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 (available at https://www.springerlink.com/content/101592/,
to 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:
* Nearly half the world's people are crowded into urban areas,
often without adequate sanitation, and are exposed to epidemics
of such diseases as measles and flu.
* With 1.2 billion people lacking clean water, waterborne infections
account for 80 percent of all infectious diseases. Increased
water pollution creates breeding grounds for malaria-carrying
mosquitoes, killing 1.2 million to 2.7 million people a year,
and air pollution kills about 3 million people a year. Unsanitary
living conditions account for more than 5 million deaths each
year, of which more than half are children.
* Air pollution from smoke and various chemicals kills 3 million
people a year. In the United States alone about 3 million tons
of toxic chemicals are released into the environment -- contributing
to cancer, birth defects, immune system defects and many other
serious health problems.
* Soil is contaminated by many chemicals and pathogens, which
are passed on to humans through direct contact or via food and
water. Increased soil erosion worldwide not only results in
more soil being blown but spreading of disease microbes and
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.