Sliding scales for assessing and communicating human and ecological risks and complexities for restoration, remediation crises, and decisions

Abstract

Many lands were degraded or destroyed by human activities, including contamination from industry and military facilities. The United States and other industrialized counties have legacy wastes remaining from the Second World War, the Cold War, and industrialization. There is increasing need to return degraded land to suitable future land uses, including ecological parks and preserves. This paper proposes a conceptual model of the different levels of information needed to understand the risk to human health, the environment, and ecological resources. I propose a four-part approach: 1) general model for assessing ecological resources, 2) model for assessment needed for remediation or restoration projects, 3) a sliding scale, conceptual model for causes, events, and sources that lead to exposure and risk, and 4) an additional step that includes environmental justice (equity, diversity and inclusion) as a necessary consideration of traditional exposure assessment. While the factors involved in ecological risk assessment are well established, the combination of human health, ecological health, and environmental justice determining risk for remediation or restoration projects is not. Major factors useful for human health, environmental, and ecological evaluation include causes, events (earthquakes, accidents, chemical releases), sources, exposure, and informational challenges, as well as barriers to exposure. I propose that exposure through an environmental justice (diversity, equity, and inclusion) lens should be a key component of risk assessment. Each of these factors involves a sliding scale or continuum that must be considered in evaluating risk and communicating with the regulators, resource trustees, land managers and the public. The conceptual model also serves as a template for obtaining information about the environment that will be useful for communicating the importance of different risk factors. The model was developed for consideration of remediation on Department of Energy lands, it can be applied more broadly to other projects.

1. Introduction

The United States and many other countries face the cleanup of hazardous wastes sites. In the United States, for example, radiologic and chemical contamination remaining from the Second World War, the Cold War, and from other industrialization occur in nearly every state. There is growing pressure to reclaim degraded lands (Galvani et al. 2016). The task of determining when and how to remediate hazardous waste sites falls to state and federal governments, Tribal governments, public policy makers, regulators, human health agencies, resource trustees, and the public. Remediation requires detailed funding, planning, and implementation that may require years or decades. While governments want to clean up contaminated lands to productive future land uses, this cleanup must protect the health of humans and the environment before, during, and after cleanup and restoration (EPA 2004; WHO 2917). Determining whether people or eco-receptors, and the larger ecosystem, are at risk is a difficult task, and involves balancing among different objectives, including ultimately future land use and sustainability (Sinnett et al. 2022).

There are clear methods for determining risk to humans from particular chemicals or a suite of chemicals, and many of the same methods or techniques can be used for different species of plants or animals. These include biomarkers, bioindicators, and endpoints from the whole animal to the cellular level (NRC 1983, 1993, 2000a; EPA 1995, 1997a,b). Similarly, there are methods for evaluating ecological risk (NRC 1995, 2000b; Norton et al 1992; Bartell 2006), including the ecological resources that people value (Costanza 2014, 2017). The inclusion of stakeholders was initially proposed by the Presidential Congressional Commission on Risk Assessment and Management (PCCRAM 1997) and others (Renn et al. 1993; Burger 2011; Goodman and Thompson 2017) to improve risk management. Overall integration of human and ecological health risk assessment, including stakeholders and environmental justice is essential to achieve sound scientific decisions about remediation and restoration (Burger 2008: Burger et al. 2008; Cvitanovic et al. 2016). Even so, examinations of the literature conclude that there are few studies that focus on sustainable remediation, with the inclusion of stakeholders at all levels (Braun et al. 2019). Clearly, governmental agencies, conservationists, and the general public want the remediated or restored systems to be sustainable (Cappuyns 2016, Renn 2006). In considering risk governance more broadly, Renn (2006, 2015) also suggested the importance of inclusion of societal context and the categorization of risk-related knowledge. Consideration of these two, however, is not necessarily a focus on how governance and risk assessment relate to risk communication.

