Page 383 - Environment: The Science Behind the Stories

4.5
4.0
Respiratory and Other
digestive diseases 3.5

3.0
Maternal
and 8.6%
perinatal Infectious 2.5
conditions 10.3% diseases
23.4% Annual deaths (millions) 2.0
6.3%

Injuries 9.8% Cardiovascular 1.5
diseases 1.0
12.6% 29.0%
0.5
Cancers
0
Respiratory Diarrheal AIDS TB Malaria Childhood
infections diseases diseases
(influenza, (measles,
pneumonia, etc.) pertussis,
tetanus, etc.)
(a) Leading causes of death across the world (b) Leading causes of death by infectious diseases
Figure 14.3 Infectious diseases are the second-leading cause of death worldwide. Six types of
diseases account for 80% of all deaths from infectious disease. Data from World Health Organization, 2009. World
health statistics 2009. WHO, Geneva, Switzerland.

In the United States and other developed nations, lifestyle eat more. BPA exposure in mice has also been found to cause
trends are altering the prevalence of noninfectious disease in blood insulin levels to be twice that of unexposed mice. This
ways both good and bad. In the last two decades, the percentage excess of insulin can, over time, desensitize the body to insu-
of Americans who smoke cigarettes has dropped by 42%. But as lin, leading to weight gain and type 2 diabetes.
we exercise less and eat fattier diets, the percentage of Americans Although infectious disease accounts for fewer deaths than
who suffer obesity has more than doubled (Figure 14.4). noninfectious disease, infectious disease robs society of more
Surprisingly, elevated levels of BPA have been linked to obe- years of human life, because it tends to strike people at all
sity. Studies have found that BPA exposure in mice elevates ages, including the very young. The World Health Organization
the production of fat cells in developing embryos and leads (WHO) estimates that of all the years of life lost to deaths each
to the storage of more fat in organisms, even if they do not year, infectious disease takes 51%, whereas noninfectious dis-
ease takes 34%. Decades of public health efforts have lessened
35% the impacts of infectious disease and even have eradicated some
diseases—yet other diseases are posing new challenges. Some
Prevelance in U.S. population 25% them (pp. 226–227). Others, such as tuberculosis and strains of
30%
diseases, such as acquired immunodeficiency syndrome (AIDS),
Obesity
Smoking
continue to spread globally despite concerted efforts to stop
malaria, are evolving resistance to our antibiotics, in the same
20%
way that pests evolve resistance to our pesticides (p. 273).
15%
Social and environmental factors can
10%
5%

0 influence the spread of infectious disease
In our world of global mobility and dense human populations,
1990 1993 1996 1999 2002 2005 2008 2011 novel diseases (and new strains of old diseases) that emerge in
Year one location are more likely to spread to other locations, even
Figure 14.4 The prevalence of smoking has decreased in worldwide. A pathogen can now hop continents in a matter of
the United States in the past 20 years, but obesity is on the hours by airplane in its human host. As a result, some diseases
rise. Data from United Health Foundation, 2011. America’s health rankings, have moved into new areas.
2011 edition. Minnetonka, MN. Recent examples include severe acute respiratory syn-
The population of the United States in mid-2011 was drome (SARS) in 2003, the H5N1 avian flu (“bird flu”) start-
approximately 312 million people. Using the figure, estimate ing in 2004, and the H1N1 swine flu that spread across the
382 the number of Americans in 2011 who were (a) obese and (b) smokers. globe in 2009–2010 (Figure 14.5). Diseases like influenza,

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