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A scientific workforce with cutting-edge skills is critical for the ability of the U.S. Environmental Protection Agency to carry out its mission to protect human health by identifying environmental hazards, evaluating risks to public health and ecosystems, and formulating effective methods for pollution control and prevention. To aid in the selection and hiring of premier scientists and engineers, in 2006, EPA first sought the ability to directly recruit world-renowned scientists and engineers from academia, private industry, and other government agencies under Title 42, Section 209, of the U.S. Code. Title 42 authorizes federal agencies to appoint highly qualified scientists and engineers outside of standard civil service positions. Congress reauthorizes the EPA Title 42 authority in 5-year increments. To guide decisions about the future of the program, Congress asked the National Academies to review past and current EPA use of Title 42 hiring authority and how the program might be improved. The report finds that EPA has used its limited Title 42 authority effectively since 2006 and that Title 42 authority has enabled the hiring of effective scientific leadership and improved the scientific capability and capacity to support the Agency mission. Furthermore, the report finds that Title 42 can help the agency in addressing future environmental complexities. In continuing to enhance its scientific workforce and maintain a position at the forefront of evolving scientific knowledge, EPA would benefit from Congressional approval for permanent Title 42 authority.

Fisheries are essential to the global economy and feed billions around the world; they, support individuals and communities, and sustain cultural heritages and livelihoods. Although U.S. fisheries have been managed for commercial fishing historically, there has been an interest more recently in better accounting for and meeting the needs of the diverse individuals, groups, and communities that rely on and participate in fisheries, or aspire to do so. At the request of the National Marine Fisheries Service, this report considers information needs and data collection for assessing the distribution of fisheries management benefits. Assessing Equity in the Distribution of Fisheries Management Benefits identifies information needs, obstacles to collecting information, and potential methodologies for assessing where and to whom the primary benefits of commercial and for-hire fishery management accrue.

Macroeconomic models, essential for decision making and federal budget planning, may not appropriately consider the wide breadth of climate-related impacts that potentially have large macroeconomic significance. Challenges integrating climate factors into macroeconomic analyses can stem from the complexity of macroeconomics, climate science, policy instruments, and their interactions. Although economists have made progress in developing tools to understand climate-related impacts on the macroeconomy, much of the climate and macroeconomic research has historically been conducted in disciplinary silos that can limit a holistic understanding of climate-related impacts on the macroeconomy. The National Academies of Sciences, Engineering, and Medicine, under the auspices of the Roundtable on Macroeconomics and Climate-Related Risks and Opportunities, convened a workshop on June 14-15, 2023, to consider current macroeconomic models and suggest opportunities that may improve the incorporation of climate-related factors into macroeconomic modeling. Through panels of invited speakers and an interactive breakout discussion, the workshop explored an array of macroeconomic models and potential pathways to integrate some of the physical and transition effects of climate change. This publication summarizes the presentations and discussion of the workshop.

Over the past century, the Everglades has been dramatically altered by drainage and water management infrastructure intended to improve flood management, urban water supply, and agricultural production. Less than half of the original Everglades remain, and these remnants compete for water with urban and agricultural interests, all the while being impaired by contaminated runoff. The Comprehensive Everglades Restoration Plan (CERP) was established in 2000 as a joint effort by the state and federal government to reverse the decline of the ecosystem. The multibillion project aims to restore the ecosystem over the course of 30 to 40 years by reestablishing the natural hydrological characteristics of the Everglades where feasible and ultimately creating a water system that serves both the natural and human needs of South Florida. Since 2004, a National Academies committee has provided a series of independent, peer-reviewed assessments of CERP progress. Implementation of CERP projects has occurred at a remarkable pace over the past two years due to record funding levels. Ecosystem responses are evident over large areas of the central and western Everglades after implementation of recent restoration initiatives. This progress in implementation has increased the importance of analyzing and synthesizing natural system responses. The committee review of ongoing progress highlights the need for rigorous scientific support for water quality improvement in stormwater treatment areas and modeling for a wider range of plausible climate conditions. Progress Toward Restoring the Everglades: The Ninth Biennial Review - 2022 recommends the development of a multiagency Everglades restoration science plan to ensure the needed tools, research, analysis, and synthesis are available to support critical restoration management decisions.

Virginia was one of the first major gold-producing states in the U.S., but it has seen only limited and intermittent gold mining activity in the last 70 years. Recent increase in gold prices and other factors have brought renewed attention to mining gold at both new and historical sites in Virginia. This report provides an evaluation of the gold deposits in Virginia, the probable modern mining techniques that could be used at such deposits, and whether existing regulations in the Commonwealth are sufficient to protect air and water quality and human health from potential impacts of gold mining activities. The report concludes that the regulatory framework of Virginia appears to have been designed for operations like crushed stone quarrying and sand and gravel operations, not gold mining. Thus, the current regulatory framework is not adequate to address the potential impacts of commercial gold mining and lacks an adequate financial assurance system, which poses a fiscal and environmental risk to the Commonwealth. Additionally, Virginia lacks opportunities for the public to be engaged in permitting processes and a modern system for review of environmental impacts from potential gold mining projects.

The South Asia region presents a confluence of major climate impacts and key security issues. From a weather and climate standpoint, the region experiences a wide range of hazards, such as the recent heatwaves, droughts, storms, and floods that have upended the lives and livelihoods of millions of people. From a demographic and socioeconomic standpoint, the region is experiencing rapid transformations and progress, even as fundamental challenges such as poverty and inequality persist. From a security standpoint, the region is the setting for a range of social and political dynamics that impact U.S. interests, including conflict at national and subnational levels; regional rivalries; and the imprint of global geopolitics. On October 26-27, 2022, the National Academies of Sciences, Engineering, and Medicine, under the auspices of the National Academies Climate Security Roundtable, convened a workshop to explore climate security in South Asia. Over two days, workshop participants considered some of the underlying climate, development, and geopolitical dynamics at play in the South Asia region; explored a set of historical case studies and future scenarios for climate change and security in South Asia; and they considered the available tools for analysis and forecasting climate-related risks. This publication summarizes the presentations and discussion of the workshop.

