Author: Pugh, Katherine H; Zarus, Gregory M
Date published: May 1, 2012
Editor's Note: As part of our continuing effort to highlight innovative approaches to improving the health and environment of communities, the Journal is pleased to bring back the bimonthly column from the U.S. Agency for Toxic Substances and Disease Registry (ATSDR). The ATSDR, based in Atlanta, Georgia, is a federal public health agency of the U.S. Department of Health and Human Services and shares a common office of the Director with the National Center for Environmental Health at the Centers for Disease Control and Prevention (CDC). ATSDR serves the public by using the best science, taking responsive public health actions, and providing trusted health information to prevent harmful exposures and diseases related to toxic substances.
The purpose of this column is to inform readers of ATSDR's activities and initiatives to better understand the relationship between exposure to hazardous substances in the environment and their impact on human health and how to protect public health. We believe that the column will provide a valuable resource to our readership by helping to make known the considerable resources and expertise that ATSDR has available to assist communities, states, and others to assure good environmental health practice for all is served.
The conclusions of this article are those of the author(s) and do not necessarily represent the views of ATSDR, CDC, or the U.S. Department of Health and Human Services.
Katherine (Katie) Pugh is an environmental health scientist with ATSDR. She has been with ATSDR since June 2001. Katie has a Bachelor of Science degree in biology from the University of Maryland and a Master of Science degree in environmental economics from the University of Georgia. Gregory Zarus has been an environmental health scientist with ATSDR since April 1997. He has a Bachelor of Science degree in meteorology from Millersville University and a Master of Science degree in atmospheric science and geophysics from Texas Tech University. Greg currently leads the team that assesses the health impact of environmental contamination near federal sites.
The U.S. spends the most of any nation on health - over $2 trillion every year - yet ranks 37th in overall health among nations of the world (Healthiest Nation Alliance, 2011). Over 17% of the U.S. gross domestic product was spent on health expenditures in 2009 (Centers for Medicare and Medicaid Services, 2009). As our emphasis moves to health protection through health promotion, prevention, and preparedness, it is helpful to identify the economic burden of major disease groups in order to develop and support the best evidence-based health protection strategies. In an effort to establish environmental health prevention strategy targets, we have focused this report on defining the economic burden of environmental disease in the U.S.
The Top Environmental Disease Groups in the United States
In 2006, the World Health Organization (WHO) published a report entitled, "Preventing Disease Through Healthy Environments: Towards an Estimate of the Environmental Burden of Disease." WHO defined the environment as "all the physical, chemical, and biological factors external to the human host, and all related behaviors, but excluding those natural environments that cannot reasonably be modified (Prüss-Üstün & Corvalán, 2006)." WHO produced complimentary profiles for the countries examined in the report. These profiles detailed the major disease categories that made up each country's burden of environmental disease.
WHO used the disability-adjusted life year (DALY) to measure the burden of disease in the U.S. in 2004. A DALY is a weighted measure of death, illness, and disability. DALYs are calculated as the sum of the years of life lost due to premature mortality in the population and the years lost due to disability for cases of the disease. In the U.S., 13% of the total burden of disease is attributable to the environment. This amounts to 5,662,000 DALYs and 398,000 deaths annually (World Health Organization [WHO], 2007). The attributable fraction is the decline in disease or injury that could be achieved in a given population by reducing the risk (Prüss-Üstün & Corvalán, 2006).
Many environmental exposures are preventable; therefore, ranking disease groups by DALY and focusing prevention efforts on those groups that present the largest opportunity for impact is useful. Table 1 shows the 12 diseases with the greatest burden attributable to the environment in the U.S. and their associated DALYs. Our report focuses on those disease groups most applicable to the mission of the National Center for Environmental Health (NCEH)/Agency for Toxic Substances and Disease Registry (ATSDR). The mission of NCEH/ATSDR is to serve the public through responsive public health actions to promote healthy and safe environments and prevent harmful exposures. The following disease groups that are discussed in detail in this report are shown in bold type in Table 1.
Cardiovascular disease accounts for the greatest burden of disease that is caused by the environment: 1,072,800 DALYs annually in the U. S. (WHO, 2007). Cardiovascular disease includes high blood pressure, coronary heart disease, congestive heart failure, and stroke. The estimated direct and indirect cost of all cardiovascular disease, attributable to the environment and otherwise, was $393.5 billion in 2005 (American Heart Association, 2005).
Cardiovascular disease is associated with environmental risks such as air pollution (Pope et al., 2002), occupational hazards (Steenland, Burnett, Lalich, Ward, & Hurrell, 2003), and lead exposure (Schwartz, 1995). Fine particulate-matter pollutants are strongly associated with cardiovascular mortality (Evans & Smith, 2002; Samet, Dominici, Curriero, Coursac, & Zeger, 2000).
