Environmental Justice AnalysisTheories, Methods, and Practice - Chapter 4

4 Measuring Environmental and Human Impacts Executive Order 12898 orders each Federal agency to identify and address, as appropriate, disproportionately high and adverse human health or environmental effects of its programs, policies, and activities on minority populations and low-income populations. What are human health or environmental effects? The concept of environmental impacts has been broadened considerably over the past century. The initial focus is human health. From time immemorial, people rec-ognized that certain plants are toxic to human health. There are also natural hazards that are detrimental to human health and well-being. The modern industrial revolution not only led to prosperity and enhanced human capability to fight hazards but also generated a harmful by-product, environmental pollution. People realized that pollution could be deadly from the tragic episodes of air pollution in Donora, Pennsylvania in 1949 and in London, England in 1952. Carson’s Silent Spring raised the public’s awareness of environmental and ecological disasters caused by modern industrial and other human activities. Now, we know that environmental impacts can occur with respect to both the physical and psychological health of human beings, public welfare such as property and other economic damage, and ecological health of natural systems. In this chapter, we will examine how environmental impacts are measured, modeled, and assessed, and explore the possibility and difficulties of using a risk-based approach in environmental equity studies. First, we will review major types of environmental impacts, which include human health, psychological health, prop-erty and economic damage, and ecological health. Then we discuss approaches to measure, model, and simulate these impacts. We will discuss the strengths and weaknesses of these methods and their implications for equity analysis. Finally, we examine the critiques and responses of a risk-based approach to environmental justice analysis. 4.1 ENVIRONMENTAL AND HUMAN IMPACTS: CONCEPTS AND PROCESSES Environmental impacts occur through interaction between environmental hazards and human and ecological systems. Environmental hazard is “a chemical, biolog-ical, physical or radiological agent, situation or source that has the potential for deleterious effects to the environment and/or human health” (Council on Environ-mental Quality 1997:30). An environmental impact process is often characterized as a chain, including · Sources and generation of environmental hazards · Movement of environmental hazards in environmental media · Environmental exposure · Dose · Effects on human health and/or the environment Environmental hazards come from both natural systems and human activities. For example, toxics come from stationary sources such as fuel combustion and industrial processes, mobile sources such as car and trucks, and natural systems. Emission level is only one factor for determining eventual environmental impacts. Other factors include the location of emission, time and temporal patterns of emis-sion, the type of environmental media into which pollutants are discharged, and environmental conditions. After being emitted into the environment, pollutants move in the environment and undergo various forms of transformation and changes. The fate and transport of pollutants are affected by both the natural processes such as atmospheric disper-sion and diffusion and the nature and characteristics of pollutants. Some pollutants or stressors decay rapidly, while others are persistent and long-lived. Some environ-mental conditions are amenable to formation of pollution episodes, such as inversion layers in the Los Angeles Valley and high temperatures in the summer, which facilitate formation of smogs. When undergoing these fate and transport processes, pollutants reach ambient concentrations in environmental media, which may or may not be harmful to humans or the ecosystem. Research has investigated the level of ambient concentrations that impose adverse impacts on the environment and/or human health. These studies provide a scientific basis for governments to establish ambient standards for protecting humans and the environment. Ambient environmental concentrations of pollutants, no matter how high, will not impose any adverse impacts until they have contact with humans or other species in the ecosystem. Whether or where such contact with humans occurs depends on the location of human activities; it could happen indoors or outdoors. Indoor con-centrations could differ dramatically from outdoor concentrations. Environmental exposure is a “contact with a chemical (e.g., asbestos, radon), biological (e.g., Legionella), physical (e.g., noise), or radiological agent” (Council on Environmental Quality 1997:30). The Committee on Advances in Assessing Human Exposure to Airborne Pollutants of the National Research Council (1991:41) defines exposure as contact at a boundary between a human and the environment at a specific contaminant concentration for a specific interval of time; it is measured in units of concentration(s) multiplied by time (or time interval). In the real world, exposure happens daily and there are generally more than one agent and source. This is called multiple environmental exposure, which “means exposure to any combination of two or more chemical, biological, physical or radiological agents (or two or more agents from two or more of these categories) from single or multiple sources that have the potential for deleterious effects to the environment and/or human health” (Council on Environmental Quality 1997:30). Furthermore, environmental exposure occurs through various environmental media and accumulates over time. Cumulative environmental exposure “means exposure to one or more chemical, biological, physical, or radiological agents across environ-mental media (e.g., air, water, soil) from single or multiple sources, over time in one or more locations, that have the potential for deleterious effects to the environ-ment and/or human health” (Council on Environmental Quality 1997:30). Human exposure to environmental hazards can come from many contaminants (for example, heavy metals, volatile organic compounds, etc.) generated from many sources (such as industrial processes, mobile sources, and natural systems), from various environmental media (air, water, soil, and biota), and from many pathways (inhalation, ingestion, and dermal absorption). As a result of exposure to pollutants, humans receive a certain level of dose for those pollutants. “Dose is the amount of a contaminant that is absorbed or deposited in the body of an exposed organism for an increment of time” (National Research Council 1991:20). Dose can be detected from analysis of biological samples such as urine or blood samples. Human response may or may not occur with respect to a certain dose level. Different toxics have different dose-response relationships. The response to an expo-sure includes one of the following (Louvar and Louvar 1998): · No observable effect, which corresponds to a dose called no observable effect level (NOEL) · No observed adverse effect at a dose called NOAEL · Temporary and reversible effects at effective dose (ED), for example, eye irritation · Permanent injuries at toxic dose (TD) · Chronic functional impairment · Death at lethal dose Human health effects are often classified as cancer and non-cancer, with corre-sponding agents called carcinogens and non-carcinogens. Cancer endpoints include lung, colon, breast, pancreas, prostate, stomach, leukemia, and others. Non-cancer effects can be cardiovascular (e.g., increased rate of heart attacks), developmental (e.g., low birth weight), hematopoietic (e.g., decreased heme production), immuno-logical (e.g., increased infections), kidney (e.g., dysfunction), liver (e.g., hepatitis A), mutagenic (e.g., hereditary disorders), neurotoxic/behavioral (e.g., retardation), reproductive (e.g., increased spontaneous abortions), respiratory (e.g., bronchitis), and others (U.S. EPA 1987). Based on the weight of evidence, the EPA’s Guidelines for Carcinogenic Risk Assessment (U.S. EPA 1986) classified chemicals as Group A (known), B (probable), and C (possible) human carcinogens, Group D (not classified), and Group E (no evidence of carcinogenicity for humans). Known carcinogens have been demon-strated to cause cancer in humans; for example, benzene has been shown to cause leukemia in workers exposed over several years to certain amounts in their workplace air. Arsenic has been associated with lung cancer in workers at metal smelters. Probable and possible human carcinogens include chemicals for which laboratory animal testing indicates carcinogenic effects but little evidence exists that they cause cancer in people. The Proposed Guidelines for Carcinogenic Risk Assessment (U.S. EPA 1996a) simplified this classification into three categories: “known/likely,” “can-not be determined,” and “not likely.” Subdescriptors are used to further differentiate an agent’s carcinogenic potential. The narrative explains the nature of contributing information (animal, human, other), route of exposure (inhalation, oral digestion, dermal absorption), relative overall weight of evidence, and mode of action under-lying a recommended approach to dose response assessment. Weighing evidence of hazard emphasizes analysis of all biological information, including both tumor and non-tumor findings. Estimates of mortality and morbidity as a result of environmental exposure vary with studies. An early epidemiological study attributed about 2% of total cancer mortality in the U.S. to environmental pollution, 3% to geophysical factors such as natural radiation, 4% to occupational exposure, and less than 1% to consumer products (Doll and Peto 1981). Half of total pollution-associated cancer mortality was attributed