Toxicity Testing For Assessment Of Environmental Agents

Toxicity testing in laboratory animals provides much of the information used by the Environmental Protection Agency (EPA) to assess the hazards and risks associated with exposure to environmental agents that might harm public health or the environment. The data are used to establish maximum acceptable concentrations of environmental agents in drinking water, set permissible limits of exposure of workers, define labeling requirements, establish tolerances for pesticides residues on food, and set other kinds of limits on the basis of risk assessment. Because the number of regulations that require toxicity testing is growing, EPA called for a comprehensive review of established and emerging toxicity-testing methods and strategies. This interim report reviews current toxicity-testing methods and strategies and near-term improvements in toxicity-testing approaches proposed by EPA and others. It identifies several recurring themes and questions in the various reports reviewed. The final report will present a long-range vision and strategic plan to advance the practices of toxicity testing and human health assessment of environmental contaminants.

Advances in molecular biology and toxicology are paving the way for major improvements in the evaluation of the hazards posed by the large number of chemicals found at low levels in the environment. The National Research Council was asked by the U.S. Environmental Protection Agency to review the state of the science and create a far-reaching vision for the future of toxicity testing. The book finds that developing, improving, and validating new laboratory tools based on recent scientific advances could significantly improve our ability to understand the hazards and risks posed by chemicals. This new knowledge would lead to much more informed environmental regulations and dramatically reduce the need for animal testing because the new tests would be based on human cells and cell components. Substantial scientific efforts and resources will be required to leverage these new technologies to realize the vision, but the result will be a more efficient, informative and less costly system for assessing the hazards posed by industrial chemicals and pesticides.

As an integral component of environmental policy, it has become essential to regulate and monitor toxic substances. Past emphasis has been primarily on analytical approaches to the detection of specific, targeted contaminants, thus allowing chemical characterisation. However, toxicity testing or biological assessment is necessary for ecotoxicological evaluation, and this offers marked benefits and advantages that complement chemical analysis. Key issues to be addressed include identification of pertinent tests, reproducibility and robustness of these tests, and cost considerations.This book examines these issues and describes and explains the approaches that have been developed for environmental toxicity evaluations. Advantages, benefits and drawbacks of the strategies and methods are highlighted. Directed equally at ecotoxicologists, industrial chemists, analytical chemists and environmental consultants, this book is written in a way that will prove helpful to both new and experienced practitioners.

Risk assessment has become a dominant public policy tool for making choices, based on limited resources, to protect public health and the environment. It has been instrumental to the mission of the U.S. Environmental Protection Agency (EPA) as well as other federal agencies in evaluating public health concerns, informing regulatory and technological decisions, prioritizing research needs and funding, and in developing approaches for cost-benefit analysis. However, risk assessment is at a crossroads. Despite advances in the field, risk assessment faces a number of significant challenges including lengthy delays in making complex decisions; lack of data leading to significant uncertainty in risk assessments; and many chemicals in the marketplace that have not been evaluated and emerging agents requiring assessment. Science and Decisions makes practical scientific and technical recommendations to address these challenges. This book is a complement to the widely used 1983 National Academies book, Risk Assessment in the Federal Government (also known as the Red Book). The earlier book established a framework for the concepts and conduct of risk assessment that has been adopted by numerous expert committees, regulatory agencies, and public health institutions. The new book embeds these concepts within a broader framework for risk-based decision-making. Together, these are essential references for those working in the regulatory and public health fields.

Historically, regulations governing chemical use have often focused on widely used chemicals and acute human health effects of exposure to them, as well as their potential to cause cancer and other adverse health effects. As scientific knowledge has expanded there has been an increased awareness of the mechanisms through which chemicals may exert harmful effects on human health, as well as their effects on other species and ecosystems. Identification of high-priority chemicals and other chemicals of concern has prompted a growing number of state and local governments, as well as major companies, to take steps beyond existing hazardous chemical federal legislation. Interest in approaches and policies that ensure that any new substances substituted for chemicals of concern are assessed as carefully and thoroughly as possible has also burgeoned. The overarching goal of these approaches is to avoid regrettable substitutions, which occur when a toxic chemical is replaced by another chemical that later proved unsuitable because of persistence, bioaccumulation, toxicity, or other concerns. Chemical alternative assessments are tools designed to facilitate consideration of these factors to assist stakeholders in identifying chemicals that may have the greatest likelihood of harm to human and ecological health, and to provide guidance on how the industry may develop and adopt safer alternatives. A Framework to Guide Selection of Chemical Alternatives develops and demonstrates a decision framework for evaluating potentially safer substitute chemicals as primarily determined by human health and ecological risks. This new framework is informed by previous efforts by regulatory agencies, academic institutions, and others to develop alternative assessment frameworks that could be operationalized. In addition to hazard assessments, the framework incorporates steps for life-cycle thinking - which considers possible impacts of a chemical at all stages including production, use, and disposal - as well as steps for performance and economic assessments. The report also highlights how modern information sources such as computational modeling can supplement traditional toxicology data in the assessment process. This new framework allows the evaluation of the full range of benefits and shortcomings of substitutes, and examination of tradeoffs between these risks and factors such as product functionality, product efficacy, process safety, and resource use. Through case studies, this report demonstrates how different users in contrasting decision contexts with diverse priorities can apply the framework. This report will be an essential resource to the chemical industry, environmentalists, ecologists, and state and local governments.