Neuropsychiatrie disorders account for the second- greatest burden of disease caused by the environment and are responsible for an estimated 894,000 DALYs annually in the U.S. (WHO, 2007). Neuropsychiatrie disorders include Alzheimer's disease and other dementias, Parkinson's disease, multiple sclerosis, schizophrenia, epilepsy, bipolar affective disorders, depression, alcohol and drug abuse, insomnia, migraine, panic disorder, posttraumatic stress disorder, and lead-induced mild mental retardation. Many of these conditions have a small- to-moderate link to the environment or occupation (Prüss-Üstün & Corvalán, 2006). Neuropsychiatrie disorders are linked to environmental risks such as stress at work (Tennant, 2001), occupational noise (Passchier-Vermeer & Passchier, 2000), and exposure to toxic chemicals (Huang, de la Fu ente- Fernandez, & Stroessl, 2003).
The estimated combined cost of Parkinson's disease, neurodevelopmental effects, and deficits in intelligence quotient (IQ) in the U.S. amounted to between $405.709 and $625.818 billion in 1999 dollars. Weight of evidence suggested that from 10% to 50% of these annual costs, which amounted to between $41 and $313 billion, respectively, were environmentally induced (Muir & Zegarac, 2001). Muir and Zegarac stated that "it is beyond the scope of this review to factually determine what proportion of the grand total cost is attributable to environmental causes," therefore, their estimate had a very large range.
Each year's U.S. birth cohort gained an estimated $110-$300 billion in total lifetime productivity because IQ scores increased as a result of reductions in lead exposure in the U.S. between the mid-1970s and the late199Os (Grosse, Matte, Schwartz, & Jackson, 2002). One hundred percent of childhood lead poisoning cases are attributable to the environment. The estimated present value of economic losses attributable to lead exposure in the birth cohort of five year olds in 2002 was $43.4 billion annually (Landrigan, Schechter, Lipton, Fahs, & Schwartz, 2002).
Cancer (Excluding Lung Cancer)
The third- largest burden of disease due to the environment comes from cancer, excluding lung cancer. These cancers account for an estimated 625,800 DALYs annually in the U.S. (WHO, 2007).
The National Institutes of Health estimated direct and indirect cost of all cancers, including lung cancer, at $219.2 billion in 2007. $89 billion of this was for direct medical costs, $18.2 billion was for indirect morbidity costs, such as cost of lost productivity due to illness, and $112.0 billion was for indirect mortality costs, such as cost of lost productivity due to premature death (American Cancer Society [ACS], 2008). These figures include cancers believed to be caused by the environment and cancers believed to be caused by other factors.
Environmental (nonhereditary) factors, such as tobacco use, poor nutrition, inactivity, obesity, certain infectious agents, certain medical treatments, sunlight, naturally occurring carcinogenic agents in food, occupational carcinogens, and carcinogenic pollutants account for an estimated 75%80% of all cancer cases and deaths in the U.S. About 4% of cancer deaths are thought to be caused by occupational exposures and 2% by environmental pollutants (ACS, 2008). If we take the American Cancer Society's estimate that 75%-80% of cancer cases are due to environmental factors, then the total cost of all cancers caused by the environment would be approximately $164 .4-$ 175 .4 billion.
Stomach, skin, liver, bladder, breast, and nasopharyngeal cancers, as well as leukemia, all have environmental links (Woodruff, Axelrad, Caldwell, Morello-Frosch, & Rosenbaum, 1998). Benzene, specifically, causes leukemia (Agency for Toxic Substances and Disease Registry [ATSDR], 2007).
Lung cancer, the fifth-largest burden of disease due to the environment, is responsible for an estimated 357,600 DALYs annually in the U.S. (WHO, 2007). It causes the greatest disease burden of any one cancer - 13% of the burden of all cancers comes from lung cancer. In developed nations, approximately 30% of the lung cancer burden can be attributed to environmental factors (Prüss-Üstün & Corvalán, 2006).
Cigarette smoking is the greatest risk factor for lung cancer, causing 87% of lung cancer deaths. Smoking resulted in more than $167 billion in annual health-related expenses in the U.S. (ACS, 2008).
Other risk factors for lung cancer include occupational or environmental exposure to environmental tobacco smoke (ETS) (otherwise known as secondhand smoke), radon and asbestos (risk elevated by smoking), certain metals (chromium, nickel, cadmium, and arsenic), some volatile organic compounds, radiation, and air pollution (ACS, 2008).
Asthma due to the environment is responsible for an estimated 298,000 DALYs annually in the U.S. (WHO, 2007). Asthma development and exacerbation can be triggered by indoor or outdoor air contaminants such as mold, dust mites, pet and pest allergens, ETS, and air pollution (Prüss-Üstün & Corvalán, 2006).
In 2006, the estimated total cost of asthma to society (incremental direct cost and productivity costs) was $32.6 billion in 2008 dollars (Barnett & Nurmagambetov, 2011). This includes all asthma cases, not just those attributable to the environment.
The direct and indirect costs of asthma due to residential risk factors for children younger than 16 years of age were estimated to be $807 million (in 1997 dollars) annually (Lanphear, Aligne, Auinger, Byrd, & Weitzman, 2001; Lanphear et al., 2001). Approximately 30% of acute exacerbations of childhood asthma are environmentally related, and the environmentally attributable cost of all pediatrie asthma was estimated to be $2.0 billion annually in 2002 (Landrigan et al., 2002).
