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Fenner-Crisp PA, Dellarco VL. Key Elements for Judging the Quality of a Risk Assessment. ENVIRONMENTAL HEALTH PERSPECTIVES 2016; 124:1127-35. [PMID: 26862984 PMCID: PMC4977059 DOI: 10.1289/ehp.1510483] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 09/30/2015] [Accepted: 01/21/2016] [Indexed: 05/03/2023]
Abstract
BACKGROUND Many reports have been published that contain recommendations for improving the quality, transparency, and usefulness of decision making for risk assessments prepared by agencies of the U.S. federal government. A substantial measure of consensus has emerged regarding the characteristics that high-quality assessments should possess. OBJECTIVE The goal was to summarize the key characteristics of a high-quality assessment as identified in the consensus-building process and to integrate them into a guide for use by decision makers, risk assessors, peer reviewers and other interested stakeholders to determine if an assessment meets the criteria for high quality. DISCUSSION Most of the features cited in the guide are applicable to any type of assessment, whether it encompasses one, two, or all four phases of the risk-assessment paradigm; whether it is qualitative or quantitative; and whether it is screening level or highly sophisticated and complex. Other features are tailored to specific elements of an assessment. Just as agencies at all levels of government are responsible for determining the effectiveness of their programs, so too should they determine the effectiveness of their assessments used in support of their regulatory decisions. Furthermore, if a nongovernmental entity wishes to have its assessments considered in the governmental regulatory decision-making process, then these assessments should be judged in the same rigorous manner and be held to similar standards. CONCLUSIONS The key characteristics of a high-quality assessment can be summarized and integrated into a guide for judging whether an assessment possesses the desired features of high quality, transparency, and usefulness. CITATION Fenner-Crisp PA, Dellarco VL. 2016. Key elements for judging the quality of a risk assessment. Environ Health Perspect 124:1127-1135; http://dx.doi.org/10.1289/ehp.1510483.
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Egeghy PP, Sheldon LS, Isaacs KK, Özkaynak H, Goldsmith MR, Wambaugh JF, Judson RS, Buckley TJ. Computational Exposure Science: An Emerging Discipline to Support 21st-Century Risk Assessment. ENVIRONMENTAL HEALTH PERSPECTIVES 2016; 124:697-702. [PMID: 26545029 PMCID: PMC4892918 DOI: 10.1289/ehp.1509748] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 10/30/2015] [Indexed: 05/19/2023]
Abstract
BACKGROUND Computational exposure science represents a frontier of environmental science that is emerging and quickly evolving. OBJECTIVES In this commentary, we define this burgeoning discipline, describe a framework for implementation, and review some key ongoing research elements that are advancing the science with respect to exposure to chemicals in consumer products. DISCUSSION The fundamental elements of computational exposure science include the development of reliable, computationally efficient predictive exposure models; the identification, acquisition, and application of data to support and evaluate these models; and generation of improved methods for extrapolating across chemicals. We describe our efforts in each of these areas and provide examples that demonstrate both progress and potential. CONCLUSIONS Computational exposure science, linked with comparable efforts in toxicology, is ushering in a new era of risk assessment that greatly expands our ability to evaluate chemical safety and sustainability and to protect public health. CITATION Egeghy PP, Sheldon LS, Isaacs KK, Özkaynak H, Goldsmith M-R, Wambaugh JF, Judson RS, Buckley TJ. 2016. Computational exposure science: an emerging discipline to support 21st-century risk assessment. Environ Health Perspect 124:697-702; http://dx.doi.org/10.1289/ehp.1509748.
