The potential of various dielectric gases to cause cellular death was assayed in an in vitro cell culture system using Chinese hamster V79 (lung) cells. Exposures were carried out in small tubes which were constantly rotated, so that cells were exposed to the gas with only a thin layer of culture liquid interposed. Results indicated that SF6 was essentially without cytotoxic effect, but after discharge of 16 kJ total spark energy in 60 cm3 of SF6, such samples of freshly sparked gas were quite cytotoxic (˜ 60% and 90% cell death following 1 and 4 hr exposures, respectively). The toxicity of these sparked samples was observed within 15 min of exposure of the cells (˜60% cell killing), and the degree of cell death increased with time of exposure, at least up to 2 hrs. The cytotoxicity of sparked SF6 samples decreased with time of storage, so that after 4 wks, such samples were only minimally cytotoxic. Increasing spark energy produced samples with increased cytotoxic activity (1.6 kJ caused ˜70% cell death after a 4 hr exposure, while 160 kJ of spark energy resulted in total cytotoxicity, after 1 hr).

This report documents the analysis of the biomass fuel cycle, in which biomass is combusted to produce electricity. The major objectives of this study were: (1) to implement the methodological concepts which were developed in the Background Document (ORNL/RFF 1992) as a means of estimating the external costs and benefits of fuel cycles, and by so doing, to demonstrate their application to the biomass fuel cycle; (2) to develop, given the time and resources, a range of estimates of marginal (i.e., the additional or incremental) damages and benefits associated with selected impact-pathways from a new wood-fired power plant, using a representative benchmark technology, at two reference sites in the US; and (3) to assess the state of the information available to support energy decision making and the estimation of externalities, and by so doing, to assist in identifying gaps in knowledge and in setting future research agendas. The demonstration of methods, modeling procedures, and use of scientific information was the most important objective of this study. It provides an illustrative example for those who will, in the future, undertake studies of actual energy options and sites. As in most studies, a more comprehensive analysis could have been completed had budget constraints not been as severe. Particularly affected were the air and water transport modeling, estimation of ecological impacts, and economic valuation. However, the most important objective of the study was to demonstrate methods, as a detailed example for future studies. Thus, having severe budget constraints was appropriate from the standpoint that these studies could also face similar constraints. Consequently, an important result of this study is an indication of what can be done in such studies, rather than the specific numerical estimates themselves.

Development efforts since the late 1970s have resulted in a generalized method for ranking health hazards. This method provides the basis for a wide range of applications where decisions are needed for allocating resources on the basis of health risk considerations. It has been used for more than a decade to solve real problems, and it is supported by 23 publications in the open literature. The diversity of this generalized methodology allows us to provide support in a great number of problem areas. we give four examples in this manuscript: the relative toxicities of petroleum mixtures; a method to derive Emergency Response Planning Guides; an estimate of the possible carcinogenic potency of tungsten, an alternative material to depleted uranium for heavy armor penetrators; and an approach to low dose extrapolation. Our experience suggests that many more applications of the original concept and variations on it can be of utility in military situations. Some potentially fruitful areas may be in the: development of a health-risk-ranking system for alternative solutions to manufacturing, waste management, and remediation; provision of a basis for identifying levels of hazardous agents which are below health concerns, or which should be of concern; development of a framework for evaluating chemicals and radioactive materials on the same basis, and in the development of a battery of in vitro bioassays which could take the place of long-term whole animal tests.

that the price of electricity does not reflect. How do you estimate the externalities of fuel cycles? Our previous report describes a methodological framework for doing so--called the damage function approach. This approach consists of five steps: (1) characterize the most important fuel cycle activities and their discharges, where importance is based on the expected magnitude of their externalities, (2) estimate the changes in pollutant concentrations or other effects of those activities, by modeling the dispersion and transformation of each pollutant, (3) calculate the impacts on ecosystems, human health, and any other resources of value (such as man-made structures), (4) translate the estimates of impacts into economic terms to estimate damages and benefits, and (5) assess the extent to which these damages and benefits are externalities, not reflected in the price of electricity. Each step requires a different set of equations, models and analysis. Analysts generally believe this to be the best approach for estimating externalities, but it has hardly been used! The reason is that it requires considerable analysis and calculation, and to this point in time, the necessary equations and models have not been assembled. Equally important, the process of identifying and estimating externalities leads to a number of complex issues that also have not been fully addressed. This document contains two types of papers that seek to fill part of this void. Some of the papers describe analytical methods that can be applied to one of the five steps of the damage function approach. The other papers discuss some of the complex issues that arise in trying to estimate externalities. This report, the second in a series of eight reports, is part of a joint study by the U.S. Department of Energy (DOE) and the Commission of the European Communities (EC)* on the externalities of fuel cycles. Most of the papers in this report were originally written as working papers during the initial phases of this study. The papers provide descriptions of the (non-radiological) atmospheric dispersion modeling that the study uses; reviews much of the relevant literature on ecological and health effects, and on the economic valuation of those impacts; contains several papers on some of the more complex and contentious issues in estimating externalities; and describes a method for depicting the quality of scientific information that a study uses. The analytical methods and issues that this report discusses generally pertain to more than one of the fuel cycles, though not necessarily to all of them. The report is divided into six parts, each one focusing on a different subject area.

