 16th August at http://segate.sunet.se/archives/et-w1.html

The discussion highlighted the integrated bio-system (IBS) approach in using sewage and provided 3 examples.

The approach: instead of using raw sewage or anerobically digested sewage directly to fertilise fish-pond water for fish food production, the approach is to use sewage to grow aquatic plants or algae in separate shallow basins. The aquatic biomass is then used as fish feed. This system also improves fish yield per unit pond area because of reduced competition for dissolved oxygen particularly at night.

Case Study 1 : Mirzapur Farm, Bangladesh (since 1985). Three stabilisation ponds from an failed project for treating sewage were converted into fish ponds. Raw sewage (125-270 m3 / day) from community of about 3000 inhabitants, collects at a sedimentation pond before the wastewater (containing 45,700 cfu/ml total coliform) is pumped into a plug-flow canal covered with duckweed. It takes 22 days to reach the outlet of the canal and the effluent has less than 100 cfu total coliforms per ml (within WHO standard for water quality of water to be discharged into receiving body). Sludge and water used for growing bananas.

Ref:
(a)http://www.ias.unu.edu/proceedings/icibs/ibs/ibsnet/e-sem-rose.html
(b) Sascha Iqbal. 1999. Duckweed aquaculture - Potentials, Possibilities and Limitations for Combined Wastewater Treatment and Animal Feed Production in Developing Countries. SANDEC Report No. 6/99.

Case Study 2: Montfort Boys Town Vocational School, Suva, Fiji (since 1995) UNU / IAS IBS project in, Suva Fiji adds anaerobically digested hog manure into shallow algal basins. The algal "soup" is then flushed into a fish pond. Data on total coliforms is not available but it is expected that anaerobic digestion and sunlight will reduce the number of total coliforms. Pond water is used as irrigation water in vegetable garden. The fish and vegetables feed 140 residential students in a vocational school for disadvantaged youths.

Ref:
http://www.ias.unu.edu/proceedings/icibs/ibs/info/fiji

Case Study 3: ECO-FARM, Samoa (in planning - 2001) An IBS designed to accept 15-35 m5 of septage per day that is currently dumped in unlined trenches in an open dump. Septage/sewage will first be anaerobically digested, then it is added into a plug-flow canal of aquatic plants (duckweed and azolla) and mosquito fish before going into a pond. Aquatic plants and mosquito fish will be used as duck feed. Washwater contain duck manure from concrete floor is collected and also directed into the biogas digesters. I anticipate that this IBS can also produce effluent of low total coliform number.

Ref:
http://www.ias.unu.edu/proceedings/icibs/ibs/info/samoa/ecofarm

Integrated bio-systems are cost-effective because they generate income and treat wastewaters at the same time.

I hope the information is useful.

Regards

Jacky Foo
Coordinator-IBSnet
Integrated Bio-Systems Network
http://www.ias.unu.edu/proceedings/icibs/ibs/ibsnet
http://segate.sunet.se/archives/et-w1.html

7. From: Pay Dreschel
Date: August 25
To: 'Urban-Health-L@mailserv.fao.org'
Subject: hard data,re-use of waste water (coliforms / heavy metals), use of poultry manure,pesticides, monitoring

Dear participants,

My name is Pay Drechsel. I am coordinating an IBSRAM project on UPA and organic waste recycling in different cities in Ghana.

The current discussion in this sessions shows that there are many papers / statements on potential risks while hard data are often lacking. In a paper we prepared with colleagues from the Kumasi University (UST) we tried to summarize data from Accra and Kumasi on environmental / health risks of UPA. In summary, we found a large range of data on water pollution in the cities, that is water actually used for irrigation in UPA. In some cases, it is likely that UPA contributes to water pollution but this is a minor contribution as compared with other (household) sources. The pollution varied between different water bodies (drains, streams, etc.) and to a large extent between different times or years of sampling (which makes permanent monitoring necessary and is a strong argument against snapshot studies). Especially drains and streams are highly polluted with faecal coliforms. Heavy metal analysis, on the other hand, showed acceptable levels in nearly all cases. The use of polluted irrigation water resulted in vegetable contamination with coliforms as analysed in Accra and Kumasi by different working groups. Additional use of poultry manure increased the contamination level. This last part falls under the responsibility of the UPA farmer in contrast to general water quality.

We do not agree with the comment by Jacky Foo on waste-water re-use that the distribution, handling and marketing system is much increasing the risk of food contamination. At least our data and those (Jacky referred to) of Margaret Armar-Klemesu et al. (1998) do not support this (although the discussion in Margaret's paper goes this way, her data give another picture and she noticed this later on; pers.communication). If the perceived health risks of the re-use of urban waste water in agriculture are overstated will thus depend on the household behaviour, i.e. if the vegetables are carefully washed if eaten raw. With regard to other inputs used in UPA we have to consider the risk of heavy metal contamination when using compost made from urban waste. In Accra, the data available did not show any alarming concentrations. However, these were snapshot analyses from different years, thus a regular monitoring would be preferred for more security.

