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Water: Microbial

Thesaurus of Terms Used in Microbial Risk Assessment - Chapter One: Introduction


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The United States Environmental Protection Agency’s (EPA) Office of Water has developed this Thesaurus of Microbiological Risk Assessment (MRA) Terms because it is important for risk assessors, managers, and communicators to have available and to use common, understandable terms and definitions for the various facets of the MRA process. This Thesaurus is a collection of definitions of terms that may be relevant for microbial risk assessment (MRA). It should help risk assessors, managers, and communicators become aware of various definitions so that they can better communicate with each other and avoid misunderstandings. It should also help increase transparency and contribute to a common understanding of the MRA process and presentation of MRA results.

Currently, various program offices within EPA, as well as other Federal Agencies (e.g., Food and Drug Administration [FDA] and United States Department of Agriculture [USDA]) and International Agencies (e.g., World Health Organization [WHO] and Food and Agricultural Organization [FAO]), utilize terms often unique to the activities or MRA applications for that specific agency. Different Agencies may also have different operating definitions for the same term. This Thesaurus seeks to identify the terms that have the most potential to cause confusion due to varying uses for terms.

1.1 Background and Scope

Risk assessment is an important tool used by a variety of disciplines or fields of study. Because the different fields of risk assessment use their own methods and terms and also borrow from other scientific disciplines, much of the nomenclature is broadly used, but narrowly defined within a field. In addition, similar concepts may go by different names in different fields. For example, in ecological risk assessment a stressor interacts with a receptor, whereas in chemical risk assessment for human health scenarios, toxicants (or toxins) interact with humans through various exposure routes. In MRA, hazards interact with hosts either through “primary” and “secondary” exposures. Pointing out these differences is not meant to suggest that these differences are inappropriate, but to help designers and users of risk assessment understand that these differences exist so that as the science of risk assessment evolves, it is less likely that any given term is adopted for multiple uses.

The major fields of risk assessment that contributed terms and definitions to this Thesaurus include:

  • air toxics risk assessment (risks to humans from inhaled toxins)
  • carcinogen risk assessment (risks to humans from mainly chemical carcinogens)
  • ecological risk assessment (risks to wildlife and ecosystems)
  • environmental risk assessment (risks to the environment)
  • food safety risk assessment (risks to humans from consumption of food)
  • microbial risk assessment (risks to humans from microbial pathogens)
  • nuclear radiation risk assessment (risks to humans from radiation exposure)
  • water safety risk assessment (risks to humans from drinking water, recreation, or other water uses)

Because risk assessment is multi-disciplinary, terms and definitions from contributing disciplines are often adopted. Term preference is often determined by the risk assessor’s educational background and areas of expertise. Disciplines that contribute to risk assessment terminology include, but are not limited to: biology, chemistry, computer science, economics, epidemiology, law, mathematics/statistics, medicine (clinical), microbiology, pharmacology, philosophy, policy, toxicology and veterinary sciences. In addition, terms may be favored or disfavored by different government agencies. In many cases the terminology adopted by an agency comes from the legislations that enable that agency’s regulatory authorities. Risk assessors, managers, or communicators that are isolated in one agency’s working culture may not be familiar with how risk assessment terms are used in other agencies.

Terms are generally proposed and modified by mostly informal processes that involve communication between policy makers, risk assessors, industry, academia, the general public, and other stakeholders. One example of the process of creating a definition is when the definition of a term is presented in a draft guidance document and then commented on by stakeholders. In some cases, terms are included in statutes, so they have legal definitions within that context. One example is “safety factor” that is defined by statue for food additives, but has non-legal definitions in other contexts. More formal efforts for evaluating definitions are carried out by the Organisation for Economic Co-operation and Development (OECD) and the International Programme of Chemical Safety (IPCS), such as their joint project on the Harmonisation of Hazard/Risk Assessment Terminology (IPCS/OECD 2004) and the work of the IPCS Exposure Terminology Subcommittee (IPCS 2001).

