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National Research Council (US) Committee on Health Impact Assessment. Improving Health in the United States: The Role of Health Impact Assessment. Washington (DC): National Academies Press (US); 2011.

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Improving Health in the United States: The Role of Health Impact Assessment.

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4Current Issues and Challenges in the Development and Practice of Health Impact Assessment

Chapter 2 discussed the need for health-informed decisions and the advantages of using health impact assessment (HIA) to evaluate the potential health consequences of an array of projects, plans, programs, and policies. Chapter 3 provided a framework for HIA and highlighted critical elements of each step in the HIA process. This chapter identifies and explores several topics considered by the committee to be the most salient issues or challenges for the successful emergence, development, and practice of HIA. First, the committee addresses how health should be defined for HIA and how its definition influences the application and scope of HIA practice. Types of decisions that are potential candidates for HIA are then considered. The committee next reviews several methodologic issues for HIA, including the need to balance timely information with variable data quality, expectations for quantitative estimates, synthesizing conclusions on dissimilar health effects, assigning monetary values to health outcomes, enabling stakeholder participation, and the benefits of a peer-review process for HIA. The committee then examines the potential for conflicts of interest among HIA practitioners, sponsors, and funders and considers whether it is realistic to expect the practice of HIA to result in a change in the decision being made. The committee concludes with a discussion of how HIA is related to the consideration of human health effects in environmental impact assessment (EIA) as required by the National Environmental Policy Act (NEPA) and similar state laws.


How health is defined and considered by society and government institutions— that is, what is or is not considered by practitioners, decision-makers, and stakeholders to have relevance to and a bearing on health—ultimately establishes the boundaries for HIA practice. That determination will clearly influence which decisions are considered appropriate subjects for HIA and which health effects are considered to be within its scope. Many have recognized that a narrow definition of health or factors that influence health probably limits the scope, application, and value of the practice.

The constitution of the World Health Organization (WHO) considers health broadly and states that “health is a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity” (WHO 1946, p. 100). Although there are many definitions of health—many less expansive than the WHO definition—there is a growing consensus that health at the individual and population levels is shaped by a combination of genetic, behavioral, social, economic, political, and environmental factors. As discussed in Chapter 2, the root causes or determinants of health include the quality and accessibility of infrastructure, such as housing, schools, parks, and transportation systems; the safety of the environment and economic security; the number and quality of social interactions; cultural characteristics, such as diet; and the level of equity and social inclusion. It is therefore essential that those many determinants be considered in defining the boundaries of HIAs. In the present committee’s view, HIA must be concerned broadly with individual and public health and all its social, cultural, political, economic, and environmental determinants.

Using such a broad definition of health has clear implications for which decisions may be subject to HIA, the scope of issues and measures used to characterize health in HIA, and how health effects are weighed in relation to competing outcomes. In general, the public-health practice has traditionally defined health more narrowly and focused on disease, morbidity, and longevity. Thus, many decisions that affect health determinants have been considered outside the scope and mandate of public-health institutions. As discussed in Chapter 2, the failure to attend to the broader health determinants—for example, economic conditions—have contributed to avoidable disease and health disparities (CSDH 2008). However, broadening the definition of health has implications for the work of other sectors and their relationships with each other and with public health. Expecting institutions outside the health-care and public-health sectors to advance public-health interests will be challenging because actions needed to protect and promote health are often in conflict with the interests and objectives of other sectors. Critics may question whether addressing public-health objectives should be weighed more heavily than meeting the objectives of the sector in whose domain a decision is being debated. Ultimately, broadening the definition of health creates the setting where tradeoffs among health and other social objectives can be made transparently. Recent calls for public agencies to consider and take actions to improve health indicate changing attitudes and the need to create a more multidisciplinary approach to public health (CSDH 2008). The committee supports the recent government actions and emphasizes the need to define health broadly in the practice of HIA but recognizes that implementation will require some care to balance health with the many other considerations that are important to any given decision.


A frequent question—given the breadth of potential applications of HIA— is whether there is a limit on the types of decisions to which the practice might be applied. For example, is HIA better suited to decisions in particular policy sectors (such as education, urban planning, and finance), to a particular scale (such as policy vs project) or jurisdictional level, or to particular health outcomes? The question is important because there are few formal requirements for analyzing the health effects of decisions except for the requirements for health analysis under NEPA and state environmental policy acts (SEPAs), and as demand for HIA grows, there will be a greater need to target its applications efficiently.

The broad definition of health discussed above suggests that a wide array of decisions—including some of those made in almost all government sectors on local, state, national, and international scales—may be appropriate candidates for HIA (Harris-Roxas and Harris 2011). A review of the sectors in which HIAs have been completed in the European Union (EU) (Wismar et al. 2007) and in the United States (Dannenberg et al. 2008; HIA-CLIC 2010; RWJF/PEW 2011) underscores this breadth of potential applications (see Table 4-1). Although most U.S. examples reflect applications in the transportation, housing, or urban-planning sectors, there is growing diversity in the United States and a wider diversity in the existing spectrum of EU applications. The growth may be because of greater experience with and public support for HIA and increased public recognition of the many determinants of health.

TABLE 4-1. Health Impact Assessment by Sector.


Health Impact Assessment by Sector.

In the committee’s view, restricting the spectrum of HIA practice to particular decisions, sectors, decision scales, jurisdictional levels, or health issues is unwarranted. At this early stage, there is no evidence to suggest that HIA is more important, appropriate, or effective in any particular decision context. On the contrary, HIA may be useful across a broad array of decision contexts, including many decision types to which it has not yet been applied. Furthermore, new global health challenges are likely to emerge from issues related to atmospheric and climate change, population growth, food and land scarcity, revolutionary industrial technologies (such as nanotechnology and gene modification), globalization, and economic inequities (WWF/ZSL/Global Footprint Network 2010). For example, a changing climate and an increase in extreme weather events will have many effects, including widespread effects on health (Costello et al. 2009; Luber and Prudent 2009). Public policy in general and public health and HIA in particular must recognize the emerging challenges and support the identification of adaptive and preventive strategies. HIA may play a substantive role in emphasizing the importance of the emerging issues to public health and to policy-makers and stakeholders.

Although most decisions have the potential to affect health, conducting HIAs of all decisions is clearly not practical or expected. Accordingly, HIA proponents should try to select decisions that have the greatest opportunities for advancing public-health goals and promoting the awareness of the health implications of decision-making. As described in Chapter 3, one purpose of the screening step in HIA is to focus HIA on high-priority topics by explicitly considering the value of conducting HIA in a particular situation. For example, findings of an HIA of a proposed decision may be appropriately applied to a similar decision in another context or on another scale (for example, regulations for labor standards on city, state, and federal scales), so the value of conducting another HIA may be diminished.