to air pollution (4,000 deaths annually in 1981). U.S. EPA (1987) used risk assessment to estimate cancer incidences caused by most of 31 environ-mental problems. Transformation of cancer incidence into cancer mortality, using a 5-year cancer survival rate of 48% and an annual death toll of 485,000 from cancer, shows that EPA’s estimates are similar to Doll and Peto’s estimates (Gough 1989). EPA’s estimates translate to 1–3% of total cancer deaths that can be attributed to pollution and 3–6% to geographical factors. Recent studies show that occupational and environmental exposures account for 60,000 deaths per year (McGinnis and Foege 1993) and particulate air pollution alone could account for up to 60,000 deaths per year (Shprentz et al. 1996). The environment and ecosystem may respond differently to various chemical, physical, biological, or radiological agents or stressors. Some agents or stressors may pose risks to both humans and the environment, while others affect just one of them. For example, radon is a serious risk for human health but does not pose any ecological risk. Conversely, filling wetland may degrade terrestrial and aquatic habitats but does not have direct human health effects. Two commonly cited eco-logical effects are extinction of a species and destruction of a species’ habitat. Although impacts on humans often focus on the chemical agents or stressors, both physical and chemical stressors often have significantly adverse impacts on the ecosystem. For example, highway construction may cause habitat fragmentation and migration path blockage. Ecological impacts can be assessed according to criteria such as areas, severity, and reversibility of impact (U.S. EPA 1993a). In addition to health, impacts of environmental hazards on humans also include those on social and economic (sometimes referred to as quality of life) issues. Examples are impacts on aesthetics, sense of community, psychology, and economic well-being. Economic damages have been widely documented and typically include damages to materials, commercial harvest losses (such as agricultural, forest, and fishing and shellfishing), health care costs, recreational resources losses, aesthetic and visibility damages, property value losses, and remediation costs (U.S. EPA 1993a). Economic impacts, particularly those to property value, have been a major concern as a result of environmental pollution, risks, environmentally risky or nox-ious facilities. Property value studies widely document property value damages associated with air pollution or economic benefits associated with improving air quality. A meta-analysis of 167 hedonic property value models estimated in 37 studies conducted between 1967 and 1988 generated 86 estimates for the marginal willingness to pay (MWTP) for reducing total suspended particulates (TSP) (Smith and Huang 1995). The interquartile range for estimated MWTP values is between 0 and $98.52 (in 1982 to 1984 dollars) for a 1-unit reduction in TSP (in micrograms per cubic meter). The mean reported MWTP from these studies is $109.90, and the median is $22.40. Local market conditions and estimation methodology account for the wide variations. Studies also report negative impacts of noxious facilities on nearby property values, as will be discussed in detail later in the chapter. Social impacts have received increasing attention. Research has shown some psychological impacts associated with exposure to environmental hazards such as coping behaviors. Different environmental problems have adverse impacts on humans and the environment on different spatial scales. Some environmental hazards have adverse impacts in microenvironments such as homes, offices, cars, or transit vehicles. Examples include radon, lead paint, and indoor air pollution. Other environmental problems have global impacts such as global warming and stratospheric ozone depletion. Table 4.1 shows some examples of environmental problems and their spatial scales of impacts. It should be noted that some environmental problems can occur at different spatial scales. 4.2 MODELING AND SIMULATING ENVIRONMENTAL RISKS Environmental risks were often addressed on the basis of human health effects imposed by a single chemical, a single plant, or a single industry in a single environmental medium. Assessing the spatial distribution of environmental risks is TABLE 4.1 Spatial Scales for Various Environmental Problems Spatial Scale Examples of environmental hazards Home Indoor air pollution Radon Lead paint Domestic consumer products Community Noise Trash dumping Some locally unwanted land uses Hazardous and toxic waste sites Metropolitan Area Traffic congestion Ambient air pollution such as nitrogen oxides, VOCs, Ground-level ozone Region Tropospheric ozone Water pollution Watershed degradation Loss of wetlands, aquatic, and terrestrial habitats Continent/ Global Acid rain Global warming Stratospheric ozone depletion Source: U.S. EPA (1993a). ... - tailieumienphi.vn