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Affiliation(s)
- Peter P. Egeghy
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | | | - Kristin K. Isaacs
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | | | - Michael-Rock Goldsmith
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - John F. Wambaugh
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Richard S. Judson
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Timothy J. Buckley
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
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Bal-Price A, Lein PJ, Keil KP, Sethi S, Shafer T, Barenys M, Fritsche E, Sachana M, Meek MEB. Developing and applying the adverse outcome pathway concept for understanding and predicting neurotoxicity. Neurotoxicology 2016; 59:240-255. [PMID: 27212452 DOI: 10.1016/j.neuro.2016.05.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 05/13/2016] [Accepted: 05/13/2016] [Indexed: 12/12/2022]
Abstract
The Adverse Outcome Pathway (AOP) concept has recently been proposed to support a paradigm shift in regulatory toxicology testing and risk assessment. This concept is similar to the Mode of Action (MOA), in that it describes a sequence of measurable key events triggered by a molecular initiating event in which a stressor interacts with a biological target. The resulting cascade of key events includes molecular, cellular, structural and functional changes in biological systems, resulting in a measurable adverse outcome. Thereby, an AOP ideally provides information relevant to chemical structure-activity relationships as a basis for predicting effects of structurally similar compounds. AOPs could potentially also form the basis for qualitative and quantitative predictive modeling of the human adverse outcome resulting from molecular initiating or other key events for which higher-throughput testing methods are available or can be developed. A variety of cellular and molecular processes are known to be critical for normal function of the central (CNS) and peripheral nervous systems (PNS). Because of the biological and functional complexity of the CNS and PNS, it has been challenging to establish causative links and quantitative relationships between key events that comprise the pathways leading from chemical exposure to an adverse outcome in the nervous system. Following introduction of the principles of MOA and AOPs, examples of potential or putative adverse outcome pathways specific for developmental or adult neurotoxicity are summarized and aspects of their assessment considered. Their possible application in developing mechanistically informed Integrated Approaches to Testing and Assessment (IATA) is also discussed.
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Affiliation(s)
- Anna Bal-Price
- European Commission Joint Research Centre, Institute for Health and Consumer Protection, Ispra, Italy.
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA
| | - Kimberly P Keil
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA
| | - Sunjay Sethi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA
| | - Timothy Shafer
- Integrated Systems Toxicology Division, Office of Research and Development, U.S. Environmental Protection Agency, RTP, USA
| | - Marta Barenys
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Ellen Fritsche
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Magdalini Sachana
- European Commission Joint Research Centre, Institute for Health and Consumer Protection, Ispra, Italy
| | - M E Bette Meek
- McLaughlin Centre for Risk Science, University of Ottawa, Ottawa, Canada
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Meek M(B, Lipscomb JC. Gaining acceptance for the use of in vitro toxicity assays and QIVIVE in regulatory risk assessment. Toxicology 2015; 332:112-23. [DOI: 10.1016/j.tox.2015.01.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 12/31/2014] [Accepted: 01/14/2015] [Indexed: 12/01/2022]
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Becker RA, Ankley GT, Edwards SW, Kennedy SW, Linkov I, Meek B, Sachana M, Segner H, Van Der Burg B, Villeneuve DL, Watanabe H, Barton-Maclaren TS. Increasing Scientific Confidence in Adverse Outcome Pathways: Application of Tailored Bradford-Hill Considerations for Evaluating Weight of Evidence. Regul Toxicol Pharmacol 2015; 72:514-37. [PMID: 25863193 DOI: 10.1016/j.yrtph.2015.04.004] [Citation(s) in RCA: 173] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 04/04/2015] [Accepted: 04/06/2015] [Indexed: 10/23/2022]
Abstract
Systematic consideration of scientific support is a critical element in developing and, ultimately, using adverse outcome pathways (AOPs) for various regulatory applications. Though weight of evidence (WoE) analysis has been proposed as a basis for assessment of the maturity and level of confidence in an AOP, methodologies and tools are still being formalized. The Organization for Economic Co-operation and Development (OECD) Users' Handbook Supplement to the Guidance Document for Developing and Assessing AOPs (OECD 2014a; hereafter referred to as the OECD AOP Handbook) provides tailored Bradford-Hill (BH) considerations for systematic assessment of confidence in a given AOP. These considerations include (1) biological plausibility and (2) empirical support (dose-response, temporality, and incidence) for Key Event Relationships (KERs), and (3) essentiality of key events (KEs). Here, we test the application of these tailored BH considerations and the guidance outlined in the OECD AOP Handbook using a number of case examples to increase experience in more transparently documenting rationales for assigned levels of confidence to KEs and KERs, and to promote consistency in evaluation within and across AOPs. The major lessons learned from experience are documented, and taken together with the case examples, should contribute to better common understanding of the nature and form of documentation required to increase confidence in the application of AOPs for specific uses. Based on the tailored BH considerations and defining questions, a prototype quantitative model for assessing the WoE of an AOP using tools of multi-criteria decision analysis (MCDA) is described. The applicability of the approach is also demonstrated using the case example aromatase inhibition leading to reproductive dysfunction in fish. Following the acquisition of additional experience in the development and assessment of AOPs, further refinement of parameterization of the model through expert elicitation is recommended. Overall, the application of quantitative WoE approaches hold promise to enhance the rigor, transparency and reproducibility for AOP WoE determinations and may play an important role in delineating areas where research would have the greatest impact on improving the overall confidence in the AOP.
