Toxicity Testing in the 21st Century A Vision and a Strategy (2007) / Chapter Skim
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6 Prerequisites for Implementing the Vision in Regulatory Contexts
6 Prerequisites for Implementing the Vision in Regulatory Contexts
Pages 166-183
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From page 166... ...
6 Prerequisites for Implementing the Vision in Regulatory Contexts The committee's vision sets the stage for transformative changes in toxicity testing in the regulatory agencies and the larger scientific community. Although advances in the state of the science are indispensable to realization of the vision, corresponding institutional changes are also important.
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Beyond the scientific and procedural considerations summarized in this chapter, the state of the economy, changing environmental conditions and social perspectives, and other dynamics that shape the political climate will influence legislative changes and federal budgets that, in turn, will determine the future of toxicity testing in the regulatory context. INSTITUTIONAL CHANGE TO MEET THE VISION Attitudes and Expectations Full realization of the vision depends on the promotion of new testing principles and methods in the scientific community at large.
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For several decades, academic institutions have prepared scientists for toxicity testing and risk analysis through training in
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Policies to Foster Development and Use of New Tests Institutional change does not come easily. The history of toxicity testing indicates that the pace and extent of change will depend in part on policies and incentives.
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170 Toxicity Testing in the 21st Century tives to encourage the use and development of the new tests by agencies are discussed here. First, continued progress in the use of the new technologies constitutes the greatest incentive to reconfiguring agency testing programs in line with the vision.
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Environmental Protection Agency (EPA) , the availability of reliable data on "adverse effects" and health or environmental "risk" is an underlying assumption in them.
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172 Toxicity Testing in the 21st Century specific categories of data to the agency. Other statutes -- such as the Clean Air Act, the Clean Water Act, and the Safe Drinking Water Act -- require toxicity data to be considered but depend mainly on information available in the scientific literature or government laboratory reports.1 Regardless of the statute or the data source, toxicity data are indispensable for well-reasoned conclusions on the nature and dimensions of risk and for wellgrounded decisions on the necessity of regulation to protect the public health or the environment and on the nature and scope of any such regulations.
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Prerequisites for Implementing the Vision in Regulatory Contexts 173 aspects to validation, so the discussion also addresses administrative policies and procedures and other nonscientific considerations related to promulgating and defending government testing practices and requirements.3 Scientific Prerequisites of Validity The federal agencies have a 75-year history of developing and promulgating toxicity-testing requirements for external entities, such as pesticide and drug manufacturers, and internal guidance for government laboratories (see Chapter 1)
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Regulatory agencies also use in vitro systems for toxicity testing and risk assessment. In vitro mode-of-action data were central elements when EPA proposed revisions to the cancer guidelines more than 10 years ago and in the final guidelines (EPA 2005)
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modeling human metabo lism…; (b) maintaining tissue-specific function in vitro; (c)
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For example, the Safe Drinking Water Act calls for establishing contaminant concentrations at which "no known or anticipated adverse effects on the health of persons occur and which allows an adequate margin of safety." A FIFRA provision calls for preventing "unrea
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However, despite the historical emphasis, scientific and regulatory sources make clear that adverse effects embrace a wide array of end-point categories. Table 6-1 provides some definitions that are consistent with the vision's approach to toxicity testing.
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178 Toxicity Testing in the 21st Century TABLE 6-1 Definitions of Adverse Effect Definition Source IRIS 2007 "Adverse effect: A biochemical change, functional impairment, or pathologic lesion that affects the performance of the whole organism, or reduces an organism's ability to respond to an additional environmental challenge." Renwick et al. "Adverse effect: Change in the morphology, 2003 physiology, growth, development or life span of an organism, system or (sub)
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The scientific principles and methods involved in the implementation of the committee's vision are well known in the scientific community, a major constituency in the discussion of the scientific validity of data derived from toxicity tests for regulatory use. Scientists have long recognized the importance of effective communication of scientific results to a wide variety of stakeholders in toxicity testing, including other scientists, regulatory authorities, industry, the mass media, nongovernment organizations, and the public (NRC 1989; Leiss 2001; Krewski et al.
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Acceptance of the committee's vision in the scientific community will require further elaboration of the technical details of its implementation and generation of new scientific evidence to support the move away from apical end points to perturbations of toxicity pathways. The broad participation of the scientific community in the elaboration of the committee's vision for toxicity testing is essential for its success.
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. CalEPA (California Environmental Protection Agency)
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EPA (U.S. Environmental Protection Agency)
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Inte grated Risk Information System, U.S. Environmental Protection Agency [online]
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