This paper proposes: 1) a general model for assessing ecological resources, 2) a model for assessment needs for remediation or restoration projects, 2) a conceptual sliding scale model for the causes, events, and sources that lead to exposure and risk for human health and ecological resources, and 3) an additional step that includes environmental justice (equity, diversity and inclusion) as a necessary consideration of traditional exposure assessment. I suggest that the latter two should be conducted together and in an iterative manner involving a range of stakeholders. Further, combining sliding scale for factors contributing to risk will allow the public to determine for themselves where on the sliding scales each event or crisis falls, providing more nuanced understanding of risks. Always adding environmental justice factors will further provide assurances to the public that diversity and equity are being considered. The approach presented in this paper adds to the approach taken by the International Risk Governance Council (Renn 2006, 2015) and adds an approach and tool to use for communication with a range of stakeholders.

At the end of the Cold War, and the era of secrecy for the Department of Energy (DOE), the Environmental Management (EM) program was created within the Department of Energy to manage their legacy cleanup program (Crowley and Ahearne 2002). The Department of Energy (then called the Atomic Energy Commission) had its origin in World War II, with the development of the first nuclear device that heralded an era of development of weapons (DOE 2022a,b; Krahn 2022). With the recognition that there was nuclear and chemical contamination on DOE sites, the DOE-EM made Tri-Party agreements with the U.S. Environmental Protection Agency (EPA) and state representatives that established cleanup milestone long before the actual contamination on sites was characterized. This created legal and social problems when the full extent of contamination became known, which in turn influenced the time, logistics, and planning of site remediation. While DOE and many other agencies and organizations developed risk assessment paradigms (references above), I suggest in this paper that developing a sliding scale or continuum of the risk factors for risk assessments, and the resulting risk communication strategies, would help reassure the public that DOE and others are protective of human health and the environment. Finally, this paper provides a conceptualization for expanding the usual risk assessment paradigms, and thus the results use references to develop the components of assessment.

2. Background on the Department of Energy

With the ending of the Cold War in the 1980s, the Department of Energy and the U.S. Federal government recognized that there were important ecological resources on their lands, some areas of the large DOE sites were designated by Congress as National Environmental Research Parks (DOE 1994a,b). The purpose was partly to provide research funds to study the effects of radionuclides and other contaminants on species and communities, to assess the value of ecological resources, and to study species, populations, and ecosystems on DOE lands generally. On the large DOE sites (i.e. Hanford Site in Washington, Idaho National Laboratory in Idaho, Savannah River Site in Georgia), only about 10 % of DOE’s land holdings were industrialized. The undeveloped, uncontaminated buffer DOE lands have valuable ecological and eco-cultural resources (Brown 1998; Dale and Parr 1998; Whicker et al. 2004; Burger et al. 2006; NPS 2017, ECA 2020), and their importance should be considered in remediation operations and future land use planning.

Another DOE development was the creation of Citizens Advisory Boards and the inclusion of stakeholders to aid DOE in their decision-making process, and to serve as a method of communicating with the public (NRC 2008, Burger 2011; DOE 2017, 2019). DOE seeks success through public engagement, to serve communities, stakeholders and Tribal Nations while protecting natural, cultural and historical resources (DOE 2022a,b).

DOE has cleaned up 91 sites at a cost of about $170 billion (Government Accounting Office 2019) and continues to do so. There are cleanup projects at 16 sites that will require at least another 50 years to complete, at an estimated cost of $377 billion (NRC 2000a; DOE 2019). Although DOE is making enormous progress toward meeting cleanup goals while protecting human health and the environment, there is still a long delay (NRC 2000a; DOE 2022b). Further, with a changing environmental (climate change) and social (adding new stakeholders, environmental justice claims and needs), new tools are needed. Developing tools to continually evaluate the important resources on DOE lands consistently and transparently provides assurances to regulators and the public of continued environmental protection (Burger 2019; Burger et al. 2019).

3. General approach and methods

The ideas expressed in this paper are derived from working at several Department of Energy sites on environmental remediation and restoration for over 25 years by the authors, as well as experiences at chemical and industrial plants. This includes projects and discussions with the Department of Energy, Environmental Protection Agencies, U.S. Fish and Wildlife Service, National Oceanographic and Atmospheric Administration, Tribal governments and members, State resource and regulatory agencies, environmental justice community neighbors, and the public. The authors were informed by both the refereed and the gray literature, as well as by public meetings and Citizen’s Advisory Boards. Ecological risk assessment paradigms have been developed by Burger and others from the team on risk assessment issues (Burger 2006, 2019, 2022a; Burger et al. 2006, 2015, 2019, 2021, 2022a,b), environmental justice (Bullard 1990; Burger 2011; Burger and Gochfeld 2011; Burger et al. 2008, 2010, 2022b), and risk communication (Burger et al. 2020, 2022b), among others.