This Thesaurus of terms and definitions has been compiled based upon existing risk assessment related documents prepared by various national and international entities having responsibilities for conducting, interpreting, or using risk assessments (especially related to microbiological risks). It is not intended to provide all terms and definitions that may be used for various science applications in all facets of microbiology, ecology, chemistry, biology, etc. The intent of this document is to capture those terms and defnintions which appear to have significant risk assessment applications as identified in existing documents. It should be noted that there also may be a few gaps in risk assessment related terms or definitions that were not provided by the various documents searched in the present effort.

This Thesaurus contains a few terms or definitions which are used in specific regulations; however, the bulk of relevant regulatory terms are not included because they have specific definitions that are context-dependent. Any terms identified here as regulatory definitions should not be considered as the definitive source and should be further examined in the referenced regulatory document. It is important for anyone using this Thesaurus to know that in certain regulatory uses of terms there may be a specific context for the definition and additional background information for its uses may be provided in that regulatory document that are not covered here. Because there is an authoritative source for the definitions of regulatory and statutory terms (they can be found in the Code of Federal Regualtions or the United States Code) they are not covered comprehensively in this Thesaurus.

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1.2 Sources Consulted

Numerous (mostly online) glossaries, lists of terms and definitions, and publications were consulted during the development of the Thesaurus. Throughout the Thesaurus, primary (and in some cases secondary) sources for each definition are indicated. The primary sources consulted are briefly described below. Complete references for all primary sources, including URLs (as available), are provided in the Reference section at the end of the Thesaurus.

EPA Sources

  • The EPA-International Life Sciences Institute (ILSI) Revised Framework for Microbial Risk Assessment (ILSI 2000) has been EPA Office of Water’s working MRA framework. For this thesaurus, the EPA-ILSI 2000 framework glossary as well as several terms included in the text, but not listed in the glossary, provided the basic list of terms. This is the only document for which definitions are taken from the main text as well as from the glossary.
  • EPA’s Integrated Risk Information System (IRIS) has an online glossary of terms (EPA 2003). IRIS is an electronic database containing information on human health effects that may result from exposure to various chemicals in the environment. IRIS was initially developed for EPA staff in response to a growing demand for consistent information on chemical substances for use in risk assessments, decision-making, and regulatory activities.
  • EPA is currently developing an air toxics risk assessment (ATRA) reference library for conducting air toxics analyses on facility and community scales. This effort will result in a three-volume library that provides information on the fundamental principles of risk-based assessment for air toxics and how to apply those principles in different settings, as well as strategies for reducing risk at the local level. Volume 1 (EPA 2004) discusses the overall air toxics risk assessment process and the basic technical tools needed to perform these analyses. The manual, which covers both human health and ecological analysis, also provides a basic overview of risk management and communication. Other tools (such as the public health assessment process) are described to give assessors, risk managers, and other stakeholders a more holistic understanding of the many issues that may come into play during air toxics risk assessment and reduction projects. An extensive glossary, which compiles definitions from many EPA sources is included. The disclaimer notes that definitions used therein are not official EPA definitions.
  • The EPA Exposure Factors Handbook (EPA1997a) provides summary statistical data on exposure factors necessary to assess human exposures to environmental contaminants. The glossary has terms that are related to exposure.
  • EPA’s Office of Wetlands, Oceans and Watersheds published Ecological Restoration: A Tool to Manage Stream Quality (EPA 1995a) with four objectives related to the Clean Water Act and stream restoration. Chapter 8 of this seminal report includes a glossary of ecological restoration-related terms that are relevant to this Thesaurus and which was last updated on August 18, 2003.
  • The EPA Guidelines for Ecological Risk Assessment (EPA 1998a) includes a glossary of terms. The EPA/ILSI 2000 framework is based on the basic risk assessment structure that is presented in that report.
  • EPA published Guidelines for Carcinogen Risk Assessment and Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens in March of 2005 (EPA 2005a). There are a few footnotes that provide definitions relevant to MRA.
  • The EPA Office of Communications, Education, and Public Affairs (OCEPA) maintains an online glossary called Terms of Environment, which defines in non-technical language the more commonly used environmental terms appearing in EPA publications, news releases, and other Agency documents available to the general public. The definitions do not constitute the Agency’s official use of terms and phrases for regulatory purposes. Although the printed version of the glossary was last revised in 1997, the website version from June 13, 2005 was used for this Thesaurus (EPA 2005b).
  • The National Health Environmental Effects Research Laboratory of EPA’s Office of Research and Development maintains an online Definitions of Terms within the Aquatic Resources Monitoring Web Site, which contains terms and definitions relevant to this Thesaurus and was lasted updated on July 7, 2005 (EPA 2005c).
  • EPA’s Technology Transfer Network Air Toxics Website includes an online Glossary of Health, Exposure, and Risk Assessment Terms and Definitions of Acronyms that is relevant to this Thesaurus and was last updated in February 2005 (EPA 2005d).
  • EPA’s online Pesticides Glossary was consulted for terms that are relevant to MRA. (EPA 2005e)
  • EPA Office of Water’s Draft Methodology for Deriving Microbial Ambient Water Quality Criteria for the Protection of Human Health was also used as a source for a few definitions. (EPA 2005f)

