Vegetable production with contaminated water has been identified as one of the mechanisms of disease spread, including the spread of cholera in Latin America in 1991-92. In developing a successful programme to ensure consumer protection, both the crop and the water supply must be considered.
The strong and successful cholera eradication programme in Chile in 1992 resulted from a heightened awareness of product quality by the consumer. This resulted, in part, from a strong public education programme on disease control and an informal programme by farmers where they placed labels on their produce which declared their vegetables were produced with safe water. This served to focus the consumer on the quality of the produce and the quality of the water used. The emphasis of the consumer and the producer in this case was on prevention. It is recommended that any certification programme also promote prevention as its primary focus.
There are two approaches to certification that focus on prevention: (1) certifying the quality of produce, or
(2) certifying that the product was produced in a safe environment. Controlling the quality of the produce (option 1), focuses prevention on the crop rather than on where and how it was produced as is done in option 2. Under option 1, assessment and control is done after the crop is produced and harvested. This is a high-risk programme not only for all producers but also for the group that is responsible for making the product inspections.
Conducting microbial testing of the crop is a highly specialized programme that requires sophisticated laboratory facilities and highly trained staff. Both of these are lacking in most developing countries. Producing marginal results or inaccurate results could lead to the programme having little or no credibility. The cost of operating and maintaining a continuous testing programme for the annual peaks in vegetable production will also mean maintaining a large cadre of trained staff and laboratory space to accommodate these peak times making the cost per sample tested very high.
There is considerable risk also to the agency responsible for conducting the testing. The product testing system must be highly efficient as most microbial tests
require 24-72 hours to complete. This analytical time must be added to any sampling and data processing time, thus any delays would put the produce in jeopardy of spoilage. Most of the testing would be conducted on perishable fruits and vegetables where even a 24 -hour delay may mean the loss of the crop. The producers are also at considerable risk for their investment. If crop testing shows contamination, the crop may have to be destroyed as there likely would not be sufficient time to retest the crop before its quality and durability are lost. Any delays in the testing programme would put the crop at considerable risk. Most vegetable farmers in developing countries are small farmers where a crop loss might mean the total loss of income for that year or loss of a farming business. Because of the high risk, the high cost, and the lack of well defined methods that ensure all crops are contamination free (option 1), this type of programme is not recommended. The most effective programme, at the present time, is to develop a certification programme that emphasizes prevention of contamination during crop production by developing safe production areas and ensuring the consumer that the product came from a clean area (option 2). A programme that focuses on safe production methods significantly lessens the risk to any user of the produce as well as to the producer. This type of focus has already resulted in a significant
reduction of gastrointestinal diseases in the Santiago area of Chile as a result of an informal programme already started there by producers (Figure 3).
A certification programme should promote production of vegetables needed by the country but with the recognition that disease outbreaks have been caused by unrestricted irrigation with contaminated water. Experience shows the primary source of contamination in recent disease outbreaks was the water used for irrigation. Because of this, a certification programme should focus on the source of water used in production. The intent is to promote safe production with the ability to abandon the programme when the source of water contamination is controlled. It is recommended that the programme be conducted in close cooperation with National and Regional Health Services.
If the focus is on the water supply, a four-step process is suggested to ensure sufficient quantities of safe vegetables are available for the domestic market. The four-step process is:
(1) certify the water used in production (this step significantly reduces contamination risk);
(2) establish areas of clean water for vegetable freshing (this step reduces the threat of secondary contamination from use of poor quality water during harvest and transport);
(3) certify the water used in packing and processing the vegetables (this step reduces secondary contamination in packing and handling); and
(4) test a selected number of crops and certify the absence of contamination (this step assures the consumer that the product has been tested and found to be low risk).
An effective certification programme can begin with just the first step. Each new step would be taken only if:
the spread of diseases by raw vegetables is not improving; a there is evidence that one of the other steps in the process is contributing to the problem;
there are sufficient resources to operate the next part of the programme effectively.
In order for the agricultural and health authorities to control cropping and carry out an effective nationwide or regional water quality certification programme, there needs to be a sound information base for decision making (see section Evaluation of irrigation water quality).
The goal of a water quality monitoring and certification programme is to identify large irrigated areas that can be safely used to meet national vegetable production needs.
To carry out this programme, a staff needs to be developed who can plan, execute and interpret a water quality monitoring programme using the guidelines previously discussed in this document. This professional team should be utilized to establish the sampling and analytical procedures, define the monitoring points and conduct the initial area-wide monitoring assessment.
Having centralized control of the monitoring programme would help to: control the quality of information that is used in developing national production policies;
set priorities on information development, based upon the importance of vegetable production within each region; and
develop a high level of credibility in managing disease potential. The water quality monitoring programme should aim to:
develop a legal basis for decisions;
establish an initial basis for a certification programme to minimize the amount of private resources that must be involved; and
determine the amount of private financing that will be needed in the future.