The committee emphasizes that as long as HIA is conducted as a voluntary process, it will be difficult to ensure that it is directed at the most important health priorities and decision opportunities. Aside from the limited analysis of health effects that is currently conducted within the regulatory structure of EIA, practitioners of or those funding or sponsoring HIA are in most cases selecting decisions by using ad hoc mechanisms based on their own interests and goals and are considering a limited set of candidate decisions (for example, land-use projects in a particular locality). Without clear mandates, screening criteria, and procedural rules for HIA, the selective approach to conducting an HIA may miss decisions for which HIA would have value and produce some HIAs that have little utility for decision-makers or stakeholders. 1 Furthermore, HIA could conceivably contribute to health inequities if more socioeconomically or politically advantaged communities develop greater capacity to demand HIA or if health issues that are highlighted in HIA are focused on the health needs of the advantaged.

In contrast, institutional rules for HIA—for example, rules articulated in laws at the local, state, or federal level—could establish consistent procedures for the field and ensure that a sufficiently broad set of candidate decisions are screened. For example, decisions subject to HIA might be selected and ranked on the basis of the likelihood of addressing the Healthy People 2020 objectives of the U.S. Department of Health and Human Services or on the basis of the most realistic opportunities to address environmental injustice or to reduce health inequities. Institutional rules could effectively narrow a large number of candidate decisions to a manageable ordered set, enhance the use of HIA, and advance its rationale and equitable use. Such rules could also help to organize and direct the creation of a coherent and systematic body of knowledge about decision-related health effects and analytic methods that could be used for HIA. Thus, the committee finds that any future policies, standards, or regulations for HIA should include explicit criteria for identifying and screening candidate decisions and rules for providing oversight for the HIA process; such criteria and rules would promote the utility, validity, and sustainability of HIA practice.


A substantial challenge facing HIA practitioners is the quality and availability of evidence on which to base predictions about health effects (Mindell et al. 2004; Petticrew 2007; Veerman et al. 2007; Bhatia and Seto 2011; Mindell et al. 2010). More broadly, scholars acknowledge that the studies and empirical evidence linking improvements in health directly to changes in specific public policies are sparse (Curtis et al. 2002; Dow et al. 2010; Graham 2010). Furthermore, many decisions occurring outside the health sector have not previously been seen as important for health, so they have typically not been the subject of rigorous empirical health research. Thus, making prospective judgments about the effects of policy decisions on health is challenging, and concerns about validity arise in the face of variable and often sparse evidence.

The committee emphasizes that concerns about validity must be balanced against the reality that decisions that are not informed by health analysis have the potential to harm health (see Chapter 2); this implies that the degree to which the evidence limits judgments must always be weighed against the potential severity and scope of harm that could occur if available information were not considered. But practitioners should also consider the risk, both to optimal decision-making and to the legitimacy of the field, that is inherent in overstating the precision or certainty of health-effect estimates provided by HIA.

There are challenges to addressing concerns about the validity of HIA predictions. Regardless of evidence-related constraints, HIA must operate in the context of practical realities and timelines of the decision-making process, and HIA reports need to express clearly the quality of evidence and the degree of confidence in inferences drawn from the evidence. The committee notes that society regularly accepts such practical limitations in making policy decisions and that predictive certainty or causal certainty would be an impractical standard for HIA.

Practical and agreed-on methods for addressing concerns about validity are needed, and the committee offers three strategies, discussed below, that should help to improve the validity of health-effects judgments made in the context of variable evidence:

  • Consider diverse evidence sources by using expertise in multiple disciplines.
  • Assess the quality of available evidence.
  • Include a strategy for assessing and managing uncertainty.

HIA practitioners can also learn from the health-risk-assessment field where some analysts have demonstrated the ability to adapt their analyses to varied evidence, ranging from data extrapolated from the literature when local information is lacking to primary reliance on local data that leverage knowledge and statistical power from the broader literature (Hubbell et al. 2009).

Consider Diverse Evidence Sources by Using Expertise in Multiple Disciplines

As discussed in Chapter 3, many types of evidence can be used in HIA, including peer-reviewed academic studies; unpublished, publicly available studies and databases, that is, gray literature; survey, monitoring, or interview data specific to the affected population or to the policy, plan, program, or project in question; the experience of people who will be affected by the proposed changes; and expert opinion. The committee recommends that practitioners review all the available evidence systematically (Mindell et al. 2010). Practitioners should use published, peer-reviewed systematic reviews—such as those conducted by the Cochrane Collaboration, WHO, the U.S. Environmental Protection Agency, and other authoritative bodies—if they are available. Although studies conducted within the population that might be affected are ideal, they may not exist or be feasible to conduct, so analysis will turn to literature and data on other populations.

HIA is necessarily a multidisciplinary practice. It is often, although not exclusively, carried out by public-health professionals, but it almost always requires access to experts in the core domains that are affected by the proposal under consideration. Multiple disciplines will help to reveal differences of opinion, will provide the team with access to a variety of evidence and analytic methods, and may provide a more robust critique of methods, findings, and conclusions. The participation of multiple public agencies—such as health, planning, and transportation agencies—not only will contribute expertise but may ensure that the process addresses questions pertinent to the decision at hand and thus increase the likelihood that the recommendations are actionable and will be adopted. Furthermore, conducting HIA as a multidisciplinary practice can assist in developing ownership and commitment for health goals among multiple institutional and disciplinary sectors. The committee nevertheless recognizes that it can be challenging to conduct multidisciplinary analysis or to manage the participation of multiple agencies or participants.

In selecting evidence and evaluating quality, practitioners should recognize their own biases and the biases of decision-makers, project proponents, or HIA sponsors. Biases may affect the value attached to particular types of evidence. For example, evidence from consultation, which can be more readily dismissed as hearsay or anecdotal, may not be accorded as much weight as the quantitative modeling of environmental exposure or economic effects (Ozonoff 1994). Other biases related to conflicts of interest are discussed later in this chapter.