We first present a broad, current view of protecting the environment and ecological resources and present a conceptual model for considering the different levels of information needed to assess risk to ecological resources in a broad sense that can be used to think about the information needed to communicate the value of ecological resources on currently contaminated lands, and the potential risk to ecological resources from a crises or event. The model is then refined to include environmental justice communities such that diversity, equity, and inclusion are always considered.

4. Results

4.1. Conceptualization of factors influencing ecological risks during remediation and restoration

Remediation and restoration are mission- or objective driven. Remediation and restoration do not occur in a vacuum, but are initiated by someone, be it governmental (U.S., Tribal), non-governmental or the public. That is, there is a project to remediate a contaminated site to reduce risk to humans and the environment (Crowley and Ahearne 2002; DOE 2002), to remediate a contaminated chemical plant to some pre-determined future land use (EPA 1997a,b), or to conduct restoration on some degraded ecological land to restore it to its previous condition (Cairns 1994; Baird 2005; Doren et al. 2009a,b). This is equally true for restoration in that governmental agencies, non-governmental agencies, or the public have determined that degraded or destroyed land should be restored to a functioning ecosystem, either human-dominated or more natural. The traditional view is to remediate or restore the land or ecosystem to its original state, although who determines what is “original” is open to debate. That is, should it be restored to its condition 25, 50, 100 or more years ago, or to an idealized state for that ecosystem type; who decides (Palmer and Ruhl 2015).

Traditional ecological assessment involves characterizing components of eco-receptors from species to communities (NRC 2000b; Duke and Taggard 2000; Bartell 2006; Vaananen et al. 2018). Ecological risk assessment usually includes assessment (what is the current condition), as well as monitoring data (DOE 2013). Monitoring involves the repeated assessment of ecological indicators over time (Kateregga and Sterner. 2007; Jurgens et al. 2012; DOE 2013; EPA 2019a). That is, an example of assessment is how many birds are present in one year, while monitoring is changes in the number of birds over time (Fox 2001; Frederich et al. 2002; Burger and Gochfeld 2016a). These phases (assessment, monitoring) are well established and in practice. Often the effect of contaminants (chemicals and radionuclides) is examined in the risk assessment. However, two important components not usually considered are added: 1) initiating events, and 2) barriers or blocks to exposure or ecosystem disruption (Fig. 1).

Fig. 1.

Traditional process and data needed to evaluate risk to ecological resources. This is the ideal process, and some steps may not always be necessary.

Initiating events are those events that cause a shift in the risk to ecological resources, such as storms, fires, or earthquakes that could disrupt species or ecosystems, as well as descriptions of blocks to ecosystem disruptions or transport of chemicals (e.g. rivers, wide roads, lack of aquatic connectivity) (Burger and Gochfeld 2016b; Greenberg et al. 2018). An initiating event, such as a severe storm can cause flooding that wipes away an existing ecosystem, a fire can kill trees and open the forest to more sunlight and invasive species, or drought can kill some existing vegetation leading to shifts in the relationships among native plant species or among native species and invasive plant species (Mooney and Hobbs 2000; Siegert et al. 2001; Doren et al. 2009a; Larsen et al. 2011; Burger 2022b).

