Toxicity Testing in the 21st Century A Vision and a Strategy (2007) / Chapter Skim
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1 Introduction
1 Introduction
Pages 18-34
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From page 18... ...
That approach has led to a system that is somewhat cumbersome with respect to the cost of testing, the use of laboratory animals, and the time needed to generate and review data. In combination with varied statutory requirements for testing, it has also resulted in a system in which there are substantial differences in chemical testing, many chemicals not being tested at all despite potential human exposure to them.
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19 Introduction vened the Committee on Toxicity Testing and Assessment of Environmental Agents, which prepared this report. HISTORICAL PERSPECTIVE OF REGULATORY TOXICOLOGY To gain an appreciation of current toxicity-testing strategies, it is helpful to examine how they evolved, why differences arose among and within federal agencies, and who contributed to the process.
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20 Toxicity Testing in the 21st Century before it could be marketed. The approval process thus changed from one based on premarket notification to one based on premarket approval.
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The other critical pieces of legislation that helped to shape the current toxicity-testing strategy for pesticides were amendments to the FDCA. In 1954, the Miller Amendment "required that a maximum acceptable level (tolerance)
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FDA's drug and food-additive testing programs and EPA's pesticide testing program represent strategies designed to support safety evaluations of chemicals before specified uses. Other testing can occur in response to regulatory concerns regarding environmental agents.
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23 Introduction of medium- and high-throughput tests to address the evergrowing number of newly introduced chemicals and the existing chemicals and breakdown products that have not been tested.2 Tests proposed by NTP and others that are alternatives to standard protocols are formally reviewed by an interagency authority, the Interagency Coordinating Committee on the Validation of Alternative Methods, to ensure that they have value in regulatory decision-making. Another organization that has influenced toxicity-testing programs in the United States is the Organisation for Economic Co-operation and Development (OECD)
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The research phase is marked by data generation and method development, including basic research and routine testing. For any particular risk assessment, the data used may have many sources, including studies of laboratory animals, clinical tests, epidemiologic studies, and studies of animal and human cells in culture.
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The present report identifies some of those considerations and other, public-health considerations as "risk contexts" and underlines their important role in decisions related to toxicity testing (see discussion under "The Committee's Second Task and Approach" in this chapter)
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Agencies typically have responded to scientific advances and emerging challenges by simply altering individual tests or adding tests to existing regimens. That patchwork approach has not provided a fully satisfactory solution to the fundamental problem -- the difficulty in meeting four objectives simultaneously: depth, providing the most accurate, relevant information possible for hazard identification and dose-response assessment; breadth, providing data on the broadest possible universe of chemicals, end points, and life stages; animal welfare, causing the least animal suffering possible and using the fewest ani
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How can environmental agents be screened with minimal use of animals and efficient expenditure of time and other resources? How should tests and testing strategies be evaluated?
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Testing every chemical for every possible health effect over all life stages is impractical; however, the emerging technologies hold great promise for screening chemicals more rapidly. Fourth, testing strategies will need to be evaluated with respect to the value of information that they provide in light of the four objectives discussed above -- depth, breadth, animal welfare, and conservation.
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To prepare its final report, the committee held six meetings from April 2005 to June 2006. Three of the meetings included public sessions during which the committee heard presentations by staff of several EPA offices, including the Office of Prevention, Pesticides and Toxic Substances, the Office of Children's Health Protection, the Office of Water, the Office of Solid Waste and Emergency Response, and the Office of Air and Radiation.
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In some cases, a need to evaluate specific existing environmental agents may arise from the discovery of a new source or exposure pathway or from a better understanding of human exposure on the basis of, for example, biomonitoring data. In other cases, scrutiny may be necessary when toxicity is newly recognized, such as toxicity in a worker population.
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That understanding has allowed decision-makers to take action against some pollutants, but other causes or triggers of asthma could yet be discovered. • Evaluation of the relative risks posed by environmental agents.
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In Chapter 2, the committee discusses the limitations of the current toxicity-testing system, the design goals for a new system, and the options considered by the committee. An overview of the new long-range vision for toxicity testing of environmental agents is also presented.
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2004a. Systemic Toxicity White Paper.
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Life Stages Task Force, Technical Committee on Agricultural Chemical Safety Assessment, ILSI Health Sciences Institute, Washington, DC. November 2, 2004.
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