Evaluate Evidence Quality

HIA practitioners should select the strongest evidence and analytic methods that are available for a particular decision context. For transparency, it is equally important to state the rationale for choosing particular evidence or methods when alternatives are available. Key factors that should be considered in determining whether to use a given study or dataset include the relationship between study end points and the issues evaluated in the HIA, the quality of the data and their statistical power, the adequate assessment of factors that could impede causal inference (that is, the internal validity of an empirical study) (Susser 1986; Rothman and Greenland 1998; Weed 2005), and the applicability of the evidence to the target population (that is, external validity). The quality of evidence used in HIA may also be assessed according to the core standards of the discipline in which the data originate; for example, epidemiologic studies should generally be evaluated according to quality standards for epidemiologic studies with attention to such issues as the potential for bias and confounding.

There are no uniform standards for evaluating all potential evidence that might be used in HIA given the diversity of applications and of the evidence base. However, many of Bradford Hill’s (Hill 1965) causal criteria—such as strength of association, consistency of evidence among studies and data sources, coherence with known facts of the exposure and disease, and analogy to similar situations—could be applied to HIA when evaluating the likelihood of health effects. Other criteria could be developed to extrapolate findings on study populations to the target populations for specific decisions. And criteria could be developed in ways that are specific to the needs of different policy contexts.

Setting any uniform evidence standards carries some risk of limiting the scope of health effects and pathways assessed in HIA. In health risk assessment, even with assumptions and acceptance of uncertainty, evidence requirements in practice have constrained analysis to a limited set of exposures and outcomes (NRC 2009). Even if HIA practice evolves standardized approaches for the analysis of particular decisions, determinants, or health effects, there will be a need for flexibility to address new and emerging issues.

Characterize and Manage Uncertainty

Uncertainty will always be present, and impact assessments—including HIAs—should characterize and manage the uncertainty to the extent possible and practicable that is inherent in the analyses and decisions. Although uncertainty should not be ignored in HIA, it should also not paralyze the decision process. Furthermore, there may be situations in which the magnitude of uncertainty is large enough to make selection among competing alternatives challenging, but the potential impact may be important enough to justify intervention in the face of that uncertainty.

Managing uncertainty in HIA can include planning how the analysis will address uncertainties and establishing procedures to characterize or reduce key uncertainties. Uncertainty in the analysis of health effects can be characterized in a variety of ways, ranging from qualitative descriptions to quantitative analysis. Quantitative analyses of uncertainty are common in related fields, such as health risk assessment, and are relevant if the key health effects are quantified in the HIA. Distributions of estimates based on various assumptions have been presented in HIA (Schram-Bijkerk et al. 2009), but it typically includes only a subset of assumptions for which distributions can be readily quantified and omits some major sources of uncertainty for which quantification is impractical. More generally, although formal propagation and quantification of uncertainty can be helpful in elucidating the influence of key assumptions, they contribute to a lack of methodologic transparency for many stakeholders and raise potential issues with timeliness. At a minimum, uncertainties in assumptions used to support health-effect characterization should be described qualitatively. In other words, HIA practitioners should evaluate and document the uncertainty of their conclusions by describing the evidence on which their conclusions are based and by identifying any limitations, gaps, or weaknesses in the assumptions. That exercise should go beyond parametric uncertainty described in individual studies to consider broader questions, such as whether a measure of exposure used in HIA was a reliable proxy for personal exposure or whether an exposure-response function extracted from the literature can be generalized to the population of interest.

Similar issues have been confronted in the domain of health risk assessment. The National Research Council report Science and Decisions: Advancing Risk Assessment (NRC 2009) concluded that the plans for uncertainty analysis should be discussed during the scoping process to ensure that the information generated meets the needs of decision-makers and to avoid unnecessarily complex (and untimely) uncertainty analyses. For example, if a mitigation or alternative is readily available and affordable for managing a health impact of concern and has greater benefits than other alternatives, a formal treatment of uncertainty may be unnecessary. Planning of how uncertainty will be evaluated and managed— including quantitative and qualitative elements—should be a component of the scoping process of HIA (see Chapter 3). The plan should consider how stakeholders may wish to see uncertainty information presented, including the method of presentation and the emphasis on distributions vs expected values vs upper or lower bound values for aspects that can be quantified. Various approaches for characterizing the sophistication of uncertainty analysis (Pate-Cornell 1996; IPCS 2006) could be adapted for HIA, as could previously recommended strategies for addressing and communicating uncertainty in complex multifactorial models (NRC 2007) and in cost-effectiveness analysis (Briggs 2000; Claxton 2008).

As suggested, characterization of uncertainty will often need to go beyond quantitative methods to include other forms of information. Using a deliberative group process to arrive at judgments is a nonquantitative way to manage uncertainty and to moderate the effects of individual and organizational values and biases. HIA conducted as a deliberative group process that involves open discussion and debate among the stakeholders may also be useful in generating judgments that will be widely accepted. The National Institutes of Health uses a deliberative process to achieve consensus on many clinical issues in medicine (NIH 2011); this approach may have value in managing uncertainties in HIA.

As the practice of HIA evolves, there may be uncertainties and data limitations that call for a set of practical assumptions to avoid subjective or ad hoc variations in analyses. In the practice of health risk assessment, default science-policy assumptions are used to allow the analysis to proceed with incomplete information (NRC 1983). For example, carcinogens whose mode of action is unknown are generally assumed to have linear dose-response functions at low doses, whereas nonlinear dose-response functions are assumed for noncancer health effects in the absence of specific evidence about mode of action or chemical pharmacodynamics. Similarly, when exposure or dose information is lacking, numerous default assumptions are used to capture breathing rates, drinking-water consumption, and various other behaviors or activities. In each case, there is inadequate information on the specific pollutants and settings of interest, but the analysis proceeds with assumptions derived from a combination of evidence from analogous situations and science-policy judgments. Although the variety of applications of HIA makes specific default science-policy assumptions difficult to formalize, the concept can be used to provide more transparency and interpretability. Over time, for policy contexts in which numerous HIAs are conducted, default science-policy assumptions could be generated and could facilitate comparability among HIAs. Regardless, HIA practitioners should explicitly describe where key judgments or assumptions were made, whether or not uncertainty can be formally characterized, and what implications the assumptions have on the HIA recommendations. In that way, the ultimate choice among competing options can be made by decision-makers given their preferences regarding action in the face of uncertainty.


Some decision-makers and HIA users expect HIA to provide quantitative estimates of health effects. Quantitative estimates of health effects have a number of desirable properties: they provide an indication of the magnitude of health effects, they can be easily compared with existing numerical criteria or thresholds that define the significance of particular effects, they allow one to make more direct comparisons among alternatives, and they provide inputs for economic valuation (see section “Assigning Monetary Values to Health Consequences” below). They can be produced when there has been sufficient empirical research on relationships between particular determinants and health outcomes. Accordingly, quantification is most feasible if a causal relationship can be inferred and if there is an externally valid effect measure or a defined exposure- response relationship (Hertz-Picciotto 1995; Fehr 1999; Mindell et al. 2001; O’Connell and Hurley 2009; Bhatia and Seto 2011). If information is lacking or uncertain, quantification may still be possible with the use of assumptions and inferences based on information drawn from analogous situations. In other situations, such as when assumptions are not defensible, quantitative estimates should not be advanced.

