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2 The National Library of Medicine's Toxicology and Environmental Health Information Program In 1966, at a time of increased concern over the potential health effects of chemicals, the President's Science Advisory Committee examined the state of information in the growing science of toxicology and concluded that ''there exists an urgent need for a much more coordinated and more complete computer based file of toxicological information than any currently available and, further, that access to this file must be more generally available to all those legimately needing such information" (PSAC, 1966). That recommendation led to the establishment of the Toxicology Information Program (TIP) at the National Library of Medicine (NLM), which was retitled in 1994 as the Toxicology and Environmental Health Information Program (TEHIP) to more accurately reflect the scope of the program. The TEHIP program currently encompasses 16 databases offering a wide range of toxicology and environmental health information of importance to health professionals, the general public, scientists, and policymakers. This chapter provides a brief overview of NLM and the Division of Specialized Information Services (SIS), which oversees the TEHIP program. To inform readers unfamiliar with the breadth and depth of the TEHIP program's information resources, the main focus of this chapter is a description of the TEHIP program and of each of the TEHIP databases. The chapters that follow provide an assessment of the TEHIP program and address the toxicology and environmental health information needs of health professionals. For definitions of the acronyms refer to the glossary included at the end of the report.
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NATIONAL LIBRARY OF MEDICINE Begun in the early 1800s as a part of the Office of the Surgeon General of the Army, NLM has expanded its mission and scope to become one of the country's three national libraries1 and the primary collector of medical information (Miles, 1982). NLM's collection exceeds 5 million books, journals, and audiovisuals on health and medicine. The library also provides access to more than 40 online databases through its Medical Literature Analysis and Retrieval System (MEDLARS) (NLM, 1995). One of NLM's most well-known achievements is the bibliographic database MEDLINE, which is internationally respected as a source of citations and abstracts to the world's medical literature. Approximately 300,000 citations are added to the MEDLINE database annually. The Lister Hill National Center for Biomedical Communications and the National Center for Biotechnology Information are the research and development arms of NLM. Through these centers, NLM conducts a range of intramural and extramural research to explore new technologies in the fields of medicine, library science, computer science, and informatics. The National Library of Medicine Act of 1956 (Public Law 84-941) broadly mandated that NLM collect and organize health sciences information "to assist the advancement of medical and related sciences, and to aid the dissemination and exchange of scientific and other information important to the progress of medicine and to public health" (NLM, 1986). The library works with the 4,500 health science libraries of the National Network of Libraries of Medicine (NN/LM) and the eight Regional Medical Libraries (covering all geographic regions of the United States) to provide health professionals and other interested individuals with access to biomedical information. More than 3 million interlibrary loan requests are filled annually by NN/LM. Organization and Funding NLM is organized into six divisions (Figure 2.1), the largest of which is Library Operations, responsible for fundamental library services including literature collection, indexing, and cataloging. In fiscal year (FY) 1995, NLM employed 586 full-time equivalent (FTE) personnel. 1 The Library of Congress and the National Agricultural Library are the other national libraries.
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FIGURE 2.1 National Library of Medicine organizational chart. SOURCE: NLM, 1995.
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The majority of NLM's funding comes from its federal budget appropriation, which in FY 1995 was $128 million. Additionally, NLM receives reimbursements for projects with other agencies ($12.9 million in FY 1995). Although user fees are charged for searching the NLM database system,2 these fees do not supplement the NLM budget. Appropriated funds are used to build and maintain the MEDLARS databases, and user fees cover only the added costs associated with accessing this information (e.g., telecommunications charges) (NLM, 1996b,c). MEDLARS In the early 1960s, NLM applied emerging computer technologies to establish MEDLARS, which was used to produce bibliographic publications including Index Medicus and to conduct individual literature searches for health professionals (Miles, 1982). Since then MEDLARS has grown to encompass more than 40 bibliographic and factual databases, of which the most well-known and most often searched is the bibliographic database MEDLINE. In 1995, more than 7.3 million searches were performed on the MEDLARS databases (NLM, 1996a). There are a number of specialized databases on MEDLARS including those pertaining to HIV/AIDS (e.g., AIDSLINE and AIDSDRUGS), bioethics (BIOETHICSLINE), and the history of medicine (HISTLINE). Additionally, the toxicology and environmental health databases discussed in this report are part of MEDLARS. Table 2.1 provides a timeline overview of some of the major events and changes occurring within the past 40 years in computer technology, in the emergence and response to environmental health issues, and in the development of NLM's online databases. MEDLARS databases reside on two separate computer subsystems. NLM's original retrieval system, ELHILL, was designed for bibliographic databases. As a result, in the early 1980s when the records of the TEHIP factual databases became too large for the ELHILL system, it was determined that a new system was needed. TOXNET was developed in 1985 and is the system of networked microcomputers used for database file building, updates, and online searching for most of the TEHIP databases (Van Camp, 1989). A gateway links the ELHILL and TOXNET systems, making the databases available for searching by all NLM users. 2 Fees are also charged for leasing NLM databases.