The Hanford Nuclear Reservation in the state of Washington produced about two-thirds of the nations plutonium for nuclear weapons from 1944 until the last reactor was shut down in 1987. The U.S. Department of Energy Office of Environmental Management (DOE-EM) manages the ongoing clean-up at Hanford and has built a plant to convert the high-level radioactive waste into a glass form (vitrification) for safe disposal. However, decisions remain about how best to treat and dispose of the low-level waste at Hanford, which comprises over 90% of the volume of waste. To inform its decision, DOE contracted with key Federally Funded Research and Development Centers (FFRDC), led by Savannah River National Laboratory, to carry out an analysis. This final in a trilogy of reports from the National Academies reviews the FFRDC third report released in January 2023. The review finds that the FFRDC team made a strong technical case that converting the supplemental low-level waste from the vitrification process to a grout form (like cement) is the best option in terms of cost-effectiveness and timeliness, and that off-site disposal of that grout is a valid option as it will be away from potable water. The FFRDC provided a useful framework to help decision-makers understand the issues and trade-offs of the disposal options and did an excellent job of isolating specific factual considerations that can be analyzed, often quantified, and compared with each other. The FFRDC chose to provide a purely technical analysis that excluded analysis of two important factors to be considered - securing regulatory permissions and public acceptance - treating them, for now, as uncertainties. Looking ahead, the DOE faces many uncertainties and should emphasize flexibility in its overall approach, allowing for multiple, redundant options and pathways, as well as the ability to change over time.

Formaldehyde is widely present in the environment and is one of the highest production chemicals by volume, used in manufactured goods including wood products, permanent press fabrics, and household products. It is also formed by combustion sources and is present in smoke from cigarettes and other tobacco products, and in emissions from gas stoves and open fireplaces. In carrying out its mission to protect human health, the U.S. Environmental Protection Agency (EPA) identifies and characterizes the health hazards of chemicals found in the environment through its Integrated Risk Information System (IRIS) Program, which has reviewed the human health hazards resulting from formaldehyde exposure in several assessments. This report is a continuation of guidance from the National Academies on draft IRIS assessments of formaldehyde and other aspects of the IRIS program. This report reviews the 2022 Draft Assessment with regard to its adequacy and transparency in evaluating the scientific literature, use of appropriate methods to synthesize the current state-of-the science, and presentations of conclusions that are supported by the scientific evidence. The report concludes that the 2022 Draft Assessment follows the advice of prior National Academies reports and that its findings on hazard and quantitative risk are supported by the evidence identified. However, revisions are needed to ensure that users can find and follow the methods used in each step of the assessment for each health outcome.

The world confronts an existential challenge in responding to climate change, resulting in an urgent need to reduce greenhouse gas emissions from all sectors of the economy. What will it take for new and advanced nuclear reactors to play a role in decarbonization? Nuclear power provides a significant portion of the worlds low-carbon electricity, and advanced nuclear technologies have the potential to be smaller, safer, less expensive to build, and better integrated with the modern grid. However, if the United States wants advanced nuclear reactors to play a role in its plans for decarbonization, there are many key challenges that must be overcome at the technical, economic, and regulatory levels. Laying the Foundation for New and Advanced Nuclear Reactors in the United States discusses how the United States could support the successful commercialization of advanced nuclear reactors with a set of near-term policies and practices. The recommendations of this report address the need to close technology research gaps, explore new business use cases, improve project management and construction, update regulations and security requirements, prioritize community engagement, strengthen the skilled workforce, and develop competitive financing options.

After the Exxon Valdez oil spill in 1989, advancing oil pollution research and technology to limit the environmental impacts of oil spills became a national and international priority. Congress responded by enacting the Oil Pollution Act of 1990 and forming the Interagency Coordinating Committee on Oil Pollution Research (ICCOPR) to coordinate research for preventing, planning for, responding to, and mitigating the effects of oil pollution on the environment. To achieve this end, ICCOPR published the oil pollution research and technology plan to guide research and funding priorities in 1992, with updates released over the years, most recently, the 2022-2027 Research and Technology Plan. This new report provides advice and guidance on the approach, structure, adequacy, and implementation of ICCOPR 2022-2027 Research and Technology Plan. Coordinated research efforts are necessary so knowledge and capacity related to oil spill prevention, preparedness, response, mitigation, and restoration can be advanced. Future updates of the plan should utilize a more streamlined, transparent, and community-driven development process including development of an oil pollution research dashboard and inclusion of metrics to assess and communicate progress on oil pollution research priorities. ICCOPR should also initiate processes to allow for open-water field trials when appropriate. The report recommendations were developed to assist ICCOPR with developing a Research and Technology Plan that can be widely used to promote progress, coordination, and collaboration on priority oil pollution research needs within the United States and globally - research needs that are important for improving knowledge, capacity, and regulations to safeguard the environment.

The predominant way of making steel in the United Sates is by using an electric arc furnace (EAF) to melt scrap steel, which results in the formation of a rock-like material called slag. Among its various applications, EAF slag is used in a loose or unencapsulated form as ground cover material for residential landscaping. However, the slag generated from the EAF process can contain toxic metals, which can be hazardous to human and environmental health. This report, conducted at the request of the U.S. EPA, discusses the relative hazard of key EAF slag constituents, the extent to which they may be released into the environment, and important aspects in assessing human exposures and risk. Due to uncertainties in the current evidence stream, the report was unable to make an overall characterization of risk related to unencapsulated EAF slag use in the United States and cautions against making generalizations from conclusions in published risk assessments. The report also identifies research needs to better understand factors considered to have the potential to contribute to the highest risks from the use of unencapsulated EAF slag, such as human exposure to dust particles that may be released over time from applied slag.

The Hanford Nuclear Reservation, where about two-thirds of the nation's weapons plutonium was produced from 1944 to 1987, is the site of the largest and most complex nuclear cleanup challenge in the United States. Section 3125 of the National Defense Authorization Act for Fiscal Year 2021 calls for a Federally Funded Research and Development Center (FFRDC) to develop a framework of decisions to be made among the supplemental treatment technologies, waste forms, and disposal locations for low-activity waste in the Hanford tanks. In addition, Section 3125 calls for the National Academies of Sciences, Engineering, and Medicine to provide a concurrent, independent peer review of the ongoing FFRDC analysis. This review report, the first of three to address the Congressional mandate, focuses on the technical quality and completeness of the FFRDC's draft framework.