HIAs have applied quantitative techniques to decisions to estimate health effects related to expected changes in infectious-disease risks, traffic hazards, environmental pollutants, housing conditions, and tobacco and alcohol consumption (see Box 3-4; Veerman et al. 2005; O’Connell and Hurley 2009; Bhatia and Seto 2011). For example, quantitative impact-assessment methods have been used to estimate human health externalities associated with different fuels in Europe; the analysis was used to inform member states about the impacts of various fuels for electricity (such as nuclear fuel, coal, and natural gas) and was considered in numerous policy analyses, including strategies for internalizing external costs and development of sustainable-transport policies (O’Connell and Hurley 2009). Noise exposures and particulate-matter concentrations were modeled and associated with sleep disturbance and premature mortality, respectively, in local-scale assessments of residential development in San Francisco and waterfront development in Oakland; the assessments used quantitative exposure-response functions from the epidemiologic literature (Bhatia and Seto 2011). The effects of rezoning in San Francisco on pedestrian injuries were modeled on the basis of multivariate regression models derived from geocoded accident data and site characteristics, and changes in body-mass index and accident risks associated with increased walking of children to school in Sacramento were estimated by using data derived from epidemiologic investigations (Bhatia and Seto 2011).

Regardless of the advantages, relying exclusively on quantitative estimation in HIA presents some drawbacks. First, quantification has high information requirements. Given the breadth of health effects potentially considered in HIA, the sparse data available to support quantitative approaches, and the variability in practitioner capacity, it would be challenging if not impossible to expect all HIAs to predict all potentially important health effects quantitatively. Thus, an HIA that presents only quantifiable results would present only a partial accounting of health effects if not all important effects are amenable to quantification (Veerman et al. 2005; O’Connell and Hurley 2009). Second, because quantification can be resource-intensive, it may require more time than allowed for the evaluation of a policy, plan, program, or project. Third, a quantitative approach has implications for communicating the process and results to a wider audience because the methods are typically highly technical and include assumptions that may be difficult to communicate outside the technical team. Quantitative estimates may create an unwarranted impression of objectivity, precision, and importance and lead a reader to place importance or credence in quantified results even if assumptions and measures used in the analysis are based on subjective choices (O’Connell and Hurley 2009). Stakeholders, including lay audiences, may lose trust in the process, especially if they suspect that assumptions in calculations are influenced by the biases of those conducting or sponsoring the assessments (Ozonoff 1994; NRC 2009; O’Connell and Hurley 2009).

Overall, quantitative estimates of health effects have value and should be provided when the data and resources allow and when they are responsive to decision-makers’ and stakeholders’ information needs. This statement, however, should not imply exclusion of health effects from the analysis for which causal linkages have been made but quantification is impractical. Part of the scoping phase of HIA discussed in Chapter 3 should involve explicit consideration of which exposures and outcomes, if any, would be amenable to quantification and whether such analysis is feasible within the decision timeframe. To manage some of the challenges related to communication outlined above, the technical procedures and assumptions in quantitative analysis should be articulated clearly and explicitly. Approaches to characterize quantitative or technical information and communicate it to decision-makers have been described in detail elsewhere (see, for example, NRC 1989, 1996).


An HIA analyzes and reports findings on multiple health effects, so providing a simple conclusion is challenging. For example, an HIA conducted on a decision of whether to build a new rail line might evaluate its effects on sleep, asthma symptoms, and traffic injuries. In most cases, those health effects will be described with different units and measures and thus cannot be summarized by using the same unit of measurement; that is, it is not possible simply to add findings expressed in different health metrics. An important challenge is to synthesize and present results on dissimilar health effects in a manner that is intelligible and useful to stakeholders and decision-makers.

The most common approach in HIA is to describe and characterize each effect separately (see Chapter 3) and allow users to make judgments about the cumulative nature of the effects. The committee endorses that approach even if a summary measure of effects is used. Generally, decision-makers must balance multiple desirable and adverse effects related to a decision and will need to “weight” or assign values to them on the basis of institutional rules, constituent preferences, or some other approach. Keeping effects separate and assigning values allow decision-makers to consider tradeoffs among health and nonhealth effects clearly. As described in Improving Risk Communication, “reducing different kinds of hazard to a common metric (such as number of fatalities per year) and presenting comparisons only on that metric have great potential to produce misunderstanding and conflict and to engender mistrust of expertise” (NRC 1989, p. 52). The committee emphasizes the importance of characterizing adverse and beneficial effects separately in considering health disparities that could result from a decision; the distributional effects could be hidden or disappear if all effects are combined into one measure.2

As indicated above, an alternative way to present findings is to use a summary measure to translate estimated effects on disparate health end points into a single comparable unit, such as quality-adjusted life years (QALYs) (Hammit 2002), disability-adjusted life years, and healthy-years equivalent. Such health utility measures allow for disparate health outcomes to be weighted and combined, and they can include outcomes that are important for public health but are often omitted or underemphasized in health risk assessments (for example, mental illness). The health utility measures, however, bring assumptions that need to be recognized; for example, QALYs focus on years of remaining life expectancy and thus place greater weight on the life and well-being of a child than that of an elderly person. The committee recommends the consideration and application of summary measures in contexts where quantification is possible and the outcomes are amenable to assignment of quality weights or disability weights. However, as stated above, each health outcome should also be individually reported, and multiple summary measures should be used, when it is practical, to determine whether decisions are robust to the weighting scheme and to societal preferences among outcomes and populations.


The health consequences of a decision can be characterized according to their economic or monetary valuation. Although monetary effects clearly are not health effects themselves, many decision-makers and stakeholders may give substantial consideration to the economic value of effects, and economic valuation of health effects can facilitate comparison with the costs and benefits of competing alternatives (Brodin and Hodge 2008).