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TABLE 2.1 Timeline of Events and Changes in Computer Technology and Environmental Health Computer Technology and the MEDLARS Databases Environmental Health and the TEHIP Program NLM established 1956 Batch processing; computers adopted for data processing by corporations 1960s Punched card batches used to produce Cumulated Index Medicus 1961 1961 Society of Toxicology founded 1962 Publication of Rachel Carson's book Silent Spring MEDLARS introduced; requested searches were batch processed 1964 1965 IARC established by the World Health Organization 1966 Publication of the President's Science Advisory; Committee's report Handling of Toxicological Information 1967 NLM's TIP established Time-sharing (sharing of computer services by multiple users introduced) 1970s 1970 Occupational Safety and Health Act established NIOSH and OSHA Clean Air Act enacted Microprocessor developed; enabled the development of the personal computer 1971 MEDLINE introduced online ARPAnet, the precursor to the Internet, becomes operational 1972 1972 TOXLINE developed by NLM Clean Water Act enacted MEDLINE tapes leased to commercial vendors mid-1970s
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Computer Technology and the MEDLARS Databases Environmental Health and the TEHIP Program 1976 Toxic Substances Control Act (TSCA) enacted 1978 Toxicology Data Bank developed by NLM National Toxicology Program established Desktop computers 1980s 1980 Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) enacted; ATSDR established 1983 OSHA's Hazard Communication Standard, which covered employees in the manufacturing sector of industry, is enacted 1985 TOXNET developed Grateful Med developed by NLM 1986 1986 Superfund Amendments and Reauthorization Act (SARA) enacted 1987 OSHA's Hazard Communication Standard expanded to include employees in all industries 1988 IOM report Role of the Primary Care Physician in Occupational and Environmental Medicine published 1989 Toxic Chemical Release Inventory (TRI) online database
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Computer Technology and the MEDLARS Databases Environmental Health and the TEHIP Program University of Minnesota introduces Gopher which rapidly increases access to the Internet 1990 NSCA releases first version of the Web browser, Mosaic 1992 1993 NLM Long Rang Planning Panel report Improving Toxicology and Environmental Health Information Services is published Number of Internet hosts reaches 6 million 1995 1995 IOM reports Environmental Medicine and Nursing, Health, and the Environment published Internet Grateful Med developed by NLM 1996 1996 National Occupational Research Agenda established by NIOSH NOTE: ATSDR=Agency for Toxic Substances and Disease Registry; EPA=Environmental Protection Agency; IARC=International Agency for Research on Cancer; NIOSH=National Institute for Occupational Safety and Health; NLM=National Library of Medicine; NSCA=National Center for Supercomputing Applications; OSHA=Occupational Safety and Health Administration; TIP=Toxicology Information Program. SOURCES: Brooks et al. (1995), Campbell-Kelly and Aspray (1996), Kissman and Wexler (1985), Miles (1982), Netscape (1996), Rom (1992), Tesler (1991), Zenz et al. (1994). DIVISION OF SPECIALIZED INFORMATION SERVICES Since the 1960s, NLM has had a commitment to the collection and dissemination of toxicology and environmental health information. The Specialized Information Services (SIS) Division of NLM is responsible for the TEHIP program in addition to its responsibilities for the AIDS-related databases (AIDS-LINE, AIDSTRIALS, and AIDSDRUGS) and other designated activities, including outreach programs. There are 34 FTE personnel working in SIS, making it the third smallest of the NLM divisions (NLM, 1995). SIS is organized into two branches, Biomed
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ical Information Services and Biomedical Files Implementation. Personnel in both branches work on the TEHIP program, and many have responsibilities beyond TEHIP. TOXICOLOGY AND ENVIRONMENTAL HEALTH INFORMATION PROGRAM Mission and History The 1966 President's Science Advisory Committee report Handling of Toxicological Information provided the impetus for the development of the Toxicology Information Program (TIP) at NLM (PSAC, 1966). This program began in 1967 with the anticipation of annual funding of several million dollars and staffing of 40 FTEs. However, funding and staffing never reached these anticipated levels. Instead, over the next several years the budgets for TIP were approximately $1 million annually and staffing levels remained at 10 to 18 people (Miles, 1982; NLM, 1993). TIP undertook a variety of projects, including answering reference queries from the biomedical community. Because staff levels at TIP remained lower than anticipated, NLM initiated an interagency agreement in 1972 with the Atomic Energy Commission to establish a Toxicology Information Response