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Chemical Abstracts Service

National historic chemical landmark.

Dedicated June 14, 2007, at the Chemical Abstracts Service in Columbus, Ohio.

Commemorative Booklet (PDF)

The Chemical Abstracts Service, a division of the American Chemical Society, has provided the most comprehensive repository of research in chemistry and related sciences for over 100 years. CAS innovations have fueled chemical research through development of the CAS Registry SM and CAS databases which contain invaluable information for chemical scientists, including SciFinder ® and STN ® .

Early Chemical Abstracting in the United States

Growth of chemical abstracts, cas expansion: 1950’s and 1960’s, digital age and computer-enabled abstracting, the cas registry, online abstracting tools: stn, scifinder, and more, further reading, landmark designation and acknowledgments, cite this page.

The early history of chemical abstracting in the United States is intertwined with the Noyes family. In 1895, Arthur A. Noyes, a professor of physical chemistry at the Massachusetts Institute of Technology, began the Review of American Chemical Research (the Review ) as a supplement to MIT's Technology Quarterly . He began the Review because he believed American chemists were not receiving adequate credit in European publications for their accomplishments, and under his editorship, the Review published only abstracts of American chemical papers.

In 1897, the Review became part of the Journal of the American Chemical Society ( JACS ). Five years later, William A. Noyes, Sr. (Noyes), a distant cousin of Arthur A. Noyes, became editor of JACS and the Review . Noyes long believed that the American Chemical Society should publish a comprehensive and inclusive separate journal of abstracts. He worked diligently to persuade the Society to authorize an abstract journal, and in 1906, the ACS Council approved publication of Chemical Abstracts , with Noyes as editor. The first issue appeared in January 1907.

Chemical Abstracts was not the first publication to abstract chemical information. Scientific abstracts first appeared in primary journals, which published abstracts of work reported in other sources in addition to original research. One example was the Philosophical Transactions of the Royal Society. The first specifically chemical publication to include abstracts was Crell's Chemische Journal fÜr die Freunde der Naturlehre , which was published from 1778 to 1781. Other German publications appeared in the late 1700s as a forum for chemists to exchange information and research. French ( Annales de Chemie) and British ( Journal of the Chemical Society ) publications followed suit in the next century.

At the same time, publications specifically devoted to chemical abstracts began to appear. The most famous of these was Chemisches Zentralblatt , which debuted in 1830. It was published weekly under the editorship of Gustav Theodor Fechner. Chemisches Zentralblatt initially covered only German literature, and while it expanded its coverage in the early 20th century, the emphasis was always on German material. Chemisches Zentralblatt remained an important abstracting service until World War II. It was the emphasis on German chemistry that prompted the interest in an American abstract service.

Noyes served as editor of Chemical Abstracts for its first two years. At first, Noyes worked from his laboratory at the National Bureau of Standards in Washington, where he was chief chemist. He and Chemical Abstracts moved to the University of Illinois when Noyes became chair of the chemistry department there in 1907. Noyes’ contribution to the success of Chemical Abstracts cannot be exaggerated. Not only did he persuade ACS to sponsor an abstract journal, but he organized, planned and edited the publication while serving as ACS secretary and working full time. Many of the policies he implemented served Chemical Abstracts for decades.

One of Noyes's most important legacies was his insistence that Chemical Abstracts cover applied as well as theoretical chemistry. In the early 20th century the gulf between industrial and academic or theoretical chemists was wide and many of the latter thought that ACS, and its publications, should belong to "pure" chemists only with applied chemists shunted off to a separate organization. In England and Germany chemists split along these lines and in both countries distinct abstract journals existed. Chemical Abstracts pioneered in the merging of the interests of these two groups of chemists.

In 1909 Austin Patterson succeeded Noyes as editor, and the editorial offices moved to The Ohio State University (OSU) in Columbus at the invitation of William McPherson, head of the OSU Chemistry Department. Chemical Abstracts remained at Ohio State until 1965, when the Chemical Abstracts Service moved into its own building on a 50-acre site adjacent to the university.

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The mission of CAS is to be the world's leading provider of chemical information." — Robert J. Massie, President, CAS

(Quoted in Ross, Linda Romaine, "CAS Aims to Keep Customers by Improved Service, Pricing, Management," Chemical & Engineering News 72 (October 31, 1994): 20.)

The early history of Chemical Abstracts is the story of Evan J. Crane, who served as editor for 43 years. Crane succeeded John Miller, editor for a brief time in 1914 following Austin Patterson's resignation. Crane joined Chemical Abstracts in 1911 at the age of 22 as an associate editor; he became acting editor in 1915 after Miller’s resignation.

During Crane's stewardship, Chemical Abstracts grew from a fledgling operation into the trendsetter for scientific abstracting and indexing journals. Crane did this through some very difficult times—money was often so scarce that he dipped into his own small salary for business travel. Crane himself wrote that it was his "long-established policy to trim his budget sails as well as possible to fit the Society's current circumstances and then to keep within budget limits." During his tenure he did that, never exceeding the publication’s annual budget.