Ground-level ozone is the principle source of outdoor air pollution that triggers and exacerbates asthma (Friedman, Powell, Hutwagner, Graham, & Teague, 2001). Meeting the eight-hour ozone standard could have saved approximately $5.7 billion (averaged over three years, 2000-2002) in reduced health effects such as premature death, hospital admissions, asthma emergency department visits, school absences, and restricted activity days (Hubbell, Hallberg, McCubbin, & Post, 2005).
Chronic Obstructive Pulmonary Disease
Chronic obstructive pulmonary disease (COPD) that is attributable to the environment accounted for an estimated 238,400 DALYs annually in the U.S. in 2007 (WHO, 2007). COPD actually refers to two lung diseases, chronic bronchitis and emphysema, which are characterized by obstruction of airflow that interferes with normal breathing (American Lung Association [ALA], 2006). It is a slowly progressing disease that is characterized by a gradual loss of lung function.
In 2004, all COPD cases, environmentally induced and otherwise, cost the U.S. approximately $37.2 billion. This figure included direct health care expenditures of $20.9 billion, $7.4 billion in indirect morbidity costs, and $8.9 billion in indirect mortality costs (ALA, 2006). In developed nations, approximately 10%-30% of COPD cases can be attributed to the environment (Prüss-Üstün & Corvalán, 2006). If we assume this attributable fraction is accurate for the U.S., then the cost of COPD cases due to the environment is approximately $3.7-$11.2 billion.
Smoking is the greatest risk factor for COPD. Other environmental risk factors include air pollution, occupational exposure to dust and chemicals, and ETS (Prüss-Üstün & Corvalán, 2006).
Respiratory infections caused by the environment accounted for an estimated 59,600 DALYs annually in the U.S. in 2007 (WHO, 2007). These infections included pneumonia, common cold, and influenza. The cost to employers of patients with respiratory infections, environmentally caused and otherwise, was $112 billion in 1997. This included costs of medical treatment and time lost from work due to disability and medical treatment; however, it did not include time away from work due to sick leave (Birnbaum, Morley Greenberg, & Colice, 2002).
Indoor and outdoor air pollution, smoking, and ETS are environmental risk factors for respiratory infections. In developed countries, 20% of lower respiratory infections and 12% of upper respiratory infections are attributable to the environment (PrüssÜstün & Corvalán, 2006). If we assume 15% of respiratory infections are due to the environment, the environmental burden of respiratory infections would be $16.8 billion (in 1997 dollars).
The environmental burden of disease in the U.S. is very costly. It is estimated that 5,662,000 DALYs and 398,000 deaths annually can be attributed to the environment (WHO, 2007). Environmental interventions exist that can decrease the number of DALYs from which Americans suffer. Some of these include improving housing conditions by abating lead-based paint and interior moisture, which can decrease the burden of childhood lead poisoning and asthma (Jacobs, Wilson, Dixon, Smith, & Evens, 2009). The Centers for Disease Control and Prevention (CDC) recommend targeting lead poisoning-prevention efforts to communities and populations at highest risk for elevated blood lead levels (CDC, 2000). Smoking and tobacco-cessation programs and reducing exposure to ETS can decrease the burden of cardiovascular disease, cancer, asthma, COPD, and respiratory infections (ACS, 2008; Johnson, 2003).
Providing economic incentives, such as tax credits or subsidized transit passes, as well as modifications to the built environment can encourage people to use alternative transportation (bus, train, carpool, walk, bike, or drive low-emissions vehicles). These actions can facilitate more active lifestyles and improve air quality by reducing pollution from vehicles which, in turn, may reduce DALYS due to cardiovascular disease, cancer, asthma, COPD and respiratory infections (Frank & Engelke, 2005; Prüss-Üstün & Corvalán, 2006). Understanding the cost of environmentally caused diseases, then systematically identifying and evaluating the efficacy of interventions, can help us direct limited resources towards public health programs that will have the greatest impact.
This review was subject to several limitations. Due to the limited scope of the project, a literature review was conducted, as opposed to original economic analysis. A more in-depth study could be conducted using Medical Expenditure Panel Survey data to estimate the prevalence and dollar cost of each of these conditions. The etiology of many diseases is not completely known; therefore, it is difficult to predict which fraction of the incompletely understood causes are environmental. WHO consulted worldwide experts on each of the diseases and asked them to estimate the proportion of the disease that was attributable to the environment. Many of the studies available in the literature and referenced here provide the entire cost of a particular disease, but do not specify the proportion of the disease due to the environment. Other studies focus on a small geographical area and cannot be accurately extrapolated to the entire U.S. Methods vary substantially among studies, making it difficult to compare study results. Therefore, an original economic analysis examining the entire cost of disease attributable to the environment in the U.S. would be a useful addition to the literature.
Disclaimer: The findings and conclusions in this paper have not been formally disseminated by the Agency for Toxic Substances and Disease Registry and should not be construed to represent any agency determination or policy.
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Katherine H. Pugh, MS
Gregory M. Zarus, MS
Corresponding Author: Katherine Pugh, Environmental Health Scientist, Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy, NE, MS F-59, Atlanta, GA 30341. Email: firstname.lastname@example.org.