Economic valuation has several constraints and is not appropriate in all circumstances. First, the wide array of end points may not be amenable to monetary valuation. Second, monetary valuation of health outcomes has implicit and explicit weighting of outcomes and populations that may or may not reflect the values and priorities of decision-makers. For example, willingness to pay will tend to be greater among populations that have greater wealth and will tend to be lower among those who are facing competing risks (Hammitt 2002). Third, some populations may bear a disproportionate share of the health costs of a decision, and others a disproportionate share of the health gain. Those distributional effects can be hidden in cost-benefit analysis conducted at a societal level but would be potentially valuable information for those who incur the costs and for those who receive the benefits. Fourth, monetary valuation of health outcomes can pose a substantial communication challenge for affected parties and other stakeholders and may distract from the findings of an HIA. In spite of those caveats, monetary valuation of health outcomes may be a useful approach in some decision contexts, such as those in which alternative decision choices might require implementing economically costly mitigations.

If economic analysis is conducted as part of HIA, it is important to maintain the distinction between HIA, which provides judgments of health effects, and cost-benefit analysis, which provides a more comprehensive analysis of all economic benefits and costs of a decision. Economic valuation of health effects is common in existing cost-benefit analyses of federal regulations; however, HIA should not be characterized as or confused with cost-benefit analysis.


Chapter 3 emphasizes the importance of stakeholder engagement and participation in HIA and echoes the guidance provided repeatedly in the context of environmental risk assessment and risk management (PCCRARM 1997; NRC 2009). Individuals and organizations that are not part of the technical assessment team have the potential to make valuable contributions at each stage of the HIA process. Information gained through stakeholder involvement helps to illuminate important issues and focus the scope of an HIA on the most important or contested issues (Corburn and Bhatia 2007; Farhang et al. 2008; Corburn 2009). It can improve the quality and specificity of an analysis by, for example, highlighting local living conditions, prevalent health issues, and potential effects that might not be visible to practitioners from outside the community (Elliot and Williams 2004; Parry and Kemm 2005). Stakeholder involvement contributes to a more democratic planning or decision-making process by providing a structured and effective way for knowledge to be exchanged among those involved in planning and designing a proposal, those responsible for a decision, and those likely to be affected by the decision. It also helps to ensure that various stakeholder concerns receive adequate attention and that HIA recommendations are realistic and practicable.

The importance of including different perspectives and worldviews is highlighted by the experience of indigenous people whose perspectives and ways of thinking have often challenged knowledge used in, values underpinning, and processes for decision-making. The environment is of paramount importance to indigenous communities because many rely heavily on the land and natural resources for their subsistence, including their socioeconomic, cultural, spiritual, and physical survival (Kwiatkowski et al. 2009). For many indigenous groups, the “term environment does not distinguish between humanity and everything else; humans are part of the environment as much as the fish, wildlife, air, and trees” are (Kwiatkowski 2011, p. 447). Furthermore, the timeframe for EIA is typically shorter than that used when elders assess issues that face their communities (Williams 2010). For example, the constitution of the Iroquois Nations stipulates a period of seven generations over which to consider implications of any actions (Murphy 2001; Haudenosaunee Confederacy 2010). The knowledge and worldviews of indigenous people provide important insights that would not be known to people outside the community and illustrate why it is so important to provide opportunities for local input and influence and not to assume that all groups have a similar perspective.

Ensuring that stakeholders, including the public, are able to participate effectively in HIA is described in Chapter 3 as an essential element of practice (WHO 1999; Parry and Kemm 2005; IFC 2006; Quigley et al. 2006; Fredsgaard et al. 2009; Bhatia et al. 2010). But how or indeed whether practitioners enable stakeholders to participate in HIA varies widely (Kearney 2004; Mindell et al. 2004; Mahoney et al. 2007; Dannenberg et al. 2008). The variation may be attributable to the time and resources available for the HIA, to how high a priority HIA practitioners or sponsors give to participation, to a concern that participation may interfere with or impede progress toward the sponsors’ objectives, or to differences in the type and scale of the decision to which the HIA is to be applied (for example, local vs national level). However, it must be recognized that achieving representative participation is challenging, requires experience and particular skills, and may take different forms.

The decision context and the objectives of an HIA will influence who should be engaged, the challenges and opportunities for engaging key stakeholders, and the final selection of specific approaches to engage various stakeholders. For example, project-related decisions that will have direct and immediate implications for local neighborhoods should engage stakeholders from those communities. In contrast, national legislative decisions are more likely to involve representatives of interest-based or constituency-based organizations or possibly elected officials of constituencies that will be affected by legislation. Going beyond broad representative participation may not be necessary or feasible for an HIA of a national policy.

Techniques for stakeholder engagement and involvement are many and varied and can be chosen to suit a specific decision but need to address the barriers and challenges identified for each stakeholder group. Although open community meetings are likely to lend themselves to projects at a local level, other techniques (such as focus groups) can be adapted for any level by ensuring that they include key stakeholder communities and organizations that represent the groups most likely to be affected. Other approaches include interactive Web-based communications that facilitate effective exchanges among practitioners, sponsors, stakeholders, and the public and provide opportunities for stakeholders to review and comment on scope, data sources, findings, and recommendations (UNECE/REC 2007). Stakeholder engagement strategies that solicit and respond to comments on HIA reports only after they have been completed are restricted in their ability to take into account stakeholder concerns in the analysis and are typically viewed as reactive by stakeholders and the public. Whenever it is possible, strategies for stakeholder participation should extend beyond that minimal standard.

Formal oversight or advisory groups can be effective for continuing involvement, such as steering committees that are comprised of practitioners and stakeholders and provide oversight or direction and technical advisory committees that extend the expertise or range of disciplines brought to the HIA (Corburn and Bhatia 2007; Farhang et al. 2008). Formal collaboration agreements can also be used to define the roles and expectations of practitioners and stakeholders. In creating and working with groups, efforts must be made to ensure that members are representative, that differences in technical knowledge or power do not exclude members from full participation, and that disagreements among members are managed effectively. Conducting an HIA on local and regional policies, programs, or projects with the assistance of local community-based organizations that have deep local knowledge and networks is an effective way to achieve involvement of community members that have historically been excluded from decision-making (Wier et al. 2009).

