D. Warner North

A review of whole animal bioassays of the carcinogenic potential of naphthalene

This report provides a summary of deliberations conducted under the charge for members of Module A participating in the Naphthalene State-of-the-Science Symposium (NS3), Monterey, CA, October 9-12, 2006. Whole animal bioassays have been performed by the National Toxicology Program in mice and rats to ascertain the carcinogenic potential of naphthalene by inhalation exposure. A statistically significant increased incidence of pulmonary alveolar/bronchiolar adenoma (a benign lesion), was observed among female mice; an observed increase among the males did not reach statistical significance. No nasal tumors were observed in either sex. A tumorigenic response was observed in both sexes of rats, in males an increased incidence of nasal respiratory epithelium adenoma (a benign rather than malignant lesion) and in females, olfactory epithelial neuroblastoma. Interpretations of these studies vary. On the one hand, evidence of extensive non-neoplastic response in both sexes of both species indicates cytotoxicity occurred at all doses, and strongly suggests that cytotoxicity played a significant role in the tumor responses observed in the target tissues. On the other hand, olfactory epithelial neuroblastoma has rarely been observed in NTP bioassays. This review seeks to develop a consensus understanding of the scientific evidence provided by these studies, taking into account that they have been used as the basis for quantitative human cancer risk assessment, and suggests scientific studies that, if performed, could resolve scientific uncertainties.

A methodology for analyzing emission control strategies

Abstract Alternative strategies for controlling sulfur oxide emissions from representative coal fired electric power plants are evaluated both in terms of their economic and environmental impacts. A framework is provided for converting environmental impacts to human health, ecological, aesthetic, and material damage costs borne by society. A comparison of these costs to the costs of pollution control provides the basis for choice among available strategies. Existing uncertainties in health effects and SO2 atmospheric transport and conversion are explicitly represented. These uncertainties are shown to be crucial to the decision among control strategies. Computations show the resolution of these uncertainties to be worth hundreds of millions of dollars per year.

A Perspective on Nuclear Waste

The management of spent nuclear fuel and high-level nuclear waste has the deserved reputation as one of the most intractable policy issues facing the United States and other nations using nuclear reactors for electric power generation. This paper presents the authors perspective on this complex issue, based on a decade of service with the Nuclear Waste Technical Review Board and Board on Radioactive Waste Management of the National Research Council.

Principles for Conduct of Pest Risk Analyses: Report of an Expert Workshop

The North American Free Trade Agreement (NAFTA) and the General Agreement on Tariffs and Trade (GATT) have focused attention on risk assessment of potential insect, weed, and animal pests and diseases of livestock. These risks have traditionally been addressed through quarantine protocols ranging from limits on the geographical areas from which a product may originate, postharvest disinfestation procedures like fumigation, and inspections at points of export and import, to outright bans. To ensure that plant and animal protection measures are not used as nontariff trade barriers, GATT and NAFTA require pest risk analysis (PRA) to support quarantine decisions. The increased emphasis on PRA has spurred multiple efforts at the national and international level to design frameworks for the conduct of these analyses. As approaches to pest risk analysis proliferate, and the importance of the analyses grows, concerns have arisen about the scientific and technical conduct of pest risk analysis. In January of 1997, the Harvard Center for Risk Analysis (HCRA) held an invitation-only workshop in Washington, D.C. to bring experts in risk analysis and pest characterization together to develop general principles for pest risk analysis. Workshop participants examined current frameworks for PRA, discussed strengths and weaknesses of the approaches, and formulated principles, based on years of experience with risk analysis in other setting and knowledge of the issues specific to analysis of pests. The principles developed highlight the both the similarities of pest risk analysis to other forms of risk analysis, and its unique attributes.

The naphthalene state of the science symposium: objectives, organization, structure, and charge.

This report provides a summary of the objectives, organization, structure and charge for the naphthalene state of the science symposium (NS(3)), Monterey, CA, October 9-12, 2006. A 1-day preliminary conference was held followed by a 3-day state of the science symposium covering four topics judged by the Planning Committee to be crucial for developing valid and reliable scientific estimates of low-dose human cancer risk from naphthalene. The Planning Committee reviewed the relevant scientific literature to identify singularly knowledgeable researchers and a pool of scientists qualified to serve as expert panelists. In two cases, independent scientists were commissioned to develop comprehensive reviews of the relevant science in a specific area for which no leading researcher could be identified. Researchers and expert panelists alike were screened for conflicts of interest. All policy issues related to risk assessment practices and risk management were scrupulously excluded. NS(3) was novel in several ways and provides an innovative model for the effective use of peer review to identify scientific uncertainties and propose research strategies for reducing or eliminating them prior to the conduct of risk assessment.

