Cellophane bags and clean water: A novel way of producing safe therapeutic milk and ORS?

Most people will have come across cellophane, its the packaging for many sweets, pies and other goodies. In the laboratory it has long been used for dialysis of salt solutions during which the membrane acts as a filter, sieving out molecules according to their size. The properties of cellophane were recognised some years ago as having a potential for producing clean food and water in situations where bacterial and viral contamination are common. The idea was then taken on and developed by a commercial company called UCB Osmotics. What they have produced is best described as a bag, in which the dry components of therapeutic milk or ORS are contained. In principle, when this bag is placed in contaminated water the water enters the bag due to osmosis but bacteria and viruses do not. This happens because of the sieve-like quality of the cellophane which allows in the small water molecules but keeps out the larger bacteria and viruses. Does it work? Well yes, in lab trials in Bangladesh and the UK the membrane does keep out Ecoli and the ORS and milk produced is of good quality. Does it have an application in emergencies? This remains to be determined and as part-way to answering this we are currently organising field trials in feeding centres in Bangladesh and Tanzania. Watch this space.

For further information contact Andy Seal, Centre for International Child Health, Institute of Child Health, 30 Guilford Street, London WCJ JEH e-mail: A.Seal@ich.ucl.ac.uk