The U.S. Environmental Protection Agency's (EPA) Integrated Risk Information System (IRIS) program develops human health assessments that focus on hazard identification and dose-response analyses for chemicals in the environment. The ORD Staff Handbook for Developing IRIS Assessments (the handbook) provides guidance to scientists who perform the IRIS assessments in order to foster consistency in the assessments and enhance transparency about the IRIS assessment process. At the request of the EPA, this report reviews the procedures and considerations for operationalizing the principles of systematic reviews and the methods described in the handbook for determining the scope of the IRIS assessments, evidence integration, extrapolation techniques, dose-response analyses, and characterization of uncertainties.

The Hanford Nuclear Reservation in Washington state, which produced plutonium for nuclear weapons from 1944-1987, is the site of the largest and most complex nuclear cleanup challenge in the United States. The U.S. Department of Energy's Office of Environmental Management (DOE-EM) is responsible for managing the cleanup of the radioactive and other hazardous wastes stored in 177 underground tanks at the site. DOE plans to use vitrification, or immobilization in glass waste forms, for all of the high-level radioactive waste at Hanford. However, because the volume of'low-activity waste'exceeds DOEs capacity limits for vitrification, DOE must decide how to treat the remaining'supplemental low-activity waste'(SLAW) so that it can be safely disposed in a near-surface disposal site. To help inform its decision, DOE contracted with a Federally Funded Research and Development Center (FFRDC), led by Savannah River National Laboratory, to analyze and report its findings about three potential alternative technologies. At the request of Congress, the National Academies reviewed the FFRDC report in terms of its value for decision making and how well it meets various Congressional requirements related to Hanford cleanup. The review concludes that the FFRDC report is overall very strong, provides a useful framework for evaluating the technology options, and is responsive to guidance from the first National Academies review. The framework provides for structured side-by-side comparisons, using relevant criteria, of a limited number of alternatives for managing SLAW. Recommendations for strengthening the report include estimating a lifecycle cost profile for constructing and operating each alternative, and providing more in-depth discussion on potential challenges that may need to be addressed in obtaining the necessary various regulatory approvals.

Oil and natural gas represent more than 50 percent of the worldwide energy supply, with high energy demand driven by population growth and improving standards of living. Despite significant progress in reducing the amount of oil in the sea from consumption, exploration, transportation, and production, risks remain. This report, the fourth in a series, documents the current state-of-knowledge on inputs, fates and effects of oil in the sea, reflecting almost 20 additional years of research, including long-term effects from spills such as the Exxon Valdez and a decade-long boom in oil spill science research following the Deepwater Horizon oil spill. The report finds that land-based sources of oil are the biggest input of oil to the sea, far outweighing other sources, and it also notes that the effects of chronic inputs on the marine environment, such as land-based runoff, are very different than that from an acute input, such as a spill. Steps to prevent chronic land-based oil inputs include reducing gasoline vehicle usage, improving fuel efficiency, increasing usage of electric vehicles, replacing older vehicles. The report identifies research gaps and provides specific recommendations aimed at preventing future accidental spills and ensuring oil spill responders are equipped with the best response tools and information to limit oil's impact on the marine environment.

Transportation is the largest source of greenhouse gas emissions in the United States, with petroleum accounting for 90 percent of transportation fuels. Policymakers encounter a range of questions as they consider low-carbon fuel standards to reduce emissions, including total emissions released from production to use of a fuel or the potential consequences of a policy. Life-cycle assessment is an essential tool for addressing these questions. This report provides researchers and practitioners with a toolkit for applying life-cycle assessment to estimate greenhouse gas emissions, including identification of the best approach to use for a stated policy goal, how to reduce uncertainty and variability through verification and certification, and the core assumptions that can be applied to various fuel types. Policymakers should still use a tailored approach for each fuel type, given that petroleum-based ground, air, and marine transportation fuels necessitate different considerations than alternative fuels including biofuels, hydrogen, and electricity. Ultimately, life-cycle assessments should clearly document what assumptions and methods are used to ensure transparency.

The U.S. Department of Energy's Office of Environmental Management (DOE-EM) was established by Congress in 1989 to remediate waste and environmental contamination that have resulted from nuclear weapons production and related activities. It has expended almost $200 billion on cleanup and related activities since its establishment and completed cleanup at all but 15 of the more than 100 sites. At the request of Congress, the National Academies of Sciences, Engineering, and Medicine formed a committee to provide advice on enhancing the effectiveness and efficiency of DOE-EM cleanup activities, particularly with respect to project management, contracting, and oversight practices. These recommendations were provided in two reports. The first report, Review of Effectiveness and Efficiency of Defense Environmental Cleanup Activities of DOE's Office of Environmental Management: Report 1, considered overall project management practices, project management metrics and outcomes, and contract structures and performance measures. This second report focuses on specific DOE-EM sites to assess how effective the management of the numerous projects at the sites is contributing to the wider programmatic objectives of DOE-EM.

Radiation exposure at low doses (below 100 milligray) or low-dose rates (less than 5 milligray per hour) occurs in a wide range of medical, industrial, military, and commercial settings. The effects of exposure at these levels are not fully understood, but there are long-standing concerns that such exposure could negatively affect human health. Although cancer has been linked to low-dose radiation exposure for decades, there is increasing evidence that low-dose radiation exposure may also be associated with cardiovascular disease, neurological disorders, immune dysfunction, and cataracts. Recent advances in research, new tools, and a coordinated multidisciplinary research program could help fill knowledge gaps about the health impacts of low-dose radiation exposures. This report calls for the development of a U.S. research program to study how low doses of radiation affect cancer, cardiovascular disease, neurological disorders, and other disease risks. Research should also better define the impacts of radiation doses, dose rates, types of radiation, and exposure duration. The report estimates $100 million annually for the next 15 years would be required to conduct epidemiological and biological research, and to establish an infrastructure for research.

