Most Frequently Asked Questions about Toxicology

Toxicology is the study of the adverse effects of substances on living things. From a brief summary of the toxicity of a given substance, to comprehensive literature search in support of a regulatory submission, the Dialog^® service can provide your answers.

Where do I start?

A. Start with the name of the toxic substance. This may include trade names, synonyms, and a Chemical Abstracts Service (CAS^®) Registry Number, unique to that substance.

• If you have a list of substances, divide them into "rare" and "common or highly toxic." This will determine your search path as much as any other factor. A good test is to SELECT the name of the substance in ToxFile^® (File 156), and look at the number of records. You may get only a few because the substance is rare or because it is generally non-toxic or because the name you are using is not the commonest name for the substance.
• If you need to search for synonyms for your compound, start in Chapman and Hall Chemical Database (File 303), The Merck Index Online^SM (File 304) and Registry of Toxic Effects of Chemical Substances (RTECS^®) (File 336). S NA=benzene and then type out in format 8,sy to view the synonyms, or you may want to TYPE out the full records in Format 9, for comprehensive details.
• Cengage/Gale Health & Wellness Database^SM (File 149) is another good place to look for overview articles, and many of them are fulltext in this file (SELECT S1/FULLTEXT). File 149 is especially good for adverse effects of vitamins, minerals, herbal remedies, medications, folk medicines, and poisonous plants.
• The Registry of Toxic Effects of Chemical Substances (RTECS^®) (File 336) is a basic toxicology reference file file containing toxicity information on over 150,000 chemical substances including pesticides, prescription and non-prescription drugs.

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How do I perform a very comprehensive search? Or, I only got a few records; how do I expand my search?

A. Start in Embase^® (File 73). EXPAND your substance, in parentheses, e.g., EXPAND (BENZENE), to get into the thesaurus. Capture the display of names and numbers associated with your substance.

• Then BEGIN the three chemical files mentioned above (Files 303, 304, 336), and EXPAND NA=<substance name>. SELECT an entry, usually E3, from the EXPAND screen and TYPE out the resulting set to see the CAS Registry Numbers and synonyms for the substance. (See the Bluesheets for details on predefined format options.) Then enter MAP SYRN TEMP. This will form a TEMPorarily SAVEd search to EXECUTE in the literature files. If you plan to LOGOFF here, write down the SAVEd search serial number, e.g., TA001, for use later.
• Now BEGIN the literature files that relate to your search. For example, you might choose MEDLINE^® (File 155) for mutagens. Enter EXECUTE STEPS TA001 (or EXS TA001) in the files to form a set. S S1 and MUTAGENS/DE
• Compare the names for the substance which you got from EMBASE, and SELECT any that are not in the MAP from the chemical files, using the OR operator to form a final set containing all the substance names.
• Be sure to include ToxFile (File 156), but only File 156 assumes the toxicology concept in the whole file. Enter SELECT S1 FROM 156 to form your third set, assuming you didn't need to add a set of synonyms from Embase. SELECT S2 AND (TOXIC? OR TOXIN? OR POISON? OR HAZARD? OR ADVERSE OR SAFETY OR SAFE) as your fourth set, and SELECT S3 OR S4. Note: these set numbers may be higher if your EXS formed more than one set or if you added a set with additional synonyms.
• Then REMOVE DUPLICATES (RD). Be sure to get the record count down to a reasonable amount of records before entering the RD command. You can LIMIT to a publication year range, or English language, or to certain keywords or descriptors. There are many duplicates within ToxFile itself, as a result of the many subfiles from which it is constructed. The RD algorithm will keep the record with the highest accession number, not necessarily the one with a long abstract, so that is one last place to look if you have not yet found a readable summary of the toxicity of your substance.
• The TOXICOL, SAFETY, ENVIRON, and POLLUT categories are also available, for searching in both DIALINDEX^® (File 411) and as OneSearch^® categories. You may find more articles on a rare substance by searching these groups of files. Apply the "toxic" synonyms after you actually BEGIN the files, to save time in DIALINDEX.

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Are all the toxicology files literature files?

A. No, several are online "handbooks" or lists, with one substance per record. Registry of Toxic Effects of Chemical Substances (RTECS^®) (File 336) as well as Material Safety Data Sheets – OHS™ (File 332) are files of this type.

• EXPAND NA= (for Name in File 336) and the common name of your substance, and SELECT the basic record.
• There is a Reference Guide to RTECS, and even if you are a toxicologist, you may need the Guide to interpret the records. To see the abbreviations in the data fields spelled out, use Format 9. Do not be surprised to see studies from older decades cited as proof of toxicity, teratogenicity, etc. Many of them are difficult to retrieve for the reason that they are older or non-English articles, but if a substance has been known as a toxin for many years, the original study is still cited.

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How do I know if this substance is safe to eat?

A. The Food & Drug Administration (FDA) does declare some substances as being "generally regarded as safe." They announce these rulings in the Federal Register (File 180), but there is no reliable terminology to select only those records, and no list online. Contact the FDA at 1-888-723-3366 or email industry@fda.gov or consumer@fda.gov.

REVISED OCTOBER 2012

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