Crane said that "in times of financial difficulty, keeping within limits [was] accomplished principally by shortening abstracts rather than by failing to report all papers and patents containing new information of chemical interest. The history of Chemical Abstracts is in part a series of ups and down as far as length of abstracts is concerned, with most of the emphasis on 'downs.'" Crane's perseverance in the face of financial and other difficulties insured the success of Chemical Abstracts . He won many honors, including the Society's Priestley Medal, but perhaps Crane's greatest honor came in 1956 when he was named the first director of the renamed Chemical Abstracts Service (CAS), a new division of the American Chemical Society.

Under Crane's tutelage, Chemical Abstracts grew rapidly. In its first year of operation, 1907, the service published 12,000 abstracts. Half of those were on works published in Germany. The number of abstracts published rose almost every year after and the service soon claimed complete coverage of the chemical literature. Of course, the definition of "completeness" is itself abstract; as Crane wrote "completeness in an abstract journal is a somewhat indefinite goal never quite attained, but the whole history of Chemical Abstracts has been one of striving for complete coverage so that the user of this journal can have confidence in the thoroughness of his survey without searching elsewhere." He defined completeness as reporting all suitable papers and patents, insuring that each abstract is thorough to allow full indexing, and guaranteeing that the index contains all the useful information that a searcher needs.

Completeness meant, among other things, that the number of abstracts published each year soared. It was not until 1939—32 years after publishing began—that the number of abstracts published reached one million; it took eighteen years to generate the next million; eight years for the third million. In 2006, for the first time in one year, more than one million abstracts were added to the CAS databases.

Crane recognized early in his tenure that comprehensive and accurate indexes were necessary. Cursory author and subject indexes were provided from the beginning, but Crane undertook to release a thorough Chemical Abstracts Decennial Index in 1916, doing much of the work himself. This project prompted a search for a more thorough system of indexing. The solution was to devise a systematic index for compounds on the grounds that the absence of such a system would mean that references to compounds would be scattered throughout the index and related compounds would not be grouped together. The indexing system had an important influence on chemical nomenclature.

Over the years indexing assumed increased importance because of the volume of material being abstracted. An annual formula index was added in 1920. Other indexes were added: for example, numerical patent indexes and a keyword subject index. The amount of material abstracted became so large that in 1962 Chemical Abstracts began publishing Volume Indexes semiannually rather than annually.

Crane retired in 1958. He was replaced by Dale Baker, who became Director, while Charles Bernier was appointed Editor and Leonard Capell, CAS' nomenclature expert, was named Executive Consultant. The most important task facing these three men was to oversee CAS' transition from an ACS-supported service to a financially independent operation. In the beginning, ACS-member dues financed Chemical Abstracts and Society members could receive it free. In 1933 a small subscription fee was charged, as a supplement to the allocation from dues, a system that satisfied CAS' financial needs for a time.

After World War II, this financial arrangement proved inadequate. The rapid expansion of scientific publications—which meant more abstracts—coupled with post-War inflation forced CAS to look elsewhere for funding. For a time, industry was asked to make up the service's deficit. In 1955, the ACS Board of Directors stepped in and changed subscription prices with the aim that Chemical Abstracts should break even. Fees were raised so that, in the words of Board Chair Ernest Volwiler, Chemical Abstracts would become "a joint responsibility of the profession and of those governmental, industrial, and commercial organizations that have a direct stake in its availability."

The post-Crane leadership had a second problem to tackle—housing for a rapidly expanding organization. Since 1909, CAS had been housed on the OSU campus, first in a 15-by-30 foot room, then a room twice that size, and in 1928 in 1,600-square foot section of McPherson Chemistry Laboratory. In the 1950s, when CAS had a staff of 100, a building jointly financed by ACS and OSU was erected on campus to house the abstract service. In 1965—now with a staff of 300—CAS moved into a four-story, multi-million dollar building of its own on a 50-acre site adjacent to OSU's campus. Less than a decade later CAS added a second building.

Until the 1960s, Chemical Abstracts relied on volunteers for the bulk of its abstracting. In 1907, Chemical Abstracts utilized 129 volunteer chemists; by the mid-1960s the number of volunteers reached more than 3,200. Crane referred to some of the volunteers as "the iron men of CA [ Chemical Abstracts ]," and many served for decades, with thirteen volunteers abstracting for more than 50 years. Over the years the abstractors took on an international caste as chemists from 70 nations contributed entries. In the mid-1960s, CAS began to phase out its use of volunteers, and in 1994 it entirely ceased using volunteer abstractors.

The decline in use of volunteers corresponded to CAS' entry into the digital age. Baker and the rest of the CAS leadership understood the need to modernize procedures due to the vast increase in chemically-related published material. Older methods for producing abstracts did not suffice by the 1960s. On one level, this meant professionalizing of the staff; at another, it meant new ways of processing information.

CAS had been moving into the information age slowly. In 1955 it established a research and development department. In 1959 Baker hired G. Malcolm Dyson, an Englishman who had worked on an early linear notation system for representing chemical structures. It was Dyson—working part-time in Columbus from 1959 to 1963—who developed many of the cutting-edge innovations in information processing that CAS introduced in these years, starting with Chemical Titles in 1961. Chemical Titles was the first periodical to be organized, indexed and composed by computer, which meant greater publishing speed. The issue of Chemical Titles listing a given article often reached subscribers before the journal in which that article appeared.

