Study Methodology
This analysis estimates the costs for the following diseases: adult and childhood asthma, adult cardiovascular disease, adult and childhood cancer, childhood lead poisoning, birth defects, and childhood neurobehavioral disorders. For most of the analysis, we used Landrigan’s framework, but we have also incorporated updated methods from more recent studies, including Massey & Ackerman (2003) and Schuler et al. (2006).
Environmentally attributable fractions (EAFs): This study utilizes the same EAFs used in the 2002 Landrigan et al. study. While there is growing scientific evidence that exposure to environmental contaminants plays a role in many diseases and disabilities, the precise proportions attributable to environmental contaminants will probably never be known. To take account of this uncertainty, the environmentally attributable fractions (EAFs) used in this study are conservative and are expressed as ranges, or environmentally attributable fraction ranges (EAFR). For each cost calculation, we provide a best estimate of the costs for the proportion of disease and disability attributable to environmental contaminants. The best estimate uses the consensus EAF arrived at by the panel of experts in the Landrigan et al. study to determine the estimated costs. The EAFRs are utilized to reflect the range of uncertainty in the underlying assumptions and beliefs of the consensus panel. The reasoning for EAFR and the best estimate for each disease and disability is discussed in the relevant section below.
Definition of environmental factors: For the purposes of this study, environmental factors are defined as air, water and soil pollutants, both naturally occurring and anthropogenic. Examples include metals such as lead and mercury; chemicals such as benzene, acrolein, and dioxins; pesticides used both agriculturally and in residences; particulate matter (PM) from the combustion of fossil fuels; and other toxic substances to which people may be exposed. This definition is used because the exposures included within it are potentially preventable through application of pollution prevention and public health approaches. This definition of environmental factors does not include diet, smoking, alcohol consumption, sexual behavior, infectious disease, accidents or injuries.
National cost estimates: Where national cost estimates have been used, they have been converted to state estimates based on population data taken from the U.S. Census Bureau. According to the 2000 Census, the total U.S. population was 281,421,906 and the population of Oregon was 3,421,399 (U.S. Census Bureau, 2006). Based on these data, the population of Oregon is approximately 1.22% of the national total.
Disease incidence/prevalence and cost data: We utilized actual Oregon data on disease rates and costs whenever available. If state-specific data were not available, we extrapolated from national estimates, using census data to estimate the Oregon proportion of the U.S. population. This assumption does not take account of the possibility that the rates of disease and disability in Oregon may be different from national ones.
Data sources for each disease or disability are:
Asthma: Estimated total national costs, national cost-per-case data, Oregon-specific asthma prevalence, and Oregon-specific population <18 years of age.
Cardiovascular Disease: Estimated total national costs, Oregon-specific estimated costs, and Oregon-specific heart disease and stroke rates.
Cancer: National cost-per-case data, Oregon-specific cancer incidence, and estimated total national costs.
Lead Poisoning: National data on loss of lifetime earnings, national prevalence of lead poisoning, and Oregon-specific birth rates.
Birth Defects: National incidence and cost information, and Oregon-specific birth rates.
Neurobehavorial Disorders: National cost data, Oregon-specific costs for special education, and Oregon-specific data for the number of children enrolled in K-12 public schools.
Costs included: This study includes costs relating to both direct and indirect health care costs. Direct health care costs include inpatient, outpatient, and emergency room care, physician services, and medications. Indirect health care costs include lost work and school days, lost productivity due to premature death, loss of parental wages, and loss of future income due to loss of IQ. Not all of these costs were used in all estimates and for some disease categories additional costs were considered. The specific costs for each disease category are discussed in each relevant section.
Costs not included: This study does not include costs relating to legal and social services, childcare costs and lost productivity due to family illness and care. The lead exposure estimate does not take into account direct health care costs for screening and treatment, or indirect costs such as special education and juvenile justice services. We do not include the costs of a number of adverse social outcomes associated with lower IQs such as poverty, receiving welfare, dropping out of high school, low-weight birth complications, and involvement in the criminal justice system (Muir & Zegarac, 2001). These costs were excluded because of the limited amount of reliable or disease specific estimates associated with these costs.
Inflation factor: This study utilizes the Department of Labor’s Consumer Price Index Inflation Calculator to calculate cost estimates in 2007 dollars. The inflation factor can be found at: http://www.bls.gov/cpi/home.htm. This Inflation Calculator is a generic national inflation calculator, and it does not take account of the fact that the estimated costs in this study may have risen at a different rate than the national inflation rate. Additionally, it does not take into account that inflation in Oregon may have risen at a different rate than the national rate.
Complete details on the methods, assumptions and data sources used to derive cost estimates are described in the disease-specific sections that follow.