Barriers are natural or anthropogenic blocks to disruption or contamination (Harclerode et al. 2016). For example, a wide road may dampen the movement of snakes that do not move across roads or are killed doing so, a wide river may serve as a barrier for the spread of some invasive plants or to small, non-mobile invertebrates, and a mountain range may prevent plants or animals from dispersing over it (Clevenger et al. 2003; Clark et al. 2010). When considering the spread of contaminants, engineered barriers are often used, such as covering a toxic waste dump with impermeable covers, moving waste to a lined pit that can be covered, or containing waste in drums or other containers (Albrecht and Benson 2001; Sellin and Leupin 2013; Claret et al. 2022). Both types of barriers are subject to disruption themselves: a river can dry up and allow access, some snakes may cross the road and become established, and a mountain range may become less of a barrier with global climate change or building of roads. Similarly, engineered barriers can fail, fall apart, or not be maintained. Still, it is important to note whether there are barriers to disruption and contaminant flow because it brings awareness of future potential problems that might be managed. Further, barriers for some species can become conduits for others to move into relatively pristine environments (Resasco et al. 2014). For example, invasive species can be brought into pristine habitats by the tires of trucks or other vehicles, and they can be brought from one country to another as passengers on ships or airplanes (Burger and Gochfeld 2016b)

4.2. Broadening risk and communication to include human health

With time, concepts of environmental health and risk assessment have broadened. Traditional risk assessment for human health initially involved computing cancer and non-cancer risk to individual humans (NRC 1983, 1993), and ecological risk involved using toxicity thresholds for determining effects for individual indicator species and populations (NRC 2000b). However, both human health and ecological health are larger than toxicity levels for individuals, but include aspects of populations, communities, and ecosystems, and even landscape-scale issues (Forman 1995). Protecting humans includes not only the physical aspects of human health but well-being, public health, and cultural and societal aspects. Protecting the environment includes not only the physical environment and the goods and services it provides, but the health and well-being of species, populations, ecosystem, and landscapes (Jessel 2006; Bunnell 2008; Dorean et al. 2009b; Costanza et al. 2017)(Fig. 2).

Fig. 2.

Relationship between different types of risk assessments required before, during and after restoration and remediation. The diagram includes largely the ecological aspects of human health protection, and not traditional physical exposure assessments (e.g. cancer and non-cancer endpoints).

The process of assessing ecological risk and determining its role in remediation and restoration decisions is far more complex for ecological resources because of the diversity of organisms, populations, ecosystems, and landscapes. Balancing the risks to humans and the environment is also complicated by cultural, religious, and economic values, which in themselves differ from the usual human health risk assessment. There are many reasons to conduct ecological risk assessments, such as for development, recreation, management of species, or invasive species control, but ecological assessment is particularly critical for making remediation decisions because often a functioning ecosystem has developed on contaminated and/or abandoned land, and remediation may disrupt or destroy the current ecosystem, or harm ecosystems adjacent to the contaminated site (Whicker et al. 2004; Chan et al. 2012; Burger et al. 2019). The methods to evaluate the risk to ecological resources on contaminated sites include traditional single-species assessment, population and community assessments, and landscape assessments (patch size and connectivity), as well as barriers to contaminant transfer (man-made and natural), risks from contaminants, risks from remediation itself, and how to reduce risk to ecological resources during remediation. It is also critical to take into account the goods and services ecosystems provide, and the eco-cultural values of eco-receptors and ecosystems. The information needed for such evaluations requires attention to indigenous values and scientific perspectives, as well as more familiar environmental science that examines risks the general public as well as to overburdened communities. There are many definitions of overburdened communicates, but EPA (2021) uses criteria such as: 1) communities that have at least 35 % of the households qualifying for low-income housing, 2) communities where at least 40 % of the residents identify as minority or members of a state-recognized Tribal community, or 3) communities where at least 40 % have limited English proficiency.

Assessment for any actions should include both the fuller characterization of human health and the environment together (CDC 2022), and human health and the environment should be protected before, during and after remediation and restoration (Fig. 2). When permits are authorized, there are usually constraints on any human or ecological risks the operations may pose, but the efficacy of protective measures may not be assessed after completion of the project. Moreover, many projects may take years or decades, as for example is the case for the Department of Energy’s Hanford Site and some of their other larger sites (NRC 2000a; DOE 2000a). In those cases, care should be given to assessing risks to the eco-receptors, associated ecosystems, and the human uses and interactions that occur because of ecological resources. That is, people are exposed not only through air and water, but through products they use from ecosystems, and from non-consumptive uses (walking, running, recreating, and enjoying religious, aesthetic experiences or existence values) (Davidson 2013).

