On average, an infant of six months drinks almost 10 times more water than the average adult, inhales almost twice the volume of air and, between the ages of one and five, eats three to four times more food per unit of body weight than an adult. Such consumption means children have a high degree of exposure to the environment, which makes them extremely prone to environment-related morbidity and mortality. According to estimates of the World Health Organisation (WHO), which has declared a 'healthy environment for children' the theme of this year's World Health Day (7 April), over five million children die every year due to illnesses and other conditions caused by the environment in which they live, learn and play.
The nature of a child's susceptibility is closely associated with the socio-economic conditions of the country in which he or she lives. Poor countries are often unable to provide adequate sanitation and drinking water, and children are at high risk to develop health problems as a result. The toxins and the pathogens with which a child comes in contact thus, disrupt normal physiology and biological functioning. Research suggests that over 40 percent of the global disease burden arising from environmental factors may fall on children under the age of five, who constitute only about 10 percent of the world's population.
Among water borne diseases, diarrhoea is the prime killer. By the WHO's numbers, the disease claims 2.2 million lives every year and is responsible for 12 percent of child deaths under five years of age in developing countries. In rural north India, over half of all diarrhoeal deaths occur in children below five. Malnourished children are more susceptible to pathogens. "Over half of the children under the age of five years in India are moderately or severely malnourished while 30 percent newborn children are significantly underweight", says the National Human Development Report 2001 of the Planning Commission of India.
Roundworm, hookworm, tapeworm and whipworm infections couple with malnourishment in tropical countries to devastate bodies. In rural India, about 20 percent of outpatient morbidity results from worm-related ailments and, globally, about 400 million children of school-going age are afflicted with the problem. Fluoride and nitrate groundwater contamination affects around six million children in India, and in both Bangladesh and India the presence of arsenic in groundwater is a persistent problem.