that the price of electricity does not reflect. How do you estimate the externalities of fuel cycles? Our previous report describes a methodological framework for doing so--called the damage function approach. This approach consists of five steps: (1) characterize the most important fuel cycle activities and their discharges, where importance is based on the expected magnitude of their externalities, (2) estimate the changes in pollutant concentrations or other effects of those activities, by modeling the dispersion and transformation of each pollutant, (3) calculate the impacts on ecosystems, human health, and any other resources of value (such as man-made structures), (4) translate the estimates of impacts into economic terms to estimate damages and benefits, and (5) assess the extent to which these damages and benefits are externalities, not reflected in the price of electricity. Each step requires a different set of equations, models and analysis. Analysts generally believe this to be the best approach for estimating externalities, but it has hardly been used! The reason is that it requires considerable analysis and calculation, and to this point in time, the necessary equations and models have not been assembled. Equally important, the process of identifying and estimating externalities leads to a number of complex issues that also have not been fully addressed. This document contains two types of papers that seek to fill part of this void. Some of the papers describe analytical methods that can be applied to one of the five steps of the damage function approach. The other papers discuss some of the complex issues that arise in trying to estimate externalities. This report, the second in a series of eight reports, is part of a joint study by the U.S. Department of Energy (DOE) and the Commission of the European Communities (EC)* on the externalities of fuel cycles. Most of the papers in this report were originally written as working papers during the initial phases of this study. The papers provide descriptions of the (non-radiological) atmospheric dispersion modeling that the study uses; reviews much of the relevant literature on ecological and health effects, and on the economic valuation of those impacts; contains several papers on some of the more complex and contentious issues in estimating externalities; and describes a method for depicting the quality of scientific information that a study uses. The analytical methods and issues that this report discusses generally pertain to more than one of the fuel cycles, though not necessarily to all of them. The report is divided into six parts, each one focusing on a different subject area.

The activities that produce electric power typically range from extracting and transporting a fuel, to its conversion into electric power, and finally to the disposition of residual by-products. This chain of activities is called a fuel cycle. A fuel cycle has emissions and other effects that result in unintended consequences. When these consequences affect third parties (i.e., those other than the producers and consumers of the fuel-cycle activity) in a way that is not reflected in the price of electricity, they are termed ''hidden'' social costs or externalities. They are the economic value of environmental, health and any other impacts, that the price of electricity does not reflect. How do you estimate the externalities of fuel cycles? Our previous report describes a methodological framework for doing so--called the damage function approach. This approach consists of five steps: (1) characterize the most important fuel cycle activities and their discharges, where importance is based on the expected magnitude of their externalities, (2) estimate the changes in pollutant concentrations or other effects of those activities, by modeling the dispersion and transformation of each pollutant, (3) calculate the impacts on ecosystems, human health, and any other resources of value (such as man-made structures), (4) translate the estimates of impacts into economic terms to estimate damages and benefits, and (5) assess the extent to which these damages and benefits are externalities, not reflected in the price of electricity. Each step requires a different set of equations, models and analysis. Analysts generally believe this to be the best approach for estimating externalities, but it has hardly been used! The reason is that it requires considerable analysis and calculation, and to this point in time, the necessary equations and models have not been assembled. Equally important, the process of identifying and estimating externalities leads to a number of complex issues that also have not been fully addressed. This document contains two types of papers that seek to fill part of this void. Some of the papers describe analytical methods that can be applied to one of the five steps of the damage function approach. The other papers discuss some of the complex issues that arise in trying to estimate externalities. This report, the second in a series of eight reports, is part of a joint study by the U.S. Department of Energy (DOE) and the Commission of the European Communities (EC)* on the externalities of fuel cycles. Most of the papers in this report were originally written as working papers during the initial phases of this study. The papers provide descriptions of the (non-radiological) atmospheric dispersion modeling that the study uses; reviews much of the relevant literature on ecological and health effects, and on the economic valuation of those impacts; contains several papers on some of the more complex and contentious issues in estimating externalities; and describes a method for depicting the quality of scientific information that a study uses. The analytical methods and issues that this report discusses generally pertain to more than one of the fuel cycles, though not necessarily to all of them. The report is divided into six parts, each one focusing on a different subject area.

