About 40 percent of deaths worldwide are caused by water, air and soil pollution, concludes a Cornell researcher. Such environmental degradation, coupled with the growth in world population, are major causes behind the rapid increase in human diseases, which the World Health Organization has recently reported. Both factors contribute to the malnourishment and disease susceptibility of 3.7 billion people, he says.
David Pimentel, Cornell professor of ecology and agricultural sciences, and a team of Cornell graduate students examined data from more than 120 published papers on the effects of population growth, malnutrition and various kinds of environmental degradation on human diseases. Their report is published in the online version of the journal Human Ecology and will be published in the December print issue.
"We have serious environmental resource problems of water, land and energy, and these are now coming to bear on food production, malnutrition and the incidence of diseases," said Pimentel.
Of the world population of about 6.5 billion, 57 percent is malnourished, compared with 20 percent of a world population of 2.5 billion in 1950, said Pimentel. Malnutrition is not only the direct cause of 6 million children's deaths each year but also makes millions of people much more susceptible to such killers as acute respiratory infections, malaria and a host of other life-threatening diseases, according to the research.
Among the study's other main points:
At the same time, more microbes are becoming increasingly drug-resistant. And global warming, together with changes in biological diversity, influence parasite evolution and the ability of exotic species to invade new areas. As a result, such diseases as tuberculosis and influenza are re-emerging as major threats, while new threats -- including West Nile virus and Lyme disease -- have developed.
"A growing number of people lack basic needs, like pure water and ample food. They become more susceptible to diseases driven by malnourishment, and air, water and soil pollutants," Pimentel concludes. He and his co-authors call for comprehensive and fair population policies and more conservation of environmental resources that support human life.
"Relying on increasing diseases and malnutrition to limit human numbers in the world diminishes the quality of life for all humans and is a high-risk policy," the researchers conclude.
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