Whither risk assessment: new challenges and opportunities a third of a century after the Red Book

Six multi-decade-long members of SRA reflect on the 1983 Red Book in order to examine the evolving relationship between risk assessment and risk management; the diffusion of risk assessment practice to risk areas such as homeland security and transportation; the quality of chemical risk databases; challenges from other groups to elements at the core of risk assessment practice; and our collective efforts to communicate risk assessment to a diverse set of critical groups that do not understand risk, risk assessment, or many other risk-related issues. The authors reflect on the 10 recommendations in the Red Book and present several pressing challenges for risk assessment practitioners.

Comment on Influence Diagram Retrospective

Influence diagrams were first used in 1973 as a way to model political conflicts in the Persian Gulf and measure the value of information collected by the Defense Intelligence Agency. The number of scenarios for events in the region was too large to be represented as a conventional decision tree model. Influence diagrams were initially conceived as a way to create smaller, coalesced decision trees that required fewer probability assessments. However we found that they also facilitated communication between analysts, experts, and policy makers. Influence diagrams later became the basis for new ways of solving decision models.

Can Sisyphus Succeed? Getting U.S. High-Level Nuclear Waste into a Geological Repository

The U.S. government has the obligation of managing the high-level radioactive waste from its defense activities and also, under existing law, from civilian nuclear power generation. This obligation is not being met. The January 2012 Final Report from the Blue Ribbon Commission on Americas Nuclear Future provides commendable guidance but little that is new. The author, who served on the federal Nuclear Waste Technical Review Board from 1989 to 1994 and subsequently on the Board on Radioactive Waste Management of the National Research Council from 1994 to 1999, provides a perspective both on the Commissions recommendations and a potential path toward progress in meeting the federal obligation. By analogy to Sisyphus of Greek mythology, our nation needs to find a way to roll the rock to the top of the hill and have it stay there, rather than continuing to roll back down again.

Space Weather: Introducing a Survey Paper and a Recent Executive Order

As an Area Editor for Risk Analysis, it is my pleasure and privilege to manage the review of submitted articles. It is gratifying to find an excellent survey article on a risk that is relatively unfamiliar to many of our readers, and to bring it though our editorial process to publication. This is the case with our lead article for this February issue, “The Economic Impact of Space Weather – Where Do We Stand?” “Space weather” involves charged particles and radiation from the sun and sources outside the solar system reaching the Earth or spacecraft. Interaction of a massive discharge of charged particles from the sun with the Earth’s magnetic field is often referred to as a “geomagnetic storm.” It can induce electric currents that overload and damage electrical and communications infrastructure, especially the electrical grid (high-voltage lines and transformers) plus communication and navigation satellites. The “Carrington event” in 1859(1,2) induced electric currents strong enough to melt copper telegraph wires, and produced auroras seen as far south as Central America and Columbia. Analyses of sun-like stars using data from National Aeronautics and Space Administration (NASA)’s Kepler telescope suggest that events of 10 times the strength of the Carrington event, far more intense than any experienced in the 20th and 21st centuries, may occur on millennial timescales. Could such intense space weather events burn out critical components, so that the electricity grids on which our technological civilization depends would be disabled—and over how large an area and for how long a time? The sources summarized in the lead article give estimates of probabilities and a diversity of projected impacts. A Carrington-eventlevel storm happening today could have a total economic cost in the range of trillions of dollars, as the consequence of very prolonged electric power grid outages due primarily to transformer replacement times of many months. Other projections suggest damage in the hundreds-of-billions range within a five-year period following the event. Some experts have asserted that newer transformers are more resilient, and that voltage instability will be the most likely impact from a severe geomagnetic storm, with resulting grid outages lasting hours to days rather than months. Impacts on satellites have been estimated as high as

Probability Theory and Consistent Reasoning

70 billion. Details and a large number of references are provided in the article. Potential economic consequences of such high magnitude should motivate further investigation, especially when they are coupled with the reality that only about a 150 years of direct observational data are available as a basis for assessing space weather event probabilities. Accordingly, investigation and planning efforts by the federal government have recently been initiated. President Barack Obama issued an Executive Order, “Coordinating Efforts to Prepare the Nation for Space Weather Events,” on October 13, 2016.(3) This order instructs the Director of the Office of Science and Technology Policy, in consultation with the Assistant to the President for Homeland Security and Counterterrorism and the Director of the Office of Management and Budget, to “coordinate the development and implementation of Federal Government activities to prepare the Nation for space weather events,” including soliciting recommendations from the National Science and Technology Council and encouraging stakeholder engagement. Sections 4 and 5 of the Order give specific instructions to the Secretaries of Defense, Interior, Commerce, Energy, Homeland Security, State, and Transportation, the Administrator of the NASA, and the Director of the National