Risk assessment is a relatively new and rapidly developing science. Indeed, most federal agencies for which risk assessment is an important tool for decision-making or a subject of research were established only within the last quarter-century. Among those are the Environmental Protection Agency (EPA), Occupational Safety and Health Administration (OSHA), Consumer Product Safety Commission (CPSC), National Institute of Environmental Health Sciences (NIEHS), National Institute for Occupational Safety and Health (NIOSH), Food and Drug Administration (FDA), and Agency for Toxic Substances and Disease Registry (ATSDR). Mantel and Bryan published in 1961 the first paper on estimation of low dose risk based on data obtained from tests in which animals were exposed at high doses; formal procedures for performing animal bioassays, which are critically important for gathering information for risk assessment, had been standardized only in the 1960s and 1970s; and formal risk assessment began to be conducted regularly in the late 1970s. It was not until 1983, when the National Research Council (NRC) committee that prepared Risk Assessment in the Federal Government: Managing the Process defined the steps in risk assessment, that a generally accepted nomenclature for risk assessment was established.
Now, after this short time, risk assessment scientists study the details and argue the relative merits of different approaches to the performance and interpretation of studies; learned societies publish journals to communicate these deliberations; and national and international meetings are
convened to discuss specific issues or to write the blueprints for new programs. New concepts are being rapidly explored, such as the use of pharmacokinetic studies of the fate of a chemical agent in the body; and some of the practices and principles established only a few years ago are already being re-evaluated. In addition, whereas almost all efforts were once directed toward determining the carcinogenic potential of an agent, scientists are now equally interested in assessing the potential of mixtures of agents to produce not only cancer, but reproductive, neurotoxic, developmental, and immunologic effects.
This volume contains the first three reports the Committee on Risk Assessment Methodology (CRAM) in the National Research Council (NRC) Board on Environmental Studies and Toxicology. The committee's work was sponsored by a consortium of federal agencies and private organizations, including EPA, NIOSH, the U.S. Army Biomedical Research and Development Laboratory, the American Petroleum Institute, and the American Industrial Health Council. The committee was charged to assess the scientific basis, inference assumptions, and regulatory uses of and research need in risk assessment. The committee has investigated these issues partly through a series of narrowly focused workshops. Topics were chosen in consultation with federal regulatory agencies on the basis of scientific considerations and the needs of the agencies. One source is a list of subjects that appeared in Risk Assessment if the Federal Government, which has become known as the Red Book. CRAM's reports are intended to provide guidance to regulatory decision-makers on specific questions; they are not broad, thorough scientific analyses, as are many NRC reports. The committee has focused on methodology; accordingly, its deliberations on each topic takes into account not only potential problems with existing methods, but also the suitability of alternative methods for risk assessment.
The committee consulted closely with federal agencies whose mission is to make decisions based on risk assessment of environmental and human health hazards. Representatives of 11 federal agencies organized themselves as a federal liaison group, and the committee consulted with the group in selecting workshop topics and participants and in preparing workshop summaries. However, in accordance with NRC policy, the members of the federal liaison group did not take part in the committee's deliberations or in the preparation of its reports. The workshop presentations, commissioned papers, and extensive committee deliberations formed the basis for the findings in the reports.