4.3. Broadening the risk concept to encompass dichotomies and continuums.

To understand the potential risk to species and ecosystems it is first important to understand the context of the event, be it natural or anthropogenic, acute or chronic, or driven by an accident or not, as well as by the type of stressor (e.g. fire and smoke, chemical, radionuclides, virus) (Fig. 3). Events act through potential sources of exposures, which can result in acute crises, or chronic crises. In many cases an acute event becomes chronic (as often happens with oil spills), and a crisis can occur when a long-standing or chronic exposure is identified and gains sudden notoriety (e.g. lead in drinking water in Flint, Michigan, Zahran et al. 2017). Increasingly risk communicators should consider preparedness for disasters and emergencies as well as chronic exposures (NRC 2023).

Fig. 3.

A conceptual model for the causes, events, and sources that lead to exposure and risk for ecological resources. The model has a series of slides (= black circles) that slide back and forth, depending upon the range within each section, and the description of the current crises or chronic exposure. The consequences or effects obviously depend upon where the slide is located at each section (e.g. causes, events, sources, exposures). The circle on each blue bar can slide back and forth across the continuum to indicate the variation in those factors.

The information “communicators” need to evaluate risk to ecological resources before communicating with the public and others includes not only the events, sources, and types of exposures, but importantly, the key ecological resources at risk (shown as informational challenges on Fig. 3). For understanding the risk to ecological resources, it would be useful to think about the different aspects of events that lead to exposure and risk. The types of events, and whether they are natural or anthropogenic, or some combination thereof, partly determine the sources of exposure, the degree of exposure, and the kinds of ecological effects. The model is a step toward describing the complexity of factors contributing to risk (Parrot 2010; Cappuyns 2016) and providing a method of demonstrating the complexities. To communicate useful information about risks, it is necessary to know what information people already possess, and what they need. Each slide (black ring on Fig. 3) can move along the blue line, back and forth, depending on the conditions. Obviously, the severity of consequences and effects varies depending on each level of information (causes, events, sources, and exposures). Further, I suggest that thinking about the causes on a continuum of natural to anthropogenic allows people engaged in assessment or risk discussions to consider the relative role of different components and how they might be reduced or mitigated. Fires, for example, can be caused by a natural event (lightening), from a anthropogenic event (discarded cigarette), or a natural event (lightening fire) can be enhanced by buildup of fuel caused by local fire suppression (Siegert et al. 2001). Similarly, mercury is found naturally in oceanic waters, but the amount of mercury in the oceans and estuaries is enhanced by human activities and climate change (IPCC 2014, 2021a,b).

4.4. Adding the human community dimension to ecological evaluations

While the factors shown in figure 3 are often the ones considered during remediation, they are usually only identified as to cause (fire because of a cigarette), events (someone threw it out the window), and exposures (firefighters are exposed to particulates while firefighting), the placement of the risk event within the range of continuums may not be considered, which makes it less likely that risky events will be placed within the large framework of interacting events causes, and exposures. Figure 3 puts human dimensions only as information challenges for the agencies making the remediation decisions, for the communities advising the governmental agencies, and for the communicators of the remediation action or crisis event. In essence, a conceptual framework is needed that integrates different ecological, cultural, and social considerations (Sandifer et al. 2015; Virapongse et al. 2016; Harwell et al. 2019). I suggest that there should always be a more structured, recognized inclusion of environmental justice, in addition to considerations of ecosystem services, intrinsic value, existence values, and cultural/religious values, although these are critical (Harris and Harper 2000; Chan et al. 2012; Davidson 2013). This would lead to the increase of integration of natural and social science, especially for environmental management (Virapongse et al. 2016). Environmental justice indicators usually include demographic or ethnic shifts, mean income, the percent of a community that is minority, indicators of health, transportation inequities, and access to stores, medicines, medical care, and green spaces, among others (Holifield 2001, Chakraborty et al. 2016). Clearly environmental justice communities that include equity, diversity, and inclusion, should be part of the risk paradigm for both human and ecological risk evaluations, resource assessments and environmental planning, and EPA (2019a,b) has developed tools to begin this process.

