The addition of vitamin C to refugees' water supply has often been suggested as a possible immediate intervention in times of emergency. Water is trucked in and stored in containers, usually rubber-lined tanks, while metal containers are also used at the household level. Iodine and chlorine are usually added to the water before distribution. Harrell-Bond and others (1989) have stressed the instability of the vitamin, especially when in contact with iron and when stored at the ambient temperature encountered in semi-arid regions.
Vitamin C in an aqueous solution tends to undergo rapid oxidation due to atmospheric oxygen (air) and when it comes in contact with metals, e.g. iron and copper. If the water has a high iron content the stability of the vitamin is low. The pH of the water is also important, the vitamin being most stable when the pH is 3-5.5. Vitamin C reduces many organic reducible substances such as iodine. The interaction of vitamin C with chlorine and iodine depends on the concentration of these two elements in the water. Stability trials have shown that 50-200 ppm vitamin C added to chlorinated drinking water (0.3 mg/l) is rapidly degraded within a few hours (Roche, personal communication).
Hornig and Moser (1981) reported that vitamin C in tap water kept at room temperature becomes more stable with increasing concentrations of vitamin C and that it is rapidly oxidized below a concentration of 100 mg/l water. After one day (24 hours) at room temperature a solution with 10 mg vitamin C per litre water had zero vitamin C left, a solution with 100 mg vitamin C per litre water had 2%-3% of the vitamin left, whereas a solution with 500 mg per litre still had 50% of the initial vitamin C content. Adding sugar to water (about 6%-12%) increases the stability of vitamin C in water.
Vitamin C powder has been added to jugs of water in schools in the former Yugoslavia shortly before distribution to children (Buzina, personal communication). The children liked the slightly sour taste. Ryffel (Roche, personal communication) stated that vitamin C can be added to bottled water and is already the case with soft drinks and fruit juices. As an alternative to supplementation with vitamin C tablets in the former Yugoslavia, orange juice powder enriched to provide 350 mg of vitamin C per 100 g was distributed in the general ration. At the household/individual level, the powder was added to drinking-water.
Returning to refugee situations, especially in Africa, if vitamin C is to be added to large water tanks, several issues will have to be investigated:
• What can be done to overcome the degradation of vitamin C in chlorinated water?
• When would it be feasible to add vitamin C powder to water tanks and how soon should the water be consumed?
• How is the water distributed from the main tanks to the household? Should metal pipes or taps be used?
• How is the water stored at the household level?
• How much of the water is consumed and how much is used for other purposes, e.g. washing?
• How much vitamin C is left after the water has been boiled or used for cooking?
• How acceptable is the "new substance" in the water, from a psychological standpoint as well as in terms of taste?
Water fortification could also take place at the community or household level depending on how camps are organized and on the motivation of refugees.
Vitamin C powder added to water would have to be mixed well to ensure that it is adequately dissolved. Although adding plain effervescent vitamin C tablets to water would not require mixing, the major drawback is that tablets are highly sensitive to humidity; once damp they do not mix well in water. Effervescent tablets are available on the European market packed in aluminium foil and in aluminium or plastic tubes of about 10 tablets. Larger quantities could be packed in plastic. Lastly, effervescent tablets cost more than plain vitamin C powder.