One hundred and fifty million children, or one in three, in the developing world are seriously malnourished (United Nations Development Program 1990). This includes 38 million children underweight, 13 million wasted, and 42 million stunted. In addition, 42 million children are vitamin A–deficient (West and Sommer 1987), 1 billion people, including children, are at risk of iodine-deficiency disease (Dunn and van Der Haar 1990), and 1.3 billion have iron-deficiency anemia (United Nations 1991).
Malnutrition, whether undernutrition per se or a specific micronutrient deficiency, is usually the result of an inadequate intake of food because households do not have sufficient resources. In a review of the income sources of malnourished people in rural areas, J. von Braun and R. Pandya-Lorch (1991) found that among households with a per capita income below $600 (U.S.), there was a close relationship between household food security and the nutritional status of children.
The problems associated with nutritional deprivation are compounded when access to sanitation is limited, because poor sanitation and hygiene results in increased morbidity. This condition is often accompanied by a reduction in food intake at the very time when energy and nutrient requirements are high. About one-third of the populations of developing countries has access to sanitation, and just over half have access to safe water, but there are large urban–rural differences. Ease of access to water is 48 percent lower in rural areas than urban areas, and overall access to sanitation is 77 percent lower in rural areas (United Nations Development Program 1990).