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Other U.S. Sources

  • The U.S. Centers for Disease Control and Prevention (CDC) provide and maintain an online Reproductive Health: Glossary that includes several medical, epidemiological, and risk assessment terms and definitions that are include in this Thesaurus. The CDC glossary was last updated on April 6, 2005 (CDC 2005).
  • The FDA, Center for Food Safety and Applied Nutrition (CFSAN) has published Initiation and Conduct of All ‘Major’ Risk Assessments within a Risk Analysis Framework: A Report by the CFSAN Risk Analysis Working Group (FDA 2002). The glossary of terms closely agrees with the international definitions put forward by the Codex Alimentarius Commission.
  • The FDA CFSAN provides the A to Z Comprehensive List of Terms (FDA 2001) as part of the online “Food Safety A to Z Reference Guide.” This list contains several terms and definitions that are relevant to this Thesaurus.
  • The Agency for Toxic Substances and Disease Registry (ATSDR) is an agency in the Department of Health and Human Services. ATSDR was created by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA, also known as Superfund) and is responsible for assessing health issues and supporting public health activities related to hazardous waste sites or other environmental releases of hazardous substances. An online glossary defines words used by ATSDR in communications with the public (ATSDR 2004).
  • Risk Assessment Information System (RAIS) is an internet-based resource for risk assessment tools and guidance. It is supported by the U.S. Department of Energy (DOE), Office of Environmental Management, and Oak Ridge Operations (ORO) Office through a contract with Bechtel Jacobs Company LLC. The Glossary of Useful Terms Found in Risk Assessment cites other sources that were used in this Thesaurus; therefore most of the RAIS terms are duplicative (RAIS 2004).
  • The U.S. Navy Environmental Health Center’s Environmental Programs Directorate has been the Navy’s risk communication expert since its inception in 1991. Their website, Risk Communication: Navy Health Operational and Environmental Issues, includes an online Glossary (Navy 2002) that includes a few terms and concise definitions related to risk communication that are included in this Thesaurus.
  • The website Navy Guidance for Conducting Ecological Risk Assessments includes an online Glossary (Navy 2003) that includes a few terms and definitions that are relevant to this Thesaurus.
  • The website for the Travis Air Force Base Environmental Restoration Program includes an online Glossary (TAFBERP 2005) from which one term and definition are included in this Thesaurus.
  • The U.S. Department of Transportation report Probabilistic Risk Analysis for Turnkey Construction: A Case Study; Final Report (USDOT 1996) includes a Glossary from which one term and definition are included in this Thesaurus.
  • The U.S. Nuclear Regulatory Commission provides and maintains an online Basic References: Glossary (USNRC 2005) from which one term and definition are included in this Thesaurus.
  • The U.S. National Institute of Standards and Technology provides and regularly maintains an online Dictionary of Algorithms and Data Structures (NIST 2005) that includes several terms and definitions related to statistical processes and modeling that are included in this Thesaurus.