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Affiliation(s)
| | - Gerald T Ankley
- US Environmental Protection Agency, Office of Research and Development, Mid-Continent Ecology Division, Duluth, MN, USA
| | - Stephen W Edwards
- US Environmental Protection Agency, Office of Research and Development, Integrated Systems Toxicology Division, Research Triangle Park, NC, USA
| | - Sean W Kennedy
- Environment Canada, National Wildlife Research Centre, Ottawa, Ontario, Canada
| | - Igor Linkov
- Environmental Laboratory, Engineer Research and Development Center, US Army Corps of Engineers, Concord, MA, USA
| | - Bette Meek
- University of Ottawa, Ottawa, Ontario, Canada
| | - Magdalini Sachana
- European Commission, Joint Research Centre, Via E. Fermi 2749, 21027, Ispra, Italy
| | - Helmut Segner
- Centre for Fish and Wildlife Health, University of Bern, Bern, Switzerland
| | | | - Daniel L Villeneuve
- US Environmental Protection Agency, Office of Research and Development, Mid-Continent Ecology Division, Duluth, MN, USA
| | - Haruna Watanabe
- Center for Environmental Risk Research, National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
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Mayo M, Collier ZA, Hoang V, Chappell M. Uncertainty in multi-media fate and transport models: a case study for TNT life cycle assessment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 494-495:104-112. [PMID: 25037048 DOI: 10.1016/j.scitotenv.2014.06.061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 06/05/2014] [Accepted: 06/15/2014] [Indexed: 06/03/2023]
Abstract
Life cycle assessment (LCA) is an evaluation method used by decision-makers to help assess the relative environmental impacts of various industrial processes. Despite that many LCA methods remain sensitive to uncertain input data, which can reduce the utility of their results, uncertainty arising from constituent LCA models remains poorly understood. Here, we begin to address this problem by evaluating the extent to which parameter-value uncertainty affects the SimpleBox 2.0 fate and transport model, which serves as a backbone for many LCA ecotoxicological impact categories. Two Monte Carlo type sampling methods were used to evaluate dispersion in steady-state concentration values for three chemicals involved in grenade production: toluene, 2,4-dinitrotoluene (2,4-DNT), and 2,4,6-trinitrotoluene (TNT). Parameters were first sampled stochastically one-at-a-time, then by randomly exploring a local patch of the parameter space. We confirmed that global temperatures contribute primarily to the overall variance of model results, which at most spanned approximately 8 decades in magnitude. These results are consistent with previous results obtained for the whole of the LCA method. LCA methods carry out calculations iteratively; a reduction in the error of a single component, such as the fate and transport model, may therefore improve its performance and utility as a decision-making aid.
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Affiliation(s)
- Michael Mayo
- Environmental Laboratory, US Army Engineer Research and Development Center, Vicksburg, MS, USA
| | - Zachary A Collier
- Environmental Laboratory, US Army Engineer Research and Development Center, Vicksburg, MS, USA
| | - Vu Hoang
- Department of Biosystems Engineering, Michigan State University, East Lansing, MI, USA
| | - Mark Chappell
- Environmental Laboratory, US Army Engineer Research and Development Center, Vicksburg, MS, USA.