As of 2021, atmospheric carbon dioxide levels have reached historically unprecedented levels, higher than at any time in the past 800,000 years. Worldwide efforts to reduce emissions by creating a more efficient, carbon-free energy system may not be enough to stabilize the climate and avoid the worst impacts of climate change. Carbon dioxide removal (CDR) strategies, which remove and sequester carbon from the atmosphere, likely will be needed to meet global climate goals. The ocean, covering 70% of the Earth's surface, includes much of the global capacity for natural carbon sequestration; the ocean also holds great potential for uptake and longerterm sequestration of human-produced CO2. This report builds on previous work from the National Academies to assess what is currently known about the benefits, risks, and potential for responsible scale-up of six specific ocean-based CDR strategies as identified by the sponsor, ClimateWorks Foundation. It describes the research needed to advance understanding of those approaches and address knowledge gaps. The resulting research agenda is meant to provide an improved and unbiased knowledge base for the public, stakeholders, and policymakers to make informed decisions on the next steps for ocean CDR, as part of a larger climate mitigation strategy; it is not meant to lock in or advocate for any particular approach.

Human health risk assessments provide the basis for public health decision-making and chemical regulation in the United States. Three evidence streams generally support the development of human health risk assessments - epidemiology, toxicology, and mechanistic information. Epidemiologic studies are generally the preferred evidence stream for assessing causal relationships during hazard identification. However, the available studies may be limited in scope, subject to bias, or otherwise inadequate to inform causal inferences. In addition, there are challenges in assessing coherence, validity, and reliability during synthesis of individual epidemiological studies with different designs, which in turn affects conclusions on causation. Triangulation aims to address the challenge of synthesizing evidence from diverse studies with distinct sources of bias. Bias is a systematic error that leads to inaccurate study results. Tools for assessing risk of bias provide a structured list of questions for systematic consideration of different domains (such as confounding, selective reporting, and conflict of interest). These tools also provide a structured framework for identifying potential sources of bias and informing judgments on individual studies. The National Academies of Sciences, Engineering, and Medicine convened a workshop to understand and explore triangulation and opportunities to use the practice to enhance the EPA's human health assessments. The workshop was held virtually on May 9 and 11, 2022. This publication summarizes the key presentations and discussions conducted during the workshop.

The Bureau of Ocean Energy Management (BOEM) manages the energy and mineral resources on the outer continental shelf. BOEM's environmental program, by producing environmental studies and conducting environmental assessments, ensures that environmental protection is a critical element of BOEM's decision making. This report addresses BOEM's aspirations to conduct a first-in-class science program within their Environmental Studies Program (ESP). This report describes attributes identified by the committee of a first-in-class, use-inspired, management-oriented science program (in this case, BOEM's ESP and its connection to the broader BOEM environmental program). The report recommends that BOEM develop procedures and conduct regular evaluations to assess whether and how well its environmental program meets the attributes of a first-in-class program and identify areas for improvement. It also outlines a framework for conducting such an evaluation. The report contains guidance and examples drawn from a workshop series with BOEM's peer agencies and other science programs, as well as other information gathering efforts. The guidance contained in this report is offered to BOEM as a starting point for developing more detailed processes for evaluating and improving its program.

An estimated 8 million metric tons (MMT) of plastic waste enters the world's ocean each year - the equivalent of dumping a garbage truck of plastic waste into the ocean every minute. Plastic waste is now found in almost every marine habitat, from the ocean surface to deep sea sediments to the ocean's vast mid-water region, as well as the Great Lakes. This report responds to a request in the bipartisan Save Our Seas 2.0 Act for a scientific synthesis of the role of the United States both in contributing to and responding to global ocean plastic waste. The United States is a major producer of plastics and in 2016, generated more plastic waste by weight and per capita than any other nation. Although the U.S. solid waste management system is advanced, it is not sufficient to deter leakage into the environment. Reckoning with the U.S. Role in Global Ocean Plastic Waste calls for a national strategy by the end of 2022 to reduce the nation's contribution to global ocean plastic waste at every step - from production to its entry into the environment - including by substantially reducing U.S. solid waste generation. This report also recommends a nationally-coordinated and expanded monitoring system to track plastic pollution in order to understand the scales and sources of U.S. plastic waste, set reduction and management priorities, and measure progress.

Climate change, driven by increases in human-produced greenhouse gases and particles (collectively referred to as GHGs), is the most serious environmental issue facing society. The need to reduce GHGs has become urgent as heat waves, heavy rain events, and other impacts of climate change have become more frequent and severe. Since the Paris Agreement was adopted in 2015, more than 136 countries, accounting for about 80% of total global GHG emissions, have committed to achieving net-zero emissions by 2050. A growing number of cities, regional governments, and industries have also made pledges to reduce emissions. Providing decision makers with useful, accurate, and trusted GHG emissions information is a crucial part of this effort. This report examines existing and emerging approaches used to generate and evaluate GHG emissions information at global to local scales. The report develops a framework for evaluating GHG emissions information to support and guide policy makers about its use in decision making. The framework identifies six criteria or pillars that can be used to evaluate and improve GHG emissions information: usability and timeliness, information transparency, evaluation and validation, completeness, inclusivity, and communication. The report recommends creating a coordinated repository or clearinghouse to operationalize the six pillars, for example, by providing timely, transparent, traceable information; standardized data formats; and governance mechanisms that are coordinated, trusted, and inclusive of the global community.

Coeur d'Alene Lake in northern Idaho is an invaluable natural, recreational, and economic resource for communities in Idaho and eastern Washington. Starting in the late 1880s, mining in the Lake's watershed sent heavy metals and other mining wastes into the Lake, resulting in contamination of lake sediments with lead, cadmium, arsenic, and zinc that persists today. The watershed was designated a Superfund site and cleanup has been ongoing for 30 years. However, the Lake's environmental quality and cleanup is overseen by a Lake Management Plan, originally implemented by the Coeur d'Alene Tribe and the state of Idaho. A major focus of that plan is whether lakeshore development might promote low-oxygen (anoxic) conditions that could release toxic metals from lake sediments back into the water column. This report analyzes water quality data collected from the Lake and the watershed over the past 30 years. The analyses indicate that, although the Lake is still heavily contaminated, concentrations of metals in the major inputs to the Lake have declined, and there is no evidence that phosphorus concentrations have been increasing in the last decade or that low-oxygen events are becoming more common. However, the shorelines of the Lake, where exposure to metals or harmful algae is more likely, are not currently monitored. Protecting the water quality of Coeur d'Alene Lake will require that monitoring efforts be expanded to provide an early warning of deteriorating conditions, regular syntheses of data, and targeted studies—all coordinated among interest groups—followed by application of those results to managing the Lake.

