The technology of modern diapers has evolved through extensive research over the last 40 years. The idea was to have a material that absorbs the water (urine of the baby) rapidly and that holds water in large enough quantity to minimize mother's work of frequent cleansing of the infant.
The earlier disposable diapers developed in 1950s consisted of crêped tissues sandwiched between a rayon inner layer and a plastic outer layer. Although highly successful, those diapers created the problem of the diaper rash as the wet diaper remained close to the skin of the baby. Also, when the baby sat on the diaper, water leaked.
Modern diapers, which keep the baby dry efficiently, measure seven by 13 inches and are seemingly simple and innocuous throwaways. However, they indeed have their own anatomy and physiology. It has three layers. The top porous layer, the middle filler and the bottom nonporous water retainer. If one dissects the diaper carefully across, and peels away the soft fabric on the top of the diaper, the liner that receives the urine, one will find a fine layer granules of polyfilm. This polyfilm is the reason the baby's bottom stays dry. The polyfilm has pores big enough to breathe, and small enough to hold water from leaking according to Bucholz, the inventor of modern diaper.1 The diapers, therefore, are also thinner and fit the babies well. More importantly, they retain the water (urine) within, thanks to the 10–15 g of super absorbent polymers (SAPs) within the diaper.
The diaper-liners are made of SAPs and microscopically appear like tightly knit fisherman's net. These polymers trap the water and can hold huge amounts of water. They can retain water albeit the urine 30 times their weight preventing leakage even under the pressure of the baby's weight. The urine arrives at a rate of 7 ml/second and may total 70 ml. The liner can clear that in 20 seconds. It took decades for scientists to develop modern diapers that keep infants dry and mothers happy. Today, the economics of diapers is no small change: annual sales are estimated to be in the order of US $3.5 billion.1 Clinical studies have also demonstrated health benefits of SAP lined diapers. These diapers keep the skin dry, significantly reducing the incidence and severity of skin rash. Also, these diapers reduce the risk of bacterial contamination by reducing the seepage of the urine and excreta.2
DIAPERS AND IMPLICATIONS FOR THE DESERTS
The above discussion begs the question: what is the connection between the dirty diaper and the dry desert? Interestingly, it is found that the same SAPs that keep the baby's bottoms dry can keep the desert soil wet. No small wonder indeed!
Water is the most important commodity in the world particularly in arid deserts of Sahara, the Middle East and elsewhere. Right now we face a global water scarcity. The Second World Forum held at Hague in the year 2000 confirmed the lack of global water resources, particularly in the arid regions of Middle East and North Africa. Common methods of exploiting the underground water for irrigation have their disadvantages: water is lost due to evaporation and infiltration during irrigation, thereby leading to wastage of the scarce commodity. To meet the needs of water in the arid deserts we needed a new technology. Help came from an unexpected quarter: the diaper! The technology that keeps the baby dry can keep the soil wet!
The diaper technology is being used to increase the moisture of the soil in barren arid lands. Many manufacturers are using SAPs to increase crop yield and to grow plants the soil conditioner ‘TerraCottem’ (TC)3 made by one company consists of water absorbent polymers and mineral fertilizers. Just as the SAPs in diapers prevent a liquid from escaping, the chemical (SAP) in soil helps it to retain water. According to the New York Times the United Nations Convention to Combat Desertification,3 TerraCottem is being used to prevent soil erosion in Iran and Krygstan. Similarly, other products are being used to grow flowers in the deserts. Thus, the use of diaper technology has implications not only for solving the problem of global water scarcity but also for increasing agricultural productivity. The innovative products are known to increase crop yield by 25 to 100% while cutting water use in half depending on the crop and terrain.
Studies in this technology have been conducted in Senegal, Nigeria, Pakistan, India and China. The cost, at $ 2/pound, is still expensive to most farmers in developing countries. Lowering the cost of diaper technology would mean that one can go anywhere in the world and use the little water that is available, which sometimes falls from the sky for free instead of investing in very expensive irrigation projects, says Bucholtz the innovator of the modern diaper.
Now that the diaper specialists have found a way to make the diaper absorb the water and retain it until disposed, the future engineers have to develop appropriate and inexpensive technology to hold the limited water for long in the soil and release it efficiently to grow plants and raise crops in the deserts of Africa and around the globe.
Prasad HRY, Srivatsava P, Verma KK . Diapers and skin care: merits and demerits. Indian J Pediatr 2004;71:907–908.
Now Diaper Technology Takes on a Desert (Otto Pohl, June 20, 2004), New York Times.
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Vidyasagar, D. Global Notes: Diapers and the Deserts. What is the Connection?. J Perinatol 25, 747–748 (2005). https://doi.org/10.1038/sj.jp.7211374