CAS information needs began to drive the technology. For example, CAS required a composition system that did not yet exist. This problem was solved in 1967 when CAS acquired an IBM unit and then developed a software-based, computer-driven composition system for it. It was put to good use, and by 1970 all Chemical Abstracts indexes were being organized and composed by computer. Computerization meant considerable savings in staff time and costs. It also meant more precise data; in addition, staff no longer had to do the routine fact checking which could now be done by the computer. This freed staff for the more intellectual tasks of analyzing the primary chemical literature. For chemists, it meant ease and speed. Information seekers in the past might have to wait a day or more for a librarian to find the appropriate references (only to find sometimes that the references were not appropriate). With computers, the chemist could do his own searching and do it quickly and accurately.

CAS revenues sources shifted with computerization. In 1975 95% of CAS' revenues came from print services; only 5% from electronic sources. By the end of the 20th century, that had shifted to 19% of revenues from printed sources with 79% from electronic services (the remaining 2% came from consulting and other sources). In 2006 95% of CAS' revenue stream derived electronic sources with the remaining 5% from print and other services.

The mechanization of information yielded CAS' most significant and far-reaching innovation: The Chemical Registry System. G. Malcolm Dyson first suggested the idea of a registry in the late 1950s. With the increasing complexity and sheer numbers of substances appearing in the literature, CAS needed an alternative to chemical nomenclature as a basis for this registry.

Chemists have an advantage over many other scientists in being able to communicate by referring to chemical compounds through unambiguous and universally understood structural diagrams. These diagrams indicate a compound's chemical atoms, the bonds that connect them, and even the spatial arrangement of the atoms. But there was no good way to catalogue these structures that enabled easy retrieval. At CAS, every time a chemical compound was indexed it was copied by hand and then given a name, which may or may not have agreed with the name given it by its presumed discoverer. Was the compound really new? Had it been reported in the literature? Indexed by Chemical Abstracts ? The rapid increase in the number of named structures led to much confusion; some compounds were named over and over.

Clearly, CAS needed a system that recognized previously named structures and allowed for easy retrieval by CAS staff. In the early 1960s a solution was found when Harry Morgan of CAS developed an algorithm that generates a unique and unambiguous two-dimensional record of a substance's structure. The record could be read by a computer and was so simple that staff with little special training could employ it. The algorithm became the basis of the CAS Chemical Registry System (CAS Registry).

In late 1964 an experimental Chemical Registry System went into operation supporting the new publication Chemical-Biological Activities . By early 1965, the CAS Registry, no longer experimental, began to include all chemical substances indexed in Chemical Abstracts , with their structures and names recorded in computer-readable files. Every substance was given a permanent, unambiguous and unique identifying number, the CAS Registry Number.

To show the usefulness of the CAS Registry to researchers, think about a hypothetical new drug developed by a pharmaceutical company. This drug could have a systematic chemical name about 70 characters long, and be marketed under several different trade names. But it can be identified concisely by CAS Registry Number of up to 10 digits, such as 58-08-2 for caffeine. Today scientists and researchers around the world rely upon the CAS Registry Number as the globally accepted standard for defining and describing a chemical substance.

Though the system would go through several iterations over the years, it quickly became an integral part of CAS’s indexing procedures. More advanced versions were soon added which refined and improved nomenclature and the ability to recreate structure diagrams algorithmically. It took only ten years for the Registry to record three million unique structures. But the Registry's virtue is not limited to size or number; its success has eliminated the vagaries of chemical nomenclature since every unique substance gets a unique CAS Registry Number.

In the 1970s and 1980s the Chemical Abstracts Service adopted the tools of the new digital age—the computer, the internet, etc.—to assist CAS in fulfilling its core mission: Providing scientists with access to chemical literature and information. What changed were the methods of delivery (away from paper and traditional forms of publishing) and the speed with which CAS was able to deliver information to clients. In the past, chemists needing information might have to wait a day or several days for a librarian to find the requested references, which might not be entirely relevant. But in the digital age, scientists are only seconds from the information sought. Not only is information retrieval faster, but it can be done by the scientist himself.

CAS entered the electronic information age slowly. Before the 1980s online access to CAS databases went through commercial vendors. On November 1, 1980, CAS introduced CAS ONLINE ® , which provided access to about one-third of CAS's substance records. Gradually, other segments of the CAS Registry were added as search capacity increased. Although initially limited, CAS ONLINE ® permitted bench chemists and information experts to identify substances by specified molecular structures, something difficult, if not impossible, to do with printed materials. Although searching has been augmented over the years and the display of CAS Registry records has improved, the most remarkable advantage researchers derive from CAS ONLINE ® remains the ability to perform structure-based searching of the CAS database.

In 1983 CAS introduced CA File, which enabled subscribers to retrieve post-1967 bibliographic references. Other enhancement followed, but by the 1980s CAS began planning a new online network, one that grew out of an agreement between the American Chemical Society and the German scientific organization, FIZ Karlsruhe, to create an international network of databases to include areas beyond chemistry and chemical engineering. The result was STN SM International—the Scientific and Technical Information Network.

STN ® offered access to CAS files and Physics Briefs. Initially, the creation of STN ® provided European customers access to CAS files and search systems. Eventually, CAS databases would become available globally. As the CAS web site puts it: "STN ® is an online database service that provides global access to published research, journal literature, patents, structures, sequences, properties, and other data."