Center at Oak Ridge National Laboratory (ORNL) to handle the reference inquiries (NLM, 1993).3 Additionally, TIP produced numerous publications including the Pesticides Abstracts series—a joint project with the Environmental Protection Agency (EPA). The primary focus of TIP was the development of online databases, beginning with the TOXLINE database in 1972 (Kissman and Wexler, 1985). TOXLINE was designed as a comprehensive bibliographic resource for scientific literature on toxicology. As described below, TIP developed other databases to meet the needs of users searching for information on chemicals, including the dictionary files CHEMLINE and ChemID and the Hazardous Substances Data Bank (HSDB), an encyclopedic factual database originally developed as the Toxicology Data Bank. Throughout the program's 29-year history, other databases have been added, many of which originate in other federal agencies, including EPA, the National Cancer Institute (NCI), and the National Institute for Occupational Safety and Health (NIOSH). These databases have been added to the NLM system primarily in response to legislative mandates or because of the agency's interest in making its databases accessible to a wider audience. For example, the 3 This center continues to operate as an independant function of ORNL, with referrals made to it by NLM staff but without NLM funding.
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Superfund Amendments and Reauthorization Act of 1986 (SARA) mandated the collection and electronic dissemination of information on the annual release of chemicals into the environment by industrial facilities. As a result, EPA developed the Toxic Chemical Release Inventory database (TRI) and has disseminated the TRI database through NLM since 1989 (beginning with data submitted for TRI87, the first of these annual compilations). The Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) mandated the establishment of the Agency for Toxic Substances and Disease Registry (ATSDR) and specified that ATSDR maintain an inventory of the health effects of toxic substances. This legislation led to collaborative efforts between NLM and ATSDR in the expansion of what had been the Toxicology Data Bank to become the HSDB. Thus, the evolution of NLM's TEHIP program has been the result of both internal NLM commitments to developing toxicology and environmental health information resources and the interests of other federal agencies in fulfilling their missions and legislative mandates. In early 1994, following the recommendations of the NLM Long Range Planning Panel (NLM, 1993), the program's focus on environmental health information was made more explicit by renaming the program as the Toxicology and Environmental Health Information Program (TEHIP). The mission of the TEHIP program is to: provide selected core toxicology and environmental health information resources and services, facilitate access to national and international toxicology and environmental health information resources, and strengthen the information infrastructure of toxicology and environmental health (NLM, 1996d). The TEHIP program encompasses the 16 databases described below. It also offers other services and programs and performs extensive outreach efforts (see Chapter 5). Other aspects of the TEHIP program are addressed throughout the report. Funding As with NLM as a whole, the TEHIP program receives funds from two sources: those appropriated to NLM by the U. S. Congress and reimbursements from other agencies of the federal government. When the figures are adjusted for inflation, it can be seen that the budgeted funding for the TEHIP program has remained relatively constant over the past 29 years (in FY 1994, the TEHIP program's appropriated budget in current dollars was approximately $7.4 million [NLM, 1995]; Figure 2.2). However, TEHIP program reimbursements
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FIGURE 2.2 TEHIP program budget (constant dollars). from other agencies have fluctuated. Reimbursement funding is the result of collaborative projects with other federal agencies. Recently, the TEHIP program's financial reimbursements from other agencies have dropped significantly.4 In FY 1992, the TEHIP program's total reimbursable budget from other agencies was $2.45 million, whereas in FY 1993 the reimbursable budget dropped by approximately 50 percent to $1.27 million. Since 1993, the reimbursable budget has remained relatively level (the FY 1995 reimbursable budget was $1.23 million). 4 The reimbursable funds from the National Technical Information Service (NTIS) and ATSDR had the largest percentage decreases in the 1990s. Decreases in NTIS funds resulted from changes in NLM policy on how NTIS funds could be used for NLM projects. During the same time period, ATSDR developed its own in-house information resources (e.g., the HazDat database) and had less need to fulfill its mission by supporting information resources managed by other agencies such as NLM.