In the 1970's, a variety of developments took place to heightened public and scientific interest in electromagnetic fields. During this time, biological studies of nonionizing electromagnetic fields were taking place, but no clear evidence of risks to public health was identified. Then came the surprising epidemiological finding suggesting that 60 Hz magnetic fields may be related to some childhood leukemias. Our particular interest at ORNL was how to interpret the available data with respect to human exposures to the nearly ubiquitous fields. A review of the available data showed that consistent biological effects were difficult to identify. Classical toxicological tests used in chemical risk assessment had not been performed with Extremely Low Frequency (ELF) fields but rather a wide range of mechanistic studies had been pursued. To evaluate the level of anticipated hazard or risk there was neither a mechanistic understanding nor a consistent phenomenological outcome. A risk evaluation normally requires one or the other of these two types of information. Two quite different approaches were pursued: meta-analysis and relative potency. The first of these is a method to combine data from similar experiments to enhance the relative statistical power of a collection of small sample size studies, and will not be discussed further. The second, relative potency, will be the focus of this paper. 20 refs., 2 figs.

It has been hypothesized that results from short-term bioassays will ultimately provide information that will be useful for human health hazard assessment. Historically, the validity of the short-term tests has been assessed using the framework of the epidemiologic/medical screens. In this context, the results of the carcinogen (long-term) bioassay is generally used as the standard. However, this approach is widely recognized as being biased and, because it employs qualitative data, cannot be used to assist in isolating those compounds which may represent a more significant toxicologic hazard than others. In contrast, the goal of this research is to address the problem of evaluating the utility of the short-term tests for hazard assessment using an alternative method of investigation. Chemicals were selected mostly from the list of carcinogens published by the International Agency for Research on Carcinogens (IARC); a few other chemicals commonly recognized as hazardous were included. Tumorigenicity and mutagenicity data on 52 chemicals were obtained from the Registry of Toxic Effects of Chemical Substances (RTECS) and were analyzed using a relative potency approach. The data were evaluated in a format which allowed for a comparison of the ranking of the mutagenic relative potencies of the compounds (as estimated using short-term data) vs. the ranking of the tumorigenic relative potencies (as estimated from the chronic bioassays). Although this was a preliminary investigation, it offers evidence that the short-term tests systems may be of utility in ranking the hazards represented by chemicals which may contribute to increased carcinogenesis in humans as a result of occupational or environmental exposures. 177 refs., 8 tabs.

Effluents from waste-water treatment facilities are discharged as a complex mixture of numerous chemical substances, which may include cytotoxic, carcinogenic, and mutagenic compounds. Historically, Federal and State Agencies have relied upon chemical-based analyses to set and enforce regulatory limits for these effluents. One problem with the approach is that many potentially hazardous chemicals may not be quantifiable in complex chemical effluents but are none the less discharged into the environment. The U.S. Environmental Protection Agency has recently established a research program to determine if a bioassay approach for evaluating the potential adverse human health effects from exposure to complex mixtures might supplement conventional chemical analysis for setting regulatory limits for waste-waters. This report summarizes a bioassay testing strategy for characterizing cytotoxic and mutagenic activity of various waste-water effluents. The use of a relative potency framework for assessing complex mixtures for potential health hazards is addressed.

The Department of Defense's Installation Restoration Program requires the identification and evaluation of sites where hazardous materials were disposed of in the past. Oak Ridge National Laboratory has developed a site-rating system, referred to as the Defense Priority Model (DPM), which is intended for use in determining priorities for remedial action at contaminated sites. In the DPM, the human health hazards and ecological hazards of contaminants identified through monitoring are assessed, using toxicological benchmarks and bioaccumulation factors that relate the concentrations measured to concentrations or doses that may be toxic to man or to nonhuman biota. A user's manual for the DPM has already been published. This report supports the user's manual by documenting (1) the methods and data sources used to develop the benchmarks and bioaccumulation factors and (2) the procedure for using these values to calculate health and ecological hazard scores. 95 refs., 4 figs., 13 tabs.

Current methods for the toxicologic evaluation of complex mixture approaches the problem from the interaction of the individual chemicals constituting the mixture; complex mixtures produce health effects that can be additive, antagonistic, or synergistic relative to the components acting along. Most exposures are limited to mixtures. One option is to conceptually approach the complex mixture as a unique chemical. The evaluation of that mixture would proceed in a similar fashion to that of any empirical toxicologic analysis. Because the use of whole animal test systems for the analysis of every mixture would not be cost effective, this project develops a framework for the use of in vitro assays to assist in this type of evaluation. 12 refs., 3 tabs.