Nasty, Brutish, and Dirty

Monday, February 01, 1999
Ecologist David Pimentel and his graduate students at Cornell pulled together statistics from the World Health Organization in Geneva, the Centers for Disease Control and Prevention in Atlanta, and other sources to analyze the effects of population growth and environmental degradation on human disease. Overall, they report, some 40 percent of all deaths can now be attributed to various environmental factors. A few of their findings:


HUMAN ACTIONS
Building Egypt's Aswan High Dam.
ENVIRONMENTAL EFFECTS
Expanded the habitat for snails that host the flatworm Schistosoma mansoni, second only to the parasite that causes malaria in the number of people it kills worldwide.
DISEASE INCIDENCE
Proportion of people in the Nile Valley with schistosomiasis increased from 5 percent in 1968 to 77 percent in 1993.


HUMAN ACTIONS
Deforestation and doubling of some African populations every 20 years.
ENVIRONMENTAL EFFECTS
More people living near areas favorable for breeding mosquitoes.
DISEASE INCIDENCE
From 1970 to 1990, malaria incidence in Rwanda increased eightfold. Malaria kills about 2.7 million people each year.


HUMAN ACTIONS
Global use of pesticides increased from 110 million pounds a year in 1945 to 5.5 billion pounds in 1995. Most modern pesticides are ten times more toxic than those used in the 1950s.
ENVIRONMENTAL EFFECTS
Increased contact with toxic chemicals.
DISEASE INCIDENCE
There were 3 million cases of pesticide poisoning in 1992. In California, 40 percent of children working in agricultural fields show signs of pesticide poisoning.


HUMAN ACTIONS
The number of automobiles is growing three times faster than the human population. Fossil-fuel emissions and industrial pollutants are also increasing.
ENVIRONMENTAL EFFECTS
Air pollution levels in the world's 20 largest cities exceed WHO guidelines. Fewer than 1 percent of 500 Chinese cities surveyed have clean air. Depletion of ozone in Earth's atmosphere.
DISEASE INCIDENCE
Respiratory diseases are the leading cause of death in China. The incidence of skin cancer in the United States jumped from 10,000 cases in 1975 to 40,000 in 1996.


HUMAN ACTIONS
Global population expansion.
ENVIRONMENTAL EFFECTS
Less cropland per person.
DISEASE INCIDENCE
More than half the world's population suffers from malnutrition.


HUMAN ACTIONS
Suburban expansion.
ENVIRONMENTAL EFFECTS
Close contact with white-tailed deer populations and thus the deer tick, which carries the bacterium Borrelia burgdorferi.
DISEASE INCIDENCE
Lyme disease, discovered in 1976, now affects 12,700 people a year in the United States.

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