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TEHIP DATABASES The TEHIP program has 16 online databases (Table 2.2). These databases originate in several different federal agencies, a fact that has complicated attempts to standardize the databases and improve access. One of the features of the TEHIP databases unfamiliar to many users is the inclusion of both bibliographic and factual databases.5 Bibliographic databases are fairly standard in format and are organized to have one record per article citation (Figure 2.3). Each record includes the reference information needed to identify a journal article or other document (e.g., author, title, source, volume, and page numbers) and an abstract if one is available. To enhance the precision of online searching, Medical Subject Headings (MeSH) indexing terms are often included in NLM bibliographic records (Lowe and Barnett, 1994). Many health professionals are familiar with MeSH from their searches of MEDLINE. MeSH is a controlled vocabulary that is used to describe the subject content of the journal article. FIGURE 2.3 Organization of the TEHIP databases. 5 Bibliographic databases contain citations (and often abstracts) to the scientific literature; searchers must go to another source to obtain the full text of the cited article (Siegel et al., 1990). Factual databases contain actual data (e.g., a chemical’s physical and toxic properties) excerpted for inclusion in the database and usually provide a citation to the original source of the information.
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culating and statistical functions (e.g., average, standard deviation, mean, median, and mode). TRIFACTS A companion database to TRI is TRIFACTS, a factual database with information on the health effects, ecological effects, safety, and handling of the more than 300 TRI chemicals. The information in TRIFACTS is intended to provide the lay person with summary information on the TRI chemicals. When the searcher logs onto TRIFACTS, he or she is informed that TRIFACTS summaries ''should be supplemented with technical literature to answer in-depth questions." TRIFACTS summaries are adapted from the State of New Jersey Hazardous Substance Fact Sheets. The Fact Sheets were originally mandated by New Jersey's Worker and Community Right to Know Act and were developed for all chemicals on New Jersey's Right to Know Hazardous Substance List. EPA, through an agreement with the State of New Jersey, adapted the Fact Sheets for use as an online database and added EPA ecological data to the file. The TRIFACTS database was added to the TOXNET system in 1992. Organization and Content The TRIFACTS database has one record per chemical for most all of the over 300-plus TRI chemicals. Within each record the major categories of data are substance identification (including CAS Registry Number), chemical and physical properties, and safety and handling (including recommendations on personal protective equipment and clothing; the DoT Emergency Guidelines for firefighters, police, or emergency workers; and the National Fire Protection Association's Hazard Classification of flammability). Another major category of data includes summaries of the chemical's human toxicity and biomedical effects (Box 2.3). Information is included on emergency medical treatment procedures and acute and chronic (including cancer and reproductive) effects of the chemical on humans. Additionally, TRIFACTS provides ecological information (acute and chronic effects on aquatic and terrestrial life) and summaries of the exposure standards and regulations (including OHSA standards and NIOSH recommendations).