Offshore wind energy development is poised to expand rapidly across the U.S. Outer Continental Shelf over the next decade, as part of a government-wide effort to develop more renewable sources of energy. Offshore wind energy planning and development has expanded along the U.S. Atlantic Coast, and to areas in the Gulf of Mexico and Pacific Coast. However, the maritime community has expressed concern that wind turbine generators, which are constructed predominantly of steel, can interfere with radar used in navigation. A particular concern is interference with marine vessel radar, which is a critical instrument for navigation, collision avoidance, and use in search and rescue missions, with secondary uses including activities like detecting reflectors on fishing nets or birds to indicate the presence of schools of fish. Previous studies of the impacts of wind turbine generators on radar relied on data from European wind farms - however, wind turbines located in or planned for the U.S. Outer Continental Shelf are larger, wider, and laid out in different configurations. Conducted at the request of the Bureau of Ocean Energy Management, this report identifies and characterizes the impacts of wind turbine generators on the efficacy of marine vessel radar on vessels operating within or near existing and planned offshore wind facilities on the U.S. Outer Continental Shelf. The report recommends pursing two courses of action to reduce impacts by: (1) filling knowledge gaps through data collection, modeling and analysis, and focused research on wind turbine generator characteristics; and (2) pursuing practicable options to reduce interference on marine vessel radar such as enhanced operator training, use of radar reflectors on small vessels, use of reference buoys, evaluation of radar mounting procedures, new radar designs, and the development of wind turbine generators with reduced radar signatures.

Radioactive Sources: Applications and Alternative Technologies assesses the status of medical, research, sterilization, and other commercial applications of radioactive sources and alternative (nonradioisotopic) technologies in the United States and internationally. Focusing on Category 1, 2, and 3 sources, this report reviews the current state of these sources by application and reviews the current state of existing technologies on the market or under development that are or could be used to replace radioisotopic technologies in those applications. Radioactive Sources will support existing and future activities under the National Nuclear Security Administration Office of Radiological Security program to reduce the use of high-risk radiological materials in commercial applications.

Systematic review - a scientific investigation that focuses on a specific question and uses explicit, prespecified scientific methods to identify, select, assess, and summarize the findings of similar but separate studies - has become the foundation for assessing evidence to be used for decision making in a variety of health contexts, including health care and public health. At the request of the Environmental Protection Agency (EPA), this publication reviews EPA's 2018 guidance document Application of Systematic Review in TSCA (Toxic Substances and Control Act) Risk Evaluations and associated materials to determine whether the process is comprehensive, workable, objective, and transparent.

The US Global Change Research Program (USGCRP) is a collection of 13 Federal entities charged by law to assist the United States and the world to understand, assess, predict, and respond to human-induced and natural processes of global change. Global Change Research Needs and Opportunities for 2022-2031 advises the USGCRP on how best to meet its mandate in light of climate change impacts happening today and projected into the future. This report identifies critical climate change risks, research needed to support decision-making relevant to managing these risks, and opportunities for the USGCRP's participating agencies and other partners to advance these research priorities over the next decade.

The U.S. Department of Energy (DOE) and its predecessor agencies have conducted activities to develop atomic energy for civilian and defense purposes since the initiation of the World War II Manhattan Project in 1942. These activities took place at large federal land reservations of hundreds of square miles involving industrial-scale operations, but also at many smaller federal and non-federal sites such as uranium mines, materials processing and manufacturing facilities. The nuclear weapons and energy production activities at these facilities produced large quantities of radioactive and hazardous wastes and resulted in widespread groundwater and soil contamination at these sites. DOE initiated a concerted effort to clean up these sites beginning in the 1980s. Many of these sites have been remediated and are in long-term caretaker status, closed or repurposed for other uses. Review of the Effectiveness and Efficiency of Defense Environmental Cleanup Activities of the Department of Energy's Office of Environmental Management: First Report provides background information on the sites currently assigned to the DOE's Office of Environmental Management that are undergoing cleanup; discusses current practices for management and oversight of the cleanups; offers findings and recommendations on such practices and how progress is measured against them; and considers the contracts under which the cleanups proceed and how these have been and can be structured to include incentives for improved cost and schedule performance.

During the past century, the Everglades, one of the world's treasured ecosystems, has been dramatically altered by drainage and water management infrastructure to improve flood management, urban water supply, and agricultural production. The remnants of the original Everglades now compete for water with urban and agricultural interests and are impaired by contaminated runoff from these two sectors. The Comprehensive Everglades Restoration Plan (CERP), a joint effort launched by the state and the federal government in 2000, seeks to reverse the decline of the ecosystem. The multibillion-dollar project was originally envisioned as a 30- to 40-year effort to achieve ecological restoration by reestablishing the natural hydrologic characteristics of the Everglades, where feasible, and to create a water system that serves the needs of both the natural and the human systems of South Florida. In establishing the CERP, Congress also requested that an independent scientific review be conducted on progress toward restoration with biennial reports. The National Academies'Committee on Independent Scientific Review of Everglades Restoration Progress has provided biennial reviews of restoration progress and advice on scientific and engineering issues that may impact progress since 2004. This eighth study of the series describes substantive accomplishments over the past 2 years and reviews developments in research, monitoring, and assessment that inform restoration decision making. Progress Toward Restoring the Everglades: The Eighth Biennial Review - 2020 also reviews the recently developed Combined Operational Plan, which is a prerequisite for CERP progress in the central Everglades, and examines issues facing the northern and southern estuaries, including priorities for science to support restoration decision making.

Climate change is creating impacts that are widespread and severe for individuals, communities, economies, and ecosystems around the world. While efforts to reduce emissions and adapt to climate impacts are the first line of defense, researchers are exploring other options to reduce warming. Solar geoengineering strategies are designed to cool Earth either by adding small reflective particles to the upper atmosphere, by increasing reflective cloud cover in the lower atmosphere, or by thinning high-altitude clouds that can absorb heat. While such strategies have the potential to reduce global temperatures, they could also introduce an array of unknown or negative consequences. This report concludes that a strategic investment in research is needed to enhance policymakers'understanding of climate response options. The United States should develop a transdisciplinary research program, in collaboration with other nations, to advance understanding of solar geoengineering's technical feasibility and effectiveness, possible impacts on society and the environment, and social dimensions such as public perceptions, political and economic dynamics, and ethical and equity considerations. The program should operate under robust research governance that includes such elements as a research code of conduct, a public registry for research, permitting systems for outdoor experiments, guidance on intellectual property, and inclusive public and stakeholder engagement processes.