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Gehen SC, Blacker AM, Boverhof DR, Hanley TR, Hastings CE, Ladics GS, Lu H, O’Neal FO. Retrospective evaluation of the impact of functional immunotoxicity testing on pesticide hazard identification and risk assessment. Crit Rev Toxicol 2014; 44:407-19. [DOI: 10.3109/10408444.2014.882291] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Meek ME, Boobis A, Cote I, Dellarco V, Fotakis G, Munn S, Seed J, Vickers C. New developments in the evolution and application of the WHO/IPCS framework on mode of action/species concordance analysis. J Appl Toxicol 2013; 34:1-18. [PMID: 24166207 PMCID: PMC6701984 DOI: 10.1002/jat.2949] [Citation(s) in RCA: 184] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 09/19/2013] [Indexed: 01/25/2023]
Abstract
The World Health Organization/International Programme on Chemical Safety mode of action/human relevance framework has been updated to reflect the experience acquired in its application and extend its utility to emerging areas in toxicity testing and non-testing methods. The underlying principles have not changed, but the framework’s scope has been extended to enable integration of information at different levels of biological organization and reflect evolving experience in a much broader range of potential applications. Mode of action/species concordance analysis can also inform hypothesis-based data generation and research priorities in support of risk assessment. The modified framework is incorporated within a roadmap, with feedback loops encouraging continuous refinement of fit-for-purpose testing strategies and risk assessment. Important in this construct is consideration of dose–response relationships and species concordance analysis in weight of evidence. The modified Bradford Hill considerations have been updated and additionally articulated to reflect increasing experience in application for cases where the toxicological outcome of chemical exposure is known. The modified framework can be used as originally intended, where the toxicological effects of chemical exposure are known, or in hypothesizing effects resulting from chemical exposure, using information on putative key events in established modes of action from appropriate in vitro or in silico systems and other lines of evidence. This modified mode of action framework and accompanying roadmap and case examples are expected to contribute to improving transparency in explicitly addressing weight of evidence considerations in mode of action/species concordance analysis based on both conventional data sources and evolving methods.
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Affiliation(s)
- M E Meek
- Chemical Risk Assessment, McLaughlin Centre for Population Health Risk Assessment, 1 Stewart Street, Ottawa, Ontario, Canada, K1N 6N5
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Bhat VS, Hester SD, Nesnow S, Eastmond DA. Concordance of Transcriptional and Apical Benchmark Dose Levels for Conazole-Induced Liver Effects in Mice. Toxicol Sci 2013; 136:205-15. [DOI: 10.1093/toxsci/kft182] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Mitchell J, Pabon N, Collier ZA, Egeghy PP, Cohen-Hubal E, Linkov I, Vallero DA. A decision analytic approach to exposure-based chemical prioritization. PLoS One 2013; 8:e70911. [PMID: 23940664 PMCID: PMC3733911 DOI: 10.1371/journal.pone.0070911] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 06/25/2013] [Indexed: 11/18/2022] Open
Abstract
The manufacture of novel synthetic chemicals has increased in volume and variety, but often the environmental and health risks are not fully understood in terms of toxicity and, in particular, exposure. While efforts to assess risks have generally been effective when sufficient data are available, the hazard and exposure data necessary to assess risks adequately are unavailable for the vast majority of chemicals in commerce. The US Environmental Protection Agency has initiated the ExpoCast Program to develop tools for rapid chemical evaluation based on potential for exposure. In this context, a model is presented in which chemicals are evaluated based on inherent chemical properties and behaviorally-based usage characteristics over the chemical's life cycle. These criteria are assessed and integrated within a decision analytic framework, facilitating rapid assessment and prioritization for future targeted testing and systems modeling. A case study outlines the prioritization process using 51 chemicals. The results show a preliminary relative ranking of chemicals based on exposure potential. The strength of this approach is the ability to integrate relevant statistical and mechanistic data with expert judgment, allowing for an initial tier assessment that can further inform targeted testing and risk management strategies.