Dale Baker, who had ushered CAS into the digital age, retired in 1986 after serving as director for 28 years. Ronald Wigington, who had been director of research and development, succeeded Baker as director with no change in the emphasis on moving CAS toward the delivery of electronic information services. Wigington left in 1991 and was replaced a year later by Robert Massie.

Massie's first challenge was to insure CAS' financial well-being. At the same time, he wanted to guarantee CAS' leadership in providing scientific information. To further the latter, CAS moderated its price increases—to keep old and attract new customers—and strengthened product development. This meant even greater emphasis on electronic services in the 1990s as CAS embraced the Internet and World Wide Web as tools for distributing information. In 1995 CAS introduced CAplus SM , a database covering literature worldwide in chemistry, chemical engineering, biochemistry and related sciences since 1967.

A major launch in the 1990s was SciFinder ® . Much research went into the development of this forward-looking tool. Although the Internet was still in its infancy, CAS recognized the need for a new mode of data searching and retrieval. The rapid increase in personal computers meant that it would be possible to put chemists in direct connection with CAS databases. In 1991, CAS began to look into creating a desktop research tool, and the next year created a product development team. This group solicited views from CAS staff members and from customers. From users, the CAS researchers learned that scientists wanted more control over research and direct access to information. Moreover, the team understood that most scientists were not familiar with the language of information retrieval; accordingly, the search mechanisms had to be conversational and intuitive. In other words, users should not be asked to learn a command language, but rather they should be able to sit at their computer and use the system without training.

After extensive testing of prototypes by pharmaceutical and chemical companies, SciFinder ® was launched in 1995. From the beginning it allowed for simple interaction with the search system. The complex algorithms and other tools that buttress the CAS Registry and other CAS files remain in the background. In 1997 SciFinder ® Scholar TM appeared as a version of SciFinder ® for chemistry students and faculty.

CAS quickly adapted to the online environment as it became popular in the closing years of the 20th century. Web-based initiatives undertaken by CAS included creation in 1994 of its website, http://www.cas.org ; introduction of Chemical Patents Plus in 1996, which covers U.S. patents since 1974; STN ® Easy, also in 1996, to make access to some STN ® databases even easier; ChemPort ® in 1997, a joint service with ACS Publications to provide links from the records in the searchable databases to full-text journals and patents on the Web; a whole host of new STN ® products, including STN ® Express™, STN ® AnaVist™, STN ® on the Web SM ; and many others.

By 2007, when CAS celebrated its 100th anniversary, its databases demonstrated the exponential growth in scientific publishing and research. Those databases contained more than 27 million records of journal and patent literature, more than 170 million citations and more than 30 million substance records in the CAS Registry. In the words of Robert Massie, "CAS celebrates one hundred years of service to world science as an integral part of the American Chemical Society. That is a century in pursuit of a single mission—to provide access to chemical and related information that speeds and enables scientific discovery to improve people's lives."

• Chemical Abstracts Service History (Chemical Abstracts Service/ACS)

Landmark Designation

The American Chemical Society designated the Chemical Abstracts Service a National Historic Chemical Landmark in a ceremony at CAS headquarters in Columbus, Ohio, on June 14, 2007. The text of the commemorative plaque reads:

Founded in 1907 with the first publication of Chemical Abstracts TM , CAS has provided generations of scientists with unparalleled access to the most comprehensive collection of chemical information. The CAS Chemical Registry SM , established in 1965, is the recognized global standard for chemical substance identification and the largest database of chemical substances in the world. CAS continues to pursue its mission to provide access to chemical and related information that speeds and enables scientific discovery to improve people's lives .

Also on June 14, 2007, the American Chemical Society presented a plaque to The Ohio State University for its support of CAS, which was located on the OSU campus for many years. The text of the plaque presented to OSU reads:

From 1909 to 1965, The Ohio State University provided the American Chemical Society a range of support services and facilities that allowed the nascent Chemical Abstracts TM publication to grow into the world's most important resource for chemistry-related research. CAS moved to its own campus in 1965, adjacent to The Ohio State University, and cherishes the memory of that half century of generous and farsighted support.

Acknowledgments

Adapted for the internet from “Chemical Abstracts Service (CAS),” produced by the National Historic Chemical Landmarks program of the American Chemical Society in 2007.

American Chemical Society National Historic Chemical Landmarks. Chemical Abstracts Service (CAS). http://www.acs.org/content/acs/en/education/whatischemistry/landmarks/cas.html (accessed Month Day, Year).

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What is the CAS Registry Number? Why do I need it?

Chemical Abstracts Service (CAS) has a  registry system  for all completely identified chemical compounds or substances. There are over 144 million chemical substances & sequences currently registered and 12,000 new substances are added every day!! Each individual chemical substance is assigned a CAS Registry Number which may be thought of as that substance's "Social Security number."  (For more information, see  What does a CAS Registry Number look like? )

The rules of chemical nomenclature frequently change and each chemical substance is liable to have several names: i.e. trade or brand name(s); generic or common name(s); trivial or semisystematic name(s); and systematic or IUPAC name(s). For example, Tylenol is a brand name for acetaminophen which is itself a trivial name. The systematic name for this analgesic compound is Acetamide, N-(4-hydroxyphenyl)-. Another systematic name for this same compound is 4'-Hydroxyacetanilide. There is just one  CAS registry number which is  103-90-2 . Even if other names are created for this compound, the registry number will remain unchanged. There is no structural significance to the registry number - it is simply an identifier.