Biokinetic modeling provides a mathematical technique for estimating absorption, distribution, metabolism, and excretion of chemicals, including particles and metals, in humans. Such models can be used to relate the amount of lead external exposure to the amount of lead found in the blood and other tissues at different points in time. At the request of the Department of Defense (DoD), Review of the Department of Defense Biokinetic Modeling Approach in Support of Establishing an Airborne Lead Exposure Limit evaluates whether the model used by DoD to derive airborne lead concentrations from blood lead levels is appropriate. This report also considers whether DoD's modifications to the model are appropriately justified, and whether the assumptions in and inputs to the model are reasonable.

New York City's municipal water supply system provides about 1 billion gallons of drinking water a day to over 8.5 million people in New York City and about 1 million people living in nearby Westchester, Putnam, Ulster, and Orange counties. The combined water supply system includes 19 reservoirs and three controlled lakes with a total storage capacity of approximately 580 billion gallons. The city's Watershed Protection Program is intended to maintain and enhance the high quality of these surface water sources. Review of the New York City Watershed Protection Program assesses the efficacy and future of New York City's watershed management activities. The report identifies program areas that may require future change or action, including continued efforts to address turbidity and responding to changes in reservoir water quality as a result of climate change.

Whether the result of an oil well blowout, vessel collision or grounding, leaking pipeline, or other incident at sea, each marine oil spill will present unique circumstances and challenges. The oil type and properties, location, time of year, duration of spill, water depth, environmental conditions, affected biomes, potential human community impact, and available resources may vary significantly. Also, each spill may be governed by policy guidelines, such as those set forth in the National Response Plan, Regional Response Plans, or Area Contingency Plans. To respond effectively to the specific conditions presented during an oil spill, spill responders have used a variety of response options—including mechanical recovery of oil using skimmers and booms, in situ burning of oil, monitored natural attenuation of oil, and dispersion of oil by chemical dispersants. Because each response method has advantages and disadvantages, it is important to understand specific scenarios where a net benefit may be achieved by using a particular tool or combination of tools. This report builds on two previous National Research Council reports on dispersant use to provide a current understanding of the state of science and to inform future marine oil spill response operations. The response to the 2010 Deepwater Horizon spill included an unprecedented use of dispersants via both surface application and subsea injection. The magnitude of the spill stimulated interest and funding for research on oil spill response, and dispersant use in particular. This study assesses the effects and efficacy of dispersants as an oil spill response tool and evaluates trade-offs associated with dispersant use.

During the 20th century, the city of Los Angeles diverted surface water flowing into Owens Lake for water supply, transforming the large, closed-basin, saline lake into a small brine pool surrounded by dry playa. Under high winds, the exposed lakebed produced large amounts of airborne dust, resulting in the highest concentrations of airborne particulate matter with an aerodynamic diameter of 10 micrometers or less (PM10) in the United States. Since 2000, the Los Angeles Department of Water and Power, at the direction of the Great Basin Unified Air Pollution Control District, has been constructing and implementing dust control measures on the dry lakebed, with the objective of meeting the U.S. Environmental Protection Agency National Ambient Air Quality Standards for PM10 and the PM10 standards set by the state of California. Many of the dust control measures used at Owens Lake require large amounts of water, energy, and maintenance to sustain their performance. Effectiveness and Impacts of Dust Control Measures for Owens Lake evaluates the effectiveness of alternative solutions for their degree of PM10 reduction and the extent that they reduce use of water in controlling dust emissions. This report considers the associated energy and environmental and economic impacts of these proposed measures and assesses their durability and reliability.

Exposures at low doses of radiation, generally taken to mean doses below 100 millisieverts, are of primary interest for setting standards for protecting individuals against the adverse effects of ionizing radiation. However, there are considerable uncertainties associated with current best estimates of risks and gaps in knowledge on critical scientific issues that relate to low dose radiation. The Nuclear and Radiation Studies Board of the National Academies hosted the symposium on The Future of Low Dose Radiation Research in the United States on May 8 and 9, 2019. The goal of the symposium was to provide an open forum for a national discussion on the need for a long-term strategy to guide a low dose radiation research program in the United States. The symposium featured presentations on low dose radiation programs around the world, panel discussions with representatives from governmental and nongovernmental organizations about the need for a low dose radiation research program, reviews of low dose radiation research in epidemiology and radiation biology including new directions, and lessons to be learned from setting up large research programs in non-radiation research fields. This publication summarizes the presentation and discussion of the symposium.

The Integrated Risk Information System (IRIS) is a program within the US Environmental Protection Agency (EPA) that is responsible for developing toxicologic assessments of environmental contaminants. An IRIS assessment contains hazard identifications and dose-response assessments of various chemicals related to cancer and noncancer outcomes. Although the program was created to increase consistency among toxicologic assessments within the agency, federal, state, and international agencies and other organizations have come to rely on IRIS assessments for setting regulatory standards, establishing exposure guidelines, and estimating risks to exposed populations. The EPA has been working on its IRIS assessment of inorganic arsenic (iAs) for many years, and recently released its plans for completing it in the Updated Problem Formulation and Protocol for the Inorganic Arsenic IRIS Assessment. Much of the update was made in response to recommendations in a 2013 report made by the National Academies of Sciences, Engineering, and Medicine. The National Academies recently convened another evaluation of whether the various elements of the IRIS iAs assessment plan are appropriate to synthesize the scientific evidence and quantitate estimates of iAs toxicity. Review of EPA's IRIS Assessment Plan for Inorganic Arsenic explores the EPA's approach to prioritizing health outcomes, EPA's systematic review methods, EPA's consideration of potential health effects from early life exposures, mode-of-action information to inform dose-response analyses, and various approaches to investigate dose-response relationships.

