A study published in 2007 by Cornell University purports air, water and soil pollution cause 40 percent of the world's deaths because this pollution increases the spread of human disease. Factors relating to the deaths include malnourishment, lack of clean water, inadequate sanitation in urban settings, toxic chemicals released into the air, contaminated soil and soil erosion.
The study claims 1.2 billion people lack clean drinking water, which is a direct factor in as many as 2.7 million deaths. Lack of clean water leads to unsanitary conditions, and these conditions kill 5 million people annually. Poor water causes 5.3 percent of deaths worldwide as of 2003. Population increases exacerbate waterborne diseases.
Air pollution contributes to birth defects, cancer, immune-system problems and other health difficulties. In March 2014, the World Health Organization estimated seven million people died from air pollution in 2012, which amounts to one in eight deaths worldwide. The WHO indicates air pollution is the "largest single environmental health risk." In China alone, 1.2 million premature deaths were linked to air pollution in 2010, about 40 percent of the worldwide total of air pollution deaths at the time.
The global burden of disease caused by pollution is roughly 8 to 9 percent, notwithstanding developing countries where there is little infrastructure to ascertain the affects of pollution on health. Pollution takes its toll on human beings in terms of disabilities that limit normal activities and possibly lead to premature death.