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Affiliation(s)
- Jade Mitchell
- Biosystems & Agricultural Engineering, Michigan State University, East Lansing, Michigan, United States of America
| | - Nicolas Pabon
- Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Zachary A. Collier
- Environmental Laboratory, Engineer Research and Development Center, United States Army Corps of Engineers, Concord, Massachusetts, United States of America
| | - Peter P. Egeghy
- Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, North Carolina, United States of America
| | - Elaine Cohen-Hubal
- Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, North Carolina, United States of America
| | - Igor Linkov
- Environmental Laboratory, Engineer Research and Development Center, United States Army Corps of Engineers, Concord, Massachusetts, United States of America
- * E-mail:
| | - Daniel A. Vallero
- Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, North Carolina, United States of America
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11
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LeBaron MJ, Geter DR, Rasoulpour RJ, Gollapudi BB, Thomas J, Murray J, Kan HL, Wood AJ, Elcombe C, Vardy A, McEwan J, Terry C, Billington R. An integrated approach for prospectively investigating a mode-of-action for rodent liver effects. Toxicol Appl Pharmacol 2013; 270:164-73. [DOI: 10.1016/j.taap.2013.04.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/28/2013] [Accepted: 04/01/2013] [Indexed: 12/26/2022]
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Dellarco V, Fenner-Crisp PA. Mode of action: moving toward a more relevant and efficient assessment paradigm. J Nutr 2012; 142:2192S-2198S. [PMID: 23096006 DOI: 10.3945/jn.111.157396] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
To advance the utility and predictability of safety evaluation, an integrated approach that relies on all existing knowledge to understand how agents perturb normal biological function or structure is needed to progress more focused evaluation strategies. The mode of action (MOA)-human relevance framework developed by the International Program for Chemical Safety and The International Life Sciences Institute provides a useful analytical approach where different lines of evidence (e.g., in vitro, in vivo) can be organized, linked, and integrated at different levels of biological organization into a more efficient, hypothesis-driven approach to safety evaluation. This framework provides a weight-of-evidence approach based on considerations for causality (as originally articulated by Bradford Hill), including dose response and temporal concordance, consistency, specificity, and biological plausibility and coherence. Once an animal MOA and its key events are established, qualitative and quantitative comparisons between experimental animals and humans are made based on the key events. This comparison enables a conclusion as to whether the MOA is likely operative in humans and, if so, whether it can result in a more refined hazard and dose-response assessment. This framework provides an important tool to promote and formalize the use of MOA data in safety evaluation regardless of whether the information comes from traditional or novel approaches, such as those recommended by the NRC in its 2007 report "Toxicity Testing in the 21st Century," which recommends moving away from traditional approaches of measuring adverse endpoints by using newer technologies to identify ways agents may considerably perturb cellular pathways to produce their toxicity.
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Affiliation(s)
- Vicki Dellarco
- U.S. Environmental Protection Agency, Office of Pesticide Programs, Washington, DC, USA.
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Stephens ML, Barrow C, Andersen ME, Boekelheide K, Carmichael PL, Holsapple MP, Lafranconi M. Accelerating the development of 21st-century toxicology: outcome of a Human Toxicology Project Consortium workshop. Toxicol Sci 2011; 125:327-34. [PMID: 21948868 PMCID: PMC3262850 DOI: 10.1093/toxsci/kfr248] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The U.S. National Research Council (NRC) report on "Toxicity Testing in the 21st century" calls for a fundamental shift in the way that chemicals are tested for human health effects and evaluated in risk assessments. The new approach would move toward in vitro methods, typically using human cells in a high-throughput context. The in vitro methods would be designed to detect significant perturbations to "toxicity pathways," i.e., key biological pathways that, when sufficiently perturbed, lead to adverse health outcomes. To explore progress on the report's implementation, the Human Toxicology Project Consortium hosted a workshop on 9-10 November 2010 in Washington, DC. The Consortium is a coalition of several corporations, a research institute, and a non-governmental organization dedicated to accelerating the implementation of 21st-century Toxicology as aligned with the NRC vision. The goal of the workshop was to identify practical and scientific ways to accelerate implementation of the NRC vision. The workshop format consisted of plenary presentations, breakout group discussions, and concluding commentaries. The program faculty was drawn from industry, academia, government, and public interest organizations. Most presentations summarized ongoing efforts to modernize toxicology testing and approaches, each with some overlap with the NRC vision. In light of these efforts, the workshop identified recommendations for accelerating implementation of the NRC vision, including greater strategic coordination and planning across projects (facilitated by a steering group), the development of projects that test the proof of concept for implementation of the NRC vision, and greater outreach and communication across stakeholder communities.