Industrial stormwater is derived from precipitation and/or runoff that comes in contact with industrial manufacturing, processing, storage, or material overburden and then runs offsite and enters drainage systems or receiving waters. In 1987, Congress significantly expanded the National Pollutant Discharge Elimination System (NPDES) program through amendments to the Clean Water Act to include industrial stormwater runoff conveyed through outfalls directly to receiving waters or indirectly through municipal separate storm sewer systems. The added regulation of stormwater in the NPDES program has been challenging. Stormwater is produced throughout a developed landscape, and its production and delivery are episodic. In 2009, the National Research Council released a comprehensive report on the Environmental Protection Agency's Stormwater Program that covered all sectors of the program. This study builds on that report, with a focus on industrial stormwater monitoring and management.

In the 1970s, flame retardants began to be added to synthetic materials to meet strict flammability standards. Over the years, diverse flame retardants have been manufactured and used in various products. Some flame retardants have migrated out of the products, and this has led to widespread human exposure and environmental contamination. There also is mounting evidence that many flame retardants are associated with adverse human health effects. As a result, some flame retardants have been banned, restricted, or voluntarily phased out of production and use. This publication develops a scientifically based scoping plan to assess additive, nonpolymeric organohalogen flame retardants as a class for potential chronic health hazards under the Federal Hazardous Substances Act, including cancer, birth defects, and gene mutations.

Trichloroethylene (TCE) is a solvent that is used as a degreasing agent, a chemical intermediate in refrigerant manufacture, and a component of spot removers and adhesives. It is produced in mass quantities but creates dangerous vapors and is an environmental contaminant at many industrial and government facilities, including facilities run by the U.S. Department of Defense (DoD). It is important to determine the safe occupational exposure level (OEL) for the solvent in order to protect the health of workers who are exposed to its vapors. However, there are concerns that the current occupational standards insufficiently protect workers from these health threats. Review of DOD's Approach to Deriving an Occupational Exposure Level for Trichloroethylene makes recommendations to improve the DoD's approach to developing an OEL for TCE, strengthen transparency of the process, and improve confidence in the final OEL value. This report reviews the DoD's approach using a literature review, evidence synthesis based on weight of evidence [WOE], point-of-departure derivation, physiologically based pharmacokinetic modeling, extrapolation tools, and explores other elements of the process of deriving an OEL for TCE. It examines scientific approaches to developing exposure values and cancer risk levels, defining the scope of the problem, and improving hazard identification.

The 1980 eruption of Mount St. Helens in southwest Washington State radically changed the physical and socio-economic landscapes of the region. The eruption destroyed the summit of the volcano, sending large amounts of debris into the North Fork Toutle River, and blocking the sole means of drainage from Spirit Lake 4 miles north of Mount St. Helens. As a result of the blockage, rising lake levels could cause failure of the debris blockage, putting the downstream population of approximately 50,000 at risk of catastrophic flooding and mud flows. Further, continued transport of sediment to the river from volcanic debris deposits surrounding the mountain reduces the flood carrying capacity of downstream river channels and leaves the population vulnerable to chronic flooding. The legacy of the 1980 eruption and the prospect of future volcanic, seismic, and flood events mean that risk management in the Spirit Lake Toutle River system will be challenging for decades to come. This report offers a decision framework to support the long-term management of risks related to the Spirit Lake and Toutle River system in light of the different regional economic, cultural, and social priorities, and the respective roles of federal, tribal, state, and local authorities, as well as other entities and groups in the region. It also considers the history and adequacy of characterization, monitoring, and management associated with the Spirit Lake debris blockage and outflow tunnel, other efforts to control transport of water and sediment from the 1980 and later eruptions, and suggests additional information needed to support implementation of the recommended decision framework.

Over the past several years, the US Environmental Protection Agency (EPA) has been transforming the procedures of its Integrated Risk Information System (IRIS), a program that produces hazard and dose?response assessments of environmental chemicals and derives toxicity values that can be used to estimate risks posed by exposures to them. The transformation was initiated after suggestions for program reforms were provided in a 2011 report from the National Academies of Sciences, Engineering, and Medicine that reviewed a draft IRIS assessment of formaldehyde. In 2014, the National Academies released a report that reviewed the IRIS program and evaluated the changes implemented in it since the 2011 report. Since 2014, new leadership of EPA's National Center for Environmental Assessment (NCEA) and IRIS program has instituted even more substantive changes in the IRIS program in response to the recommendations in the 2014 report. Progress Toward Transforming the Integrated Risk Information System Program: A 2018 Evaluation reviews the EPA's progress toward addressing the past recommendations from the National Academies.

Climate change poses many challenges that affect society and the natural world. With these challenges, however, come opportunities to respond. By taking steps to adapt to and mitigate climate change, the risks to society and the impacts of continued climate change can be lessened. The National Climate Assessment, coordinated by the U.S. Global Change Research Program, is a mandated report intended to inform response decisions. Required to be developed every four years, these reports provide the most comprehensive and up-to-date evaluation of climate change impacts available for the United States, making them a unique and important climate change document. The draft Fourth National Climate Assessment (NCA4) report reviewed here addresses a wide range of topics of high importance to the United States and society more broadly, extending from human health and community well-being, to the built environment, to businesses and economies, to ecosystems and natural resources. This report evaluates the draft NCA4 to determine if it meets the requirements of the federal mandate, whether it provides accurate information grounded in the scientific literature, and whether it effectively communicates climate science, impacts, and responses for general audiences including the public, decision makers, and other stakeholders.

A great number of diverse microorganisms inhabit the human body and are collectively referred to as the human microbiome. Until recently, the role of the human microbiome in maintaining human health was not fully appreciated. Today, however, research is beginning to elucidate associations between perturbations in the human microbiome and human disease and the factors that might be responsible for the perturbations. Studies have indicated that the human microbiome could be affected by environmental chemicals or could modulate exposure to environmental chemicals. Environmental Chemicals, the Human Microbiome, and Health Risk presents a research strategy to improve our understanding of the interactions between environmental chemicals and the human microbiome and the implications of those interactions for human health risk. This report identifies barriers to such research and opportunities for collaboration, highlights key aspects of the human microbiome and its relation to health, describes potential interactions between environmental chemicals and the human microbiome, reviews the risk-assessment framework and reasons for incorporating chemical–microbiome interactions.