The most efficient and complete way to search for chemical substances in the  Chemical Abstracts Online  database is to use the CAS registry number(s).   A registry number may be searched as if it were a word, i.e.,  s 103-90-2  will search for information on Tylenol.  See  Using Native Commands to Search Chemical Abstracts Online  for more information on searching techniques.

CAS registry numbers are found in several print and electronic sources. These sources should be consulted before you develop your search strategy for  Chemical Abstracts Online . It is a good idea to verify registry numbers found in sources not published by CAS. This is because the registry number could represent some other form of the compound (e.g., stereoisomer, salt, or an incompletely defined form) than the one you want. To verify the registry number, select the Registry File by typing   file reg   into the search box in  Chemical Abstracts Online .  Enter  s ###-##-#  into the search box (###-##-# is the registry number - fill in the digits for the compound of interest). Check the record retrieved and make certain it is the desired substance before you use it in searching  Chemical Abstracts Online .

If the substance retrieved is not the one you want or you cannot find the CAS registry number in any of the sources listed below, you may then search the Registry File by substance name or molecular formula. A structure search may be attempted if all else fails but this type of search is expensive and can be complicated.

General sources containing CAS Registry Numbers

• Chemical Abstracts Index Guide . Columbus, OH: Chemical Abstracts Service, 1967-96 (ref QD 1 A51) There is an  Index Guide  for each collective 5-year period of  Chemical Abstracts . The  Index Guide  is published every 18 months and cumulated at the end of each collective period.  This is the "authority" list for both the print and online versions of  Chemical Abstracts .
• CRC Handbook of Chemistry and Physics . Cleveland, OH: CRC Press, published annually (ref QD 65 H3) *Older editions are in circulating collection (QD 65 H3).
• Gardner, William,  Gardner's Chemical Synonyms and Trade Names , 11th ed. Brookfield, VT: Gower, 1999 (ref TP 9 G286 1999)
• Hawley, Gessner Goodrich, et al,  Hawley's Condensed Chemical Dictionary , 16h ed. Hoboken, New Jersey: John Wiley & Sons, Incorporated,  2016
• Howard, Philip H. & Neal, Michael,  Dictionary of Chemical Names and Synonyms , Boca Raton, FL: Lewis Publishers, 1992 (ref TP 9 H65 1992)
• Kirk-Othmer Encyclopedia of Chemical Technology , 5th ed. NY: Wiley, 2004-2007, 26 volumes plus supplements.
• Buyer's Guide for Chemicals A directory of suppliers of chemicals and chemical products. More than 295,000 products are searchable by product name. (http://www.buyersguidechem.de)
• ChemExper Chemical Directory You may search this database of "chemicals available in the world" by registry number, molecular formula or by chemical name or synonyms in different languages. (http://www.chemexper.com/)
• ChemSpider Claims to be the "the richest single source of structure-based chemistry information" covering over 25 million compounds from almost 400 sources. You may search by systematic name, synonym, trade name, CAS registry number, etc. and find a wealth of information, including the CAS registry number. (http://www.chemspider.com)
• NIST Chemistry WebBook A gateway to the data collections of the National Institute of Standards and Technology (NIST), you can search for data on specific compounds by name, chemical formula, CAS registry number, molecular weight, or selected ion energetics and spectral properties. (http://webbook.nist.gov/)
• WIKIPEDIA (http://wikipedia.org) - "The Free Encyclopedia" has articles on chemical compounds written by and for chemists. Articles usually include CAS registry number and structural diagrams as well as alternate names, identifiers and properties with links to other sources of information.

Chemical catalogs containing CAS Registry Numbers

• Aldrich Chemical Company,  Aldrich Chemistry : Handbook of Fine Chemicals , Milwaukee, WI: Sigma-Aldrich (ref TP 202 A38)
• Sigma Chemical Company,  Biochemicals, Reagents & Kits for Life Science Research , St. Louis, MO: Sigma Chemical Co. (ref TP 202 S54)
• Fisher Scientific You may search the Fisher Scientific chemical catalogs by chemical name, molecular formula, catalog number, or key word. Choose "Advanced Search" to get all of the search options. Contains over 2,400 chemicals and material safety data sheets (MSDS's). (https://www.fishersci.com)
• Spectrum Chemicals & Laboratory Products You may search Spectrum Chemicals by chemical name, keyword, CAS registry number, FEMA number, color index number, and molecular formula. (http://www.spectrumchemical.com/)
• WWW Chemicals Another searchable collection of chemical catalogs which may be searched by chemical name, CAS registry number, field of expertise, molecular formula, etc. (http://www.chem.com/catalogs/)

Inorganic and Organic Compounds containing CAS Registry Numbers

INORGANIC COMPOUNDS

• Dictionary of Inorganic Compounds , 1st ed. NY: Chapman and Hall, 1992 (ref QD 148 D53 1992) 5-volume set and 1st-2nd annual supplements.