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BOX 2.3 Excerpt from the TRIFACTS Record on Toluene NAME Toluene RN 108-88-3 ACUTE The following acute (short term) health effects may occur immediately or shortly after exposure to toluene: Exposure can irritate the nose, throat, and eyes. Higher levels can cause you to feel dizzy, lightheaded, and to pass out. Death can occur. Lower levels may cause trouble concentrating, headaches, and slowed reflexes. Directory Of Information Resources Online The DIRLINE (Directory of Information Resources Online) database is unique among the TEHIP databases in providing directory information that not only covers the fields of toxicology and environmental health but also encompasses information resources throughout all fields of health and biomedicine. Descriptions and contact information for more than 17,000 biomedical and health-related organizations, databases, software programs, and other information resources are available through DIRLINE. This database was developed by SIS staff to provide an alternate source for answering information requests and was designed to be used by health professionals, information specialists, and the general public (NLM, 1994). Organization and Content The content of the DIRLINE database is merged from the following sources of directory information: Centers for Disease Control and Prevention National AIDS Clearinghouse Directory of Biotechnology Information Resources Health Services Research Information (National Information Center for Health Services Research) Maternal and Child Health Information (produced by the National Center for Education in Maternal and Child Health) Maternal and Child Health Information (produced by the National Center for Education in Maternal and Child Health) National Institutes of Health Research Resources NLM (list of organizations developed by the Library of Congress) NLM History of Medicine Division
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ODPHP Health Information Center Databases (sponsored by the Office of Disease Prevention and Health Promotion, U.S. Department of Health and Human Services) Poison Control Centers (data provided by the American Association of Poison Control Centers) Regional Alcohol and Drug Awareness Resource Network (produced by the National Clearinghouse on Alcohol and Drug Information) Self-Help Clearinghouses (produced in collaboration with the Surgeon General's Initiative in Self-Help and Public Health) Each DIRLINE record provides information on one information resource (Box 2.4). DIRLINE records include contact information (including address and telephone number), a summary description of the resource, and MeSH terms. Because of the multiple sources making up the DIRLINE database, duplicate records may be included. BOX 2.4 DIRLINE Record for the Association of Occupational and Environmental Clinics SI NLM/30011 NA Association of Occupational and Environmental Clinics AC AOEC AD 1010 Vermont Ave., NW, Suite 513, Washington, DC 20005 TEL (202) 347-4976 TEL (202) 347-4950 (FAX) AB The AOEC was established in 1987 to enhance the practice of occupational and environmental medicine through information sharing, education, and research. The growing member network now includes 39 clinics, and over 230 individuals. The AOEC aids in identifying, reporting, and preventing occupational and environmental health hazards and their effects. It encourages provision of high quality clinical services for people with work or environmentally related health problems. Its members receive reports based on databases being developed by AOEC, and on other AOEC research and conferences. The AOEC answers inquiries and holds workshops and seminars on Multiple Chemical Sensitivity (MCS). It acts as a resource for patient referrals for ATSDR, NIOSH, and others. NOTE: SI=Secondary Source ID; NA=Name; AC=Acronym; AD=Address; TEL=Telephone Number; and AB=Abstract. Review and Updates DIRLINE is provided free of charge as part of NLM's efforts to increase the availability of HIV/AIDS-related information to the scientific community
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and the general public. Access to DIRLINE does not require an NLM user code since DIRLINE is available through NLM's Locator Internet site (telnet locator.nlm.nih.gov) in addition to its availability as part of MEDLARS (NLM, 1995). DIRLINE is updated quarterly. TEHIP BIBLIOGRAPHIC DATABASES Many health professionals are familiar with NLM's bibliographic databases, particularly MEDLINE. Six of the TEHIP databases are bibliographic and provide references to the vast range of toxicology and environmental health literature. Obtaining the full text of the journal article or document may require using a variety of mechanisms. For toxicology and environmental health citations listed in MEDLINE, the full text document can be ordered through NLM's online ordering system, LOANSOME DOC. However, retrieving the full text of other citations may require utilizing other scientific libraries and resources. TOXLINE/TOXLIT A great diversity of scientific disciplines is involved in the fields of toxicology and environmental health. As a result, the scientific literature is dispersed among numerous journals and is indexed in a variety of sources. In 1972, NLM developed TOXLINE with the goal of having a single bibliographic database that would cover the field of toxicology (Kissman and Wexler, 1985). TOXLINE was designed to incorporate the relevant records from other indexing and abstracting sources and originally was composed of records from Index Medicus, Biological Abstracts, Chemical Abstracts, and International Pharmaceutical Abstracts. As shown in Table 2.4, the bibliographic records in TOXLINE are drawn from 18 sources; additionally, the companion file, TOXLIT, provides access to records from certain royalty sources, currently only Chemical Abstracts (see Chapter 6 for discussion of costs). Records from the 18 subfiles are not significantly altered or enhanced before being imported into TOXLINE. As a result, there is no single controlled vocabulary, and searchers must use a number of synonyms and similar expressions to search TOXLINE comprehensively. Additionally, the secondary sources that make up TOXLINE overlap to some extent in their coverage (e.g., MEDLINE, BIOSIS, and Developmental and Reproductive Toxicology [DART]) and may result in duplicate, although not identical, citations in TOXLINE (NLM, 1994).