  • The e-Handbook of Statistical Methods (NIST/SEMATECH 2005a) is an Internet-based book whose goal is to help scientists and engineers incorporate statistical methods into their work as efficiently as possible. It is intended to serve as a useful educational tool that will help users of statistical methods and consumers of statistical information better understand statistical procedures and their underlying assumptions and more clearly interpret scientific and engineering results stated in statistical terms. Several statistical terms and their definitions from this online book are included in their entirety or in abbreviated form in this Thesaurus. The book also includes a semi-independent online Glossary (NIST/SEMATECH 2005a), which contains several terms and definitions that are also included in this Thesaurus.
  • Managing Effective Risk Response: An Ecological Approach (MERREA) seeks to improve risk management by helping individuals and agencies to predict, inform, and manage the responses of the various stakeholders involved in any risk event more openly and effectively. Their website provides and maintains an extensive Glossary of Risk Management (MERREA 2005) which includes several terms and definitions that are included in this Thesaurus.
  • The National Library of Medicine’s National Information Center on Health Services Research and Health Care Technology provides an online glossary (NLM/NICHSR 2004) of clinical and statistical terms that are relevant to this Thesaurus.
  • The New York State Governor’s Office of Regulatory Reform’s Cost-Benefit Handbook: A Guide for New York State’ Regulatory Agencies (NYS 1998) includes a glossary of economic and risk assessment terms in Appendix A. Several of these terms and definitions are included in this Thesaurus.
  • The USDA Economic Research Service (ERS), maintains A Safe Food Supply Glossary on their website (USDA 2004). Terms from this glossary highlight how risk assessment can include economic factors.
  • The Rehabilitation Research and Training Center on Positive Behavior Support of the University of South Florida includes an online Glossary (RRTC-PBS 2003), which includes a few terms and definitions that are included in this Thesaurus.
  • Research Professor E. Bruce Brooks (Brooks 2001) of University of Massachusetts, Amherst, has provided an online glossary for Acquiring Statistics: Techniques and Concepts for Historians since 2001 that provides concise definitions for several statistical terms that are relevant to this Thesaurus.
  • The Society for Risk Analysis Committee for Definitions maintains an online Glossary of Risk Analysis Terms (SRA 2004) which has not been officially adopted or endorsed by SRA but is relevant to this Thesaurus.
  • MathWorld is a comprehensive and interactive mathematics encyclopedia intended for students, educators, math enthusiasts, and researchers and is continuously updated to include new material and incorporate new discoveries. Several mathematical and statistical terms and definitions from this website (Weisstein/MathWorld 2002. 2003, 2005a, b) are included in this Thesaurus.

