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Pollution causes four in 10 deaths, survey finds

Aug. 14, 2007
Courtesy Cornell University 
and World Science staff

Some 40 per­cent of deaths world­wide are caused by wa­ter, air and soil pol­lu­tion, a study has found.

Such en­vi­ron­men­tal de­grada­t­ion, cou­pled with the growth in world popula­t­ion, are ma­jor causes of a re­cent rap­id in­crease in dis­eases re­ported by the World Health Or­gan­iz­a­tion, said the re­search­er.

In 1798, the econ­o­mist Thom­as Mal­thus pre­dicted that as hu­man pop­u­la­tions ex­plod­ed, avail­a­ble re­sources would di­min­ish and star­va­tion would en­sue. The idea was wide­ly rid­i­culed, and often still is. But a new study claims that today, as the pop­u­la­tion grows, re­sources are strained and mal­nu­tri­tion is on the rise.


Both fac­tors con­trib­ute to the mal­nour­ish­ment and dis­ease sus­cep­ti­bil­ity of 3.7 bil­lion peo­ple, added the in­ves­ti­ga­tor, Da­vid Pi­men­tel of Cor­nell Un­ivers­ity in Ith­a­ca, N.Y. The find­ings ap­pear in the early on­line is­sue of the re­search jour­nal Hu­man Ecol­o­gy and are slat­ed for pub­lica­t­ion in the De­cem­ber print is­sue.

Pi­mentel and some grad­u­ate stu­dents ex­am­ined da­ta from more than 120 pub­lished pa­pers on the ef­fects on hu­man dis­ease of popula­t­ion growth, mal­nu­tri­tion and var­i­ous kinds of en­vi­ron­men­tal de­grada­t­ion.

“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, he added.

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 oth­er 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 var­i­ous tox­ins. 

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 con­clud­ed. He and his co-authors called for com­pre­hen­sive and fa­ir popula­t­ion poli­cies and more con­serva­t­ion. “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,” they wrote.


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Some 40 percent of deaths worldwide are caused by water, air and soil pollution, a study has found. Such environmental degradation, coupled with the growth in world population, are major causes of a recent rapid increase in diseases reported by the World Health Organization, said the researcher. Both factors contribute to the malnourishment and disease susceptibility of 3.7 billion people, added the investigator, David Pimentel of Cornell University in Ithaca, N.Y. The findings appear in the early online issue of the research journal Human Ecology and are slated for publication in the December print issue. Pimentel and a team of 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. “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 other 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 various toxins. 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 concluded. He and his co-authors called for comprehensive and fair population policies and more conservation. “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,” they wrote.