ORGANIC COMPOUNDS

• CRC Handbook of Data on Organic Compounds , 2nd ed. Boca Raton, FL: CRC Press, 1989 (ref QD 257.7 H36 1989) 10 volume set.
• Dictionary of Organic Compounds , 5th ed. NY: Chapman and Hall, 1982 (ref QD 246 D5 1982) 7 volume set and 1st-10th annual supplements (1982-1992).
• Handbook of Physical Properties of Organic Chemicals ,   Boca Raton, FL: CRC Press, 1997  (ref  QD 257.7 H374 1997

Drugs and Biologically Important Compunds containing CAS Registry Numbers

• Merck Index , Rahway, NJ: Merck & Co., published every 7-8 years  (ref RS 51 M4)  Library has latest three editions.
• PubChem A set of three databases: PubChem Compound, PubChem Substance, and PubChem Bioassay. PubChem provides information on the biological activities of small molecules. Depending on the source of the data, the results can include registry numbers but may not identify them as such.(http://pubchem.ncbi.nlm.nih.gov/).

Pesticides containing CAS Registry Numbers

• Briggs, Shirley A.  Basic Guide to Pesticides: their characteristics and hazards,  Washington, DC: Hemisphere, 1992 (ref SB 951 B75 1992)
• Crop Protection Handbook , Willoughby, OH: Meister PubCo, published annually. HSU Library has 2005 edition. (ref S 633 A5)
• Montgomery, John H.  Agrochemicals Desk Reference , 2nd edition.  Boca Raton, FL: CRC Press, 1997 (ref TD 196 A34 M66 1997)
• Worthing, Charles R.  The Pesticide Manual , 9th ed. Surrey, UK: British Crop Protection Council, 1991 (ref SB 951 P434 1991)
• EXTOXNET (Extension Toxicology Network) - A cooperative effort of UC Davis, Oregon State University, Michigan State University, Cornell University, and the University of Idaho - contains over 130 Pesticide Information Profiles on specific pesticides. (http://ace.orst.edu/info/extoxnet/ghindex.html)
• National Pesticide Information Center (NPIC) NPIC's mission is "to serve as a source of factual, unbiased information on pesticide chemistry, toxicology, and environmental fate." In addition to other information, NPIC has "active ingredient" fact sheets. (http://npic.orst.edu)

Toxic or Hazardous Substances containing CAS Registry Numbers

• Beim, Howard J.   Rapid Guide to Hazardous Air Pollutants .  NY: Van Nostrand Reinhold, 1998 (ref TD 883.1 B37 1998)
• Book of Lists for Regulated Hazardous Substances , 10th ed. Rockville, MD: The Institutes, 2001 (ref TD 1032 B66 2001)
• Bretherick, L.,  Bretherick's Handbook of Reactive Chemical Hazards , 6th ed. Oxford ; Boston : Butterworth-Heinemann, 1999 (ref T 55.3 H3 B73 1999)
• Keith, Lawrence H. & Walker, Mary M.,  Handbook of Air Toxics: sampling, analysis, and properties . Boca Raton, FL: Lewis Publishers, 1995 (ref TD 890 K4 1995)
• Lewis, Richard J., Sr.,  Hazardous Chemicals Desk Reference,  5th ed. NY: Wiley, 2002  (ref T 55.3 H3 L49 2002)
• Lewis, Richard J., Sr., & Sax, N. Irving,  Sax's Dangerous Properties of Industrial Materials , 10th ed. NY: Wiley, 2000 (ref T55.3 H3 L494 2000) 3-volume set
• Mackay, Donald, et al,  Illustrated Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals . Boca Raton, FL: Lewis Publishers, 1992-1997 (ref TD 196 O73 M32 1992) 5-volume set
• Montgomery, John H. & Welkom, Linda M.,  Groundwater Chemicals Desk Reference , 3rd ed. Chelsea, MI: Lewis Publishers, 2000 (ref TD 426 M66 2000)
• National Institute for Occupational Safety and Health,  NIOSH Pocket Guide to Chemical Hazards . Cincinnati, OH: NIOSH, 1997 (Docs HE 20.7108:C42/997)
• Pohanish, Richard P.,  Wiley Guide to Chemical Incompatibilities , 2nd ed. Hoboken NJ: J. Wiley, 2003  (ref T 55.3 H3 P647 2003)
• Pohanish, Richard P.,  Rapid Guide to Hazardous Chemicals in the Environment . NY: Van Nostrand Reinhold, 1997  (ref RA 1226 P64 1997)
• Pohanish, Richard P.,   Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens , 4th ed. Park Ridge, NJ: Noyes Publications, 2002 (ref RA 1215 .S58 2002) 2-volume set
• Proctor, Nick H.,  Proctor and Hughes' Chemical Hazards of the Workplace , 4th ed., NY: Van Nostrand Reinhold, 1996 (ref RA 1229 P76 1996)
• Sheftel, Victor O.,  Handbook of Toxic Properties of Monomers and Additives . Boca Raton, FL: Lewis Publishers, 1995  (ref RA 1242 P66 S54 1995)
• Shepard, Thomas H.,  Catalog of Teratogenic Agents , 11th ed. Baltimore, MD: Johns Hopkins University Press, 2004 (ref QM 691 S53 2004)
• Sittig, Marshall,  World-Wide Limits for Toxic and Hazardous Chemicals in Air, Water and Soil . Park Ridge, NJ: Noyes Publications, 1994 (ref RA 1229.5 S58 1994)
• Consumer Products Information Database Enter Products, Manufacturers, Chemicals, Product Categories and Product Types
• Material Safety Data Sheets A collection of sites where you can get MSDS's. Most of these sites are searchable by chemical name, manufacturer name, and/or CAS registry number.