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International Sources

  • Codex Alimentarius Commission was created by the FAO and WHO to develop food standards, guidelines and related texts such as codes of practice under the Joint FAO/WHO Food Standards Programme. Since its formation in 1963, Codex has been an internationally acknowledged source for terms and definitions used throughout food related policies. Water and food are related because both are intentionally consumed and can harbor pathogenic microorganisms, therefore MRA frameworks and tools developed for use in food media are very often applicable for water media. Included in this Thesaurus are terms from three Codex publications—the twelfth and thirteenth editions of the procedural manual, and Principles and Guidelines for the Conduct of Microbiological Risk Assessment (CAC 1999, 2002, 2003)
  • ILSI Europe has published a Concise Monograph Series, Principles of Risk Assessment of Food and Drinking Water Related to Human Health (ILSI 2001). This document is distinctly different from the EPA-ILSI framework mentioned above. The European publication follows the chemical risk assessment paradigm, whereas, the EPA-ILSI (2000) framework follows an environmental paradigm. Terms are from the glossary that is included in the monograph.
  • The Organisation for Economic Co-operation and Development (OECD), in a joint project with the International Programme of Chemical Safety (IPCS) on the Harmonisation of Hazard/Risk Assessment Terminology, has published a Description of Key Generic Terms Used in Chemical Hazard/Risk Assessment (IPCS/OECD 2004). The report includes a survey of 186 risk professionals from around the world and their ranking of various definitions for terms. The final output of this effort will be an annotated glossary of terms reflecting the situation that emerges from the responses to the survey. The comments that committee members submitted for different terms are included in the report and serve as a list of observations about the definitions. Some of the terms evaluated during the OECD project are included in this thesaurus.
  • The Food and Agricultural Organization of the United Nations (FAO) and the World Health Organization (WHO) have published Hazard Characterization for Pathogens in Food and Water Guidelines in their Microbiological Risk Assessment Series (FAO/WHO 2003a), which includes several definitions that are relevant to this Thesaurus.
  • The FAO and WHO published Assuring Food Safety and Quality: Guidelines for Strengthening National Food Control Systems to enable national authorities, particularly in developing countries, to improve their food control systems (FAO/WHO 2003b). Annex 1 of the report includes a Glossary with several terms and definitions that are relevant to MRA and this Thesaurus.
  • The online World Bank, Human Capital Development and Operations Policy Working Paper The Disability-Adjusted Life Year (DALY) Definition, Measurement and Potential Use (World Bank 2004), was cited directly to provide a definition for this important term.
  • The framework document, The Interaction Between Quantitative Microbial Risk Assessment and Risk Management in the Water Safety Plan (KIWA 2004), was prepared by Kiwa Water Research and the University of Delft (both of The Netherlands) in collaboration with the Institute of Infectious Disease Control (Sweden), Anjou Recherche (France), Veolia Water Partnership (UK), WRc-NSF (UK), Bonn University (Germany), Ondeo Services (France), University of East Anglia (UK), University of New South Wales (Australia), and Water Technology Centre (Germany). The framework is part of a larger research project called “MicroRisk: Scientific Basis for Managing Drinking Water Safety from Source to Tap,” that is co-financed by the European Commission (Contract EVK1-CT-2002-00123). Many terms from the framework glossary are included in this Thesaurus.
  • The Food Standards Agency (FSA) of the UK was created by an Act of Parliament in 2000 to be an independent food safety entity to protect public health and consumer interests in relation to food. Some definitions relevant for risk assessment from the FSA online glossary are included in this Thesaurus (FSA 2005).
  • The Australian Academy of Science (AAS) provides online versions of their periodic Nova reports that focus on the science behind a variety of technology and policy topics. One such report, entitled Good Prospects Ahead for Data Mining, includes a glossary of decision-making and networking terms and definitions that are relevant to this Thesaurus.
  • The Cooperative Research Centre for Water Quality and Treatment (CRCWQT) provides a national strategic research capacity for the Australian water industry. It also provides an online Glossary of Water-Related Terms (CRCWQT 2002) that includes several terms and definitions that are included in this Thesaurus.
  • The New Zealand Ministry for the Environment publication, Freshwater Microbiology Research Programme Report: Pathogen Occurrence and Human Health Risk Assessment Analysis, includes a glossary of terms (NZ 2002). Definitions for terms relevant to risk assessment are included in this Thesaurus.
  • Canada’s General Risk Assessment Framework for the Ontario Ministry of Agriculture and Food (OMAF 1997) has core terms that generally agree with the Codex definitions for the same terms; however, the Canadian definitions are included due to their slight variation.
  • The Department of Medical Oncology of the University of Newcastle upon Tyne (United Kingdom) provides and maintains an On-line Medical Dictionary as part of its CancerWeb Project (CancerWEB 2005).  Several definitions relevant for MRA from this online medical dictionary are included in this Thesaurus.
  • The European Society for Opinion and Marketing Research (ESOMAR) provides an online Glossary of Marketing Research Terms (ESOMAR 2001) which includes several terms and definitions that are relevant to this Thesaurus.

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