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TABLE 2.4 TOXLINE Subfiles TOXLINE Subfile Subfile Description Aneuploidy Collection of bibliographic citations prepared by EMIC on numerical chromosomal abnormalities Developmental and Reproductive Toxicology (DART)a DART database on teratology and many aspects of reproductive toxicology Environmental Mutagen Information Centera EMIC database on substances tested for genotoxic activity Environmental Teratology Information Centera, b ETICBACK database covering the 1950–1989 teratology literature Epidemiology Information Systemb Epidemiology Information System database, developed by FDA's Center for Food Safety; citations cover literature published from 1940 to 1988 on the distribution and health effects of food contaminants Federal Research in Progress (FEDRIP) Subset of the FEDRIP database produced by NTIS and describing current federal research and development projects Hazardous Materials Technical Center (HMTC)b HMTC Abstract Bulletin on hazardous wastes, published by the Department of Army's Hazardous Materials Technical Center International Labour Office CIS Abstracts; toxicology-related material produced by the International Labour Office's International Occupational Safety and Health Information Centre International Pharmaceutical Abstracts (IPA) Subset of the IPA database on development and use of drugs; produced by the American Society of Health System Pharmacists NIOSHTIC Subset of the NIOSH's NIOSHTIC database on occupational safety and health literature Pesticides Abstractsb EPA publication on the epidemiological effects of pesticides; the publication was terminated in 1981 Poisonous Plants Bibliographyb Pre-1976 citations to literature on poisonous plants
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TOXLINE Subfile Subfile Description RISKLINE RISKLINE database developed by the National Chemicals Inspectorate in Sweden covers literature in toxicology and ecotoxicology Toxic Substances Control Act Test Submissions Reports of health and safety studies on certain chemicals submitted by industry to EPA Toxicity Bibliography (TOXBIB) Subset of the NLM's MEDLINE file, created monthly from SDILINE, the most recent month of MEDLINE Toxicological Aspects of Environmental Health (BIOSIS) Subset of the BIOSIS database (Biological Abstracts and Biological Abstracts/Reports, Reviews, and Meeting Abstracts) describing the health effects of chemical substances Toxicology Document and Data Depository Subset of the National Institutes of Health CRISP (Computer Retrieval of Information on Scientific Projects) database containing information on ongoing research in toxicology and related topics Toxicology Research Projects Subset of the NTIS Government Reports and Announcements database containing government publications on toxicology and related topics a Separate database also available via the TOXNET system. b Closed file. Records are no longer added to TOXLINE from these subsets. Organization and Content Because of the size of the database files (TOXLINE and TOXLIT files contain more than 4 million records), the pre-1981 records from TOXLINE and TOXLIT (which primarily cover the literature from 1965 to 1980) have been put into separate databases (TOXLINE65 and TOXLIT65). All four files (TOXLINE, TOXLINE65, TOXLIT, and TOXLIT65) are organized as traditional bibliographic databases with fields for basic bibliographic information including author, title, source, language, publication type, and abstract (when available). MeSH indexing terms are available only for the TOXBIB, BIOSIS, and DART subfiles of TOXLINE; additionally, the keyword field provides access to the indexing terms used by the subfile producer (e.g., FEDRIP). All of the indexing terms are used, along with terms from other fields, to provide text word searching capabilities. The CAS Registry Number is found in many of the TOXLINE records.
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Additionally, there are fields for specialized information to accommodate the information from the various subfiles (e.g., the Award Type field is used in the Toxicology Research Projects and FEDRIP subfiles to indicate whether the research project is intramural, contract, fellowship, or grant). Review and Updates TOXLINE and TOXLIT are updated monthly, with new records added from various subfiles. More than 140,000 records are added annually and the file is rebuilt each year to provide updated MeSH indexing. Developmental and Reproductive Toxicology Two bibliographic databases provide citations and abstracts to the scientific literature on teratology and developmental and reproductive toxicology. The ETICBACK (Environmental Teratology Information Center Backfile) database was produced by ORNL and covers the teratology literature from 1950 to 1989. A decision to expand the database to more fully cover the developmental and reproductive toxicology literature resulted in the closing of the ETIC file and the introduction of the DART database, which covers literature from 1989 to the present. Funding constraints, however, have prevented the comprehensive coverage of the scientific literature on lactation effects and on some aspects of male and female reproductive toxicology. Organization and Content Both DART and ETICBACK are bibliographic databases and provide searchable fields for basic bibliographic information including author, source, language, publication type, and, when available, the abstract. Substance identification fields in both databases provide searchable access to the CAS Registry Number and other identification information. MeSH terms have been added to the DART records, although some of the MeSH searching commands (e.g., explode or pre-explode) are not yet available in the TOXNET system. More than 60 percent of DART records come from MEDLINE; the others are identified by screening the literature not covered by MEDLINE (including meeting abstracts and government reports) (NLM, 1994). ETICBACK records include a number of specialized fields including assay method, experimental conditions, and maternal effects. Both databases currently receive or have received funding from National Institute of Environmental Health Sciences (NIEHS), EPA, NLM,