Effective stakeholder participation potentially faces a number of challenges; as noted earlier, these are likely to depend on the scale of the decision for which HIA is being conducted. Participatory processes can favor those who have more resources and expertise and exclude local community or lay stakeholders. For example, groups that have fewer social and economic resources may be the least likely to participate. An equitable HIA process depends on strong efforts to identify and minimize barriers to participation and to ensure adequate representation for those unable to participate directly, for example, through elected officials in the case of national decisions. For HIAs of local and regional decisions, factors that can inhibit or prevent participation by individuals or groups that may be affected by the decisions vary—for example, structural issues, such as limited collective organization or lack of trust in public processes; poor access to elected decision-makers; and practical considerations, such as language or literacy barriers and the requirement to manage competing life needs. Similarly, for HIAs of national decisions (in which stakeholders may include constituency or interest groups or elected officials), people who are economically, socially, or linguistically marginalized may encounter particular challenges to full participation or representation. Efforts to address the challenges can include various strategies and again depend on the scale of the decision. For local or regional decisions, engagement of diverse stakeholders may include hosting meetings at venues in the community, providing translation and child care, scheduling interactions around work demands and important cultural events, and identification of formal and informal leaders in the community for continuing participation. For national decisions, efforts to ensure engagement of a broad array of stakeholders may include identification of regional or national interest groups that represent those likely to be affected by the decision and elected representatives from districts or regions likely to be affected by a decision. External facilitation of stakeholder engagement and involvement may be an effective option in some cases.


An important quality-control mechanism in the research process is peer review of the research plan or strategy and of the report that describes the analysis and results. Independent peer review provides a measure of credibility and legitimacy of findings and is commonly used in applied scientific disciplines to monitor practitioner conformity with established practices. HIA is different from primary scientific research in that it involves the application and interpretation of evidence in a particular decision context. Although premises underlying HIA judgments are often based on peer-reviewed evidence, several additional aspects of the HIA process might benefit from peer review.

HIA involves the selective identification of issues and the selective use of evidence. Peer review might identify overlooked issues or indicate opportunities to improve data or methods. Judgments about health effects are inferences based on evidence and observations that use reasoning and assumptions. Many of the procedural aspects of HIA—such as selection of evidence and transparency in the reporting stage of HIA—are instrumental in the acceptability and utility of findings in the decision process and may benefit from review by HIA experts who are independent of the process. Thus, peer review might increase the legitimacy of conclusions and their acceptance and utility in the decision-making process.

Regardless of the potential benefits, an accepted peer-review process for HIA would need to overcome several challenges. There are many stages at which peer review could theoretically be applied, and the multidisciplinary nature of HIA requires varied expertise and raises the issue of which people or teams would be best suited to conduct such a review. The involvement of teams of reviewers at multiple steps in the process could substantially increase the time and effort required to complete an HIA and could therefore make it less practical for decisions that need to be made in the short-term and for HIA teams with few resources. Peer review would also require agreed-on criteria, and at present there are no uniformly accepted criteria with which to judge the quality of an HIA. Furthermore, given the need for a flexible and adaptive tool that is applicable to an array of decision contexts, flexibility of quality criteria may be needed. In addition, peer review would need to be distinguished from public comment, and a process would need to be created to demonstrate responsiveness to peer-review comments.

Currently, peer review appears to be undertaken only intermittently, and the committee notes that the benefits of peer review need to be weighed carefully against the risk of delays that would render the HIA less relevant to the decision that it is intended to inform and the added costs and time that could restrict the use of HIA in some cases. Given the potential benefits, however, a formal peer-review process could be used at least in targeted large-scale, high-profile cases in which the benefits of added scrutiny and rigor would outweigh the disadvantages of added delay and process. In other cases, practitioners could consider a less structured process. For example, practitioners could request informally that colleagues review their HIAs or that they review particularly challenging, complex, or controversial aspects of their findings. It is common for HIA practitioners to get advice from other practitioners during the course of an HIA, and some implement technical advisory committees. Those approaches might achieve some of the objectives of an independent formal peer review. Development of accepted standards, databases, models, and default assumptions in the field would enable HIAs to be peer-reviewed with a consistent approach (Fredsgaard et al. 2009; Bhatia et al. 2009, 2010).


Impact assessments, including HIA, are conducted on decision proposals that are often contested among polarized and disparate interests and stakeholders. Regulatory assessment practices have been criticized as selectively representing interests, particularly those of development-project proponents. Given the decision-driven nature of HIA, even when there are substantial resources and high-quality data, results of HIA may still be contested and be subject to accusations of bias (Milner et al. 2003). Ensuring that the process by which HIA is conducted and the conclusions and recommendations that are produced at the end of the process are impartial, credible, and scientifically valid is paramount to the effectiveness of the practice (Veerman et al. 2006). To the extent feasible, those who conduct the assessment should strive to avoid real and perceived conflicts of interests.

The source of HIA funding is a common challenge to objectivity in HIA. Bias toward a funder’s interests is a well-recognized problem in many other forms of analysis and assessment. For example, Lexchin et al. (2003) found that results were more likely to favor pharmaceutical companies when they sponsored studies than when others sponsored them. In the practice of EIA, in which assessments of economic-development proposals are commonly funded and conducted by development proponents, assessors may feel substantial pressure to hide or minimize adverse effects of the proposals or to emphasize favorable effects (Morgan 1998). That bias can be reflected in issues and alternatives evaluated, methods used, assumptions made, results presented, and mitigations offered. An HIA funded by a development proponent may be similarly vulnerable to influence and may lead to a process that is more likely to find a result consistent with the interests of the sponsor.

Private commercial interests are not the only entities that may exert influence on HIA via funding or sponsorship. Private grant-makers (such as philanthropies) currently provide a substantial share of the funding for HIA that is conducted voluntarily in the United States. Philanthropies may influence the process or findings of HIA in several ways, for example, by directing HIA funding to assess specific health issues (such as air pollution or obesity), and this could potentially bias the scope of the assessment and the associated results. Mission-driven grant-makers may have strong expectations that HIA will produce substantive change in the issues and interests that they champion, or they may wish to see clear evidence that the HIA influenced a decision.

Government agencies sponsoring HIAs may also have interests that exert influence on HIA practices or conclusions. For example, government agencies may be less welcoming of results that potentially raise criticisms of their actions, identify their oversights, or challenge their positions. Like development-project proponents, public agencies may have a preferred decision outcome and may be interested in ensuring that HIA reflects favorably on that alternative. Such conflicts may be heightened if the agency conducting the HIA is also the responsible decision-maker.

In some cases, stakeholders or practitioners may decide to champion, sponsor, or conduct an HIA because of a strong interest in a specific decision outcome. They may seek to use HIA as a means to support or advocate for a particular policy outcome (Harris-Roxas and Harris 2011). In such cases, there may be a substantial risk of introducing bias into the HIA process.