In many instances, environmental justice is used as a lens to examine unfair burdens of chemical or radionuclide exposures, or to the undue presence of chemical plants and other industrial facilities or activities (e.g. ports, airports, railroads)(EPA 2009, 2019a). The same causes, initiating events, sources, and exposures lead to risk for ecological resources (Fig. 4), as well as eco-cultural resources and social and cultural resources, leads to rethinking ecosystem services (Harris and Harper 2000; Holifield 2001; Burger 2008, 2011; Chakraborty et al. 2016; Burger et al.2022a; Chan et al. 2012) and the relationship between these services and social and economic valuation (Davidson 2013). The model and inclusion of environmental justice in the exposure should be equally used for opportunities to be exposed to green spaces, parks, forests, and other ecosystems. That is, all people and all communities should have equal access to the positive benefits of ecological resources on contaminated, remediated and restored sites (Burger et al. 2022a).

Fig. 4.

A conceptual model for the causes, events, and sources that lead to exposure and risk for ecological resources, with the addition of an environmental justice lens to be included with any exposure assessment. The communication challenges for the model relate to having scientifically credible, up-to-date information for each component (causes, events, sources, exposures and environmental justice communities.

5. Discussion and conclusions

Assessing and managing environmental risks in a global context requires clear understandings and models of every aspect of risk, from framing the problem to define and implementing solutions. While there are several excellent risk assessment models, there are few that relate direction to sustainability (Braun et al. 2019; Sinnett et al. 2022), and fewer still that relate to the overall governance framework (Renn 2006, 2015). These all need to be combined with the opportunity, and indeed the necessity, of participation of a wide range of stakeholders from governmental agency personnel to individuals who are interested and affected. But there is also a strong need to include risk communication (and viable tools) as an important component of environmental risk management. The present ms provides some visual tools toward this end.

Environmental assessment and risk communication are often thought of as separate entities and are conducted by different agencies within any organization. Yet they are collaborative and iterative. Clearly, detailed ecological information and assessment can be a full-time job, with multiple agencies and individuals involved. Communication can also be a separate and independent department within any large governmental agency or company. However, in a crisis, whether acute or chronic exposures, the two have a similar goal – providing credible, scientifically-based information to relevant people to reduce risk. The contribution of this paper is to 1) add initiating events and presence of barriers to traditional ecological risk assessment, 2) expand ecological risk assessment to include more social and cultural components to eco-receptors, 3) consider that many of the factors contributing to a risk assessment (both ecological and human health) are continuums, and lastly, 4) to add a environmental justice lens to exposure assessment for both ecological resources and human health. These factors should be considered by risk assessors, risk communicators, land planners and managers, and environmental and public health scientists, and that they help provide a conceptual foundation for environmental decisions support (Reichert et al. 2015). Bearing in mind the complexity of exposure and risk (e.g. sliding scales and inclusion of environmental justice) will aid in describing hazards, threats and risks. Further, communicators often is imparted about an incident or event without perfect information, and communication may be multi-dimensional and not one-way (Kasperson 1986; Greenberg 2022).

The model that is presented places ecological assessment within a framework of human and ecological health and well-being that is itself multi-dimensional and involves different continua (e.g. natural to anthropogenic, acute to chronic). It also suggests that an environmental justice lens should be used not only for adverse effects, such as exposures to contaminants and other environmental exposures (noise, crowding, traffic), but for the positive benefits that ecological resources provide. That access to green environments has a positive effect on human health has been demonstrated (Condo et al. 2018). That is, distribution of the benefits of ecological resources to environmental justice communities may be important for both biodiversity conservation and human health (Martin et al. 2013).

While the model presented above was originally derived to explain ecological risks to the public, it is equally important to remember that in an acute crises, this information may relate to both human and ecological risk, and needs to be made available to all levels of stakeholders, including the responsible party, government officials (from local to federal), specific groups (e.g. community or conservation), the general public, and any unique communities, including environmental justice communities. It is perhaps most useful at a communication tool to foster multi-dimensional communication is a range of crisis and acute exposures that can be natural, anthropogenic or a combination of both. It can be used in both in-person communication, as well as in a range of social media where participants can play with the sliding scales and suggest/explore how the risks or benefits might vary as a function of the different continuum.