With regard to poultry manure, we found high coliform counts in the manure used by UPA farmers. We also expect pesticides residues due to bird treatment with insecticides, however, we have no related data. Soil and water eutrophication through poultry manure is likely in vegetable production areas with high application rates, but again data are not available. With regard to pesticide use, there are several reports that careless application of pesticides has been posing various health problems to farmers in Ghana ranging from skin rashes and skin irritations to sexual disability and even the death of children through mishandling of insecticides. However, all this is not a problem typical for UPA, but for all crop production areas in the country where pesticides are used.

An increased Malaria risk through UPA was not discussed and might not be important in and around our cities as there is no significant rice production taking place. 99% of the rice consumed in Kumasi comes from Asia and US.

We concluded that peri-urban and urban vegetable production often takes place under hazardous conditions, for example, with respect to the quality of irrigation water. Besides more education of vegetable growers on the safe use of inputs, farmers' access to clean water should be given more attention.

It is certainly true that the availability of hard data indicates areas of impact which reached scientific (and often also public) awareness. However, absence of hard data or investigations does not mean that other problems are negligible. Often the analytical capacity, for instance to detect pesticides, is not available.

Reference:

Mensah, E., Amoah, P. Drechsel, P. and R.C. Abiadoo. 2000. Environmental concerns of urban and peri-urban agriculture: Case studies from Accra and Kumasi. In: Drechsel, P. and D. Kunze (Eds.) Waste Composting for Urban and Peri-urban Agriculture - Closing the rural-urban nutrient cycle in sub-Saharan Africa. CABI-IBSRAM-FAO (in press)

Pay Drechsel
International Board for Soil Research and Management (IBSRAM)
Africa Office c/o KN-UST, Kumasi, Ghana
Tel / Fax: (0)51-60206,
email: ibsram@africaonline.com.gh

8. From: Jacky Foo
Date: August 25
Subject: impacts of food handling and marketing

Pay Drechsel wrote: We do not agree with the comment by Jacky Foo on waste-water re-use that the distribution, handling and marketing system is much increasing the risk of food contamination.

Hello Pay

In the discussion paper provided by Henk de Zeeuw and Karen Lock, they wrote:
>Furedy (1996) points out that official attitudes towards the health risks associated with re-use of urban wastes have >historically changed with necessity. Furthermore, she believes that perceived health risks of the re-use of urban wastes in >agriculture are overstated and that regulations of waste re-use are frequently outdated or lack comprehensiveness. Armar-Klemesu >et al. (1998) indicate that the major sources of bacterial contamination of fresh vegetables may draw from the distribution, handling >and marketing system rather than from production.

Note: in the forwarded copy of my message by Henk, all the quotation signs I used i.e. ">" were unfortunately removed and this does cause a difficulty in recognising the authorship.

I have not read Armar-Klemesu's paper but I do find that the statement:
>major sources of bacterial contamination of fresh vegetables may draw from the distribution, handling and marketing system >rather than from production.

When fresh vegetables are sold on road side stores or on the pavement itself, as in the cases I have seen in Manila and in Apia (Samoa), they are constantly watered to prevent dehydration of the leaves due to heat. Water will keeps the vegetable moist, however it also causes the vegetables (especially the petiole areas) to rot quickly with the growth of bacteria. You will see this when the sellers peel of the rotting portions of vegetables by the end of the day.

Rotting is enhanced by damage during handling. e.g. the Central Food depot of Mexico City (Central de Abastos) receives 24,000 tons of food products daily. At the same time it discards about 800 tons of it due to damage or decay. Damaged vegetables also quickly get contaminated.

(http://www.ias.unu.edu/proceedings/icibs/ic-mfa/losada)

Drechsel, P. and D. Kunze (Eds.) Waste Composting for Urban and Peri-urban Agriculture - Closing the rural-urban nutrient cycle in sub-Saharan Africa. CABI-IBSRAM-FAO (in press)

Please keep me informed when this book becomes available. Thank you

Regards

Jacky Foo
Coordinator-IBSnet
Integrated Bio-Systems Network
http://www.ias.unu.edu/proceedings/icibs/ibs/ibsnet
http://segate.sunet.se/archives/et-w1.html

9. From: Pay Drechsel
Date: August 25
Subject: Impacts of food handling and marketing

The reaction of Pay Dreschel on the comments of Jacky Foo regarding impacts of food handling and marketing

Dear Jacky,

You are right. There are many potential sources of contamination in the marketing system and marketing / handling is certainly different at different locations. However, we were looking for some hard data from our region and could only refer to those from Accra and Kumasi where research teams compared vegetable samples from farms and markets. And both studies - surprisingly - do not indicate a significant additional contamination from the market. It is unfortunate that Margaret had no time to adjust the text in her "et al." article. In fact, also in Ghana, market women wash their products (with exception of tomatoes) usually twice a day. On the Central Market in Kumasi they use the same water (bucket) for this procedure for all vegetables and over the whole day! And still our data show that the contamination levels remain similar to those at the farm gate (which are of course already quite high). But as I said, that are just two case studies, maybe with insufficient repetitions, and many other might show a different picture.

Best regards

Pay
International Board for Soil Research and Management (IBSRAM)
Africa Office c/o KN-UST, Kumasi, Ghana
Tel / Fax: (0)51-60206,
email: ibsram@africaonline.com.gh