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Affiliation(s)
- Martin L Stephens
- The Humane Society of United States, Washington, District of Columbia 20037, USA.
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Bhattacharya S, Zhang Q, Carmichael PL, Boekelheide K, Andersen ME. Toxicity testing in the 21 century: defining new risk assessment approaches based on perturbation of intracellular toxicity pathways. PLoS One 2011; 6:e20887. [PMID: 21701582 PMCID: PMC3118802 DOI: 10.1371/journal.pone.0020887] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 05/11/2011] [Indexed: 01/15/2023] Open
Abstract
The approaches to quantitatively assessing the health risks of chemical exposure have not changed appreciably in the past 50 to 80 years, the focus remaining on high-dose studies that measure adverse outcomes in homogeneous animal populations. This expensive, low-throughput approach relies on conservative extrapolations to relate animal studies to much lower-dose human exposures and is of questionable relevance to predicting risks to humans at their typical low exposures. It makes little use of a mechanistic understanding of the mode of action by which chemicals perturb biological processes in human cells and tissues. An alternative vision, proposed by the U.S. National Research Council (NRC) report Toxicity Testing in the 21(st) Century: A Vision and a Strategy, called for moving away from traditional high-dose animal studies to an approach based on perturbation of cellular responses using well-designed in vitro assays. Central to this vision are (a) "toxicity pathways" (the innate cellular pathways that may be perturbed by chemicals) and (b) the determination of chemical concentration ranges where those perturbations are likely to be excessive, thereby leading to adverse health effects if present for a prolonged duration in an intact organism. In this paper we briefly review the original NRC report and responses to that report over the past 3 years, and discuss how the change in testing might be achieved in the U.S. and in the European Union (EU). EU initiatives in developing alternatives to animal testing of cosmetic ingredients have run very much in parallel with the NRC report. Moving from current practice to the NRC vision would require using prototype toxicity pathways to develop case studies showing the new vision in action. In this vein, we also discuss how the proposed strategy for toxicity testing might be applied to the toxicity pathways associated with DNA damage and repair.
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Affiliation(s)
- Sudin Bhattacharya
- Program in Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina, United States of America
| | - Qiang Zhang
- Program in Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina, United States of America
| | - Paul L. Carmichael
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedford, United Kingdom
| | - Kim Boekelheide
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, United States of America
| | - Melvin E. Andersen
- Program in Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina, United States of America
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Krewski D, Westphal M, Al-Zoughool M, Croteau MC, Andersen ME. New Directions in Toxicity Testing. Annu Rev Public Health 2011; 32:161-78. [DOI: 10.1146/annurev-publhealth-031210-101153] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Daniel Krewski
- McLaughlin Center for Population Health Risk Assessment, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5; , , ,
| | - Margit Westphal
- McLaughlin Center for Population Health Risk Assessment, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5; , , ,
| | - Mustafa Al-Zoughool
- McLaughlin Center for Population Health Risk Assessment, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5; , , ,
| | - Maxine C. Croteau
- McLaughlin Center for Population Health Risk Assessment, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5; , , ,
| | - Melvin E. Andersen
- Program in Chemical Safety Sciences, Hamner Institutes for Health Sciences, Research Triangle Park, North Carolina 27709, USA;
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