Content Attribution

Some of the content of this page was created in another format by Sharon Chadwick, HSU Librarian, retired 06/2013. 

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Welcome to the Chemical Ingredient Application

Search for Chemical Ingredient by Partial Name, Chemical Code or CAS Number

Back to Databases

This query yields a list of chemical ingredient names that meets the criteria you specify below. Matches are returned with the chemical name and a highlighted chemical code, which links to a screen report with the option of current registration information from the Product/Label Database.

For best results, see detailed INSTRUCTIONS .

Search by chemical name or code

Enter 1) a full or partial chemical name, synonym, or trade name, or 2) a DPR chemical code. Chemical name or code should be less than 50 characters.

Search by CAS number

CAS number is a numeric designation given to a specific chemical compound by the Chemical Abstract Service. Enter a full or partial CAS number, with or without the dashes. CAS number should be less than 50 characters.

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How CAS Numbers Are Assigned to Chemicals

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Every chemical is assigned a CAS Number. Have you ever wondered what a CAS Number is and how they are assigned? Check out this very simple explanation that will give you everything you need to know about what a CAS Number is, plus how CAS Numbers are assigned.

The Chemical Abstract Service or CAS

The Chemical Abstract Service is a division of the American Chemical Society, and it maintains a database of chemical compounds and sequences. The CAS database currently contains over 55 million different organic and inorganic chemical compounds. Each CAS entry is identified by their CAS Registry Number, or CAS Number for short.

CAS Numbers

CAS Numbers are up to 10 digits long using the format xxxxxxx-yy-z. They are assigned to a compound as the CAS registers a new compound . The number has no significance to the chemistry, structure, or chemical nature of the molecule.

The CAS Number of a compound is a useful way to identify a chemical over its name. For example, the compound CAS 64-17-5 refers to ethanol. Ethanol is also known as ethyl alcohol, ethyl hydrate, absolute alcohol, grain alcohol or hydroxyethane. The CAS Number is the same for all these names.

The CAS Number can also be used to distinguish between stereoisomers of a compound. Glucose is a ​sugar molecule that has two forms: D-glucose and L-glucose. D-glucose is also called dextrose and has CAS Number 50-99-7. L-glucose is the mirror image of D-glucose and has a CAS Number of 921-60-8.

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Search Chemicals

Mychemicals, about cameo chemicals.

CAMEO Chemicals is a database of hazardous chemical datasheets that emergency responders and planners can use to get response recommendations and predict hazards—such as explosions or toxic fumes.

This tool is part of the CAMEO® software suite and you may want to review the terms and conditions for using CAMEO Chemicals.

Key Program Features

• Search by name, CAS (Chemical Abstracts Service) number, or UN/NA (United Nations/North American) number to find chemicals of interest in the extensive database of thousands of hazardous substances.
• Review chemical datasheets for physical properties, health hazards, information about air and water hazards, recommendations for firefighting, first aid, and spill response, and regulatory information.
• Get information from additional sources using the U.S. Coast Guard CHRIS (Chemical Hazards Response Information System) manual, the NIOSH (National Institute for Occupational Safety and Health) Pocket Guide, and International Chemical Safety Cards links on many chemical datasheets.
• Access UN/NA datasheets for response information from the Emergency Response Guidebook (ERG) and shipping information from the Hazardous Materials Table. ERG Response Guide PDFs are available in English, Spanish, and French.
• Predict potential hazards that could arise if chemicals were to mix.

Multiple Formats

Tip: If you're using the online formats, you can switch between the website and the mobile website using the links at the bottom of the webpage—and CAMEO Chemicals will maintain your session data. For example, you could use the mobile site to build a MyChemicals collection, and then click on the Full Site link to generate and print the report.

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How to Access the TSCA Inventory

The non-confidential portion of EPA’s Toxic Substances Control Act Chemical Substance Inventory (TSCA Inventory) is updated approximately every six months. It can be searched in multiple ways. This page provides ways to download the non-confidential Inventory and offers help in using these downloaded files. The May 2024 update is available below. The Inventory contains 86,770 chemicals, of which 42,377 are active.

On this page:

Download the non-confidential TSCA Inventory

• Learn how the data is formatted to help you search

Meaning of EPA regulatory flags

Alternate ways to access the non-confidential tsca inventory.

EPA provides a Microsoft Access version and a generic comma-delimited "CSV" text version of the non-confidential TSCA Inventory for users to download. If you don't have Microsoft Access, use the CSV file. Both files are compressed ".zip" files. The .zip files contain the actual data files. See generic information about zip files . ​

MS Access Non-CBI TSCA Inventory (zip) (Last created: 05/2024)

CSV Non-CBI TSCA Inventory (zip) (Last created: 05/2024)

The Microsoft Access file contains two tables:

• Contains non-confidential chemical substance listings on the TSCA Inventory, as identified by Chemical Abstract Service (CAS) Registry Number and Chemical Abstracts (CA) Index Name.
• Contains non-confidential data for the confidential chemical substance listings, as identified by EPA accession number and generic chemical name.