The committee emphasizes that a lack of trust by any stakeholders in the HIA practitioner can undermine the legitimacy and influence of HIA. Therefore, it is important to guard against and mitigate the conflicts of interest described above. It may be useful for future practice guidance to establish a clear line between a practitioner’s role in conducting HIA and later efforts toward advocacy of particular decision outcomes.3 Although public entities may be somewhat less vulnerable to influence because of public funding sources, oversight mechanisms, and requirements for transparency, they are not immune to influence. Public-health agencies that have the necessary experience and expertise and the confidence of stakeholders may be in good positions to conduct or coordinate HIA given their mandate to protect public health. Other mechanisms to manage or mitigate influence may include the eventual creation of a dedicated public funding source to conduct HIA and a process of independent peer review of HIA as discussed above.


HIA clearly is intended to inform decisions, but information alone does not necessarily change decisions. The committee recognizes that the underlying motivation of HIA is to make policy and decisions that are more cognizant of and aligned with the interests of public health. Informing decision-makers can certainly influence attitudes and preferences and lead to more responsive health-supporting actions, but it is not reasonable to base the effectiveness of HIA on whether it changes decisions in which health is only one of many considerations and over which the HIA team lacks decision-making authority. Furthermore, support and legitimacy of the practice may be compromised if an HIA is conducted explicitly as a mechanism for decision advocacy.

It is reasonable to hope that identifying valid information about the health-related harms or benefits of a decision will motivate decision-makers to take protective actions. 4 However, generating high-quality health information and effectively communicating it does not ensure that the information is given high priority in the decision-making process or triggers action. HIA is not designed or practiced as a mechanism to regulate decision-making directly (that is, to require responsive actions if impacts exceed criteria). Although effective communication can raise awareness of and attention to health concerns, improved knowledge alone cannot necessarily change the ideology, interests, and attitudes of decision-makers. Health is typically one of many objectives under consideration in a given policy question, and decision-makers and other stakeholders are reasonably influenced by factors and tradeoffs beyond the quality or findings of an HIA.

Although HIA does not guarantee particular decision outcomes, providing publicly available information on health effects clearly is a mechanism of influence. Thomas Jefferson famously stated that “information is the currency of democracy.” In the case of EIA under NEPA, the purpose of the process was to give environmental consequences due consideration (Yost 2003). Although the courts observed that NEPA provides protection only from the harm of uninformed decision-making, not from adverse environmental consequences themselves, informing decisions has substantial power. Institutional rules for EIA have opened decision-making to public scrutiny, raised the profile of environmental considerations, and altered the norms and practices of public and private organizations in a way that is more protective of the environment (Canter and Clark 1997; Cashmore et al. 2007).

Given that HIA practitioners are not typically in decision-making positions, effective and broad communication of findings is essential to the informational objectives and to later influence on decision-making. Communication of findings may be optimal when there is an opportunity for assessors to have discussion with decision-makers and stakeholders. Effective dissemination may require educating decision-makers about the public-health evidence underlying conclusions and may require consideration of and response to criticisms about the findings or about the efficacy or feasibility of recommendations. Many others, apart from practitioners, may be in strong positions to communicate findings of HIA and their importance in the decision-making process. The accounting of health effects by HIA should allow the public and stakeholders to use information in the political process to advance health interests. The political use of HIA evidence—like other types of information disclosed to the public—should be viewed as a normal mechanism of its influence on decisions.


This chapter has thus far discussed HIA as it is practiced outside the context of EIA. NEPA and some SEPAs explicitly require the identification and analysis of health effects when EIA is conducted, and there are various views on how HIA might be related to or support health-effects analysis in the EIA process (see Appendixes A and F for further discussion). Although the scope of health-effects analysis has been limited in U.S. EIA practice, some argue that greater use should be made of NEPA and related state laws as a mechanism for health-informed policy-making given that it has the same substantive ends as HIA (Bhatia and Wernham 2008; Wernham 2009; Morgan 2011). Others, however, contend that EIA has become too rigid a practice to accommodate the attention and resources needed for conducting a comprehensive analysis of health effects (Cole et al. 2004) and that attention should be focused on the independent practice of HIA.

The committee is keenly aware of the time and resources that NEPA compliance can entail. However, assessment of direct, indirect, and cumulative health effects in EIA under NEPA and many SEPAs is a matter of law, not discretion, when it is likely to add important information that is relevant to decision- making (see Appendix A for further discussion). Therefore, when legal requirements call for an integrated analysis of health effects in the EIA process, this analysis should be conducted in observance of the same procedures and standards as for any other environmental or social effects being considered. In the case of health, those procedures would arguably mirror the general steps of HIA as described in Chapter 3 and would include a description of the baseline health status of the population; an analysis of the direct, indirect, and cumulative health consequences of the proposed action and alternatives; and a consideration of potential mitigation measures to address the health concerns identified by the analysis. If adequately conducted, the steps would be consistent with and might be considered equivalent to conducting an HIA.

To date, however, despite the requirements for the analysis of health effects in EIA, the consideration of health effects in EIA practice has been limited, and public-health experts have rarely been involved in the EIA process (Davies and Sadler 1997; Steinemann 2000; Hilding-Rydevik et al. 2006). The limited practice may partly reflect that historically, NEPA practice has been shaped primarily by pressure and litigation brought by environmental groups, and public- health advocates have only rarely demanded health-effects analysis. The limited practice also may reflect the resource constraints facing many public-health departments and more generally the lack of familiarity with EIA practice. Challenges to changing EIA practice to include more substantive health analysis include resistance on the part of agencies leading EIA to invest time and resources in routine health analysis, lack of familiarity with or expertise in public health on the part of agencies that commonly lead EIAs, and limited relationships with local, state, and tribal health authorities or others that have the capacity to conduct public-health analyses (Cole et al. 2004; Hilding-Rydevik et al. 2006; Corburn and Bhatia 2007; Bhatia and Wernham 2008). Because of those challenges, some HIA practitioners have voiced concern that, in contrast with independent HIA, integrating health into EIA might produce a narrow consideration of health effects (Cole et al. 2004). Furthermore, it is possible that agencies responsible for EIA may give less importance to health effects than to other environmental concerns; consider only health effects that are quantifiable with traditional methods, such as human health risk assessment; or allocate insufficient funding for health-effects analysis. Those concerns are valid, but the committee notes that the problem is not unique to the setting of integrated EIA. Currently, HIA conducted independently of EIA has no mechanism to monitor or ensure the adequacy of resources and breadth of analysis, and like EIA, the scope of HIA has been limited by practitioner decisions and available resources (Dannenberg et al. 2008).

Considering those important challenges, the committee concludes that improving the integration of health into EIA under NEPA and related state laws is needed and would serve the mission of public health and the goals of HIA. Federal agencies file thousands of EIA documents each year. Decision-making that is subject to EIA requirements at the federal and state levels includes a wide array of projects, programs, and policies that have broad importance for health. Furthermore, health issues are among the most common concerns raised by affected communities.