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and the Food and Drug Administration's National Center for Toxicological Research. Review and Updates ETICBACK is now a closed file, meaning that no new records are being added to the file. DART is updated monthly and is developed and maintained by NLM, with additions and deletions to the database made as necessary. Each month a search profile is run against the SDILINE database (a subset of the MEDLINE database containing only the most recent month's input into MEDLINE), and relevant records are added to DART. Additionally, relevant sources not indexed by MEDLINE are added. Environmental Mutagen Information Center EMIC and its backfile, EMICBACK, cover the scientific literature on genetic toxicity testing. In the late 1960s increased public and scientific concern about the mutagenic actions of chemicals led to the establishment of the Environmental Mutagen Information Center (EMIC) at ORNL (Wassom and Lu, 1992). One of the major functions of the Center since its inception has been the collection and organization of the scientific literature on chemical, biologic, and physical agents that have been tested for genetic toxicity. The result is the EMIC database, which was originally produced by ORNL and which is now managed by NLM. Support for EMIC is provided by EPA and NIEHS. Organization and Content Similarly to TOXLINE, EMIC has been separated into two bibliographic database files. The EMICBACK file covers the pre-1950 through 1991 literature, and the EMIC file includes the literature published since 1991. The two files contain more than 88,000 citations to the genetic toxicology literature, which can also be accessed as the EMIC subfile of the TOXLINE database. In addition to the bibliographic fields (e.g., author, title, source, and language), EMIC and EMICBACK contain a number of specialized fields regarding the assay and the study. These fields include keywords describing the test organism, tissue cultured, type of assay, and experimental conditions. EMIC records also contain fields identifying the substances involved in the test including the names of the test, the inducer, and the control agents. As described above, EMIC contains the records of sources used in EPA's GENE-TOX program, including the panel reports of the GENE-TOX reviewers.
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Review and Updates EMIC records are selected and indexed by ORNL. The EMICBACK file is closed (no new records will be added), and the EMIC file is updated monthly. Approximately 3,000 records are added to EMIC each year. CONCLUSIONS Although this chapter presents only an overview of each of the TEHIP databases, it is evident that there is a wealth of information available for use by health professionals, researchers, industry, policymakers, and the general public. What is also evident is the complexity of the TEHIP program—a complexity that results from the number of databases, the disparate scope and content of the databases, the diverse sources of information, and the variations in the type of information provided. The following chapters examine these issues and provide the committee's recommendations for facilitating health professionals' use of toxicology and environmental health information resources. REFERENCES Auletta AE, Brown M, Wassom JS, Cimino MC. 1991. Current status of the Gene-Tox Program. Environmental Health Perspectives 96:33–36. Bronson RJ. 1991. Toxic Chemical Release Inventory information. Medical Reference Services Quarterly 10(1):17–34. Brooks SM, Gochfeld M, Jackson RJ, Herzstein J, Schenker MB, eds. 1995. Environmental Medicine. St. Louis: Mosby. Campbell-Kelly M, Aspray W. 1996. Computer: A History of the Information Machine. New York: Basic Books. Kissman HM, Wexler P. 1985. Toxicology information systems: A historical perspective. Journal of Chemical Information and Computer Sciences 25:212–217. Lowe HJ, Barnett GO. 1994. Understanding and using the Medical Subject Headings (MeSH) vocabulary to perform literature searches. Journal of the American Medical Association 271(14):1103–1108. Lu P-Y, Wassom JS. 1992. Risk assessment and toxicology databases for health effects assessment. In: U.S. Environmental Protection Agency, Oak Ridge National Laboratory (ORNL). Proceedings of the Symposium on the Access and Use of Information Resources in Assessing Health Risks from Chemical Exposure. Oak Ridge, TN: ORNL. Miles WD. 1982. A History of the National Library of Medicine. NIH Publication No. 85-1904. Bethesda, MD: National Institutes of Health. Netscape. 1996. Internet time line. Inside Netscape Navigator 1(4):8–9. NLM (National Library of Medicine). 1986. Building and Organizing the Library's Collection. Long Range Plan, Report of Panel 1. Bethesda, MD: NLM.
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