The U.S. Gulf Coast provides a valuable setting to study deeply connected natural and human interactions and feedbacks that have led to a complex, interconnected coastal system. The physical landscape in the region has changed significantly due to broad-scale, long-term processes such as coastal subsidence and river sediment deposition as well as short-term episodic events such as hurricanes. Modifications from human activities, including building levees and canals and constructing buildings and roads, have left their own imprint on the natural landscape. This coupled natural-human coastal system and the individual aspects within it (physical, ecological, and human) are under increased pressure from accelerating environmental stressors such as sea level rise, intensifying hurricanes, and continued population increase with its accompanying coastal development. Promoting the resilience and maintaining the habitability of the Gulf Coast into the future will need improved understanding of the coupled natural-human coastal system, as well as effective sharing of this understanding in support of decision-making and policies. Understanding the Long-term Evolution of the Coupled Natural-Human Coastal System presents a research agenda meant to enable a better understanding of the multiple and interconnected factors that influence long-term processes along the Gulf Coast. This report identifies scientific and technical gaps in understanding the interactions and feedbacks between human and natural processes, defines essential components of a research and development program in response to the identified gaps, and develops priorities for critical areas of research.

The U.S. Environmental Protection Agency (EPA) has a mission and regulatory responsibility to protect human health and the environment. EPA's pursuit of that goal includes a variety of research activities involving human subjects, such as epidemiologic studies and surveys. Those research activities also involve studies of individuals who volunteer to be exposed to air pollutants intentionally in controlled laboratory settings so that measurements can be made of transient and reversible biomarker or physiologic responses to those exposures that can indicate pathways of toxicity and mechanisms of air-pollution responses. The results of those controlled human inhalation exposure (CHIE) studies, also referred to as human clinical studies or human challenge studies, are used to inform policy decisions and help establish or revise standards to protect public health and improve air quality. Controlled Human Inhalation-Exposure Studies at EPA addresses scientific issues and provides guidance on the conduct of CHIE studies. This report assesses the utility of CHIE studies to inform and reduce uncertainties in setting air-pollution standards to protect public health and assess whether continuation of such studies is warranted. It also evaluates the potential health risks to test subjects who participated in recent studies of air pollutants at EPA's clinical research facility.

The U.S. Global Change Research Program (USGCRP) was established in 1990 to'assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change.'1 A key responsibility for the program is to conduct National Climate Assessments (NCAs) every 4 years.2 These assessments are intended to inform the nation about'observed changes in climate, the current status of the climate, and anticipated trends for the future.'The USGCRP hopes that government entities from federal agencies to small municipalities, citizens, communities, and businesses will rely on these assessments of climate- related risks for planning and decision-making. The third NCA (NCA3) was published in 2014 and work on the fourth is beginning. The USGCRP asked the Board on Environmental Change and Society of the National Academies of Sciences, Engineering, and Medicine to conduct a workshop to explore ways to frame the NCA4 and subsequent NCA reports in terms of risks to society. The workshop was intended to collect experienced views on how to characterize and communicate information about climate-related hazards, risks, and opportunities that will support decision makers in their efforts to reduce greenhouse gas emissions, reduce vulnerability to likely changes in climate, and increase resilience to those changes. Characterizing Risk in Climate Change Assessments summarizes the presentations and discussions from the workshop.

Over the last decade, several large-scale United States and international programs have been initiated to incorporate advances in molecular and cellular biology, -omics technologies, analytical methods, bioinformatics, and computational tools and methods into the field of toxicology. Similar efforts are being pursued in the field of exposure science with the goals of obtaining more accurate and complete exposure data on individuals and populations for thousands of chemicals over the lifespan; predicting exposures from use data and chemical-property information; and translating exposures between test systems and humans. Using 21st Century Science to Improve Risk-Related Evaluations makes recommendations for integrating new scientific approaches into risk-based evaluations. This study considers the scientific advances that have occurred following the publication of the NRC reports Toxicity Testing in the 21st Century: A Vision and a Strategy and Exposure Science in the 21st Century: A Vision and a Strategy. Given the various ongoing lines of investigation and new data streams that have emerged, this publication proposes how best to integrate and use the emerging results in evaluating chemical risk. Using 21st Century Science to Improve Risk-Related Evaluations considers whether a new paradigm is needed for data validation, how to integrate the divergent data streams, how uncertainty might need to be characterized, and how best to communicate the new approaches so that they are understandable to various stakeholders.

The Superfund program of the US Environmental Protection Agency (EPA) was created in the 1980s to address human-health and environmental risks posed by abandoned or uncontrolled hazardous-waste sites. Identification of Superfund sites and their remediation is an expensive multistep process. As part of this process, EPA attempts to identify parties that are responsible for the contamination and thus financially responsible for remediation. Identification of potentially responsible parties is complicated because Superfund sites can have a long history of use and involve contaminants that can have many sources. Such is often the case for mining sites that involve metal contamination; metals occur naturally in the environment, they can be contaminants in the wastes generated at or released from the sites, and they can be used in consumer products, which can degrade and release the metals back to the environment. This report examines the extent to which various sources contribute to environmental lead contamination at Superfund sites that are near lead-mining areas and focuses on sources that contribute to lead contamination at sites near the Southeast Missouri Lead Mining District. It recommends potential improvements in approaches used for assessing sources of lead contamination at or near Superfund sites.

The Department of Energy's Office of Environmental Management (DOE) is responsible for the safe cleanup of sites used for nuclear weapons development and government-sponsored nuclear energy research. Low-level radioactive waste (LLW) is the most volumetrically significant waste stream generated by the DOE cleanup program. LLW is also generated through commercial activities such as nuclear power plant operations and medical treatments. The laws and regulations related to the disposal of LLW in the United States have evolved over time and across agencies and states, resulting in a complex regulatory structure. DOE asked the National Academies of Sciences, Engineering, and Medicine to organize a workshop to discuss approaches for the management and disposition of LLW. Participants explored the key physical, chemical, and radiological characteristics of low-level waste that govern its safe and secure management and disposal in aggregate and in individual waste streams, and how key characteristics of low level waste are incorporated into standards, orders, and regulations that govern the management and disposal of LLW in the United States and in other major waste-producing countries. This publication summarizes the presentations and discussions from the workshop.