Agencies formally responsible for conducting EIAs and practitioners in the field of public health have an interest in improving the consideration of health in EIA. When health effects are relevant to a proposed action, agencies responsible for conducting EIA should seek out appropriate public-health expertise and should invite tribal, federal, state, or local health agencies to participate as cooperating agencies (40 C.F.R Sections 1501.6, 15018.5). Adequate resources should be accorded to health-effects analysis in EIA. Similarly, public-health officials need to take a more active role in EIA by offering appropriate information and expertise to aid the analysis.

Recent experience in the field has demonstrated that a greater consideration of direct, indirect, and cumulative health effects can be accomplished in EIA if the associations described are well supported by public-health theory and evidence (Wernham 2009; Bhatia and Wernham 2008; Morgan 2011). The official submission of findings by public-health agencies into the public record (for example, via public comment on draft environmental documents) has triggered comment and analysis by responsible agencies (Bhatia 2007). Interagency partnerships that have involved public health during an EIA have reduced skepticism on the part of agencies unfamiliar with public health and HIA, have fostered a broader shared understanding of potential health effects, and have led to health-protective mitigations and alternatives to the proposals that were assessed (Wernham 2007; Bhatia and Wernham 2008; Morgan 2011). In several cases under both NEPA and the California Environmental Quality Act, the scope of health effects and alternatives considered has been substantially augmented with the financial resources and expertise needed to conduct related analyses. In other cases, health-effects analyses have trigged substantive mitigations. There remain, however, substantial opportunities to improve the consideration and analysis of health effects under NEPA and SEPAs. Conflicts and negotiation of interests among environmental assessors and health professionals concerning values, objectives, scope, and use of information should be expected in the course of developing a stronger integrated practice (Morgan 2011).

Anecdotally, some concerns have been raised that broadening the scope of health analysis in NEPA may increase the potential for litigation. The committee finds little factual support for that view; indeed, only rarely has EIA litigation been based on inadequacy of health analysis. Indeed, the failure to address potentially important effects and substantive concerns is a leading reason for litigation under NEPA and may result in an order to the agency to address the omissions; this could cause delays in projects. Given that there is increasing attention to the relationship between public policies and health in the United States, the failure to address potentially important health effects may leave agencies more vulnerable to litigation; ensuring a comprehensive analysis of health in EIA may be a good way for agencies to avoid such risks.


  • Although there are many definitions of health, there is a growing consensus that health at the individual and population levels is shaped by a combination of genetic, behavioral, social, economic, and environmental factors. It is essential that those determinants be considered in defining the boundaries of HIA.
  • It is not necessary or appropriate to conduct HIA for all decisions at the local, state, or federal levels; however, restricting the spectrum of HIA practice to particular decision types, institutional sectors, decision scales (for example, policy, program, or plan), or jurisdictional levels or to specific health issues is not warranted. The use of HIA should be focused on applications in which there is the greatest opportunity to protect or promote health and to raise awareness of the health consequences of proposed decisions.
  • The committee finds that three strategies should help to improve the validity of health-effects predictions made in the context of varied evidence: consider diverse evidence sources by using expertise in multiple disciplines, assess the quality of available evidence, and implement a strategy for assessing and managing uncertainty.
  • Quantitative estimates of health effects in HIA have a number of desirable properties, but it is impractical to expect quantitative estimates in all applications of HIA given the sparseness of quantitative data on associations between many policy decisions and health.
  • An HIA that analyzes multiple dissimilar health effects should describe and characterize each effect separately and consider ways to provide aggregate or summary measures of dissimilar effects.
  • Although HIA is not a cost-benefit analysis, economic valuation of health effects may be requested by decision-makers and should be considered when relevant data are available. As with any HIA component, economic valuation should be provided with a discussion of key assumptions and methodologic limitations.
  • The committee emphasizes the importance of stakeholder engagement and participation in HIA. Information gained through stakeholder involvement can help to focus the scope of the HIA and improve its quality and specificity by highlighting local living conditions, prevalent health issues, and potential effects that might not be visible to practitioners outside the community.
  • A formal peer-review process for HIA could increase the acceptability or utility of conclusions on health effects or related mitigations and should be considered when the benefits of added scrutiny and rigor would outweigh the disadvantages of added delay and process.
  • To the extent feasible, practitioners conducting HIA should strive to avoid real and perceived conflicts of interest. It may be useful for future practice guidance to establish a clear line between the practitioner’s role in conducting HIA and later advocacy of particular decision outcomes. A dedicated public funding source and a process of independent peer review of HIA may help in managing or mitigating conflicts of interest.
  • HIA aims to influence attitudes and preferences and leads to actions that support health, but HIA may not change decisions when health is only one of many considerations. Conducting HIA as a mechanism for advocacy may compromise support for and legitimacy of the practice.
  • Improving the integration of health into EIA practice under NEPA and related state laws would serve the mission of public health and the purpose of HIA and EIA. Despite known challenges, agencies responsible for EIA and public-health practitioners share responsibility for improving the consideration of health effects in EIA practice. However, to ensure reasonable priority of health issues under NEPA, public-health agencies should be afforded a substantive role in the scoping and oversight of health-effects analysis in EIA, and health-effects analysis must be afforded resources commensurate with the task.
  • The committee concludes that any future policies, standards, or regulations for HIA should include explicit criteria for identifying and screening candidate decisions and rules for providing oversight for the HIA process; such criteria and rules would promote the utility, validity, and sustainability of HIA practice.


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The committee notes that although screening is considered an essential step in the HIA process, there is little published documentation or evaluation on the implementation of the screening step and thus little information on cases in which HIA might have been considered and not conducted. Some but not all HIA reports explain the rationale for conducting the assessment, but still there is little understanding of why HIAs have or have not been pursued.


The committee notes that distributional effects can be evaluated descriptively or quantitatively, and available statistical techniques enable relationships among impact inequalities and socioeconomic or demographic factors to be examined quantitatively (Kakwani et al. 1997; Mitchell 2005).


The committee distinguishes between advocacy (that is, trying to influence the decision outcome) and explaining or educating decision-makers on the findings and recommendations made in an HIA.


The committee notes that revisions might be made in a proposal or its alternatives in anticipation of an HIA being conducted; such changes might not ultimately be considered to be a result of the HIA but might not have occurred if the HIA were not planned.

Copyright © 2011, National Academy of Sciences.
Bookshelf ID: NBK83548


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