The Comma Separated Value (CSV) text version contains two *.CSV tables:

• Contains non-confidential chemical substance listings on the TSCA Inventory, as identified by CAS Registry Number and CA Index Name.

For all files: users may need to adjust formatting, including column widths.

Learn how the data is formatted to help you search 

You can perform basic searches or sort the information in different ways.

• Use a basic "find" search function and type in a part of a chemical name or CAS Registry Number.
• You may be able to do different or more complex searches or sorts -- see your own software help system or your local computer support personnel for additional instructions.

The following data fields are provided for each non-confidential chemical substance:

The following non-confidential data fields are provided for each confidential chemical substance:

NOTE: A "Chemical Substance Definition" in the DF field provides important identification information for certain Class 2 substances having "Preferred CA Index Names" that are not specific or complete enough to permit unambiguous identification of the substance or the category to which it belongs.

The presence of "UVCB" in the UV field indicates the substance is a Class 2 substance within the UVCB group, i.e., those with “unknown” or “variable composition,” “complex reaction products” and “biological materials.” These substances have no definite molecular formula representation and either partial or no structural diagrams.

Read our policy and guidance documents about Class 2 substances on the Inventory.

The ASCII character set is used, with Field IDs in upper case and the data themselves in upper and lower case. Special characters are handled using the following conventions:

• Greek letters - name of letter within periods, e.g., the alpha is represented as ".alpha."
• The degree sign in temperatures is represented as ".degree."

All fields pertaining to a particular chemical substance are grouped together into a single substance record. For ease of use with data management software, records are separated from each other by a carriage return and a newline. The last (eighth) field ends with a carriage return and a newline instead of a tab.

All field identifiers are present in a record even if some fields have no data. If there are no data, the field ID (with colon) is immediately followed by a tab unless it is the last field of the record, in which case the field ID (with colon) is immediately followed by a carriage return and newline. As indicated above, the SN and FL fields can have multiple values of data. In such cases, each value is separated from the one following by a semicolon followed by a space.

Special flags are used throughout the TSCA Inventory to identify those substances on the Inventory that are the subject of an EPA rule or order promulgated under TSCA, as well as to indicate types of full or partial exemptions from TSCA reporting requirements.

The following flags are used:

• 5E - indicates a substance that is the subject of a TSCA section 5(e) order.
• 5F - indicates a substance that is the subject of a TSCA section 5(f) rule.
• 12C - indicates a substance that is prohibited to be exported from the Unites States under TSCA section 12(c). 
• FRI - indicates a polymeric substance containing no free-radical initiator in its Inventory name but is considered to cover the designated polymer made with any free-radical initiator regardless of the amount used.
• PE1 - indicates a polymer that has a number-average molecular weight of greater than or equal to 1,000 daltons and less than 10,000 daltons and that is exempt under the 1995 polymer exemption rule. The polymer's oligomer content must be less than 10 percent by weight below 500 daltons and less than 25 percent by weight below 1,000 daltons.
• PE2 - indicates a polymer that has a number-average molecular weight of greater than or equal to 10,000 daltons and that is exempt under the 1995 polymer exemption rule. The polymer's oligomer content must be less than 2 percent by weight below 500 daltons and less than 5 percent by weight below 1,000 daltons.
• PE3 - indicates a polymer that is a polyester and that is exempt under the 1995 polymer exemption rule. The polyester is made only from monomers and reactants included in a specified list that comprises one of the eligibility criteria for the 1995 polymer exemption rule.
• PMN - indicates a commenced PMN substance.
• R - indicates a substance that is the subject of a proposed or final TSCA section 6 risk management rule.
• S - indicates a substance that is identified in a final Significant New Use Rule.
• SP - indicates a substance that is identified in a proposed Significant New Use Rule.
• T - indicates a substance that is the subject of a final TSCA section 4 test rule or order.
• TP - indicates a substance that is the subject of a proposed TSCA section 4 test rule or order.
• XU - indicates a substance exempt from reporting under the Chemical Data Reporting Rule, (40 CFR 711).
• Y1 - indicates a polymer that has a number-average molecular weight greater than 1,000 and that was exempt under the 1984 polymer exemption rule.
• Y2 - indicates a polymer that is a polyester and that was exempt under the 1984 polymer exemption rule. The polyester is made only from reactants included in a specified list of low-concern reactants that comprises one of the eligibility criteria for the 1984 polymer exemption rule.

In addition to downloading a Microsoft Access version and a generic comma-delimited "CSV" text version, the non-confidential TSCA Inventory can be searched in multiple ways:

Use EPA's Substance Registry Services (SRS) to search the non-confidential TSCA Inventory

• Go to Substance Registry Services  (link opens in a new tab)
• Select the “search by list" option
• Type "TSCA Inventory" in the List Name field
• Click the "filter" button and select " TSCA Inventory – TSCA Inv " from the drop-down list

Look at other sources of EPA’s non-confidential TSCA Inventory data such as:

• Government Printing Office (GPO) website  no longer provides paper copies of the original 1985 TSCA Inventory publication or the 1990 Supplement; however, it can provide expert assistance in finding and using related U.S. government information.
• Several commercial services provide searches for the non-confidential TSCA Inventory for a fee. None of these is connected to or has a specific endorsement from EPA.
• TSCA Inventory Home
• About the Inventory
• Access the Inventory
• Policy and Guidance